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Sample records for vibrational mode optical

  1. Optically active vibrational modes of PPV derivatives on textile substrate

    International Nuclear Information System (INIS)

    Silva, M.A.T. da; Dias, I.F.L.; Santos, E.P. dos; Martins, A.A.; Duarte, J.L.; Laureto, E.; Reis, G.A. dos; Guimarães, P.S.S.; Cury, L.A.

    2013-01-01

    In this work, MEH-PPV and BDMO-PPV films were deposited by spin-coating on “dirty” textile substrates of canvas, nylon, canvas with resin, jeans and on glass and the temperature dependence of the optical properties of them was studied by photoluminescence and Raman (300 K) techniques. The temperature dependence of the energy, of the half line width at half height of the purely electronic peak, of the integrated PL intensity and of the Huang-Rhys factor, S=I (01) /I (00) , were obtained directly from the PL spectrum. For an analysis of the vibrational modes involved, Raman measurements were performed on substrates with and without polymers deposited and the results compared with those found in the literature. The films of MEH-PPV and BDMO-PPV showed optical properties similar to those films deposited on other substrates such as glass, metals, etc. It was observed an inversion of the first vibrational band in relation to the purely electronic peak with increasing temperature in the films deposited on nylon and canvas. The vibrational modes obtained by Raman were used to compose the simulation of the PL line shape of BDMO-PPV films on canvas and nylon, using a model proposed by Lin [29]. - Highlights: ► MEH-PPV and BDMO-PPV films were deposited by spin-coating on dirty textile. ► Their properties were studied by photoluminescence and Raman techniques. ► We observed inversion of first vibrational band in relation to purely electronic peak. ► Optically active vibrational modes of PPV derivatives were studied.

  2. Fiber-Optic Vibration Sensor Based on Multimode Fiber

    Directory of Open Access Journals (Sweden)

    I. Lujo

    2008-06-01

    Full Text Available The purpose of this paper is to present a fiberoptic vibration sensor based on the monitoring of the mode distribution in a multimode optical fiber. Detection of vibrations and their parameters is possible through observation of the output speckle pattern from the multimode optical fiber. A working experimental model has been built in which all used components are widely available and cheap: a CCD camera (a simple web-cam, a multimode laser in visible range as a light source, a length of multimode optical fiber, and a computer for signal processing. Measurements have shown good agreement with the actual frequency of vibrations, and promising results were achieved with the amplitude measurements although they require some adaptation of the experimental model. Proposed sensor is cheap and lightweight and therefore presents an interesting alternative for monitoring large smart structures.

  3. Optical phonon modes of wurtzite InP

    Science.gov (United States)

    Gadret, E. G.; de Lima, M. M.; Madureira, J. R.; Chiaramonte, T.; Cotta, M. A.; Iikawa, F.; Cantarero, A.

    2013-03-01

    Optical vibration modes of InP nanowires in the wurtzite phase were investigated by Raman scattering spectroscopy. The wires were grown along the [0001] axis by the vapor-liquid-solid method. The A1(TO), E2h, and E1(TO) phonon modes of the wurtzite symmetry were identified by using light linearly polarized along different directions in backscattering configuration. Additionally, forbidden longitudinal optical modes have also been observed. Furthermore, by applying an extended 11-parameter rigid-ion model, the complete dispersion relations of InP in the wurtzite phase have been calculated, showing a good agreement with the Raman experimental data.

  4. Vibrational lifetimes of protein amide modes

    International Nuclear Information System (INIS)

    Peterson, K.A.; Rella, C.A.

    1995-01-01

    Measurement of the lifetimes of vibrational modes in proteins has been achieved with a single frequency infrared pump-probe technique using the Stanford Picosecond Free-electron Laser, These are the first direct measurements of vibrational dynamics in the polyamide structure of proteins. In this study, modes associated with the protein backbone are investigated. Results for the amide I band, which consists mainly of the stretching motion of the carbonyl unit of the amide linkage, show that relaxation from the first vibrational excited level (v=1) to the vibrational ground state (v=0) occurs within 1.5 picoseconds with apparent first order kinetics. Comparison of lifetimes for myoglobin and azurin, which have differing secondary structures, show a small but significant difference. The lifetime for the amide I band of myoglobin is 300 femtoseconds shorter than for azurin. Further measurements are in progress on other backbone vibrational modes and on the temperature dependence of the lifetimes. Comparison of vibrational dynamics for proteins with differing secondary structure and for different vibrational modes within a protein will lead to a greater understanding of energy transfer and dissipation in biological systems. In addition, these results have relevance to tissue ablation studies which have been conducted with pulsed infrared lasers. Vibrational lifetimes are necessary for calculating the rate at which the energy from absorbed infrared photons is converted to equilibrium thermal energy within the irradiated volume. The very fast vibrational lifetimes measured here indicate that mechanisms which involve direct vibrational up-pumping of the amide modes with consecutive laser pulses, leading to bond breakage or weakening, are not valid

  5. Local-mode vibrations of water

    International Nuclear Information System (INIS)

    Lawton, R.T.; Child, M.S.

    1981-01-01

    Quantum-mechanical eigenvalues for the stretching vibrations of H 2 O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm - 1 at v=1 to 0.001 cm - 1 at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode. (author)

  6. Resolving fine spectral features in lattice vibrational modes using femtosecond coherent spectroscopy

    Directory of Open Access Journals (Sweden)

    A. Card

    2016-02-01

    Full Text Available We show resolution of fine spectral features within several Raman active vibrational modes in potassium titanyl phosphate (KTP crystal. Measurements are performed using a femtosecond time-domain coherent anti-Stokes Raman scattering spectroscopy technique that is capable of delivering equivalent spectral resolution of 0.1 cm−1. The Raman spectra retrieved from our measurements show several spectral components corresponding to vibrations of different symmetry with distinctly different damping rates. In particular, linewidths for unassigned optical phonon mode triplet centered at around 820 cm−1 are found to be 7.5 ± 0.2 cm−1, 9.1 ± 0.3 cm−1, and 11.2 ± 0.3 cm−1. Results of our experiments will ultimately help to design an all-solid-state source for sub-optical-wavelength waveform generation that is based on stimulated Raman scattering.

  7. Local-mode vibrations of water

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

    1981-05-11

    Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at v=1 to 0.001 cm/sup -1/ at v=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

  8. Local-mode vibrations of water

    Energy Technology Data Exchange (ETDEWEB)

    Lawton, R.T.; Child, M.S. (Oxford Univ. (UK). Dept. of Theoretical Chemistry)

    1981-05-11

    Quantum-mechanical eigenvalues for the stretching vibrations of H/sub 2/O on the Sorbie-Murrell potential surface are shown to contain a series of local-mode doublets, with splittings which vary as the energy increases from 100 cm/sup -1/ at theta=1 to 0.001 cm/sup -1/ at theta=8. Preliminary calculations indicate that this pattern is largely unaffected by inclusion of the bending vibrational mode.

  9. Multi-mode vibration control of piping system

    International Nuclear Information System (INIS)

    Minowa, Takeshi; Seto, Kazuto; Iiyama, Fumiya; Sodeyama, Hiroshi

    1999-01-01

    In this paper, dual dynamic absorbers are applied to the piping system in order to control the multiple vibration modes. ANSYS, which is one of the software based on FEM(finite element method), is used for the design of dual dynamic absorbers as well as for the determination of their optimum installing positions. The dual dynamic absorbers designed optimally for controlling the first three vibration modes perform just like a houde damper in higher frequency and have an effect on controlling higher modes. To use this advantage, three dual dynamic absorbers are installed in positions where they influence higher modes, and not only the first three modes of the piping system but also the extensive modes are controlled. Practical experimental study has also been carried out and it is shown that a dual dynamic absorber is suitable for controlling the vibration of the piping system. (author)

  10. Laterally vibrating resonator based elasto-optic modulation in aluminum nitride

    Directory of Open Access Journals (Sweden)

    Siddhartha Ghosh

    2016-06-01

    Full Text Available An integrated strain-based optical modulator driven by a piezoelectric laterally vibrating resonator is demonstrated. The composite structure consists of an acoustic Lamb wave resonator, in which a photonic racetrack resonator is internally embedded to enable overlap of the guided optical mode with the induced strain field. Both types of resonators are defined in an aluminum nitride (AlN thin film, which rests upon a layer of silicon dioxide in order to simultaneously define optical waveguides, and the structure is released from a silicon substrate. Lateral vibrations produced by the acoustic resonator are transferred through a partially etched layer of AlN, producing a change in the effective index of the guided wave through the interaction of the strain components with the AlN elasto-optic (p coefficients. Optical modulation through the elasto-optic effect is demonstrated at electromechanically actuated frequencies of 173 MHz and 843 MHz. This device geometry further enables the development of MEMS-based optical modulators in addition to studying elasto-optic interactions in suspended piezoelectric thin films.

  11. Surface vibrational modes in disk-shaped resonators.

    Science.gov (United States)

    Dmitriev, A V; Gritsenko, D S; Mitrofanov, V P

    2014-03-01

    The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90 mm and thickness of 16 mm in the frequency range of 130-200 kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10(-5). The Q-factors of all modes measured in vacuum lie in the interval (2…3)×10(5). This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The use of an optical data acquisition system for bladed disk vibration analysis

    Science.gov (United States)

    Lawrence, C.; Meyn, E. H.

    1985-01-01

    A new concept in instrumentation was developed by engineers at NASA Lewis Research Center to collect vibration data from multi-bladed rotors. This new concept, known as the optical data acquisition system, uses optical transducers to measure bladed tip deflections by reflection of light beams off the tips of the blades as they pass in front of the optical transducer. By using an array of transducers around the perimeter of the rotor, detailed vibration signals can be obtained. In this study, resonant frequencies and mode shapes were determined for a 56 bladed rotor using the optical system. Frequency data from the optical system was also compared to data obtained from strain gauge measurements and finite element analysis and was found to be in good agreement.

  13. Distributed Fiber-Optic Sensors for Vibration Detection.

    Science.gov (United States)

    Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

    2016-07-26

    Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

  14. Vibration measurement on composite material with embedded optical fiber based on phase-OTDR

    Science.gov (United States)

    Franciscangelis, C.; Margulis, W.; Floridia, C.; Rosolem, J. B.; Salgado, F. C.; Nyman, T.; Petersson, M.; Hallander, P.; Hällstrom, S.; Söderquist, I.; Fruett, F.

    2017-04-01

    Distributed sensors based on phase-optical time-domain reflectometry (phase-OTDR) are suitable for aircraft health monitoring due to electromagnetic interference immunity, small dimensions, low weight and flexibility. These features allow the fiber embedment into aircraft structures in a nearly non-intrusive way to measure vibrations along its length. The capability of measuring vibrations on avionics structures is of interest for what concerns the study of material fatigue or the occurrence of undesirable phenomena like flutter. In this work, we employed the phase-OTDR technique to measure vibrations ranging from some dozens of Hz to kHz in two layers of composite material board with embedded polyimide coating 0.24 numerical aperture single-mode optical fiber.

  15. Quantum-Chemical Calculation and Visualization of the Vibrational Modes of Graphene in Different Points of the Brillouin Zone.

    Science.gov (United States)

    Lebedieva, Tetiana; Gubanov, Victor; Dovbeshko, Galyna; Pidhirnyi, Denys

    2015-12-01

    Different notations of graphene irreducible representations and optical modes could be found in the literature. The goals of this paper are to identify the correspondence between available notations, to calculate the optical modes of graphene in different points of the Brillouin zone, and to compare them with experimental data obtained by Raman and coherent anti-Stokes Raman scattering (CARS) spectroscopy. The mechanism of the resonance enhancement of vibration modes of the molecules adsorbed on graphene in CARS experiments is proposed. The possibility of appearance of the discrete breathing modes is discussed.

  16. Vibration mode and vibration shape under excitation of a three phase model transformer core

    Science.gov (United States)

    Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

    2018-04-01

    Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

  17. Zero-point vibrational effects on optical rotation

    DEFF Research Database (Denmark)

    Ruud, K.; Taylor, P.R.; Åstrand, P.-O.

    2001-01-01

    We investigate the effects of molecular vibrations on the optical rotation in two chiral molecules, methyloxirane and trans-2,3-dimethylthiirane. It is shown that the magnitude of zero-point vibrational corrections increases as the electronic contribution to the optical rotation increases....... Vibrational effects thus appear to be important for an overall estimate of the molecular optical rotation, amounting to about 20-30% of the electronic counterpart. We also investigate the special case of chirality introduced in a molecule through isotopic substitution. In this case, the zero-point vibrational...

  18. Vibrational Mode-Specific Autodetachment and Coupling of CH2CN-

    Science.gov (United States)

    Lyle, Justin; Mabbs, Richard

    2017-06-01

    The Cyanomethyl Anion, CH_{2}CN-, and neutral radical have been studied extensively, with several findings of autodetachment about the totally symmetric transition, as well as high resolution experiments revealing symmetrically forbidden and weak vibrational features. We report photoelectron spectra using the Velocity-Mapped Imaging Technique in 1-2 \\wn increments over a range of 13460 to 15384 \\wn that has not been previously examined. These spectra include excitation of the ground state cyanomethyl anion into the direct detachment thresholds of previously reported vibrational modes for the neutral radical. Significant variations from Franck-Condon behavior were observed in the branching ratios for resolved vibrational features for excitation in the vicinity of the thresholds involving the νb{3} and νb{5} modes. These are consistent with autodetachment from rovibrational levels of a dipole bound state acting as a resonance in the detachment continuum. The autodetachment channels involve single changes in vibrational quantum number, consistent with the vibrational propensity rule but in some cases reveal relaxation to a different vibrational mode indicating coupling between the modes and/or a breakdown of the normal mode approximation.

  19. Sensibility to Changes of Vibrational Modes of Excited Electron: Sum Frequency Signals Versus Difference Frequency Signals

    International Nuclear Information System (INIS)

    Gu Anna; Liang Xianting

    2011-01-01

    In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the vibrational modes of the electronic two-level system. Because the SFG conversion efficiency can be improved by using the time-delay method, the findings in this paper predict that the SFG spectrum may probe the changes of the microstructure more effectively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  20. Self-excited multi-scale skin vibrations probed by optical tracking micro-motions of tracers on arms

    Science.gov (United States)

    Chen, Wei-Chia; Chen, Hsiang-Ying; Chen, Yu-Sheng; Tian, Yong; I, Lin

    2017-07-01

    The self-excited multi-scale mechanical vibrations, their sources and their mutual coupling of different regions on the forearms of supine subjects, are experimentally investigated, using a simple noncontact method, optical video microscopy, which provides 1 μm and 25 ms spatiotemporal resolutions. It is found that, in proximal regions far from the radial artery, the vibrations are the global vibrations of the entire forearm excited by remote sources, propagating through the trunk and the limb. The spectrum is mainly composed of peaks of very low frequency motion (down to 0.05 Hz), low frequency respiration modes, and heartbeat induced modes (about 1 Hz and its harmonics), standing out of the spectrum floor exhibiting power law decay. The nonlinear mode-mode coupling leads to the cascaded modulations of higher frequency modes by lower frequency modes. The nearly identical waveforms without detectable phase delays for a pair of signals along or transverse to the meridian of regions far away from the artery rule out the detectable contribution from the propagation of Qi, some kind of collective excitation which more efficiently propagates along meridians, according to the Chinese medicine theory. Around the radial artery, in addition to the global vibration, the local vibration spectrum shows very slow breathing type vibration around 0.05 Hz, and the artery pulsation induced fundamental and higher harmonics with descending intensities up to the fifth harmonics, standing out of a flat spectrum floor. All the artery pulsation modes are also modulated by respiration and the very slow vibration.

  1. Spatial Distortion of Vibration Modes via Magnetic Correlation of Impurities

    Science.gov (United States)

    Krasniqi, F. S.; Zhong, Y.; Epp, S. W.; Foucar, L.; Trigo, M.; Chen, J.; Reis, D. A.; Wang, H. L.; Zhao, J. H.; Lemke, H. T.; Zhu, D.; Chollet, M.; Fritz, D. M.; Hartmann, R.; Englert, L.; Strüder, L.; Schlichting, I.; Ullrich, J.

    2018-03-01

    Long wavelength vibrational modes in the ferromagnetic semiconductor Ga0.91 Mn0.09 As are investigated using time resolved x-ray diffraction. At room temperature, we measure oscillations in the x-ray diffraction intensity corresponding to coherent vibrational modes with well-defined wavelengths. When the correlation of magnetic impurities sets in, we observe the transition of the lattice into a disordered state that does not support coherent modes at large wavelengths. Our measurements point toward a magnetically induced broadening of long wavelength vibrational modes in momentum space and their quasilocalization in the real space. More specifically, long wavelength vibrational modes cannot be assigned to a single wavelength but rather should be represented as a superposition of plane waves with different wavelengths. Our findings have strong implications for the phonon-related processes, especially carrier-phonon and phonon-phonon scattering, which govern the electrical conductivity and thermal management of semiconductor-based devices.

  2. Raman intensity and vibrational modes of armchair CNTs

    Science.gov (United States)

    Hur, Jaewoong; Stuart, Steven J.

    2017-07-01

    Raman intensity changes and frequency patterns have been studied using the various armchair (n, n) to understand the variations of bond polarizability, in regard to changing diameters, lengths, and the number of atoms in the (n, n). The Raman intensity trends of the (n, n) are validated by those of Cn isomers. For frequency trends, similar frequency patterns and frequency inward shifts for the (n, n) are characterized. Also, VDOS trends of the (n, n) expressing Raman modes are interpreted. The decomposition of vibrational modes in the (n, n) into radial, longitudinal, and tangential mode is beneficially used to recognize the distinct characteristics of vibrational modes.

  3. Vibration modes of a single plate with general boundary conditions

    Directory of Open Access Journals (Sweden)

    Phamová L.

    2016-06-01

    Full Text Available This paper deals with free flexural vibration modes and natural frequencies of a thin plate with general boundary conditions — a simply supported plate connected to its surroundings with torsional springs. Vibration modes were derived on the basis of the Rajalingham, Bhat and Xistris approach. This approach was originally used for a clamped thin plate, so its adaptation was needed. The plate vibration function was usually expressed as a single partial differential equation. This partial differential equation was transformed into two ordinary differential equations that can be solved in the simpler way. Theoretical background of the computations is briefly described. Vibration modes of the supported plate with torsional springs are presented graphically and numerically for three different values of stiffness of torsional springs.

  4. Non-linear vibrational modes in biomolecules: A periodic orbits description

    International Nuclear Information System (INIS)

    Kampanarakis, Alexandros; Farantos, Stavros C.; Daskalakis, Vangelis; Varotsis, Constantinos

    2012-01-01

    Graphical abstract: Vibrational frequency shifts in Fe IV = O species of the active site of cytochrome c oxidase are attributed to changes in the surrounding Coulomb field. Periodic orbits analysis assists to find the most anharmonic modes in model biomolecules. Highlights: ► Periodic orbits are extended to multidimensional potentials of biomolecules. ► Highly anharmonic vibrational modes and center-saddle bifurcations are detected. ► Vibrational frequencies shifts in Oxoferryl species of CcO are observed. - Abstract: The vibrational harmonic normal modes of a molecule, which are valid at energies close to an equilibrium point (a minimum, maximum or saddle of the potential energy surface), are extended by periodic orbits to high energies where anharmonicity and coupling of the degrees of freedom are significant. In this way the assignment of the spectra, and thus the extraction of dynamics in highly excited molecules, can be obtained. New vibrational modes emanating from bifurcations of periodic orbits and long living localized trajectories signal the birth and localization of new quantum states. In this article we review and further study non-linear vibrational modes for model biomolecules such as alanine dipeptide and the active site in the oxoferryl oxidation state of the enzyme cytochrome c oxidase. We locate periodic orbits which exhibit high anhamonicity and lead to center-saddle bifurcations. These modes are associated to an isomerization process in alanine dipeptide and to frequency shifts in the oxoferryl observed by modifying the Coulomb field around the Imidazole–Fe IV = O species.

  5. A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones

    Directory of Open Access Journals (Sweden)

    Yongmeng Zhang

    2015-01-01

    Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  6. Single-molecule electronics: Cooling individual vibrational modes by the tunneling current.

    Science.gov (United States)

    Lykkebo, Jacob; Romano, Giuseppe; Gagliardi, Alessio; Pecchia, Alessandro; Solomon, Gemma C

    2016-03-21

    Electronic devices composed of single molecules constitute the ultimate limit in the continued downscaling of electronic components. A key challenge for single-molecule electronics is to control the temperature of these junctions. Controlling heating and cooling effects in individual vibrational modes can, in principle, be utilized to increase stability of single-molecule junctions under bias, to pump energy into particular vibrational modes to perform current-induced reactions, or to increase the resolution in inelastic electron tunneling spectroscopy by controlling the life-times of phonons in a molecule by suppressing absorption and external dissipation processes. Under bias the current and the molecule exchange energy, which typically results in heating of the molecule. However, the opposite process is also possible, where energy is extracted from the molecule by the tunneling current. Designing a molecular "heat sink" where a particular vibrational mode funnels heat out of the molecule and into the leads would be very desirable. It is even possible to imagine how the vibrational energy of the other vibrational modes could be funneled into the "cooling mode," given the right molecular design. Previous efforts to understand heating and cooling mechanisms in single molecule junctions have primarily been concerned with small models, where it is unclear which molecular systems they correspond to. In this paper, our focus is on suppressing heating and obtaining current-induced cooling in certain vibrational modes. Strategies for cooling vibrational modes in single-molecule junctions are presented, together with atomistic calculations based on those strategies. Cooling and reduced heating are observed for two different cooling schemes in calculations of atomistic single-molecule junctions.

  7. Mechanical detection and mode shape imaging of vibrational modes of micro and nanomechanical resonators by dynamic force microscopy

    International Nuclear Information System (INIS)

    Paulo, A S; GarcIa-Sanchez, D; Perez-Murano, F; Bachtold, A; Black, J; Bokor, J; Esplandiu, M J; Aguasca, A

    2008-01-01

    We describe a method based on the use of higher order bending modes of the cantilever of a dynamic force microscope to characterize vibrations of micro and nanomechanical resonators at arbitrarily large resonance frequencies. Our method consists on using a particular cantilever eigenmode for standard feedback control in amplitude modulation operation while another mode is used for detecting and imaging the resonator vibration. In addition, the resonating sample device is driven at or near its resonance frequency with a signal modulated in amplitude at a frequency that matches the resonance of the cantilever eigenmode used for vibration detection. In consequence, this cantilever mode is excited with an amplitude proportional to the resonator vibration, which is detected with an external lock-in amplifier. We show two different application examples of this method. In the first one, acoustic wave vibrations of a film bulk acoustic resonator around 1.6 GHz are imaged. In the second example, bending modes of carbon nanotube resonators up to 3.1 GHz are characterized. In both cases, the method provides subnanometer-scale sensitivity and the capability of providing otherwise inaccessible information about mechanical resonance frequencies, vibration amplitude values and mode shapes

  8. selective excitation of vibrational modes of polyatomic molecule

    Indian Academy of Sciences (India)

    Abstract. Mode-selective dynamics of triatomic molecule in the electronic ground state under continuous wave laser pulse is investigated for the discrete vibrational bound states. A non-perturbative approach has been used to analyse the vibrational couplings and dynamics of the molecule. Keywords. Polyatomic molecule ...

  9. An ab initio investigation of vibrational, thermodynamic, and optical properties of Sc2AlC MAX compound

    International Nuclear Information System (INIS)

    Ali, M A; Nasir, M T; Khatun, M R; Naqib, S H; Islam, A K M A

    2016-01-01

    The structural vibrational, thermodynamical, and optical properties of potentially technologically important, weakly coupled MAX compound, Sc 2 AlC are calculated using density functional theory (DFT). The structural properties of Sc 2 AlC are compared with the results reported earlier. The vibrational, thermodynamical, and optical properties are theoretically estimated for the first time. The phonon dispersion curve is calculated and the dynamical stability of this compound is investigated. The optical and acoustic modes are observed clearly. We calculate the Helmholtz free energy ( F ), internal energy ( E ), entropy ( S ), and specific heat capacity ( C v ) from the phonon density of states. Various optical parameters are also calculated. The reflectance spectrum shows that this compound has the potential to be used as an efficient solar reflector. (paper)

  10. Accurate mode characterization of two-mode optical fibers by in-fiber acousto-optics.

    Science.gov (United States)

    Alcusa-Sáez, E; Díez, A; Andrés, M V

    2016-03-07

    Acousto-optic interaction in optical fibers is exploited for the accurate and broadband characterization of two-mode optical fibers. Coupling between LP 01 and LP 1m modes is produced in a broadband wavelength range. Difference in effective indices, group indices, and chromatic dispersions between the guided modes, are obtained from experimental measurements. Additionally, we show that the technique is suitable to investigate the fine modes structure of LP modes, and some other intriguing features related with modes' cut-off.

  11. Fiber optic vibration sensor using bifurcated plastic optical fiber

    Science.gov (United States)

    Abdullah, M.; Bidin, N.; Yasin, M.

    2016-11-01

    An extrinsic fiber optic vibration sensor is demonstrated for a fiber optic displacement sensor based on a bundled multimode fiber to measure a vibration frequency ranging from 100 until 3000 Hz. The front slope has a sensitivity of 0.1938mV/mm and linearity of 99.7% within a measurement range between 0.15-3.00 mm. By placing the diaphragm of the concave load-speaker within the linear range from the probe, the frequency of the vibration can be measured with error percentage of less than 1.54%. The graph of input against output frequency for low, medium and high frequency range show very high linearity up to 99%. Slope for low, medium, and high frequency range are calculated as 1.0026, 0.9934, and 1.0007 respectively. Simplicity, long term stability, low power consumption, wide dynamic and frequency ranges, noise reduction, ruggedness, linearity and light weight make it promising alternative to other well-establish methods for vibration frequency measurement.

  12. Damage and failure detection of composites using optical fiber vibration sensor

    International Nuclear Information System (INIS)

    Yang, Y. C.; Han, K. S.

    2001-01-01

    An intensity-based optical fiber vibration sensor is applied to detect and evaluate damages and fiber failure of composites. The optical fiber vibration sensor is constructed by placing two cleaved fiber end, one of which is cantilevered in a hollow glass tube. The movement of the cantilevered section lags behind the rest of the sensor in response to an applied vibration and the amount of light coupled between the two fibers is thereby modulated. Vibration characteristics of the optical fiber vibration sensor are investigated. Surface mounted optical fiber vibration sensor is used in tensile and indentation test. Experimental results show that the optical fiber sensor can detect damages and fiber failure of composites correctly

  13. Customized shaping of vibration modes by acoustic metamaterial synthesis

    Science.gov (United States)

    Xu, Jiawen; Li, Shilong; Tang, J.

    2018-04-01

    Acoustic metamaterials have attractive potential in elastic wave guiding and attenuation over specific frequency ranges. The vast majority of related investigations are on transient waves. In this research we focus on stationary wave manipulation, i.e., shaping of vibration modes. Periodically arranged piezoelectric transducers shunted with inductive circuits are integrated to a beam structure to form a finite-length metamaterial beam. We demonstrate for the first time that, under a given operating frequency of interest, we can facilitate a metamaterial design such that this frequency becomes a natural frequency of the integrated system. Moreover, the vibration mode corresponding to this natural frequency can be customized and shaped to realize tailored/localized response distribution. This is fundamentally different from previous practices of utilizing geometry modification and/or feedback control to achieve mode tailoring. The metamaterial design is built upon the combinatorial effects of the bandgap feature and the effective resonant cavity feature, both attributed to the dynamic characteristics of the metamaterial beam. Analytical investigations based on unit-cell dynamics and modal analysis of the metamaterial beam are presented to reveal the underlying mechanism. Case illustrations are validated by finite element analyses. Owing to the online tunability of circuitry integrated, the proposed mode shaping technique can be online adjusted to fit specific requirements. The customized shaping of vibration modes by acoustic metamaterial synthesis has potential applications in vibration suppression, sensing enhancement and energy harvesting.

  14. Interference between vibration-to-translation and vibration-to-vibration energy transfer modes in diatomic molecules at high collision energies

    International Nuclear Information System (INIS)

    Shin, H.K.

    1983-01-01

    An explicit time dependent approach for simultaneous VT and VV energy transfer in diatom--diatom collisions is explored using the exponential form of ladder operators in the solution of the Schroedinger equation of motion. The collision of two hydrogen molecules is chosen to illustrate the extent of interference between VT and VV modes among various vibrational states. While vibrational energy transfer processes of nominally VT type can be treated with pure VT mode at low collision energies, the intermode coupling is found to be very important at collision energies of several hω. The occurrence of the coupling appears to be nearly universal in vibrational transitions at such energies. Exceptions to the coupling have been discussed

  15. The hydrogen-bond network of water supports propagating optical phonon-like modes.

    Science.gov (United States)

    Elton, Daniel C; Fernández-Serra, Marivi

    2016-01-04

    The local structure of liquid water as a function of temperature is a source of intense research. This structure is intimately linked to the dynamics of water molecules, which can be measured using Raman and infrared spectroscopies. The assignment of spectral peaks depends on whether they are collective modes or single-molecule motions. Vibrational modes in liquids are usually considered to be associated to the motions of single molecules or small clusters. Using molecular dynamics simulations, here we find dispersive optical phonon-like modes in the librational and OH-stretching bands. We argue that on subpicosecond time scales these modes propagate through water's hydrogen-bond network over distances of up to 2 nm. In the long wavelength limit these optical modes exhibit longitudinal-transverse splitting, indicating the presence of coherent long-range dipole-dipole interactions, as in ice. Our results indicate the dynamics of liquid water have more similarities to ice than previously thought.

  16. Optical vibration measurement of mechatronics devices

    Science.gov (United States)

    Yanabe, Shigeo

    1993-09-01

    An optical vibration measuring system which enables to detect both linear and angular displacement of 25 nm and 5 prad was developed. The system is mainly composed of a He-Ne laser, a displacement detecting photo-diode and lenses, and has linear and angular displacement magnification mechanism using two different principles of optical lever. The system was applied to measure vibrational characteristics of magnetic head slider of hard disk drives and to measure stator teeth driving velocities of ultrasonic motor.

  17. Modeling and analysis of circular flexural-vibration-mode piezoelectric transformer.

    Science.gov (United States)

    Huang, Yihua; Huang, Wei

    2010-12-01

    We propose a circular flexural-vibration-mode piezoelectric transformer and perform a theoretical analysis of the transformer. An equivalent circuit is derived from the equations of piezoelectricity and the Hamilton's principle. With this equivalent circuit, the voltage gain ratio, input impedance, and the efficiency of the circular flexural-vibration-mode piezoelectric transformer can be determined. The basic behavior of the transformer is shown by numerical results.

  18. Mode shape and natural frequency identification for seismic analysis from background vibration

    International Nuclear Information System (INIS)

    Bhan, S.; Wozniak, Z.

    1986-02-01

    The feasibility of calculating natural frequencies and mode shapes of major equipment in a CANDU reactor from the measurements of their response to background excitation has been studied. A review of vibration data measured at various locations in CANDU plants shows that structures responded to a combination of random and harmonic background excitation. Amplitude of measured vibration is sufficient to allow meaningful data analysis. Frequency content in the 0 to 50-Hz range, which is of interest for earthquake response, is present in some of the vibration measurements studied. Spectral techniques have been developed for determining the response function of structures from measured vibration response to background excitation. The natural frequencies and mode shapes are then evaluated graphically from the frequency function plots. The methodology has been tested on a simple cantilever beam with known natural frequencies and mode shapes. The comparison between the theoretical and the computed natural frequencies and mode shapes is good for the lower modes. However, better curve-fitting techniques will be required in future, especially for higher modes. Readily available equipment necessary for the measurement of background vibration in a CANDU plant (which is commercially available) has been identified. An experimental program has been proposed to verify the methodology developed in this study. Recommendations are also made to study methods to improve the accuracy of the mode shape and natural frequency prediction

  19. Heavy atom vibrational modes and low-energy vibrational autodetachment in nitromethane anions

    International Nuclear Information System (INIS)

    Thompson, Michael C.; Weber, J. Mathias; Baraban, Joshua H.; Matthews, Devin A.; Stanton, John F.

    2015-01-01

    We report infrared spectra of nitromethane anion, CH 3 NO 2 − , in the region 700–2150 cm −1 , obtained by Ar predissociation spectroscopy and electron detachment spectroscopy. The data are interpreted in the framework of second-order vibrational perturbation theory based on coupled-cluster electronic structure calculations. The modes in the spectroscopic region studied here are mainly based on vibrations involving the heavier atoms; this work complements earlier studies on nitromethane anion that focused on the CH stretching region of the spectrum. Electron detachment begins at photon energies far below the adiabatic electron affinity due to thermal population of excited vibrational states

  20. Optical Control of Mechanical Mode-Coupling within a MoS2 Resonator in the Strong-Coupling Regime.

    Science.gov (United States)

    Liu, Chang-Hua; Kim, In Soo; Lauhon, Lincoln J

    2015-10-14

    Two-dimensional (2-D) materials including graphene and transition metal dichalcogenides (TMDs) are an exciting platform for ultrasensitive force and displacement detection in which the strong light-matter coupling is exploited in the optical control of nanomechanical motion. Here we report the optical excitation and displacement detection of a ∼ 3 nm thick MoS2 resonator in the strong-coupling regime, which has not previously been achieved in 2-D materials. Mechanical mode frequencies can be tuned by more than 12% by optical heating, and they exhibit avoided crossings indicative of strong intermode coupling. When the membrane is optically excited at the frequency difference between vibrational modes, normal mode splitting is observed, and the intermode energy exchange rate exceeds the mode decay rate by a factor of 15. Finite element and analytical modeling quantifies the extent of mode softening necessary to control intermode energy exchange in the strong coupling regime.

  1. Single mode optical fiber vibration sensor: design and development

    Science.gov (United States)

    Alanis-Carranza, L. E.; Alvarez-Chavez, J. A.; Perez-Sanchez, G. G.; Sierra-Calderon, A.; Rodriguez-Novelo, J. C.

    2016-09-01

    This work deals with the design and development of an SMF28-based vibration detector including the fiber segment, the data acquisition via an NI-USB-6212 card, the data processing code in Visual Basic and the signal spectrum obtained via Fourier analysis. The set-up consists of a regulated voltage source at 2.6V, 300mA, which serves as the power source for a 980nm semiconductor laser operating at 150mW which is fiber coupled into a 20m-piece of SMF-28 fiber. Perpendicular to such fiber the perturbations ranged from 1 to 100 kHz, coming from a DC motor at 12 Volts. At the detection stage, a simple analog filter and a commercial photo diode were employed for data acquisition, before a transimpedance amplification stage reconstructed the signal into the National Instruments data acquisition card. At the output, the signals Fourier transformation allows the signal to be displayed in a personal computer. The presentation will include a full electrical and optical characterization of the device and preliminary sensing results, which could be suitable for structural health monitoring applications.

  2. Effective representation of amide III, II, I, and A modes on local vibrational modes: Analysis of ab initio quantum calculation results.

    Science.gov (United States)

    Hahn, Seungsoo

    2016-10-28

    The Hamiltonian matrix for the first excited vibrational states of a protein can be effectively represented by local vibrational modes constituting amide III, II, I, and A modes to simulate various vibrational spectra. Methods for obtaining the Hamiltonian matrix from ab initio quantum calculation results are discussed, where the methods consist of three steps: selection of local vibrational mode coordinates, calculation of a reduced Hessian matrix, and extraction of the Hamiltonian matrix from the Hessian matrix. We introduce several methods for each step. The methods were assessed based on the density functional theory calculation results of 24 oligopeptides with four different peptide lengths and six different secondary structures. The completeness of a Hamiltonian matrix represented in the reduced local mode space is improved by adopting a specific atom group for each amide mode and reducing the effect of ignored local modes. The calculation results are also compared to previous models using C=O stretching vibration and transition dipole couplings. We found that local electric transition dipole moments of the amide modes are mainly bound on the local peptide planes. Their direction and magnitude are well conserved except amide A modes, which show large variation. Contrary to amide I modes, the vibrational coupling constants of amide III, II, and A modes obtained by analysis of a dipeptide are not transferable to oligopeptides with the same secondary conformation because coupling constants are affected by the surrounding atomic environment.

  3. Vibration insensitive interferometry

    Science.gov (United States)

    Millerd, James; Brock, Neal; Hayes, John; Kimbrough, Brad; North-Morris, Michael; Wyant, James C.

    2017-11-01

    The largest limitation of phase-shifting interferometry for optical testing is the sensitivity to the environment, both vibration and air turbulence. An interferometer using temporal phase-shifting is very sensitive to vibration because the various phase shifted frames of interferometric data are taken at different times and vibration causes the phase shifts between the data frames to be different from what is desired. Vibration effects can be reduced by taking all the phase shifted frames simultaneously and turbulence effects can be reduced by averaging many measurements. There are several techniques for simultaneously obtaining several phase-shifted interferograms and this paper will discuss two such techniques: 1) Simultaneous phase-shifting interferometry on a single detector array (PhaseCam) and 2) Micropolarizer phase-shifting array. The application of these techniques for the testing of large optical components, measurement of vibrational modes, the phasing of segmented optical components, and the measurement of deformations of large diffuse structures is described.

  4. Evaluation of Bus Vibration Comfort Based on Passenger Crowdsourcing Mode

    Directory of Open Access Journals (Sweden)

    Hong Zhao

    2016-01-01

    Full Text Available Vibration comfort is an important factor affecting the quality of service (QoS of bus. In order to make people involved in supervising bus’s vibration comfort and improve passengers’ riding experience, a novel mode of passenger crowdsourcing is introduced. In this paper, comfort degree of bus vibration is calculated from bus’s vibration signals collected by passengers’ smartphones and sent through WiFi to the Boa web server which shows the vibration comfort on the LCD deployed in bus and maybe trigger alarm lamp when the vibration is beyond the threshold. Three challenges here have been overcome: firstly, space coordinate transformation algorithm is used to solve the constant drift of signals collected; secondly, a low-pass filter is designed to isolate gravity from signals real-timely via limited computing resources; thirdly, an embedded evaluation system is developed according to the calculation procedure specified by criterion ISO 2631-1997. Meanwhile, the model proposed is tested in a practical running environment, the vibration data in whole travel are recorded and analyzed offline. The results show that comfort degree of vibration obtained from the experimental system is identical with the truth, and this mode is proved to be effective.

  5. Mode-selective vibrational modulation of charge transport in organic electronic devices

    KAUST Repository

    Bakulin, Artem A.

    2015-08-06

    The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials.

  6. Mode-selective vibrational modulation of charge transport in organic electronic devices

    KAUST Repository

    Bakulin, Artem A.; Lovrincic, Robert; Yu, Xi; Selig, Oleg; Bakker, Huib J.; Rezus, Yves L. A.; Nayak, Pabitra K.; Fonari, Alexandr; Coropceanu, Veaceslav; Bredas, Jean-Luc; Cahen, David

    2015-01-01

    The soft character of organic materials leads to strong coupling between molecular, nuclear and electronic dynamics. This coupling opens the way to influence charge transport in organic electronic devices by exciting molecular vibrational motions. However, despite encouraging theoretical predictions, experimental realization of such approach has remained elusive. Here we demonstrate experimentally that photoconductivity in a model organic optoelectronic device can be modulated by the selective excitation of molecular vibrations. Using an ultrafast infrared laser source to create a coherent superposition of vibrational motions in a pentacene/C60 photoresistor, we observe that excitation of certain modes in the 1,500–1,700 cm−1 region leads to photocurrent enhancement. Excited vibrations affect predominantly trapped carriers. The effect depends on the nature of the vibration and its mode-specific character can be well described by the vibrational modulation of intermolecular electronic couplings. This presents a new tool for studying electron–phonon coupling and charge dynamics in (bio)molecular materials.

  7. Failure modes and natural control time for distributed vibrating systems

    International Nuclear Information System (INIS)

    Reid, R.M.

    1994-01-01

    The eigenstructure of the Gram matrix of frequency exponentials is used to study linear vibrating systems of hyperbolic type with distributed control. Using control norm as a practical measure of controllability and the vibrating string as a prototype, it is demonstrated that hyperbolic systems have a natural control time, even when only finitely many modes are excited. For shorter control times there are identifiable control failure modes which can be steered to zero only with very high cost in control norm. Both natural control time and the associated failure modes are constructed for linear fluids, strings, and beams, making note of the essential algorithms and Mathematica code, and displaying results graphically

  8. Local vibrational modes of the water dimer - Comparison of theory and experiment

    Science.gov (United States)

    Kalescky, R.; Zou, W.; Kraka, E.; Cremer, D.

    2012-12-01

    Local and normal vibrational modes of the water dimer are calculated at the CCSD(T)/CBS level of theory. The local H-bond stretching frequency is 528 cm-1 compared to a normal mode stretching frequency of just 143 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to mass coupling, a change in the anharmonicity, and coupling with the local HOH bending modes. The local mode stretching force constant is related to the strength of the H-bond whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the H-bond strength.

  9. Optimal parameters uncoupling vibration modes of oscillators

    Science.gov (United States)

    Le, K. C.; Pieper, A.

    2017-07-01

    This paper proposes a novel optimization concept for an oscillator with two degrees of freedom. By using specially defined motion ratios, we control the action of springs to each degree of freedom of the oscillator. We aim at showing that, if the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized among all admissible parameters and motions satisfying Lagrange's equations, then the optimal motion ratios uncouple vibration modes. A similar result holds true for the dissipative oscillator having dampers. The application to optimal design of vehicle suspension is discussed.

  10. Even nanomechanical modes transduced by integrated photonics

    Energy Technology Data Exchange (ETDEWEB)

    Westwood-Bachman, J. N.; Diao, Z.; Sauer, V. T. K.; Hiebert, W. K., E-mail: wayne.hiebert@nrc-cnrc.gc.ca [Department of Physics, University of Alberta, Edmonton T6G 2E1 (Canada); National Institute for Nanotechnology, 11421 Saskatchewan Drive, Edmonton T6G 2M9 (Canada); Bachman, D. [Department of Electrical Engineering, University of Alberta, Edmonton T6G 2V4 (Canada)

    2016-02-08

    We demonstrate the actuation and detection of even flexural vibrational modes of a doubly clamped nanomechanical resonator using an integrated photonics transduction scheme. The doubly clamped beam is formed by releasing a straight section of an optical racetrack resonator from the underlying silicon dioxide layer, and a step is fabricated in the substrate beneath the beam. The step causes uneven force and responsivity distribution along the device length, permitting excitation and detection of even modes of vibration. This is achieved while retaining transduction capability for odd modes. The devices are actuated via optical force applied with a pump laser. The displacement sensitivities of the first through third modes, as obtained from the thermomechanical noise floor, are 228 fm Hz{sup −1/2}, 153 fm Hz{sup −1/2}, and 112 fm Hz{sup −1/2}, respectively. The excitation efficiency for these modes is compared and modeled based on integration of the uneven forces over the mode shapes. While the excitation efficiency for the first three modes is approximately the same when the step occurs at about 38% of the beam length, the ability to tune the modal efficiency of transduction by choosing the step position is discussed. The overall optical force on each mode is approximately 0.4 pN μm{sup −1} mW{sup −1}, for an applied optical power of 0.07 mW. We show a potential application that uses the resonant frequencies of the first two vibrational modes of a buckled beam to measure the stress in the silicon device layer, estimated to be 106 MPa. We anticipate that the observation of the second mode of vibration using our integrated photonics approach will be useful in future mass sensing experiments.

  11. First international conference on vibration control in optics and metrology

    International Nuclear Information System (INIS)

    Baker, L.R.

    1987-01-01

    This book contains 27 selections. Some of the titles are: Use of optics for vibration analysis of automotive components; Use of pulsed lasers for vibration analysis in the nuclear power industry; Vibration analysis of photocopiers; Control of ground vibrations; Design of low-vibration buildings: two case histories; and Continuous pulsed electronic speckle pattern interferometry

  12. Vocal fold contact patterns based on normal modes of vibration.

    Science.gov (United States)

    Smith, Simeon L; Titze, Ingo R

    2018-05-17

    The fluid-structure interaction and energy transfer from respiratory airflow to self-sustained vocal fold oscillation continues to be a topic of interest in vocal fold research. Vocal fold vibration is driven by pressures on the vocal fold surface, which are determined by the shape of the glottis and the contact between vocal folds. Characterization of three-dimensional glottal shapes and contact patterns can lead to increased understanding of normal and abnormal physiology of the voice, as well as to development of improved vocal fold models, but a large inventory of shapes has not been directly studied previously. This study aimed to take an initial step toward characterizing vocal fold contact patterns systematically. Vocal fold motion and contact was modeled based on normal mode vibration, as it has been shown that vocal fold vibration can be almost entirely described by only the few lowest order vibrational modes. Symmetric and asymmetric combinations of the four lowest normal modes of vibration were superimposed on left and right vocal fold medial surfaces, for each of three prephonatory glottal configurations, according to a surface wave approach. Contact patterns were generated from the interaction of modal shapes at 16 normalized phases during the vibratory cycle. Eight major contact patterns were identified and characterized by the shape of the flow channel, with the following descriptors assigned: convergent, divergent, convergent-divergent, uniform, split, merged, island, and multichannel. Each of the contact patterns and its variation are described, and future work and applications are discussed. Copyright © 2018 Elsevier Ltd. All rights reserved.

  13. True Tapping Mode Scanning Near-Field Optical Microscopy with Bent Glass Fiber Probes.

    Science.gov (United States)

    Smirnov, A; Yasinskii, V M; Filimonenko, D S; Rostova, E; Dietler, G; Sekatskii, S K

    2018-01-01

    In scanning near-field optical microscopy, the most popular probes are made of sharpened glass fiber attached to a quartz tuning fork (TF) and exploiting the shear force-based feedback. The use of tapping mode feedback could be preferable. Such an approach can be realized, for example, using bent fiber probes. Detailed analysis of fiber vibration modes shows that realization of truly tapping mode of the probe dithering requires an extreme caution. In case of using the second resonance mode, probes vibrate mostly in shear force mode unless the bending radius is rather small (ca. 0.3 mm) and the probe's tip is short. Otherwise, the shear force character of the dithering persists. Probes having these characteristics were prepared by irradiation of a tapered etched glass fiber with a CW CO 2 laser. These probes were attached to the TF in double resonance conditions which enables achieving significant quality factor (4000-6000) of the TF + probe system (Cherkun et al., 2006). We also show that, to achieve a truly tapping character, dithering, short, and not exceeding 3 mm lengths of a freestanding part of bent fiber probe beam should also be used in the case of nonresonant excitation.

  14. True Tapping Mode Scanning Near-Field Optical Microscopy with Bent Glass Fiber Probes

    Directory of Open Access Journals (Sweden)

    A. Smirnov

    2018-01-01

    Full Text Available In scanning near-field optical microscopy, the most popular probes are made of sharpened glass fiber attached to a quartz tuning fork (TF and exploiting the shear force-based feedback. The use of tapping mode feedback could be preferable. Such an approach can be realized, for example, using bent fiber probes. Detailed analysis of fiber vibration modes shows that realization of truly tapping mode of the probe dithering requires an extreme caution. In case of using the second resonance mode, probes vibrate mostly in shear force mode unless the bending radius is rather small (ca. 0.3 mm and the probe’s tip is short. Otherwise, the shear force character of the dithering persists. Probes having these characteristics were prepared by irradiation of a tapered etched glass fiber with a CW CO2 laser. These probes were attached to the TF in double resonance conditions which enables achieving significant quality factor (4000–6000 of the TF + probe system (Cherkun et al., 2006. We also show that, to achieve a truly tapping character, dithering, short, and not exceeding 3 mm lengths of a freestanding part of bent fiber probe beam should also be used in the case of nonresonant excitation.

  15. Precise Ab-initio prediction of terahertz vibrational modes in crystalline systems

    DEFF Research Database (Denmark)

    Jepsen, Peter Uhd; Clark, Stewart J.

    2007-01-01

    We use a combination of experimental THz time-domain spectroscopy and ab-initio density functional perturbative theory to accurately predict the terahertz vibrational spectrum of molecules in the crystalline phase. Our calculations show that distinct vibrational modes found in solid-state materials...

  16. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    International Nuclear Information System (INIS)

    Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

    2011-01-01

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  17. Tailoring vibration mode shapes using topology optimization and functionally graded material concepts

    International Nuclear Information System (INIS)

    Rubio, Wilfredo Montealegre; Paulino, Glaucio H; Silva, Emilio Carlos Nelli

    2011-01-01

    Tailoring specified vibration modes is a requirement for designing piezoelectric devices aimed at dynamic-type applications. A technique for designing the shape of specified vibration modes is the topology optimization method (TOM) which finds an optimum material distribution inside a design domain to obtain a structure that vibrates according to specified eigenfrequencies and eigenmodes. Nevertheless, when the TOM is applied to dynamic problems, the well-known grayscale or intermediate material problem arises which can invalidate the post-processing of the optimal result. Thus, a more natural way for solving dynamic problems using TOM is to allow intermediate material values. This idea leads to the functionally graded material (FGM) concept. In fact, FGMs are materials whose properties and microstructure continuously change along a specific direction. Therefore, in this paper, an approach is presented for tailoring user-defined vibration modes, by applying the TOM and FGM concepts to design functionally graded piezoelectric transducers (FGPT) and non-piezoelectric structures (functionally graded structures—FGS) in order to achieve maximum and/or minimum vibration amplitudes at certain points of the structure, by simultaneously finding the topology and material gradation function. The optimization problem is solved by using sequential linear programming. Two-dimensional results are presented to illustrate the method

  18. Spindle vibration and sound field measurement using optical vibrometry

    OpenAIRE

    Tatar, Kourosh

    2008-01-01

    Mechanical systems often produce a considerable amount of vibration and noise. To be able to obtain a complete picture of the dynamic behaviour of these systems, vibration and sound measurements are of significant importance. Optical metrology is well-suited for non-intrusive measurements on complex objects. The development and the use of remote non-contact vibration measurement methods for spindles are described and vibration measurements on thin- walled structures and sound field measuremen...

  19. Experiments on vibration control of a piezoelectric laminated paraboloidal shell

    Science.gov (United States)

    Yue, Honghao; Lu, Yifan; Deng, Zongquan; Tzou, Hornsen

    2017-01-01

    A paraboloidal shell plays a key role in aerospace and optical structural systems applied to large optical reflector, communications antenna, rocket fairing, missile radome, etc. Due to the complexity of analytical procedures, an experimental study of active vibration control of a piezoelectric laminated paraboloidal shell by positive position feedback is carried out. Sixteen PVDF patches are laminated inside and outside of the shell, in which eight of them are used as sensors and eight as actuators to control the vibration of the first two natural modes. Lower natural frequencies and vibration modes of the paraboloidal shell are obtained via the frequency response function analysis by Modal VIEW software. A mathematical model of the control system is formulated by means of parameter identification. The first shell mode is controlled as well as coupled the first and second modes based on the positive position feedback (PPF) algorithm. To minimize the control energy consumption in orbit, an adaptive modal control method is developed in this study by using the PPF in laboratory experiments. The control system collects vibration signals from the piezoelectric sensors to identify location(s) of the largest vibration amplitudes and then select the best two from eight PVDF actuators to apply control forces so that the modal vibration suppression could be accomplished adaptively and effectively.

  20. Two mode optical fiber in space optics communication

    Science.gov (United States)

    Hampl, Martin

    2017-11-01

    In our contribution we propose to use of a two-mode optical fiber as a primary source in a transmitting optical head instead of the laser diode. The distribution of the optical intensity and the complex degree of the coherence on the output aperture of the lens that is irradiated by a step-index weakly guiding optical fiber is investigated. In our treatment we take into account weakly guided modes with polarization corrections to the propagation constant and unified theory of second order coherence and polarization of electromagnetic beams.

  1. Optical Calibration Process Developed for Neural-Network-Based Optical Nondestructive Evaluation Method

    Science.gov (United States)

    Decker, Arthur J.

    2004-01-01

    A completely optical calibration process has been developed at Glenn for calibrating a neural-network-based nondestructive evaluation (NDE) method. The NDE method itself detects very small changes in the characteristic patterns or vibration mode shapes of vibrating structures as discussed in many references. The mode shapes or characteristic patterns are recorded using television or electronic holography and change when a structure experiences, for example, cracking, debonds, or variations in fastener properties. An artificial neural network can be trained to be very sensitive to changes in the mode shapes, but quantifying or calibrating that sensitivity in a consistent, meaningful, and deliverable manner has been challenging. The standard calibration approach has been difficult to implement, where the response to damage of the trained neural network is compared with the responses of vibration-measurement sensors. In particular, the vibration-measurement sensors are intrusive, insufficiently sensitive, and not numerous enough. In response to these difficulties, a completely optical alternative to the standard calibration approach was proposed and tested successfully. Specifically, the vibration mode to be monitored for structural damage was intentionally contaminated with known amounts of another mode, and the response of the trained neural network was measured as a function of the peak-to-peak amplitude of the contaminating mode. The neural network calibration technique essentially uses the vibration mode shapes of the undamaged structure as standards against which the changed mode shapes are compared. The published response of the network can be made nearly independent of the contaminating mode, if enough vibration modes are used to train the net. The sensitivity of the neural network can be adjusted for the environment in which the test is to be conducted. The response of a neural network trained with measured vibration patterns for use on a vibration isolation

  2. Nonplanar tertiary amides in rigid chiral tricyclic dilactams. Peptide group distortions and vibrational optical activity.

    Science.gov (United States)

    Pazderková, Markéta; Profant, Václav; Hodačová, Jana; Sebestík, Jaroslav; Pazderka, Tomáš; Novotná, Pavlína; Urbanová, Marie; Safařík, Martin; Buděšínský, Miloš; Tichý, Miloš; Bednárová, Lucie; Baumruk, Vladimír; Maloň, Petr

    2013-08-22

    We investigate amide nonplanarity in vibrational optical activity (VOA) spectra of tricyclic spirodilactams 5,8-diazatricyclo[6,3,0,0(1,5)]undecan-4,9-dione (I) and its 6,6',7,7'-tetradeuterio derivative (II). These rigid molecules constrain amide groups to nonplanar geometries with twisted pyramidal arrangements of bonds to amide nitrogen atoms. We have collected a full range vibrational circular dichroism (VCD) and Raman optical activity (ROA) spectra including signals of C-H and C-D stretching vibrations. We report normal-mode analysis and a comparison of calculated to experimental VCD and ROA. The data provide band-to-band assignment and offer a possibility to evaluate roles of constrained nonplanar tertiary amide groups and rigid chiral skeletons. Nonplanarity shows as single-signed VCD and ROA amide I signals, prevailing the couplets expected to arise from the amide-amide interaction. Amide-amide coupling dominates amide II (mainly C'-N stretching, modified in tertiary amides by the absence of a N-H bond) transitions (strong couplet in VCD, no significant ROA) probably due to the close proximity of amide nitrogen atoms. At lower wavenumbers, ROA spectra exhibit another likely manifestation of amide nonplanarity, showing signals of amide V (δ(oop)(N-C) at ~570 cm(-1)) and amide VI (δ(oop)(C'═O) at ~700 cm(-1) and ~650 cm(-1)) vibrations.

  3. A Pictorial Visualization of Normal Mode Vibrations of the Fullerene (C[subscript 60]) Molecule in Terms of Vibrations of a Hollow Sphere

    Science.gov (United States)

    Dunn, Janette L.

    2010-01-01

    Understanding the normal mode vibrations of a molecule is important in the analysis of vibrational spectra. However, the complicated 3D motion of large molecules can be difficult to interpret. We show how images of normal modes of the fullerene molecule C[subscript 60] can be made easier to understand by superimposing them on images of the normal…

  4. Distributed Fiber-Optic Sensor for Detection and Localization of Acoustic Vibrations

    Directory of Open Access Journals (Sweden)

    Sifta Radim

    2015-03-01

    Full Text Available A sensing system utilizing a standard optical fiber as a distributed sensor for the detection and localization of mechanical vibrations is presented. Vibrations can be caused by various external factors, like moving people, cars, trains, and other objects producing mechanical vibrations that are sensed by a fiber. In our laboratory we have designed a sensing system based on the Φ-OTDR (phase sensitive Optical Time Domain Reflectometry using an extremely narrow laser and EDFAs.

