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Sample records for sapphire whispering gallery

  1. High-power solid-state sapphire whispering gallery mode maser.

    Science.gov (United States)

    Creedon, Daniel L; Benmessaï, Karim; Tobar, Michael E; Hartnett, John G; Bourgeois, Pierre-Yves; Kersale, Yann; Le Floch, Jean-Michel; Giordano, Vincent

    2010-03-01

    We present new results on a cryogenic solid-state maser frequency standard, which relies on the excitation of whispering gallery (WG) modes within a doped monocrystalline sapphire resonator (alpha-Al2O3). Included substitutively within the highest purity HEMEX-grade sapphire crystal lattice are Fe2+ impurities at a concentration of parts per million, an unavoidable result of the manufacturing process. Mass conversion of Fe2+ to Fe3+ ions was achieved by thermally annealing the sapphire in air. Above-threshold maser oscillation was then excited in the resonator at zero applied DC magnetic field by pumping high-Q WG modes coincident in frequency with the electron spin resonance (ESR) energy levels of the Fe3+ spin population. A 2 stage annealing process was undertaken for a sapphire resonator with exceptionally low Fe3+ concentration, resulting in an improvement of 6 orders of magnitude in output power for this particular crystal, and exceeding the previous best implementation of our scheme in another crystal by nearly 20 dB. This represents an output signal 7 orders of magnitude more powerful than a typical commercial hydrogen maser. At this power level, we estimate a limit on the frequency stability of order 1 x 10(-17)/square root(tau) due to the Schawlow-Townes fundamental thermal noise limit.

  2. High Q-factor Sapphire Whispering Gallery Mode Microwave Resonator at Single Photon Energies and milli-Kelvin Temperatures

    CERN Document Server

    Creedon, Daniel L; Farr, Warrick; Martinis, John M; Duty, Timothy L; Tobar, Michael E

    2011-01-01

    The microwave properties of a crystalline sapphire dielectric whispering gallery mode resonator have been measured at very low excitation strength (E/hf=1) and low temperatures (T = 30 mK). The measurements were sensitive enough to observe saturation due to a highly detuned electron spin resonance, which limited the loss tangent of the material to about 2e-8 measured at 13.868 and 13.259 GHz. Small power dependent frequency shifts were also measured which correspond to an added magnetic susceptibility of order 1e-9. This work shows that quantum limited microwave resonators with Q-factors > 1e8 are possible with the implementation of a sapphire whispering gallery mode system.

  3. Single-crystal sapphire resonator at millikelvin temperatures: Observation of thermal bistability in high- Q factor whispering gallery modes

    Science.gov (United States)

    Creedon, Daniel L.; Tobar, Michael E.; Le Floch, Jean-Michel; Reshitnyk, Yarema; Duty, Timothy

    2010-09-01

    Resonance modes in single crystal sapphire (α-Al2O3) exhibit extremely high electrical and mechanical Q factors ( ≈109 at 4 K), which are important characteristics for electromechanical experiments at the quantum limit. We report the cool down of a bulk sapphire sample below superfluid liquid-helium temperature (1.6 K) to as low as 25 mK. The electromagnetic properties were characterized at microwave frequencies, and we report the observation of electromagnetically induced thermal bistability in whispering gallery modes due to the material T3 dependence on thermal conductivity and the ultralow dielectric loss tangent. We identify “magic temperatures” between 80 and 2100 mK, the lowest ever measured, at which the onset of bistability is suppressed and the frequency-temperature dependence is annulled. These phenomena at low temperatures make sapphire suitable for quantum metrology and ultrastable clock applications, including the possible realization of the quantum-limited sapphire clock.

  4. Neutron whispering gallery

    Science.gov (United States)

    Nesvizhevsky, Valery V.; Voronin, Alexei Yu.; Cubitt, Robert; Protasov, Konstantin V.