  5. VCD Robustness of the Amide-I and Amide-II Vibrational Modes of Small Peptide Models.

    Science.gov (United States)

    Góbi, Sándor; Magyarfalvi, Gábor; Tarczay, György

    2015-09-01

    The rotational strengths and the robustness values of amide-I and amide-II vibrational modes of For(AA)n NHMe (where AA is Val, Asn, Asp, or Cys, n = 1-5 for Val and Asn; n = 1 for Asp and Cys) model peptides with α-helix and β-sheet backbone conformations were computed by density functional methods. The robustness results verify empirical rules drawn from experiments and from computed rotational strengths linking amide-I and amide-II patterns in the vibrational circular dichroism (VCD) spectra of peptides with their backbone structures. For peptides with at least three residues (n ≥ 3) these characteristic patterns from coupled amide vibrational modes have robust signatures. For shorter peptide models many vibrational modes are nonrobust, and the robust modes can be dependent on the residues or on their side chain conformations in addition to backbone conformations. These robust VCD bands, however, provide information for the detailed structural analysis of these smaller systems. © 2015 Wiley Periodicals, Inc.

  6. Intermediate energy electron impact excitation of composite vibrational modes in phenol

    Energy Technology Data Exchange (ETDEWEB)

    Neves, R. F. C. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Instituto Federal do Sul de Minas Gerais, Campus Poços de Caldas, Minas Gerais (Brazil); Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Lopes, M. C. A.; Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-900, Juiz de Fora, Minas Gerais (Brazil); Oliveira, E. M. de; Lima, M. A. P. [Instituto de Física ‘Gleb Wataghin,’ Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo (Brazil); Costa, R. F. da [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, 09210-580 Santo André, São Paulo (Brazil); Varella, M. T. do N. [Instituto de Física, Universidade de São Paulo, C.P. 66318, 05315-970 São Paulo (Brazil); Bettega, M. H. F. [Departamento de Física, Universidade Federal do Paraná, C.P. 19044, 81531-990 Curitiba, Paraná (Brazil); Silva, G. B. da [Universidade Federal de Mato Grosso, Barra do Garças, Mato Grosso (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, G.P.O. Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-05-21

    We report differential cross section results from an experimental investigation into the electron impact excitation of a number of the low-lying composite (unresolved) vibrational modes in phenol (C{sub 6}H{sub 5}OH). The measurements were carried out at incident electron energies in the range 15–40 eV and for scattered-electron angles in the range 10–90°. The energy resolution of those measurements was typically ∼80 meV. Calculations, using the GAMESS code, were also undertaken with a B3LYP/aug-cc-pVDZ level model chemistry, in order to enable us to assign vibrational modes to the features observed in our energy loss spectra. To the best of our knowledge, the present cross sections are the first to be reported for vibrational excitation of the C{sub 6}H{sub 5}OH molecule by electron impact.

  7. Nonlinear laser dynamics induced by frequency shifted optical feedback: application to vibration measurements.

    Science.gov (United States)

    Girardeau, Vadim; Goloni, Carolina; Jacquin, Olivier; Hugon, Olivier; Inglebert, Mehdi; Lacot, Eric

    2016-12-01

    In this article, we study the nonlinear dynamics of a laser subjected to frequency shifted optical reinjection coming back from a vibrating target. More specifically, we study the nonlinear dynamical coupling between the carrier and the vibration signal. The present work shows how the nonlinear amplification of the vibration spectrum is related to the strength of the carrier and how it must be compensated to obtain accurate (i.e., without bias) vibration measurements. The theoretical predictions, confirmed by numerical simulations, are in good agreement with the experimental data. The main motivation of this study is the understanding of the nonlinear response of a laser optical feedback imaging sensor for quantitative phase measurements of small vibrations in the case of strong optical feedback.

  8. Ab-initio study of structural, vibrational and optical properties of solid oxidizers

    Energy Technology Data Exchange (ETDEWEB)

    Yedukondalu, N.; Vaitheeswaran, G., E-mail: gvsp@uohyd.ernet.in

    2016-09-15

    We report the structural, elastic and vibrational properties of five ionic-molecular solid oxidizers MNO{sub 3} (M = Li, Na, K) and MClO{sub 3} (M = Na, K). By treating long range electron-correlation effects, dispersion corrected method leads to more accurate predictions of structural properties and phase stability of KNO{sub 3} polymorphs. The obtained elastic moduli show soft nature of these materials and are consistent with Ultrasonic Pulse Echo measurements. We made a complete assignment of vibrational modes which are in good accord with available experimental results. From calculated IR and Raman spectra, it is found that the vibrational frequencies show a red-shift from Li → Na → K (Na → K) and N → Cl for nitrates (chlorates) due to increase in mass of metal and non-metal atoms, respectively. The calculated electronic structure using recently developed Tran-Blaha modified Becke-Johnson potential show that the materials are wide band gap insulators with predominant ionic bonding between M{sup +} (metal) and NO{sub 3}{sup −}/ClO{sub 3}{sup −} ions and covalent bonding (N−O and Cl−O) within nitrate and chlorate anionic group. From the calculated optical spectra, we observe that electric-dipole transitions are due to nitrate/chlorate group below 20 eV and cationic transitions occur above 20 eV. The calculated reflectivity spectra are consistent with the available experimental measurements. - Highlights: • Ground state properties with inclusion of dispersion correction method. • Elastic constants and mechanical properties. • Vibrational spectra and their complete assignment. • Raman and IR spectra. • Electronic structure and optical properties using TB-mBJ potential.

  9. Efficient {pi} electrons delocalization in prospective push-pull non-linear optical chromophore 4-[N,N-dimethylamino]-4'-nitro stilbene (DANS): A vibrational spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, T.; Hubert Joe, I. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695 015, Kerala (India); Reghunadhan Nair, C.P. [Polymers and Special Chemicals Division, Vikram Sarabhai Space Centre, Thiruvananthapuram 695 022, Kerala (India); Jayakumar, V.S. [Centre for Molecular and Biophysics Research, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695 015, Kerala (India)], E-mail: vsjk@vsnl.net

    2008-01-22

    A comprehensive investigation on the intramolecular charge transfer (ICT) of an efficient {pi}-conjugated potential push-pull NLO chromophore, 4-[N,N-dimethylamino]-4'-nitro stilbene (DANS), from a strong electron-donor group (dimethylamino-N(CH{sub 3}){sub 2}) to a strong electron-acceptor group (nitro-NO{sub 2}) through the {pi}-conjugated bridge (trans-stilbene) has been carried out from their vibrational spectra. The NIR FT-Raman and FT-IR spectra supported by the density functional theory (DFT) quantum chemical computations have been employed to analyze the effects of intramolecular charge transfer on the geometries and the vibrational modes contributing to the linear electro-optic effect of the organic NLO material. It has been observed that the changes in the endocyclic and exocyclic angles result from the charge-transfer interaction of the phenyl ring and the amino group in the electron-donor side of the NLO chromophore. The strongest vibrational modes contributing to the electro-optic effect have been identified and examined from the concurrent IR and Raman activation of {nu}(C=C/C-C) mode, ring C=C stretching modes, in-plane deformation modes, nitro modes and the umbrella mode of methyl groups. Furthermore, the splitting of the vinyl stretching modes and the electronic effects such as hyperconjugation and backdonation on the methyl hydrogen atoms causing the decrease of stretching frequencies and infrared intensities have also been analyzed in detail. The effect of frontier orbitals transition of electron density transfer and the influence of planarity between the phenyl rings of the stilbene moiety on the first hyperpolarizability have also been discussed.

  10. Hybrid PD and effective multi-mode positive position feedback control for slewing and vibration suppression of a smart flexible manipulator

    International Nuclear Information System (INIS)

    Lou, Jun-qiang; Wei, Yan-ding; Yang, Yi-ling; Xie, Feng-ran

    2015-01-01

    A hybrid control strategy for slewing and vibration suppression of a smart flexible manipulator is presented in this paper. It consists of a proportional derivative controller to realize motion control, and an effective multi-mode positive position feedback (EMPPF) controller to suppress the multi-mode vibration. Rather than treat each mode equally as the standard multi-mode PPF, the essence of the EMPPF is that control forces of different modes are applied according to the mode parameters of the respective modes, so the vibration modes with less vibration energy receive fewer control forces. Stability conditions for the close loop system are established through stability analysis. Optimal parameters of the EMPPF controller are obtained using the method of root locus analysis. The performance of the proposed strategy is demonstrated by simulation and experiments. Experimental results show that the first two vibration modes of the manipulator are effectively suppressed. The setting time of the setup descends approximately 55%, reaching 3.12 s from 5.67 s. (paper)

  11. Hybrid PD and effective multi-mode positive position feedback control for slewing and vibration suppression of a smart flexible manipulator

    Science.gov (United States)

    Lou, Jun-qiang; Wei, Yan-ding; Yang, Yi-ling; Xie, Feng-ran

    2015-03-01

    A hybrid control strategy for slewing and vibration suppression of a smart flexible manipulator is presented in this paper. It consists of a proportional derivative controller to realize motion control, and an effective multi-mode positive position feedback (EMPPF) controller to suppress the multi-mode vibration. Rather than treat each mode equally as the standard multi-mode PPF, the essence of the EMPPF is that control forces of different modes are applied according to the mode parameters of the respective modes, so the vibration modes with less vibration energy receive fewer control forces. Stability conditions for the close loop system are established through stability analysis. Optimal parameters of the EMPPF controller are obtained using the method of root locus analysis. The performance of the proposed strategy is demonstrated by simulation and experiments. Experimental results show that the first two vibration modes of the manipulator are effectively suppressed. The setting time of the setup descends approximately 55%, reaching 3.12 s from 5.67 s.

  12. Mode conversion efficiency to Laguerre-Gaussian OAM modes using spiral phase optics.

    Science.gov (United States)

    Longman, Andrew; Fedosejevs, Robert

    2017-07-24

    An analytical model for the conversion efficiency from a TEM 00 mode to an arbitrary Laguerre-Gaussian (LG) mode with null radial index spiral phase optics is presented. We extend this model to include the effects of stepped spiral phase optics, spiral phase optics of non-integer topological charge, and the reduction in conversion efficiency due to broad laser bandwidth. We find that through optimization, an optimal beam waist ratio of the input and output modes exists and is dependent upon the output azimuthal mode number.

  13. Terahertz cross-phase modulation of an optical mode

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Novitsky, Andrey; Zalkovskij, Maksim

    2013-01-01

    We discuss an optical scheme which facilitates modulation of an optical waveguide mode by metallic-nanoslit-enhanced THz radiation. The waveguide mode acquires an additional phase shift due to THz nonlinearity with fields reachable in experiments.......We discuss an optical scheme which facilitates modulation of an optical waveguide mode by metallic-nanoslit-enhanced THz radiation. The waveguide mode acquires an additional phase shift due to THz nonlinearity with fields reachable in experiments....

  14. Optical-domain Compensation for Coupling between Optical Fiber Conjugate Vortex Modes

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir S.; Tatarczak, Anna; Lu, Xiaofeng

    2016-01-01

    We demonstrate for the first time optical-domain compensation for coupling between conjugate vortex modes in optical fibers. We introduce a novel method for reconstructing the complex propagation matrix of the optical fiber with straightforward implementation.......We demonstrate for the first time optical-domain compensation for coupling between conjugate vortex modes in optical fibers. We introduce a novel method for reconstructing the complex propagation matrix of the optical fiber with straightforward implementation....

  15. Vibrational mode and sound radiation of electrostatic speakers using circular and annular diaphragms

    Science.gov (United States)

    Huang, Yu-Hsi; Chiang, Hsin-Yuan

    2016-06-01

    This study modeled two diaphragms comprising a pair of indium tin oxide (ITO) transparent plates sandwiching a vibrating diaphragm to create circular (30 mm radius) and annular (30 mm outer and 3 mm inner radius) push-pull electrostatic speakers. We then measured the displacement amplitudes and mode shapes produced by the devices. Vibration characteristics were used to predict sound pressure levels (SPLs) using the lumped parameter method (LPM) and distributed parameter method (DPM). The two measurement results obtained using a laser system were compared to the SPLs obtained using traditional acoustic measurement (AM) from 20 Hz to 20 kHz in order to verify our predictions. When using LPM and DPM, the SPL prediction results in the first three symmetric modes were in good agreement with the AM results. Under the assumption of linear operations, the DPM and amplitude-fluctuation electronic speckle pattern interferometry (ESPI) techniques proved effective in determining the visualization of mode shape (0,1)-(0,3). The use of ITO plates is a practical technique for the prediction of SPL, as well as measurement of mode shapes. The four evaluation methods, i.e. LPM, DPM, ESPI and AM, present a high degree of consistency with regard to vibrational mode and sound radiation characteristics.

  16. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We...

  17. Vibrational modes of deuterium in KD2PO4

    International Nuclear Information System (INIS)

    Mizoguchi, Kohji; Agui, Akane; Tominaga, Yasunori; Nakai, Yusuke; Ikeda, Susumu.

    1993-01-01

    In order to study the deuteration effect in hydrogen-bonded compounds such as KH 2 PO 4 , hydrogen and deuterium modes in KH 2 PO 4 and K(D x H 1-x ) 2 PO 4 (x = 95 %) were investigated by means of inelastic neutron-scattering measurements over a wide energy range. By comparing Raman spectra of KH 2 PO 4 and KD 2 PO 4 with neutron-scattering spectra, the vibrational modes of deuterium and those of PO 4 tetrahedrons in the energy range of 30 < ε < 150 meV have been investigated. At least two deuterium modes have been found at 87 meV and 106 meV. (author)

  18. Investigations on structural, vibrational, morphological and optical properties of CdS and CdS/Co films by ultrasonic spray pyrolysis

    International Nuclear Information System (INIS)

    Aksay, S.; Polat, M.; Ozer, T.; Koese, S.; Guerbuez, G.

    2011-01-01

    CdS and CdS/Co films have been deposited on glass substrates by an ultrasonic spray pyrolysis method. The effects of Co incorporation on the structural, optical, morphological, elemental and vibrational properties of these films were investigated. XRD analysis confirmed the hexagonal wurtzite structure of all films and had no impurity phase. While CdS film has (0 0 2) as the preferred orientation, CdS/Co films have (1 1 0) as the preferred orientation. The direct optical band gap was found to decrease from 2.42 to 2.39 eV by Co incorporation. The decrease of the direct energy gaps by increasing Co contents is mainly due to the sp-d exchange interaction between the localized d-electrons of Co 2+ ions and band electrons of CdS. After the optical investigations, it was seen that the transmittance of CdS films decreased by Co content. The Raman measurements revealed two peaks corresponding to the 1LO and 2LO modes of hexagonal CdS. The vibrational modes of Cd-S were obtained in the wavenumber range (590-715 cm -1 ) using Fourier transform infrared spectroscopy (FTIR). The elemental analysis of the film was done by energy dispersive X-ray spectrometry.

  19. Investigations on structural, vibrational, morphological and optical properties of CdS and CdS/Co films by ultrasonic spray pyrolysis

    Science.gov (United States)

    Aksay, S.; Polat, M.; Özer, T.; Köse, S.; Gürbüz, G.

    2011-09-01

    CdS and CdS/Co films have been deposited on glass substrates by an ultrasonic spray pyrolysis method. The effects of Co incorporation on the structural, optical, morphological, elemental and vibrational properties of these films were investigated. XRD analysis confirmed the hexagonal wurtzite structure of all films and had no impurity phase. While CdS film has (0 0 2) as the preferred orientation, CdS/Co films have (1 1 0) as the preferred orientation. The direct optical band gap was found to decrease from 2.42 to 2.39 eV by Co incorporation. The decrease of the direct energy gaps by increasing Co contents is mainly due to the sp-d exchange interaction between the localized d-electrons of Co2+ ions and band electrons of CdS. After the optical investigations, it was seen that the transmittance of CdS films decreased by Co content. The Raman measurements revealed two peaks corresponding to the 1LO and 2LO modes of hexagonal CdS. The vibrational modes of Cd-S were obtained in the wavenumber range (590-715 cm-1) using Fourier transform infrared spectroscopy (FTIR). The elemental analysis of the film was done by energy dispersive X-ray spectrometry.

  20. Rayleigh scattering in few-mode optical fibers.

    Science.gov (United States)

    Wang, Zhen; Wu, Hao; Hu, Xiaolong; Zhao, Ningbo; Mo, Qi; Li, Guifang

    2016-10-24

    The extremely low loss of silica fibers has enabled the telecommunication revolution, but single-mode fiber-optic communication systems have been driven to their capacity limits. As a means to overcome this capacity crunch, space-division multiplexing (SDM) using few-mode fibers (FMF) has been proposed and demonstrated. In single-mode optical fibers, Rayleigh scattering serves as the dominant mechanism for optical loss. However, to date, the role of Rayleigh scattering in FMFs remains elusive. Here we establish and experimentally validate a general model for Rayleigh scattering in FMFs. Rayleigh backscattering not only sets the intrinsic loss limit for FMFs but also provides the theoretical foundation for few-mode optical time-domain reflectometry, which can be used to probe perturbation-induced mode-coupling dynamics in FMFs. We also show that forward inter-modal Rayleigh scattering ultimately sets a fundamental limit on inter-modal-crosstalk for FMFs. Therefore, this work not only has implications specifically for SDM systems but also broadly for few-mode fiber optics and its applications in amplifiers, lasers, and sensors in which inter-modal crosstalk imposes a fundamental performance limitation.

  1. Ultrafast vibrations of gold nanorings

    DEFF Research Database (Denmark)

    Kelf, T; Tanaka, Y; Matsuda, O

    2011-01-01

    We investigate the vibrational modes of gold nanorings on a silica substrate with an ultrafast optical technique. By comparison with numerical simulations, we identify several resonances in the gigahertz range associated with axially symmetric deformations of the nanoring and substrate. We elucid...

  2. Localized Surface Plasmons in Vibrating Graphene Nanodisks

    DEFF Research Database (Denmark)

    Wang, Weihua; Li, Bo-Hong; Stassen, Erik

    2016-01-01

    in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined...... by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters...

  3. Vibration Control of Flexible Mode for a Beam-Type Substrate Transport Robot

    Directory of Open Access Journals (Sweden)

    Cheol Hoon Park

    2013-07-01

    Full Text Available Beam-type substrate transport robots are widely used to handle substrates, especially in the solar cell manufacturing process. To reduce the takt time and increase productivity, accurate position control becomes increasingly important as the size of the substrate increases. However, the vibration caused by the flexible forks in beam-type robots interferes with accurate positioning, which results in long takt times in the manufacturing process. To minimize the vibration and transport substrates on the fork as fast as possible, the trajectories should be prevented from exciting the flexible modes of the forks. For this purpose, a fifth-order polynomial trajectory generator and input shaping were incorporated into the controller of the beam-type robot in this study. The flexible modes of the forks were identified by measuring the frequency response function (FRF, and the input shaping was designed so as not to excite the flexible modes. The controller was implemented by using MATLAB/xPC Target. In this paper, the design procedure of input shaping and its effectiveness for vibration attenuation in both “no load” and “load” cases is presented.

  4. Vibrational Surface Electron-Energy-Loss Spectroscopy Probes Confined Surface-Phonon Modes

    Directory of Open Access Journals (Sweden)

    Hugo Lourenço-Martins

    2017-12-01

    Full Text Available Recently, two reports [Krivanek et al. Nature (London 514, 209 (2014NATUAS0028-083610.1038/nature13870, Lagos et al. Nature (London 543, 529 (2017NATUAS0028-083610.1038/nature21699] have demonstrated the amazing possibility to probe vibrational excitations from nanoparticles with a spatial resolution much smaller than the corresponding free-space phonon wavelength using electron-energy-loss spectroscopy (EELS. While Lagos et al. evidenced a strong spatial and spectral modulation of the EELS signal over a nanoparticle, Krivanek et al. did not. Here, we show that discrepancies among different EELS experiments as well as their relation to optical near- and far-field optical experiments [Dai et al. Science 343, 1125 (2014SCIEAS0036-807510.1126/science.1246833] can be understood by introducing the concept of confined bright and dark surface phonon modes, whose density of states is probed by EELS. Such a concise formalism is the vibrational counterpart of the broadly used formalism for localized surface plasmons [Ouyang and Isaacson Philos. Mag. B 60, 481 (1989PMABDJ1364-281210.1080/13642818908205921, García de Abajo and Aizpurua Phys. Rev. B 56, 15873 (1997PRBMDO0163-182910.1103/PhysRevB.56.15873, García de Abajo and Kociak Phys. Rev. Lett. 100, 106804 (2008PRLTAO0031-900710.1103/PhysRevLett.100.106804, Boudarham and Kociak Phys. Rev. B 85, 245447 (2012PRBMDO1098-012110.1103/PhysRevB.85.245447]; it makes it straightforward to predict or interpret phenomena already known for localized surface plasmons such as environment-related energy shifts or the possibility of 3D mapping of the related surface charge densities [Collins et al. ACS Photonics 2, 1628 (2015APCHD52330-402210.1021/acsphotonics.5b00421].

  5. Sensitivity analysis of the stiffness between the frame structure and the frequency and vibration mode

    Science.gov (United States)

    Chen, Wenyuan

    2018-03-01

    The modal parameters such as natural frequency and vibration mode of the frame structure of the layer stiffness sensitivity is inconsistent. This article focuses on the theoretical derivation of the frequency and mode of the frame structure layer stiffness of the first-order sensitivity. The numerical examples show that the frame structure of layer stiffness higher than with the first order sensitivity vibration frequency.

  6. A nonlinear multi-mode wideband piezoelectric vibration-based energy harvester using compliant orthoplanar spring

    Energy Technology Data Exchange (ETDEWEB)

    Dhote, Sharvari, E-mail: sharvari.dhote@mail.utoronto.ca; Zu, Jean; Zhu, Yang [Department of Mechanical and Industrial Engineering, University of Toronto, 5 King' s College Road, Toronto, Ontario M5S-3G8 (Canada)

    2015-04-20

    In this paper, a nonlinear wideband multi-mode piezoelectric vibration-based energy harvester (PVEH) is proposed based on a compliant orthoplanar spring (COPS), which has an advantage of providing multiple vibration modes at relatively low frequencies. The PVEH is made of a tri-leg COPS flexible structure, where three fixed-guided beams are capable of generating strong nonlinear oscillations under certain base excitation. A prototype harvester was fabricated and investigated through both finite-element analysis and experiments. The frequency response shows multiple resonance which corresponds to a hardening type of nonlinear resonance. By adding masses at different locations on the COPS structure, the first three vibration modes are brought close to each other, where the three hardening nonlinear resonances provide a wide bandwidth for the PVEH. The proposed PVEH has enhanced performance of the energy harvester in terms of a wide frequency bandwidth and a high-voltage output under base excitations.

  7. Vibrational relaxation induced population inversions in laser pumped polyatomic molecules

    International Nuclear Information System (INIS)

    Shamah, I.; Flynn, G.; Columbia Univ., New York

    1981-01-01

    Conditions for population inversion in laser pumped polyatomic molecules are described. For systems which exhibit metastable vibrational population distributions, large, long lived inversions are possible even when the vibrational modes are strongly coupled by rapid collisional vibration-vibration (V-V) energy transfer. Overtone states of a hot mode are found to invert with respect to fundamental levels of a cold mode even at V-V steady state. Inversion persists for a V-T/R relaxation time. A gain of 4 m -1 for the 2ν 3 → ν 2 transition in CH 3 F (lambda approx. 15.9 μ) was found assuming a spontaneous emission lifetime of 10 s for this transition. General equations are derived which can be used to determine the magnitude of population inversion in any laser pumped, vibrationally metastable, polyatomic molecule. A discussion of factors controlling the population maxima of different vibrational states in optically pumped, V-V equilibrated metastable polyatomics is also given. (orig./WL)

  8. Four-port mode-selective silicon optical router for on-chip optical interconnect.

    Science.gov (United States)

    Jia, Hao; Zhou, Ting; Fu, Xin; Ding, Jianfeng; Zhang, Lei; Yang, Lin

    2018-04-16

    We propose and demonstrate a four-port mode-selective optical router on a silicon-on-insulator platform. The passive routing property ensures that the router consumes no power to establish the optical links. For each port, input signals with different modes are selectively routed to the target ports through the pre-designed architecture. In general, the device intrinsically supports broadcasting of multiplexed signals from one port to the other three ports through mode division multiplexing. In some applications, the input signal from one port would only be sent to another port as in reconfigurable optical routers. The prototype is constructed by mode multiplexers/de-multiplexers and single-mode interconnect waveguides between them. The insertion losses for all optical links are lower than 8.0 dB, and the largest optical crosstalk values are lower than -18.7 dB and -22.0 dB for the broadcasting and port-to-port routing modes, respectively, at the wavelength range of 1525-1565 nm. In order to verify the routing functionality, a 40-Gbps bidirectional data transmission experiment is performed. The device offers a promising building block for passive routing by utilizing the dimension of the modes.

  9. Anomalous vibrational modes in acetanilide: A F.D.S. incoherent inelastic neutron scattering study

    International Nuclear Information System (INIS)

    Barthes, M.; Moret, J.; Eckert, J.; Johnson, S.W.; Swanson, B.I.; Unkefer, C.J.

    1991-01-01

    The origin of the anomalous infra-red and Raman modes in acetanilide (C 6 H 5 NHCOCH 3 , or ACN), remains a subject of considerable controversy. One family of theoretical models involves Davydov-like solitons nonlinear vibrational coupling, or ''polaronic'' localized modes. An alternative interpretation of the extra-bands in terms of a Fermi resonance was proposed and recently the existence of slightly non-degenerate hydrogen atom configurations in the H-bond was suggested as an explanation for the anomalies. In this paper we report some new results on the anomalous vibrational modes in ACN that were obtained by inelastic incoherent neutron scattering (INS)

  10. The application of infrared synchrotron radiation to the study of interfacial vibrational modes

    International Nuclear Information System (INIS)

    Hirschmugl, C.J.; Williams, G.P.

    1992-01-01

    Synchrotron radiation provides an extremely bright broad-band source in the infrared which is ideally suited to the study of surface and interface vibrational modes in the range 50--3,000 cm -1 . Thus it covers the important range of molecule-substrate interactions, as well as overlapping with the more easily accessible near-ir region where molecular internal modes are found. Compared to standard broadband infrared sources such as globars, not only is it 1,000 times brighter, but its emittance matches the phase-space of the electrochemical cell leading to full utilization of this brightness advantage. In addition, the source is more stable even than water-cooled globars in vacuum for both short-term and long-term fluctuations. The authors summarize the properties of synchrotron radiation in the infrared, in particular pointing out the distinct differences between this and the x-ray region. They use experimental data in discussing important issues of signal to noise and address the unique problems and advantages of the synchrotron source. Thus they emphasize the important considerations necessary for developing new facilities. This analysis then leads to a discussion of phase-space matching to electrochemical cells, and to other surfaces in vacuum. Finally they show several examples of the application of infrared synchrotron radiation to surface vibrational spectroscopy. The examples are for metal crystal surfaces in ultra-high vacuum and include CO/Cu(100) and (111) and CO/K/Cu(100). The experiments show how the stability of the synchrotron source allows subtle changes in the background to be observed in addition to the discrete vibrational modes. These changes are due to electronic states induced by the adsorbate. In some cases the authors have seen interferences between these and the discrete vibrational modes, leading to a breakdown of the dipole selection rules, and the observation of additional modes

  11. Optomechanical proposal for monitoring microtubule mechanical vibrations

    Czech Academy of Sciences Publication Activity Database

    Barzanjeh, Sh.; Salari, V.; Tuszynski, J. A.; Cifra, Michal; Simon, C.

    2017-01-01

    Roč. 96, č. 1 (2017), č. článku 012404. ISSN 2470-0045 R&D Projects: GA ČR(CZ) GA15-17102S Grant - others:AV ČR(CZ) SAV-15-22 Program:Bilaterální spolupráce Institutional support: RVO:67985882 Keywords : Vibrational modes * Microtubule * Resonance frequencies Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 2.366, year: 2016

  12. Identification of surface species by vibrational normal mode analysis. A DFT study

    Science.gov (United States)

    Zhao, Zhi-Jian; Genest, Alexander; Rösch, Notker

    2017-10-01

    Infrared spectroscopy is an important experimental tool for identifying molecular species adsorbed on a metal surface that can be used in situ. Often vibrational modes in such IR spectra of surface species are assigned and identified by comparison with vibrational spectra of related (molecular) compounds of known structure, e. g., an organometallic cluster analogue. To check the validity of this strategy, we carried out a computational study where we compared the normal modes of three C2Hx species (x = 3, 4) in two types of systems, as adsorbates on the Pt(111) surface and as ligands in an organometallic cluster compound. The results of our DFT calculations reproduce the experimental observed frequencies with deviations of at most 50 cm-1. However, the frequencies of the C2Hx species in both types of systems have to be interpreted with due caution if the coordination mode is unknown. The comparative identification strategy works satisfactorily when the coordination mode of the molecular species (ethylidyne) is similar on the surface and in the metal cluster. However, large shifts are encountered when the molecular species (vinyl) exhibits different coordination modes on both types of substrates.

  13. Azimuthal decomposition of optical modes

    CSIR Research Space (South Africa)

    Dudley, Angela L

    2012-07-01

    Full Text Available This presentation analyses the azimuthal decomposition of optical modes. Decomposition of azimuthal modes need two steps, namely generation and decomposition. An azimuthally-varying phase (bounded by a ring-slit) placed in the spatial frequency...

  14. Cladding modes of optical fibers: properties and applications

    International Nuclear Information System (INIS)

    Ivanov, Oleg V; Nikitov, Sergei A; Gulyaev, Yurii V

    2006-01-01

    One of the new methods of fiber optics uses cladding modes for controlling propagation of radiation in optical fibers. This paper reviews the results of studies on the propagation, excitation, and interaction of cladding modes in optical fibers. The resonance between core and cladding modes excited by means of fiber Bragg gratings, including tilted ones, is analyzed. Propagation of cladding modes in microstructured fibers is considered. The most frequently used method of exciting cladding modes is described, based on the application of long-period fiber gratings. Examples are presented of long-period gratings used as sensors and gain equalizers for fiber amplifiers, as well as devices for coupling light into and out of optical fibers. (instruments and methods of investigation)

  15. Single-mode optical fibres

    CERN Document Server

    Cancellieri, G

    1991-01-01

    This book describes signal propagation in single-mode optical fibres for telecommunication applications. Such description is based on the analysis of field propagation, considering waveguide properties and also some of the particular characteristics of the material fibre. The book covers such recent advances as, coherent transmissions; optical amplification; MIR fibres; polarization maintaining; polarization diversity and photon counting.

  16. Vibration-rotational overtones absorption of solid hydrogens using optoacoustic spectroscopy technique

    International Nuclear Information System (INIS)

    Vieira, M.M.F.

    1985-01-01

    Vibrational-rotational overtones absorption solid hydrogens (H 2 , D 2 , HD) is studied using pulsed laser piezoeletric transducer (PULPIT) optoacoustic spectroscopy is studied. A general downward shift in energy from isolated molecular energies is observed. Studying normal-hydrogen it was observed that the phonon excitations associated with double-molecular transitions are predominantly transverse-optical phonons, whereas the excitations associated with single-molecular transitions are predominantly longitudinal - optical phonons. Multiplet structures were observed for certain double transitions in parahydrogen and orthodeuterium. The HD spectrum, besides presenting the sharp zero-phonon lines and the associated phonon side bands, like H 2 and D 2 , showed also two different features. This observation was common to all the transitions involving pure rotational excitation in H 2 and D 2 , which showed broad linewidths. This, together with some other facts (fluorescence lifetime *approx*10 5 sec; weak internal vibration and lattice coupling), led to the proposition of a mechanism for the fast nonradiative relaxation in solid hydrogens, implied from some observed experimental evidences. This relaxation, due to strong coupling, would happen in two steps: the internal vibration modes would relax to the rotational modes of the molecules, and then this rotational modes would relax to the lattice vibration modes. (Author) [pt

  17. Recent Advances In Structural Vibration And Failure Mode Control In Mainland China: Theory, Experiments And Applications

    International Nuclear Information System (INIS)

    Li Hui; Ou Jinping

    2008-01-01

    A number of researchers have been focused on structural vibration control in the past three decades over the world and fruit achievements have been made. This paper introduces the recent advances in structural vibration control including passive, active and semiactive control in mainland China. Additionally, the co-author extends the structural vibration control to failure mode control. The research on the failure mode control is also involved in this paper. For passive control, this paper introduces full scale tests of buckling-restrained braces conducted to investigate the performance of the dampers and the second-editor of the Code of Seismic Design for Buildings. For active control, this paper introduces the HMD system for wind-induced vibration control of the Guangzhou TV tower. For semiactive control, the smart damping devices, algorithms for semi-active control, design methods and applications of semi-active control for structures are introduced in this paper. The failure mode control for bridges is also introduced

  18. Research and design of quasi-optical mode converter

    International Nuclear Information System (INIS)

    Liu Jianwei; Zhao Qing

    2013-01-01

    This paper presents a quasi-optical mode converter which can convert the output mode of gyrotrons and other high-power microwave oscillators into quasi-Gaussian beam, aiming to achieve transverse output of quasi-Gaussian beam TEM 00 mode. First, we analyze mode propagation in the waveguide and the working mechanism of the Vlasov launcher. Then the radiation fields are calculated using vector diffraction theory. At last a quasi-optical mode converter is designed to convert the 94 GHz, TE 62 mode millimeter wave into quasi-Gaussian beam with programming method. The results prove that quasi-Gaussian mode can be obtained at the output window with a simple Vlasov launcher and two mirrors, and the power transmission efficiency of the quasi-optical mode converter reaches to 87.5%. (authors)

  19. Nonlinear Vibration and Mode Shapes of FG Cylindrical Shells

    Directory of Open Access Journals (Sweden)

    Saeed Mahmoudkhani

    Full Text Available Abstract The nonlinear vibration and normal mode shapes of FG cylindrical shells are investigated using an efficient analytical method. The equations of motion of the shell are based on the Donnell’s non-linear shallow-shell, and the material is assumed to be gradually changed across the thickness according to the simple power law. The solution is provided by first discretizing the equations of motion using the multi-mode Galerkin’s method. The nonlinear normal mode of the system is then extracted using the invariant manifold approach and employed to decouple the discretized equations. The homotopy analysis method is finally used to determine the nonlinear frequency. Numerical results are presented for the backbone curves of FG cylindrical shells, nonlinear mode shapes and also the nonlinear invariant modal surfaces. The volume fraction index and the geometric properties of the shell are found to be effective on the type of nonlinear behavior and also the nonlinear mode shapes of the shell. The circumferential half-wave numbers of the nonlinear mode shapes are found to change with time especially in a thinner cylinder.

  20. Computation of expectation values from vibrational coupled-cluster at the two-mode coupling level

    DEFF Research Database (Denmark)

    Zoccante, Alberto; Seidler, Peter; Christiansen, Ove

    2011-01-01

    In this work we show how the vibrational coupled-cluster method at the two-mode coupling level can be used to calculate zero-point vibrational averages of properties. A technique is presented, where any expectation value can be calculated using a single set of Lagrangian multipliers computed...

  1. Blind identification of full-field vibration modes of output-only structures from uniformly-sampled, possibly temporally-aliased (sub-Nyquist), video measurements

    Science.gov (United States)

    Yang, Yongchao; Dorn, Charles; Mancini, Tyler; Talken, Zachary; Nagarajaiah, Satish; Kenyon, Garrett; Farrar, Charles; Mascareñas, David

    2017-03-01

    Enhancing the spatial and temporal resolution of vibration measurements and modal analysis could significantly benefit dynamic modelling, analysis, and health monitoring of structures. For example, spatially high-density mode shapes are critical for accurate vibration-based damage localization. In experimental or operational modal analysis, higher (frequency) modes, which may be outside the frequency range of the measurement, contain local structural features that can improve damage localization as well as the construction and updating of the modal-based dynamic model of the structure. In general, the resolution of vibration measurements can be increased by enhanced hardware. Traditional vibration measurement sensors such as accelerometers have high-frequency sampling capacity; however, they are discrete point-wise sensors only providing sparse, low spatial sensing resolution measurements, while dense deployment to achieve high spatial resolution is expensive and results in the mass-loading effect and modification of structure's surface. Non-contact measurement methods such as scanning laser vibrometers provide high spatial and temporal resolution sensing capacity; however, they make measurements sequentially that requires considerable acquisition time. As an alternative non-contact method, digital video cameras are relatively low-cost, agile, and provide high spatial resolution, simultaneous, measurements. Combined with vision based algorithms (e.g., image correlation or template matching, optical flow, etc.), video camera based measurements have been successfully used for experimental and operational vibration measurement and subsequent modal analysis. However, the sampling frequency of most affordable digital cameras is limited to 30-60 Hz, while high-speed cameras for higher frequency vibration measurements are extremely costly. This work develops a computational algorithm capable of performing vibration measurement at a uniform sampling frequency lower than

  2. Simulation of vibration modes of the fuel rod damaged due to the grid-to-rod fretting wear

    International Nuclear Information System (INIS)

    Kim, Kyu Tae; Kim, Kyeong Koo; Jang, Young Ki; Lee, Kyou Seok

    1997-01-01

    The flow-induced fuel fretting wear observed in some PWRs mainly proceeds in the grid-to-rod contact positions. The grid-to-rod fretting wear in the PWR fuel assembly depends on grid-to-rod gap size, its axial profile and flow-induced vibration. This paper describes the GRIDFORCE program which generates the axially dependent grid-to-rod gap size as a function of burnup. The axially dependent grid-to-rod gap profiles are employed to predict the fuel rod vibration mode shapes by the ANSYS code. With the help of the Paidousis empirical formula, this paper also calculates the fuel rod vibration amplitudes under various supporting conditions, which indicates that the increase of the number of unsupported mid-grids will increase the fuel rod vibration amplitude. On the other hand, the comparison of the predicted vibration mode shapes and the observed mid-grid fretting wear pattern indicates that the 1st and 6th vibration mode shapes under the supporting inactive condition at the mid-grids can simulate the observed mid-grid fretting wear profile. This paper also proposes design guidelines against the grid-to-rod fretting wear. (author). 3 refs., 8 figs

  3. Harnessing the mode mixing in optical fiber-tip cavities

    International Nuclear Information System (INIS)

    Podoliak, Nina; Horak, Peter; Takahashi, Hiroki; Keller, Matthias

    2017-01-01

    We present a systematic numerical study of Fabry–Pérot optical cavities with Gaussian-shape mirrors formed between tips of optical fibers. Such cavities can be fabricated by laser machining of fiber tips and are promising systems for achieving strong coupling between atomic particles and an optical field as required for quantum information applications. Using a mode mixing matrix method, we analyze the cavity optical eigenmodes and corresponding losses depending on a range of cavity-shape parameters, such as mirror radius of curvature, indentation depth and cavity length. The Gaussian shape of the mirrors causes mixing of optical modes in the cavity. We investigate the effect of the mode mixing on the coherent atom-cavity coupling as well as the mode matching between the cavity and a single-mode optical fiber. While the mode mixing is associated with increased cavity losses, it can also lead to an enhancement of the local optical field. We demonstrate that around the resonance between the fundamental and 2nd order Laguerre–Gaussian modes of the cavity it is possible to obtain 50% enhancement of the atom-cavity coupling at the cavity center while still maintaining low cavity losses and high cavity-fiber optical coupling. (paper)

  4. Acousto-optic resonant coupling of three spatial modes in an optical fiber.

    Science.gov (United States)

    Park, Hee Su; Song, Kwang Yong

    2014-01-27

    A fiber-optic analogue to an externally driven three-level quantum state is demonstrated by acousto-optic coupling of the spatial modes in a few-mode fiber. Under the condition analogous to electromagnetically induced transparency, a narrow-bandwidth transmission within an absorption band for the fundamental mode is demonstrated. The presented structure is an efficient converter between the fundamental mode and the higher-order modes that cannot be easily addressed by previous techniques, therefore can play a significant role in the next-generation space-division multiplexing communications as an arbitrarily mode-selectable router.

  5. Vibrational Raman optical activity of ketose monosaccharides

    Science.gov (United States)

    Bell, Alasdair F.; Hecht, Lutz; Barron, Laurence D.

    1995-07-01

    The vibrational Raman optical activity (ROA) spectra of the four ketose sugars D-fructose, L-sorbose, D-tagatose and D-psicose in aqueous solution, which have been measured in backscattering in the range ≈250-1500 cm -1, are reported. These results are combined with those from a previous ROA study of aldose and pentose sugars in an attempt to establish new vibrational assignments and to verify old ones. The high information content of these spectra provides a new perspective on all the central features of monosaccharide stereochemistry including dominant anomeric configuration, ring conformation, exocyclic CH 2OH group conformation and relative disposition of the hydroxyl groups around the ring.

  6. Optical design and suspension system of the KAGRA output mode-cleaner

    Science.gov (United States)

    Kasuya, Junko; Winterflood, John; Li, Ju; Somiya, Kentaro

    2018-02-01

    KAGRA is a Japanese large scale, underground, cryogenic gravitational telescope which is under construction in the Kamioka mine. For using cryogenic test masses, the sensitivity of KAGRA is limited mainly by quantum noise. In order to reduce quantum noise, KAGRA employs an output mode-cleaner (OMC) at the output port that filters out junk light but allows the gravitational wave signal to go through. The requirement of the KAGRA OMC is even more challenging than other telescopes in the world since KAGRA plans to tune the signal readout phase so that the signal-to-noise ratio for our primary target source can be maximized. A proper selection of optical parameters and anti-vibration devices is required for the robust operation of the OMC. In this proceeding, we show our final results of modal-model simulations, in which we downselected the cavity length, the round-trip Gouy phase shift, the finesse, and the seismic isolation ratio for the suspended optics.

  7. Normal modes of vibration in nickel

    Energy Technology Data Exchange (ETDEWEB)

    Birgeneau, R J [Yale Univ., New Haven, Connecticut (United States); Cordes, J [Cambridge Univ., Cambridge (United Kingdom); Dolling, G; Woods, A D B

    1964-07-01

    The frequency-wave-vector dispersion relation, {nu}(q), for the normal vibrations of a nickel single crystal at 296{sup o}K has been measured for the [{zeta}00], [{zeta}00], [{zeta}{zeta}{zeta}], and [0{zeta}1] symmetric directions using inelastic neutron scattering. The results can be described in terms of the Born-von Karman theory of lattice dynamics with interactions out to fourth-nearest neighbors. The shapes of the dispersion curves are very similar to those of copper, the normal mode frequencies in nickel being about 1.24 times the corresponding frequencies in copper. The fourth-neighbor model was used to calculate the frequency distribution function g({nu}) and related thermodynamic properties. (author)

  8. Recovering Intrinsic Fragmental Vibrations Using the Generalized Subsystem Vibrational Analysis.

    Science.gov (United States)

    Tao, Yunwen; Tian, Chuan; Verma, Niraj; Zou, Wenli; Wang, Chao; Cremer, Dieter; Kraka, Elfi

    2018-05-08

    Normal vibrational modes are generally delocalized over the molecular system, which makes it difficult to assign certain vibrations to specific fragments or functional groups. We introduce a new approach, the Generalized Subsystem Vibrational Analysis (GSVA), to extract the intrinsic fragmental vibrations of any fragment/subsystem from the whole system via the evaluation of the corresponding effective Hessian matrix. The retention of the curvature information with regard to the potential energy surface for the effective Hessian matrix endows our approach with a concrete physical basis and enables the normal vibrational modes of different molecular systems to be legitimately comparable. Furthermore, the intrinsic fragmental vibrations act as a new link between the Konkoli-Cremer local vibrational modes and the normal vibrational modes.

  9. Laser Covariance Vibrometry for Unsymmetrical Mode Detection

    National Research Council Canada - National Science Library

    Kobold, Michael C

    2006-01-01

    Simulated cross - spectral covariance (CSC) from optical return from simulated surface vibration indicates CW phase modulation may be an appropriate phenomenology for adequate classification of vehicles by structural mode...

  10. Mode shape combination in a two-dimensional vibration energy harvester through mass loading structural modification

    Energy Technology Data Exchange (ETDEWEB)

    Sharpes, Nathan; Kumar, Prashant [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Abdelkefi, Abdessattar; Abdelmoula, Hichem [Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Adler, Jan [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Institute of Dynamics and Vibration Research (IDS), Leibniz Universität, Hannover 30167 (Germany); Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2016-07-18

    Mode shapes in the design of mechanical energy harvesters, as a means of performance increase, have been largely overlooked. Currently, the vast majority of energy harvester designs employ some variation of a single-degree-of-freedom cantilever, and the mode shapes of such beams are well known. This is especially true for the first bending mode, which is almost exclusively the chosen vibration mode for energy harvesting. Two-dimensional beam shapes (those which curve, meander, spiral, etc., in a plane) have recently gained research interest, as they offer freedom to modify the vibration characteristics of the harvester beam for achieving higher power density. In this study, the second bending mode shape of the “Elephant” two-dimensional beam shape is examined, and its interaction with the first bending mode is evaluated. A combinatory mode shape created by using mass loading structural modification to lower the second bending modal frequency was found to interact with the first bending mode. This is possible since the first two bending modes do not share common areas of displacement. The combined mode shape is shown to produce the most power of any of the considered mode shapes.

  11. Studies on structural, optical, thermal and vibrational properties of thienyl chalcone derivative: 1-(4-Nitrophenyl)-3-(2-thienyl)prop-2-en-1-one

    Science.gov (United States)

    de Toledo, T. A.; da Costa, R. C.; Bento, R. R. F.; Al-Maqtari, H. M.; Jamalis, J.; Pizani, P. S.

    2018-03-01

    The structural, optical, thermal and vibrational properties of thienyl chalcone derivative 1-(4-Nitrophenyl)-3-(2-thienyl)prop-2-en-1-one, C13H9NO3S were investigated combining nuclear magnetic resonance (1H and 13C NMR), X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-vis spectroscopy at room temperature assisted by density functional theory (DFT) calculations and Raman scattering at the temperature range 303-463 K. The electronic properties, including excitation energies, oscillator strengths, HOMO and LUMO energies were calculated by time-dependent DFT (TD-DFT) to complement the experimental findings. The B3LYP/6-311G (d,p) (B3LYP/cc-pVTZ) calculations led to the identification of 'two minima on the molecules' potential energy surfaces. From these calculations, it was predicted that the most stable conformer for C13H9NO3S in the gas phase is founded at 0 K relationship to dihedral angle C8sbnd C9sbnd C10sbnd S1, in agreement with XRD results. The molecular plot showed that the electrical charge mobility in the molecule occurs from thiophene to benzene ring. The optical band gap energy calculated from the difference between HOMO and LUMO orbitals was founded to be ∼3.87 (3.82) eV, in close agreement with the experimental value of 2.94 eV. The comparison between experimental and theoretical vibrational spectra gives a precise knowledge of the fundamental vibrational modes and leads to a better interpretation of the experimental Raman and infrared spectra. As temperature increases from room temperature to 443 K, it was observed the current phonon anharmonicity effects associated to changes in the Raman line intensities, line-widths and red-shift, in special in the external modes region, whereas the internal modes region remains almost unchanged due its strong chemical bonds. Furthermore, C13H9NO3S goes to phase transition in the temperature range 453-463 K. This thermal phenomenon was attributed to the disappearance of the lattice (∼10-200 cm-1

  12. Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas

    International Nuclear Information System (INIS)

    Perelomova, A.

    2010-01-01

    Two dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place, are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into thermal mode and internal vibrational degrees of freedom of a relaxing gas. The final dynamic equations are instantaneous; they include a quadratic nonlinear acoustic source, reflecting the nonlinear character of interaction of low-frequency acoustic and non-acoustic motions of the fluid. All types of sound, periodic or aperiodic, may serve as an acoustic source of both phenomena. The low-frequency sound is considered in this study. Some conclusions about temporal behavior of non-acoustic modes caused by periodic and aperiodic sound are made. Under certain conditions, acoustic cooling takes place instead of heating. (author)

  13. Local vibrational modes of the formic acid dimer - the strength of the double hydrogen bond

    Science.gov (United States)

    Kalescky, R.; Kraka, E.; Cremer, D.

    2013-07-01

    The 24 normal and 24 local vibrational modes of the formic acid dimer formed by two trans formic acid monomers to a ring (TT1) are analysed utilising preferentially experimental frequencies, but also CCSD(T)/CBS and ωB97X-D harmonic vibrational frequencies. The local hydrogen bond (HB) stretching frequencies are at 676 cm-1 and by this 482 and 412 cm-1 higher compared to the measured symmetric and asymmetric HB stretching frequencies at 264 and 194 cm-1. The adiabatic connection scheme between local and normal vibrational modes reveals that the lowering is due to the topology of dimer TT1, mass coupling, and avoided crossings involving the HṡṡṡOC bending modes. The HB local mode stretching force constant is related to the strength of the HB whereas the normal mode stretching force constant and frequency lead to an erroneous underestimation of the HB strength. The HB in TT1 is stabilised by electron delocalisation in the O=C-O units fostered by forming a ring via double HBs. This implies that the CO apart from the OH local stretching frequencies reflect the strength of the HB via their red or blue shifts relative to their corresponding values in trans formic acid.

  14. Optical Measurement of Cable and String Vibration

    Directory of Open Access Journals (Sweden)

    Y. Achkire

    1998-01-01

    Full Text Available This paper describes a non contacting measurement technique for the transverse vibration of small cables and strings using an analog position sensing detector. On the one hand, the sensor is used to monitor the cable vibrations of a small scale mock-up of a cable structure in order to validate the nonlinear cable dynamics model. On the other hand, the optical sensor is used to evaluate the performance of an active tendon control algorithm with guaranteed stability properties. It is demonstrated experimentally, that a force feedback control law based on a collocated force sensor measuring the tension in the cable is feasible and provides active damping in the cable.

  15. CO 2 laser photoacoustic spectra and vibrational modes of heroin ...

    Indian Academy of Sciences (India)

    Heroin, morphine and narcotine are very large molecules having 50, 40 and 53 atoms respectively. Moderately high resolution photoacoustic (PA) spectra have been recorded in 9.6 m and 10.6 m regions of CO2 laser. It is very difficult to assign the modes of vibrations for PA bands by comparison with conventional low ...

  16. Pressure-dependent optical and vibrational properties of monolayer molybdenum disulfide

    KAUST Repository

    Nayak, Avinash P.

    2015-01-14

    Controlling the band gap by tuning the lattice structure through pressure engineering is a relatively new route for tailoring the optoelectronic properties of two-dimensional (2D) materials. Here, we investigate the electronic structure and lattice vibrational dynamics of the distorted monolayer 1T-MoS2 (1T′) and the monolayer 2H-MoS2 via a diamond anvil cell (DAC) and density functional theory (DFT) calculations. The direct optical band gap of the monolayer 2H-MoS2 increases by 11.7% from 1.85 to 2.08 eV, which is the highest reported for a 2D transition metal dichalcogenide (TMD) material. DFT calculations reveal a subsequent decrease in the band gap with eventual metallization of the monolayer 2H-MoS2, an overall complex structure-property relation due to the rich band structure of MoS2. Remarkably, the metastable 1T′-MoS2 metallic state remains invariant with pressure, with the J2, A1g, and E2g modes becoming dominant at high pressures. This substantial reversible tunability of the electronic and vibrational properties of the MoS2 family can be extended to other 2D TMDs. These results present an important advance toward controlling the band structure and optoelectronic properties of monolayer MoS2 via pressure, which has vital implications for enhanced device applications.

  17. A simple optical method for measuring the vibration amplitude of a speaker

    OpenAIRE

    UEDA, Masahiro; YAMAGUCHI, Toshihiko; KAKIUCHI, Hiroki; SUGA, Hiroshi

    1999-01-01

    A simple optical method has been proposed for measuring the vibration amplitude of a speaker vibrating with a frequency of approximately 10 kHz. The method is based on a multiple reflection between a vibrating speaker plane and a mirror parallel to that speaker plane. The multiple reflection can magnify a dispersion of the laser beam caused by the vibration, and easily make a measurement of the amplitude. The measuring sensitivity ranges between sub-microns and 1 mm. A preliminary experim...

  18. Mode pattern of internal flow in a water droplet on a vibrating hydrophobic surface.

    Science.gov (United States)

    Kim, Hun; Lim, Hee-Chang

    2015-06-04

    The objective of this study is to understand the mode pattern of the internal flow in a water droplet placed on a hydrophobic surface that periodically and vertically vibrates. As a result, a water droplet on a vibrating hydrophobic surface has a typical shape that depends on each resonance mode, and, additionally, we observed a diversified lobe size and internal flows in the water droplet. The size of each lobe at the resonance frequency was relatively greater than that at the neighboring frequencies, and the internal flow of the nth order mode was also observed in the flow visualization. In general, large symmetrical flow streams were generated along the vertical axis in each mode, with a large circulating movement from the bottom to the top, and then to the triple contact line along the droplet surface. In contrast, modes 2 and 4 generated a Y-shaped flow pattern, in which the flow moved to the node point in the lower part of the droplet, but modes 6 and 8 had similar patterns, with only a little difference. In addition, as a result of the PIV measurement, while the flow velocity of mode 4 was faster than that of model 2, those of modes 6 and 8 were almost similar.

  19. Frustration of Bragg reflection by cooperative dual-mode interference: a new mode of optical propagation.

    Science.gov (United States)

    Yariv, A

    1998-12-01

    A new optical mode of propagation is described, which is the natural eigenmode (supermode) of a fiber (or any optical waveguide) with two cospatial periodic gratings. The mode frustrates the backward Bragg scattering from the grating by destructive interference of its two constituent submodes (which are eigenmodes of a uniform waveguide). It can be used in a new type of spatial mode conversion in optical guides.

  20. Ultrasensitive Broadband Probing of Molecular Vibrational Modes with Multifrequency Optical Antennas

    Czech Academy of Sciences Publication Activity Database

    Aouani, H.; Šípová, Hana; Rahmani, M.; Navarro-Cia, M.; Hegnerová, Kateřina; Homola, Jiří; Hong, M.; Maier, S. A.

    2013-01-01

    Roč. 7, č. 1 (2013), s. 669-675 ISSN 1936-0851 R&D Projects: GA MŠk(CZ) LH11102 Institutional support: RVO:67985882 Keywords : plasmonic * nanoantenna * vibrational spectroscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 12.033, year: 2013

  1. Effect of instantaneous and continuous quenches on the density of vibrational modes in model glasses

    Science.gov (United States)

    Lerner, Edan; Bouchbinder, Eran

    2017-08-01

    Computational studies of supercooled liquids often focus on various analyses of their "underlying inherent states"—the glassy configurations at zero temperature obtained by an infinitely fast (instantaneous) quench from equilibrium supercooled states. Similar protocols are also regularly employed in investigations of the unjamming transition at which the rigidity of decompressed soft-sphere packings is lost. Here we investigate the statistics and localization properties of low-frequency vibrational modes of glassy configurations obtained by such instantaneous quenches. We show that the density of vibrational modes grows as ωβ with β depending on the parent temperature T0 from which the glassy configurations were instantaneously quenched. For quenches from high temperature liquid states we find β ≈3 , whereas β appears to approach the previously observed value β =4 as T0 approaches the glass transition temperature. We discuss the consistency of our findings with the theoretical framework of the soft potential model, and contrast them with similar measurements performed on configurations obtained by continuous quenches at finite cooling rates. Our results suggest that any physical quench at rates sufficiently slower than the inverse vibrational time scale—including all physically realistic quenching rates of molecular or atomistic glasses—would result in a glass whose density of vibrational modes is universally characterized by β =4 .

  2. Optical measuring system with an interrogator and a polymer-based single-mode fibre optic sensor system

    DEFF Research Database (Denmark)

    2017-01-01

    The present invention relates to an optical measuring system comprising a polymer-based single-mode fibre-optic sensor system (102), an optical interrogator (101), and an optical arrangement (103) interconnecting the optical interrogator (101) and the polymer-based single-mode fibre-optic sensor...... system (102). The invention further relates to an optical interrogator adapted to be connected to a polymer-based single-mode fibre-optic sensor system via an optical arrangement. The interrogator comprises a broadband light source arrangement (104) and a spectrum analysing arrangement which receives...