    2010-02-01

    The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for atoms and neutrons. For matter waves, it would include a new feature: a massive particle would be settled in quantum states, with parameters depending on its mass. Here, we present for the first time the quantum whispering-gallery effect for cold neutrons. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to the recently discovered gravitationally bound quantum states of neutrons . These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a pure quantum state. Deeply bound whispering-gallery states are long-living and weakly sensitive to surface potential; highly excited states are short-living and very sensitive to the wall potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects.

  5. Proposal for a New Test of the Time Independence Of The Fine Structure Constant, alpha, Using Orthogonally Polarised Whispering Gallery Modes in a Single Sapphire Resonator

    CERN Document Server

    Tobar, M E; Tobar, Michael Edmund; Hartnett, John Gideon

    2003-01-01

    A new experiment to test for the time independence of the fine structure constant, alpha, is proposed. The experiment utilizes orthogonally polarized Transverse Electric and Transverse Magnetic Whispering Gallery Modes in a single sapphire resonator tuned to similar frequencies. When configured as a dual mode sapphire clock, we show that the anisotropy of sapphire makes it is possible to undertake a sensitive measurement from the beat frequency between the two modes. At infrared frequencies this is possible due to the different effect of the lowest phonon frequency on the two orthogonally polarized modes. At microwave frequencies we show that the phonon effect is too small. We show that the Electron Spin Resonance of paramagnetic impurities (such as Cr3+) in the lattice effects only one polarization with an alpha^6 dependence. This enables an enhancement of the sensitivity to temporal changes in a at microwave frequencies.

  6. Whispering Gallery States of Antihydrogen

    CERN Document Server

    Voronin, A Yu; Reynaud, S

    2011-01-01

    We present a theoretical study of the motion of an antihydrogen atom ($\\bar{H}$) near a curved material surface. We predict existence of $\\bar{H}$ atom long-living quasistationary states, localized near the surface due to quantum reflection from the Casimir-Polder/van der Waals potential. Such states are an atom-wave analog of the whispering gallery modes, known in acoustics, optics and neutron physics. We argue that the whispering gallery states of $\\bar{H}$ atoms could be regarded as a full analog of recently predicted gravitational states of $\\bar{H}$, where the centrifugal potential plays a role of the linear gravitational potential.

  7. Hollow Core, Whispering Gallery Resonator Sensors

    CERN Document Server

    Ward, Jonathan M; Chormaic, Síle Nic

    2014-01-01

    A review of hollow core whispering gallery resonators (WGRs)is given. After a short introduction to the topic of whispering gallery resonators we provide a description of whispering gallery modes in hollow or liquid core WGRs. Next, whispering gallery mode (WGM) sensing mechanisms are outlined and some fabrication methods for microbubbles, microcapillaries and other tubular WGM devices are discussed. We then focus on the most common applications of hollow core WGRs, namely refractive index and temperature sensing, gas sensing, force sensing, biosensing, and lasing. The review highlights some of the key papers in this field and gives the reader a general overview of the current state-of-the-art.

  8. Nanofabricated Optomechanical Whispering Gallery Mode Resonators Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Strong interest in whispering gallery mode resonators (WGMR) for use in chip-scale photonic devices is motivated by their high optical quality, mechanical simplicity...

  9. Crystalline Whispering Gallery Mode Resonators: In Search of The Optimal Material

    CERN Document Server

    Ilchenko, V S; Matsko, A B; Maleki, L

    2014-01-01

    Different applications of crystalline whispering gallery mode resonators call for different properties of the resonator host material. We report on our recent study of resonators made out of sapphire, diamond, and quartz crystals and discuss possible applications of these resonators. In particular, we demonstrate Kerr frequency comb generation in sapphire microresonators.

  10. Reconfigurable Optical Spectra from Perturbations on Elliptical Whispering Gallery Resonances

    Science.gov (United States)

    Mohageg, Makan; Maleki, Lute

    2008-01-01

    Elastic strain, electrical bias, and localized geometric deformations were applied to elliptical whispering-gallery-mode resonators fabricated with lithium niobate. The resultant perturbation of the mode spectrum is highly dependant on the modal indices, resulting in a discretely reconfigurable optical spectrum. Breaking of the spatial degeneracy of the whispering-gallery modes due to perturbation is also observed.