  3. Estimation of the mechanical properties of the eye through the study of its vibrational modes.

    Directory of Open Access Journals (Sweden)

    M Á Aloy

    Full Text Available Measuring the eye's mechanical properties in vivo and with minimally invasive techniques can be the key for individualized solutions to a number of eye pathologies. The development of such techniques largely relies on a computational modelling of the eyeball and, it optimally requires the synergic interplay between experimentation and numerical simulation. In Astrophysics and Geophysics the remote measurement of structural properties of the systems of their realm is performed on the basis of (helio-seismic techniques. As a biomechanical system, the eyeball possesses normal vibrational modes encompassing rich information about its structure and mechanical properties. However, the integral analysis of the eyeball vibrational modes has not been performed yet. Here we develop a new finite difference method to compute both the spheroidal and, specially, the toroidal eigenfrequencies of the human eye. Using this numerical model, we show that the vibrational eigenfrequencies of the human eye fall in the interval 100 Hz-10 MHz. We find that compressible vibrational modes may release a trace on high frequency changes of the intraocular pressure, while incompressible normal modes could be registered analyzing the scattering pattern that the motions of the vitreous humour leave on the retina. Existing contact lenses with embebed devices operating at high sampling frequency could be used to register the microfluctuations of the eyeball shape we obtain. We advance that an inverse problem to obtain the mechanical properties of a given eye (e.g., Young's modulus, Poisson ratio measuring its normal frequencies is doable. These measurements can be done using non-invasive techniques, opening very interesting perspectives to estimate the mechanical properties of eyes in vivo. Future research might relate various ocular pathologies with anomalies in measured vibrational frequencies of the eye.

  4. Natural Frequencies and Vibrating Modes for a Magnetic Planetary Gear Drive

    Directory of Open Access Journals (Sweden)

    Lizhong Xu

    2012-01-01

    Full Text Available In this paper, a dynamic model for a magnetic planetary gear drive is proposed. Based on the model, the dynamic equations for the magnetic planetary gear drive are given. From the magnetic meshing forces and torques between the elements for the drive system, the tangent and radial magnetic meshing stiffness is obtained. Using these equations, the natural frequencies and the modes of the magnetic planetary gear drive are investigated. The sensitivity of the natural frequencies to the system parameters is discussed. Results show that the pole pair number and the air gap have obvious effects on the natural frequencies. For the planetary gear number larger than two, the vibrations of the drive system include the torsion mode of the center elements, the translation mode of the center elements, and the planet modes. For the planetary gear number equal to two, the planet mode does not occur, the crown mode and the sun gear mode occur.

  5. Integrated optical isolators based on two-mode interference couplers

    International Nuclear Information System (INIS)

    Sun, Yiling; Zhou, Haifeng; Jiang, Xiaoqing; Hao, Yinlei; Yang, Jianyi; Wang, Minghua

    2010-01-01

    This paper presents an optical waveguide isolator based on two-mode interference (TMI) couplers, by utilizing the magneto-optical nonreciprocal phase shift (NPS). The operating principle of this device is to utilize the difference between the nonreciprocal phase shifts of the two lowest-order modes. A two-dimensional (2D) semi-vectorial finite difference method is used to calculate the difference between the nonreciprocal phase shifts of the two lowest-order modes and optimize the parameters. The proposed device may play an important role in integrated optical devices and optical communication systems

  6. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  7. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  8. Optimize Etching Based Single Mode Fiber Optic Temperature Sensor

    OpenAIRE

    Ajay Kumar; Dr. Pramod Kumar

    2014-01-01

    This paper presents a description of etching process for fabrication single mode optical fiber sensors. The process of fabrication demonstrates an optimized etching based method to fabricate single mode fiber (SMF) optic sensors in specified constant time and temperature. We propose a single mode optical fiber based temperature sensor, where the temperature sensing region is obtained by etching its cladding diameter over small length to a critical value. It is observed that th...

  9. Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

    Science.gov (United States)

    Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.

    2016-09-01

    Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.

  10. Thermo-optical properties of optically stimulated luminescence in feldspars

    DEFF Research Database (Denmark)

    Poolton, N.R.J.; Bøtter-Jensen, L.; Johnsen, O.

    1995-01-01

    Optically stimulated luminescence processes in feldspars are subject to competing thermal enhancement and quenching processes: this article describes the thermal enhancement effects for orthoclase, albite and plagioclase feldspars. It is demonstrated that certain lattice vibrational modes can be ...

  11. Optical and vibrational properties of (ZnO){sub k} In{sub 2}O{sub 3} natural superlattice nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Margueron, Samuel [Laboratoire Matériaux Optiques, Photonique et Systèmes, Université de Lorraine et CentraleSupélec, 57070 Metz (France); John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Maryland 02138 (United States); Pokorny, Jan; Skiadopoulou, Stella; Kamba, Stanislav [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Liang, Xin [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu Province 213164 (China); Clarke, David R. [John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Maryland 02138 (United States)

    2016-05-21

    A thermodynamically stable series of superlattices, (ZnO){sub k}In{sub 2}O{sub 3}, form in the ZnO-In{sub 2}O{sub 3} binary oxide system for InO{sub 1.5} concentrations from about 13 up to about 33 mole percent (m/o). These natural superlattices, which consist of a periodic stacking of single, two-dimensional sheets of InO{sub 6} octahedra, are found to give rise to systematic changes in the optical and vibrational properties of the superlattices. Low-frequency Raman scattering provides the evidence for the activation of acoustic phonons due to the folding of Brillouin zone. New vibrational modes at 520 and 620 cm{sup −1}, not present in either ZnO or In{sub 2}O{sub 3}, become Raman active. These new modes are attributed to collective plasmon oscillations localized at the two-dimensional InO{sub 1.5} sheets. Infrared reflectivity experiments, and simulations taking into account a negative dielectric susceptibility due to electron carriers in ZnO and interface modes of the dielectric layer of InO{sub 2}, explain the occurrence of these new modes. We postulate that a localized electron gas forms at the ZnO/InO{sub 2} interface due to the electron band alignment and polarization effects. All our observations suggest that there are quantum contributions to the thermal and electrical conductivity in these natural superlattices.

  12. Mode conversion in hybrid optical fiber coupler

    Science.gov (United States)

    Stasiewicz, Karol A.; Marc, P.; Jaroszewicz, Leszek R.

    2012-04-01

    Designing of all in-line fiber optic systems with a supercontinuum light source gives some issues. The use of a standard single mode fiber (SMF) as an input do not secure single mode transmission in full wavelength range. In the paper, the experimental results of the tested hybrid fiber optic coupler were presented. It was manufactured by fusing a standard single mode fiber (SMF28) and a photonic crystal fiber (PCF). The fabrication process is based on the standard fused biconical taper technique. Two types of large mode area fibers (LMA8 and LAM10 NKT Photonics) with different air holes arrangements were used as the photonic crystal fiber. Spectral characteristics within the range of 800 nm - 1700 nm were presented. All process was optimized to obtain a mode conversion between SMF and PCF and to reach a single mode transmission in the PCF output of the coupler.

  13. All-fiber optical mode switching based on cascaded mode selective couplers for short-reach MDM networks

    Science.gov (United States)

    Ren, Fang; Li, Juhao; Wu, Zhongying; Yu, Jinyi; Mo, Qi; Wang, Jianping; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

    2017-04-01

    We propose and experimentally demonstrate an all-fiber optical mode switching structure supporting independent switching, exchanging, adding, and dropping functionalities in which each mode can be switched individually. The mode switching structure consists of cascaded mode selective couplers (MSCs) capable of exciting and selecting specific higher order modes in few-mode fibers with high efficiency and one multiport optical switch routing the independent spatial modes to their destinations. The data carried on three different spatial modes can be switched, exchanged, added, and dropped through this all-fiber structure. For this experimental demonstration, optical on-off-keying (OOK) signals at 10-Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. The mode switch exhibits power penalties of less than 3.1 dB after through operation, less than 2.7 dB after exchange operation, less than 2.8 dB after switching operation, and less than 1.6 dB after mode adding and dropping operations at the bit-error rate (BER) of 10-3, while all three channels carried on three spatial modes are simultaneously routed. The proposed structure, compatible with current optical switching networks based on single-mode fibers, can potentially be used to expand the switching scalability in advanced and flexible short-reach mode-division multiplexing-based networks.

  14. Developments In Electronic Speckle Pattern Interferometry For Automotive Vibration Analysis.

    Science.gov (United States)

    Davies, Jeremy C.; Buckberry, Clive H.; Jones, Julian D. C.; Pannell, Chris N.

    1989-01-01

    The incorporation of monomode fibre optics into an argon ion powered Electronic Speckle Pattern Interferometer (ESPI) is reported. The system, consisting of an optics assembly linked to the laser and a CCD camera transceiver, flexibly connected by 40m of monomode fibre optic cable to the optics, has been used to analyse the modal behaviour of structures up to 5m X 3m X 2m in size. Phase modulation of the reference beam in order to operate in a heterodyne mode has been implemented using a piezo-electric crystal operating on the monomode fibre. A new mode of operation - sequential time-average subtraction - and the results of a new processing algorithm are also reported. Their implementation enables speckle free, time-average vibration maps to be generated in real-time on large, unstable structures. Example results for a four cylinder power unit, a vehicle body shell component and an engine oil pan are included. In all cases the analysis was conducted in a general workshop environment without the need for vibration isolation facilities.

  15. Adaptive Robust Sliding Mode Vibration Control of a Flexible Beam Using Piezoceramic Sensor and Actuator: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Ruo Lin Wang

    2014-01-01

    Full Text Available This paper presents an experimental study of an adaptive robust sliding mode control scheme based on the Lyapunov’s direct method for active vibration control of a flexible beam using PZT (lead zirconate titanate sensor and actuator. PZT, a type of piezoceramic material, has the advantages of high reliability, high bandwidth, and solid state actuation and is adopted here in forms of surface-bond patches for vibration control. Two adaptive robust sliding mode controllers for vibration suppression are designed: one uses a discontinuous bang-bang robust compensator and the other uses a smooth compensator with a hyperbolic tangent function. Both controllers guarantee asymptotic stability, as proved by the Lyapunov’s direct method. Experimental results verified the effectiveness and the robustness of both adaptive sliding mode controllers. However, from the experimental results, the bang-bang robust compensator causes small-magnitude chattering because of the discontinuous switching actions. With the smooth compensator, vibration is quickly suppressed and no chattering is induced. Furthermore, the robustness of the controllers is successfully demonstrated with ensured effectiveness in vibration control when masses are added to the flexible beam.

  16. Direct detection of the optical field beyond single polarization mode.

    Science.gov (United States)

    Che, Di; Sun, Chuanbowen; Shieh, William

    2018-02-05

    Direct detection is traditionally regarded as a detection method that recovers only the optical intensity. Compared with coherent detection, it owns a natural advantage-the simplicity-but lacks a crucial capability of field recovery that enables not only the multi-dimensional modulation, but also the digital compensation of the fiber impairments linear with the optical field. Full-field detection is crucial to increase the capacity-distance product of optical transmission systems. A variety of methods have been investigated to directly detect the optical field of the single polarization mode, which normally sends a carrier traveling with the signal for self-coherent detection. The crux, however, is that any optical transmission medium supports at least two propagating modes (e.g. single mode fiber supports two polarization modes), and until now there is no direct detection that can recover the complete set of optical fields beyond one polarization, due to the well-known carrier fading issue after mode demultiplexing induced by the random mode coupling. To avoid the fading, direct detection receivers should recover the signal in an intensity space isomorphic to the optical field without loss of any degrees of freedom, and a bridge should be built between the field and its isomorphic space for the multi-mode field recovery. Based on this thinking, we propose, for the first time, the direct detection of dual polarization modes by a novel receiver concept, the Stokes-space field receiver (SSFR) and its extension, the generalized SSFR for multiple spatial modes. The idea is verified by a dual-polarization field recovery of a polarization-multiplexed complex signal over an 80-km single mode fiber transmission. SSFR can be applied to a much wider range of fields beyond optical communications such as coherent sensing and imaging, where simple field recovery without an extra local laser is desired for enhanced system performance.

  17. Effects of phase and coupling between the vibrational modes on selective excitation in coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Patel, Vishesha; Malinovsky, Vladimir S.; Malinovskaya, Svetlana

    2010-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy has been a major tool of investigation of biological structures as it contains the vibrational signature of molecules. A quantum control method based on chirped pulse adiabatic passage was recently proposed for selective excitation of a predetermined vibrational mode in CARS microscopy [Malinovskaya and Malinovsky, Opt. Lett. 32, 707 (2007)]. The method utilizes the chirp sign variation at the peak pulse amplitude and gives a robust adiabatic excitation of the desired vibrational mode. Using this method, we investigate the impact of coupling between vibrational modes in molecules on controllability of excitation of the CARS signal. We analyze two models of two coupled two-level systems (TLSs) having slightly different transitional frequencies. The first model, featuring degenerate ground states of the TLSs, gives robust adiabatic excitation and maximum coherence in the resonant TLS for positive value of the chirp. In the second model, implying nondegenerate ground states in the TLSs, a population distribution is observed in both TLSs, resulting in a lack of selectivity of excitation and low coherence. It is shown that the relative phase and coupling between the TLSs play an important role in optimizing coherence in the desired vibrational mode and suppressing unwanted transitions in CARS microscopy.

  18. A high-quality factor of 267 000 micromechanical silicon resonator utilizing TED-free torsional vibration mode

    Science.gov (United States)

    Nakamura, K.; Naito, Y.; Onishi, K.; Kawakatsu, H.

    2012-12-01

    In industrial applications of a micromechanical silicon resonator as a physical sensor, a high-quality factor Q and a low-temperature coefficient of Q (TCQ) are required for high sensitivity in a wide temperature range. Although the newly developed thin film encapsulation technique enables a beam to operate with low viscous damping in a vacuum cavity, the Q of a flexural vibration mode is limited by thermo-elastic damping (TED). We proposed a torsional beam resonator which features both a high Q and a low TCQ because theoretically the torsional vibration mode does not suffer from TED. From experiments, Q of 267 000 and TCQ of 1.4 for the 20 MHz torsional vibration mode were observed which were superior to those of the flexural mode. The pressure of the residual gas in the cavity of only 20 pl volume, which is one of the energy loss factors limiting the Q, was successfully estimated to be 1-14 Pa. Finally, the possibilities of improving the Q and the difference of the measured TCQ from a theoretical value were discussed.

  19. Effects of shape and dopant on structural, optical absorption, Raman, and vibrational properties of silver and copper quantum clusters: A density functional theory study

    International Nuclear Information System (INIS)

    Li Wei-Yin; Chen Fu-Yi

    2014-01-01

    We investigate the effects of shape and single-atom doping on the structural, optical absorption, Raman, and vibrational properties of Ag 13 , Ag 12 Cu 1 , Cu 13 , and Cu 12 Ag 1 clusters by using the (time-dependent) density functional theory. The results show that the most stable structures are cuboctahedron (COh) for Ag 13 and icosahedron (Ih) for Cu 13 , Ag 12 Cu 1core , and Cu 12 Ag 1sur . In the visible—near infrared optical absorption, the transitions consist of the interband and the intraband transitions. Moreover, red shifts are observed as follows: 1) clusters change from Ag 12 Cu 1core to Ag 13 to Ag 12 Cu 1sur with the same motifs, 2) the shapes of pure Ag 13 and Ag 12 Cu 1core clusters change from COh to Ih to decahedron (Dh), 3) the shape of Ag 12 Cu 1sur clusters changes from Ih to COh to Dh, and 4) the shapes of pure Cu 13 and Cu 12 Ag 1 clusters change from Ih to Dh to COh. All of the Raman and vibrational spectra exhibit many significant vibrational modes related to the shapes and the compositions of the clusters. The ranges of vibrational spectra of Ag 13 , Ag 12 Cu 1 or Cu 13 , and Cu 12 Ag 1 clusters become narrower and the vibrational intensities increase as the shape of the clusters changes from Ih to Dh to COh. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  20. Multimode vibration analysis with high-speed TV holography and a spatiotemporal 3D Fourier transform method.

    Science.gov (United States)

    Trillo, Cristina; Doval, Angel F; Mendoza-Santoyo, Fernando; Pérez-López, Carlos; de la Torre-Ibarra, Manuel; Deán, J Luis

    2009-09-28

    The combination of a high-speed TV holography system and a 3D Fourier-transform data processing is proposed for the analysis of multimode vibrations in plates. The out-of-plane displacement of the object under generic vibrational excitation is resolved in time by the fast acquisition rate of a high-speed camera, and recorded in a sequence of interferograms with spatial carrier. A full-field temporal history of the multimode vibration is thus obtained. The optical phase of the interferograms is extracted and subtracted from the phase of a reference state to yield a sequence of optical phase-change maps. Each map represents the change undergone by the object between any given state and the reference state. The sequence of maps is a 3D array of data (two spatial dimensions plus time) that is processed with a 3D Fourier-transform algorithm. The individual vibration modes are separated in the 3D frequency space due to their different vibration frequencies and, to a lesser extent, to the different spatial frequencies of the mode shapes. The contribution of each individual mode (or indeed the superposition of several modes) to the dynamic behaviour of the object can then be separated by means of a bandpass filter (or filters). The final output is a sequence of complex-valued maps that contain the full-field temporal history of the selected mode (or modes) in terms of its mechanical amplitude and phase. The proof-of-principle of the technique is demonstrated with a rectangular, fully clamped, thin metal plate vibrating simultaneously in several of its natural resonant frequencies under white-noise excitation.

  1. Stretching dependence of the vibration modes of a single-molecule Pt-H-2-Pt bridge

    DEFF Research Database (Denmark)

    Djukic, D.; Thygesen, Kristian Sommer; Untiedt, C.

    2005-01-01

    isotope substitution is obtained. The stretching dependence for each of the modes allows uniquely classifying them as longitudinal or transversal modes. The interpretation of the experiment in terms of a Pt-H-2-Pt bridge is verified by density-functional theory calculations for the stability, vibrational...

  2. Laterally Vibrating Resonator Based Elasto-Optic Modulation in Aluminum Nitride

    Science.gov (United States)

    2016-08-15

    the adjoining test setup used to probe the devices. Following the design of a laterally vibrating piezoelectric contour...licenses/by/4.0/). [http://dx.doi.org/10.1063/1.4945356] The interaction of acoustic waves with light provides a useful resource to perform optical signal...recent years, several types of acousto-optic interactions have been demonstrated in a wide va- riety of devices, including the use of

  3. Employing optical code division multiple access technology in the all fiber loop vibration sensor system

    Science.gov (United States)

    Tseng, Shin-Pin; Yen, Chih-Ta; Syu, Rong-Shun; Cheng, Hsu-Chih

    2013-12-01

    This study proposes a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) framework to access the vibration frequency of a test object on the all fiber loop vibration sensor (AFLVS). Each user possesses an individual SAC, and fiber Bragg grating (FBG) encoders/decoders using multiple FBG arrays were adopted, providing excellent orthogonal properties in the frequency domain. The system also mitigates multiple access interference (MAI) among users. When an optical fiber is bent to a point exceeding the critical radius, the fiber loop sensor becomes sensitive to external physical parameters (e.g., temperature, strain, and vibration). The AFLVS involves placing a fiber loop with a specific radius on a designed vibration platform.

  4. Dynamics of Nonlinear Excitation of the High-Order Mode in a Single-Mode Step-Index Optical Fiber

    Science.gov (United States)

    Burdin, V.; Bourdine, A.

    2018-04-01

    This work is concerned with approximate model of higher-order mode nonlinear excitation in a singlemode silica optical fiber. We present some results of simulation for step-index optical fiber under femtosecond optical pulse launching, which confirm ability of relatively stable higher-order mode excitation in such singlemode optical fiber over sufficiently narrow range of launched optical power variation.

  5. Blade Vibration Measurement System for Characterization of Closely Spaced Modes and Mistuning, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — There are several ongoing challenges in non-contacting blade vibration and stress measurement systems that can address closely spaced modes and blade-to-blade...

  6. Fused-fiber-based 3-dB mode insensitive power splitters for few-mode optical fiber networks

    Science.gov (United States)

    Ren, Fang; Huang, Xiaoshan; Wang, Jianping

    2017-11-01

    We propose a 3-dB mode insensitive power splitter (MIPS) capable of broadcasting and combining optical signals. It is fabricated with two identical few-mode fibers (FMFs) by a heating and pulling technique. The mode-dependent power transfer characteristic as a function of pulling length is investigated. For exploiting its application, we experimentally demonstrate both FMF-based transmissive and reflective star couplers consisting of multiple 3-dB mode insensitive power splitters, which perform broadcasting and routing signals in few-mode optical fiber networks such as mode-division multiplexing (MDM) local area networks using star topology. For experimental demonstration, optical on-off keying signals at 10 Gb/s carried on three spatial modes are successfully processed with open and clear eye diagrams. Measured bit error ratio results show reasonable power penalties. It is found that a reflective star coupler in MDM networks can reduce half of the total amount of required fibers comparing to that of a transmissive star coupler. This MIPS is more efficient, more reliable, more flexible, and more cost-effective for future expansion and application in few-mode optical fiber networks.

  7. A MEMS Resonant Sensor to Measure Fluid Density and Viscosity under Flexural and Torsional Vibrating Modes

    Directory of Open Access Journals (Sweden)

    Libo Zhao

    2016-06-01

    Full Text Available Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m3 to 900 kg/m3 and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.

  8. Experimental demonstration of time- and mode-division multiplexed passive optical network

    Science.gov (United States)

    Ren, Fang; Li, Juhao; Tang, Ruizhi; Hu, Tao; Yu, Jinyi; Mo, Qi; He, Yongqi; Chen, Zhangyuan; Li, Zhengbin

    2017-07-01

    A time- and mode-division multiplexed passive optical network (TMDM-PON) architecture is proposed, in which each optical network unit (ONU) communicates with the optical line terminal (OLT) independently utilizing both different time slots and switched optical linearly polarized (LP) spatial modes. Combination of a mode multiplexer/demultiplexer (MUX/DEUX) and a simple N × 1 optical switch is employed to select the specific LP mode in each ONU. A mode-insensitive power splitter is used for signal broadcast/combination between OLT and ONUs. We theoretically propose a dynamic mode and time slot assignment scheme for TMDM-PON based on inter-ONU priority rating, in which the time delay and packet loss ratio's variation tendency are investigated by simulation. Moreover, we experimentally demonstrate 2-mode TMDM-PON transmission over 10 km FMF with 10-Gb/s on-off keying (OOK) signal and direct detection.

  9. Vibrational optical activity principles and applications

    CERN Document Server

    Nafie, Laurence A

    2011-01-01

    This unique book stands as the only comprehensive introduction to vibrational optical activity (VOA) and is the first single book that serves as a complete reference for this relatively new, but increasingly important area of molecular spectroscopy. Key features:A single-source reference on this topic that introduces, describes the background and foundation of this area of spectroscopy.Serves as a guide on how to use it to carry out applications with relevant problem solving.Depth and breadth of the subject is presented in a logical, complete and progressive fashion. A

  10. Testing ultrafast mode-locking at microhertz relative optical linewidth.

    Science.gov (United States)

    Martin, Michael J; Foreman, Seth M; Schibli, T R; Ye, Jun

    2009-01-19

    We report new limits on the phase coherence of the ultrafast mode-locking process in an octave-spanning Ti:sapphire comb.We find that the mode-locking mechanism correlates optical phase across a full optical octave with less than 2.5 microHZ relative linewidth. This result is at least two orders of magnitude below recent predictions for quantum-limited individual comb-mode linewidths, verifying that the mode-locking mechanism strongly correlates quantum noise across the comb spectrum.

  11. Testing ultrafast mode-locking at microhertz relative optical linewidth

    OpenAIRE

    Martin, Michael J.; Foreman, Seth M.; Schibli, T. R.; Ye, Jun

    2008-01-01

    We report new limits on the phase coherence of the ultrafast mode-locking process in an octave-spanning Ti:sapphire comb. We find that the mode-locking mechanism correlates optical phase across a full optical octave with less than 2.5 micro Hz relative linewidth. This result is at least two orders of magnitude below recent predictions for quantum-limited individual comb-mode linewidths, verifying that the mode-locking mechanism strongly correlates quantum noise across the comb spectrum.

  12. Atomistic theory for the damping of vibrational modes in monoatomic gold chains

    DEFF Research Database (Denmark)

    Engelund, Mads; Brandbyge, Mads; Jauho, Antti-Pekka

    2009-01-01

    We develop a computational method for evaluating the damping of vibrational modes in monatomic metallic chains suspended between bulk crystals under external strain. The damping is due to the coupling between the chain and contact modes and the phonons in the bulk substrates. The geometry of the ...... in the harmonic damping is possible even for relatively small changes in the strain. Such detailed insight is necessary for a quantitative analysis of damping in metallic atomic chains and in explaining the rich phenomenology seen in the experiments....

  13. Calculations of lattice vibrational mode lifetimes using Jazz: a Python wrapper for LAMMPS

    International Nuclear Information System (INIS)

    Gao, Y; Wang, H; Daw, M S

    2015-01-01

    Jazz is a new python wrapper for LAMMPS [1], implemented to calculate the lifetimes of vibrational normal modes based on forces as calculated for any interatomic potential available in that package. The anharmonic character of the normal modes is analyzed via the Monte Carlo-based moments approximation as is described in Gao and Daw [2]. It is distributed as open-source software and can be downloaded from the website http://jazz.sourceforge.net/. (paper)

  14. Calculations of lattice vibrational mode lifetimes using Jazz: a Python wrapper for LAMMPS

    Science.gov (United States)

    Gao, Y.; Wang, H.; Daw, M. S.

    2015-06-01

    Jazz is a new python wrapper for LAMMPS [1], implemented to calculate the lifetimes of vibrational normal modes based on forces as calculated for any interatomic potential available in that package. The anharmonic character of the normal modes is analyzed via the Monte Carlo-based moments approximation as is described in Gao and Daw [2]. It is distributed as open-source software and can be downloaded from the website http://jazz.sourceforge.net/.

  15. Structural, optical and vibrational properties of Cr2O3 with ferromagnetic and antiferromagnetic order: A combined experimental and density functional theory study

    Science.gov (United States)

    Larbi, T.; Ouni, B.; Gantassi, A.; Doll, K.; Amlouk, M.; Manoubi, T.

    2017-12-01

    Chromium oxide (Cr2O3) thin films have been synthesized on glass substrates by the spray pyrolysis technique. The structural, morphological and optical properties of the sample have been studied by X-ray diffraction (XRD), Raman spectroscopy, FTIR spectroscopy, scanning probe microscopy and UV-vis spectroscopy respectively. X-ray diffraction results reveal that as deposited film is polycrystalline with a rhombohedral corundum structure and a preferential orientation of the crystallites along the (1 0 4) direction. IR and Raman spectra were recorded in the 100-900 cm-1 range and the observed modes were analysed and assigned to different normal modes of vibration. The direct optical band gap energy value calculated from the transmittance spectra of as-deposited thin film is about 3.38 eV. We employ first principles calculations based on density functional theory (DFT) with the B3LYP hybrid functional and a coupled perturbed Hartree-Fock/Kohn-Sham approach (CPHF/KS). We study the electronic structure, optimum geometry, and IR and Raman spectra of ferromagnetically and antiferromagnetically ordered Cr2O3. The computed results are consistent with the experimental measurements, and provide complete vibrational assignment, for the characterization of Cr2O3 thin film materials which can be used in photocatalysis and gas sensors.

  16. Research of hydroelectric generating set low-frequency vibration monitoring system based on optical fiber sensing

    Science.gov (United States)

    Min, Li; Zhang, Xiaolei; Zhang, Faxiang; Sun, Zhihui; Li, ShuJuan; Wang, Meng; Wang, Chang

    2017-10-01

    In order to satisfy hydroelectric generating set low-frequency vibration monitoring, the design of Passive low-frequency vibration monitoring system based on Optical fiber sensing in this paper. The hardware of the system adopts the passive optical fiber grating sensor and unbalanced-Michelson interferometer. The software system is used to programming by Labview software and finishing the control of system. The experiment show that this system has good performance on the standard vibration testing-platform and it meets system requirements. The frequency of the monitoring system can be as low as 0.2Hz and the resolution is 0.01Hz.

  17. a Study of Vibrational Mode Coupling in 2-FLUOROETHANOL and 1,2-DIFLUOROETHANE Using High-Resolution Infrared Spectroscopy.

    Science.gov (United States)

    Mork, Steven Wayne

    High resolution infrared spectroscopy was used to examine intramolecular vibrational interactions in 2 -fluoroethanol (2FE) and 1,2-difluoroethane (DFE). A high resolution infrared spectrophotometer capable of better than 10 MHz spectral resolution was designed and constructed. The excitation source consists of three lasers: an argon-ion pumped dye laser which pumps a color -center laser. The infrared beam from the color-center laser is used to excite sample molecules which are rotationally and vibrationally cooled in a supersonic molecular beam. Rovibrational excitation of the sample molecules is detected by monitoring the kinetic energy of the molecular beam with a bolometer. The high resolution infrared spectrum of 2FE was collected and analyzed over the 2977-2990 cm^ {-1}^ectral region. This region contains the asymmetric CH stretch on the fluorinated carbon. The spectrum revealed extensive perturbations in the rotational fine structure. Analysis of these perturbations has provided a quantitative measure of selective vibrational mode coupling between the C-H stretch and its many neighboring dark vibrational modes. Interestingly, excitation of the C-H stretch is known to induce a photoisomerization reaction between 2FE's Gg^' and Tt conformers. Implications of the role of mode coupling in the reaction mechanism are also addressed. Similarly, the high resolution infrared spectrum of DFE was collected and analyzed over the 2978-2996 cm ^{-1}^ectral region. This region contains the symmetric combination of asymmetric C-H stretches in DFE. Perturbations in the rotational fine structure indicate vibrational mode coupling to a single dark vibrational state. The dark state is split by approximately 19 cm^{-1} due to tunneling between two identical gauche conformers. The coupling mechanism is largely anharmonic with a minor component of B/C-plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. The coupled vibrational

  18. Measurement of correlations between low-frequency vibrational modes and particle rearrangements in quasi-two-dimensional colloidal glasses.

    Science.gov (United States)

    Chen, Ke; Manning, M L; Yunker, Peter J; Ellenbroek, Wouter G; Zhang, Zexin; Liu, Andrea J; Yodh, A G

    2011-09-02

    We investigate correlations between low-frequency vibrational modes and rearrangements in two-dimensional colloidal glasses composed of thermosensitive microgel particles, which readily permit variation of the sample packing fraction. At each packing fraction, the particle displacement covariance matrix is measured and used to extract the vibrational spectrum of the "shadow" colloidal glass (i.e., the particle network with the same geometry and interactions as the sample colloid but absent damping). Rearrangements are induced by successive, small reductions in the packing fraction. The experimental results suggest that low-frequency quasilocalized phonon modes in colloidal glasses, i.e., modes that present low energy barriers for system rearrangements, are spatially correlated with rearrangements in this thermal system.

  19. Optical Spring Effect in Micro-Bubble Resonators and Its Application for the Effective Mass Measurement of Optomechanical Resonant Mode

    OpenAIRE

    Zhenmin Chen; Xiang Wu; Liying Liu; Lei Xu

    2017-01-01

    In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs). To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE) in MBRs. This approach is demonstrated and applied to analyze the effective mass of hollow MBRs and liquid-filled MBRs, respectively. It is found that the liquid-filled MBRs has significantly stronger OSE and a less effective mass than hollow MBRs, both of the...

  20. Coherent dynamics of the localized vibrational modes of hydrogen in CaF2

    NARCIS (Netherlands)

    Wells, J. P. R.; Rella, C. W.; Bradley, I. V.; Galbraith, I.; Pidgeon, C. R.

    2000-01-01

    We report the observation of giant quantum coherence effects in the localized modes of ionized hydrogen in synthetic fluorite. Infrared free induction decay experiments on the substitutional H+ center thew dramatic modulations at negative delay times due to interference between multiple vibrational

  1. Coupling analysis of energy conversion in multi-mode vibration structural control using a synchronized switch damping method

    International Nuclear Information System (INIS)

    Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Inman, Daniel

    2012-01-01

    Modal coupling is an important issue in the analysis and control of structural systems with multi-degrees of freedom (MDOF). In this paper, modal coupling induced by energy conversion in the structural control of an MDOF system using a synchronized switch damping method is investigated theoretically and validated numerically. In the analysis, it is supposed that the voltage on the piezoelectric actuator is switched at the displacement extrema of a given mode. Two types of coupling in energy conversion are considered. The first is whether the switching action based on one mode induces energy conversion of the other modes. The second is whether the vibration of one mode affects the energy conversion of the other modes. The results indicate that the modal coupling in energy conversion is very complicated. In most cases the switching action based on one mode does induce energy conversion of another mode, but the efficiency depends on the frequency ratio of the two modes. The vibration of one mode affects the energy conversion of another mode only when the frequency ratio of the two modes takes some special values. Discussions are also given on the potential application of the theoretical results in the design of an energy harvesting device. (paper)

  2. Predicting plasticity with soft vibrational modes: from dislocations to glasses.

    Science.gov (United States)

    Rottler, Jörg; Schoenholz, Samuel S; Liu, Andrea J

    2014-04-01

    We show that quasilocalized low-frequency modes in the vibrational spectrum can be used to construct soft spots, or regions vulnerable to rearrangement, which serve as a universal tool for the identification of flow defects in solids. We show that soft spots not only encode spatial information, via their location, but also directional information, via directors for particles within each soft spot. Single crystals with isolated dislocations exhibit low-frequency phonon modes that localize at the core, and their polarization pattern predicts the motion of atoms during elementary dislocation glide in two and three dimensions in exquisite detail. Even in polycrystals and disordered solids, we find that the directors associated with particles in soft spots are highly correlated with the direction of particle displacements in rearrangements.

  3. Hypersonic vibrations of Ag@SiO2 (cubic core)-shell nanospheres.

    Science.gov (United States)

    Sun, Jing Ya; Wang, Zhi Kui; Lim, Hock Siah; Ng, Ser Choon; Kuok, Meng Hau; Tran, Toan Trong; Lu, Xianmao

    2010-12-28

    The intriguing optical and catalytic properties of metal-silica core-shell nanoparticles, inherited from their plasmonic metallic cores together with the rich surface chemistry and increased stability offered by their silica shells, have enabled a wide variety of applications. In this work, we investigate the confined vibrational modes of a series of monodisperse Ag@SiO(2) (cubic core)-shell nanospheres synthesized using a modified Stöber sol-gel method. The particle-size dependence of their mode frequencies has been mapped by Brillouin light scattering, a powerful tool for probing hypersonic vibrations. Unlike the larger particles, the observed spheroidal-like mode frequencies of the smaller ones do not scale with inverse diameter. Interestingly, the onset of the deviation from this linearity occurs at a smaller particle size for higher-energy modes than for lower-energy ones. Finite element simulations show that the mode displacement profiles of the Ag@SiO(2) core-shells closely resemble those of a homogeneous SiO(2) sphere. Simulations have also been performed to ascertain the effects that the core shape and the relative hardness of the core and shell materials have on the vibrations of the core-shell as a whole. As the vibrational modes of a particle have a bearing on its thermal and mechanical properties, the findings would be of value in designing core-shell nanostructures with customized thermal and mechanical characteristics.

  4. Single-mode glass waveguide technology for optical interchip communication on board level

    Science.gov (United States)

    Brusberg, Lars; Neitz, Marcel; Schröder, Henning

    2012-01-01

    The large bandwidth demand in long-distance telecom networks lead to single-mode fiber interconnects as result of low dispersion, low loss and dense wavelength multiplexing possibilities. In contrast, multi-mode interconnects are suitable for much shorter lengths up to 300 meters and are promising for optical links between racks and on board level. Active optical cables based on multi-mode fiber links are at the market and research in multi-mode waveguide integration on board level is still going on. Compared to multi-mode, a single-mode waveguide has much more integration potential because of core diameters of around 20% of a multi-mode waveguide by a much larger bandwidth. But light coupling in single-mode waveguides is much more challenging because of lower coupling tolerances. Together with the silicon photonics technology, a single-mode waveguide technology on board-level will be the straight forward development goal for chip-to-chip optical interconnects integration. Such a hybrid packaging platform providing 3D optical single-mode links bridges the gap between novel photonic integrated circuits and the glass fiber based long-distance telecom networks. Following we introduce our 3D photonic packaging approach based on thin glass substrates with planar integrated optical single-mode waveguides for fiber-to-chip and chip-to-chip interconnects. This novel packaging approach merges micro-system packaging and glass integrated optics. It consists of a thin glass substrate with planar integrated singlemode waveguide circuits, optical mirrors and lenses providing an integration platform for photonic IC assembly and optical fiber interconnect. Thin glass is commercially available in panel and wafer formats and characterizes excellent optical and high-frequency properties. That makes it perfect for microsystem packaging. The paper presents recent results in single-mode waveguide technology on wafer level and waveguide characterization. Furthermore the integration in a

  5. Low-bending loss and single-mode operation in few-mode optical fiber

    Science.gov (United States)

    Yin, Ping; Wang, Hua; Chen, Ming-Yang; Wei, Jin; Cai, Zhi-Min; Li, Lu-Ming; Yang, Ji-Hai; Zhu, Yuan-Feng

    2016-10-01

    The technique of eliminating the higher-order modes in a few-mode optical fiber is proposed. The fiber is designed with a group of defect modes in the cladding. The higher-order modes in the fiber can be eliminated by bending the fiber to induce strong coupling between the defect modes and the higher-order modes. Numerical simulation shows the bending losses of the LP01 mode are lower than 1.5×10-4 dB/turn for the wavelength shorter than 1.625 μm. The proposed fiber can be bent multiple turns at small bending radius which are preferable for FTTH related applications.

  6. Measuring a Fiber-Optic Delay Line Using a Mode-Locked Laser

    Science.gov (United States)

    Tu, Meirong; McKee, Michael R.; Pak, Kyung S.; Yu, Nan

    2010-01-01

    The figure schematically depicts a laboratory setup for determining the optical length of a fiber-optic delay line at a precision greater than that obtainable by use of optical time-domain reflectometry or of mechanical measurement of length during the delay-line-winding process. In this setup, the delay line becomes part of the resonant optical cavity that governs the frequency of oscillation of a mode-locked laser. The length can then be determined from frequency-domain measurements, as described below. The laboratory setup is basically an all-fiber ring laser in which the delay line constitutes part of the ring. Another part of the ring - the laser gain medium - is an erbium-doped fiber amplifier pumped by a diode laser at a wavelength of 980 nm. The loop also includes an optical isolator, two polarization controllers, and a polarizing beam splitter. The optical isolator enforces unidirectional lasing. The polarization beam splitter allows light in only one polarization mode to pass through the ring; light in the orthogonal polarization mode is rejected from the ring and utilized as a diagnostic output, which is fed to an optical spectrum analyzer and a photodetector. The photodetector output is fed to a radio-frequency spectrum analyzer and an oscilloscope. The fiber ring laser can generate continuous-wave radiation in non-mode-locked operation or ultrashort optical pulses in mode-locked operation. The mode-locked operation exhibited by this ring is said to be passive in the sense that no electro-optical modulator or other active optical component is used to achieve it. Passive mode locking is achieved by exploiting optical nonlinearity of passive components in such a manner as to obtain ultra-short optical pulses. In this setup, the particular nonlinear optical property exploited to achieve passive mode locking is nonlinear polarization rotation. This or any ring laser can support oscillation in multiple modes as long as sufficient gain is present to overcome

  7. Enhanced vibration diagnostics using vibration signature analysis

    International Nuclear Information System (INIS)

    Ahmed, S.; Shehzad, K.; Zahoor, Y.; Mahmood, A.; Bibi, A.

    2001-01-01

    Symptoms will appear in equipment, as well as in human beings. when 'suffering from sickness. Symptoms of abnormality in equipment are vibration, noise, deformation, temperature, pressure, electric current, crack, wearing, leakage etc. these are called modes of failure. If the mode of failure is vibration then the vibration signature analysis can be effectively used in order to diagnose the machinery problems. Much valuable information is contained within these vibration 'Spectra' or 'Signatures' but is only of use if the analyst can unlock its 'Secrets'. This paper documents a vibration problem in the motor of a centrifugal pump (Type ETA). It focuses mainly on the roll of modern vibration monitoring system in problem analysis. The problem experienced was the motor unstability and noise due to high vibration. Using enhanced vibration signature data, the problem was analyzed. which suggested that the rotor eccentricity was the cause of excessive noise and vibration in the motor. In conclusion, advanced electronic monitoring and diagnostic systems provide powerful information for machine's condition assessment and problem analysis. Appropriate interpretation and use of this information is important for accurate and effective vibration analysis. (author)

  8. The vibration compensation system for ARGOS

    Science.gov (United States)

    Peter, D.; Gaessler, W.; Borelli, J.; Kulas, M.

    2011-09-01

    For every adaptive optics system telescope vibrations can strongly reduce the performance. This is true for the receiver part of the system i.e. the telescope and wave front sensor part as well as for the transmitter part in the case of a laser guide star system. Especially observations in deep fields observed with a laser guide star system without any tip-tilt star will be greatly spoiled by telescope vibrations. The ARGOS GLAO system actually being built for the LBT aims to implement this kind of mode where wave front correction will rely purely on signals from the laser beacons. To remove the vibrations from the uplink path a vibration compensation system will be installed. This system uses accelerometers to measure the vibrations and corrects their effect with a small fast tip-tilt mirror. The controller of the system is built based on the assumption that the vibrations take place at a few distinct frequencies. Here I present a lab set-up of this system and show first results of the performance.

  9. Orientations of nonlocal vibrational modes from combined experimental and theoretical sum frequency spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chase, Hilary M.; Chen, Shunli; Fu, Li; Upshur, Mary Alice; Rudshteyn, Benjamin; Thomson, Regan J.; Wang, Hong-Fei; Batista, Victor S.; Geiger, Franz M.

    2017-09-01

    Inferring molecular orientations from vibrational sum frequency generation (SFG) spectra is challenging in polarization combinations that result in low signal intensities, or when the local point group symmetry approximation fails. While combining experiments with density functional theory (DFT) could overcome this problem, the scope of the combined method has yet to be established. Here, we assess its feasibility of determining the distributions of molecular orientations for one monobasic ester, two epoxides and three alcohols at the vapor/fused silica interface. We find that molecular orientations of nonlocal vibrational modes cannot be determined using polarization-resolved SFG measurements alone.

  10. On-line Vibration Diagnostics of the Optical Elements at BL-28 of the Photon Factory

    International Nuclear Information System (INIS)

    Maruyama, T.; Kashiwagi, T.; Kikuchi, T.; Toyoshima, A.; Kubota, M.; Ono, K.

    2007-01-01

    We have analyzed the data of encoders attached to optical elements and developed an on-line vibration diagnostics system of the monochromator. After eliminating the vibration source we have been able to improve the performance of the monochromator

  11. Modelling and processing of data from a fibre-optic sensor of vibrations

    International Nuclear Information System (INIS)

    Morawski, R Z; Makowski, P L; Michalik, L; Domanski, A W

    2010-01-01

    A new technique of vibration sensing, based on a polarimetric fibre-optic strain sensor, is presented; it is designed for localisation of multiple sources of disturbances in a broad spectrum without using fibre gratings. A mathematical model of the sensor is used for development of a variational method for estimation of amplitudes of component vibrations on the basis of noisy samples of the voltage at the output of the sensor.

  12. Segmentation of a Vibro-Shock Cantilever-Type Piezoelectric Energy Harvester Operating in Higher Transverse Vibration Modes

    Directory of Open Access Journals (Sweden)

    Darius Zizys

    2015-12-01

    Full Text Available The piezoelectric transduction mechanism is a common vibration-to-electric energy harvesting approach. Piezoelectric energy harvesters are typically mounted on a vibrating host structure, whereby alternating voltage output is generated by a dynamic strain field. A design target in this case is to match the natural frequency of the harvester to the ambient excitation frequency for the device to operate in resonance mode, thus significantly increasing vibration amplitudes and, as a result, energy output. Other fundamental vibration modes have strain nodes, where the dynamic strain field changes sign in the direction of the cantilever length. The paper reports on a dimensionless numerical transient analysis of a cantilever of a constant cross-section and an optimally-shaped cantilever with the objective to accurately predict the position of a strain node. Total effective strain produced by both cantilevers segmented at the strain node is calculated via transient analysis and compared to the strain output produced by the cantilevers segmented at strain nodes obtained from modal analysis, demonstrating a 7% increase in energy output. Theoretical results were experimentally verified by using open-circuit voltage values measured for the cantilevers segmented at optimal and suboptimal segmentation lines.

  13. The optical, vibrational, structural and elasto-optic properties of Zn_0_._2_5Cd_0_._7_5S_ySe_1_-_y quaternary alloys

    International Nuclear Information System (INIS)

    Paliwal, U.; Swarkar, C. B.; Sharma, M. D.; Joshi, K. B.

    2016-01-01

    The optical, vibrational, structural and elasto-optic properties of quaternary II-VI alloys Zn_0_._2_5Cd_0_._7_5S_0_._2_5Se_0_._7_5, Zn_0_._2_5Cd_0_._7_5S_0_._5_0Se_0_._5_0 and Zn_0_._2_5Cd_0_._7_5S_0_._7_5Se_0_._2_5 are presented. Within the empirical pseudopotential method (EPM) the disorder effects are modeled via modified virtual crystal approximation (MVCA). The computed bandgaps and the refined form factors are utilized to evaluate optical, vibrational, structural and elasto-optic properties. The refractive index (n), static (ε_0) and high frequency dielectric (ε_∞) constants are calculated to reveal optical behavior of alloys. The longitudinal ω_L_O(0) and transverse ω_T_O(0) optical frequencies are obtained to see vibrational characteristics. Moreover, the elastic constants (c_i_j) and bulk moduli (B) are computed by combining the EPM with Harrison bond orbital model. The elasto-optic nature of alloys is examined by computing the photo-elastic constants. These values are significant with regard to the opto-electronic applications especially when no experimental data are available on this system.

  14. Nonlinear normal vibration modes in the dynamics of nonlinear elastic systems

    International Nuclear Information System (INIS)

    Mikhlin, Yu V; Perepelkin, N V; Klimenko, A A; Harutyunyan, E

    2012-01-01

    Nonlinear normal modes (NNMs) are a generalization of the linear normal vibrations. By the Kauderer-Rosenberg concept in the regime of the NNM all position coordinates are single-values functions of some selected position coordinate. By the Shaw-Pierre concept, the NNM is such a regime when all generalized coordinates and velocities are univalent functions of a couple of dominant (active) phase variables. The NNMs approach is used in some applied problems. In particular, the Kauderer-Rosenberg NNMs are analyzed in the dynamics of some pendulum systems. The NNMs of forced vibrations are investigated in a rotor system with an isotropic-elastic shaft. A combination of the Shaw-Pierre NNMs and the Rauscher method is used to construct the forced NNMs and the frequency responses in the rotor dynamics.

  15. Vibrational modes and strain in GaN/AlN quantum dot stacks: dependence on spacer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Fresneda, J.; Cros, A.; Llorens, J.M.; Garcia-Cristobal, A.; Cantarero, A. [Institut de Ciencia del Materials, Universitat de Valencia, 46071 Valencia (Spain); Amstatt, B.; Bellet-Amalric, E.; Daudin, B. [CEA-CNRS Group, Nanophysique et Semiconducteurs, DRFMC/SP2M/PSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France)

    2007-06-15

    We have investigated the influence of spacer thickness on the vibrational and strain characteristics of GaN/AlN quantum dot multilayers (QD). The Raman shift corresponding to the E{sub 2h} vibrational mode related to the QDs has been analyzed for AlN thicknesses ranging from 4.4 nm to 13 nm, while the amount of GaN deposited in each layer remained constant from sample to sample. It is shown that there is a rapid blue shift of the GaN vibrational mode with spacer thickness when its value is smaller than 7 nm while it remains almost constant for thicker spacers. A rapid increase of the Raman line-width in the thicker samples is also observed. The experimental behavior is discussed in comparison with the results of a theoretical model for the strain in the QDs. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Spiral Transformation for High-Resolution and Efficient Sorting of Optical Vortex Modes

    Science.gov (United States)

    Wen, Yuanhui; Chremmos, Ioannis; Chen, Yujie; Zhu, Jiangbo; Zhang, Yanfeng; Yu, Siyuan

    2018-05-01

    Mode sorting is an essential function for optical multiplexing systems that exploit the orthogonality of the orbital angular momentum mode space. The familiar log-polar optical transformation provides a simple yet efficient approach whose resolution is, however, restricted by a considerable overlap between adjacent modes resulting from the limited excursion of the phase along a complete circle around the optical vortex axis. We propose and experimentally verify a new optical transformation that maps spirals (instead of concentric circles) to parallel lines. As the phase excursion along a spiral in the wave front of an optical vortex is theoretically unlimited, this new optical transformation can separate orbital angular momentum modes with superior resolution while maintaining unity efficiency.

  17. Qualitative and quantitative approach towards the molecular understanding of structural, vibrational and optical features of urea ninhydrin monohydrate

    Energy Technology Data Exchange (ETDEWEB)

    Sasikala, V. [Department of Physics, Bishop Moore College, Mavelikara, Alappuzha, Kerala 690110 (India); Sajan, D., E-mail: drsajanbmc@gmail.com [Department of Physics, Bishop Moore College, Mavelikara, Alappuzha, Kerala 690110 (India); Chaitanya, K. [Department of Chemistry, Nanjing University of Science and Technology, Xialingwei 200, Nanjing (China); Sundius, Tom [Department of Physics, University of Helsinki (Finland); Devi, T. Uma [Department of Physics, Government Arts College for Women (Autonomous), Pudukottai (India)

    2017-04-15

    In this study, single crystals of urea ninhydrin monohydrate (UNMH) have been grown by slow evaporation method. The grown crystals were characterized by FT-IR, FT-Raman and UV-Vis-NIR spectroscopies. The Kurtz and Perry powder method was employed to confirm the near-zero SHG efficiency of the as-grown centrosymmetric UNMH crystal. The third order nonlinearity of the crystal has been studied by the open aperture Z-scan method. The nonlinear absorption coefficient is calculated and the potentiality of UNMH in optical limiting applications is identified. The molecular geometry and the origin of optical non-linearity at the molecular level have been investigated by the density functional theory. The normal coordinate analysis was carried out to assign the molecular vibrational modes. Vibrational spectral studies confirms the presence of weak O-H⋯O and moderate O-H⋯O type hydrogen bonds in the molecule as well as O-H⋯O, N-H⋯O and blue-shifted C-H⋯O type H-bonds in the crystal. The intramolecular charge transfer interactions and the electronic absorption mechanisms have been discussed. The static and the dynamic values of hyperpolarizabilities for UNMH were estimated theoretically by DFT methods. - Highlights: • Molecular geometric and NBO interaction features of UNMH were analyzed. • Vibrational spectral features and types of H-bonding in isolated gaseous phase molecule were discussed. • Electronic absorption maxima of different phases of UNMH were found out. • The non-linear absorption behaviour of UNMH is investigated using z-scan. • First- and second- order hyperpolarizability values were estimated theoretically.

  18. Power enhancing by reversing mode sequence in tuned mass-spring unit attached vibration energy harvester

    Directory of Open Access Journals (Sweden)

    Jae Eun Kim

    2013-07-01

    Full Text Available We propose a vibration energy harvester consisting of an auxiliary frequency-tuned mass unit and a piezoelectric vibration energy harvesting unit for enhancing output power. The proposed integrated system is so configured that its out-of-phase mode can appear at the lowest eigenfrequency unlike in the conventional system using a tuned unit. Such an arrangement makes the resulting system distinctive: enhanced output power at or near the target operating frequency and very little eigenfrequency separation, not observed in conventional eigenfrequency-tuned vibration energy harvesters. The power enhancement of the proposed system is theoretically examined with and without tip mass normalization or footprint area normalization.

  19. SBIR Grant:No-Vibration Agile Cryogenic Optical Refrigerator

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, Richard

    2013-04-09

    Optical refrigeration is currently the only all-solid-state cryocooling technology that has been demonstrated. Optical cryocoolers are devices that use laser light to cool small crystal or glass cooling elements. The cooling element absorbs the laser light and reradiates it at higher energy, an example of anti-Stokes fluorescence. The dif-ference between the energy of the outgoing and incoming light comes from the thermal energy of the cooling element, which in turn becomes colder. Entitled No-Vibration Agile Cryocoolers using Optical Refrigeration, this Phase I proposal directly addressed the continued development of the optical refrigerator components necessary to transition this scientific breakthrough into National Nu-clear Security Administration (NNSA) sensor applications in line with the objectives of topic 50b. ThermoDynamic Films LLC (TDF), in collaboration with the University of New Mexico (UNM), cooled an optical-refrigerator cooling element comprised of an ytterbium-doped yttrium lithium fluoride (Yb:YLF) crystal from room tempera-ture to 123 K with about 2% efficiency. This is the world record in optical refrigera-tion and an important step toward revolutionizing cryogenic systems for sensor ap-plications. During this period, they also designed and analyzed the crucial elements of a prototype optical refrigerator including the thermal link that connects the cool-ing element with the load.

  20. Robust fiber optic flexure sensor exploiting mode coupling in few-mode fiber

    Science.gov (United States)

    Nelsen, Bryan; Rudek, Florian; Taudt, Christopher; Baselt, Tobias; Hartmann, Peter

    2015-05-01

    Few-mode fiber (FMF) has become very popular for use in multiplexing telecommunications data over fiber optics. The simplicity of producing FMF and the relative robustness of the optical modes, coupled with the simplicity of reading out the information make this fiber a natural choice for communications. However, little work has been done to take advantage of this type of fiber for sensors. Here, we demonstrate the feasibility of using FMF properties as a mechanism for detecting flexure by exploiting mode coupling between modes when the cylindrical symmetry of the fiber is perturbed. The theoretical calculations shown here are used to understand the coupling between the lowest order linearly polarized mode (LP01) and the next higher mode (LP11x or LP11y) under the action of bending. Twisting is also evaluated as a means to detect flexure and was determined to be the most reliable and effective method when observing the LP21 mode. Experimental results of twisted fiber and observations of the LP21 mode are presented here. These types of fiber flexure sensors are practical in high voltage, high magnetic field, or high temperature medical or industrial environments where typical electronic flexure sensors would normally fail. Other types of flexure measurement systems that utilize fiber, such as Rayleigh back-scattering [1], are complicated and expensive and often provide a higher-than necessary sensitivity for the task at hand.

  1. Active material, optical mode and cavity impact on nanoscale electro-optic modulation performance

    Science.gov (United States)

    Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

    2017-10-01

    Electro-optic modulation is a key function in optical data communication and possible future optical compute engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While a variety of high-performance modulators have been demonstrated, no comprehensive picture of what factors are most responsible for high performance has emerged so far. Here we report the first systematic and comprehensive analytical and computational investigation for high-performance compact on-chip electro-optic modulators by considering emerging active materials, model considerations and cavity feedback at the nanoscale. We discover that the delicate interplay between the material characteristics and the optical mode properties plays a key role in defining the modulator performance. Based on physical tradeoffs between index modulation, loss, optical confinement factors and slow-light effects, we find that there exist combinations of bias, material and optical mode that yield efficient phase or amplitude modulation with acceptable insertion loss. Furthermore, we show how material properties in the epsilon near zero regime enable reduction of length by as much as by 15 times. Lastly, we introduce and apply a cavity-based electro-optic modulator figure of merit, Δλ/Δα, relating obtainable resonance tuning via phase shifting relative to the incurred losses due to the fundamental Kramers-Kronig relations suggesting optimized device operating regions with optimized modulation-to-loss tradeoffs. This work paves the way for a holistic design rule of electro-optic modulators for high-density on-chip integration.

  2. Communication: atomic force detection of single-molecule nonlinear optical vibrational spectroscopy.

    Science.gov (United States)

    Saurabh, Prasoon; Mukamel, Shaul

    2014-04-28

    Atomic Force Microscopy (AFM) allows for a highly sensitive detection of spectroscopic signals. This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime. We theoretically investigate the use of optical forces to detect time and frequency domain nonlinear optical signals. We show that, with proper phase matching, the AFM-detected signals closely resemble coherent heterodyne-detected signals. Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).

  3. Optical Spring Effect in Micro-Bubble Resonators and Its Application for the Effective Mass Measurement of Optomechanical Resonant Mode

    Directory of Open Access Journals (Sweden)

    Zhenmin Chen

    2017-09-01

    Full Text Available In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs. To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE in MBRs. This approach is demonstrated and applied to analyze the effective mass of hollow MBRs and liquid-filled MBRs, respectively. It is found that the liquid-filled MBRs has significantly stronger OSE and a less effective mass than hollow MBRs, both of the extraordinary behaviors can be beneficial for applications such as mass sensing. Larger OSE from higher order harmonics of the mechanical modes is also observed. Our work paves a way towards the developing of OSE-based high sensitive mass sensor in MBRs.

  4. Optical Spring Effect in Micro-Bubble Resonators and Its Application for the Effective Mass Measurement of Optomechanical Resonant Mode.