  11. Designing whispering gallery modes via transformation optics

    Science.gov (United States)

    Kim, Yushin; Lee, Soo-Young; Ryu, Jung-Wan; Kim, Inbo; Han, Jae-Hyung; Tae, Heung-Sik; Choi, Muhan; Min, Bumki

    2016-10-01

    In dielectric cavities with a rotational symmetry, whispering gallery modes (WGMs) with an extremely long lifetime (that is, a very high Q factor) can be formed by total internal reflection of light around the rim of the cavities. The ultrahigh Q factor of WGMs has enabled a variety of impressive photonic systems, such as ultralow threshold microlasers, bio-sensors with unprecedented sensitivity and cavity optomechanical devices. However, the isotropic emission of WGMs, which is due to the rotational symmetry, is a serious drawback in applications that require directional light sources. Considerable efforts have thus been devoted to achieving directional emission by intentionally breaking the rotational symmetry. However, all of the methods proposed so far have suffered from substantial Q-spoiling. Here, we show how the mode properties of dielectric whispering gallery cavities, such as the Q factor and emission directionality, can be tailored at will using transformation optics. The proposed scheme will open a new horizon of applications beyond the conventional WGMs.

  12. Aptasensors Based on Whispering Gallery Mode Resonators

    Science.gov (United States)

    Nunzi Conti, Gualtiero; Berneschi, Simome; Soria, Silvia

    2016-01-01

    In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR)-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON) ring resonators. PMID:27438861

  13. Aptasensors Based on Whispering Gallery Mode Resonators

    Directory of Open Access Journals (Sweden)

    Gualtiero Nunzi Conti

    2016-07-01

    Full Text Available In this paper, we review the literature on optical evanescent field sensing in resonant cavities where aptamers are used as biochemical receptors. The combined advantages of highly sensitive whispering gallery mode resonator (WGMR-based transducers, and of the unique properties of aptamers make this approach extremely interesting in the medical field, where there is a particularly high need for devices able to provide real time diagnosis for cancer, infectious diseases, or strokes. However, despite the superior performances of aptamers compared to antibodies and WGMR to other evanescent sensors, there is not much literature combining both types of receptors and transducers. Up to now, the WGMR that have been used are silica microspheres and silicon oxynitride (SiON ring resonators.

  14. Optical rogue waves in whispering-gallery-mode resonators

    Science.gov (United States)

    Coillet, Aurélien; Dudley, John; Genty, Goëry; Larger, Laurent; Chembo, Yanne K.

    2014-01-01

    We report a theoretical study showing that rogue waves can emerge in whispering-gallery-mode resonators as the result of the chaotic interplay between Kerr nonlinearity and anomalous group-velocity dispersion. The nonlinear dynamics of the propagation of light in a whispering-gallery-mode resonator is investigated using the Lugiato-Lefever equation, and we give evidence of a range of parameters where rare and extreme events associated with non-Gaussian statistics of the field maxima are observed.

  15. Optical Rogue Waves in Whispering-Gallery-Mode Resonators

    CERN Document Server

    Coillet, Aurélien; Genty, Goery; Larger, Laurent; Chembo, Yanne K

    2014-01-01

    We report a theoretical study showing that rogue waves can emerge in whispering gallery mode resonators as the result of the chaotic interplay between Kerr nonlinearity and anomalous group-velocity dispersion. The nonlinear dynamics of the propagation of light in a whispering gallery-mode resonator is investigated using the Lugiato-Lefever equation, and we evidence a range of parameters where rare and extreme events associated with a non-gaussian statistics of the field maxima are observed.

  16. Reconfigurable Liquid Whispering Gallery Mode Microlasers

    Science.gov (United States)

    Yang, Shancheng; Ta, Van Duong; Wang, Yue; Chen, Rui; He, Tingchao; Demir, Hilmi Volkan; Sun, Handong

    2016-06-01

    Engineering photonic devices from liquid has been emerging as a fascinating research avenue. Reconfigurably tuning liquid optical micro-devices are highly desirable but remain extremely challenging because of the fluidic nature. In this article we demonstrate an all-liquid tunable whispering gallery mode microlaser floating on a liquid surface fabricated by using inkjet print technique. We show that the cavity resonance of such liquid lasers could be reconfigurably manipulated by surface tension alteration originated from the tiny concentration change of the surfactant in the supporting liquid. As such, remarkable sensing of water-soluble organic compounds with a sensitivity of free spectral range as high as 19.85 THz / (mol · mL-1) and the detectivity limit around 5.56 × 10-3 mol · mL-1 is achieved. Our work provides not only a novel approach to effectively tuning a laser resonator but also new insight into potential applications in biological, chemical and environmental sensing.

  17. Characterization of optical whispering gallery mode resonance and applications

    Science.gov (United States)

    Quan, Haiyong

    The whispering-gallery mode microdisk or microsphere resonators have supercompact size, high energy storage, very narrow resonance bandwidth, and high sensitivity. These appealing properties have attracted much attention in the realization of microlasers, narrow filters, optical switching, biosensing, high resolution spectroscopy, and so on. In this dissertation, the optical and energy transport phenomena of whispering-gallery mode resonance and its potentials in some optical sensing applications will be characterized. A 2D theoretical analysis is first presented based on the method of separation of variables and by deriving several appropriate and reasonable boundary conditions to describe the electrical field distribution at resonance modes. This analytical model can precisely predict the intrinsic resonance frequencies of isolated whispering-gallery mode resonators. To consider the coupling of light-delivery waveguides with resonators and investigate the resonance phenomena of the resonator-waveguide system and/or device, simulations using a Finite Element Method solver of Maxwell's equations are conducted. The results indicate the influences of the geometric dimensions, refractive indices, gap distances, and excitation wavelengths on the main characteristics of the resonance modes such as the quality factor Q, the finesse, the mode intensity, and so on. Furthermore, the gap effects are detailedly studied by both theoretical analysis and simulation modeling. The optimal gap for the maximum coupling efficiency and the optimum gap for the best sensing application of the whispering gallery mode resonators are introduced and discussed based on simulation data and theoretical estimations. Three prospective applications of the whispering gallery mode-based sensors are introduced and proof-of-concept studies are demonstrated. The design schemes and fabrication process of the on-chip resonance device made of the Si3N4/SiO2 material system using nanofabrication

  18. QUANTUM LANGEVIN THEORY OF WHISPERING-GALLERY-MODE MICROSPHERE LASER

    Institute of Scientific and Technical Information of China (English)

    CHAI JIN-HUA; LU YI-QUN; LEUNG PUI-TANG

    2000-01-01

    A quantum Langevin theory of whispering-gallery-mode microsphere laser theory is developed. The linear and nonlinear analysis are made for laser operation below and above the threshold. In these analysis, corresponding to the specific property of microsphere, the effect of inversion fluctuation is treated. The coherence functions of laser field are calculated, and the intensity, the amplitude fluctuation and the linewidth of the field are obtained, which are connected with the enhancement factor of whispering-gallery-mode microsphere. It is shown that the strong couple and strong pumping are useful for the amplification of intensity and the decrease of linewidth below the threshold. It is also shown that, for the laser action above threshold, the variances of photon number and the linewidth of internal field are related to the enhancement factor and the square of the enhancement factor, respectively.