    Science.gov (United States)

    Chen, Zhenmin; Wu, Xiang; Liu, Liying; Xu, Lei

    2017-09-30

    In this work, we present a novel approach for obtaining the effective mass of mechanical vibration mode in micro-bubble resonators (MBRs). To be specific, the effective mass is deduced from the measurement of optical spring effect (OSE) in MBRs. This approach is demonstrated and applied to analyze the effective mass of hollow MBRs and liquid-filled MBRs, respectively. It is found that the liquid-filled MBRs has significantly stronger OSE and a less effective mass than hollow MBRs, both of the extraordinary behaviors can be beneficial for applications such as mass sensing. Larger OSE from higher order harmonics of the mechanical modes is also observed. Our work paves a way towards the developing of OSE-based high sensitive mass sensor in MBRs.

  5. Squeezing in multi-mode nonlinear optical state truncation

    International Nuclear Information System (INIS)

    Said, R.S.; Wahiddin, M.R.B.; Umarov, B.A.

    2007-01-01

    In this Letter, we show that multi-mode qubit states produced via nonlinear optical state truncation driven by classical external pumpings exhibit squeezing condition. We restrict our discussions to the two- and three-mode cases

  6. Optical cavity cooling of mechanical modes of a semiconductor nanomembrane

    DEFF Research Database (Denmark)

    Usami, Koji; Naesby, A.; Bagci, Tolga

    2012-01-01

    Mechanical oscillators can be optically cooled using a technique known as optical-cavity back-action. Cooling of composite metal–semiconductor mirrors, dielectric mirrors and dielectric membranes has been demonstrated. Here we report cavity cooling of mechanical modes in a high-quality-factor and......Mechanical oscillators can be optically cooled using a technique known as optical-cavity back-action. Cooling of composite metal–semiconductor mirrors, dielectric mirrors and dielectric membranes has been demonstrated. Here we report cavity cooling of mechanical modes in a high...

  7. An assumed mode method and finite element method investigation of the coupled vibration in a flexible-disk rotor system with lacing wires

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shui-Ting; Huang, Hong-Wu [Hunan University, Changsha (China); Chiu, Yi-Jui; Yu, Guo-Fei [Xiamen University of Technology, Xiamen (China); Yang, Chia-Hao [Taipei Chengshih University of Science and Technology, Taipei (China); Jian, Sheng-Rui [I-Shou University, Kaohsiung (China)

    2017-02-15

    The Assumed mode method (AMM) and Finite element method (FEM) were used. Their results were compared to investigate the coupled shaft-torsion, disk-transverse, and blade-bending vibrations in a flexible-disk rotor system. The blades were grouped with a spring. The flexible-disk rotor system was divided into three modes of coupled vibrations: Shaft-disk-blade, disk-blade, and blade-blade. Two new modes of coupled vibrations were introduced, namely, lacing wires-blade and lacing wires-disk-blade. The patterns of change of the natural frequencies and mode shapes of the system were discussed. The results showed the following: first, mode shapes and natural frequencies varied, and the results of the AMM and FEM differed; second, numerical calculation results showed three influencing factors on natural frequencies, namely, the lacing wire constant, the lacing wire location, and the flexible disk; lastly, the flexible disk could affect the stability of the system as reflected in the effect of the rotational speed.

  8. Higher order modes of coupled optical fibres

    International Nuclear Information System (INIS)

    Alexeyev, C N; Yavorsky, M A; Boklag, N A

    2010-01-01

    The structure of hybrid higher order modes of two coupled weakly guiding identical optical fibres is studied. On the basis of perturbation theory with degeneracy for the vector wave equation expressions for modes with azimuthal angular number l ≥ 1 are obtained that allow for the spin–orbit interaction. The spectra of polarization corrections to the scalar propagation constants are calculated in a wide range of distances between the fibres. The limiting cases of widely and closely spaced fibres are studied. The obtained results can be used for studying the tunnelling of optical vortices in directional couplers and in matters concerned with information security

  9. A Review of Hybrid Fiber-Optic Distributed Simultaneous Vibration and Temperature Sensing Technology and Its Geophysical Applications

    Directory of Open Access Journals (Sweden)

    Khalid Miah

    2017-11-01

    Full Text Available Distributed sensing systems can transform an optical fiber cable into an array of sensors, allowing users to detect and monitor multiple physical parameters such as temperature, vibration and strain with fine spatial and temporal resolution over a long distance. Fiber-optic distributed acoustic sensing (DAS and distributed temperature sensing (DTS systems have been developed for various applications with varied spatial resolution, and spectral and sensing range. Rayleigh scattering-based phase optical time domain reflectometry (OTDR for vibration and Raman/Brillouin scattering-based OTDR for temperature and strain measurements have been developed over the past two decades. The key challenge has been to find a methodology that would enable the physical parameters to be determined at any point along the sensing fiber with high sensitivity and spatial resolution, yet within acceptable frequency range for dynamic vibration, and temperature detection. There are many applications, especially in geophysical and mining engineering where simultaneous measurements of vibration and temperature are essential. In this article, recent developments of different hybrid systems for simultaneous vibration, temperature and strain measurements are analyzed based on their operation principles and performance. Then, challenges and limitations of the systems are highlighted for geophysical applications.

  10. A Review of Hybrid Fiber-Optic Distributed Simultaneous Vibration and Temperature Sensing Technology and Its Geophysical Applications.

    Science.gov (United States)

    Miah, Khalid; Potter, David K

    2017-11-01

    Distributed sensing systems can transform an optical fiber cable into an array of sensors, allowing users to detect and monitor multiple physical parameters such as temperature, vibration and strain with fine spatial and temporal resolution over a long distance. Fiber-optic distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) systems have been developed for various applications with varied spatial resolution, and spectral and sensing range. Rayleigh scattering-based phase optical time domain reflectometry (OTDR) for vibration and Raman/Brillouin scattering-based OTDR for temperature and strain measurements have been developed over the past two decades. The key challenge has been to find a methodology that would enable the physical parameters to be determined at any point along the sensing fiber with high sensitivity and spatial resolution, yet within acceptable frequency range for dynamic vibration, and temperature detection. There are many applications, especially in geophysical and mining engineering where simultaneous measurements of vibration and temperature are essential. In this article, recent developments of different hybrid systems for simultaneous vibration, temperature and strain measurements are analyzed based on their operation principles and performance. Then, challenges and limitations of the systems are highlighted for geophysical applications.

  11. Contribution to the heavy-ion optical potential from coupling to vibrational states

    Energy Technology Data Exchange (ETDEWEB)

    Donangelo, R; Canto, L F; Hussein, M S

    1978-11-01

    The component of the optical potential in the elastic channel due to the coupling to vibrational states in Coulomb excitation is derived using a previously developed semiclassical method. Several numerical examples are worked out.

  12. Circularly polarized infrared and visible sum-frequency-generation spectroscopy: Vibrational optical activity measurement

    International Nuclear Information System (INIS)

    Cheon, Sangheon; Cho, Minhaeng

    2005-01-01

    Vibrational optical activity spectroscopies utilizing either circularly polarized ir or circularly polarized visible beams were theoretically investigated by considering the infrared and visible sum-frequency-generation (IV-SFG) schemes. In addition to the purely electric dipole-allowed chiral component of the IV-SFG susceptibility, the polarizability-electric quadrupole hyperpolarizability term also contributes to the vibrationally resonant IV-SFG susceptibility. The circular-intensity-difference signal is shown to be determined by the interferences between the all-electric dipole-allowed chiral component and the polarizability-electric-dipole or electric-dipole-electric-quadrupole Raman optical activity tensor components. The circularly polarized SFG methods are shown to be potentially useful coherent spectroscopic tools for determining absolute configurations of chiral molecules in condensed phases

  13. Design of dual-mode optical fibres for the FTTH applications

    Science.gov (United States)

    Chen, Ming-Yang; Li, Yu-Rong; Zhang, Yin; Zhu, Yuan-Feng; Zhang, Yong-Kang; Zhou, Jun

    2011-01-01

    We present in this article a proposal and design for dual-mode optical fibres for fibre-to-the-home applications. High-order modes in the fibre can be effectively suppressed by the connection of the fibre with standard single-mode optical fibres at the two ends of the fibre. The alignment tolerance at the splicing process is presented. In particular, a low bending loss operation with low splice loss is demonstrated using the proposed technique.

  14. Design of dual-mode optical fibres for the FTTH applications

    International Nuclear Information System (INIS)

    Chen, Ming-Yang; Li, Yu-Rong; Zhang, Yin; Zhu, Yuan-Feng; Zhang, Yong-Kang; Zhou, Jun

    2011-01-01

    We present in this article a proposal and design for dual-mode optical fibres for fibre-to-the-home applications. High-order modes in the fibre can be effectively suppressed by the connection of the fibre with standard single-mode optical fibres at the two ends of the fibre. The alignment tolerance at the splicing process is presented. In particular, a low bending loss operation with low splice loss is demonstrated using the proposed technique

  15. Research on Effective Electric-Mechanical Coupling Coefficient of Sandwich Type Piezoelectric Ultrasonic Transducer Using Bending Vibration Mode

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2015-01-01

    Full Text Available An analytical model on electromechanical coupling coefficient and the length optimization of a bending piezoelectric ultrasonic transducer are proposed. The piezoelectric transducer consists of 8 PZT elements sandwiched between four thin electrodes, and the PZT elements are clamped by a screwed connection between fore beam and back beam. Firstly, bending vibration model of the piezoelectric transducer is built based on the Timoshenko beam theory. Secondly, the analytical model of effective electromechanical coupling coefficient is built based on the bending vibration model. Energy method and electromechanical equivalent circuit method are involved in the modelling process. To validate the analytical model, sandwich type piezoelectric transducer example in second order bending vibration mode is analysed. Effective electromechanical coupling coefficient of the transducer is optimized with simplex reflection technique, and the optimized ratio of length of the transducers is obtained. Finally, experimental prototypes of the sandwich type piezoelectric transducers are fabricated. Bending vibration mode and impedance of the experimental prototypes are tested, and electromechanical coupling coefficient is obtained according to the testing results. Results show that the analytical model is in good agreement with the experimental model.

  16. 25-Gbit/s burst-mode optical receiver using high-speed avalanche photodiode for 100-Gbit/s optical packet switching.

    Science.gov (United States)

    Nada, Masahiro; Nakamura, Makoto; Matsuzaki, Hideaki

    2014-01-13

    25-Gbit/s error-free operation of an optical receiver is successfully demonstrated against burst-mode optical input signals without preambles. The receiver, with a high-sensitivity avalanche photodiode and burst-mode transimpedance amplifier, exhibits sufficient receiver sensitivity and an extremely quick response suitable for burst-mode operation in 100-Gbit/s optical packet switching.

  17. Phonon Transport at Crystalline Si/Ge Interfaces: The Role of Interfacial Modes of Vibration

    Science.gov (United States)

    Gordiz, Kiarash; Henry, Asegun

    2016-01-01

    We studied the modal contributions to heat conduction at crystalline Si and crystalline Ge interfaces and found that more than 15% of the interface conductance arises from less than 0.1% of the modes in the structure. Using the recently developed interface conductance modal analysis (ICMA) method along with a new complimentary methodology, we mapped the correlations between modes, which revealed that a small group of interfacial modes, which exist between 12–13 THz, exhibit extremely strong correlation with other modes in the system. It is found that these interfacial modes (e.g., modes with large eigen vectors for interfacial atoms) are enabled by the degree of anharmonicity near the interface, which is higher than in the bulk, and therefore allows this small group of modes to couple to all others. The analysis sheds light on the nature of localized vibrations at interfaces and can be enlightening for other investigations of localization. PMID:26979787

  18. Far-infrared vibrational modes of DNA components studied by terahertz time-domain spectroscopy

    International Nuclear Information System (INIS)

    Fischer, B M; Walther, M; Jepsen, P Uhd

    2002-01-01

    The far-infrared dielectric function of a wide range of organic molecules is dominated by vibrations involving a substantial fraction of the atoms forming the molecule and motion associated with intermolecular hydrogen bond vibrations. Due to their collective nature such modes are highly sensitive to the intra- and intermolecular structure and thus provide a unique fingerprint of the conformational state of the molecule and effects of its environment. We demonstrate the use of terahertz time-domain spectroscopy (THz-TDS) for recording the far-infrared (0.5-4.0 THz) dielectric function of the four nucleobases and corresponding nucleosides forming the building blocks of deoxyribose nucleic acid (DNA). We observe numerous distinct spectral features with large differences between the molecules in both frequency-dependent absorption coefficient and index of refraction. Assisted by results from density-functional calculations we interpret the origin of the observed resonances as vibrations of hydrogen bonds between the molecules

  19. Pressure-dependent optical and vibrational properties of monolayer molybdenum disulfide

    KAUST Repository

    Nayak, Avinash P.; Pandey, Tribhuwan; Voiry, Damien; Liu, Jin; Moran, Samuel T.; Sharma, Ankit; Tan, Cheng; Chen, Changhsiao; Li, Lain-Jong; Chhowalla, Manish U.; Lin, Jungfu; Singh, Abhishek Kumar; Akinwande, Deji

    2015-01-01

    vibrational dynamics of the distorted monolayer 1T-MoS2 (1T′) and the monolayer 2H-MoS2 via a diamond anvil cell (DAC) and density functional theory (DFT) calculations. The direct optical band gap of the monolayer 2H-MoS2 increases by 11.7% from 1.85 to 2.08 e

  20. Anomalous vibrational modes in acetanilide: a F.D.S. incoherent inelastic neutron scattering study

    Science.gov (United States)

    Barthes, Mariette; Eckert, Juergen; Johnson, Susanna W.; Moret, Jacques; Swanson, Basil I.; Unkefer, Clifford J.

    The origin of the anomalous infra-red and Raman modes in acetanilide (C6H5NHCOCH3, or ACN)(1) , remains a subject of considerable controversy. One family of theoretical models involves Davydov-like solitons (2) nonlinear vibrational coupling (3), or "polaronic" localized modes (4)(5). An alternative interpretation of the extra-bands in terms of a Fermi resonance was proposed (6) and recently the existence of slightly non-degenerate hydrogen atom configurations (7) in the H-bond was suggested as an explanation for the anomalies.

  1. An optical channel modeling of a single mode fiber

    Science.gov (United States)

    Nabavi, Neda; Liu, Peng; Hall, Trevor James

    2018-05-01

    The evaluation of the optical channel model that accurately describes the single mode fibre as a coherent transmission medium is reviewed through analytical, numerical and experimental analysis. We used the numerical modelling of the optical transmission medium and experimental measurements to determine the polarization drift as a function of time for a fixed length of fibre. The probability distribution of the birefringence vector was derived, which is associated to the 'Poole' equation. The theory and experimental evidence that has been disclosed in the literature in the context of polarization mode dispersion - Stokes & Jones formulations and solutions for key statistics by integration of stochastic differential equations has been investigated. Besides in-depth definition of the single-mode fibre-optic channel, the modelling which concerns an ensemble of fibres each with a different instance of environmental perturbation has been analysed.

  2. Optical field-strength polarization of two-mode single-photon states

    Energy Technology Data Exchange (ETDEWEB)

    Linares, J; Nistal, M C; Barral, D; Moreno, V, E-mail: suso.linares.beiras@usc.e [Optics Area, Department of Applied Physics, Faculty of Physics and School of Optics and Optometry, University of Santiago de Compostela, Campus Universitario Sur s/n, 15782-Santiago de Compostela, Galicia (Spain)

    2010-09-15

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

  3. Optical field-strength polarization of two-mode single-photon states

    International Nuclear Information System (INIS)

    Linares, J; Nistal, M C; Barral, D; Moreno, V

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.

  4. On the magnon interaction in haematite. I - Magnon energy of optical mode.

    Science.gov (United States)

    Nagai, O.; Tanaka, T.; Bonavito, N. L.

    1972-01-01

    The effect of magnon interaction on the magnon energies of haematite was studied by the use of a recently developed random phase approximation. In this study, the spin Hamiltonian and the magnon energy were written in a power series of (1/S), where S denotes the magnitude of spin. It is known that the expression of magnon energy is rigorous up to the second term of this series. It is found that the optic mode energy is small if the free optic mode energy is small, which is contrary to Herbert's (1969) conclusion. This direct proportionality between the optic mode energy and the free optic mode energy was not confirmed in the higher order terms of 1/S.

  5. Generalized effective mode volume for leaky optical cavities

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; Van Vlack, C.; Hughes, S.

    2012-01-01

    We show explicitly how the commonly adopted prescription for calculating effective mode volumes is wrong and leads to uncontrolled errors. Instead, we introduce a generalized mode volume that can be easily evaluated based on the mode calculation methods typically applied in the literature, and wh......, and which allows one to compute the Purcell effect and other interesting optical phenomena in a rigorous and unambiguous way....

  6. Blind identification of full-field vibration modes from video measurements with phase-based video motion magnification

    Science.gov (United States)

    Yang, Yongchao; Dorn, Charles; Mancini, Tyler; Talken, Zachary; Kenyon, Garrett; Farrar, Charles; Mascareñas, David

    2017-02-01

    Experimental or operational modal analysis traditionally requires physically-attached wired or wireless sensors for vibration measurement of structures. This instrumentation can result in mass-loading on lightweight structures, and is costly and time-consuming to install and maintain on large civil structures, especially for long-term applications (e.g., structural health monitoring) that require significant maintenance for cabling (wired sensors) or periodic replacement of the energy supply (wireless sensors). Moreover, these sensors are typically placed at a limited number of discrete locations, providing low spatial sensing resolution that is hardly sufficient for modal-based damage localization, or model correlation and updating for larger-scale structures. Non-contact measurement methods such as scanning laser vibrometers provide high-resolution sensing capacity without the mass-loading effect; however, they make sequential measurements that require considerable acquisition time. As an alternative non-contact method, digital video cameras are relatively low-cost, agile, and provide high spatial resolution, simultaneous, measurements. Combined with vision based algorithms (e.g., image correlation, optical flow), video camera based measurements have been successfully used for vibration measurements and subsequent modal analysis, based on techniques such as the digital image correlation (DIC) and the point-tracking. However, they typically require speckle pattern or high-contrast markers to be placed on the surface of structures, which poses challenges when the measurement area is large or inaccessible. This work explores advanced computer vision and video processing algorithms to develop a novel video measurement and vision-based operational (output-only) modal analysis method that alleviate the need of structural surface preparation associated with existing vision-based methods and can be implemented in a relatively efficient and autonomous manner with little

  7. Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

    2009-05-07

    Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

  8. Vibration Monitoring Using Fiber Optic Sensors in a Lead-Bismuth Eutectic Cooled Nuclear Fuel Assembly

    Directory of Open Access Journals (Sweden)

    Ben De Pauw

    2016-04-01

    Full Text Available Excessive fuel assembly vibrations in nuclear reactor cores should be avoided in order not to compromise the lifetime of the assembly and in order to prevent the occurrence of safety hazards. This issue is particularly relevant to new reactor designs that use liquid metal coolants, such as, for example, a molten lead-bismuth eutectic. The flow of molten heavy metal around and through the fuel assembly may cause the latter to vibrate and hence suffer degradation as a result of, for example, fretting wear or mechanical fatigue. In this paper, we demonstrate the use of optical fiber sensors to measure the fuel assembly vibration in a lead-bismuth eutectic cooled installation which can be used as input to assess vibration-related safety hazards. We show that the vibration characteristics of the fuel pins in the fuel assembly can be experimentally determined with minimal intrusiveness and with high precision owing to the small dimensions and properties of the sensors. In particular, we were able to record local strain level differences of about 0.2 μϵ allowing us to reliably estimate the vibration amplitudes and modal parameters of the fuel assembly based on optical fiber sensor readings during different stages of the operation of the facility, including the onset of the coolant circulation and steady-state operation.

  9. Whispering gallery mode selection in optical bottle microresonators

    Science.gov (United States)

    Ding, Ming; Senthil Murugan, Ganapathy; Brambilla, Gilberto; Zervas, Michalis N.

    2012-02-01

    We demonstrated a method to excite selected whispering gallery modes in optical bottle microresonators (BMR) by inscribing microgroove scars on their surface by focused ion beam milling. Substantial spectral clean-up is obtained in appropriately scarred BMRs, providing the potential for high performance sensors and other optical devices.

  10. Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

    2017-06-01

    In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

  11. Resonant and kinematical enhancement of He scattering from LiF(001) surface and pseudosurface vibrational normal modes

    International Nuclear Information System (INIS)

    Nichols, W.L.; Weare, J.H.

    1986-01-01

    One-phonon cross sections calculated from sagittally polarized vibrational normal modes account for most salient inelastic-scattering intensities seen in He-LiF(001) and measurements published by Brusdeylins, Doak, and Toennies. We have found that most inelastic intensities which cannot be attributed to potential resonances can be explained as kinematically enhanced scattering from both surface and pseudosurface bulk modes

  12. Optical vortex propagation in few-mode rectangular polymer waveguides

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir S.; Chipouline, Arkadi; Zywietz, Urs

    2017-01-01

    We demonstrate that rectangular few-mode dielectric waveguides, fabricated with standard lithographic technique, can support on-chip propagation of optical vortices. We show that specific superpositions of waveguide eigenmodes form quasi-degenerate modes carrying light with high purity states...

  13. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-01-01

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed

  14. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Hiroaki; Sul, Soohwan [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States); Ge, Nien-Hui, E-mail: nhge@uci.edu [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States)

    2013-08-30

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  15. Low-Threshold Optical Parametric Oscillations in a Whispering Gallery Mode Resonator

    DEFF Research Database (Denmark)

    Fürst, J. U.; Strekalov, D. V.; Elser, D.

    2010-01-01

    In whispering gallery mode (WGM) resonator light is guided by continuous total internal reflection along a curved surface. Fabricating such resonators from an optically nonlinear material one takes advantage of their exceptionally high quality factors and small mode volumes to achieve extremely...... efficient optical frequency conversion. Our analysis of the phase-matching conditions for optical parametric down-conversion (PDC) in a spherical WGM resonator shows their direct relation to the sum rules for photons' angular momenta and predicts a very low parametric oscillation threshold. We realized...... such an optical parametric oscillator (OPO) based on naturally phase-matched PDC in lithium niobate. We demonstrated a single-mode, strongly nondegenerate OPO with a threshold of 6.7  μW and linewidth under 10 MHz. This work demonstrates the remarkable capabilities of WGM-based OPOs....

  16. Vibrational normal modes of diazo-dimedone: A comparative study by Fourier infrared/Raman spectroscopies and conformational analysis by MM/QM

    Science.gov (United States)

    Téllez Soto, C. A.; Ramos, J. M.; Rianelli, R. S.; de Souza, M. C. B. V.; Ferreira, V. F.

    2007-07-01

    The 2-diazo-5,5-dimethyl-cyclohexane-1,3-dione ( 3) was synthesized and the FT-IR/Raman spectra were measured with the purpose of obtain a full assignment of the vibrational modes. Singular aspects concerning the -C dbnd N dbnd N oscillator are discussed in view of two strong bands observed in the region of 2300-2100 cm -1 in both, Infrared and Raman spectra. The density functional theory (DFT) was used to obtain the geometrical structure and for assisting in the vibrational assignment joint to the traditional normal coordinate analysis (NCA). The observed wavenumbers at 2145 (IR), 2144(R) are assigned as the coupled ν(N dbnd N) + ν(C dbnd N) vibrational mode with higher participation of the N dbnd N stretching. A 2188 cm -1 (IR) and at 2186 cm -1 (R) can be assigned as a overtone of one of ν(CC) normal mode or to a combination band of the fundamentals δ(CCH) found at 1169 cm -1 and the δ (CC dbnd N) found at 1017 cm -1 enhanced by Fermi resonance.

  17. Bio-inspired multi-mode optic flow sensors for micro air vehicles

    Science.gov (United States)

    Park, Seokjun; Choi, Jaehyuk; Cho, Jihyun; Yoon, Euisik

    2013-06-01

    Monitoring wide-field surrounding information is essential for vision-based autonomous navigation in micro-air-vehicles (MAV). Our image-cube (iCube) module, which consists of multiple sensors that are facing different angles in 3-D space, can be applied to the wide-field of view optic flows estimation (μ-Compound eyes) and to attitude control (μ- Ocelli) in the Micro Autonomous Systems and Technology (MAST) platforms. In this paper, we report an analog/digital (A/D) mixed-mode optic-flow sensor, which generates both optic flows and normal images in different modes for μ- Compound eyes and μ-Ocelli applications. The sensor employs a time-stamp based optic flow algorithm which is modified from the conventional EMD (Elementary Motion Detector) algorithm to give an optimum partitioning of hardware blocks in analog and digital domains as well as adequate allocation of pixel-level, column-parallel, and chip-level signal processing. Temporal filtering, which may require huge hardware resources if implemented in digital domain, is remained in a pixel-level analog processing unit. The rest of the blocks, including feature detection and timestamp latching, are implemented using digital circuits in a column-parallel processing unit. Finally, time-stamp information is decoded into velocity from look-up tables, multiplications, and simple subtraction circuits in a chip-level processing unit, thus significantly reducing core digital processing power consumption. In the normal image mode, the sensor generates 8-b digital images using single slope ADCs in the column unit. In the optic flow mode, the sensor estimates 8-b 1-D optic flows from the integrated mixed-mode algorithm core and 2-D optic flows with an external timestamp processing, respectively.

  18. Vibrational spectroscopic and non-linear optical activity studies on nicotinanilide : A DFT approach

    Science.gov (United States)

    Premkumar, S.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-06-01

    The molecular structure of nicotinanilide was optimized by the DFT/B3LYP method with cc-pVTZ basis set using Gaussian 09 program. The first order hyperpolarizability of the molecule was calculated, which exhibits the higher nonlinear optical activity. The natural bond orbital analysis confirms the presence of intramolecular charge transfer and the hydrogen bonding interaction, which leads to the higher nonlinear optical activity of the molecule. The Frontier molecular orbitals analysis of the molecule shows that the delocalization of electron density occurs within the molecule. The lower energy gap indicates that the hydrogen bond formation between the charged species. The vibrational frequencies were calculated and assigned on the basis of potential energy distribution calculation using the VEDA 4.0 program and the corresponding vibrational spectra were simulated. Hence, the nicotinanilide molecule can be a good candidate for second-order NLO material.

  19. Dual-Mode Operation of an Optical Lattice Clock Using Strontium and Ytterbium Atoms.

    Science.gov (United States)

    Akamatsu, Daisuke; Kobayashi, Takumi; Hisai, Yusuke; Tanabe, Takehiko; Hosaka, Kazumoto; Yasuda, Masami; Hong, Feng-Lei

    2018-06-01

    We have developed an optical lattice clock that can operate in dual modes: a strontium (Sr) clock mode and an ytterbium (Yb) clock mode. Dual-mode operation of the Sr-Yb optical lattice clock is achieved by alternately cooling and trapping 87 Sr and 171 Yb atoms inside the vacuum chamber of the clock. Optical lattices for Sr and Yb atoms were arranged with horizontal and vertical configurations, respectively, resulting in a small distance of the order of between the trapped Sr and Yb atoms. The 1 S 0 - 3 P 0 clock transitions in the trapped atoms were interrogated in turn and the clock lasers were stabilized to the transitions. We demonstrated the frequency ratio measurement of the Sr and Yb clock transitions by using the dual-mode operation of the Sr-Yb optical lattice clock. The dual-mode operation can reduce the uncertainty of the blackbody radiation shift in the frequency ratio measurement, because both Sr and Yb atoms share the same blackbody radiation.

  20. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Science.gov (United States)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-08-01

    We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester Cdbnd O and diazo Ndbnd N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency-frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single Cdbnd O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  1. Application of empirical mode decomposition method for characterization of random vibration signals

    Directory of Open Access Journals (Sweden)

    Setyamartana Parman

    2016-07-01

    Full Text Available Characterization of finite measured signals is a great of importance in dynamical modeling and system identification. This paper addresses an approach for characterization of measured random vibration signals where the approach rests on a method called empirical mode decomposition (EMD. The applicability of proposed approach is tested in one numerical and experimental data from a structural system, namely spar platform. The results are three main signal components, comprising: noise embedded in the measured signal as the first component, first intrinsic mode function (IMF called as the wave frequency response (WFR as the second component and second IMF called as the low frequency response (LFR as the third component while the residue is the trend. Band-pass filter (BPF method is taken as benchmark for the results obtained from EMD method.

  2. Measurement of correlations between low-frequency vibrational modes and particle rearrangements in quasi-two-dimensional colloidal glasses

    NARCIS (Netherlands)

    Chen, K.; Manning, M.L.; Yunker, P.J.; Ellenbroek, W.G.; Zhang, Zexin; Liu, Andrea J.; Yodh, A.G.

    2011-01-01

    We investigate correlations between low-frequency vibrational modes and rearrangements in two-dimensional colloidal glasses composed of thermosensitive microgel particles, which readily permit variation of the sample packing fraction. At each packing fraction, the particle displacement covariance

  3. Experimental Study of Flexible Plate Vibration Control by Using Two-Loop Sliding Mode Control Strategy

    Science.gov (United States)

    Yang, Jingyu; Lin, Jiahui; Liu, Yuejun; Yang, Kang; Zhou, Lanwei; Chen, Guoping

    2017-08-01

    It is well known that intelligent control theory has been used in many research fields, novel modeling method (DROMM) is used for flexible rectangular active vibration control, and then the validity of new model is confirmed by comparing finite element model with new model. In this paper, taking advantage of the dynamics of flexible rectangular plate, a two-loop sliding mode (TSM) MIMO approach is introduced for designing multiple-input multiple-output continuous vibration control system, which can overcome uncertainties, disturbances or unstable dynamics. An illustrative example is given in order to show the feasibility of the method. Numerical simulations and experiment confirm the effectiveness of the proposed TSM MIMO controller.

  4. Short pulse generation from a passively mode-locked fiber optical parametric oscillator with optical time-stretch.

    Science.gov (United States)

    Qiu, Yi; Wei, Xiaoming; Du, Shuxin; Wong, Kenneth K Y; Tsia, Kevin K; Xu, Yiqing

    2018-04-16

    We propose a passively mode-locked fiber optical parametric oscillator assisted with optical time-stretch. Thanks to the lately developed optical time-stretch technique, the onset oscillating spectral components can be temporally dispersed across the pump envelope and further compete for the parametric gain with the other parts of onset oscillating sidebands within the pump envelope. By matching the amount of dispersion in optical time-stretch with the pulse width of the quasi-CW pump and oscillating one of the parametric sidebands inside the fiber cavity, we numerically show that the fiber parametric oscillator can be operated in a single pulse regime. By varying the amount of the intracavity dispersion, we further verify that the origin of this single pulse mode-locking regime is due to the optical pulse stretching and compression.

  5. Silicon Micromachined Sensor for Broadband Vibration Analysis

    Science.gov (United States)

    Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

    1995-01-01

    The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

  6. Confinement of vibrational modes within crystalline lattices using thin amorphous layers

    International Nuclear Information System (INIS)

    Bagolini, Luigi; Mattoni, Alessandro; Lusk, Mark T

    2017-01-01

    It is possible to confine vibrational modes to a crystal by encapsulating it within thin disordered layers with the same average properties as the crystal. This is not due to an impedance mismatch between materials but, rather, to higher order moments in the distribution of density and stiffness in the disordered phase—i.e. it is a result of material substructure. The concept is elucidated in an idealized one-dimensional setting and then demonstrated for a realistic nanocrystalline geometry. This offers the prospect of specifically engineering higher order property distributions as an alternate means of managing phonons. (paper)

  7. Two-photon optics of Bessel-Gaussian modes

    CSIR Research Space (South Africa)

    McLaren, M

    2013-09-01

    Full Text Available In this paper we consider geometrical two-photon optics of Bessel-Gaussian modes generated in spontaneous parametric down-conversion of a Gaussian pump beam. We provide a general theoretical expression for the orbital angular momentum (OAM) spectrum...

  8. Vibration modes of 3n-gaskets and other fractals

    Energy Technology Data Exchange (ETDEWEB)

    Bajorin, N; Chen, T; Dagan, A; Emmons, C; Hussein, M; Khalil, M; Mody, P; Steinhurst, B; Teplyaev, A [Department of Mathematics, University of Connecticut, Storrs CT 06269 (United States)

    2008-01-11

    We rigorously study eigenvalues and eigenfunctions (vibration modes) on the class of self-similar symmetric finitely ramified fractals, which include the Sierpinski gasket and other 3n-gaskets. We consider the classical Laplacian on fractals which generalizes the usual one-dimensional second derivative, is the generator of the self-similar diffusion process, and has possible applications as the quantum Hamiltonian. We develop a theoretical matrix analysis, including analysis of singularities, which allows us to compute eigenvalues, eigenfunctions and their multiplicities exactly. We support our theoretical analysis by symbolic and numerical computations. Our analysis, in particular, allows the computation of the spectral zeta function on fractals and the limiting distribution of eigenvalues (i.e., integrated density of states). We consider such examples as the level-3 Sierpinski gasket, a fractal 3-tree, and the diamond fractal.

  9. Direct assignment of molecular vibrations via normal mode analysis of the neutron dynamic pair distribution function technique

    International Nuclear Information System (INIS)

    Fry-Petit, A. M.; Sheckelton, J. P.; McQueen, T. M.; Rebola, A. F.; Fennie, C. J.; Mourigal, M.; Valentine, M.; Drichko, N.

    2015-01-01

    For over a century, vibrational spectroscopy has enhanced the study of materials. Yet, assignment of particular molecular motions to vibrational excitations has relied on indirect methods. Here, we demonstrate that applying group theoretical methods to the dynamic pair distribution function analysis of neutron scattering data provides direct access to the individual atomic displacements responsible for these excitations. Applied to the molecule-based frustrated magnet with a potential magnetic valence-bond state, LiZn 2 Mo 3 O 8 , this approach allows direct assignment of the constrained rotational mode of Mo 3 O 13 clusters and internal modes of MoO 6 polyhedra. We anticipate that coupling this well known data analysis technique with dynamic pair distribution function analysis will have broad application in connecting structural dynamics to physical properties in a wide range of molecular and solid state systems

  10. Nonlinear network model analysis of vibrational energy transfer and localisation in the Fenna-Matthews-Olson complex

    Science.gov (United States)

    Morgan, Sarah E.; Cole, Daniel J.; Chin, Alex W.

    2016-11-01

    Collective protein modes are expected to be important for facilitating energy transfer in the Fenna-Matthews-Olson (FMO) complex of photosynthetic green sulphur bacteria, however to date little work has focussed on the microscopic details of these vibrations. The nonlinear network model (NNM) provides a computationally inexpensive approach to studying vibrational modes at the microscopic level in large protein structures, whilst incorporating anharmonicity in the inter-residue interactions which can influence protein dynamics. We apply the NNM to the entire trimeric FMO complex and find evidence for the existence of nonlinear discrete breather modes. These modes tend to transfer energy to the highly connected core pigments, potentially opening up alternative excitation energy transfer routes through their influence on pigment properties. Incorporating localised modes based on these discrete breathers in the optical spectra calculations for FMO using ab initio site energies and excitonic couplings can substantially improve their agreement with experimental results.

  11. MEMS acceleration sensor with remote optical readout for continuous power generator monitoring

    Directory of Open Access Journals (Sweden)

    Tormen Maurizio

    2015-01-01

    Full Text Available Miniaturized accelerometers with remote optical readout are required devices for the continuous monitoring of vibrations inside power generators. In turbo and hydro generators, end-winding vibrations are present during operation causing in the long term undesirable out-of-service repairs. Continuous monitoring of these vibrations is therefore mandatory. The high electromagnetic fields in the generators impose the use of devices immune to electromagnetic interferences. In this paper a MEMS based accelerometer with remote optical readout is presented. Advantages of the proposed device are the use of a differential optical signal to reject the common mode signal and noise, the reduced number of steps for the MEMS chip fabrication and for the system assembly, and the reduced package volume.

  12. Quasi-optical millimeter wave rotating TE62 mode generator

    International Nuclear Information System (INIS)

    Li Shaopu; Zhang Conghui; Wang Zhong; Guo Feng; Chen Hongbin; Hu Linlin; Pan Wenwu

    2011-01-01

    The design,measurement technique and experimental results of rotating TE 6 2 mode generator are presented. The source includes millimeter wave optical system and open coaxial wave guide system. The millimeter wave optical system consists of pyramid antenna, hyperbolical reflector, parabolic reflector and quasi parabolic reflector. The open coaxial wave guide system contains open coaxial wave guide cavity, cylinder wave guide and output antenna. It is tested by network analyser and millimeter wave near field pattern auto-test system, and the purity of rotating TE 6 2 mode at 96.4 GHz is about 97%. (authors)

  13. Propagation of an optical discharge through optical fibres upon interference of modes

    International Nuclear Information System (INIS)

    Bufetov, I A; Frolov, A A; Shubin, A V; Likhachev, M E; Lavrishchev, S V; Dianov, E M

    2008-01-01

    The propagation of an optical discharge (OD) through optical fibres upon interference of LP 01 and LP 02 modes is studied. Under these conditions after the OD propagation through the fibre, the formation of an axially-symmetric group sequence of voids with a spatial period equal to that of mode interference (200-500 μm depending on the parameters of the fibre) is observed. The groups of voids are formed near the sections of the fibre with a minimal diameter of the intensity distribution of laser radiation. Large spaces between voids in the fibre have allowed us to measure accurately the difference Δn of refractive indices of the fibre core and cladding and distribution of dopants in different cross sections of the fibre after the OD propagation. A substantial increase in Δn (up to ten times) is observed. Approximately half this increase is caused by compression and densification of the fibre material after the propagation of the optical discharge. (interaction of laser radiation with matter. laser plasma)

  14. Active composite waveguides with a suppressed competition of optical modes

    International Nuclear Information System (INIS)

    Vysotskii, D V; Elkin, N N; Napartovich, A P

    2008-01-01

    The possibilities of separating the fundamental optical mode in composite waveguides by selecting the structure of amplifying regions are analysed. Conditions are presented under which the fundamental mode preserves the highest gain at any saturation. (letters)

  15. Enhancement of oscillation characteristics of a gyrotron by a built-in quasi-optical mode converter

    International Nuclear Information System (INIS)

    Hayashi, Kenichi; Mitsunaka, Yoshika; Komuro, Mitsuo

    1994-01-01

    Oscillation characteristics are analyzed experimentally and numerically by using two gyrotrons with a power level of 500 kW, a conventional tube and a tube with a built-in quasi-optical mode converter. Both tubes have a 120 GHz, TE 12,2 cavity of the same geometry and a single disk alumina window. The quasi-optical mode converter consists of an α-cut launcher and five mirrors. In the conventional tube, reflection of the competing mode at the output window prevents the main mode from oscillating stably in the operation region predicted by the design. Mode selectivity of the quasi-optical mode converter removes the influence of the reflection on the oscillation. Consequently, the experimental results in the tube with the quasi-optical mode converter are in good agreement with the design values. (author)

  16. Quasi-optical mode converter for a coaxial cavity gyrotron

    International Nuclear Information System (INIS)

    Jin, J.

    2007-03-01

    This work concentrates on the synthesis of the quasioptical mode converter for the 170 GHz, TE 34,19 -mode, 2MW, CW coaxial-cavity gyrotron at Forschungszentrum Karlsruhe (FZK). The improvement of the general method for the design of so-call dimpled-wall launcher to provide a good Gaussian mode content is described. This method is verified through the design of a launcher operating in the TE 22,6 mode at 118 GHz. A phase rule is proposed as a quality criterion for monitoring the optimization and the choices of parameters of the quasi-optical mode converter. High-order harmonics introduced to the launcher wall deformations are proposed for this gyrotron. The launcher is numerically optimized, the fields on the cut edges are suppressed. The fields in the launcher are well approximated by the waveguide modes, the radiated fields are calculated using the scalar diffraction integral. The procedure for the numerical optimization of the mirror system is improved, the tolerance conditions of the phase correcting mirrors are investigated. A conversion efficiency of 95.8% to the circular fundamental Gaussian distribution with 20mm beam waist and power transmission of 90% are achieved in the window plane using the optimized quasi-optical mode converter. The methods to ameliorate the initial conditions of the phase correcting mirrors are explored. (orig.)

  17. Linking structure and vibrational mode coupling using high-resolution infrared spectroscopy: A comparison of gauche and trans 1-chloro-2-fluoroethane

    Science.gov (United States)

    Miller, C. Cameron; Stone, Stephen C.; Philips, Laura A.

    1995-01-01

    The high-resolution infrared spectrum of 1-chloro-2-fluoroethane in a molecular beam was collected over the 2975-2994 cm-1 spectral region. The spectral region of 2975-2981 cm-1 contains a symmetric C-H stretching vibrational band of the gauche conformer containing the 35Cl isotope. The spectral region of 2985-2994 cm-1 contains three vibrational bands of the trans conformer. Two of the three bands are assigned as an antisymmetric C-H stretch of each of the two different chlorine isotopes. The third band is assigned as a symmetric C-H stretch of the 35Cl isotope. The gauche conformer of 1-chloro-2-fluoroethane showed doublet patterns similar to those previously observed in 1,2-difluoroethane. The model for 1,2-difluoroethane is further refined in the present work. These refinements suggest that the coupling dark state in 1,2-difluoroethane is composed of 1 quantum C-H bend, 1 quantum C-C stretch, and 12 quanta of torsion. For 1-chloro-2-fluoroethane the dark state could not be identified due to a small data set. The trans conformer of 1-chloro-2-fluoroethane showed no evidence of mode coupling in the three vibrational bands. Including 2-fluoroethanol in this series of molecules, the extent of vibrational mode coupling did not correlate with the density of states available for coupling. Therefore, density of states alone is insufficient to explain the observed trend. A correlation was observed between the degree of intramolecular interaction and vibrational mode coupling.

  18. Frequency Response of the Sample Vibration Mode in Scanning Probe Acoustic Microscope

    International Nuclear Information System (INIS)

    Ya-Jun, Zhao; Qian, Cheng; Meng-Lu, Qian

    2010-01-01

    Based on the interaction mechanism between tip and sample in the contact mode of a scanning probe acoustic microscope (SPAM), an active mass of the sample is introduced in the mass-spring model. The tip motion and frequency response of the sample vibration mode in the SPAM are calculated by the Lagrange equation with dissipation function. For the silicon tip and glass assemblage in the SPAM the frequency response is simulated and it is in agreement with the experimental result. The living myoblast cells on the glass slide are imaged at resonance frequencies of the SPAM system, which are 20kHz, 30kHz and 120kHz. It is shown that good contrast of SPAM images could be obtained when the system is operated at the resonance frequencies of the system in high and low-frequency regions

  19. A pragmatic approach to including complex natural modes of vibration in aeroelastic analysis

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2015-09-01

    Full Text Available complex natural modes of vibration in aeroelastic analysis Louw van Zyl International Aerospace Symposium of South Africa 14 to 16 September, 2015 Stellenbosch, South Africa Slide 2 © CSIR 2006 www.csir.co.za Problem statement..., the square of the angular frequencies in radians per second) [ ]{ } [ ]{ } [ ]{ } { }fxKxCxM =++ &&& [ ]{ } [ ]{ } 0=+ xKxMs2 Slide 4 © CSIR 2006 www.csir.co.za Structural Dynamics (continued) • The corresponding eigenvectors are real...

  20. Recirculating beam-breakup thresholds for polarized higher-order modes with optical coupling

    Directory of Open Access Journals (Sweden)

    Georg H. Hoffstaetter

    2007-04-01

    Full Text Available Here we will derive the general theory of the beam-breakup (BBU instability in recirculating linear accelerators with coupled beam optics and with polarized higher-order dipole modes. The bunches do not have to be at the same radio-frequency phase during each recirculation turn. This is important for the description of energy recovery linacs (ERLs where beam currents become very large and coupled optics are used on purpose to increase the threshold current. This theory can be used for the analysis of phase errors of recirculated bunches, and of errors in the optical coupling arrangement. It is shown how the threshold current for a given linac can be computed and a remarkable agreement with tracking data is demonstrated. General formulas are then analyzed for several analytically solvable problems: (a Why can different higher order modes (HOM in one cavity couple and why can they then not be considered individually, even when their frequencies are separated by much more than the resonance widths of the HOMs? For the Cornell ERL as an example, it is noted that optimum advantage is taken of coupled optics when the cavities are designed with an x-y HOM frequency splitting of above 50 MHz. The simulated threshold current is then far above the design current of this accelerator. To justify that the simulation can represent an actual accelerator, we simulate cavities with 1 to 8 modes and show that using a limited number of modes is reasonable. (b How does the x-y coupling in the particle optics determine when modes can be considered separately? (c How much of an increase in threshold current can be obtained by coupled optics and why does the threshold current for polarized modes diminish roughly with the square root of the HOMs’ quality factors. Because of this square root scaling, polarized modes with coupled optics increase the threshold current more effectively for cavities that have rather large HOM quality factors, e.g. those without very

  1. Diffractive optical elements for transformation of modes in lasers

    Science.gov (United States)

    Sridharan, Arun K.; Pax, Paul H.; Heebner, John E.; Drachenberg, Derrek R.; Armstrong, James P.; Dawson, Jay W.

    2015-09-01

    Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

  2. Mode division multiplexing technology for single-fiber optical trapping axial-position adjustment.

    Science.gov (United States)

    Liu, Zhihai; Wang, Lei; Liang, Peibo; Zhang, Yu; Yang, Jun; Yuan, Libo

    2013-07-15

    We demonstrate trapped yeast cell axial-position adjustment without moving the optical fiber in a single-fiber optical trapping system. The dynamic axial-position adjustment is realized by controlling the power ratio of the fundamental mode beam (LP01) and the low-order mode beam (LP11) generated in a normal single-core fiber. In order to separate the trapping positions produced by the two mode beams, we fabricate a special fiber tapered tip with a selective two-step method. A yeast cell of 6 μm diameter is moved along the optical axis direction for a distance of ~3 μm. To the best of our knowledge, this is the first demonstration of the trapping position adjustment without moving the fiber for single-fiber optical tweezers. The excitation and utilization of multimode beams in a single fiber constitutes a new development for single-fiber optical trapping and makes possible more practical applications in biomedical research fields.

  3. Observation of the low frequency vibrational modes of bacteriophage M13 in water by Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Tsen Shaw-Wei D

    2006-09-01

    Full Text Available Abstract Background Recently, a technique which departs radically from conventional approaches has been proposed. This novel technique utilizes biological objects such as viruses as nano-templates for the fabrication of nanostructure elements. For example, rod-shaped viruses such as the M13 phage and tobacco mosaic virus have been successfully used as biological templates for the synthesis of semiconductor and metallic nanowires. Results and discussion Low wave number (≤ 20 cm-1 acoustic vibrations of the M13 phage have been studied using Raman spectroscopy. The experimental results are compared with theoretical calculations based on an elastic continuum model and appropriate Raman selection rules derived from a bond polarizability model. The observed Raman mode has been shown to belong to one of the Raman-active axial torsion modes of the M13 phage protein coat. Conclusion It is expected that the detection and characterization of this low frequency vibrational mode can be used for applications in nanotechnology such as for monitoring the process of virus functionalization and self-assembly. For example, the differences in Raman spectra can be used to monitor the coating of virus with some other materials and nano-assembly process, such as attaching a carbon nanotube or quantum dots.

  4. Theory of the normal modes of vibrations in the lanthanide type crystals

    Science.gov (United States)

    Acevedo, Roberto; Soto-Bubert, Andres

    2008-11-01

    For the lanthanide type crystals, a vast and rich, though incomplete amount of experimental data has been accumulated, from linear and non linear optics, during the last decades. The main goal of the current research work is to report a new methodology and strategy to put forward a more representative approach to account for the normal modes of vibrations for a complex N-body system. For illustrative purposes, the chloride lanthanide type crystals Cs2NaLnCl6 have been chosen and we develop new convergence tests as well as a criterion to deal with the details of the F-matrix (potential energy matrix). A novel and useful concept of natural potential energy distributions (NPED) is introduced and examined throughout the course of this work. The diagonal and non diagonal contributions to these NPED-values, are evaluated for a series of these crystals explicitly. Our model is based upon a total of seventy two internal coordinates and ninety eight internal Hooke type force constants. An optimization mathematical procedure is applied with reference to the series of chloride lanthanide crystals and it is shown that the strategy and model adopted is sound from both a chemical and a physical viewpoints. We can argue that the current model is able to accommodate a number of interactions and to provide us with a very useful physical insight. The limitations and advantages of the current model and the most likely sources for improvements are discussed in detail.

  5. Intrusion recognition for optic fiber vibration sensor based on the selective attention mechanism

    Science.gov (United States)

    Xu, Haiyan; Xie, Yingjuan; Li, Min; Zhang, Zhuo; Zhang, Xuewu

    2017-11-01

    Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. A fiber optic perimeter detection system based on all-fiber interferometric sensor is proposed, through the back-end analysis, processing and intelligent identification, which can distinguish effects of different intrusion activities. In this paper, an intrusion recognition based on the auditory selective attention mechanism is proposed. Firstly, considering the time-frequency of vibration, the spectrogram is calculated. Secondly, imitating the selective attention mechanism, the color, direction and brightness map of the spectrogram is computed. Based on these maps, the feature matrix is formed after normalization. The system could recognize the intrusion activities occurred along the perimeter sensors. Experiment results show that the proposed method for the perimeter is able to differentiate intrusion signals from ambient noises. What's more, the recognition rate of the system is improved while deduced the false alarm rate, the approach is proved by large practical experiment and project.

  6. High resolution spectroscopy of 1,2-difluoroethane in a molecular beam: A case study of vibrational mode-coupling

    Science.gov (United States)

    Mork, Steven W.; Miller, C. Cameron; Philips, Laura A.

    1992-09-01

    The high resolution infrared spectrum of 1,2-difluoroethane (DFE) in a molecular beam has been obtained over the 2978-2996 cm-1 spectral region. This region corresponds to the symmetric combination of asymmetric C-H stretches in DFE. Observed rotational fine structure indicates that this C-H stretch is undergoing vibrational mode coupling to a single dark mode. The dark mode is split by approximately 19 cm-1 due to tunneling between the two identical gauche conformers. The mechanism of the coupling is largely anharmonic with a minor component of B/C plane Coriolis coupling. Effects of centrifugal distortion along the molecular A-axis are also observed. Analysis of the fine structure identifies the dark state as being composed of C-C torsion, CCF bend, and CH2 rock. Coupling between the C-H stretches and the C-C torsion is of particular interest because DFE has been observed to undergo vibrationally induced isomerization from the gauche to trans conformer upon excitation of the C-H stretch.

  7. Mode-Locked Semiconductor Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten; Larsson, David; Oxenløwe, Leif Katsuo

    2005-01-01

    We present investigations on 10 and 40 GHz monolithic mode-locked lasers for applications in optical communications systems. New all-active lasers with one to three quantum wells have been designed, fabricated and characterized....

  8. Optical self-injection mode-locking of semiconductor optical amplifier fiber ring with electro-absorption modulation—fundamentals and applications

    International Nuclear Information System (INIS)

    Chi, Yu-Chieh; Lin, Gong-Ru

    2013-01-01

    The optical self-injection mode-locking of a semiconductor optical amplifier incorporated fiber ring laser (SOAFL) with spectrally sliced multi-channel carriers is demonstrated for applications. The synthesizer-free SOAFL pulse-train is delivered by optical injection mode-locking with a 10 GHz self-pulsed electro-absorption modulator (EAM). Such a coupled optical and electronic resonator architecture facilitates a self-feedback oscillation with a higher Q-factor and lower phase/intensity noises when compared with conventional approaches. The theoretical model of such an injection-mode-locking SOAFL is derived to improve the self-pulsating performance of the optical return-to-zero (RZ) carrier, thus providing optimized pulsewidth, pulse extinction ratio, effective Q-factor, frequency variation and timing jitter of 11.4 ps, 9.1 dB, 4 × 10 5 , −1 bi-directional WDM transmission network with down-stream RZ binary phase-shift keying (RZ-BPSK) and up-stream re-modulated RZ on–off-keying (RZ-OOK) formats. Under BPSK/OOK bi-directional data transmission, the self-pulsed harmonic mode-locking SOAFL simultaneously provides four to six WDM channels for down-stream RZ-BPSK and up-stream RZ-OOK formats with receiving sensitivities of −17 and −15.2 dBm at a bit error rate of 10 −9 , respectively. (paper)

  9. Interference-free optical detection for Raman spectroscopy

    Science.gov (United States)

    Fischer, David G (Inventor); Kojima, Jun (Inventor); Nguyen, Quang-Viet (Inventor)

    2012-01-01

    An architecture for spontaneous Raman scattering (SRS) that utilizes a frame-transfer charge-coupled device (CCD) sensor operating in a subframe burst gating mode to realize time-resolved combustion diagnostics is disclosed. The technique permits all-electronic optical gating with microsecond shutter speeds (<5 .mu.s), without compromising optical throughput or image fidelity. When used in conjunction with a pair of orthogonally-polarized excitation lasers, the technique measures time-resolved vibrational Raman scattering that is minimally contaminated by problematic optical background noise.

  10. Optical Communications With A Geiger Mode APD Array

    Science.gov (United States)

    2016-02-09

    practical performance of a Geiger mode avalanche photodiode ( GM -APD, or Geiger mode APD) array for use in optical com- munications systems. I designed and...signal quality in the first half of the frame. These shorter reset times also did not offer any advantage in the maximum number of counts able to be...pattern was advantageous for the modifications being made in post-processing on the benchmark data. In particular, this allowed post-processing results

  11. Studies of interstellar vibrationally-excited molecules

    International Nuclear Information System (INIS)

    Ziurys, L.M.; Snell, R.L.; Erickson, N.R.

    1986-01-01

    Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H 2 , SiO, HC 3 N, and CH 3 CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam

  12. Two-Photon Vibrational Spectroscopy using local optical fields of gold and silver nanostructures

    Science.gov (United States)

    Kneipp, Katrin; Kneipp, Janina; Kneipp, Harald

    2007-03-01

    Spectroscopic effects can be strongly affected when they take place in the immediate vicinity of metal nanostructures due to coupling to surface plasmons. We introduce a new approach that suggests highly efficient two-photon labels as well as two-photon vibrational spectroscopy for non-destructive chemical probing. The underlying spectroscopic effect is the incoherent inelastic scattering of two photons on the vibrational quantum states performed in the enhanced local optical fields of gold nanoparticles, surface enhanced hyper Raman scattering (SEHRS). We infer effective two-photon cross sections for SEHRS on the order of 10^5 GM, similar or higher than the best known cross sections for two-photon fluorescence. SEHRS combines the advantages of two-photon spectroscopy with the structural information of vibrational spectroscopy, and the high sensitivity and nanometer-scale local confinement of plasmonics-based spectroscopy.

  13. Distributed optical fiber vibration sensing using phase-generated carrier demodulation algorithm

    Science.gov (United States)

    Yu, Zhihua; Zhang, Qi; Zhang, Mingyu; Dai, Haolong; Zhang, Jingjing; Liu, Li; Zhang, Lijun; Jin, Xing; Wang, Gaifang; Qi, Guang

    2018-05-01

    A novel optical fiber-distributed vibration-sensing system is proposed, which is based on self-interference of Rayleigh backscattering with phase-generated carrier (PGC) demodulation algorithm. Pulsed lights are sent into the sensing fiber and the Rayleigh backscattering light from a certain position along the sensing fiber would interfere through an unbalanced Michelson interferometry to generate the interference light. An improved PGC demodulation algorithm is carried out to recover the phase information of the interference signal, which carries the sensing information. Three vibration events were applied simultaneously to different positions over 2000 m sensing fiber and demodulated correctly. The spatial resolution is 10 m, and the noise level of the Φ-OTDR system we proposed is about 10-3 rad/\\surd {Hz}, and the signal-to-noise ratio is about 30.34 dB.

  14. Analysis of Optical Fiber Complex Propagation Matrix on the Basis of Vortex Modes

    DEFF Research Database (Denmark)

    Lyubopytov, Vladimir S.; Tatarczak, Anna; Lu, Xiaofeng

    2016-01-01

    We propose and experimentally demonstrate a novel method for reconstruction of the complex propagation matrix of optical fibers supporting propagation of multiple vortex modes. This method is based on the azimuthal decomposition approach and allows the complex matrix elements to be determined...... by direct calculations. We apply the proposed method to demonstrate the feasibility of optical compensation for coupling between vortex modes in optical fiber....

  15. A Method Using Optical Contactless Displacement Sensors to Measure Vibration Stress of Small-Bore Piping.

    Science.gov (United States)

    Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu

    2014-02-01

    In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.