  19. Low-Q whispering gallery modes in anisotropic metamaterial shells

    CERN Document Server

    Díaz-Rubio, Ana; Torrent, Daniel; Sánchez-Dehesa, José

    2013-01-01

    Anisotropic and inhomogeneous metamaterial shells are studied in order to exploit all their resonant mode richness. These multilayer structures are based on a cylindrical distribution of radially dependent constitutive parameters including an inner void cavity. Shell, cavity and whispering gallery modes are characterized, and special attention is paid to the latter ones. The whispering gallery modes are created at the boundary layers of the shell with the background and energy localization is produced with highly radiative characteristics. These low-Q resonant states have frequencies that are independent of the shell thickness. However, their quality factors can be controlled by the number of layers forming the shell, which allows confining electromagnetic waves at the interface layers (internal or external), and make them suitable for the harvesting of electromagnetic energy.

  20. MULTIMODE THEORY OF WHISPERING GALLERY-MODE MICROSPHERE LASER

    Institute of Scientific and Technical Information of China (English)

    CHAI JIN-HUA; LU YI-QUN; LEUNG PUI-TANG

    2000-01-01

    A multimode theory of whispering-gallery-mode microsphere laser is developed based on the linear and nonlinear semiclassical theory of the microsphere laser. The average photon-number of each lasing mode and the pumping level requirement for multimode coexistence are derived. The comparison between the theory and experimental results shows that the theory can be used to treat the practical problems on microsphere laser.

  1. Phone-sized whispering-gallery microresonator sensing system

    CERN Document Server

    Xu, Xiangyi; Zhao, Guangming; Yang, Lan

    2016-01-01

    We develop a compact whispering-gallery-mode (WGM) sensing system by integrating multiple components, including a tunable laser, a temperature controller, a function generator, an oscilloscope, a photodiode detector, and a testing computer, into a phone-sized embedded system. We demonstrate a thermal sensing experiment by using this portable system. Such a system successfully eliminates bulky measurement equipment required for characterizing optical resonators and will open up new avenues for practical sensing applications by using ultra-high Q WGM resonators.

  2. Excitation mapping of whispering gallery modes in silica microcavities

    CERN Document Server

    Lin, Guoping; Orucevic, Fedja; Candela, Yves; Jager, Jean-Baptiste; Cai, Zhiping; Lefèvre-Seguin, Valérie; Hare, Jean

    2009-01-01

    We report the direct observation of the electromagnetic-field distribution of whispering?gallery modes in silica microcavities (spheres and toroids). It is revealed by their excitation efficiency with a tapered fiber coupler swept along the meridian. The originality of this method lies in the use of the coupler itself for the near field mapping, eliminating the need of additional tools used in previous work. This method is successfully applied to microspheres and microtoroids

  3. Phone-sized whispering-gallery microresonator sensing system

    Science.gov (United States)

    Xu, Xiangyi; Jiang, Xuefeng; Zhao, Guangming; Yang, Lan

    2016-11-01

    We develop a compact whispering-gallery-mode (WGM) sensing system by integrating multiple components, including a tunable laser, a temperature controller, a function generator, an oscilloscope, a photodiode detector, and a testing computer, into a phone-sized embedded system. We demonstrate a thermal sensing experiment by using this portable system. Such a system successfully eliminates bulky measurement equipment required for characterizing optical resonators and will open up new avenues for practical sensing applications by using ultra-high Q WGM resonators.

  4. Directly mapping whispering gallery modes in a microsphere through modal coupling and directional emission

    Institute of Scientific and Technical Information of China (English)

    Chunhua Dong; Yunfeng Xiao; Yong Yang; Zhengfu Han; Guangcan Guo; Lan Yang

    2008-01-01

    @@ We fabricate slightly deformed fused-silica microspheres in which whispering gallery modes possess remarkably directional escape emission from the microsphere boundary. With efficient flee-space excitation and collection, the lateral spatial distribution of whispering gallery modes with different azimuthal mode numbers, rn, is directly observed through modal coupling and directional emission. Excellent agreement with theory is obtained.

  5. Cylindrical Beam Propagation Modelling of Perturbed Whispering-Gallery Mode Microcavities

    CERN Document Server

    Shirazi, Mohammad Amin Cheraghi; Vincent, Serge; Lu, Tao

    2013-01-01

    We simulate light propagation in perturbed whispering-gallery mode microcavities using a two-dimensional finite-difference beam prop- agation method in a cylindrical coordinate system. Optical properties of whispering-gallery microcavities perturbed by polystyrene nanobeads are investigated through this formulation. The light perturbation as well as quality factor degradation arising from cavity ellipticity are also studied.

  6. Interferometric detection of mode splitting for whispering gallery mode biosensors

    CERN Document Server

    Knittel, Joachim; Lee, Kwan H; Bowen, Warwick P

    2010-01-01

    Sensors based on whispering gallery mode resonators can detect single nanoparticles and even single molecules. Particles attaching to the resonator induce a doublet in the transmission spectrum which provides a self-referenced detection signal. However, in practice this spectral feature is often obscured by the width of the resonance line which hides the doublet structure. This happens particularly in liquid environments that reduce the effective Q factor of the resonator. In this paper we demonstrate an interferometric set-up that allows the direct detection of the hidden doublet and thus provides a pathway for developing practical sensor applications.

  7. Detection limits in plasmonic whispering gallery mode biosensors

    CERN Document Server

    Swaim, Jon D; Bowen, Warwick P

    2011-01-01

    We analyze a whispering gallery mode biosensor with a metallic nanorod bound to its surface. It is found that a localized surface plasmon resonance in the nanorod can reduce the optical mode volume of the resonator by as much as four orders of magnitude via a local enhancement of the electric field, thus improving the detection sensitivity. Optical frequency shifts as large as 15 MHz are predicted for typical proteins and, for typical experimental parameters, the biosensor is predicted to be limited by laser frequency noise, leading to a minimum detectable polarizability on the order of 10 cubic angstroms.

  8. Microtorus a High Finesse Microcavity with Whispering-Gallery Modes

    CERN Document Server

    Ilchenko, V S; Yao, X S; Maleki, L; Ilchenko, Vladimir S.; Gorodetsky, Michael L.; Maleki, Lute

    2000-01-01

    We have demonstrated a 165 micron oblate spheroidal microcavity with free spectral range 383.7 GHz (3.06nm), resonance bandwidth 25 MHz (Q ~ 10^7) at 1550nm, and finesse F > 10^4. The highly oblate spheroidal dielectric microcavity combines very high Q-factor, typical of microspheres, with vastly reduced number of excited whispering-gallery (WG) modes (by two orders of magnitude). The very large free spectral range in the novel microcavity - few hundred instead of few GigaHertz in typical microspheres - is desirable for applications in spectral analysis, narrow-linewidth optical and RF oscillators, and cavity QED.

  9. Method of fabricating a whispering gallery mode resonator

    Science.gov (United States)

    Savchenkov, Anatoliy A. (Inventor); Matkso, Andrey B. (Inventor); Iltchenko, Vladimir S. (Inventor); Maleki, Lute (Inventor)

    2011-01-01

    A method of fabricating a whispering gallery mode resonator (WGMR) is provided. The WGMR can be fabricated from a particular material, annealed, and then polished. The WGMR can be repeatedly annealed and then polished. The repeated polishing of the WGMR can be carried out using an abrasive slurry. The abrasive slurry can have a predetermined, constant grain size. Each subsequent polishing of the WGMR can use an abrasive slurry having a grain size that is smaller than the grain size of the abrasive slurry of the previous polishing iteration.

  10. Optical combs with a crystalline whispering gallery mode resonator

    CERN Document Server

    Savchenkov, Anatoliy A; Ilchenko, Vladimir S; Solomatine, Iouri; Seidel, David; Maleki, Lute

    2008-01-01

    We report on the experimental demonstration of a tunable monolithic optical frequency comb generator. The device is based on the four-wave mixing in a crystalline calcium fluoride whispering gallery mode resonator. The frequency spacing of the comb is given by an integer number of the free spectral range of the resonator. We select the desired number by tuning the pumping laser frequency with respect to the corresponding resonator mode. We also observe interacting optical combs and high-frequency hyperparametric oscillation, depending on the experimental conditions. A potential application of the comb for generating narrowband frequency microwave signals is demonstrated.