  16. Vibrational mode frequencies of silica species in SiO2-H2O liquids and glasses from ab initio molecular dynamics.

    Science.gov (United States)

    Spiekermann, Georg; Steele-MacInnis, Matthew; Schmidt, Christian; Jahn, Sandro

    2012-04-21

    Vibrational spectroscopy techniques are commonly used to probe the atomic-scale structure of silica species in aqueous solution and hydrous silica glasses. However, unequivocal assignment of individual spectroscopic features to specific vibrational modes is challenging. In this contribution, we establish a connection between experimentally observed vibrational bands and ab initio molecular dynamics (MD) of silica species in solution and in hydrous silica glass. Using the mode-projection approach, we decompose the vibrations of silica species into subspectra resulting from several fundamental structural subunits: The SiO(4) tetrahedron of symmetry T(d), the bridging oxygen (BO) Si-O-Si of symmetry C(2v), the geminal oxygen O-Si-O of symmetry C(2v), the individual Si-OH stretching, and the specific ethane-like symmetric stretching contribution of the H(6)Si(2)O(7) dimer. This allows us to study relevant vibrations of these subunits in any degree of polymerization, from the Q(0) monomer up to the fully polymerized Q(4) tetrahedra. Demonstrating the potential of this approach for supplementing the interpretation of experimental spectra, we compare the calculated frequencies to those extracted from experimental Raman spectra of hydrous silica glasses and silica species in aqueous solution. We discuss observed features such as the double-peaked contribution of the Q(2) tetrahedral symmetric stretch, the individual Si-OH stretching vibrations, the origin of the experimentally observed band at 970 cm(-1) and the ethane-like vibrational contribution of the H(6)Si(2)O(7) dimer at 870 cm(-1).

  17. Enhancement of single mode operation in coaxial optical waveguide using DB boundary conditions

    Science.gov (United States)

    Lohia, Pooja; Prajapati, Y.; Saini, J. P.; Rai, B. S.

    2014-11-01

    In this study, a competent numerical strategy to compute the dispersion of optical waveguides is presented and propagation of electromagnetic waves in a coaxial optical waveguide with DB boundary conditions is instigated. For this intend, cylindrical coordinates are here being used to derive the DB boundary conditions and to obtain field components for the modes. The propagation constant for the waveguide to be studied is determined by solving the Bessel and the modified Bessel functions. The cutoff frequencies for various lower order modes have been calculated and their dispersion characteristics are plotted correspondingly. The behavior of the coaxial optical waveguide under DB boundary conditions is shown to be significantly different from that of coaxial optical waveguide and conventional optical waveguide under traditional or tangential boundary conditions. Finally, the effect of waveguide dimensions on the mode cutoff frequencies and fabrication issues are also addressed.

  18. Phase sensitive distributed vibration sensing based on ultraweak fiber Bragg grating array using double-pulse

    Science.gov (United States)

    Liu, Tao; Wang, Feng; Zhang, Xuping; Zhang, Lin; Yuan, Quan; Liu, Yu; Yan, Zhijun

    2017-08-01

    A distributed vibration sensing technique using double-optical-pulse based on phase-sensitive optical time-domain reflectometry (ϕ-OTDR) and an ultraweak fiber Bragg grating (UWFBG) array is proposed for the first time. The single-mode sensing fiber is integrated with the UWFBG array that has uniform spatial interval and ultraweak reflectivity. The relatively high reflectivity of the UWFBG, compared with the Rayleigh scattering, gains a high signal-to-noise ratio for the signal, which can make the system achieve the maximum detectable frequency limited by the round-trip time of the probe pulse in fiber. A corresponding experimental ϕ-OTDR system with a 4.5 km sensing fiber integrated with the UWFBG array was setup for the evaluation of the system performance. Distributed vibration sensing is successfully realized with spatial resolution of 50 m. The sensing range of the vibration frequency can cover from 3 Hz to 9 kHz.

  19. An FEM-based AI approach to model parameter identification for low vibration modes of wind turbine composite rotor blades

    Science.gov (United States)

    Navadeh, N.; Goroshko, I. O.; Zhuk, Y. A.; Fallah, A. S.

    2017-11-01

    An approach to construction of a beam-type simplified model of a horizontal axis wind turbine composite blade based on the finite element method is proposed. The model allows effective and accurate description of low vibration bending modes taking into account the effects of coupling between flapwise and lead-lag modes of vibration transpiring due to the non-uniform distribution of twist angle in the blade geometry along its length. The identification of model parameters is carried out on the basis of modal data obtained by more detailed finite element simulations and subsequent adoption of the 'DIRECT' optimisation algorithm. Stable identification results were obtained using absolute deviations in frequencies and in modal displacements in the objective function and additional a priori information (boundedness and monotony) on the solution properties.

  20. Difference frequency generation spectroscopy as a vibrational optical activity measurement tool.

    Science.gov (United States)

    Cheon, Sangheon; Cho, Minhaeng

    2009-03-19

    Vibrational optical activity (VOA) of chiral molecules in condensed phases can be studied by using vibrational circular dichroism and Raman optical activity measurement techniques. Recently, IR-vis sum frequency generation has shown to be an alternative VOA measurement method. Such a three-wave-mixing method employing a polarization modulation technique can be a potentially useful VOA measurement tool. Here, a theoretical description of difference frequency generation (DFG) employing circularly polarized visible radiations is presented. Frequency scanning to obtain a VOA-DFG spectrum is achieved by controlling the difference between the two electronically nonresonant incident radiation frequencies. If the two incident beams are linearly polarized and their polarization directions are perpendicular to each other, one can selectively measure the all-electric-dipole-allowed chiral component of the DFG susceptibility. In addition, by using circularly polarized beams and taking the DFG difference intensity signal, which is defined as the difference between left and right circularly polarized DFG signals, additional chiral susceptibility components originating from the electric quadrupole transition can be measured. The DFG as a novel VOA measurement technique for solution samples containing chiral molecules will therefore be a useful coherent spectroscopic tool for determining absolute configuration of chiral molecules in condensed phases.

  1. Simulation of vibration-induced effect on plasma current measurement using a fiber optic current sensor.

    Science.gov (United States)

    Descamps, Frédéric; Aerssens, Matthieu; Gusarov, Andrei; Mégret, Patrice; Massaut, Vincent; Wuilpart, Marc

    2014-06-16

    An accurate measurement of the plasma current is of paramount importance for controlling the plasma magnetic equilibrium in tokamaks. Fiber optic current sensor (FOCS) technology is expected to be implemented to perform this task in ITER. However, during ITER operation, the vessel and the sensing fiber will be subject to vibrations and thus to time-dependent parasitic birefringence, which may significantly compromise the FOCS performance. In this paper we investigate the effects of vibrations on the plasma current measurement accuracy under ITER-relevant conditions. The simulation results show that in the case of a FOCS reflection scheme including a spun fiber and a Faraday mirror, the error induced by the vibrations is acceptable regarding the ITER current diagnostics requirements.

  2. Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

    Science.gov (United States)

    Torri, G. B.; Janssen, N. M. A.; Zeng, Z.; Rottenberg, X.; Karabacak, D. M.; Vandecasteele, M.; Van Hoof, C.; Puers, R.; Tilmans, H. A. C.

    2014-08-01

    This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems.

  3. Piezoelectric transduction of flexural modes in pre-stressed microbeam resonators

    International Nuclear Information System (INIS)

    Torri, G B; Rottenberg, X; Hoof, C Van; Puers, R; Tilmans, H A C; Janssen, N M A; Zeng, Z; Karabacak, D M; Vandecasteele, M

    2014-01-01

    This paper reports on the optimization of the design of piezoelectric transducer elements integrated on doubly-clamped microbeam resonators utilized as (bio)chemical sensors. We report and emphasize the often forgotten influence of membrane stresses on defining the dimensions and optimal position of the piezoelectric transducer elements. The study takes into account stress induced structural changes and provides models for the equivalent motional parameters of resonators with particular shapes of the transducers matching the flexural modes of vibration. The above is analyzed theoretically using numerical models and is confirmed by impedance measurements and optical measurements of fabricated doubly-clamped beam resonators. We propose various transducer designs and highlight the advantages of using higher order vibration modes by implementing specially designed mode matching transducer elements. It is concluded that the paper describes and highlights the importance of accounting for the membrane stresses to optimize the resonator performance and the low power in electronic feedback of resonating sensing systems. (paper)

  4. Mode-field half-widths of Gaussian approximation for the fundamental mode of two kinds of optical waveguides

    International Nuclear Information System (INIS)

    Lian-Huang, Li; Fu-Yuan, Guo

    2009-01-01

    This paper analyzes the characteristic of matching efficiency between the fundamental mode of two kinds of optical waveguides and its Gaussian approximate field. Then, it presents a new method where the mode-field half-width of Gaussian approximation for the fundamental mode should be defined according to the maximal matching efficiency method. The relationship between the mode-field half-width of the Gaussian approximate field obtained from the maximal matching efficiency and normalized frequency is studied; furthermore, two formulas of mode-field half-widths as a function of normalized frequency are proposed

  5. 3D finite element simulation of optical modes in VCSELs

    OpenAIRE

    Rozova, M.; Pomplun, J.; Zschiedrich, L.; Schmidt, F.; Burger, S.

    2011-01-01

    We present a finite element method (FEM) solver for computation of optical resonance modes in VCSELs. We perform a convergence study and demonstrate that high accuracies for 3D setups can be attained on standard computers. We also demonstrate simulations of thermo-optical effects in VCSELs.

  6. The influence of flywheel micro vibration on space camera and vibration suppression

    Science.gov (United States)

    Li, Lin; Tan, Luyang; Kong, Lin; Wang, Dong; Yang, Hongbo

    2018-02-01

    Studied the impact of flywheel micro vibration on a high resolution optical satellite that space-borne integrated. By testing the flywheel micro vibration with six-component test bench, the flywheel disturbance data is acquired. The finite element model of the satellite was established and the unit force/torque were applied at the flywheel mounting position to obtain the micro vibration data of the camera. Integrated analysis of the data of the two parts showed that the influence of flywheel micro vibration on the camera is mainly concentrated around 60-80 Hz and 170-230 Hz, the largest angular displacement of the secondary mirror along the optical axis direction is 0.04″ and the maximum angular displacement vertical to optical axis is 0.032″. After the design and installation of vibration isolator, the maximum angular displacement of the secondary mirror is 0.011″, the decay rate of root mean square value of the angular displacement is more than 50% and the maximum is 96.78%. The whole satellite was suspended to simulate the boundary condition on orbit; the imaging experiment results show that the image motion caused by the flywheel micro vibrationis less than 0.1 pixel after installing the vibration isolator.

  7. A novel signal compression method based on optimal ensemble empirical mode decomposition for bearing vibration signals

    Science.gov (United States)

    Guo, Wei; Tse, Peter W.

    2013-01-01

    Today, remote machine condition monitoring is popular due to the continuous advancement in wireless communication. Bearing is the most frequently and easily failed component in many rotating machines. To accurately identify the type of bearing fault, large amounts of vibration data need to be collected. However, the volume of transmitted data cannot be too high because the bandwidth of wireless communication is limited. To solve this problem, the data are usually compressed before transmitting to a remote maintenance center. This paper proposes a novel signal compression method that can substantially reduce the amount of data that need to be transmitted without sacrificing the accuracy of fault identification. The proposed signal compression method is based on ensemble empirical mode decomposition (EEMD), which is an effective method for adaptively decomposing the vibration signal into different bands of signal components, termed intrinsic mode functions (IMFs). An optimization method was designed to automatically select appropriate EEMD parameters for the analyzed signal, and in particular to select the appropriate level of the added white noise in the EEMD method. An index termed the relative root-mean-square error was used to evaluate the decomposition performances under different noise levels to find the optimal level. After applying the optimal EEMD method to a vibration signal, the IMF relating to the bearing fault can be extracted from the original vibration signal. Compressing this signal component obtains a much smaller proportion of data samples to be retained for transmission and further reconstruction. The proposed compression method were also compared with the popular wavelet compression method. Experimental results demonstrate that the optimization of EEMD parameters can automatically find appropriate EEMD parameters for the analyzed signals, and the IMF-based compression method provides a higher compression ratio, while retaining the bearing defect

  8. Free-space optics mode-wavelength division multiplexing system using LG modes based on decision feedback equalization

    Science.gov (United States)

    Amphawan, Angela; Ghazi, Alaan; Al-dawoodi, Aras

    2017-11-01

    A free-space optics mode-wavelength division multiplexing (MWDM) system using Laguerre-Gaussian (LG) modes is designed using decision feedback equalization for controlling mode coupling and combating inter symbol interference so as to increase channel diversity. In this paper, a data rate of 24 Gbps is achieved for a FSO MWDM channel of 2.6 km in length using feedback equalization. Simulation results show significant improvement in eye diagrams and bit-error rates before and after decision feedback equalization.

  9. Sub-THz spectroscopic characterization of vibrational modes in artificially designed DNA monocrystal

    International Nuclear Information System (INIS)

    Sizov, Igor; Rahman, Masudur; Gelmont, Boris; Norton, Michael L.; Globus, Tatiana

    2013-01-01

    Highlights: • Sub-THz spectroscopy is used to characterize artificially designed DNA monocrystal. • Results are obtained using a novel near field, RT, frequency domain spectrometer. • Narrow resonances of 0.1 cm −1 width in absorption spectra of crystal are observed. • Signature measured between 310 and 490 GHz is reproducible and well resolved. • Absorption pattern is explained in part by simulation results from dsDNA fragment. - Abstract: Sub-terahertz (sub-THz) vibrational spectroscopy is a new spectroscopic branch for characterizing biological macromolecules. In this work, highly resolved sub-THz resonance spectroscopy is used for characterizing engineered molecular structures, an artificially designed DNA monocrystal, built from a short DNA sequence. Using a recently developed frequency domain spectroscopic instrument operating at room temperature with high spectral and spatial resolution, we demonstrated very intense and specific spectral lines from a DNA crystal in general agreement with a computational molecular dynamics (MD) simulation of a short double stranded DNA fragment. The spectroscopic signature measured in the frequency range between 310 and 490 GHz is rich in well resolved and reproducible spectral features thus demonstrating the capability of THz resonance spectroscopy to be used for characterizing custom macromolecules and structures designed and implemented via nanotechnology for a wide variety of application domains. Analysis of MD simulation indicates that intense and narrow vibrational modes with atomic movements perpendicular (transverse) and parallel (longitudinal) to the long DNA axis coexist in dsDNA, with much higher contribution from longitudinal vibrations

  10. New vibrational mode of the acoustic type in Nd(Pr)2 Cu O4 single crystals

    International Nuclear Information System (INIS)

    Fil', D.V.; Kolobov, I.G.; Fil', V.D.; Barilo, S.N.; Zhigunov, D.I.

    1995-01-01

    Sound velocities along main symmetry directions as well as their angle dependences in (100),(110)-type planes are measured in Nd(Pr) 2 Cu O 4 . Anomalies in the angle dependences are found, which are interpreted as a result of the interaction of elastic vibrations with an additional plane mode of the acoustic type. According to the proposed interpretation, the bare spectrum of the additional mode is two-dimensional, and the origin of the mode is connected with the electron degrees of freedom in the Cu O 2 -planes. A phenomenological model for description of acoustic mode spectra in the investigated systems is proposed. On the basis of the anion model of HTSC, a possible microscopic scenario of the appearance of the additional mode is analyzed. In the framework of the phenomenological model, the Debye temperatures are computed, which are in agreement with the specific heat data. The values of the components of the elastic moduli tensor are given

  11. Mechanisms of Coupled Vibrational Relaxation and Dissociation in Carbon Dioxide.

    Science.gov (United States)

    Armenise, Iole; Kustova, Elena

    2018-05-21

    A complete vibrational state-specific kinetic scheme describing dissociating carbon dioxide mixtures is proposed. CO 2 symmetric, bending and asymmetric vibrations and dissociation-recombination are strongly coupled through inter-mode vibrational energy transfers. Comparative study of state-resolved rate coefficients is carried out; the effect of different transitions may vary considerably with temperature. A non-equilibrium 1-D boundary layer flow typical to hypersonic planetary entry is studied in the state-to-state approach. To assess the sensitivity of fluid-dynamic variables and heat transfer to various vibrational transitions and chemical reactions, corresponding processes are successively included to the kinetic scheme. It is shown that vibrational-translational (VT) transitions in the symmetric and asymmetric modes do not alter the flow and can be neglected whereas the VT 2 exchange in the bending mode is the main channel of vibrational relaxation. Inter-mode vibrational exchanges affect the flow implicitly, through energy redistribution enhancing VT relaxation; the dominating role belongs to near-resonant transitions between symmetric and bending modes as well as between CO molecules and CO 2 asymmetric mode. Strong coupling between VT 2 relaxation and chemical reactions is emphasized. While vibrational distributions and average vibrational energy show strong dependence on the kinetic scheme, the heat flux is more sensitive to chemical reactions.

  12. Can Internal Conversion BE Controlled by Mode-Specific Vibrational Excitation in Polyatomic Molecules

    Science.gov (United States)

    Portnov, Alexander; Epshtein, Michael; Bar, Ilana

    2017-06-01

    Nonadiabatic processes, dominated by dynamic passage of reactive fluxes through conical intersections (CIs) are considered to be appealing means for manipulating reaction paths. One approach that is considered to be effective in controlling the course of dissociation processes is the selective excitation of vibrational modes containing a considerable component of motion. Here, we have chosen to study the predissociation of the model test molecule, methylamine and its deuterated isotopologues, excited to well-characterized quantum states on the first excited electronic state, S_{1}, by following the N-H(D) bond fission dynamics through sensitive H(D) photofragment probing. The branching ratios between slow and fast H(D) photofragments, the internal energies of their counter radical photofragments and the anisotropy parameters for fast H photofragments, confirm correlated anomalies for predissociation initiated from specific rovibronic states, reflecting the existence of a dynamic resonance in each molecule. This resonance strongly depends on the energy of the initially excited rovibronic states, the evolving vibrational mode on the repulsive S_{1} part during N-H(D) bond elongation, and the manipulated passage through the CI that leads to radicals excited with C-N-H(D) bending and preferential perpendicular bond breaking, relative to the photolyzing laser polarization, in molecules containing the NH_{2} group. The indicated resonance plays an important role in the bifurcation dynamics at the CI and can be foreseen to exist in other photoinitiated processes and to control their outcome.

  13. Turbo machine tip clearance and vibration measurements using a fibre optic laser Doppler position sensor

    Science.gov (United States)

    Pfister, T.; Büttner, L.; Czarske, J.; Krain, H.; Schodl, R.

    2006-07-01

    This paper presents a novel fibre optic laser Doppler position sensor for single blade tip clearance and vibration measurements at turbo machines, which offers high temporal resolution and high position resolution simultaneously. The sensor principle is based on the generation of a measurement volume consisting of two superposed fan-like interference fringe systems with contrary fringe spacing gradients using wavelength division multiplexing. A flexible and robust measurement system with an all-passive fibre coupled measurement head has been realized employing diffractive and refractive optics. Measurements of tip clearance and rotor vibrations at a transonic centrifugal compressor performed during operation at up to 50 000 rpm (833 Hz) corresponding to 21.7 kHz blade frequency and 586 m s-1 blade tip velocity are presented. The results are in excellent agreement with those of capacitive probes. The mean uncertainty of the position measurement was around 20 µm and, thus, considerably better than for conventional tip clearance probes. Consequently, this sensor is capable of fulfilling the requirements for future active clearance control systems and has great potential for in situ and online tip clearance and vibration measurements at metallic and non-metallic turbine blades with high precision.

  14. Spectroscopic and non-linear optical studies of two novel optical limiters from dichloroaniline family crystals: 3,4-Dichloroaniline and 3,5-dichloroaniline

    Science.gov (United States)

    Sasikala, V.; Sajan, D.; Joseph, Lynnette; Narayana, Badiadka; Sarojini, Balladka K.

    2017-11-01

    Two organic crystals of the isomeric forms of dichloroanilines such as 3, 4-dichloroaniline (3,4-DCA) and 3, 5-dichloroaniline (3,5-DCA) were grown by slow evaporation method and characterized by various analytical techniques. The vibrational normal modes of the samples were theoretically predicted using the scaled quantum mechanical force field procedures with the DFT level calculation and the potential energy distributions of the individual modes were estimated using the normal coordinate analysis. Fermi doublets and Evans holes were identified in the vibrational spectra of samples. The nuclear relaxation contribution to the vibrational polarizabilities and hyperpolarizabilities for the normal modes of the molecules were quantitatively estimated using the DFT method. The results of the calculated NLO responses showed that the vibrational mean contributions to the static polarizabilities and hyperpolarizabilities were smaller than the corresponding electronic contributions for the molecules. The Kurtz and Perry powder SHG efficiencies were measured and both samples have generated the second-harmonics of the fundamentals. The open-aperture Z-scan study results proposed the superior optical limiting property of 3,5-DCA with respect to 3,4-DCA.

  15. Modeling of mode-locked coupled-resonator optical waveguide lasers

    DEFF Research Database (Denmark)

    Agger, Christian; Skovgård, Troels Suhr; Gregersen, Niels

    2010-01-01

    Coupled-resonator optical waveguides made from coupled high-Q photonic crystal nanocavities are investigated for use as cavities in mode-locked lasers. Such devices show great potential in slowing down light and can serve to reduce the cavity length of a mode-locked laser. An explicit expression...... of the emerging pulse train. A range of tuning around this frequency allows for effective mode locking. Finally, noise is added to the generalized single-cavity eigenfrequencies in order to evaluate the effects of fabrication imperfections on the cold-cavity transmission properties and consequently on the locking...

  16. Vibrational quasi-continuum in unimolecular multiphoton dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Fernandez, P.; Gonzalez-Diaz, P.F.

    1987-04-01

    The vibrational quasi-continuum of the boron trifluoride molecule has been qualitatively studied and the formalism extended to treat N-normal-mode molecules. The anharmonic potential curves for the BF/sub 3/ normal modes have been calculated, and the computed anharmonicity constants have been tested against the fundamental frequencies. The potential curve of the wagging mode has been simulated by an internal rotation of one of the fluoride atoms. The vibrational-energy levels and wave functions have been calculated applying second-order perturbation theory. The quasi-continuum energy levels of BF/sub 3/ have been obtained by means of a method based in forming adequate linear combinations of wave functions belonging to the N-1 modes resulting from removing the i.r.-active mode;the associated energies have been minimized using a constrained minimization procedure. It has been found that the energy pattern of the N-1 vibrational modes possesses an energy density high enough for constituting a vibrational heat bath and, finally, it has been verified that the ''fictitious'' pattern of the active mode is included in the pattern of the N-1 modes.

  17. Semiconductor Mode-Locked Lasers for Optical Communication Systems

    DEFF Research Database (Denmark)

    Yvind, Kresten

    2003-01-01

    The thesis deals with the design and fabrication of semiconductor mode-locked lasers for use in optical communication systems. The properties of pulse sources and characterization methods are described as well as requirements for application in communication systems. Especially, the importance of...

  18. Free-space optics mode-wavelength division multiplexing system using LG modes based on decision feedback equalization

    Directory of Open Access Journals (Sweden)

    Amphawan Angela

    2017-01-01

    Full Text Available A free-space optics mode-wavelength division multiplexing (MWDM system using Laguerre-Gaussian (LG modes is designed using decision feedback equalization for controlling mode coupling and combating inter symbol interference so as to increase channel diversity. In this paper, a data rate of 24 Gbps is achieved for a FSO MWDM channel of 2.6 km in length using feedback equalization. Simulation results show significant improvement in eye diagrams and bit-error rates before and after decision feedback equalization.

  19. Optical Field-Strength Polarization of Two-Mode Single-Photon States

    Science.gov (United States)

    Linares, J.; Nistal, M. C.; Barral, D.; Moreno, V.

    2010-01-01

    We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of…

  20. Tunable orbital angular momentum mode filter based on optical geometric transformation.

    Science.gov (United States)

    Huang, Hao; Ren, Yongxiong; Xie, Guodong; Yan, Yan; Yue, Yang; Ahmed, Nisar; Lavery, Martin P J; Padgett, Miles J; Dolinar, Sam; Tur, Moshe; Willner, Alan E

    2014-03-15

    We present a tunable mode filter for spatially multiplexed laser beams carrying orbital angular momentum (OAM). The filter comprises an optical geometric transformation-based OAM mode sorter and a spatial light modulator (SLM). The programmable SLM can selectively control the passing/blocking of each input OAM beam. We experimentally demonstrate tunable filtering of one or multiple OAM modes from four multiplexed input OAM modes with vortex charge of ℓ=-9, -4, +4, and +9. The measured output power suppression ratio of the propagated modes to the blocked modes exceeds 14.5 dB.

  1. Vibration sensing in flexible structures using a distributed-effect modal domain optical fiber sensor

    Science.gov (United States)

    Reichard, Karl M.; Lindner, Douglas K.; Claus, Richard O.

    1991-01-01

    Modal domain optical fiber sensors have recently been employed in the implementation of system identification algorithms and the closed-loop control of vibrations in flexible structures. The mathematical model of the modal domain optical fiber sensor used in these applications, however, only accounted for the effects of strain in the direction of the fiber's longitudinal axis. In this paper, we extend this model to include the effects of arbitrary stress. Using this sensor model, we characterize the sensor's sensitivity and dynamic range.

  2. Monolithic optofluidic mode coupler for broadband thermo- and piezo-optical characterization of liquids.

    Science.gov (United States)

    Pumpe, Sebastian; Chemnitz, Mario; Kobelke, Jens; Schmidt, Markus A

    2017-09-18

    We present a monolithic fiber device that enables investigation of the thermo- and piezo-optical properties of liquids using straightforward broadband transmission measurements. The device is a directional mode coupler consisting of a multi-mode liquid core and a single-mode glass core with pronounced coupling resonances whose wavelength strongly depend on the operation temperature. We demonstrated the functionality and flexibility of our device for carbon disulfide, extending the current knowledge of the thermo-optic coefficient by 200 nm at 20 °C and uniquely for high temperatures. Moreover, our device allows measuring the piezo-optic coefficient of carbon disulfide, confirming results first obtained by Röntgen in 1891. Finally, we applied our approach to obtain the dispersion of the thermo-optic coefficients of benzene and tetrachloroethylene between 450 and 800 nm, whereas no data was available for the latter so far.

  3. Vibrational and thermal study of l-methionine nitrate polycrystals

    Energy Technology Data Exchange (ETDEWEB)

    Victor, F.M.S.; Ribeiro, L.H.L.; Facanha Filho, P.F.; Santos, C.A.S.; Soares, R.A.; Abreu, D.C.; Sousa, J.C.F.; Carvalho, J.O.; Santos, A.O. dos [Universidade Federal do Maranhao (UFMA), MA (Brazil)

    2016-07-01

    Full text: Intensified in studies of nonlinear optical materials has been observed over the past two decades for its wide application in telecommunications, optical modulation and optical signal processing. The goal of this work is the thermal and vibrational study of L-methionine nitrate polycrystalline. The polycrystals were obtained by the method of slow evaporation of solvent at ambient temperature of 25 ° C. The X-ray diffraction was performed to confirm the structure of the material, which has monoclinic structure (space group P21) with four molecules per unit cell structure. Refinement by Rietveld method has been optimized and good quality parameters Rwp = 7.97% , Rp = 5.74 and S = 1.92%. The thermal stability of the material was verified from Thermogravimetric analysis (TGA), Differential Thermal Analysis (DTA) and Differential Scanning Calorimetry (DSC). The measures showed a possible phase transition event at about 107°C before the melting point of the material, which took place at about 127°C. Thermogravimetric analysis showed two mass loss events of 61.5% and 30.4%. The vibrational modes of the L-methionine nitrate molecule were identified by Raman spectroscopy in the spectral range between 35cm-1 and 3500 cm-1, the scattering measurements were made from room temperature up to the melting temperature of the material (140 ° C ) in which the disappearance of bands was found in the region of normal modes at 130 ° C, thus demonstrating a irreversible structural phase transition, because the spectrum obtained after returning the sample to ambient temperature is typical of amorphous material. (author)

  4. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  5. Franck-Condon fingerprinting of vibration-tunneling spectra.

    Science.gov (United States)

    Berrios, Eduardo; Sundaradevan, Praveen; Gruebele, Martin

    2013-08-15

    We introduce Franck-Condon fingerprinting as a method for assigning complex vibration-tunneling spectra. The B̃ state of thiophosgene (SCCl2) serves as our prototype. Despite several attempts, assignment of its excitation spectrum has proved difficult because of near-degenerate vibrational frequencies, Fermi resonance between the C-Cl stretching mode and the Cl-C-Cl bending mode, and large tunneling splittings due to the out-of-plane umbrella mode. Hence, the spectrum has never been fitted to an effective Hamiltonian. Our assignment approach replaces precise frequency information with intensity information, eliminating the need for double resonance spectroscopy or combination differences, neither of which have yielded a full assignment thus far. The dispersed fluorescence spectrum of each unknown vibration-tunneling state images its character onto known vibrational progressions in the ground state. By using this Franck-Condon fingerprint, we were able to determine the predominant character of several vibration-tunneling states and assign them; in other cases, the fingerprinting revealed that the states are strongly mixed and cannot be characterized with a simple normal mode assignment. The assigned transitions from vibration-tunneling wave functions that were not too strongly mixed could be fitted within measurement uncertainty by an effective vibration-tunneling Hamiltonian. A fit of all observed vibration-tunneling states will require a full resonance-tunneling Hamiltonian.

  6. Multi-mode electro-mechanical vibrations of a microtubule: In silico demonstration of electric pulse moving along a microtubule

    Czech Academy of Sciences Publication Activity Database

    Havelka, Daniel; Cifra, Michal; Kučera, Ondřej

    2014-01-01

    Roč. 104, č. 24 (2014), s. 243702 ISSN 0003-6951 R&D Projects: GA ČR(CZ) GAP102/11/0649 Institutional support: RVO:67985882 Keywords : Biophysical mechanism * Collective vibration mode * Electro-mechanical Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.302, year: 2014

  7. Vibrational properties of homopolar and heteropolar surfaces and interfaces of the CdTe/HgTe system

    International Nuclear Information System (INIS)

    Rey Gonzalez, R.; Camacho B, A.; Quiroga, L.

    1993-08-01

    We present results of calculations for the density of vibrational modes for (001) and (111) homopolar, as well as for (011) heteropolar free surfaces of CdTe and HgTe. A rigid-ion model with a dynamical matrix parametrization including force constants up to second neighbours is used. We report on the existence of highly localized surface resonant modes at the top of the acoustic branch for CdTe and the bottom of the optical branch for HgTe. A different behaviour in the three directions analysed is found. The interface atomic planes show themselves as phonon gapless layers. The contribution of in-plane and out-of-plane vibration is analysed for both the surface and interface cases. (author). 7 refs, 7 figs

  8. Coherent optical effect on time-resolved vibrational SFG spectrum of adsorbates

    Science.gov (United States)

    Ueba, H.; Sawabu, T.; Mii, T.

    2002-04-01

    We present a theory to study the influence of the coherent mixing between pump-infrared and probe-visible pulse on a time-resolved sum-frequency generation (TR-SFG) spectrum for vibrations at surfaces. The general formula of the time-dependent and its Fourier transform of the SFG polarization and its Fourier transform allows us to calculate the time-resolved vibrational SFG spectrum and the transient characteristics of the SFG intensity as a function of the delay time td between the pump-infrared and probe-visible pulse. It is found the coherent optical effect manifests itself in the broadening and narrowing of the SFG spectrum with the intrinsic width of T2 at negative and positive td, respectively, being in qualitative agreement with recent experimental results. The influence of the coherent mixing on the transient behavior of the SFG intensity is also discussed in conjunction to the T2 determination.

  9. Variant of multimodal vibration damping of electroviscoelastic structures by appropriate choice of external electric circuit parameters

    Directory of Open Access Journals (Sweden)

    Dmitrii A. Oshmarin

    2016-09-01

    Full Text Available In technical applications it takes place the problem of vibration damping in certain regions of the structure, at the location of optical sensors for instance, at any external dynamic excitations with no mass increase and no changes in spectral portrait. In order to solve these problems it is widespread the use of special damping devices: piezoelectric elements connected to external electric circuits and attached to the structure. It became possible due to piezoelectric effect, which provides transformation of part of energy of vibrations into electric one, which is dissipated in external electric circuit. So that by using appropriate electric circuits one may dissipate internal energy and therefore reduce structural vibrations in definite frequency range. As a rule, external circuit of single branch, which shunts single piezoelectric element, allows vibration damping on one certain frequency. Due to the fact, that practical applications usually include requirements of damping of several modes by one and the same technical devices, the problem of multimodal vibration damping in smart-structures is rather acute. The objective of this paper is the study of possibility of vibration damping on several modes by using single external series RL-circuit, connected to electrodes of single piezoelectric element on the basis of solution of problems on natural and forced steady-state vibrations of electroelastic systems with external electric circuits.

  10. Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

    Science.gov (United States)

    Kim, Jimyung; Delfyett, Peter J

    2008-07-21

    We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

  11. Exact decoherence dynamics of a single-mode optical field

    International Nuclear Information System (INIS)

    An, J.-H.; Yeo Ye; Oh, C.H.

    2009-01-01

    We apply the influence-functional method of Feynman and Vernon to the study of a single-mode optical field that interacts with an environment at zero temperature. Using the coherent-state formalism of the path integral, we derive a generalized master equation for the single-mode optical field. Our analysis explicitly shows how non-Markovian effects manifest in the exact decoherence dynamics for different environmental correlation time scales. Remarkably, when these are equal to or greater than the time scale for significant change in the system, the interplay between the backaction-induced coherent oscillation and the dissipative effect of the environment causes the non-Markovian effect to have a significant impact not only on the short-time behavior but also on the long-time steady-state behavior of the system.

  12. The 1989 progress report: quantum optics

    International Nuclear Information System (INIS)

    Flytzanis, C.

    1989-01-01

    The 1989 progress report of the laboratory of Quantum Optics of the Polytechnic School (France) is presented. The main research activity of the Laboratory is the study of processes controlling the behavior of matter under the action of high intensity light fields and under space-time constraints. The reported investigations were performed in the following fields: dynamics and vibrational relaxation modes in dense phases; nonlinear optical properties of composite materials; surface energy transfer and distribution in molecule surface interactions. Techniques relating to femtosecond impulsions, pulsating Raman and nonlinear optics were developed. The published papers, the conferences and the Laboratory staff are listed [fr

  13. A deterministic guide for material and mode dependence of on-chip electro-optic modulator performance

    Science.gov (United States)

    Amin, Rubab; Suer, Can; Ma, Zhizhen; Sarpkaya, Ibrahim; Khurgin, Jacob B.; Agarwal, Ritesh; Sorger, Volker J.

    2017-10-01

    Electro-optic modulation is a key function in optical data communication and possible future optical computing engines. The performance of modulators intricately depends on the interaction between the actively modulated material and the propagating waveguide mode. While high-performing modulators were demonstrated before, the approaches were taken as ad-hoc. Here we show the first systematic investigation to incorporate a holistic analysis for high-performance and ultra-compact electro-optic modulators on-chip. We show that intricate interplay between active modulation material and optical mode plays a key role in the device operation. Based on physical tradeoffs such as index modulation, loss, optical confinement factors and slow-light effects, we find that bias-material-mode regions exist where high phase modulation and high loss (absorption) modulation is found. This work paves the way for a holistic design rule of electro-optic modulators for on-chip integration.

  14. Few-mode fiber, splice and SDM component characterization by spatially-diverse optical vector network analysis

    DEFF Research Database (Denmark)

    Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner

    2017-01-01

    This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel ...... in the few-mode multi-core fiber and their impact on system IL and MDL are analyzed, finding splices to cause significant mode-mixing and to be non-negligible in system capacity analysis.......This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel...... photonic lantern spatial multiplexer, coupled to a 36-core 3-mode fiber, is experimentally demonstrated, extracting the full impulse response and complex transfer function matrices as well as insertion loss (IL) and mode-dependent loss (MDL) data. Moreover, the mode-mixing behavior of fiber splices...

  15. Axisymmetric vibrations of thick shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)

  16. Observation of coherent optical phonons excited by femtosecond laser radiation in Sb films by ultrafast electron diffraction method

    Energy Technology Data Exchange (ETDEWEB)

    Mironov, B. N.; Kompanets, V. O.; Aseev, S. A., E-mail: isanfemto@yandex.ru [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation); Ischenko, A. A. [Moscow Technological University, Institute of High Chemical Technologies (Russian Federation); Kochikov, I. V. [Moscow State University (Russian Federation); Misochko, O. V. [Russian Academy of Sciences, Institute of Solid State Physics (Russian Federation); Chekalin, S. V.; Ryabov, E. A. [Russian Academy of Sciences, Institute of Spectroscopy (Russian Federation)

    2017-03-15

    The generation of coherent optical phonons in a polycrystalline antimony film sample has been investigated using femtosecond electron diffraction method. Phonon vibrations have been induced in the Sb sample by the main harmonic of a femtosecond Ti:Sa laser (λ = 800 nm) and probed by a pulsed ultrashort photoelectron beam synchronized with the pump laser. The diffraction patterns recorded at different times relative to the pump laser pulse display oscillations of electron diffraction intensity corresponding to the frequencies of vibrations of optical phonons: totally symmetric (A{sub 1g}) and twofold degenerate (E{sub g}) phonon modes. The frequencies that correspond to combinations of these phonon modes in the Sb sample have also been experimentally observed.

  17. On the fundamental mode of the optical resonator with toroidal mirrors

    Energy Technology Data Exchange (ETDEWEB)

    Serednyakov, S.S.; Vinokurov, N.A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation)

    1995-12-31

    The fundamental mode of the optical resonator with the toroidal mirrors is investigated. The losses in such resonator with the on-axis holes are low in compare with the case of spherical mirrors. The use of this type of optical resonator is briefly discussed.

  18. Electrical Characteristics of the Contour-Vibration-Mode Piezoelectric Transformer with Ring/Dot Electrode Area Ratio

    Science.gov (United States)

    Yoo, Juhyun; Yoon, Kwanghee; Lee, Yongwoo; Suh, Sungjae; Kim, Jongsun; Yoo, Chungsik

    2000-05-01

    Contour-vibration-mode Pb(Sb1/2Nb1/2)O3-Pb(Zr, Ti)O3 [PSN-PZT] piezoelectric transformers with different ring/dot electrode area ratios were fabricated to the size of 27.5× 27.5× 2.5 mm3 by cold isostatic pressing. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. Efficiencies above 90% with load resistance were obtained from all the transformers. The voltage step-up ratio appeared to be proportional to the dot electrode area. A 14 W fluorescent lamp, T5, was successfully driven by all of the fabricated transformers. The transformer with ring/dot electrode area ratio of 4.85 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 14.88 W, 98% and 5°C, respectively.

  19. Holograms for laser diode: Single mode optical fiber coupling

    Science.gov (United States)

    Fuhr, P. L.

    1982-01-01

    The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

  20. Analysis of Few-Mode Multi-Core Fiber Splice Behavior Using an Optical Vector Network Analyzer

    DEFF Research Database (Denmark)

    Rommel, Simon; Mendinueta, Jose Manuel Delgado; Klaus, Werner

    2017-01-01

    The behavior of splices in a 3-mode 36-core fiber is analyzed using optical vector network analysis. Time-domain response analysis confirms splices may cause significant mode-mixing, while frequency-domain analysis shows splices may affect system level mode-dependent loss both positively and negativ......The behavior of splices in a 3-mode 36-core fiber is analyzed using optical vector network analysis. Time-domain response analysis confirms splices may cause significant mode-mixing, while frequency-domain analysis shows splices may affect system level mode-dependent loss both positively...

  1. Structure of modes of smoothly irregular three-dimensional integrated optical four-layer waveguide

    International Nuclear Information System (INIS)

    Egorov, A.A.; Ajryan, Eh.A.; Sevast'yanov, A.L.; Sevast'yanov, L.A.

    2009-01-01

    As a method of research of an integrated optical multilayer waveguide, satisfying the condition of smooth modification of the shape of the studied three-dimensional structure, an asymptotic method is used. Three-dimensional fields of smoothly deforming modes of the integrated optical waveguide are circumscribed analytically. An evident dependence of the contributions of the first order of smallness in the amplitudes of the electrical and magnetic fields of the quasi-waveguide modes is obtained. The canonical type of the equations circumscribing propagation of quasi-TE and quasi-TM modes in the smoothly irregular part of a four-layer integrated optical waveguide is represented for an asymptotic method. With the help of the method of coupled waves and perturbation theory method, the shifts of complex propagation constants for quasi-TE and quasi-TM modes are obtained in an explicit form. The elaborated theory is applicable for the analysis of similar structures of dielectric, magnetic and metamaterials in a sufficiently broad band of electromagnetic wavelengths

  2. Dual-mode optical fiber-based tweezers for robust trapping and manipulation of absorbing particles in air

    Science.gov (United States)

    Sil, Souvik; Kanti Saha, Tushar; Kumar, Avinash; Bera, Sudipta K.; Banerjee, Ayan

    2017-12-01

    We develop an optical tweezers system using a single dual-mode optical fiber where mesoscopic absorbing particles can be trapped in three dimensions and manipulated employing photophoretic forces. We generate a superposition of fundamental and first order Hermite-Gaussian beam modes by the simple innovation of coupling a laser into a commercial optical fiber designed to be single mode for a wavelength higher than that of the laser. We achieve robust trapping of the absorbing particles for hours using both the pure fundamental and superposition mode beams and attain large manipulation velocities of ˜5 mm s-1 in the axial direction and ˜0.75 mm s-1 in the radial direction. We then demonstrate that the superposition mode is more effective in trapping and manipulation compared to the fundamental mode by around 80%, which may be increased several times by the use of a pure first order Hermite-Gaussian mode. The work has promising implications for trapping and spectroscopy of aerosols in air using simple optical fiber-based traps.

  3. Natural vibration experimental analysis of Novovoronezhskaya NPP main building

    International Nuclear Information System (INIS)

    Zoubkov, D.; Isaikin, A.; Shablinsky, G.; Lopanchuk, A.; Nefedov, S.

    2005-01-01

    1. Natural vibration frequencies are main characteristics of buildings and structures which allow to give integral estimation of their in-service state. Even relatively small changes of these frequencies as compared to the initially registered values point to serious defects of building structures. In this paper we analyzed natural vibration frequencies and natural modes of the main building (MB) of Novovoronezhskaya NPP operating nuclear unit with WWER-440 type reactor. The MB consists of a reactor compartment (RC), a machine room (MR) and an electric device (ED) unit positioned in between. 2. Natural vibration frequencies and natural modes of the MB were determined experimentally by analyzing its microvibrations caused by operation of basic equipment (turbines, pumps, etc.). Microvibrations of the main building were measured at 12 points. At each point measurements were carried out along two or three mutually perpendicular vibration directions. Spectral analysis of vibration records has been conducted. Identification of natural vibration frequencies was carried out on the basis of the spectral peaks and plotted vibration modes (taking into account operating frequencies of the basic equipment of the power generating unit). On the basis of the measurement results three transverse modes and corresponding natural vibration frequencies of the MB, one longitudinal mode and corresponding natural vibration frequency of the MB and two natural frequencies of vertical vibrations of RC and MR floor trusses (1st and 2nd symmetric forms) were determined. Dynamic characteristics of the main building of NV NPP resulting from full scale researches are supposed to be used as one of building structure stability criteria. (authors)

  4. Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing

    Directory of Open Access Journals (Sweden)

    Ming Ma

    2016-11-01

    Full Text Available All-optical signal processing based on nonlinear optical effects allows for the realization of important functions in telecommunications including wavelength conversion, optical multiplexing/demultiplexing, Fourier transformation, and regeneration, amongst others, on ultrafast time scales to support high data rate transmission. In integrated photonic subsystems, the majority of all-optical signal processing systems demonstrated to date typically process only a single channel at a time or perform a single processing function, which imposes a serious limitation on the functionality of integrated solutions. Here, we demonstrate how nonlinear optical effects can be harnessed in a mode-selective manner to perform simultaneous multi-channel (two and multi-functional optical signal processing (i.e., regenerative wavelength conversion in an integrated silicon photonic device. This approach, which can be scaled to a higher number of channels, opens up a new degree of freedom for performing a broad range of multi-channel nonlinear optical signal processing functions using a single integrated photonic device.

  5. Superconducting electron tunneling as detection method for low frequency resonant vibration modes of interstitials in fcc lead

    International Nuclear Information System (INIS)

    Adrian, H.

    1981-01-01

    The influence of crystal defects on the phonon spectra was studied for fcc lead using superconducting tunneling spectroscopy. The theory predicts low frequency modes for the vibrational states of interstitials in (100) dumbbell configuration. Low temperature irradiation of superconducting point contacts with fast ions (point contact thickness small compared to the average ion range) showed radiation-induced structures in the low-energy part of the Eliashberg function for lead. These resonant modes are reduced by annealing at 18.5 K; they are attributed to small interstitial clusters. The radiation-induced structures are completely removed by room temperature annealing. (orig.)

  6. Vibration monitoring of carbon fiber composites by multiple fiber optic sensors

    Science.gov (United States)

    Olivero, Massimo; Perrone, Guido; Vallan, Alberto; Chen, Wei; Tosi, Daniele

    2014-05-01

    This work presents the comparison between the fiber Bragg grating technology and a vibration-measurement technique based on the detection of polarization rotation (polarimetric sensor) in a standard optical fiber, applied to the dynamic structural monitoring of carbon reinforced composites for the automotive industry. A carbon reinforced composite test plate in a 4-layer configuration was equipped with fiber Bragg gratings and polarimetric fiber sensors, then it was mechanically stressed by static and dynamic loads while monitoring the sensors response. The fiber Bragg grating setup exhibited 1.15+/-0.0016 pm/kg static load response and reproduced dynamic excitation with 0.1% frequency uncertainty, while the polarimetric sensing system exhibited a sensitivity of 1.74+/-0.001 mV/kg and reproduced the dynamic excitation with 0.5% frequency uncertainty. It is shown that the polarimetric sensor technology represents a cheap yet efficient alternative to the fiber Bragg grating sensors in the case of vibration-monitoring of small structures at high frequency.

  7. Bridge SHM system based on fiber optical sensing technology

    Science.gov (United States)

    Li, Sheng; Fan, Dian; Fu, Jiang-hua; Huang, Xing; Jiang, De-sheng

    2015-09-01

    The latest progress of our lab in recent 10 years on the area of bridge structural health monitoring (SHM) based on optical fiber sensing technology is introduced. Firstly, in the part of sensing technology, optical fiber force test-ring, optical fiber vibration sensor, optical fiber smart cable, optical fiber prestressing loss monitoring method and optical fiber continuous curve mode inspection system are developed, which not only rich the sensor types, but also provides new monitoring means that are needed for the bridge health monitoring system. Secondly, in the optical fiber sensing network and computer system platform, the monitoring system architecture model is designed to effectively meet the integration scale and effect requirement of engineering application, especially the bridge expert system proposed integration of sensing information and informatization manual inspection to realize the mode of multi index intelligence and practical monitoring, diagnosis and evaluation. Finally, the Jingyue bridge monitoring system as the representative, the research on the technology of engineering applications are given.

  8. Crosstalk-aware virtual network embedding over inter-datacenter optical networks with few-mode fibers

    Science.gov (United States)

    Huang, Haibin; Guo, Bingli; Li, Xin; Yin, Shan; Zhou, Yu; Huang, Shanguo

    2017-12-01

    Virtualization of datacenter (DC) infrastructures enables infrastructure providers (InPs) to provide novel services like virtual networks (VNs). Furthermore, optical networks have been employed to connect the metro-scale geographically distributed DCs. The synergistic virtualization of the DC infrastructures and optical networks enables the efficient VN service over inter-DC optical networks (inter-DCONs). While the capacity of the used standard single-mode fiber (SSMF) is limited by their nonlinear characteristics. Thus, mode-division multiplexing (MDM) technology based on few-mode fibers (FMFs) could be employed to increase the capacity of optical networks. Whereas, modal crosstalk (XT) introduced by optical fibers and components deployed in the MDM optical networks impacts the performance of VN embedding (VNE) over inter-DCONs with FMFs. In this paper, we propose a XT-aware VNE mechanism over inter-DCONs with FMFs. The impact of XT is considered throughout the VNE procedures. The simulation results show that the proposed XT-aware VNE can achieves better performances of blocking probability and spectrum utilization compared to conventional VNE mechanisms.

  9. Structural, vibrational and theoretical studies of anilinium trichloroacetate: New hydrogen bonded molecular crystal with nonlinear optical properties

    Science.gov (United States)

    Tanak, H.; Pawlus, K.; Marchewka, M. K.; Pietraszko, A.

    2014-01-01

    In this work, we report a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of the potential nonlinear optical (NLO) material anilinium trichloroacetate. The FT-IR and FT-Raman spectra of the compound have been recorded together between 4000-80 cm-1 and 3600-80 cm-1 regions, respectively. The compound crystallizes in the noncentrosymmetric space group of monoclinic system. The optimized molecular structure, vibrational wavenumbers, IR intensities and Raman activities have been calculated by using density functional method (B3LYP) with 6-311++G(d,p) as higher basis set. The obtained vibrational wavenumbers and optimized geometric parameters were seen to be in good agreement with the experimental data. DSC measurements on powder samples do not indicate clearly on the occurrence of phase transitions in the temperature 113-293 K. The Kurtz and Perry powder reflection technique appeared to be very effective in studies of second-order nonlinear optical properties of the molecule. The non-linear optical properties are also addressed theoretically. The predicted NLO properties of the title compound are much greater than ones of urea. In addition, DFT calculations of the title compound, molecular electrostatic potential, frontier orbitals and thermodynamic properties were also performed at 6-311++G(d,p) level of theory. For title crystal the SHG efficiency was estimated by Kurtz-Perry method to be deff = 0.70 deff (KDP).

  10. Optical Splitters Based on Self-Imaging Effect in Multi-Mode Waveguide Made by Ion Exchange in Glass

    Directory of Open Access Journals (Sweden)

    O. Barkman

    2013-04-01

    Full Text Available Design and modeling of single mode optical multi-mode interference structures with graded refractive index is reported. Several samples of planar optical channel waveguides were obtained by Ag+, Na+ and K+, Na+ one step thermal ion exchange process in molten salt on GIL49 glass substrate and new special optical glass for ion exchange technology. Waveguide properties were measured by optical mode spectroscopy. Obtained data were used for further design and modeling of single mode channel waveguide and subsequently for the design of 1 to 3 multimode interference power splitter in order to improve simulation accuracy. Designs were developed by utilizing finite difference beam propagation method.

  11. Impact self-excited vibrations of linear motor

    Science.gov (United States)

    Zhuravlev, V. Ph.

    2010-08-01

    Impact self-exciting vibration modes in a linear motor of a monorail car are studied. Existence and stability conditions of self-exciting vibrations are found. Ways of avoiding the vibrations are discussed.

  12. Optimized geometry, vibration (IR and Raman spectra and nonlinear optical activity of p-nitroanilinium perchlorate molecule: A theoretical study

    Directory of Open Access Journals (Sweden)

    Tamer Ömer

    2016-03-01

    Full Text Available The molecular modeling of p-nitroanilinium perchlorate molecule was carried out by using B3LYP and HSEH1PBE levels of density functional theory (DFT. The IR and Raman spectra were simulated and the assignments of vibrational modes were performed on the basis of relative contribution of various internal co-ordinates. NBO analysis was performed to demonstrate charge transfer, conjugative interactions and the formation of intramolecular hydrogen bonding interactions within PNAPC. Obtained large dipole moment values showed that PNAPC is a highly polarizable complex, and the charge transfer occurs within PNAPC. Hydrogen bonding and charge transfer interactions were also displayed by small HOMO-LUMO gap and molecular electrostatic potential (MEP surface. The strong evidences that the material can be used as an efficient nonlinear optical (NLO material of PNAPC were demonstrated by considerable polarizability and hyperpolarizability values obtained at DFT levels.

  13. Research and implementation of simulation for TDICCD remote sensing in vibration of optical axis

    Science.gov (United States)

    Liu, Zhi-hong; Kang, Xiao-jun; Lin, Zhe; Song, Li

    2013-12-01

    During the exposure time, the charge transfer speed in the push-broom direction and the line-by-lines canning speed of the sensor are required to match each other strictly for a space-borne TDICCD push-broom camera. However, as attitude disturbance of satellite and vibration of camera are inevitable, it is impossible to eliminate the speed mismatch, which will make the signal of different targets overlay each other and result in a decline of image resolution. The effects of velocity mismatch will be visually observed and analyzed by simulating the degradation of image quality caused by the vibration of the optical axis, and it is significant for the evaluation of image quality and design of the image restoration algorithm. How to give a model in time domain and space domain during the imaging time is the problem needed to be solved firstly. As vibration information for simulation is usually given by a continuous curve, the pixels of original image matrix and sensor matrix are discrete, as a result, they cannot always match each other well. The effect of simulation will also be influenced by the discrete sampling in integration time. In conclusion, it is quite significant for improving simulation accuracy and efficiency to give an appropriate discrete modeling and simulation method. The paper analyses discretization schemes in time domain and space domain and presents a method to simulate the quality of image of the optical system in the vibration of the line of sight, which is based on the principle of TDICCD sensor. The gray value of pixels in sensor matrix is obtained by a weighted arithmetic, which solves the problem of pixels dismatch. The result which compared with the experiment of hardware test indicate that this simulation system performances well in accuracy and reliability.

  14. Nonlinear optics in the LP(02) higher-order mode of a fiber.

    Science.gov (United States)

    Chen, Y; Chen, Z; Wadsworth, W J; Birks, T A

    2013-07-29

    The distinct disperion properties of higher-order modes in optical fibers permit the nonlinear generation of radiation deeper into the ultraviolet than is possible with the fundamental mode. This is exploited using adiabatic, broadband mode convertors to couple light efficiently from an input fundamental mode and also to return the generated light to an output fundamental mode over a broad spectral range. For example, we generate visible and UV supercontinuum light in the LP(02) mode of a photonic crystal fiber from sub-ns pulses with a wavelength of 532 nm.

  15. Linear optical quantum computing in a single spatial mode.

    Science.gov (United States)

    Humphreys, Peter C; Metcalf, Benjamin J; Spring, Justin B; Moore, Merritt; Jin, Xian-Min; Barbieri, Marco; Kolthammer, W Steven; Walmsley, Ian A

    2013-10-11

    We present a scheme for linear optical quantum computing using time-bin-encoded qubits in a single spatial mode. We show methods for single-qubit operations and heralded controlled-phase (cphase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn [Nature (London) 409, 46 (2001)] scheme. Our protocol is suited to currently available photonic devices and ideally allows arbitrary numbers of qubits to be encoded in the same spatial mode, demonstrating the potential for time-frequency modes to dramatically increase the quantum information capacity of fixed spatial resources. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84±0.07.

  16. Optical Mode Converters Final Report CRADA No. TC-0838-94

    Energy Technology Data Exchange (ETDEWEB)

    Pocha, Michael D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Carey, Kent [Hewlett-Packard Company, Palo Alto, CA (United States). Agilent Technologies

    2017-11-09

    The information age was maturing, and photonics was emerging as a significant technology with important'national security and commercial implications at the time of the CRADA. This was largely due to the vast information carrying capacity of optical beams and the availability of cheap.and effective optical fiber waveguides to guide the light. However, a major limitation to the widespread deployment of photonic systems was the high-cost (in an economic and performance sense) associated with coupling optical power between optoelectronic waveguide devices or between a device and an optical fiber. The problem was critical in the case of single-mode waveguide devices. Mitigating these costs would be a significant and pervasive enabler of the technology for a wide variety of applications that would have crucial defense and economic impact. The partners worked together to develop optical mode size converters on silicon substrates. Silicon was chosen because of its compatibility with the required photolithographic and micromachining techniques. By choosing silicon, these techniques could enable the close coupling of high-speed, high density silicon electronic circuitry to efficient low-cost photonics. The efficient coupling of electronics and photonics technologies would be important for many information age technologies. The joint nature of this project was intended to allow HP to benefit from some unique LLNL capabilities, and LLNL would be in a position to learn from HP and enhance its value to fundamental DP missions. Although the CRADA began as a hardware development project to develop the mode converter, it evolved into a software development venture. LLNL and HP researchers examined literature, performed some preliminary calculations, and evaluated production trade-offs of several known techniques to determine the best candidates for an integrated system.