  11. Quantum Light from a Whispering-Gallery-Mode Disk Resonator

    DEFF Research Database (Denmark)

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

    2011-01-01

    Optical parametric down-conversion has proven to be a valuable source of nonclassical light. The process is inherently able to produce twin-beam correlations along with individual intensity squeezing of either parametric beam, when pumped far above threshold. Here, we present for the first time...... the direct observation of intensity squeezing of -1.2 dB of each of the individual parametric beams in parametric down-conversion by use of a high quality whispering-gallery-mode disk resonator. In addition, we observed twin-beam quantum correlations of -2.7 dB with this cavity. Such resonators feature...

  12. Optical sum-frequency generation in whispering gallery mode resonators

    CERN Document Server

    Strekalov, Dmitry V; Huang, Yu-Ping; Kumar, Prem

    2013-01-01

    We demonstrate sum-frequency generation in a nonlinear whispering gallery mode resonator between a telecom wavelength and the Rb D2 line, achieved through natural phase matching. Due to the strong optical field confinement and ultra high Q of the cavity, we achieve a 1000-fold enhancement in the conversion efficiency compared to existing waveguide-based devices. The experimental data are in agreement with the nonlinear dynamics and phase matching theory in the spherical geometry employed. The experimental and theoretical results point to a new platform to manipulate the color and quantum states of light waves toward applications such as atomic memory based quantum networking and logic operations with optical signals.

  13. High-Q silk fibroin whispering gallery microresonator

    Science.gov (United States)

    Xu, Linhua; Jiang, Xuefeng; Zhao, Guangming; Ma, Ding; Tao, Hu; Liu, Zhiwen; Omenetto, Fiorenzo G.; Yang, Lan

    2016-09-01

    We have experimentally demonstrated an on-chip all-silk fibroin whispering gallery mode microresonator by using a simple molding and solution-casting technique. The quality factors of the fabricated silk protein microresonators are up to 10^5. A high-sensitivity thermal sensor was realized in this silk fibroin microtoroid with sensitivity of 1.17 nm/K, 8 times higher than previous WGM resonator based thermal sensors. This opens the way to fabricate biodegradable and biocompatible protein based microresonators on a flexible chip for biophotonics applications.

  14. Flow sensor using a hollow whispering gallery mode microlaser

    Science.gov (United States)

    Ward, Jonathan M.; Yang, Yong; Chormaic, Síle N.

    2016-03-01

    Flow sensing using the concept of a hot whispering gallery microlaser is presented. Silica microcapillaries or microbubbles, coated with a layer of erbium:ytterbium (Er:Yb) doped phosphate laser glass, result in a hollow, microbottle-shaped laser geometry. The Er:Yb doped glass outer layer is pumped at 980 nm via a tapered optical fiber and whispering gallery mode (WGM) lasing is recorded at 1535 nm. When gas passes through the capillary, the WGMs shift toward shorter wavelengths due to the cooling effect of the fluid flow. In this way, thermal tuning of the lasing modes over 70 GHz can be achieved. The output end of the capillary is connected to a mass flow sensor and the WGM shift rate as a function of flow rate and pump laser power is measured, with the results fitted using hot wire anemometry theory. Flow sensing can also be realized when the cavity is passively probed at 780 nm, with the estimated Q-factor of the WGMs being in excess of 105.