  17. Vibration energy harvesting based on integrated piezoelectric components operating in different modes.

    Science.gov (United States)

    Hu, Junhui; Jong, Januar; Zhao, Chunsheng

    2010-01-01

    To increase the vibration energy-harvesting capability of the piezoelectric generator based on a cantilever beam, we have proposed a piezoelectric generator that not only uses the strain change of piezoelectric components bonded on a cantilever beam, but also employs the weights at the tip of the cantilever beam to hit piezoelectric components located on the 2 sides of weights. A prototype of the piezoelectric generator has been fabricated and its characteristics have been measured and analyzed. The experimental results show that the piezoelectric components operating in the hit mode can substantially enhance the energy harvesting of the piezoelectric generator on a cantilever beam. Two methods are used and compared in the management of rectified output voltages from different groups of piezoelectric components. In one of them, the DC voltages from rectifiers are connected in series, and then the total DC voltage is applied to a capacitor. In another connection, the DC voltage from each group is applied to different capacitors. It is found that 22.3% of the harvested energy is wasted due to the series connection. The total output electric energy of our piezoelectric generator at nonresonance could be up to 43 nJ for one vibration excitation applied by spring, with initial vibration amplitude (0-p) of 18 mm and frequency of 18.5 Hz, when the rectified voltages from different groups of piezoelectric components are connected to their individual capacitors. In addition, the motion and impact of the weights at the tip of the cantilever beam are theoretically analyzed, which well explains the experimental phenomena and suggests the measures to improve the generator.

  18. Optimization design of high power ultrasonic circular ring radiator in coupled vibration.

    Science.gov (United States)

    Xu, Long; Lin, Shuyu; Hu, Wenxu

    2011-10-01

    This paper presents a new high power ultrasonic (HPU) radiator, which consists of a transducer, an ultrasonic horn, and a metal circular ring. Both the transducer and horn in longitudinal vibrations are used to drive a metal circular ring in a radial-axial coupled vibration. This coupled vibration cannot only generate ultrasound in both the radial and axial directions, but also focus the ultrasound inside the circular ring. Except for the radial-axial coupled vibration mode, the third longitudinal harmonic vibration mode with relative large vibration amplitude is also detected, which can be used as another operation mode. Overall, the HPU with these two vibration modes should have good potential to be applied in liquid processing, such as sonochemistry, ultrasonic cleaning, and Chinese herbal medicine extraction. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs.

    Science.gov (United States)

    Posada-Roman, Julio E; Garcia-Souto, Jose A; Poiana, Dragos A; Acedo, Pablo

    2016-11-26

    Optical frequency combs (OFC) generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG) sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz). Measurements of ultrasounds (40 kHz and 120 kHz) are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  20. Fast Interrogation of Fiber Bragg Gratings with Electro-Optical Dual Optical Frequency Combs

    Directory of Open Access Journals (Sweden)

    Julio E. Posada-Roman

    2016-11-01

    Full Text Available Optical frequency combs (OFC generated by electro-optic modulation of continuous-wave lasers provide broadband coherent sources with high power per line and independent control of line spacing and the number of lines. In addition to their application in spectroscopy, they offer flexible and optimized sources for the interrogation of other sensors based on wavelength change or wavelength filtering, such as fiber Bragg grating (FBG sensors. In this paper, a dual-OFC FBG interrogation system based on a single laser and two optical-phase modulators is presented. This architecture allows for the configuration of multimode optical source parameters such as the number of modes and their position within the reflected spectrum of the FBG. A direct read-out is obtained by mapping the optical spectrum onto the radio-frequency spectrum output of the dual-comb. This interrogation scheme is proposed for measuring fast phenomena such as vibrations and ultrasounds. Results are presented for dual-comb operation under optimized control. The optical modes are mapped onto detectable tones that are multiples of 0.5 MHz around a center radiofrequency tone (40 MHz. Measurements of ultrasounds (40 kHz and 120 kHz are demonstrated with this sensing system. Ultrasounds induce dynamic strain onto the fiber, which generates changes in the reflected Bragg wavelength and, hence, modulates the amplitude of the OFC modes within the reflected spectrum. The amplitude modulation of two counterphase tones is detected to obtain a differential measurement proportional to the ultrasound signal.

  1. Selective detection of crystalline cellulose in plant cell walls with sum-frequency-generation (SFG) vibration spectroscopy.

    Science.gov (United States)

    Barnette, Anna L; Bradley, Laura C; Veres, Brandon D; Schreiner, Edward P; Park, Yong Bum; Park, Junyeong; Park, Sunkyu; Kim, Seong H

    2011-07-11

    The selective detection of crystalline cellulose in biomass was demonstrated with sum-frequency-generation (SFG) vibration spectroscopy. SFG is a second-order nonlinear optical response from a system where the optical centrosymmetry is broken. In secondary plant cell walls that contain mostly cellulose, hemicellulose, and lignin with varying concentrations, only certain vibration modes in the crystalline cellulose structure can meet the noninversion symmetry requirements. Thus, SFG can be used to detect and analyze crystalline cellulose selectively in lignocellulosic biomass without extraction of noncellulosic species from biomass or deconvolution of amorphous spectra. The selective detection of crystalline cellulose in lignocellulosic biomass is not readily achievable with other techniques such as XRD, solid-state NMR, IR, and Raman analyses. Therefore, the SFG analysis presents a unique opportunity to reveal the cellulose crystalline structure in lignocellulosic biomass.

  2. Determination of fuel assembly vibrational modes through analysis of incore detector noise

    International Nuclear Information System (INIS)

    Johnson, R.S.

    1986-01-01

    In order to better characterize fuel assembly vibration at Duke Power Company's Oconee Nuclear Station, incore noise data were acquired an analyzed from prompt responding detectors incorporated in the Oconee 2, Cycle 7 core. Duke Power Company began actively pursuing an inhouse Neutron Noise Analysis program for routine surveillance of reactor internals vibration in 1979. Noise data has since been acquired and analyzed for twelve cycles of operation for the three Oconee units. Duke Power's Oconee Unit 2 is a Babcock and Wilcoxs pressurized water reactor with a rate thermal power of 2568MW. For Oconee 2, Cycle 7 operation, two test assemblies, each employing a string of seven axially-spaced, prompt responding hafnium detectors, were included in the final core design. Incore detector noise data were obtained during Cycle 7 at approximately 281 and 430 effective full power days (EFPD). In addition to the incore test detector signals, noise signals from the upper and lower chambers of the four excore power range detectors were recorded to aid in the analysis. The comparison of RMS signal levels for each incore detector and the phase relationships between detector locations within two test assemblies identified the first four fuel assembly bending modes associated with fixed end conditions

  3. Characterization and optimization of an ultrasonic piezo-optical ring sensor

    International Nuclear Information System (INIS)

    Frankforter, Erik; Lin, Bin; Giurgiutiu, Victor

    2016-01-01

    A resonant piezo-optical ring sensor with both piezoelectric and fiber Bragg grating (FBG) sensing elements was assessed for ultrasonic wave detection. The ring sensor is an existing device that has been shown experimentally to exhibit a number of sensing features: omnidirectionality, mode selectivity, and frequency tunability. The present study uses finite element modeling to understand these features as a means to characterize and optimize the sensor. A combined vibration-wave propagation modeling approach was used, where the vibrational modeling provided a basis for understanding sensing features, and the wave propagation modeling provided predictive power for sensor performance. The sensor features corresponded to the fundamental vibrational mode of the sensor, particularly to the base motion of this mode. The vibrational modeling was also used to guide sensor optimization, with an emphasis on the FBG and piezoelectric sensing elements. It was found that sensor symmetry and nodes of extraneous resonance modes could be exploited to provide a single-resonance response. A series of pitch-catch guided wave experiments were performed on a thin aluminum plate to assess the optimized sensor configuration. Tuning curves showed a single-frequency response to a Lamb wave and mechanical filtering away from the dominant frequency; the sensor capability for mechanical amplification of a Lamb wave and mechanical amplification of a pencil-lead-break acoustic emission event were also demonstrated. (paper)

  4. Nonplanar Tertiary Amides in Rigid Chiral Tricyclic Dilactams. Peptide Group Distortions and Vibrational Optical Activity

    Czech Academy of Sciences Publication Activity Database

    Pazderková, Markéta; Profant, V.; Hodačová, J.; Šebestík, Jaroslav; Pazderka, T.; Novotná, P.; Urbanová, M.; Šafařík, Martin; Buděšínský, Miloš; Tichý, Miloš; Bednárová, Lucie; Baumruk, V.; Maloň, Petr

    2013-01-01

    Roč. 117, č. 33 (2013), s. 9626-9642 ISSN 1520-6106 R&D Projects: GA ČR GAP205/10/1276 Institutional support: RVO:61388963 Keywords : spirodilactams * amide bond * vibrational circular dichroism * non-planarity * Raman optical activity Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.377, year: 2013

  5. Impact of acoustic airflow on intrasinus drug deposition: New insights into the vibrating mode and the optimal acoustic frequency to enhance the delivery of nebulized antibiotic.

    Science.gov (United States)

    Leclerc, Lara; Merhie, Amira El; Navarro, Laurent; Prévôt, Nathalie; Durand, Marc; Pourchez, Jérémie

    2015-10-15

    We investigated the impact of vibrating acoustic airflow, the high frequency (f≥100 Hz) and the low frequency (f≤45 Hz) sound waves, on the enhancement of intrasinus drug deposition. (81m)Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses, respectively. We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Optical property of few-mode fiber with non-uniform refractive index for cylindrical vector beam generation

    Science.gov (United States)

    Li, Hongye; Wan, Hongdan; Zhang, Zuxing; Sun, Bing; Zhang, Lin

    2016-10-01

    This paper investigates optical properties of few-mode fiber with non-uniform refractive index, namely: the few mode fiber with U-shape refractive index and the two-mode and four-mode few-mode fiber with bent radius. Finite element method is used to analyze the mode distributions based on their non-uniform refractive index. Effective mode control can be achieved through these few mode fibers to achieve vector beam generation. Finally, reflection spectra of a few-mode fiber Bragg grating are calculated theoretically and then measured under different bending conditions. Experimental results are in good accordance with the theoretical ones. These few mode fibers show potential applications in generation of cylindrical vector beam both for optical lasing and sensing systems.

  7. Enhancement of Optical Adaptive Sensing by Using a Dual-Stage Seesaw-Swivel Actuator with a Tunable Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Po-Chien Chou

    2011-05-01

    Full Text Available Technological obstacles to the use of rotary-type swing arm actuators to actuate optical pickup modules in small-form-factor (SFF disk drives stem from a hinge’s skewed actuation, subsequently inducing off-axis aberrations and deteriorating optical quality. This work describes a dual-stage seesaw-swivel actuator for optical pickup actuation. A triple-layered bimorph bender made of piezoelectric materials (PZTs is connected to the suspension of the pickup head, while the tunable vibration absorber (TVA unit is mounted on the seesaw swing arm to offer a balanced force to reduce vibrations in a focusing direction. Both PZT and TVA are designed to satisfy stable focusing operation operational requirements and compensate for the tilt angle or deformation of a disc. Finally, simulation results verify the performance of the dual-stage seesaw-swivel actuator, along with experimental procedures and parametric design optimization confirming the effectiveness of the proposed system.

  8. Small form factor optical fiber connector evaluation for harsh environments

    Science.gov (United States)

    Ott, Melanie N.; Thomes, W. Joe, Jr.; Chuska, Richard F.; Switzer, Robert; Blair, Diana E.

    2011-09-01

    For the past decade NASA programs have utilized the Diamond AVIM connector for optical fiber assemblies on space flight instrumentation. These connectors have been used in communications, sensing and LIDAR systems where repeatability and high performance are required. Recently Diamond has released a smaller form factor optical fiber connector called the "Mini-AVIM" which although more compact still includes the tight tolerances and the ratcheting feature of the heritage AVIM. NASA Goddard Space Flight Center Photonics Group in the Parts, Packaging and Assembly Technologies Office has been performing evaluations of this connector to determine how it compares to the performance of the AVIM connector and to assess its feasibility for harsh environmental applications. Vibration and thermal testing were performed on the Mini-AVIM with both multi-mode and single-mode optical fiber using insitu optical transmission monitoring. Random vibration testing was performed using typical launch condition profiles for most NASA missions but extended to 35 Grms, which is much higher than most requirements. Thermal testing was performed incrementally up to a range of -55°C to +125°C. The test results include both unjacketed fiber and cabled assembly evaluations. The data presented here indicate that the Mini-AVIM provides a viable option for small form factor applications that require a high performance optical fiber connector.

  9. Correlating the vibrational spectra of structurally related molecules: A spectroscopic measure of similarity.

    Science.gov (United States)

    Tao, Yunwen; Zou, Wenli; Cremer, Dieter; Kraka, Elfi

    2018-03-05

    Using catastrophe theory and the concept of a mutation path, an algorithm is developed that leads to the direct correlation of the normal vibrational modes of two structurally related molecules. The mutation path is defined by weighted incremental changes in mass and geometry of the molecules in question, which are successively applied to mutate a molecule into a structurally related molecule and thus continuously converting their normal vibrational spectra from one into the other. Correlation diagrams are generated that accurately relate the normal vibrational modes to each other by utilizing mode-mode overlap criteria and resolving allowed and avoided crossings of vibrational eigenstates. The limitations of normal mode correlation, however, foster the correlation of local vibrational modes, which offer a novel vibrational measure of similarity. It will be shown how this will open new avenues for chemical studies. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  10. Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

    Science.gov (United States)

    Platt, Michael; Jagodnik, John

    2011-01-01

    A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

  11. Anharmonic vibrational modes of chemisorbed H on the Rh(001) surface

    International Nuclear Information System (INIS)

    Hamann, D.R.; Feibelman, P.J.

    1988-01-01

    The potential for H atoms in the vicinity of the fourfold hollow chemisorption site on the Rh(001) surface at monolayer coverage is calculated using local-density-functional theory, and the linear-augmented-plane-wave method. The potential is found to contain important anharmonic components, one that couples parallel and perpendicular motion, and another producing azimuthal anisotropy. Variational solutions are found for the ground and low-lying excited states of H and D in this potential. The fundamental asymmetric- and symmetric-stretch H vibrational excitations are found to have energies of 67 and 92 meV. The latter agrees with recent experimental results, and higher-lying experimental modes are interpreted as mixed excitations. Comparisons are made with spring-constant models, calculated potentials for H on Ni and Pd(001), and theories of Bloch states for H on Ni

  12. Energy-saving framework for passive optical networks with ONU sleep/doze mode.

    Science.gov (United States)

    Van, Dung Pham; Valcarenghi, Luca; Dias, Maluge Pubuduni Imali; Kondepu, Koteswararao; Castoldi, Piero; Wong, Elaine

    2015-02-09

    This paper proposes an energy-saving passive optical network framework (ESPON) that aims to incorporate optical network unit (ONU) sleep/doze mode into dynamic bandwidth allocation (DBA) algorithms to reduce ONU energy consumption. In the ESPON, the optical line terminal (OLT) schedules both downstream (DS) and upstream (US) transmissions in the same slot in an online and dynamic fashion whereas the ONU enters sleep mode outside the slot. The ONU sleep time is maximized based on both DS and US traffic. Moreover, during the slot, the ONU might enter doze mode when only its transmitter is idle to further improve energy efficiency. The scheduling order of data transmission, control message exchange, sleep period, and doze period defines an energy-efficient scheme under the ESPON. Three schemes are designed and evaluated in an extensive FPGA-based evaluation. Results show that whilst all the schemes significantly save ONU energy for different evaluation scenarios, the scheduling order has great impact on their performance. In addition, the ESPON allows for a scheduling order that saves ONU energy independently of the network reach.

  13. The reform of the teaching mode of Applied Optics curriculum and analysis of teaching effect

    Science.gov (United States)

    Ning, Yu; Xu, Zhongjie; Li, Dun; Chen, Zilun; Cheng, Xiangai; Zhong, Hairong

    2017-08-01

    Military academies have two distinctive characteristics on talent training: Firstly, we must teach facing actual combat and connecting with academic frontier. Secondly, the bachelor's degree education and the military education should be balanced. The teaching mode of basic curriculum in military academies must be reformed and optimized on the basis of the traditional teaching mode, so as to ensure the high quality of teaching and provide enough guidance and help for students to support their academic burden. In this paper, our main work on "Applied Optics" teaching mode reform is introduced: First of all, we research extensively and learn fully from advanced teaching modes of the well-known universities at home and abroad, a whole design is made for the teaching mode of the core curriculum of optical engineering in our school "Applied Optics", building a new teaching mode which takes the methods of teaching basic parts as details, teaching application parts as emphases, teaching frontier parts as topics and teaching actual combat parts on site. Then combining with the questionnaire survey of students and opinions proposed by relevant experts in the teaching seminar, teaching effect and generalizability of the new teaching mode are analyzed and evaluated.

  14. Large electron transfer rate effects from the Duschinsky mixing of vibrations

    DEFF Research Database (Denmark)

    Sando, Gerald M.; Spears, Kenneth G; Hupp, Joseph T

    2001-01-01

    vibrations are very important. The Duschinsky effect arises when two electronic states have vibrational normal mode coordinate systems that are rotated and translated relative to each other. We use a conventional quantum rate model for ET, and the examples include 6-8 vibrations, where two vibrational modes...... are mixed with different amounts of coordinate rotation. The multidimensional Franck-Condon factors (FCF) are computed with standard algorithms and recently developed recursion relations. When displaced, totally symmetric modes are involved, rates with Duschinsky mixing can increase several orders...

  15. Geometric phases in astigmatic optical modes of arbitrary order

    International Nuclear Information System (INIS)

    Habraken, Steven J. M.; Nienhuis, Gerard

    2010-01-01

    The transverse spatial structure of a paraxial beam of light is fully characterized by a set of parameters that vary only slowly under free propagation. They specify bosonic ladder operators that connect modes of different orders, in analogy to the ladder operators connecting harmonic-oscillator wave functions. The parameter spaces underlying sets of higher-order modes are isomorphic to the parameter space of the ladder operators. We study the geometry of this space and the geometric phase that arises from it. This phase constitutes the ultimate generalization of the Gouy phase in paraxial wave optics. It reduces to the ordinary Gouy phase and the geometric phase of nonastigmatic optical modes with orbital angular momentum in limiting cases. We briefly discuss the well-known analogy between geometric phases and the Aharonov-Bohm effect, which provides some complementary insights into the geometric nature and origin of the generalized Gouy phase shift. Our method also applies to the quantum-mechanical description of wave packets. It allows for obtaining complete sets of normalized solutions of the Schroedinger equation. Cyclic transformations of such wave packets give rise to a phase shift, which has a geometric interpretation in terms of the other degrees of freedom involved.

  16. Vibrations of alkali metal overlayers on metal surfaces

    International Nuclear Information System (INIS)

    Rusina, G G; Eremeev, S V; Borisova, S D; Echenique, P M; Chulkov, E V; Benedek, G

    2008-01-01

    We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation

  17. Finite-mode analysis by means of intensity information in fractional optical systems

    NARCIS (Netherlands)

    Alieva, T.; Bastiaans, M.J.

    2002-01-01

    It is shown how a coherent optical signal that contains only a finite number of Hermite-Gauss modes, can be reconstructed from the knowledge of its Radon-Wigner transform -- associated with the intensity distribution in a fractional Fourier transform optical system -- at only two transversal points.

  18. Structural Characteristics of Rotate Vector Reducer Free Vibration

    Directory of Open Access Journals (Sweden)

    Chuan Chen

    2017-01-01

    Full Text Available For RV reducer widely used in robots, vibration significantly affects its performance. A lumped parameter model is developed to investigate free vibration characteristics without and with gyroscopic effects. The dynamic model considers key factors affecting vibration such as involute and cycloid gear mesh stiffness, crankshaft bending stiffness, and bearing stiffness. For both nongyroscopic and gyroscopic systems, free vibrations are examined and compared with each other. Results reveal the specific structure of vibration modes for both systems, which results from symmetry structure of RV reducer. According to vibration of the central components, vibration modes of two systems can be classified into three types, rotational, translational, and planetary component modes. Different from nongyroscopic system, the eigenvalues with gyroscopic effects are complex-valued and speed-dependent. The eigenvalue for a range of carrier speeds is obtained by numerical simulation. Divergence and flutter instability is observed at speeds adjacent to critical speeds. Furthermore, the work studies effects of key factors, which include crankshaft eccentricity and the number of pins, on eigenvalues. Finally, experiment is performed to verify the effectiveness of the dynamic model. The research of this paper is helpful for the analysis on free vibration and dynamic design of RV reducer.

  19. Few-mode fiber, splice and SDM component characterization by spatially-diverse optical vector network analysis.

    Science.gov (United States)

    Rommel, Simon; Mendinueta, José Manuel Delgado; Klaus, Werner; Sakaguchi, Jun; Olmos, Juan José Vegas; Awaji, Yoshinari; Monroy, Idelfonso Tafur; Wada, Naoya

    2017-09-18

    This paper discusses spatially diverse optical vector network analysis for space division multiplexing (SDM) component and system characterization, which is becoming essential as SDM is widely considered to increase the capacity of optical communication systems. Characterization of a 108-channel photonic lantern spatial multiplexer, coupled to a 36-core 3-mode fiber, is experimentally demonstrated, extracting the full impulse response and complex transfer function matrices as well as insertion loss (IL) and mode-dependent loss (MDL) data. Moreover, the mode-mixing behavior of fiber splices in the few-mode multi-core fiber and their impact on system IL and MDL are analyzed, finding splices to cause significant mode-mixing and to be non-negligible in system capacity analysis.

  20. Nonlinear resonance ultrasonic vibrations in Czochralski-silicon wafers

    Science.gov (United States)

    Ostapenko, S.; Tarasov, I.

    2000-04-01

    A resonance effect of generation of subharmonic acoustic vibrations is observed in as-grown, oxidized, and epitaxial silicon wafers. Ultrasonic vibrations were generated into a standard 200 mm Czochralski-silicon (Cz-Si) wafer using a circular ultrasound transducer with major frequency of the radial vibrations at about 26 kHz. By tuning frequency (f) of the transducer within a resonance curve, we observed a generation of intense f/2 subharmonic acoustic mode assigned as a "whistle." The whistle mode has a threshold amplitude behavior and narrow frequency band. The whistle is attributed to a nonlinear acoustic vibration of a silicon plate. It is demonstrated that characteristics of the whistle mode are sensitive to internal stress and can be used for quality control and in-line diagnostics of oxidized and epitaxial Cz-Si wafers.

  1. X-mode artificial optical emissions and attendant phenomena at EISCAT/Heating

    Science.gov (United States)

    Blagoveshchenskaya, Nataly; Sergienko, Tima; Rietveld, Michael; Brandstrom, Urban; Senior, Andrew; Haggstrom, Ingemar; Kosch, Michael; Borisova, Tatiana; Yeoman, Tim

    We present the experimental evidence for the formation of the artificial optical emissions induced by the X-mode powerful HF radio waves injected towards the magnetic zenith (MZ) into the high latitude F region of the ionosphere. The experiments were conducted in the course of Russian EISCAT heating campaigns in October 2012 and October 2013 at the Heating facility at Tromsø, Norway. The HF pump wave with the X-mode polarization was radiated at 7.1 or 6.2 MHz. The phased array 1, resulting in an ERP = 430 - 600 MW was used. Optical emissions at red (630 nm) and green (557 nm) lines were imaged from Tromsø site by the digital All-Sky Imager mark 2 (DASI - 2) and from a remote site at Abisco by the Auroral Large Imaging System (ALIS) in Scandinavia. The intensities of X-mode emissions at red and green lines varied between about of 150 - 1000 R and 50 - 300 R above the background respectively in different experiments. The artificial optical emissions were accompanied by very strong HF-enhanced ion lines and HF induced plasma lines from the EISCAT UHF incoherent scatter radar measurements and artificial small-scale field-aligned irregularities from CUTLASS (SuperDARN) HF coherent radar in Finland. The results obtained are discussed.

  2. Calcium fluoride whispering gallery mode optical resonator with reduced thermal sensitivity

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey

    2018-03-01

    We demonstrate a crystalline CaF2 resonator with thermal sensitivity of the optical modes approaching zero. The resonator is made by laminating a calcium fluoride layer forming an optical monolithic cavity with ceramic compensation layers. The ceramics is characterized with negative thermal expansion coefficient achievable in a certain temperature range. The thermally compensated resonator has a potential application for laser frequency stabilization.

  3. On the Theory of Coupled Modes in Optical Cavity-Waveguide Structures

    DEFF Research Database (Denmark)

    Kristensen, Philip Trøst; de Lasson, Jakob Rosenkrantz; Heuck, Mikkel

    2017-01-01

    Light propagation in systems of optical cavities coupled to waveguides can be conveniently described by a general rate equation model known as (temporal) coupled mode theory (CMT). We present an alternative derivation of the CMT for optical cavitywaveguide structures, which explicitly relies...... in the coupled systems. Practical application of the theory is illustrated using example calculations in one and two dimensions....

  4. Controlling coupled bending-twisting vibrations of anisotropic composite wing

    Science.gov (United States)

    Ryabov, Victor; Yartsev, Boris

    2018-05-01

    The paper discusses the possibility to control coupled bending-twisting vibrations of anisotropic composite wing by means of the monoclinic structures in the reinforcement of the plating. Decomposing the potential straining energy and kinetic energy of natural vibration modes into interacting and non-interacting parts, it became possible to introduce the two coefficients that integrally consider the effect of geometry and reinforcement structure upon the dynamic response parameters of the wing. The first of these coefficients describes the elastic coupling of the natural vibration modes, the second coefficient describes the inertial one. The paper describes the numerical studies showing how the orientation of considerably anisotropic CRP layers in the plating affects natural frequencies, loss factors, coefficients of elastic and inertial coupling for several lower tones of natural bending-twisting vibrations of the wing. Besides, for each vibration mode, partial values of the above mentioned dynamic response parameters were determined by means of the relationships for orthotropic structures where instead of "free" shearing modulus in the reinforcement plant, "pure" shearing modulus is used. Joint analysis of the obtained results has shown that each pair of bending-twisting vibration modes has its orientation angle ranges of the reinforcing layers where the inertial coupling caused by asymmetry of the cross-section profile with respect to the main axes of inertia decreases, down to the complete extinction, due to the generation of the elastic coupling in the plating material. These ranges are characterized by the two main features: 1) the difference in the natural frequencies of the investigated pair of bending-twisting vibration modes is the minimum and 2) natural frequencies of bending-twisting vibrations belong to a stretch restricted by corresponding partial natural frequencies of the investigated pair of vibration modes. This result is of practical importance

  5. Revealing silent vibration modes of nanomaterials by detecting anti-Stokes hyper-Raman scattering with femtosecond laser pulses.

    Science.gov (United States)

    Zeng, Jianhua; Chen, Lei; Dai, Qiaofeng; Lan, Sheng; Tie, Shaolong

    2016-01-21

    We proposed a scheme in which normal Raman scattering is coupled with hyper-Raman scattering for generating a strong anti-Stokes hyper-Raman scattering in nanomaterials by using femtosecond laser pulses. The proposal was experimentally demonstrated by using a single-layer MoS2 on a SiO2/Si substrate, a 17 nm-thick MoS2 on an Au/SiO2 substrate and a 9 nm-thick MoS2 on a SiO2-SnO2/Ag/SiO2 substrate which were confirmed to be highly efficient for second harmonic generation. A strong anti-Stokes hyper-Raman scattering was also observed in other nanomaterials possessing large second-order susceptibilities, such as silicon quantum dots self-assembled into "coffee" rings and tubular Cu-doped ZnO nanorods. In all the cases, many Raman inactive vibration modes were clearly revealed in the anti-Stokes hyper-Raman scattering. Apart from the strong anti-Stokes hyper-Raman scattering, Stokes hyper-Raman scattering with small Raman shifts was detected during the ablation process of thick MoS2 layers. It was also observed by slightly defocusing the excitation light. The detection of anti-Stokes hyper-Raman scattering may serve as a new technique for studying the Raman inactive vibration modes in nanomaterials.

  6. Synthesis, vibrational and optical properties of a new three-layered organic-inorganic perovskite (C4H9NH3)4Pb3I4Br6

    International Nuclear Information System (INIS)

    Dammak, T.; Elleuch, S.; Bougzhala, H.; Mlayah, A.; Chtourou, R.; Abid, Y.

    2009-01-01

    An organic-inorganic hybrid perovskite (C 4 H 9 NH 3 ) 4 Pb 3 I 4 Br 6 was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C 4 ) 4 Pb 3 I 4 Br 6 , crystallises in a periodic two-dimensional multilayer structure with P2 1 /a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX 6 (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm -1 frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C 4 ) 4 Pb 3 I 4 Br 6 , revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm.

  7. Vibration mitigation in J-TEXT far-infrared diagnostic systems

    International Nuclear Information System (INIS)

    Li, Q.; Chen, J.; Zhuang, G.; Wang, Z. J.; Gao, L.; Chen, W.

    2012-01-01

    Optical structure stability is an important issue for far-infrared (FIR) phase measurements. To ensure good signal quality, influence of vibration should be minimized. Mechanical amelioration and optical optimization can be taken in turn to decrease vibration's influence and ensure acceptable measurement. J-TEXT (Joint Texal Experiment Tokamak, formerly TEXT-U) has two FIR diagnostic systems: a HCN interferometer system for electron density measurement and a three-wave polarimeter-interferometer system (POLARIS) for electron density and Faraday effect measurements. All use phase detection techniques. HCN interferometer system has almost eliminated the influence of vibration after mechanical amelioration and optical optimization. POLARIS also obtained first experimental results after mechanical stability improvements and is expected to further reduce vibration's influence on Faraday angle to 0.1° after optical optimization.

  8. Quantum chemical study of agonist-receptor vibrational interactions for activation of the glutamate receptor.

    Science.gov (United States)

    Kubo, M; Odai, K; Sugimoto, T; Ito, E

    2001-06-01

    To understand the mechanism of activation of a receptor by its agonist, the excitation and relaxation processes of the vibrational states of the receptor should be examined. As a first approach to this problem, we calculated the normal vibrational modes of agonists (glutamate and kainate) and an antagonist (6-cyano-7-nitroquinoxaline-2,3-dione: CNQX) of the glutamate receptor, and then investigated the vibrational interactions between kainate and the binding site of glutamate receptor subunit GluR2 by use of a semiempirical molecular orbital method (MOPAC2000-PM3). We found that two local vibrational modes of kainate, which were also observed in glutamate but not in CNQX, interacted through hydrogen bonds with the vibrational modes of GluR2: (i) the bending vibration of the amine group of kainate, interacting with the stretching vibration of the carboxyl group of Glu705 of GluR2, and (ii) the symmetric stretching vibration of the carboxyl group of kainate, interacting with the bending vibration of the guanidinium group of Arg485. We also found collective modes with low frequency at the binding site of GluR2 in the kainate-bound state. The vibrational energy supplied by an agonist may flow from the high-frequency local modes to the low-frequency collective modes in a receptor, resulting in receptor activation.

  9. Femtosecond Mode-locked Fiber Laser at 1 μm Via Optical Microfiber Dispersion Management.

    Science.gov (United States)

    Wang, Lizhen; Xu, Peizhen; Li, Yuhang; Han, Jize; Guo, Xin; Cui, Yudong; Liu, Xueming; Tong, Limin

    2018-03-16

    Mode-locked Yb-doped fiber lasers around 1 μm are attractive for high power applications and low noise pulse train generation. Mode-locked fiber lasers working in soliton and stretched-pulse regime outperform others in terms of the laser noise characteristics, mechanical stability and easy maintenance. However, conventional optical fibers always show a normal group velocity dispersion around 1 μm, leading to the inconvenience for necessary dispersion management. Here we show that optical microfibers having a large anomalous dispersion around 1 μm can be integrated into mode-locked Yb-doped fiber lasers with ultralow insertion loss down to -0.06 dB, enabling convenient dispersion management of the laser cavity. Besides, optical microfibers could also be adopted to spectrally broaden and to dechirp the ultrashort pulses outside the laser cavity, giving rise to a pulse duration of about 110 fs. We believe that this demonstration may facilitate all-fiber format high-performance ultrashort pulse generation at 1 μm and may find applications in precision measurements, large-scale facility synchronization and evanescent-field-based optical sensing.

  10. System Detects Vibrational Instabilities

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1990-01-01

    Sustained vibrations at two critical frequencies trigger diagnostic response or shutdown. Vibration-analyzing electronic system detects instabilities of combustion in rocket engine. Controls pulse-mode firing of engine and identifies vibrations above threshold amplitude at 5.9 and/or 12kHz. Adapted to other detection and/or control schemes involving simultaneous real-time detection of signals above or below preset amplitudes at two or more specified frequencies. Potential applications include rotating machinery and encoders and decoders in security systems.

  11. Influence of the vibration source location on the modes of jet disintegration in the priller and on monodispersity of the finished product

    OpenAIRE

    Skydanenko, Maksym; Kononenko, Mykola; Kurdes, Yuliia

    2017-01-01

    Influence of the vibration source location on the modes of liquid jets disintegration and obtaining monodisperse droplets and granules of the finished product is theoretically grounded and experimentally confirmed. The experiment was conducted on an experimental stand of industrial granulation equipment.

  12. Mode-selective mapping and control of vectorial nonlinear-optical processes in multimode photonic-crystal fibers.

    Science.gov (United States)

    Hu, Ming-Lie; Wang, Ching-Yue; Song, You-Jian; Li, Yan-Feng; Chai, Lu; Serebryannikov, Evgenii; Zheltikov, Aleksei

    2006-02-06

    We demonstrate an experimental technique that allows a mapping of vectorial nonlinear-optical processes in multimode photonic-crystal fibers (PCFs). Spatial and polarization modes of PCFs are selectively excited in this technique by varying the tilt angle of the input beam and rotating the polarization of the input field. Intensity spectra of the PCF output plotted as a function of the input field power and polarization then yield mode-resolved maps of nonlinear-optical interactions in multimode PCFs, facilitating the analysis and control of nonlinear-optical transformations of ultrashort laser pulses in such fibers.

  13. Three-mode coupling interference patterns in the dynamic structure factor of a relaxor ferroelectric

    Science.gov (United States)

    Manley, M. E.; Abernathy, D. L.; Sahul, R.; Stonaha, P. J.; Budai, J. D.

    2016-09-01

    A longstanding controversy for relaxor ferroelectrics has been the origin of the "waterfall" effect in the phonon dispersion curves, in which low-energy transverse phonons cascade into vertical columns. Originally interpreted as phonons interacting with polar nanoregions (PNRs), it was later explained as an interference effect of coupling damped optic and acoustic phonons. In light of a recently discovered PNR vibrational mode near the "waterfall" wave vector [M. E. Manley, J. W. Lynn, D. L. Abernathy, E. D. Specht, O. Delaire, A. R. Bishop, R. Sahul, and J. D. Budai, Nat. Commun. 5, 3683 (2014), 10.1038/ncomms4683], we have reexamined this feature using neutron scattering on [100]-poled PMN-30%PT [0.6 Pb (M g1 /3N b2 /3 ) O3-0.3 PbTi O3] . We find that the PNR mode couples to both optic and acoustic phonons and that this results in complex patterns in the dynamic structure factor, including intensity pockets and peaks localized in momentum-energy space. These features are fully explained by extending the mode-coupling model to include three coupled damped harmonic oscillators representing the transverse optic, acoustic, and PNR modes.

  14. Rapid 3D µ-printing of polymer optical whispering-gallery mode resonators.

    Science.gov (United States)

    Wu, Jushuai; Guo, Xin; Zhang, A Ping; Tam, Hwa-Yaw

    2015-11-16

    A novel microfabrication method for rapid printing of polymer optical whispering-gallery mode (WGM) resonators is presented. A 3D micro-printing technology based on high-speed optical spatial modulator (SLM) and high-power UV light source is developed to fabricate suspended-disk WGM resonator array using SU-8 photoresist. The optical spectral responses of the fabricated polymer WGM resonators were measured with a biconically tapered optical fiber. Experimental results reveal that the demonstrated method is very flexible and time-saving for rapid fabrication of complex polymer WGM resonators.

  15. Ring-shaped active mode-locked tunable laser using quantum-dot semiconductor optical amplifier

    Science.gov (United States)

    Zhang, Mingxiao; Wang, Yongjun; Liu, Xinyu

    2018-03-01

    In this paper, a lot of simulations has been done for ring-shaped active mode-locked lasers with quantum-dot semiconductor optical amplifier (QD-SOA). Based on the simulation model of QD-SOA, we discussed about the influence towards mode-locked waveform frequency and pulse caused by QD-SOA maximum mode peak gain, active layer loss coefficient, bias current, incident light pulse, fiber nonlinear coefficient. In the meantime, we also take the tunable performance of the laser into consideration. Results showed QD-SOA a better performance than original semiconductor optical amplifier (SOA) in recovery time, line width, and nonlinear coefficients, which makes it possible to output a locked-mode impulse that has a higher impulse power, narrower impulse width as well as the phase is more easily controlled. After a lot of simulations, this laser can realize a 20GHz better locked-mode output pulse after 200 loops, where the power is above 17.5mW, impulse width is less than 2.7ps, moreover, the tunable wavelength range is between 1540nm-1580nm.

  16. Research on the equivalent circuit model of a circular flexural-vibration-research on the equivalent circuit model of a circular flexural-vibration-mode piezoelectric transformer with moderate thickness.

    Science.gov (United States)

    Huang, Yihua; Huang, Wenjin; Wang, Qinglei; Su, Xujian

    2013-07-01

    The equivalent circuit model of a piezoelectric transformer is useful in designing and optimizing the related driving circuits. Based on previous work, an equivalent circuit model for a circular flexural-vibration-mode piezoelectric transformer with moderate thickness is proposed and validated by finite element analysis. The input impedance, voltage gain, and efficiency of the transformer are determined through computation. The basic behaviors of the transformer are shown by numerical results.

  17. Quasi-optical internal mode converters for 110 GHz gyrotrons

    International Nuclear Information System (INIS)

    Harper, B.M.; Lorbeck, J.A.; Vernon, R.J.

    1995-01-01

    Many early gyrotrons had a microwave output in the same mode that was produced in the microwave cavity, e.g. the TE 02 mode. These modes were often converted outside of the tube to a more desirable mode for plasma heating using a system of perturbed-wall waveguide mode converters. The current generation of gyrotrons commonly have cavity modes with a high azimuthal index, such as the rotating TE 22,6 mode. Mode conversion by means of waveguide mode converters is not usually practical for such cases. However, an output of a Gaussian beam or other desirable field pattern can be obtained by using a Vlasov-type launcher feeding a series of two or more reflectors. This system may be placed outside or inside of the gyrotron but there are advantages to placing it within the tube, e.g. allowing for a larger collector and smaller reflectors. When such a converter system is placed inside the gyrotron, it is usually preferable to use a modification to the simple Vlasov launcher such as the Denisov-type launcher, which incorporates a series of perturbations within it. The authors have designed both internal and external versions of such quasi-optical converters. They discuss an internal converter which was designed for use inside of a Varian 110 GHz gyrotron producing the TE 22,6 cavity mode. This design consists of four reflectors which are fed by a Denisov-type launcher. Design techniques for the reflector system are discussed and experimental results are presented

  18. Research on Experiment-Guidance-Theory teaching mode in optics course

    Science.gov (United States)

    Lai, Jiancheng; Li, Zhenhua; Ji, Yunjing; Qi, Jing; Song, Yang

    2017-08-01

    Optical theories were all originating from the experimental phenomena, as a result, we can combine the theories and experiments organically in optics teaching that can make the teaching content more intuitive and vivid to stimulate the students' learning interests. In this paper, we proposed the "Experiment-Guidance-Theory" teaching mode in optics course by integrating the theory of optics courses with corresponding experiments. Before the theoretical learning, the students would do some basic experiments to observe the optical phenomena on themselves and answer the corresponding illuminating questions to put themselves into the role, and then the teachers explain the corresponding optical methods and theories, at last, the students must attend an expansive discussion and innovation experiment around the optical theme to expand their scientific view and innovation ability. This is a kind of inquiry-based teaching method, which can stimulate the students' studying interests and improve learning initiative. Meanwhile, the ideas of scientific research also be integrated into teaching, which is beneficial to cultivate students' ability to carry out innovative research.

  19. External modes in quantum dot light emitting diode with filtered optical feedback

    International Nuclear Information System (INIS)

    Al Husseini, Hussein B.; Al Naimee, Kais A.; Al-Khursan, Amin H.; Khedir, Ali. H.

    2016-01-01

    This research reports a theoretical investigation on the role of filtered optical feedback (FOF) in the quantum dot light emitting diode (QD-LED). The underlying dynamics is affected by a sidle node, which returns to an elliptical shape when the wetting layer (WL) is neglected. Both filter width and time delay change the appearance of different dynamics (chaotic and mixed mode oscillations, MMOs). The results agree with the experimental observations. Here, the fixed point analysis for QDs was done for the first time. For QD-LED with FOF, the system transits from the coherence collapse case in conventional optical feedback to a coherent case with a filtered mode in FOF. It was found that the WL washes out the modes which is an unexpected result. This may attributed to the longer capture time of WL compared with that between QD states. Thus, WL reduces the chaotic behavior.

  20. Optical-cell model based on the lasing competition of mode structures with different Q-factors in high-power semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Podoskin, A. A., E-mail: podoskin@mail.ioffe.ru; Shashkin, I. S.; Slipchenko, S. O.; Pikhtin, N. A.; Tarasov, I. S. [Russian Academy of Sciences, Ioffe Institute (Russian Federation)

    2015-08-15

    A model describing the operation of a completely optical cell, based on the competition of lasing of Fabry-Perot cavity modes and the high-Q closed mode in high-power semiconductor lasers is proposed. Based on rate equations, the conditions of lasing switching between Fabry-Perot modes for ground and excited lasing levels and the closed mode are considered in the case of increasing internal optical loss under conditions of high current pump levels. The optical-cell operation conditions in the mode of a high-power laser radiation switch (reversible mode-structure switching) and in the mode of a memory cell with bistable irreversible lasing switching between mode structures with various Q-factors are considered.

  1. Structural, vibrational spectroscopic and nonlinear optical activity studies on 2-hydroxy- 3, 5-dinitropyridine: A DFT approach

    Science.gov (United States)

    Asath, R. Mohamed; Premkumar, S.; Jawahar, A.; Mathavan, T.; Dhas, M. Kumara; Benial, A. Milton Franklin

    2015-06-01

    The conformational analysis was carried out for 2-Hydroxy- 3, 5-dinitropyridine molecule using potential energy surface scan and the most stable optimized conformer was predicted. The vibrational frequencies and Mulliken atomic charge distribution were calculated for the optimized geometry of the molecule using DFT/B3LYP cc-pVQZ basis set by Gaussian 09 Program. The vibrational frequencies were assigned on the basis of potential energy distribution calculation using VEDA 4.0 program. In the Frontier molecular orbitals analysis, the molecular reactivity, kinetic stability, intramolecular charge transfer studies and the calculation of ionization energy, electron affinity, global hardness, chemical potential, electrophilicity index and softness values of the title molecule were carried out. The nonlinear optical activity of the molecule was studied by means of first order hyperpolarizability, which was computed as 7.64 times greater than urea. The natural bond orbital analysis was performed to confirm the nonlinear optical activity of the molecule.

  2. Optical defect modes in chiral liquid crystals

    International Nuclear Information System (INIS)

    Belyakov, V. A.; Semenov, S. V.

    2011-01-01

    An analytic approach to the theory of optical defect modes in chiral liquid crystals (CLCs) is developed. The analytic study is facilitated by the choice of the problem parameters. Specifically, an isotropic layer (with the dielectric susceptibility equal to the average CLC dielectric susceptibility) sandwiched between two CLC layers is studied. The chosen model allows eliminating the polarization mixing and reducing the corresponding equations to the equations for light of diffracting polarization only. The dispersion equation relating the defect mode (DM) frequency to the isotropic layer thickness and an analytic expression for the field distribution in the DM structure are obtained and the corresponding dependences are plotted for some values of the DM structure parameters. Analytic expressions for the transmission and reflection coefficients of the DM structure (CLC-defect layer-CLC) are presented and analyzed for nonabsorbing, absorbing, and amplifying CLCs. The anomalously strong light absorption effect at the DM frequency is revealed. The limit case of infinitely thick CLC layers is considered in detail. It is shown that for distributed feedback lasing in a defect structure, adjusting the lasing frequency to the DM frequency results in a significant decrease in the lasing threshold. The DM dispersion equations are solved numerically for typical values of the relevant parameters. Our approach helps clarify the physics of the optical DMs in CLCs and completely agrees with the corresponding results of the previous numerical investigations.

  3. Comparison of coupled mode theory and FDTD simulations of coupling between bent and straight optical waveguides

    NARCIS (Netherlands)

    Bertolotti, M.; Symes, W.W.; Stoffer, Remco; Hiremath, K.R.; Driessen, A.; Michelotti, F; Hammer, Manfred

    Analysis of integrated optical cylindrical microresonators involves the coupling between a straight waveguide and a bent waveguide. Our (2D) variant of coupled mode theory is based on analytically represented mode profiles. With the bend modes expressed in Cartesian coordinates, coupled mode

  4. Continuous-variable quantum cloning of coherent states with phase-conjugate input modes using linear optics

    International Nuclear Information System (INIS)

    Chen, Haixia; Zhang, Jing

    2007-01-01

    We propose a scheme for continuous-variable quantum cloning of coherent states with phase-conjugate input modes using linear optics. The quantum cloning machine yields M identical optimal clones from N replicas of a coherent state and N replicas of its phase conjugate. This scheme can be straightforwardly implemented with the setups accessible at present since its optical implementation only employs simple linear optical elements and homodyne detection. Compared with the original scheme for continuous-variable quantum cloning with phase-conjugate input modes proposed by Cerf and Iblisdir [Phys. Rev. Lett. 87, 247903 (2001)], which utilized a nondegenerate optical parametric amplifier, our scheme loses the output of phase-conjugate clones and is regarded as irreversible quantum cloning

  5. A Study on the Transversal Optical Mode in Amorphous Gallium Arsenide

    OpenAIRE

    Grado-Caffaro, M. A.; Grado-Caffaro, M.

    1998-01-01

    Contributions to the far-infrared spectrum corresponding to both dynamical and structural disorders in a-GaAs are examined when frequency coincides with the transversal optical mode. Under these circumstances, dipole moment matrix element is discussed.

  6. Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

    Science.gov (United States)

    Subhash, Hrebesh M.; Choudhury, Niloy; Jacques, Steven L.; Wang, Ruikang K.; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.

    2012-01-01

    Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from each of the delay-encoded vibration images with a noise floor of ~0.3nm at 200Hz.

  7. A hydrostatic leak test for water pipeline by using distributed optical fiber vibration sensing system

    Science.gov (United States)

    Wu, Huijuan; Sun, Zhenshi; Qian, Ya; Zhang, Tao; Rao, Yunjiang

    2015-07-01

    A hydrostatic leak test for water pipeline with a distributed optical fiber vibration sensing (DOVS) system based on the phase-sensitive OTDR technology is studied in this paper. By monitoring one end of a common communication optical fiber cable, which is laid in the inner wall of the pipe, we can detect and locate the water leakages easily. Different apertures under different pressures are tested and it shows that the DOVS has good responses when the aperture is equal or larger than 4 mm and the inner pressure reaches 0.2 Mpa for a steel pipe with DN 91cm×EN 2cm.

  8. Effects of {gamma} and neutron irradiation on the optical absorption of pure silica core single-mode optical fibres from Nufern

    Energy Technology Data Exchange (ETDEWEB)

    Calderon, A. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Martinez-Rivero, C. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Matorras, F. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Rodrigo, T. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Vila, I. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Virto, A.L. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Alberdi, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Arce, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Barcala, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Calvo, E. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Ferrando, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain)]. E-mail: Antonio.Ferrando@ciemat.es; Josa, M.I. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Luque, J.M. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Molinero, A. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Navarrete, J. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Oller, J.C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Valdivieso, P. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Yuste, C. [CIEMAT, Particle Physics, Avda. Complutense 22, 28040, Madrid (Spain); Fenyvesi, A. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary); Molnar, J. [Institute of Nuclear Research, ATOMKI, Debrecen (Hungary)

    2006-09-15

    A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2x10{sup 14} cm{sup -2} and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm.

  9. Effects of γ and neutron irradiation on the optical absorption of pure silica core single-mode optical fibres from Nufern

    International Nuclear Information System (INIS)

    Calderon, A.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Sobron, M.; Vila, I.; Virto, A.L.; Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Valdivieso, P.; Yuste, C.; Fenyvesi, A.; Molnar, J.

    2006-01-01

    A measurement of the optical absorption, induced by photon irradiation up to a dose of 0.9 MGy, in Nufern silica core single-mode optical fibres is presented. In addition, the fibres were irradiated with neutrons, up to a total fluence of 2x10 14 cm -2 and the induced optical absorption was evaluated for four different wavelengths: 630, 670, 681 and 785 nm

  10. Coherent vibrational dynamics

    CERN Document Server

    Lanzani, Guglielmo; De Silvestri, Sandro

    2007-01-01

    Vibrational spectroscopy is a powerful investigation tool for a wide class of materials covering diverse areas in physics, chemistry and biology. The continuous development in the laser field regarding ultrashort pulse generation has led to the possibility of producing light pulses that can follow vibrational motion coupled to the electronic transitions in molecules and solids in real time. Aimed at researchers and graduate students using vibrational spectroscopy, this book provides both introductory chapters as well as more advanced contents reporting on recent progress. It also provides a good starting point for scientists seeking a sound introduction to ultrafast optics and spectroscopic techniques.

  11. Anomalous vibrational properties in the continuum limit of glasses

    Science.gov (United States)

    Shimada, Masanari; Mizuno, Hideyuki; Ikeda, Atsushi

    2018-02-01

    The low-temperature thermal properties of glasses are anomalous with respect to those of crystals. These thermal anomalies indicate that the low-frequency vibrational properties of glasses differ from those of crystals. Recent studies revealed that, in the simplest model of glasses, i.e., the harmonic potential system, phonon modes coexist with soft localized modes in the low-frequency (continuum) limit. However, the nature of low-frequency vibrational modes of more realistic models is still controversial. In the present work, we study the Lennard-Jones (LJ) system using large-scale molecular-dynamics (MD) simulation and establish that the vibrational property of the LJ glass converges to coexistence of the phonon modes and the soft localized modes in the continuum limit as in the case of the harmonic potential system. Importantly, we find that the low-frequency vibrations are rather sensitive to the numerical scheme of potential truncation, which is usually implemented in the MD simulation, and this is the reason why contradictory arguments have been reported by previous works. We also discuss the physical origin of this sensitiveness by means of a linear stability analysis.

  12. Various vibration modes in a silicon ring resonator driven by p–n diode actuators formed in the lateral direction

    Science.gov (United States)

    Tsushima, Takafumi; Asahi, Yoichi; Tanigawa, Hiroshi; Furutsuka, Takashi; Suzuki, Kenichiro

    2018-06-01

    In this paper, we describe p–n diode actuators that are formed in the lateral direction on resonators. Because previously reported p–n diode actuators, which were driven by a force parallel to the electrostatic force induced in a p–n diode, were fabricated in the perpendicular direction to the surface, the fabrication process to satisfy the requirement of realizing a p–n junction set in the middle of the plate thickness has been difficult. The resonators in this work are driven by p–n diodes formed in the lateral direction, making the process easy. We have fabricated a silicon ring resonator that has in-plane vibration using p–n–p and n–p–n diode actuators formed in the lateral direction. First, we consider a space charge model that can sufficiently accurately describe the force induced in p–n diode actuators and compare it with the capacitance model used in most computer simulations. Then, we show that multiplying the vibration amplitude calculated by computer simulation by the modification coefficient of 4/3 provides the vibration amplitude in the p–n diode actuators. Good agreement of the theory with experimental results of the in-plane vibration measured for silicon ring resonators is obtained. The computer simulation is very useful for evaluating various vibration modes in resonators driven by the p–n diode actuators. The small amplitude of the p–n diode actuator measured in this work is expected to increase greatly with increased doping of the actuator.

  13. High-Throughput Block Optical DNA Sequence Identification.

    Science.gov (United States)

    Sagar, Dodderi Manjunatha; Korshoj, Lee Erik; Hanson, Katrina Bethany; Chowdhury, Partha Pratim; Otoupal, Peter Britton; Chatterjee, Anushree; Nagpal, Prashant

    2018-01-01

    Optical techniques for molecular diagnostics or DNA sequencing generally rely on small molecule fluorescent labels, which utilize light with a wavelength of several hundred nanometers for detection. Developing a label-free optical DNA sequencing technique will require nanoscale focusing of light, a high-throughput and multiplexed identification method, and a data compression technique to rapidly identify sequences and analyze genomic heterogeneity for big datasets. Such a method should identify characteristic molecular vibrations using optical spectroscopy, especially in the "fingerprinting region" from ≈400-1400 cm -1 . Here, surface-enhanced Raman spectroscopy is used to demonstrate label-free identification of DNA nucleobases with multiplexed 3D plasmonic nanofocusing. While nanometer-scale mode volumes prevent identification of single nucleobases within a DNA sequence, the block optical technique can identify A, T, G, and C content in DNA k-mers. The content of each nucleotide in a DNA block can be a unique and high-throughput method for identifying sequences, genes, and other biomarkers as an alternative to single-letter sequencing. Additionally, coupling two complementary vibrational spectroscopy techniques (infrared and Raman) can improve block characterization. These results pave the way for developing a novel, high-throughput block optical sequencing method with lossy genomic data compression using k-mer identification from multiplexed optical data acquisition. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Transverse intrinsic localized modes in monatomic chain and in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Hizhnyakov, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Klopov, M. [Department of Physics, Faculty of Science, Tallinn University of Technology, Ehitajate 5, 19086 Tallinn (Estonia); Shelkan, A., E-mail: shell@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

    2016-03-06

    In this paper an analytical and numerical study of anharmonic vibrations of monatomic chain and graphene in transverse (perpendicular) with respect to the chain/plane direction is presented. Due to the lack of odd anharmonicities and presence of hard quartic anharmonicity for displacements in this direction, there may exist localized anharmonic transverse modes with the frequencies above the spectrum of the corresponding phonons. Although these frequencies are in resonance with longitudinal (chain) or in-plane (graphene) phonons, the modes can decay only due to a weak anharmonic process. Therefore the lifetime of these vibrations may be very long. E.g. in the chain, according to our theoretical and numerical calculations it may exceed 10{sup 10} periods. We call these vibrations as transverse intrinsic localized modes. - Highlights: • In a stretched monatomic chain, long-living nonlinear transverse localized modes may exist. • Transverse vibrations of a chain slowly decay due to creation of longitudinal phonons. • Lifetime of transverse vibrations of a chain may exceed billion periods of vibrations. • In stretched graphene, long-living out-of-plain localized vibrations may exist.

  15. Imaging vibration of the cochlear partition of an excised guinea pig cochlea using phase-sensitive Fourier domain optical coherence tomography

    Science.gov (United States)

    Choudhury, Niloy; Zeng, Yaguang; Fridberger, Anders; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.; Wang, Ruikang K.

    2011-03-01

    Studying the sound stimulated vibrations of various membranes that form the complex structure of the organ of Corti in the cochlea of the inner ear is essential for understanding how the travelling sound wave of the basilar membrane couples its energy to the organ structures. In this paper we report the feasibility of using phase-sensitive Fourier domain optical coherence tomography (FD-OCT) to image the vibration of various micro-structures of the cochlea at the same time. An excised cochlea of a guinea pig was stimulated using sounds at various frequencies and vibration image was obtained. When measuring the apex area, vibration signal from different turns, which have different best response frequencies are obtained in the same image. The method has the potential to measure the response from a much wider region of the cochlea than any other currently used method. The noise floor for vibration image for the system at 200 Hz was ~0.3nm.

  16. Low power excitation of gyrotron-type modes in cylindrical waveguide using quasi-optical techniques

    International Nuclear Information System (INIS)

    Alexandrov, N.L.; Whaley, D.R.; Tran, M.Q.; Denisov, D.R.

    1995-03-01

    Experimental results of low power excitation of a 118 GHz TE 22,6 rotating mode are presented. A rectangular mode is converted to a TE 22,6 circular waveguide using quasi-optical techniques. A good conversion efficiency is measured and the experimentally observed field intensity profiles show the percentage of unwanted modes to be small. (author) 10 figs., 10 refs

  17. Axisymmetric vibrations of thin shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kikuchi, Norio; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    The problem of free vibration of axisymmetric shells of revolution is important in connection with the design of pressure vessels, chemical equipment, aircrafts, structures and so on. In this study, the axisymmetrical vibration of a thin shell of revolution having a constant curvature in meridian direction was analyzed by thin shell theory. First, the Lagrangian during one period of the vibration of a shell of revolution was determined by the primary approximate theory of Love, and the vibration equations and boundary conditions were derived from its stopping condition. The vibration equations were strictly analyzed by using the series solution. The basic equations for the strain and strain energy of a shell were based on those of Novozhilov. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. The theory and the numerical calculation ore described. Especially in the frequency curves, the waving phenomena were observed frequently, which were not seen in non-axisymmetric vibration, accordingly also the vibration mode changed in complex state on the frequency curves of same order. The numerical calculation was carried out in the large computer center in Tohoku University. (Kako, I.)

  18. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  19. Low power wide spectrum optical transmitter using avalanche mode LEDs in SOI CMOS technology

    NARCIS (Netherlands)

    Agarwal, V.; Dutta, S; Annema, AJ; Hueting, RJE; Steeneken, P.G.; Nauta, B

    2017-01-01

    This paper presents a low power monolithically integrated optical transmitter with avalanche mode light emitting diodes in a 140 nm silicon-on-insulator CMOS technology. Avalanche mode LEDs in silicon exhibit wide-spectrum electroluminescence (400 nm < λ < 850 nm), which has a significant

  20. Single Mode Optical Fiber based Refractive Index Sensor using Etched Cladding

    OpenAIRE

    Kumar, Ajay; Gupta, Geeta; Mallik, Arun; Bhatnagar, Anuj

    2011-01-01

    The use of optical fiber for sensor applications is a topic of current interest. We report the fabrication of etched single mode optical fiber based refractive index sensor. Experiments are performed to determine the etch rate of fiber in buffered hydrofluoric acid, which can be high or low depending upon the temperature at which etching is carried out. Controlled wet etching of fiber cladding is performed using these measurements and etched fiber region is tested for refractive index sensing...

  1. Fundamental kinetics and innovative applications of nonequilibrium atomic vibration in thermal energy transport and conversion

    Science.gov (United States)

    Shin, Seungha

    All energy conversion inefficiencies begin with emission of resonant atomic motions, e.g., vibrations, and are declared as waste heat once these motions thermalize to equilibrium. The nonequilibrium energy occupancy of the vibrational modes can be targeted as a harvestable, low entropy energy source for direct conversion to electric energy. Since the lifetime of these resonant vibrations is short, special nanostructures are required with the appropriate tuning of the kinetics. These in turn require multiscale, multiphysics treatments. Atomic vibration is described with quasiparticle phonon in solid, and the optical phonon emission is dominant relaxation channel in semiconductors. These optical modes become over-occupied when their emission rate becomes larger than their decay rate, thus hindering energy relaxation and transport in devices. Effective removal of these phonons by drifting electrons is investigated by manipulating the electron distribution to have higher population in the low-energy states, thus allowing favorable phonon absorption. This is done through introduction, design and analysis of a heterobarrier conducting current, where the band gap is controlled by alloying, thus creating a spatial variation which is abrupt followed by a linear gradient (to ensure directed current). Self-consistent ensemble Monte Carlo simulations based on interaction kinetics between electron and phonon show that up to 19% of the phonon energy is converted to electric potential with an optimized GaAs/AlxGa1-xAs barrier structure over a range of current and electron densities, and this system is also verified through statistical entropy analysis. This direct energy conversion improves the device performance with lower operation temperature and enhances overall energy conversion efficiency. Through this study, the paradigm for harvesting the resonant atomic vibration is proposed, reversing the general role of phonon as only causing electric potential drop. Fundamentals

  2. Similarity-transformed equation-of-motion vibrational coupled-cluster theory

    Science.gov (United States)

    Faucheaux, Jacob A.; Nooijen, Marcel; Hirata, So

    2018-02-01

    A similarity-transformed equation-of-motion vibrational coupled-cluster (STEOM-XVCC) method is introduced as a one-mode theory with an effective vibrational Hamiltonian, which is similarity transformed twice so that its lower-order operators are dressed with higher-order anharmonic effects. The first transformation uses an exponential excitation operator, defining the equation-of-motion vibrational coupled-cluster (EOM-XVCC) method, and the second uses an exponential excitation-deexcitation operator. From diagonalization of this doubly similarity-transformed Hamiltonian in the small one-mode excitation space, the method simultaneously computes accurate anharmonic vibrational frequencies of all fundamentals, which have unique significance in vibrational analyses. We establish a diagrammatic method of deriving the working equations of STEOM-XVCC and prove their connectedness and thus size-consistency as well as the exact equality of its frequencies with the corresponding roots of EOM-XVCC. We furthermore elucidate the similarities and differences between electronic and vibrational STEOM methods and between STEOM-XVCC and vibrational many-body Green's function theory based on the Dyson equation, which is also an anharmonic one-mode theory. The latter comparison inspires three approximate STEOM-XVCC methods utilizing the common approximations made in the Dyson equation: the diagonal approximation, a perturbative expansion of the Dyson self-energy, and the frequency-independent approximation. The STEOM-XVCC method including up to the simultaneous four-mode excitation operator in a quartic force field and its three approximate variants are formulated and implemented in computer codes with the aid of computer algebra, and they are applied to small test cases with varied degrees of anharmonicity.

  3. Coordenadas cartesianas moleculares a partir da geometria dos modos normais de vibração Molecular cartesian coordinates from vibrational normal modes geometry

    Directory of Open Access Journals (Sweden)

    Emílio Borges

    2007-04-01

    Full Text Available A simple method to obtain molecular Cartesian coordinates as a function of vibrational normal modes is presented in this work. The method does not require the definition of special matrices, like the F and G of Wilson, neither of group theory. The Eckart's conditions together with the diagonalization of kinetic and potential energy are the only required expressions. This makes the present approach appropriate to be used as a preliminary study for more advanced concepts concerning vibrational analysis. Examples are given for diatomic and triatomic molecules.

  4. Predicting footbridge vibrations using a probability-based approach

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2017-01-01

    Vibrations in footbridges may be problematic as excessive vibrations may occur as a result of actions of pedestrians. Design-stage predictions of levels of footbridge vibration to the action of a pedestrian are useful and have been employed for many years based on a deterministic approach to mode...

  5. Sub-micrometre accurate free-form optics by three-dimensional printing on single-mode fibres

    Science.gov (United States)

    Gissibl, Timo; Thiele, Simon; Herkommer, Alois; Giessen, Harald

    2016-01-01

    Micro-optics are widely used in numerous applications, such as beam shaping, collimation, focusing and imaging. We use femtosecond 3D printing to manufacture free-form micro-optical elements. Our method gives sub-micrometre accuracy so that direct manufacturing even on single-mode fibres is possible. We demonstrate the potential of our method by writing different collimation optics, toric lenses, free-form surfaces with polynomials of up to 10th order for intensity beam shaping, as well as chiral photonic crystals for circular polarization filtering, all aligned onto the core of the single-mode fibres. We determine the accuracy of our optics by analysing the output patterns as well as interferometrically characterizing the surfaces. We find excellent agreement with numerical calculations. 3D printing of microoptics can achieve sufficient performance that will allow for rapid prototyping and production of beam-shaping and imaging devices. PMID:27339700

  6. The Study of Vibration Processes in Oil Flooded Screw Compressors

    Directory of Open Access Journals (Sweden)

    I. V. Filippov

    2014-01-01

    Full Text Available Vibration processes that accompany most of machines and mechanisms are of interest to the researcher, as a source of information about the technical condition and the nature of the business processes flow. Vibration-based diagnostics of oil flooded screw compressors allows us to estimate the deviation of their operation from the main mode in accordance with changing the settings of vibration processes.The oil flooded screw compressor transition from the main mode of operation to the abnormal one is accompanied by complex gas-dynamic phenomena i.e. the initial gaps and their decays. This leads to changes in the nature of vibration processes, prompting suggestions that there is a relationship to a change of vibration parameters and mode of compressor operation.Studies were conducted by combined method using an analytical calculation of the decay parameters of the initial discontinuity and an experimental one based on the measurement of acceleration on the body of the real oil flooded screw compressor. A virtually adequate reaction of the decay parameters of the initial gap and the peak values of vibration acceleration to the change of operation mode of oil flooded screw compressor has been received. The peak value of the vibration acceleration was selected by the method of Gating being time-coinciding with the beginning discharge phase of the oil flooded screw compressor, and therefore, with the decay time of the initial discontinuity.This indicates a large degree of hypothesis likelihood on an existing initial break in oil flooded screw compressor when operating in abnormal conditions. This work contains the study results of vibration processes and their relationship to the operating mode of the oil flooded screw compressor, which distinguish it from the other works studied vibration processes in reciprocating compressors. The vibration parameters control of operating oil flooded screw compressor allows us to create an automatic capacity control

  7. A New Fuzzy Sliding Mode Controller with a Disturbance Estimator for Robust Vibration Control of a Semi-Active Vehicle Suspension System

    Directory of Open Access Journals (Sweden)

    Byung-Keun Song

    2017-10-01

    Full Text Available This paper presents a new fuzzy sliding mode controller (FSMC to improve control performances in the presence of uncertainties related to model errors and external disturbance (UAD. As a first step, an adaptive control law is designed using Lyapunov stability analysis. The control law can update control parameters of the FSMC with a disturbance estimator (DE in which the closed-loop stability and finite-time convergence of tracking error are guaranteed. A solution for estimating the compensative quantity of the impact of UAD on a control system and a set of solutions are then presented in order to avoid the singular cases of the fuzzy-based function approximation, increase convergence ability, and reduce the calculating cost. Subsequently, the effectiveness of the proposed controller is verified through the investigation of vibration control performances of a semi-active vehicle suspension system featuring a magnetorheological damper (MRD. It is shown that the proposed controller can provide better control ability of vibration control with lower consumed power compared with two existing fuzzy sliding mode controllers.

  8. A 380pW Dual Mode Optical Wake-up Receiver with Ambient Noise Cancellation.

    Science.gov (United States)

    Lim, Wootaek; Jang, Taekwang; Lee, Inhee; Kim, Hun-Seok; Sylvester, Dennis; Blaauw, David

    2016-06-01

    We present a sub-nW optical wake-up receiver for wireless sensor nodes. The wake-up receiver supports dual mode operation for both ultra-low standby power and high data rates, while canceling ambient in-band noise. In 0.18µm CMOS the receiver consumes 380pW in always-on wake-up mode and 28.1µW in fast RX mode at 250kbps.

  9. Adaptive optics correction into single mode fiber for a low Earth orbiting space to ground optical communication link using the OPALS downlink.

    Science.gov (United States)

    Wright, Malcolm W; Morris, Jeffery F; Kovalik, Joseph M; Andrews, Kenneth S; Abrahamson, Matthew J; Biswas, Abhijit

    2015-12-28

    An adaptive optics (AO) testbed was integrated to the Optical PAyload for Lasercomm Science (OPALS) ground station telescope at the Optical Communications Telescope Laboratory (OCTL) as part of the free space laser communications experiment with the flight system on board the International Space Station (ISS). Atmospheric turbulence induced aberrations on the optical downlink were adaptively corrected during an overflight of the ISS so that the transmitted laser signal could be efficiently coupled into a single mode fiber continuously. A stable output Strehl ratio of around 0.6 was demonstrated along with the recovery of a 50 Mbps encoded high definition (HD) video transmission from the ISS at the output of the single mode fiber. This proof of concept demonstration validates multi-Gbps optical downlinks from fast slewing low-Earth orbiting (LEO) spacecraft to ground assets in a manner that potentially allows seamless space to ground connectivity for future high data-rates network.

  10. Vibration analysis of a hydro generator for different operating regimes

    Science.gov (United States)

    Haţiegan, C.; Pădureanu, I.; Jurcu, M.; Nedeloni, M. D.; Hamat, C. O.; Chioncel, C. P.; Trocaru, S.; Vasile, O.; Bădescu, O.; Micliuc, D.; (Filip Nedeloni, L.; Băra, A.; (Barboni Haţiegan, L.

    2017-01-01

    Based on experimental measurements, this paper presents the vibration analysis of a hydro generator that equips a Kaplan hydraulic turbine of a Hydropower plant in Romania. This analysis means vibrations measurement to different operating regimes of the hydro generator respectively before installing it and into operation, namely putting off load mode (unexcited and excited) respectively putting on load mode. By comparing, through the experimental results obtained before and after the operation of hydro aggregates are observed vibrations improvements.

  11. 850-nm hybrid fiber/free-space optical communications using orbital angular momentum modes

    DEFF Research Database (Denmark)

    Jurado-Navas, Antonio; Tatarczak, Anna; Lu, Xiaofeng

    2015-01-01

    Light beams can carry orbital angular momentum (OAM) associated to the helicity of their phasefronts. These OAM modes can be employed to encode information onto a laser beam for transmitting not only in a fiber link but also in a free-space optical (FSO) one. Regarding this latter scenario, FSO...... communications are considered as an alternative and promising mean complementing the traditional optical communications in many applications where the use of fiber cable is not justified. This next generation FSO communication systems have attracted much interest recently, and the inclusion of beams carrying OAM...... modes can be seen as an efficient solution to increase the capacity and the security in the link. In this paper, we discuss an experimental demonstration of a proposal for next generation FSO communication system where a light beam carrying different OAM modes and affected by M turbulence is coupled...

  12. Vibrational Characteristics of ring-type ultrasonic motor stator using ESPI

    International Nuclear Information System (INIS)

    Jung, Hyun Kyu; Paik, Sung Hoon; Kim, Seung Ho; Park, Ki Jun; Wang, Young Sung

    2001-01-01

    A stator of ring-type ultrasonic motor composed of the piezoelectric ceramic and the elastic metal was made to generate the travelling wave. Vibrational behavior of the stator was simulated by a finite element analysis using ATILA program and was measured by the electronic speckle pattern interferometry (ESPI) method. The resonance frequencies and vibration modes were analysed depending upon the comparison between the finite element analysis and ESPI measurement. The optimal vibration mode and frequency was estimated to be 7th resonant mode which was corresponded to the measured frequency of 39 KHz. It could be concluded that this fabricated stator can be applied for ring-type ultrasonic motor.

  13. New Method to Study the Vibrational Modes of Biomolecules in the Terahertz Range Based on a Single-Stage Raman Spectrometer.

    Science.gov (United States)

    Kalanoor, Basanth S; Ronen, Maria; Oren, Ziv; Gerber, Doron; Tischler, Yaakov R

    2017-03-31

    The low-frequency vibrational (LFV) modes of biomolecules reflect specific intramolecular and intermolecular thermally induced fluctuations that are driven by external perturbations, such as ligand binding, protein interaction, electron transfer, and enzymatic activity. Large efforts have been invested over the years to develop methods to access the LFV modes due to their importance in the studies of the mechanisms and biological functions of biomolecules. Here, we present a method to measure the LFV modes of biomolecules based on Raman spectroscopy that combines volume holographic filters with a single-stage spectrometer, to obtain high signal-to-noise-ratio spectra in short acquisition times. We show that this method enables LFV mode characterization of biomolecules even in a hydrated environment. The measured spectra exhibit distinct features originating from intra- and/or intermolecular collective motion and lattice modes. The observed modes are highly sensitive to the overall structure, size, long-range order, and configuration of the molecules, as well as to their environment. Thus, the LFV Raman spectrum acts as a fingerprint of the molecular structure and conformational state of a biomolecule. The comprehensive method we present here is widely applicable, thus enabling high-throughput study of LFV modes of biomolecules.

  14. Vibration of mechanically-assembled 3D microstructures formed by compressive buckling

    Science.gov (United States)

    Wang, Heling; Ning, Xin; Li, Haibo; Luan, Haiwen; Xue, Yeguang; Yu, Xinge; Fan, Zhichao; Li, Luming; Rogers, John A.; Zhang, Yihui; Huang, Yonggang

    2018-03-01

    Micro-electromechanical systems (MEMS) that rely on structural vibrations have many important applications, ranging from oscillators and actuators, to energy harvesters and vehicles for measurement of mechanical properties. Conventional MEMS, however, mostly utilize two-dimensional (2D) vibrational modes, thereby imposing certain limitations that are not present in 3D designs (e.g., multi-directional energy harvesting). 3D vibrational micro-platforms assembled through the techniques of controlled compressive buckling are promising because of their complex 3D architectures and the ability to tune their vibrational behavior (e.g., natural frequencies and modes) by reversibly changing their dimensions by deforming their soft, elastomeric substrates. A clear understanding of such strain-dependent vibration behavior is essential for their practical applications. Here, we present a study on the linear and nonlinear vibration of such 3D mesostructures through analytical modeling, finite element analysis (FEA) and experiment. An analytical solution is obtained for the vibration mode and linear natural frequency of a buckled ribbon, indicating a mode change as the static deflection amplitude increases. The model also yields a scaling law for linear natural frequency that can be extended to general, complex 3D geometries, as validated by FEA and experiment. In the regime of nonlinear vibration, FEA suggests that an increase of amplitude of external loading represents an effective means to enhance the bandwidth. The results also uncover a reduced nonlinearity of vibration as the static deflection amplitude of the 3D structures increases. The developed analytical model can be used in the development of new 3D vibrational micro-platforms, for example, to enable simultaneous measurement of diverse mechanical properties (density, modulus, viscosity etc.) of thin films and biomaterials.

  15. Highly efficient, versatile, self-Q-switched, high-repetition-rate microchip laser generating Ince–Gaussian modes for optical trapping

    Energy Technology Data Exchange (ETDEWEB)

    Jun Dong; Yu He; Xiao Zhou; Shengchuang Bai [Department of Electronics Engineering, School of Information Science and Engineering, Xiamen, 361005 (China)

    2016-03-31

    Lasers operating in the Ince-Gaussian (IG) mode have potential applications for optical manipulation of microparticles and formation of optical vortices, as well as for optical trapping and optical tweezers. Versatile, self-Q-switched, high-peak-power, high-repetition-rate Cr, Nd:YAG microchip lasers operating in the IG mode are implemented under tilted, tightly focused laser-diode pumping. An average output power of over 2 W is obtained at an absorbed pump power of 6.4 W. The highest optical-to-optical efficiency of 33.2% is achieved at an absorbed pump power of 3.9 W. Laser pulses with a pulse energy of 7.5 μJ, pulse width of 3.5 ns and peak power of over 2 kW are obtained. A repetition rate up to 335 kHz is reached at an absorbed pump power of 5.8 W. Highly efficient, versatile, IG-mode lasers with a high repetition rate and a high peak power ensure a better flexibility in particle manipulation and optical trapping. (control of laser radiation parameters)

  16. Analysis of dual-mode lasing characteristics in a 1310-nm optically injected quantum dot distributed feedback laser

    Science.gov (United States)

    Raghunathan, R.; Olinger, J.; Hurtado, A.; Grillot, F.; Kovanis, V.; Lester, L. F.

    2015-03-01

    Recent work has shown the Quantum Dot (QD) material system to be well-suited to support dual-mode lasing. In particular, optical injection from a master laser (ML) into the residual Fabry-Perot (FP) modes of a 1310 nm Quantum Dot Distributed Feedback (QD-DFB) laser has been recently demonstrated to offer a highly reliable platform for stable dual-mode lasing operation. External controls on the ML, such as operating temperature and bias current, can be used to precisely adjust the spacing between the two lasing modes. This tunability of modeseparation is very promising for a range of applications requiring the generation of microwave, millimeter wave and terahertz signals. Considering the versatility and utility of such a scheme, it is imperative to acquire a deeper understanding of the factors that influence the dual-mode lasing process, in order to optimize performance. Toward this end, this paper seeks to further our understanding of the optically-injected dual-mode lasing mechanism. For fixed values of optical power injected into each FP residual mode and wavelength detuning, the dual-mode lasing characteristics are analyzed with regard to important system parameters such as the position and the intensity of the injected residual mode (relative to the Bragg and the other residual FP modes of the device) for two similarly-fabricated QD-DFBs. Results indicate that for dual mode lasing spaced less than 5 nm apart, the relative intensity of the injected FP mode and intracavity noise levels are critical factors in determining dual mode lasing behavior. Insight into the dual-mode lasing characteristics could provide an important design guideline for the master and QD-DFB slave laser cavities.

  17. Optothermal transport behavior in whispering gallery mode optical cavities

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, Soheil [Ming Hsieh Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California 90089 (United States); Armani, Andrea M., E-mail: armani@usc.edu [Ming Hsieh Department of Electrical Engineering-Electrophysics, University of Southern California, Los Angeles, California 90089 (United States); Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, California 90089 (United States)

    2014-08-04

    Over the past century, whispering gallery mode optical cavities have enabled numerous advances in science and engineering, such as discoveries in quantum mechanics and non-linear optics, as well as the development of optical gyroscopes and add drop filters. One reason for their widespread appeal is their ability to confine light for long periods of time, resulting in high circulating intensities. However, when sufficiently large amounts of optical power are coupled into these cavities, they begin to experience optothermal or photothermal behavior, in which the optical energy is converted into heat. Above the optothermal threshold, the resonance behavior is no longer solely defined by electromagnetics. Previous work has primarily focused on the role of the optothermal coefficient of the material in this instability. However, the physics of this optothermal behavior is significantly more complex. In the present work, we develop a predictive theory based on a generalizable analytical expression in combination with a geometry-specific COMSOL Multiphysics finite element method model. The simulation couples the optical and thermal physics components, accounting for geometry variations as well as the temporal and spatial profile of the optical field. To experimentally verify our theoretical model, the optothermal thresholds of a series of silica toroidal resonant cavities are characterized at different wavelengths (visible through near-infrared) and using different device geometries. The silica toroid offers a particularly rigorous case study for the developed optothermal model because of its complex geometrical structure which provides multiple thermal transport paths.

  18. Normal mode splitting and ground state cooling in a Fabry—Perot optical cavity and transmission line resonator

    International Nuclear Information System (INIS)

    Chen Hua-Jun; Mi Xian-Wu

    2011-01-01

    Optomechanical dynamics in two systems which are a transmission line resonator and Fabrya—Perot optical cavity via radiation—pressure are investigated by linearized quantum Langevin equation. We work in the resolved sideband regime where the oscillator resonance frequency exceeds the cavity linewidth. Normal mode splittings of the mechanical resonator as a pure result of the coupling interaction in the two optomechanical systems is studied, and we make a comparison of normal mode splitting of mechanical resonator between the two systems. In the optical cavity, the normal mode splitting of the movable mirror approaches the latest experiment very well. In addition, an approximation scheme is introduced to demonstrate the ground state cooling, and we make a comparison of cooling between the two systems dominated by two key factors, which are the initial bath temperature and the mechanical quality factor. Since both the normal mode splitting and cooling require working in the resolved sideband regime, whether the normal mode splitting influences the cooling of the mirror is considered. Considering the size of the mechanical resonator and precooling the system, the mechanical resonator in the transmission line resonator system is easier to achieve the ground state cooling than in optical cavity. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  19. Influence of the precursors in the morphology, structure, vibrational order and optical gap of nano structured Zn O

    Energy Technology Data Exchange (ETDEWEB)

    Jurado, J. F.; Londono C, A.; Jurado L, F. F.; Romero S, J. D., E-mail: jfjurado@unal.edu.co [Universidad Nacional de Colombia, Laboratorio de Propiedades Termicas Dielectricas de Compositos, A. A. 127, Manizales (Colombia)

    2014-07-01

    The synthesis of Zn O by reaction in solid state from two precursor salts (zinc acetate and zinc sulfate), presented significant differences concerning morphology, structure, vibrational order and optical gap. As well as covering in the size of the compounds, a homogeneous distribution of nanoparticles of 21±3 nm and micro stars of 1.03±0.19 μm respectively. The Zn O showed a structural phase with a vibrational state of the hexagonal type (wurtzite). The variation in the morphology due to the precursor is attributed to the disorder within of lattice, which contributes to vibrational changes and is correlated to the degrees of freedom of molecules. Measurements of UV-Vis of nanoparticles displayed a band gap (E{sub g}) lower than the one reported for the bulk material. The structural characterization of the compounds was carried out by using a X-ray Bruker D8 Advance diffractometer. The vibrational order was assessed throughout micro-Raman with a monochromatic radiation source of 473 nm). (Author)

  20. Alleviation of Buffet-Induced Vibration Using Piezoelectric Actuators

    National Research Council Canada - National Science Library

    Morgenstern, Shawn D

    2006-01-01

    .... The objective of this research was to determine the most critical natural modes of vibration for the F-16 ventral fin and design piezoelectric actuators capable of reducing buffet-induced ventral fin vibration...

  1. Vibration noise control in laser satellite communication

    Science.gov (United States)

    Saksonov, Avigdor; Shlomi, Arnon; Kopeika, Norman S.

    2001-08-01

    Laser satellite communication has become especially attractive in recent years. Because the laser beam width is narrow than in the RF or microwave range, the transmitted optical power may be significantly reduced. This leads to development of miniature communication systems with extremely low power consumption. On the other hand, the laser communication channel is very sensitive to vibrations of the optical platform. These vibrations cause angular noise in laser beam pointing, comparable to the laser beam width. As result, as significant portion of the optical power between transmitter and receiver is lost and the bit error rate is increased. Consequently, vibration noise control is a critical problem in laser satellite communication. The direction of the laser beam is corrected with a fast steering mirror (FSM). In this paper are presented two approaches for the FSM control. One is the feedback control that uses an LQG algorithm. The second is the direct feed- forward control when vibration noise is measured by three orthogonal accelerometers and drives directly the F SM. The performances of each approach are evaluated using MATLAB simulations.

  2. Diffractive optics for reduction of hot cracking in pulsed mode Nd:YAG laser welding

    DEFF Research Database (Denmark)

    Bagger, Claus; Olesen, Søren; Roos, Sven-Olov

    2001-01-01

    In order to reduce the susceptibility to hot cracking in pulsed mode laser welding of austenitic stainless steel, an optical system for reduction of the cooling rate is sought developed. Based on intensive numerical simulations, an optical system producing three focused spots is made. In a number...

  3. Signal Processing using Nonlinear Optical Eects in Single- and Few-Mode Fibers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk

    noise, loss, and pump depletion on the noise properties of parametric frequency conversion and phase-insensitive and phase-sensitive parametric amplification. An important part of realizing space-division multiplexing is the ability of optical signal processing so the second part of this thesis......-wave mixing in two-mode fibers acvi counting for six simultaneous processes is derived, and the conversion efficiency from signal to idler in the four-wave mixing processes of phase conjugation and Bragg scattering in two two-mode fibers with different phase matching properties are experimentally investigated......The stagnating increase in data transmission capacity in optical communication systems combined with the ever growing demand of transmission bandwidth is leading to an impending capacity crunch, referring to the point in time after which the available bandwidth of the individual user starts...

  4. First principles study of vibrational dynamics of ceria-titania hybrid clusters

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Abdul, E-mail: abdulmajid40@yahoo.com; Bibi, Maryam [University of Gujrat, Department of Physics (Pakistan)

    2017-04-15

    Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO{sub 2}, whereas two IR active and one Raman active modes were observed for CeO{sub 2}. The comparative analysis indicates that the hybrid cluster CeTiO{sub 4} contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO{sub 4} to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices.

  5. Phase-sensitive detection of optical resonances by using an acousto-optic modulator in the Raman - Nath diffraction mode

    International Nuclear Information System (INIS)

    Baryshev, V N; Domnin, Yu S; Kopylov, L N

    2007-01-01

    A new method for frequency control of an external cavity diode laser without direct modulation of the injection current is proposed. The Pound - Drever optical heterodyne technique or the method of frequency control by frequency-modulated sidebands, in which an acousto-optic modulator operating in the Raman - Nath diffraction mode is used as an external phase modulator, can be employed to obtain error signals upon automatic frequency locking of the diode laser to the saturated absorption resonances within the D 2 line of cesium atoms or to the optical cavity resonances. (control of laser radiation parameters)

  6. Errors in the estimation method for the rejection of vibrations in adaptive optics systems

    Science.gov (United States)

    Kania, Dariusz

    2017-06-01

    In recent years the problem of the mechanical vibrations impact in adaptive optics (AO) systems has been renewed. These signals are damped sinusoidal signals and have deleterious effect on the system. One of software solutions to reject the vibrations is an adaptive method called AVC (Adaptive Vibration Cancellation) where the procedure has three steps: estimation of perturbation parameters, estimation of the frequency response of the plant, update the reference signal to reject/minimalize the vibration. In the first step a very important problem is the estimation method. A very accurate and fast (below 10 ms) estimation method of these three parameters has been presented in several publications in recent years. The method is based on using the spectrum interpolation and MSD time windows and it can be used to estimate multifrequency signals. In this paper the estimation method is used in the AVC method to increase the system performance. There are several parameters that affect the accuracy of obtained results, e.g. CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, b - number of ADC bits, γ - damping ratio of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value for systematic error is approximately 10^-10 Hz/Hz for N = 2048 and CiR = 0.1. This paper presents equations that can used to estimate maximum systematic errors for given values of H, CiR and N before the start of the estimation process.

  7. Removing damped sinusoidal vibrations in adaptive optics systems using a DFT-based estimation method

    Science.gov (United States)

    Kania, Dariusz

    2017-06-01

    The problem of a vibrations rejection in adaptive optics systems is still present in publications. These undesirable signals emerge because of shaking the system structure, the tracking process, etc., and they usually are damped sinusoidal signals. There are some mechanical solutions to reduce the signals but they are not very effective. One of software solutions are very popular adaptive methods. An AVC (Adaptive Vibration Cancellation) method has been presented and developed in recent years. The method is based on the estimation of three vibrations parameters and values of frequency, amplitude and phase are essential to produce and adjust a proper signal to reduce or eliminate vibrations signals. This paper presents a fast (below 10 ms) and accurate estimation method of frequency, amplitude and phase of a multifrequency signal that can be used in the AVC method to increase the AO system performance. The method accuracy depends on several parameters: CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, THD, b - number of A/D converter bits in a real time system, γ - the damping ratio of the tested signal, φ - the phase of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value of systematic error for γ = 0.1%, CiR = 1.1 and N = 32 is approximately 10^-4 Hz/Hz. This paper focuses on systematic errors of and effect of the signal phase and values of γ on the results.

  8. Multi-mode optical fibers for connecting space-based spectrometers

    Science.gov (United States)

    Roberts, W. T.; Lindenmisth, C. A.; Bender, S.; Miller, E. A.; Motts, E.; Ott, M.; LaRocca, F.; Thomes, J.

    2017-11-01

    significantly smaller, less massive and less robust. Large core multi-mode optical fibers are often used to accommodate the optical connection of the two separated portions of such instrumentation. In some cases, significant throughput efficiency improvement can be realized by judiciously orienting the strands of multi-fiber cable, close-bunching them to accommodate a tight focus of the optical system on the optical side of the connection, and splaying them out linearly along a spectrometer slit on the other end. For such instrumentation to work effectively in identifying elements and molecules, and especially to produce accurate quantitative results, the spectral throughput of the optical fiber connection must be consistent over varying temperatures, over the range of motion of the optical head (and it's implied optical cable stresses), and over angle-aperture invariant of the total system. While the first two of these conditions have been demonstrated[4], spectral observations of the latter present a cause for concern, and may have an impact on future design of fiber-connected LIBS and Raman spectroscopy instruments. In short, we have observed that the shape of the spectral efficiency curve of a large multi-mode core optical fiber changes as a function of input angle.

  9. Temperature monitoring of vehicle engine exhaust gases under vibration condition using optical fibre temperature sensor systems

    International Nuclear Information System (INIS)

    Zhao, W Z; Suna, T; Grattana, K T V; Shen, Y H; Wei, C L; Al-Shamma'a, A I

    2006-01-01

    Two optical approaches, comprising and contracting both the fluorescence decay lifetime and the fibre Bragg grating (FBG) methods, were developed and evaluated for temperature monitoring of exhaust gases for use on a vehicle engine. The FBGs used in the system were written into specially designed Bi-Ge co-doped photosensitive fibres, to enable them to sustain high temperatures to over 800 0 C, which is far beyond that of FBGs written into most commercial photosensitive fibres. The sensors were subjected to a range of vibration tests, as a part of an optical exhaust monitoring network under development, and results from the test carried out are reported

  10. Mode analysis and structure parameter optimization of a novel SiGe-OI rib optical waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Feng Song; Gao Yong; Yang Yuan [Department of Electronic Engineering, Xi' an University of Technology, Xi' an 710048 (China); Feng Yuchun, E-mail: vonfs@yahoo.com.c [Key Laboratories of Optoelectronic Devices and Systems, Shenzhen University, Shenzhen 518060 (China)

    2009-08-15

    The mode of a novel SiGe-OI optical waveguide is analyzed, and its single-mode conditions are derived. The Ge content and structure parameters of SiGe-OI optical waveguides are respectively optimized. Under an operation wavelength of 1300 nm, the structures of SiGe-OI rib optical waveguides are built and analyzed with Optiwave software, and the optical field and transmission losses of the SiGe-OI rib optical waveguides are analyzed. The optimization results show that when the structure parameters H, h, W are respectively 500 nm, 250 nm, 500 nm and the Ge content is 5%, the total power loss of SiGe-OI rib waveguides is 0.3683 dB/cm considering the loss of radiation outside the waveguides and materials, which is less than the traditional value of 0.5 dB/cm. The analytical technique for SiGe-OI optical waveguides and structure parameters computed by this paper are proved to be accurate and computationally efficient compared with the beam propagation method (BPM) and the experimental results. (semiconductor devices)

  11. Mode shape and natural frequency identification for seismic analysis from background vibration

    International Nuclear Information System (INIS)

    Bhan, S.; Wozniak, Z.

    1986-10-01

    Background vibration in a CANDU plant can be used to determine the dynamic characteristics of major items of equipment, such as calandria, the fuelling machines and the primary heat transport pumps. These dynamic characteristics can then be used to verify the seismic response of the equipment which, at present, is based on theoretical models only. The feasibility and basic theory of this new approach (which uses accelerations measured at several points on a structure and does not require knowledge of the source of excitation) was established in Phase I of the study. This report is based on Phase II in which the methods of analysis developed in Phase I were improved and verified experimentally. A Fast Fourier Transform (FFT) algorithm was incorporated and an interactive curve fitting technique was developed to obtain the dynamic characteristics in the form of natural frequencies, mode shapes and damping ratios. The method is now available for use at a CANDU plant

  12. Active Control of Parametric Vibrations in Coupled Rotor-Blade Systems

    DEFF Research Database (Denmark)

    Christensen, Rene Hardam; Santos, Ilmar

    2003-01-01

    of modes. The designed control scheme is applied to a coupled rotor-blade system and dynamic responses are numerically evaluated. Such responses show that the vibrations are efficiently reduced. Frequency response diagrams demonstrate that both basis and parametric vibration modes are significantly...... the model becomes periodic-variant. In order to reduce basis as well as parametric vibrations by means of active control in such systems a time-variant control strategy has to be adopted. This paper presents a methodology for designing an active controller to reduce vibrations in a coupled rotor......-blade system. The main aim is to control blade as well as hub vibrations in such a system by means of active control with focus on reducing the parametric vibration. A periodic state feedback controller is designed by transforming the system into a linear time-invariant form. Using this a controller...

  13. Linear response properties required to simulate vibrational spectra of biomolecules in various media: (R)-phenyloxirane (A comparative theoretical and spectroscopic vibrational study)

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Jürgensen, Vibeke Würtz; Degtyarenko, I.M.

    2005-01-01

    We here present a combined VA, VCD, Raman and ROA vibrational study of phenyloxirane. We have simulated the vibrational absorption (VA), also called IR, vibrational circular dichroism (VCD), Raman scattering and Raman optical activity (ROA) intensities utilizing the density functional theory (DFT...

  14. A new method for evaluating the conformations and normal modes of macromolecule vibrations with a reduced force field. 2. Application to nonplanar distorted metal porphyrins

    Energy Technology Data Exchange (ETDEWEB)

    Unger, E.; Beck, M.; Lipski, R.J.; Dreybrodt, W.; Medforth, C.J.; Smith, K.M.; Schweitzer-Stenner, R.

    1999-11-11

    The authors have developed a novel method for molecular mechanics calculations and normal-mode analysis. It is based on symmetry of local units that constitutes the given molecule. Compared with general valence force field calculations, the number of free parameters is reduced by 40--80% in the procedure. It was found to reproduce very well the vibrational frequencies and mode compositions of aromatic compounds and porphyrins, as shown by comparison with DFT calculations. A slightly altered force field obtained from Ni(II) porphin was then used to calculate the structure and the normal modes of several meso-substituted Ni(II) porphyrins which are known to be subject to significant ruffling and/or saddling distortions. This method satisfactorily reproduces their nonplanar structure and Raman band frequencies in the natural abundance and isotopic derivative spectra. The polarization properties of bands from out-of-plane modes are in accordance with the predicted nonplanar distortions. Moreover, some of the modes below 800 cm{sup {minus}1} which appear intense in the Raman spectra contain considerable contributions from both in-plane and out-of-plane vibrations, so that the conventional mode assignments become questionable. The authors also demonstrate that the intensity and polarization of some low-frequency Raman bands can be used as a (quantitative) marker to elucidate type and magnitude of out-of-plane distortions. These were recently shown to affect heme groups of hemoglobin, myoglobin, and, in particular, of cytochrome c.

  15. Entangling optical and microwave cavity modes by means of a nanomechanical resonator

    Energy Technology Data Exchange (ETDEWEB)

    Barzanjeh, Sh. [Department of Physics, Faculty of Science, University of Isfahan, Hezar Jerib, 81746-73441 Isfahan (Iran, Islamic Republic of); School of Science and Technology, Physics Division, Universita di Camerino, I-62032 Camerino, Macerata (Italy); Vitali, D.; Tombesi, P. [School of Science and Technology, Physics Division, Universita di Camerino, I-62032 Camerino, Macerata (Italy); Milburn, G. J. [Centre for Engineered Quantum Systems, School of Physical Sciences, University of Queensland, Saint Lucia, Queensland 4072 (Australia)

    2011-10-15

    We propose a scheme that is able to generate stationary continuous-variable entanglement between an optical and a microwave cavity mode by means of their common interaction with a nanomechanical resonator. We show that when both cavities are intensely driven, one can generate bipartite entanglement between any pair of the tripartite system, and that, due to entanglement sharing, optical-microwave entanglement is efficiently generated at the expense of microwave-mechanical and optomechanical entanglement.

  16. Entangling optical and microwave cavity modes by means of a nanomechanical resonator

    International Nuclear Information System (INIS)

    Barzanjeh, Sh.; Vitali, D.; Tombesi, P.; Milburn, G. J.

    2011-01-01

    We propose a scheme that is able to generate stationary continuous-variable entanglement between an optical and a microwave cavity mode by means of their common interaction with a nanomechanical resonator. We show that when both cavities are intensely driven, one can generate bipartite entanglement between any pair of the tripartite system, and that, due to entanglement sharing, optical-microwave entanglement is efficiently generated at the expense of microwave-mechanical and optomechanical entanglement.

  17. VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING

    Institute of Scientific and Technical Information of China (English)

    LIU Demin; LIU Xiaobing

    2008-01-01

    The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.

  18. Selective probe of the morphology and local vibrations at carbon nanoasperities

    Energy Technology Data Exchange (ETDEWEB)

    Fujimori, Toshihiko; Endo, Morinobu; Kaneko, Katsumi [Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1, Wakasato, Nagano-city 380-8553 (Japan); Urita, Koki; Moriguchi, Isamu [Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki-shi, Nagasaki 852-8521 (Japan); Tomanek, David [Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824 (United States); Ohba, Tomonori [Department of Chemistry, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2012-02-14

    We introduce a way to selectively probe local vibration modes at nanostructured asperities such as tips of carbon nanohorns. Our observations benefit from signal amplification in surface-enhanced Raman scattering (SERS) at sites near a silver surface. We observe nanohorn tip vibration modes in the range 200-500 cm{sup -1}, which are obscured in regular Raman spectra. Ab initio density functional calculations assign modes in this frequency range to local vibrations at the nanohorn cap resembling the radial breathing mode of fullerenes. Careful interpretation of our SERS spectra indicates presence of caps with 5 or 6 pentagons, which are chemically the most active sites. Changes in the peak intensities and frequencies with time indicate that exposure to laser irradiation may cause structural rearrangements at the cap.

  19. Calibration of piezoelectric RL shunts with explicit residual mode correction

    DEFF Research Database (Denmark)

    Høgsberg, Jan Becker; Krenk, Steen

    2017-01-01

    Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained by an exte......Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained...... by an extension of the local piezoelectric transducer displacement by two additional terms, representing the flexibility and inertia contributions from the residual vibration modes not directly addressed by the shunt damping. This results in an augmented dynamic model for the targeted resonant vibration mode...

  20. Frequency identification of vibration signals using video camera image data.

    Science.gov (United States)

    Jeng, Yih-Nen; Wu, Chia-Hung

    2012-10-16

    This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC) can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.

  1. Frequency Identification of Vibration Signals Using Video Camera Image Data

    Directory of Open Access Journals (Sweden)

    Chia-Hung Wu

    2012-10-01

    Full Text Available This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.

  2. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  3. Study of core support barrel vibration monitoring using ex-core neutron noise analysis and fuzzy logic algorithm

    International Nuclear Information System (INIS)

    Christian, Robby; Song, Seon Ho; Kang, Hyun Gook

    2015-01-01

    The application of neutron noise analysis (NNA) to the ex-core neutron detector signal for monitoring the vibration characteristics of a reactor core support barrel (CSB) was investigated. Ex-core flux data were generated by using a nonanalog Monte Carlo neutron transport method in a simulated CSB model where the implicit capture and Russian roulette technique were utilized. First and third order beam and shell modes of CSB vibration were modeled based on parallel processing simulation. A NNA module was developed to analyze the ex-core flux data based on its time variation, normalized power spectral density, normalized cross-power spectral density, coherence, and phase differences. The data were then analyzed with a fuzzy logic module to determine the vibration characteristics. The ex-core neutron signal fluctuation was directly proportional to the CSB's vibration observed at 8Hz and15Hzin the beam mode vibration, and at 8Hz in the shell mode vibration. The coherence result between flux pairs was unity at the vibration peak frequencies. A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

  4. Spatial-mode switchable ring fiber laser based on low mode-crosstalk all-fiber mode MUX/DEMUX

    Science.gov (United States)

    Ren, Fang; Yu, Jinyi; Wang, Jianping

    2018-05-01

    We report an all-fiber ring laser that emits linearly polarized (LP) modes based on the intracavity all-fiber mode multiplexer/demultiplexer (MUX/DEMUX). Multiple LP modes in ring fiber laser are generated by taking advantage of mode MUX/DEMUX. The all-fiber mode MUX/DEMUX are composed of cascaded mode-selective couplers (MSCs). The output lasing mode of the ring fiber laser can be switched among the three lowest-order LP modes by employing combination of a mode MUX and a simple N × 1 optical switch. The slope efficiencies, optical spectra and mode profiles are measured.

  5. On the bi-dimensional variational decomposition applied to nonstationary vibration signals for rolling bearing crack detection in coal cutters

    International Nuclear Information System (INIS)

    Jiang, Yu; Li, Zhixiong; Zhang, Chao; Peng, Z; Hu, Chao

    2016-01-01

    This work aims to detect rolling bearing cracks using a variational approach. An original method that appropriately incorporates bi-dimensional variational mode decomposition (BVMD) into discriminant diffusion maps (DDM) is proposed to analyze the nonstationary vibration signals recorded from the cracked rolling bearings in coal cutters. The advantage of this variational decomposition based diffusion map (VDDM) method in comparison to the current DDM is that the intrinsic vibration mode of the crack can be filtered into a limited bandwidth in the frequency domain with an estimated central frequency, thus discarding the interference signal components in the vibration signals and significantly improving the crack detection performance. In addition, the VDDM is able to simultaneously process two-channel sensor signals to reduce information leakage. Experimental validation using rolling bearing crack vibration signals demonstrates that the VDDM separated the raw signals into four intrinsic modes, including one roller vibration mode, one roller cage vibration mode, one inner race vibration mode, and one outer race vibration mode. Hence, reliable fault features were extracted from the outer race vibration mode, and satisfactory crack identification performance was achieved. The comparison between the proposed VDDM and existing approaches indicated that the VDDM method was more efficient and reliable for crack detection in coal cutter rolling bearings. As an effective catalyst for rolling bearing crack detection, this newly proposed method is useful for practical applications. (paper)

  6. Inelastic vibrational bulk and surface losses of swift electrons in ionic nanostructures

    Science.gov (United States)

    Hohenester, Ulrich; Trügler, Andreas; Batson, Philip E.; Lagos, Maureen J.

    2018-04-01

    In a recent paper [Lagos et al., Nature (London) 543, 533 (2017), 10.1038/nature21699] we have used electron energy loss spectroscopy with sub-10 meV energy and atomic spatial resolution to map optical and acoustic, bulk and surface vibrational modes in magnesium oxide nanocubes. We found that a local dielectric description works well for the simulation of aloof geometries, similar to related work for surface plasmons and surface plasmon polaritons, while for intersecting geometries such a description fails to reproduce the rich spectral features associated with excitation of bulk acoustic and optical phonons. To account for scatterings with a finite momentum exchange, in this paper we investigate molecular and lattice dynamics simulations of bulk losses in magnesium-oxide nanocubes using a rigid-ion description and investigate the loss spectra for intersecting electron beams. From our analysis we can evaluate the capability of electron energy loss spectroscopy for the investigation of phonon modes at the nanoscale, and we discuss shortcomings of our simplified approach as well as directions for future investigations.

  7. Dissociation pathways of a single dimethyl disulfide on Cu(111): Reaction induced by simultaneous excitation of two vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Motobayashi, Kenta, E-mail: kmotobayashi@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Kim, Yousoo [Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Arafune, Ryuichi [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Ohara, Michiaki; Ueba, Hiromu; Kawai, Maki, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan)

    2014-05-21

    We present a novel reaction mechanism for a single adsorbed molecule that proceeds via simultaneous excitation of two different vibrational modes excited by inelastic tunneling electrons from a scanning tunneling microscope. Specifically, we analyze the dissociation of a single dimethyl disulfide (DMDS, (CH{sub 3}S){sub 2}) molecule on Cu(111) by using a versatile theoretical method, which permits us to simulate reaction rates as a function of sample bias voltage. The reaction is induced by the excitation of C-H stretch and S-S stretch modes by a two-electron process at low positive bias voltages. However, at increased voltages, the dissociation becomes a single-electron process that excites a combination mode of these stretches, where excitation of the C-H stretch is the energy source and excitation of the S-S stretch mode enhances the anharmonic coupling rate. A much smaller dissociation yield (few orders of magnitude) at negative bias voltages is understood in terms of the projected density of states of a single DMDS on Cu(111), which reflects resonant excitation through the molecular orbitals.

  8. Compact akinetic swept source optical coherence tomography angiography at 1060 nm supporting a wide field of view and adaptive optics imaging modes of the posterior eye.

    Science.gov (United States)

    Salas, Matthias; Augustin, Marco; Felberer, Franz; Wartak, Andreas; Laslandes, Marie; Ginner, Laurin; Niederleithner, Michael; Ensher, Jason; Minneman, Michael P; Leitgeb, Rainer A; Drexler, Wolfgang; Levecq, Xavier; Schmidt-Erfurth, Ursula; Pircher, Michael

    2018-04-01

    Imaging of the human retina with high resolution is an essential step towards improved diagnosis and treatment control. In this paper, we introduce a compact, clinically user-friendly instrument based on swept source optical coherence tomography (SS-OCT). A key feature of the system is the realization of two different operation modes. The first operation mode is similar to conventional OCT imaging and provides large field of view (FoV) images (up to 45° × 30°) of the human retina and choroid with standard resolution. The second operation mode enables it to optically zoom into regions of interest with high transverse resolution using adaptive optics (AO). The FoV of this second operation mode (AO-OCT mode) is 3.0° × 2.8° and enables the visualization of individual retinal cells such as cone photoreceptors or choriocapillaris. The OCT engine is based on an akinetic swept source at 1060 nm and provides an A-scan rate of 200 kHz. Structural as well as angiographic information can be retrieved from the retina and choroid in both operational modes. The capabilities of the prototype are demonstrated in healthy and diseased eyes.

  9. Development of IR single mode optical fibers for DARWIN-nulling interferometry

    NARCIS (Netherlands)

    Chakkalakkal Abdulla, S.M.; Cheng, L.K.; Bosch, B. van den; Dijkhuizen, N.; Nieuwland, R.A.; Gielesen, W.L.M.; Lucas, J.; Boussard-Plédel, C.; Conseil, C.; Bureau, B.; Carmo, J.P. do

    2014-01-01

    The DARWIN mission aims to detect weak infra-red emission lines from distant orbiting earth-like planets using nulling interferometry. This requires filtering of wavefront errors using single mode waveguides operating at a wavelength range of 6.5-20 μm. This article describes the optical design of

  10. Integrated optics nano-opto-fluidic sensor based on whispering gallery modes for picoliter volume refractometry

    NARCIS (Netherlands)

    Gilardi, G.; Beccherelli, R.

    2013-01-01

    We propose and numerically investigate an integrated optics refractometric nano-opto-fluidic sensor based on whispering gallery modes in sapphire microspheres. A measurand fluid is injected in a micromachined reservoir defined in between the microsphere and an optical waveguide. The wavelength shift

  11. Reverse-mode PSLC multi-plane optical see-through display for AR applications.

    Science.gov (United States)

    Liu, Shuxin; Li, Yan; Zhou, Pengcheng; Chen, Quanming; Su, Yikai

    2018-02-05

    In this paper we propose an optical see-through multi-plane display with reverse-mode polymer-stabilized liquid crystal (PSLC). Our design solves the problem of accommodation-vergence conflict with correct focus cues. In the reverse mode PSLC system, power consumption could be reduced to ~1/(N-1) of that in a normal mode system if N planes are displayed. The PSLC films fabricated in our experiment exhibit a low saturation voltage ~20 V rms , a high transparent-state transmittance (92%), and a fast switching time within 2 ms and polarization insensitivity. A proof-of-concept two-plane color display prototype and a four-plane monocolor display prototype were implemented.

  12. Theoretical approach to the phonon modes and specific heat of germanium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Trejo, A.; López-Palacios, L.; Vázquez-Medina, R.; Cruz-Irisson, M., E-mail: irisson@ipn.mx

    2014-11-15

    The phonon modes and specific heat of Ge nanowires were computed using a first principles density functional theory scheme with a generalized gradient approximation and finite-displacement supercell algorithms. The nanowires were modeled in three different directions: [001], [111], and [110], using the supercell technique. All surface dangling bonds were saturated with Hydrogen atoms. The results show that the specific heat of the GeNWs at room temperature increases as the nanowire diameter decreases, regardless the orientation due to the phonon confinement and surface passivation. Also the phonon confinement effects could be observed since the highest optical phonon modes in the Ge vibration interval shifted to a lower frequency compared to their bulk counterparts.

  13. Study of optical phonon modes of CdS nanoparticles using Raman

    Indian Academy of Sciences (India)

    In this paper we report the study of optical phonon modes of nanoparticles of CdS using Raman spectroscopy. Nanoparticle sample for the present study was synthesized through chemical precipitation technique. The CdS nanoparticles were then subjected to heat treatment at low temperature (150°C) for extended time ...

  14. A long-baseline interferometer employing single-mode fiber optics

    Science.gov (United States)

    Shaklan, Stuart

    The idea of the Fiber-Linked Optical Array Telescope proposed by Connes (1987) is to mount several small optical telescopes around the perimeter of a radio dish or other large steerable structure, couple the light into single-mode (SM) fibers, and use the fibers to coherently combine the beams at the output. This paper examines the important properties of SM fibers and then discusses the whole system in general terms, starting with the telescopes and following the light through to the detectors, along with the results of laboratory experiments evaluating the performance of SM fibers. The imaging capabilities of the array were simulated, and it was found that, using 10 telescopes on a 440-m dish, the array obtains images with resolution of the order of 2 milliarc seconds in the visible range.

  15. Advanced sensing with micro-optical whispering-gallery-mode resonators

    CERN Document Server

    Righini, Giancarlo C

    2017-01-01

    This Spotlight examines an increasingly popular class of optical sensors that comprises microresonators based on the propagation of whispering gallery modes (WGMs). Several 2D and 3D WGM microresonators have already proved their capabilities as general-purpose sensors (especially as biosensors), and they have potential applications outside of research laboratories. Topics include the fundamentals of WGM propagation, types and characterization of microresonators, microfabrication issues, categories of sensing (physical, chemical, and biological), and state of the art sensors.

  16. Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber

    Directory of Open Access Journals (Sweden)

    V. V. G. Krishna Inavalli

    2012-01-01

    Full Text Available We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.

  17. Effect of foundation flexibility on the vibrational stability of the National Ignition Facility optical system support structures

    International Nuclear Information System (INIS)

    McCallen, D.

    1997-01-01

    Alignment requirements for the National Ignition Facility (NIF) optical components will require a number of support structures which minimize the system displacements and deformations. The stringent design requirements for this facility will result in a system in which vibrations due to ambient environmental loads (e.g. foundation motion due to typical traffic loads, microseisms or nearby equipment) will have a significant, and perhaps predominant, influence on the design of the supporting structures. When considering the total deformations and displacements of the structural systems, the contribution of the foundation to the overall system flexibility must be addressed. Classical fixed-base structural analyses, which are predicated on an assumption of an infinitely rigid foundation system, neglect the influence of foundation flexibility and for the vibration regime in which the NIF structures reside, may result in significant underestimation of the system ambient vibration displacements. In the work described herein, parametric studies were performed in order to understand the potential contributions of soil-structure- interaction (SSI) to optical system displacements. Time domain finite element analyses were employed to quantify the effect of wave scattering by the mat foundation and the effects of inertial SSI due to the rocking of the massive shear wall support structures. A simplified procedure is recommended for accounting for SSI effects in the design of the special equipment structures. The simplified approach consists of applying a scale factor to displacements obtained from fixed base analyses to approximately account for the effects of soil-structure interaction and variable support input motion

  18. Comparison of beam and shell theories for the vibrations of thin turbomachinery blades

    Science.gov (United States)

    Leissa, A. W.; Ewing, M. S.

    1982-01-01

    Vibration analysis of turbomachinery blades has traditionally been carried out by means of beam theory. In recent years two-dimensional methods of blade vibration analysis have been developed, most of which utilize finite elements and tend to require considerable computation time. More recently a two-dimensional method of blade analysis has evolved which does not require finite elements and is based upon shell equations. The present investigation has the primary objective to demonstrate the accuracy and limitations of blade vibration analyses which utilize one-dimensional, beam theories. It is found that beam theory is generally inadequate to determine the free vibration frequencies and mode shapes of moderate to low aspect ratio turbomachinery blades. The shallow shell theory, by contrast, is capable of representing all the vibration modes accurately. However, the one-dimensional beam theory has an important advantage over the two-dimensional shell theory for blades and vibration modes. It uses fewer degrees of freedom, thus requiring less computer time.

  19. Normal vibrations in gallium arsenide

    International Nuclear Information System (INIS)

    Dolling, G.; Waugh, J.L.T.

    1964-01-01

    The triple axis crystal spectrometer at Chalk River has been used to observe coherent slow neutron scattering from a single crystal of pure gallium arsenide at 296 o K. The frequencies of normal modes of vibration propagating in the [ζ00], (ζζζ], and (0ζζ] crystal directions have been determined with a precision of between 1 and 2·5 per cent. A limited number of normal modes have also been studied at 95 and 184 o K. Considerable difficulty was experienced in obtaining welt resolved neutron peaks corresponding to the two non-degenerate optic modes for very small wave-vector, particularly at 296 o K. However, from a comparison of results obtained under various experimental conditions at several different points in reciprocal space, frequencies (units 10 12 c/s) for these modes (at 296 o K) have been assigned: T 8·02±0·08 and L 8·55±02. Other specific normal modes, with their measured frequencies are (a) (1,0,0): TO 7·56 ± 008, TA 2·36 ± 0·015, LO 7·22 ± 0·15, LA 6·80 ± 0·06; (b) (0·5, 0·5, 0·5): TO 7·84 ± 0·12, TA 1·86 ± 0·02, LO 7·15 ± 0·07, LA 6·26 ± 0·10; (c) (0, 0·65, 0·65): optic 8·08 ±0·13, 7·54 ± 0·12 and 6·57 ± 0·11, acoustic 5·58 ± 0·08, 3·42 · 0·06 and 2·36 ± 004. These results are generally slightly lower than the corresponding frequencies for germanium. An analysis in terms of various modifications of the dipole approximation model has been carried out. A feature of this analysis is that the charge on the gallium atom appears to be very small, about +0·04 e. The frequency distribution function has been derived from one of the force models. (author)

  20. Coagulation measurement from whole blood using vibrating optical fiber in a disposable cartridge.

    Science.gov (United States)

    Yaraş, Yusuf Samet; Gündüz, Ali Bars; Sağlam, Gökhan; Ölçer, Selim; Civitçi, Fehmi; Baris, İbrahim; Yaralioğlu, Göksenin; Urey, Hakan

    2017-11-01

    In clinics, blood coagulation time measurements are performed using mechanical measurements with blood plasma. Such measurements are challenging to do in a lab-on-a-chip (LoC) system using a small volume of whole blood. Existing LoC systems use indirect measurement principles employing optical or electrochemical methods. We developed an LoC system using mechanical measurements with a small volume of whole blood without requiring sample preparation. The measurement is performed in a microfluidic channel where two fibers are placed inline with a small gap in between. The first fiber operates near its mechanical resonance using remote magnetic actuation and immersed in the sample. The second fiber is a pick-up fiber acting as an optical sensor. The microfluidic channel is engineered innovatively such that the blood does not block the gap between the vibrating fiber and the pick-up fiber, resulting in high signal-to-noise ratio optical output. The control plasma test results matched well with the plasma manufacturer's datasheet. Activated-partial-thromboplastin-time tests were successfully performed also with human whole blood samples, and the method is proven to be effective. Simplicity of the cartridge design and cost of readily available materials enable a low-cost point-of-care device for blood coagulation measurements. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  1. Semiconductor optical amplifier-based heterodyning detection for resolving optical terahertz beat-tone signals from passively mode-locked semiconductor lasers

    International Nuclear Information System (INIS)

    Latkowski, Sylwester; Maldonado-Basilio, Ramon; Carney, Kevin; Parra-Cetina, Josue; Philippe, Severine; Landais, Pascal

    2010-01-01

    An all-optical heterodyne approach based on a room-temperature controlled semiconductor optical amplifier (SOA) for measuring the frequency and linewidth of the terahertz beat-tone signal from a passively mode-locked laser is proposed. Under the injection of two external cavity lasers, the SOA acts as a local oscillator at their detuning frequency and also as an optical frequency mixer whose inputs are the self-modulated spectrum of the device under test and the two laser beams. Frequency and linewidth of the intermediate frequency signal (and therefore, the beat-tone signal) are resolved by using a photodiode and an electrical spectrum analyzer.

  2. Allocation of spectral and spatial modes in multidimensional metro-access optical networks

    Science.gov (United States)

    Gao, Wenbo; Cvijetic, Milorad

    2018-04-01

    Introduction of spatial division multiplexing (SDM) has added a new dimension in an effort to increase optical fiber channel capacity. At the same time, it can also be explored as an advanced optical networking tool. In this paper, we have investigated the resource allocation to end-users in multidimensional networking structure with plurality of spectral and spatial modes actively deployed in different networking segments. This presents a more comprehensive method as compared to the common practice where the segments of optical network are analyzed independently since the interaction between network hierarchies is included into consideration. We explored the possible transparency from the metro/core network to the optical access network, analyzed the potential bottlenecks from the network architecture perspective, and identified an optimized network structure. In our considerations, the viability of optical grooming through the entire hierarchical all-optical network is investigated by evaluating the effective utilization and spectral efficiency of the network architecture.

  3. Intermodal resonance of vibrating suspended cables

    NARCIS (Netherlands)

    Rienstra, S.W.

    2010-01-01

    The weakly nonlinear free vibrations of a single suspended cable, or a coupled system of suspended cables, may be classified as gravity modes (no tension variations to leading order) and elasto-gravity modes (tension and vertical displacement equally important). It was found earlier [12] that the

  4. Quantum localization and protein-assisted vibrational energy flow in cofactors

    International Nuclear Information System (INIS)

    Leitner, David M

    2010-01-01

    Quantum effects influence vibrational dynamics and energy flow in biomolecules, which play a central role in biomolecule function, including control of reaction kinetics. Lifetimes of many vibrational modes of proteins and their temperature dependence, as determined by quantum golden-rule-based calculations, exhibit trends consistent with experimental observation and distinct from estimates based on classical modeling. Particularly notable are quantum coherence effects that give rise to localization of vibrational states of sizable organic molecules in the gas phase. Even when such a molecule, for instance a cofactor, is embedded in a protein, remnants of quantum localization survive that influence vibrational energy flow and its dependence on temperature. We discuss these effects on the mode-damping rates of a cofactor embedded in a protein, using the green fluorescent protein chromophore as a specific example. We find that for cofactors of this size embedded in their protein and solvent environment at room temperature a golden-rule calculation often overestimates the mode-damping rate.

  5. Dissipation enhanced vibrational sensing in an olfactory molecular switch

    International Nuclear Information System (INIS)

    Chęcińska, Agata; Heaney, Libby; Pollock, Felix A.; Nazir, Ahsan

    2015-01-01

    Motivated by a proposed olfactory mechanism based on a vibrationally activated molecular switch, we study electron transport within a donor-acceptor pair that is coupled to a vibrational mode and embedded in a surrounding environment. We derive a polaron master equation with which we study the dynamics of both the electronic and vibrational degrees of freedom beyond previously employed semiclassical (Marcus-Jortner) rate analyses. We show (i) that in the absence of explicit dissipation of the vibrational mode, the semiclassical approach is generally unable to capture the dynamics predicted by our master equation due to both its assumption of one-way (exponential) electron transfer from donor to acceptor and its neglect of the spectral details of the environment; (ii) that by additionally allowing strong dissipation to act on the odorant vibrational mode, we can recover exponential electron transfer, though typically at a rate that differs from that given by the Marcus-Jortner expression; (iii) that the ability of the molecular switch to discriminate between the presence and absence of the odorant, and its sensitivity to the odorant vibrational frequency, is enhanced significantly in this strong dissipation regime, when compared to the case without mode dissipation; and (iv) that details of the environment absent from previous Marcus-Jortner analyses can also dramatically alter the sensitivity of the molecular switch, in particular, allowing its frequency resolution to be improved. Our results thus demonstrate the constructive role dissipation can play in facilitating sensitive and selective operation in molecular switch devices, as well as the inadequacy of semiclassical rate equations in analysing such behaviour over a wide range of parameters

  6. Smart accelerometer. [vibration damage detection

    Science.gov (United States)

    Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    The invention discloses methods and apparatus for detecting vibrations from machines which indicate an impending malfunction for the purpose of preventing additional damage and allowing for an orderly shutdown or a change in mode of operation. The method and apparatus is especially suited for reliable operation in providing thruster control data concerning unstable vibration in an electrical environment which is typically noisy and in which unrecognized ground loops may exist.

  7. Vibrational Spectral Studies of Gemfibrozil

    Science.gov (United States)

    Benitta, T. Asenath; Balendiran, G. K.; James, C.

    2008-11-01

    The Fourier Transform Raman and infrared spectra of the crystallized drug molecule 5-(2,5-Dimethylphenoxy)-2,2-dimethylpentanoic acid (Gemfibrozil) have been recorded and analyzed. Quantum chemical computational methods have been employed using Gaussian 03 software package based on Hartree Fock method for theoretically modeling the grown molecule. The optimized geometry and vibrational frequencies have been predicted. Observed vibrational modes have been assigned with the aid of normal coordinate analysis.

  8. Optical sum-frequency generation in a whispering-gallery-mode resonator

    International Nuclear Information System (INIS)

    Strekalov, Dmitry V; Kowligy, Abijith S; Huang, Yu-Ping; Kumar, Prem

    2014-01-01

    We demonstrate sum-frequency generation between a telecom wavelength and the Rb D2 line, achieved through natural phase matching in a nonlinear whispering gallery mode resonator. Due to the strong optical field confinement and ultra high Q of the cavity, the process saturates already at sub-mW pump peak power, at least two orders of magnitude lower than in existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory based on spherical geometry. Our experimental and theoretical results point toward a new platform for manipulating the color and quantum states of light waves for applications such as atomic memory based quantum networking and logic operations with optical signals. (paper)

  9. Performance evaluation of a burst-mode EDFA in an optical packet and circuit integrated network.

    Science.gov (United States)

    Shiraiwa, Masaki; Awaji, Yoshinari; Furukawa, Hideaki; Shinada, Satoshi; Puttnam, Benjamin J; Wada, Naoya

    2013-12-30

    We experimentally investigate the performance of burst-mode EDFA in an optical packet and circuit integrated system. In such networks, packets and light paths can be dynamically assigned to the same fibers, resulting in gain transients in EDFAs throughout the network that can limit network performance. Here, we compare the performance of a 'burst-mode' EDFA (BM-EDFA), employing transient suppression techniques and optical feedback, with conventional EDFAs, and those using automatic gain control and previous BM-EDFA implementations. We first measure gain transients and other impairments in a simplified set-up before making frame error-rate measurements in a network demonstration.

  10. Entanglement indicators for quantum optical fields: three-mode multiport beamsplitters EPR interference experiments

    Science.gov (United States)

    Ryu, Junghee; Marciniak, Marcin; Wieśniak, Marcin; Żukowski, Marek

    2018-04-01

    We generalize a new approach to entanglement conditions for light of undefined photons numbers given in Żukowski et al (2017 Phys. Rev. A 95 042113) for polarization correlations to a broader family of interferometric phenomena. Integrated optics allows one to perform experiments based upon multiport beamsplitters. To observe entanglement effects one can use multi-mode parametric down-conversion emissions. When the structure of the Hamiltonian governing the emissions has (infinitely) many equivalent Schmidt decompositions into modes (beams), one can have perfect EPR-like correlations of numbers of photons emitted into ‘conjugate modes’ which can be monitored at spatially separated detection stations. We provide entanglement conditions for experiments involving three modes on each side, and three-input-three-output multiport beamsplitters, and show their violations by bright squeezed vacuum states. We show that a condition expressed in terms of averages of observed rates is a much better entanglement indicator than a related one for the usual intensity variables. Thus, the rates seem to emerge as a powerful concept in quantum optics, especially for fields of undefined intensities.

  11. Geometrical nonlinear free vibration of multi-layered graphene sheets

    International Nuclear Information System (INIS)

    Wang Jinbao; He Xiaoqiao; Kitipornchai, S; Zhang Hongwu

    2011-01-01

    A nonlinear continuum model is developed for the nonlinear vibration analysis of multi-layered graphene sheets (MLGSs), in which the nonlinear van der Waals (vdW) interaction between any two layers is formulated explicitly. The nonlinear equations of motion are studied by the harmonic-balance methods. Based on the present model, the nonlinear stiffened amplitude-frequency relations of double-layered graphene sheets (DLGSs) are investigated in the spectral neighbourhood of lower frequencies. The influence of the vdW interaction on the vibration properties of DLGSs is well illustrated by plotting the resulting modes' shapes, in which in-phase and anti-phase vibrations of DLGSs are studied. In particular, the large-amplitude vibration which associates with the anti-phase resonant frequencies, separating DLGS into single-layered GSs, is a promising application that needs to be explored further. In contrast, the vibration modes that are associated with the resonant frequencies are nonidentical and give various vibration patterns, which indicates that MLGSs are highly suited to being used as high-frequency resonators.

  12. Excited-state lifetimes of far-infrared collective modes in proteins

    NARCIS (Netherlands)

    Xie, A.; van der Meer, L.; Austin, R. H.

    2002-01-01

    Vibrational excitations of low frequency collective modes are essential for functionally important conformational transitions in proteins. Here we report the first direct measurement on the lifetime of vibrational excitations of the collective modes at 87 pm (115 cm(-1)) in bacteriorhodopsin, a

  13. Wannier–Stark electro-optical effect, quasi-guided and photonic modes in 2D macroporous silicon structures with SiO_2 coatings

    International Nuclear Information System (INIS)

    Karachevtseva, L.; Goltviansky, Yu.; Sapelnikova, O.; Lytvynenko, O.; Stronska, O.; Bo, Wang; Kartel, M.

    2016-01-01

    Highlights: • The IR absorption spectra of oxidized macroporous silicon were studied. • The Wannier–Stark electro-optical effect on Si-SiO_2 boundary was confirmed. • An additional electric field of quasi-guided optical modes was evaluated. • The photonic modes and band gaps were measured as peculiarities in absorption spectra. - Abstract: Opportunities to enhance the properties of structured surfaces were demonstrated on 2D macroporous silicon structures with SiO_2 coatings. We investigated the IR light absorption oscillations in macroporous silicon structures with SiO2 coatings 0–800 nm thick. The Wannier–Stark electro-optical effect due to strong electric field on Si-SiO_2boundary and an additional electric field of quasi-guided optical modes were taken into account. The photonic modes and band gaps were also considered as peculiarities in absorbance spectra of macroporous silicon structures with a thick SiO_2 coating. The photonic modes do not coincide with the quasi-guided modes in the silicon matrix and do not appear in absorption spectra of 2D macroporous silicon structures with surface nanocrystals.

  14. An optical technique to measure the frequency and mode emission of tunable lasers

    International Nuclear Information System (INIS)

    Marchetti, S.; Simili, R.

    1988-01-01

    To use mode tunable lasers it is necessary to measure the laser frequency and the mode emission. This problem is very important when waveguide lasers are used. Normally this information is obtained by a heterodyne technique, but there are some difficulties to perform this method in a large electrical noise environment, when pulsed of radiofrequency lasers are used. This laser information was obtained by using an alternative low-cost optical system. With this apparatus the cavity pulling was measured and an upper limit for the linewidth of a radiofrequency, high pressure, line and mode-tunable, CO 2 laser was roughly estimated

  15. Electrically tunable Brillouin fiber laser based on a metal-coated single-mode optical fiber

    Directory of Open Access Journals (Sweden)

    S.M. Popov

    Full Text Available We explore tunability of the Brillouin fiber laser employing Joule heating. For this purpose, 10-m-length of a metal-coated single-mode optical cavity fiber has been directly included into an electrical circuit, like a conductor wire. With the current up to ∼3.5 A the laser tuning is demonstrated over a spectrum range of ∼400 MHz. The observed laser line broadening up to ∼2 MHz is explained by frequency drift and mode-hoping in the laser caused by thermal noise. Keywords: Brillouin fiber laser, Metal-coated optical fiber, Laser tuning, Fiber sensors

  16. Integrated active sensor system for real time vibration monitoring.

    Science.gov (United States)

    Liang, Qijie; Yan, Xiaoqin; Liao, Xinqin; Cao, Shiyao; Lu, Shengnan; Zheng, Xin; Zhang, Yue

    2015-11-05

    We report a self-powered, lightweight and cost-effective active sensor system for vibration monitoring with multiplexed operation based on contact electrification between sensor and detected objects. The as-fabricated sensor matrix is capable of monitoring and mapping the vibration state of large amounts of units. The monitoring contents include: on-off state, vibration frequency and vibration amplitude of each unit. The active sensor system delivers a detection range of 0-60 Hz, high accuracy (relative error below 0.42%), long-term stability (10000 cycles). On the time dimension, the sensor can provide the vibration process memory by recording the outputs of the sensor system in an extend period of time. Besides, the developed sensor system can realize detection under contact mode and non-contact mode. Its high performance is not sensitive to the shape or the conductivity of the detected object. With these features, the active sensor system has great potential in automatic control, remote operation, surveillance and security systems.

  17. APPLICATION OF THE SPECTRUM ANALYSIS WITH USING BERG METHOD TO DEVELOPED SPECIAL SOFTWARE TOOLS FOR OPTICAL VIBRATION DIAGNOSTICS SYSTEM

    Directory of Open Access Journals (Sweden)

    E. O. Zaitsev

    2016-01-01

    Full Text Available The objective of this paper is development and experimental verification special software of spectral analysis. Spectral analysis use of controlled vibrations objects. Spectral analysis of vibration based on use maximum-entropy autoregressive method of spectral analysis by the Berg algorithm. For measured signals use preliminary analysis based on regression analysis. This analysis of the signal enables to eliminate uninformative parameters such as – the noise and the trend. For preliminary analysis developed special software tools. Non-contact measurement of mechanical vibrations parameters rotating diffusely-reflecting surfaces used in circumstances where the use of contact sensors difficult or impossible for a number of reasons, including lack of access to the object, the small size of the controlled area controlled portion has a high temperature or is affected by strong electromagnetic fields. For control use offered laser measuring system. This measuring system overcomes the shortcomings interference or Doppler optical measuring systems. Such as measure the large amplitude and inharmonious vibration. On the basis of the proposed methods developed special software tools for use measuring laser system. LabVIEW using for developed special software. Experimental research of the proposed method of vibration signals processing is checked in the analysis of the diagnostic information obtained by measuring the vibration system grinding diamond wheel cold solid tungsten-containing alloy TK8. A result of work special software tools was complex spectrum obtained «purified» from non-informative parameters. Spectrum of the signal corresponding to the vibration process observed object. 

  18. Flexible long-range surface plasmon polariton single-mode waveguide for optical interconnects

    DEFF Research Database (Denmark)

    Vernoux, Christian; Chen, Yiting; Markey, Laurent

    2018-01-01

    We present the design, fabrication and characterization of long-range surface plasmon polariton waveguide arrays with materials, mainly silicones, carefully selected with the aim to be used as mechanically flexible single-mode optical interconnections, the socalled "plasmonic arc" working at 1.55μm...

  19. Vibrational measurements in 3-ID-B

    International Nuclear Information System (INIS)

    Sutter, J.; Alp, E.; Barraza, J.; Shu, D.

    1998-04-01

    The authors have undertaken a series of vibrational measurements in hutch 3-ID-B. Their motivation was to compare two different methods of mounting an interferometer for effectiveness in vibrational isolation and stability. In addition they were able to compare the stability of the optical table with and without its eight large bolts inserted

  20. Four-plate piezoelectric actuator driving a large-diameter special optical fiber for nonlinear optical microendoscopy.

    Science.gov (United States)

    Wang, Ying; Li, Zhi; Liang, Xiaobao; Fu, Ling

    2016-08-22

    In nonlinear optical microendoscope (NOME), a fiber with excellent optical characteristics and a miniature scanning mechanism at the distal end are two key components. Double-clad fibers (DCFs) and double-clad photonic crystal fibers (DCPCFs) have shown great optical characteristics but limited vibration amplitude due to large diameter. Besides reducing the damping of fiber cantilever, optimizing the structural of the actuator for lower energy dissipation also contributes to better driving capability. This paper presented an optimized actuator for driving a particular fiber cantilever in the view point of energy. Firstly, deformation energy of a bending fiber cantilever operating in resonant mode is investigated. Secondly, strain and stress analyses revealed that the four-plate actuator achieved lower energy dissipation. Then, finite-element simulations showed that the large-diameter fiber yielded an adequate vibration amplitude driven by a four-plate actuator, which was confirmed by experiments of our home-made four-plate actuator prototypes. Additionally, a NOME based on a DCPCF with a diameter of 350 μm driven by four-plate piezoelectric actuator has been developed. The NOME can excite and collect intrinsic second-harmonic and two-photon fluorescence signals with the excitation power of 10-30 mW and an adequate field of view of 200 μm, which suggest great potential applications in neuroscience and clinical diagnoses.

  1. Vibrational spectroscopic, structural and nonlinear optical activity studies on 6-aminonicotinamide: A DFT approach

    Science.gov (United States)

    Asath, R. Mohamed; Premkumar, S.; Rekha, T. N.; Jawahar, A.; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    The conformational analysis was carried out for 6-aminonicotinamide (ANA) using potential energy surface scan method and the most stable optimized conformer was predicted. The theoretical vibrational frequencies were calculated for the optimized geometry using DFT/B3LYP cc-pVQZ basis set by Gaussian 09 Program. The vibrational frequencies were assigned on the basis of potential energy distribution calculation using VEDA 4.0 program. The Mulliken atomic charge values were calculated. In the Frontier molecular orbitals analysis, the molecular reactivity, kinetic stability, intermolecular charge transfer studies and the related molecular properties were calculated. The ultraviolet-visible spectrum was simulated for both in the gas phase and liquid phase (ethanol) and the л to л* electronic transition was predicted. The nonlinear optical (NLO) activity was studied by means of the first order hyperpolarizability value, which was 8.61 times greater than the urea and the natural bond orbital analysis was also performed to confirm the NLO activity of the molecule. Hence, the ANA molecule is a promising candidate for the NLO materials.

  2. Vibrational spectroscopic, structural and nonlinear optical activity studies on 6-aminonicotinamide: A DFT approach

    Energy Technology Data Exchange (ETDEWEB)

    Asath, R. Mohamed; Premkumar, S.; Mathavan, T.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, N.M.S.S.V.N College, Madurai-625019, Tamilnadu (India); Rekha, T. N. [PG & Research Department of Physics, Lady Doak College, Madurai 625002, Tamilnadu (India); Jawahar, A. [Department of Chemistry, N.M.S.S.V.N College, Madurai-625019, Tamilnadu (India)

    2016-05-23

    The conformational analysis was carried out for 6-aminonicotinamide (ANA) using potential energy surface scan method and the most stable optimized conformer was predicted. The theoretical vibrational frequencies were calculated for the optimized geometry using DFT/B3LYP cc-pVQZ basis set by Gaussian 09 Program. The vibrational frequencies were assigned on the basis of potential energy distribution calculation using VEDA 4.0 program. The Mulliken atomic charge values were calculated. In the Frontier molecular orbitals analysis, the molecular reactivity, kinetic stability, intermolecular charge transfer studies and the related molecular properties were calculated. The ultraviolet-visible spectrum was simulated for both in the gas phase and liquid phase (ethanol) and the π to π* electronic transition was predicted. The nonlinear optical (NLO) activity was studied by means of the first order hyperpolarizability value, which was 8.61 times greater than the urea and the natural bond orbital analysis was also performed to confirm the NLO activity of the molecule. Hence, the ANA molecule is a promising candidate for the NLO materials.

  3. Effect of oxygen incorporation on the vibrational properties of Al0.2Ga0.3In0.5P:Be films

    International Nuclear Information System (INIS)

    Soubervielle-Montalvo, C.; Vital-Ochoa, O.; Anda, F. de; Vazquez-Cortes, D.; Rodriguez, A.G.; Melendez-Lira, M.; Mendez-Garcia, V.H.

    2011-01-01

    The vibrational properties of Al 0.2 Ga 0.3 In 0.5 P:Be films grown on (100) GaAs substrates by solid source molecular beam epitaxy varying the phosphorous cracking-zone temperature (PCT) were studied by Raman spectroscopy. The Raman-intensity ratio between the allowed longitudinal optical and the forbidden transverse optical (TO) phonons, and the full width at half maximum of their Lorentzian fits were used to characterize the crystalline quality of the films. The Raman spectra from the samples show changes in the shape and intensity of phonon resonances depending on the PCT variation, indicating that the disorder in the lattice increases with PCT. The increasing disorder is related to the inclusion of oxygen, which act as a non-intentional perturbing impurity in the lattice. In addition, a vibrational mode located at 598 cm -1 related to a forbidden InP-like TO phonon resonance was correlated with oxygen-induced disorder. Photoluminescence at room temperature shows that the high inclusion of oxygen also deteriorates the optical properties of the samples, by introducing non-radiative recombination centers.

  4. Tapered Polymer Fiber Sensors for Reinforced Concrete Beam Vibration Detection.

    Science.gov (United States)

    Luo, Dong; Ibrahim, Zainah; Ma, Jianxun; Ismail, Zubaidah; Iseley, David Thomas

    2016-12-16

    In this study, tapered polymer fiber sensors (TPFSs) have been employed to detect the vibration of a reinforced concrete beam (RC beam). The sensing principle was based on transmission modes theory. The natural frequency of an RC beam was theoretically analyzed. Experiments were carried out with sensors mounted on the surface or embedded in the RC beam. Vibration detection results agreed well with Kistler accelerometers. The experimental results found that both the accelerometer and TPFS detected the natural frequency function of a vibrated RC beam well. The mode shapes of the RC beam were also found by using the TPFSs. The proposed vibration detection method provides a cost-comparable solution for a structural health monitoring (SHM) system in civil engineering.

  5. Modulation stability and dispersive optical soliton solutions of higher order nonlinear Schrödinger equation and its applications in mono-mode optical fibers

    Science.gov (United States)

    Arshad, Muhammad; Seadawy, Aly R.; Lu, Dianchen

    2018-01-01

    In mono-mode optical fibers, the higher order non-linear Schrödinger equation (NLSE) describes the propagation of enormously short light pulses. We constructed optical solitons and, solitary wave solutions of higher order NLSE mono-mode optical fibers via employing modified extended mapping method which has important applications in Mathematics and physics. Furthermore, the formation conditions are also given on parameters in which optical bright and dark solitons can exist for this media. The moment of the obtained solutions are also given graphically, that helps to realize the physical phenomena's of this model. The modulation instability analysis is utilized to discuss the model stability, which verifies that all obtained solutions are exact and stable. Many other such types of models arising in applied sciences can also be solved by this reliable, powerful and effective method. The method can also be functional to other sorts of higher order nonlinear problems in contemporary areas of research.

  6. Interplay of nonclassicality and entanglement of two-mode Gaussian fields generated in optical parametric processes

    Czech Academy of Sciences Publication Activity Database

    Arkhipov, Ie.I.; Peřina, Jan; Peřina, J.; Miranowicz, A.

    2016-01-01

    Roč. 94, č. 1 (2016), 1-15, č. článku 013807. ISSN 2469-9926 R&D Projects: GA ČR GAP205/12/0382 Institutional support: RVO:68378271 Keywords : two-mode Gaussian fields * optical parametric processes Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.925, year: 2016

  7. Role of Fe doping on structural and vibrational properties of ZnO nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Pandiyarajan, T.; Udayabhaskar, R.; Karthikeyan, B. [National Institute of Technology, Department of Physics, Tiruchirappalli (India)

    2012-05-15

    In this report, Raman and Fourier Transform Infrared (FTIR) measurements were carried out to study the phonon modes of pure and Fe doped ZnO nanoparticles. The nanoparticles were prepared by sol-gel technique at room temperature. The X-ray diffraction measurements reveal that the nanoparticles are in hexagonal wurtzite structure and doping makes the shrinkage of the lattice parameters, whereas there is no alteration in the unit cell. Raman measurements show both E{sub 2}{sup low} and E{sub 2}{sup High} optical phonon mode is shifted towards lower wave number with Fe incorporation and explained on the basis of force constant variation, stress measurements, respectively. In addition, Fe related local vibrational modes (LVM) were observed for higher concentration of Fe doping. FTIR spectra reveal a band at 444 cm{sup -1} which is specific to E{sub 1} (TO) mode; a red-shift of this mode in Fe doped samples and some surface phonon modes were observed. Furthermore, the observation of additional IR modes, which is considered to have an origin related to Fe dopant in the ZnO nanostructures, is also reported. These additional mode features can be regarded as an indicator for the incorporation of Fe ions into the lattice position of the ZnO nanostructures. (orig.)

  8. Determination of acoustic vibration in watermelon by finite element modeling

    Science.gov (United States)

    Nourain, Jamal; Ying, Yibin B.; Wang, Jianping; Rao, Xiuqin

    2004-11-01

    The analysis of the vibration responses of a fruit is suggested to measure firmness non-destructively. A wooden ball excited the fruits and the response signals were captured using an accelerometer sensor. The method has been well studied and understood on ellipsoidal shaped fruit (watermelon). In this work, using the finite element simulations, the applicability of the method on watermelon was investigated. The firmness index is dependent on the mass, density, and natural frequency of the lowest spherical modes (under free boundary conditions). This developed index extends the firmness estimation for fruits or vegetables from a spherical to an ellipsoidal shape. The mode of Finite element analysis (FEA) of watermelon was generated based on measured geometry, and it can be served as a theoretical reference for predicting the modal characteristics as a function of design parameters such as material, geometrical, and physical properties. It was found that there were four types of mode shapes. The 1st one was first-type longitudinal mode, the 2nd one was the second-type longitudinal mode, the 3rd one was breathing mode or pure compression mode, and the fourth was flexural or torsional mode shape. As suggested in many references, the First-type spherical vibration mode or oblate-Prolate for watermelon is the lowest bending modes, it's most likely related to fruit firmness. Comparisons of finite element and experimental modal parameters show that both results were agreed in mode shape as well as natural frequencies. In order to measure the vibration signal of the mode, excitation and sensors should be placed on the watermelon surface far away from the nodal lines. The excitation and the response sensors should be in accordance with vibration directions. The correlations between the natural frequency and firmness was 0.856, natural frequency and Young's modulus was 0.800, and the natural frequency and stiffness factor (SF) was 0.862. The stiffness factor (SF) is adequate

  9. Ultrafast fragmentation dynamics of triply charged carbon dioxide: Vibrational-mode-dependent molecular bond breakage

    Science.gov (United States)

    Yang, HongJiang; Wang, Enliang; Dong, WenXiu; Gong, Maomao; Shen, Zhenjie; Tang, Yaguo; Shan, Xu; Chen, Xiangjun

    2018-05-01

    The a b i n i t i o molecular dynamics (MD) simulations using an atom-centered density matrix propagation method have been carried out to investigate the fragmentation of the ground-state triply charged carbon dioxide, CO23 +→C+ + Oa+ + Ob+ . Ten thousands of trajectories have been simulated. By analyzing the momentum correlation of the final fragments, it is demonstrated that the sequential fragmentation dominates in the three-body dissociation, consistent with our experimental observations which were performed by electron collision at impact energy of 1500 eV. Furthermore, the MD simulations allow us to have detailed insight into the ultrafast evolution of the molecular bond breakage at a very early stage, within several tens of femtoseconds, and the result shows that the initial nuclear vibrational mode plays a decisive role in switching the dissociation pathways.

  10. Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance Actuator

    Directory of Open Access Journals (Sweden)

    José Salvado

    2017-01-01

    Full Text Available This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design.

  11. Free-vibration acoustic resonance of a nonlinear elastic bar

    Science.gov (United States)

    Tarumi, Ryuichi; Oshita, Yoshihito

    2011-02-01

    Free-vibration acoustic resonance of a one-dimensional nonlinear elastic bar was investigated by direct analysis in the calculus of variations. The Lagrangian density of the bar includes a cubic term of the deformation gradient, which is responsible for both geometric and constitutive nonlinearities. By expanding the deformation function into a complex Fourier series, we derived the action integral in an analytic form and evaluated its stationary conditions numerically with the Ritz method for the first three resonant vibration modes. This revealed that the bar shows the following prominent nonlinear features: (i) amplitude dependence of the resonance frequency; (ii) symmetry breaking in the vibration pattern; and (iii) excitation of the high-frequency mode around nodal-like points. Stability of the resonant vibrations was also addressed in terms of a convex condition on the strain energy density.

  12. Development of vibrational analysis for detection of antisymmetric shells

    International Nuclear Information System (INIS)

    Esmailzadeh Khadem, S.; Mahmoodi, M.; Rezaee, M.

    2002-01-01

    In this paper, vibrational behavior of bodies of revolution with different types of structural faults is studied. Since vibrational characteristics of structures are natural properties of system, the existence of any structural faults causes measurable changes in these properties. Here, this matter is demonstrated. In other words, vibrational behavior of a body of revolution with no structural faults is analyzed by two methods of I) numerical analysis using super sap software, II) Experimental model analysis, and natural frequencies and mode shapes are obtained. Then, different types of cracks are introduced in the structure, and analysis is repeated and the results are compared. Based on this study, one may perform crack detection by measuring the natural frequencies and mode shapes of the samples and comparing with reference information obtained from the vibration analysis of the original structure with no fault

  13. Computation of mode eigenfunctions in graded-index optical fibers by the propagating beam method

    International Nuclear Information System (INIS)

    Feit, M.D.; Fleck, J.A. Jr.

    1980-01-01

    The propagating beam method utilizes discrete Fourier transforms for generating configuration-space solutions to optical waveguide problems without reference to modes. The propagating beam method can also give a complete description of the field in terms of modes by a Fourier analysis with respect to axial distance of the computed fields. Earlier work dealt with the accurate determination of mode propagation constants and group delays. In this paper the method is extended to the computation of mode eigenfunctions. The method is efficient, allowing generation of a large number of eigenfunctions from a single propagation run. Computations for parabolic-index profiles show excellent agreement between analytic and numerically generated eigenfunctions

  14. Study of core support barrel vibration monitoring using ex-core neutron noise analysis and fuzzy logic algorithm

    Directory of Open Access Journals (Sweden)

    Robby Christian

    2015-03-01

    A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

  15. Fiber-optic seismic sensor

    International Nuclear Information System (INIS)

    Finch, G. W.; Udd, E.

    1985-01-01

    A vibration sensor is constructed by providing two preferably matched coils of fiber-optic material. When the sensor experiences vibration, a differential pressure is exerted on the two fiber coils. The differential pressure results in a variation in the relative optical path lengths between the two fibers so that light beams transmitted through the two fibers are differently delayed, the phase difference therebetween being a detectable indication of the vibration applied to the sensor

  16. Inducing spin-dependent tunneling to probe magnetic correlations in optical lattices

    DEFF Research Database (Denmark)

    Pedersen, Kim-Georg; Andersen, Brian; Syljuåsen, Olav

    2012-01-01

    We suggest a simple experimental method for probing antiferromagnetic spin correlations of two-component Fermi gases in optical lattices. The method relies on a spin selective Raman transition to excite atoms of one spin species to their first excited vibrational mode where the tunneling is large....... The resulting difference in the tunneling dynamics of the two spin species can then be exploited, to reveal the spin correlations by measuring the number of doubly occupied lattice sites at a later time. We perform quantum Monte Carlo simulations of the spin system and solve the optical lattice dynamics...

  17. The effects of an inserted linear carbon chain on the vibration of a carbon nanotube

    International Nuclear Information System (INIS)

    Hu, Z L; Guo, X M; Ru, C Q

    2007-01-01

    An elastic string-elastic shell model is developed to study the coupled vibration of a carbon nanowire made of a linear carbon chain (C-chain) inserted inside a carbon nanotube (CNT). It is shown that the vibration of the inserted C-chain is coupled with vibration of the CNT only for vibration modes with circumferential wavenumber n = 1. In other cases, such as axisymmetric modes (n = 0) or higher-order vibration modes with n≥2, total resultant van der Waals (vdW) force acting on the C-chain due to the innermost tube always vanishes, and therefore vibration of the CNT does not cause vibration of the inserted C-chain, although the existence of the C-chain does have an effect on the vibration of the CNT through the chain-CNT vdW forces acting on the innermost tube. The present model predicts that non-coaxial vibration between the C-chain and the innermost tube does not occur due to negligible bending rigidity of the C-chain. In addition, it is found that the C-chain has most significant effect on the lowest frequency associated with the radial vibration mode for circumferential wavenumber 2 (n = 2). In particular, the effect of the C-chain on the axisymmetric radial breathing frequencies (n = 0) predicted by the present model is found to be in reasonable agreement with known experimental and modeling results available in the literature. The present work offers systematic modeling results on the effects of an inserted C-chain on the vibration of CNTs

  18. Cantilever-based sensor with integrated optical read-out using single mode waveguides

    DEFF Research Database (Denmark)

    Nordström, Maria; Zauner, Dan; Calleja, Montserrat

    2007-01-01

    This work presents the design, fabrication and mechanical characterisation of an integrated optical read-out scheme for cantilever-based biosensors. A cantilever can be used as a biosensor by monitoring its bending caused by the surface stress generated due to chemical reactions occurring on its...... surface. Here, we present a novel integrated optical read-out scheme based on single-mode waveguides that enables the fabrication of a compact system. The complete system is fabricated in the polymer SU-8. This manuscript shows the principle of operation and the design well as the fabrication...

  19. Temporal mode selectivity by frequency conversion in second-order nonlinear optical waveguides

    DEFF Research Database (Denmark)

    Reddy, D. V.; Raymer, M. G.; McKinstrie, C. J.

    2013-01-01

    in a transparent optical network using temporally orthogonal waveforms to encode different channels. We model the process using coupled-mode equations appropriate for wave mixing in a uniform second-order nonlinear optical medium pumped by a strong laser pulse. We find Green functions describing the process...... in this optimal regime. We also find an operating regime in which high-efficiency frequency conversion without temporal-shape selectivity can be achieved while preserving the shapes of a wide class of input pulses. The results are applicable to both classical and quantum frequency conversion....

  20. Semiclassical Wigner distribution for a two-mode entangled state generated by an optical parametric oscillator

    International Nuclear Information System (INIS)

    Dechoum, K.; Hahn, M. D.; Khoury, A. Z.; Vallejos, R. O.

    2010-01-01

    We derive the steady-state solution of the Fokker-Planck equation that describes the dynamics of the nondegenerate optical parametric oscillator in the truncated Wigner representation of the density operator. We assume that the pump mode is strongly damped, which permits its adiabatic elimination. When the elimination is correctly executed, the resulting stochastic equations contain multiplicative noise terms and do not admit a potential solution. However, we develop a heuristic scheme leading to a satisfactory steady-state solution. This provides a clear view of the intracavity two-mode entangled state valid in all operating regimes of the optical parametric oscillator. A non-Gaussian distribution is obtained for the above threshold solution.

  1. Multi-Mode Vibration Suppression in MIMO Systems by Extending the Zero Placement Input Shaping Technique: Applications to a 3-DOF Piezoelectric Tube Actuator

    Directory of Open Access Journals (Sweden)

    Yasser Al Hamidi

    2016-04-01

    Full Text Available Piezoelectric tube actuators are extensively used in scanning probe microscopes to provide dynamic scanning motions in open-loop operations. Furthermore, they are employed as micropositioners due to their high bandwidth, high resolution and ease of excitation. However, these piezoelectric micropositioners exhibit badly damped vibrations that occur when the input excites the dynamic response, which tends to degrade positioning accuracy and performance. This paper deals with vibrations’ feedforward control of a multi-degrees of freedom (DOF piezoelectric micropositioner in order to damp the vibrations in the direct axes and to reduce the cross-couplings. The novelty in this paper relative to the existing vibrations feedforward controls is the simplicity in design approach, the minimal number of shaper impulses for each input required to damp all modes of vibration at each output, and the account for the strong cross-couplings which only occur in multi-DOF cases. A generalization to a multiple degrees of freedom actuator is first proposed. Then simulation runs on a 3-DOF piezoelectric tube micropositioner have been effectuated to demonstrate the efficiency of the proposed method. Finally, experimental tests were carried out to validate and to confirm the predicted simulation.

  2. Dispersive-cavity actively mode-locked fiber laser for stable radio frequency delivery

    International Nuclear Information System (INIS)

    Dai, Yitang; Wang, Ruixin; Yin, Feifei; Xu, Kun; Li, Jianqiang; Lin, Jintong

    2013-01-01

    We report a novel technique for highly stable transfer of a radio frequency (RF) comb over long optical fiber link, which is highly dispersive and is a part of an actively mode-locked fiber laser. Phase fluctuation along the fiber link, which is mainly induced by physical vibration and temperature fluctuations, is automatically compensated by the self-adapted wavelength shifting. Without phase-locking loop or any tunable parts, stable radio frequency is transferred over a 2-km fiber link, with a time jitter suppression ratio larger than 110. (letter)

  3. VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD

    Directory of Open Access Journals (Sweden)

    Johan Debayle

    2011-05-01

    Full Text Available An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.

  4. Vibrational Spectra and Density functional calculation of Organic Nonlinear Optic Crystal p-Amino Acetanilide

    Energy Technology Data Exchange (ETDEWEB)

    Saja, D; Joe, I Hubert; Jayakumar, V S [Department of Physics, Mar Ivanios College, Thiruvananthapuram-695015, Kerala (India)

    2006-01-01

    The NIR-FT Raman, FT-IR spectral analysis of potential NLO material P-Amino Acetanilide is carried out by density functional computations. The optimized geometry shows that NH2 and NHCOCH3 groups substituted in para position of phenyl ring are non-planar which predicts maximum conjugation of molecule with donor and acceptor groups. Vibrational analysis reveals that simultaneous IR and Raman activation of the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and the acceptor can make the molecule highly polarized and the intra molecular charge transfer interaction must be responsible for the NLO properties of PAA.

  5. Vibrational Spectra and Density functional calculation of Organic Nonlinear Optic Crystal p-Amino Acetanilide

    International Nuclear Information System (INIS)

    Saja, D; Joe, I Hubert; Jayakumar, V S

    2006-01-01

    The NIR-FT Raman, FT-IR spectral analysis of potential NLO material P-Amino Acetanilide is carried out by density functional computations. The optimized geometry shows that NH2 and NHCOCH3 groups substituted in para position of phenyl ring are non-planar which predicts maximum conjugation of molecule with donor and acceptor groups. Vibrational analysis reveals that simultaneous IR and Raman activation of the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and the acceptor can make the molecule highly polarized and the intra molecular charge transfer interaction must be responsible for the NLO properties of PAA

  6. Crystal growth, vibrational, optical, thermal and theoretical studies of a nonlinear optical material: 2-Methyl 3,5-dinitrobenzoic acid

    Energy Technology Data Exchange (ETDEWEB)

    Sangeetha, K. [Department of Physics, Sri Sarada College for Women, Salem-16 (India); Guru Prasad, L. [Department of Science & Humanities, M. Kumarasamy College of Engineering, Karur (India); Mathammal, R. [Department of Physics, Sri Sarada College for Women, Salem-16 (India)

    2016-11-15

    Single crystals of 2-methyl 3,5-dinitro benzoic acid with reasonable size have been grown by slow evaporation solution growth method using ethanol as solvent. Quantum chemical calculation of 2-methyl 3,5-Dinitro benzoic acid was carried out by using DFT/B3LYP/6-31+G(d,p) method. The powder X-ray diffraction pattern was recorded and indexed. Both the experimental and theoretical vibrational spectrum validates the presence of functional groups. Polarizability, first order hyperpolarizability and the electric dipole moment values have been computed theoretically. The {sup 1}H and {sup 13}C NMR chemical shift of the molecule was calculated and compared with experimental results. TG/DSC analysis has been employed to understand the thermal and physio-chemical stability of the title compound. Frequency conversion property of the crystal was tested by Kurtz and Perry method. Optical absorption behavior of the grown crystal was examined by recording the optical spectrum and band gap energy was also estimated. The calculated HOMO and LUMO energy shows the charge transfer nature of the molecule.

  7. Nonlinear localized modes in dipolar Bose-Einstein condensates in optical lattices

    International Nuclear Information System (INIS)

    Rojas-Rojas, S.; Vicencio, R. A.; Molina, M. I.; Abdullaev, F. Kh.

    2011-01-01

    Modulational instability and discrete matter wave solitons in dipolar BECs, loaded into a deep optical lattice, are investigated analytically and numerically. The process of modulational instability of nonlinear plane matter waves in a dipolar nonlinear lattice is studied and the regions of instability are established. The existence and stability of bulk discrete solitons are analyzed analytically and confirmed by numerical simulations. In marked contrast with the usual discrete nonlinear Schroedinger behavior (no dipolar interactions), we found a region where the two fundamental modes are simultaneously unstable, allowing enhanced mobility across the lattice for large norm values. To study the existence and properties of surface discrete solitons, an analysis of the dimer configuration is performed. The properties of symmetric and antisymmetric modes including stability diagrams and bifurcations are investigated in closed form. For the case of a bulk medium, properties of fundamental on-site and intersite localized modes are analyzed. On-site and intersite surface localized modes are studied, and we find that they do not exist when nonlocal interactions predominate with respect to local ones.

  8. Noncritical quadrature squeezing in two-transverse-mode optical parametric oscillators

    International Nuclear Information System (INIS)

    Navarrete-Benlloch, Carlos; Roldan, Eugenio; Valcarcel, German J. de; Romanelli, Alejandro

    2010-01-01

    In this article we explore the quantum properties of a degenerate optical parametric oscillator when it is tuned to the first family of transverse modes at the down-converted frequency. Recently we found [C. Navarrete-Benlloch et al., Phys. Rev. Lett. 100, 203601 (2008)] that above threshold a TEM 10 mode following a random rotation in the transverse plane emerges in this system (we denote it as the bright mode), breaking thus its rotational invariance. Then, owing to the mode orientation being undetermined, we showed that the phase quadrature of the transverse mode orthogonal to this one (denoted as the dark mode) is perfectly squeezed at any pump level and without an increase in the fluctuations on its amplitude quadrature (which seems to contradict the uncertainty principle). In this article we go further in the study of this system and analyze some important features not considered previously. First we show that the apparent violation of the uncertainty principle is just that -'apparent' - as the conjugate pair of the squeezed quadrature is not another quadrature but the orientation of the bright mode (which is completely undetermined in the long term). We also study a homodyne scheme in which the local oscillator is not perfectly matched to the dark mode, as this could be impossible in real experiments due to the random rotation of the mode, showing that even in this case large levels of noise reduction can be obtained (also including the experimentally unavoidable phase fluctuations). Finally, we show that neither the adiabatic elimination of the pump variables nor the linearization of the quantum equations are responsible for the remarkable properties of the dark mode (which we prove analytically and through numerical simulations, respectively), which were simplifying assumptions used in Navarrete-Benlloch et al. [Phys. Rev. Lett. 100, 203601 (2008)]. These studies show that the production of noncritically squeezed light through spontaneous rotational

  9. Optical microcavities based on surface modes in two-dimensional photonic crystals and silicon-on-insulator photonic crystals

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Qiu, M.

    2007-01-01

    Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor is gr...... is gradually enhanced and the resonant frequency converges to that of the corresponding surface mode in the photonic crystals. These structures have potential applications such as sensing.......Surface-mode optical microcavities based on two-dimensional photonic crystals and silicon-on-insulator photonic crystals are studied. We demonstrate that a high-quality-factor microcavity can be easily realized in these structures. With an increasing of the cavity length, the quality factor...

  10. Evaluation of coupling terms between intra- and intermolecular vibrations in coarse-grained normal-mode analysis: Does a stronger acid make a stiffer hydrogen bond?

    Science.gov (United States)

    Houjou, Hirohiko

    2011-10-01

    Using theory of harmonic normal-mode vibration analysis, we developed a procedure for evaluating the anisotropic stiffness of intermolecular forces. Our scheme for coarse-graining of molecular motions is modified so as to account for intramolecular vibrations in addition to relative translational/rotational displacement. We applied this new analytical scheme to four carboxylic acid dimers, for which coupling between intra- and intermolecular vibrations is crucial for determining the apparent stiffness of the intermolecular double hydrogen bond. The apparent stiffness constant was analyzed on the basis of a conjunct spring model, which defines contributions from true intermolecular stiffness and molecular internal stiffness. Consequently, the true intermolecular stiffness was in the range of 43-48 N m-1 for all carboxylic acids studied, regardless of the molecules' acidity. We concluded that the difference in the apparent stiffness can be attributed to differences in the internal stiffness of the respective molecules.

  11. A Sub-Hertz, Low-Frequency Vibration Isolation Platform

    Science.gov (United States)

    Ortiz, Gerardo, G.; Farr, William H.; Sannibale, Virginio

    2011-01-01

    One of the major technical problems deep-space optical communication (DSOC) systems need to solve is the isolation of the optical terminal from vibrations produced by the spacecraft navigational control system and by the moving parts of onboard instruments. Even under these vibration perturbations, the DSOC transceivers (telescopes) need to be pointed l000 fs of times more accurately than an RF communication system (parabolic antennas). Mechanical resonators have been extensively used to provide vibration isolation for groundbased, airborne, and spaceborne payloads. The effectiveness of these isolation systems is determined mainly by the ability of designing a mechanical oscillator with the lowest possible resonant frequency. The Low-Frequency Vibration Isolation Platform (LFVIP), developed during this effort, aims to reduce the resonant frequency of the mechanical oscillators into the sub-Hertz region in order to maximize the passive isolation afforded by the 40 dB/decade roll-off response of the resonator. The LFVIP also provides tip/tilt functionality for acquisition and tracking of a beacon signal. An active control system is used for platform positioning and for dampening of the mechanical oscillator. The basic idea in the design of the isolation platform is to use a passive isolation strut with an approximately equal to 100-mHz resonance frequency. This will extend the isolation range to lower frequencies. The harmonic oscillator is a second-order lowpass filter for mechanical disturbances. The resonance quality depends on the dissipation mechanisms, which are mainly hysteretic because of the low resonant frequency and the absence of any viscous medium. The LFVIP system is configured using the well-established Stewart Platform, which consists of a top platform connected to a base with six extensible struts (see figure). The struts are attached to the base and to the platform via universal joints, which permit the extension and contraction of the struts. The

  12. Research on FBG-based longitudinal-acousto-optic modulator with Fourier mode coupling method.

    Science.gov (United States)

    Li, Zhuoxuan; Pei, Li; Liu, Chao; Ning, Tigang; Yu, Shaowei

    2012-10-20

    Fourier mode coupling model was first applied to achieve the spectra property of a fiber Bragg grating (FBG)-based longitudinal-acousto-optic modulator. Compared with traditional analysis algorithms, such as the transfer matrix method, the Fourier mode coupling model could improve the computing efficiency up to 100 times with a guarantee of accuracy. In this paper, based on the theoretical analysis of this model, the spectra characteristics of the modulator in different frequencies and acoustically induced strains were numerically simulated. In the experiment, a uniform FBG was modulated by acoustic wave (AW) at 12 different frequencies. In particular, the modulator responses at 563 and 885.5 KHz with three different lead zirconate titanate (PZT) loads applied were plotted for illustration, and the linear fitting of experimental data demonstrated a good match with the simulation result. The acoustic excitation of the longitudinal wave is obtained using a conic silica horn attached to the surface of a shear-mode PZT plate paralleled to the fiber axis. This way of generating longitudinal AW with a transversal PZT may shed light on the optimal structural design for the FBG-based longitudinal-acousto-optic modulator.

  13. Chains of benzenes with lithium-atom adsorption: Vibrations and spontaneous symmetry breaking

    OpenAIRE

    Ortiz, Yenni P.; Stegmann, Thomas; Klein, Douglas J.; Seligman, Thomas H.

    2016-01-01

    We study effects of different configurations of adsorbates on the vibrational modes as well as symmetries of polyacenes and poly-p-phenylenes focusing on lithium atom adsorption. We found that the spectra of the vibrational modes distinguish the different configurations. For more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essentially followed by the adsorbate. On poly-p-phenylenes we found that lithium adsorption reduces and often eli...

  14. Mode structure in an optically pumped D2O far infrared ring laser

    International Nuclear Information System (INIS)

    Yuan, D.C.; Soumagne, G.; Siegrist, M.R.

    1989-07-01

    The mode structures in an optically pumped D 2 O far infrared ring laser and a corresponding linear resonator have been compared. While single mode operation can be obtained over the whole useful pressure range in the ring structure, this is only possible at pressures greater than 8 Torr in the linear resonator case. A numerical model predicts quite well the pulse shape, pressure dependence and influence of the resonator quality in the ring cavity. (author) 12 figs., 8 refs

  15. Evans hole and non linear optical activity in Bis(melaminium) sulphate dihydrate: A vibrational spectral study.

    Science.gov (United States)

    Suresh Kumar, V R; Binoy, J; Dawn Dharma Roy, S; Marchewka, M K; Jayakumar, V S

    2015-01-01

    Bis(melaminium) sulphate dihydrate (BMSD), an interesting melaminium derivative for nonlinear optical activity, has been subjected to vibrational spectral analysis using FT IR and FT Raman spectra. The analysis has been aided by the Potential Energy Distribution (PED) of vibrational spectral bands, derived using density functional theory (DFT) at B3LYP/6-31G(d) level. The geometry is found to correlate well with the XRD structure and the band profiles for certain vibrations in the finger print region have been theoretically explained using Evans hole. The detailed Natural Bond Orbital (NBO) analysis of the hydrogen bonding in BMSD has also been carried out to understand the correlation between the stabilization energy of hyperconjugation of the lone pair of donor with the σ(∗) orbital of hydrogen-acceptor bond and the strength of hydrogen bond. The theoretical calculation shows that BMSD has NLO efficiency, 2.66 times that of urea. The frontier molecular orbital analysis points to a charge transfer, which contributes to NLO activity, through N-H…O intermolecular hydrogen bonding between the melaminium ring and the sulphate. The molecular electrostatic potential (MEP) mapping has also been performed for the detailed analysis of the mutual interactions between melaminium ring and sulphate ion. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Hand-Arm vibration assessment among tiller operator

    Directory of Open Access Journals (Sweden)

    P. Nassiri

    2013-08-01

    Result: Results of the present study indicated that in all measured situations, exposure to hand arm vibration was higher than the standard limit suggested by Iranian occupational health committee and there was risk of vibration-induced disorders. The maximum exposure to vibration is in plowing ground. Exposure to hand arm vibration in three modes of plowing, transmission and natural, were respectively 16.95, 14.16 and 8.65 meters per second squared. Additionally, in all situations, vibration exposure was highest in the X-axis in comparison with Z- and Y-axes. .Conclusion: This study emphasizes on the need to provide intervention and controlling and managing strategies in order to eliminate or reduce vibration transmitted from tiller to operators hand and arm and also prevent to serious problems including neurovascular disorders, discomfort and white finger syndrome. Meanwhile, more studies are necessary to identify the sources of vibration on different models of tiller.

  17. Free vibration analysis of corroded steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Eslami-Majd, Alireza; Rahbar-Ranji, Ahmad [AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

    2014-06-15

    Vibration analysis of unstiffened/stiffened plates has long been studied due to its importance in the design and condition assessments of ship and offshore structures. Corrosion is inevitable in steel structures and has been so far considered in strength analysis of structures. We studied the free vibration of pitted corroded plates with simply supported boundary conditions. Finite element analysis, with ABAQUS, was used to determine the natural frequencies and mode shapes of corroded plates. Influential parameters including plate aspect ratio, degree of pit, one-sided/both-sided corroded plate, and different corrosion patterns were investigated. By increasing the degree of corrosion, reduction of natural frequency increases. Plate aspect ratio and plate dimensions have no influence on reduction of natural frequency. Different corrosion patterns on the surface of one-sided corroded plates have little influence on reduction of natural frequency. Ratio of pit depth over plate thickness has no influence on the reduction of natural frequency. The reduction of natural frequency in both-sided corroded plates is higher than one-sided corroded plates with the same amount of total corrosion loss. Mode shapes of vibration would change due to corrosion, except square mode shapes.

  18. An analytical study of the free and forced vibration response of a ribbed plate with free boundary conditions

    Science.gov (United States)

    Lin, Tian Ran; Zhang, Kai

    2018-05-01

    An analytical study to predict the vibration response of a ribbed plate with free boundary conditions is presented. The analytical solution was derived using a double cosine integral transform technique and then utilized to study the free and forced vibration of the ribbed plate, as well as the effect of the rib on the modal response of the uniform plate. It is shown that in addition to the three zero-frequency rigid body modes of the plate, the vibration modes of the uniform plate can be classified into four mode groups according to the symmetric properties of the plate with respect to the two orthogonal middle lines parallel to the plate edges. The four mode groups correspond to a double symmetric group, a double anti-symmetric group and two symmetric/anti-symmetric groups. Whilst the inclusion of the rib to the plate is shown to cause distortion to the distribution of vibration modes, most modes can still be traced back to the original modes of the uniform plate. Both the mass and stiffness of the rib are shown to affect the modal vibration of the uniform plate, whereby a dominant effect from the rib mass leads to a decrease in the modal frequency of the plate, whereas a dominant effect from the rib stiffness leads to an increase in plate modal frequency. When the stiffened rib behaves as an effective boundary to the plate vibration, an original plate mode becomes a pair of degenerate modes, whereby one mode has a higher frequency and the other mode has a lower frequency than that of the original mode.

  19. Observation of magnetic domains using a reflection-mode scanning near-field optical microscope

    OpenAIRE

    SHVETS, IGOR

    1997-01-01

    PUBLISHED It is demonstrated that it is possible to image magnetic domains with a resolution of better than 60 nm with the Kerr effect in a reflection-mode scanning near-field optical microscope. Images taken of tracks of thermomagnetically prewritten bits in a Co/Pt multilayer structure magnetized out-of plane showed optical features in a track pattern whose appearance was determined by the position of an analyzer in front of the photomultiplier tube. These features were not apparent in t...

  20. Observation of magnetic domains using a reflection mode scanning near-field optical microscope

    OpenAIRE

    Durkam, C.; Shvets, I.V.; Lodder, J.C.

    1997-01-01

    It is demonstrated that it is possible to image magnetic domains with a resolution of better than 60 nm with the Kerr effect in a reflection-mode scanning near-field optical microscope. Images taken of tracks of thermomagnetically prewritten bits in a Co/Pt multilayer structure magnetized out-of plane showed optical features in a track pattern whose appearance was determined by the position of an analyzer in front of the photomultiplier tube. These features were not apparent in the topography...