  15. TeraHz tuning of whispering gallery modes in a PDMS, stand-alone, stretchable microsphere

    CERN Document Server

    Madugani, Ramgopal; Ward, Jonathan M; Riordan, John Daniel; Coppola, Sara; Vespini, Veronica; Grilli, Simonetta; Finizio, Andrea; Ferraro, Pietro; Chormaic, Síle Nic

    2012-01-01

    We report on tuning the optical whispering gallery modes in a poly dimethyl siloxane-based (PDMS) microsphere resonator by more than a THz. The PDMS microsphere system consists of a solid spherical resonator directly formed with double stems on either side. The stems act like tie-rods for simple mechanical stretching of the microresonator over tens of microns, resulting in tuning of the whispering gallery modes by one free spectral range. Further investigations demonstrate that the whispering gallery mode shift has a higher sensitivity (0.13 nm/{\\mu}N) to an applied force when the resonator is in its maximally stretched state compared to its relaxed state.

  16. Predicting the whispering gallery mode spectra of microresonators

    CERN Document Server

    Hall, Jonathan M M; Henderson, Matthew R; Francois, Alexandre; Reynolds, Tess; Riesena, Nicolas; Monro, Tanya M

    2015-01-01

    The whispering gallery modes (WGMs) of optical resonators have prompted intensive research efforts due to their usefulness in the field of biological sensing, and their employment in nonlinear optics. While much information is available in the literature on numerical modeling of WGMs in microspheres, it remains a challenging task to be able to predict the emitted spectra of spherical microresonators. Here, we establish a customizable Finite- Difference Time-Domain (FDTD)-based approach to investigate the WGM spectrum of microspheres. The simulations are carried out in the vicinity of a dipole source rather than a typical plane-wave beam excitation, thus providing an effective analogue of the fluorescent dye or nanoparticle coatings used in experiment. The analysis of a single dipole source at different positions on the surface or inside a microsphere, serves to assess the relative efficiency of nearby radiating TE and TM modes, characterizing the profile of the spectrum. By varying the number, positions and a...

  17. Structural Protein-based Flexible Whispering Gallery Mode Resonators

    CERN Document Server

    Yilmaz, Huzeyfe; Shreiner, Robert; Szwejkowski, Chester J; Jung, Huihun; Hopkins, Patrick; Ozdemir, Sahin Kaya; Yang, Lan; Demirel, Melik C

    2016-01-01

    Nature provides a set of solutions for photonic structures that are finely tuned, organically diverse and optically efficient. Exquisite knowledge of structure-property relationships in proteins aids in the design of materials with desired properties for building devices with novel functionalities, which are difficult to achieve or previously unattainable. Recent bio-inspired photonic platforms made from proteinaceous materials lay the groundwork for many functional device applications, such as electroluminescence in peptide nucleic acids1, multiphoton absorption in amyloid fibers2 and silk waveguides and inverse opals3-5. Here we report whispering-gallery-mode (WGM) microresonators fabricated entirely from semi-crystalline structural proteins (i.e., squid ring teeth, SRT, from Loligo vulgaris and its recombinant, and silk from Bombyx mori) with unconventional thermo-optic response. We present a striking example of how small modifications at the molecular level lead to structural changes and alter macroscopic...

  18. Nonlinear and quantum optics with whispering gallery resonators

    Science.gov (United States)

    Strekalov, Dmitry V.; Marquardt, Christoph; Matsko, Andrey B.; Schwefel, Harald G. L.; Leuchs, Gerd

    2016-12-01

    Optical whispering gallery modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon has a rather general nature, equally applicable to sound and all other waves. It enables resonators of unique properties attractive both in science and engineering. Very high quality factors of optical WGM resonators persisting in a wide wavelength range spanning from radio frequencies to ultraviolet light, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

  19. Detecting single viruses and nanoparticles using whispering gallery microlasers

    CERN Document Server

    He, Lina; Zhu, Jiangang; Kim, Woosung; Yang, Lan

    2011-01-01

    Detection and characterization of individual nano-scale particles, virions, and pathogens are of paramount importance to human health, homeland security, diagnostic and environmental monitoring[1]. There is a strong demand for high-resolution, portable, and cost-effective systems to make label-free detection and measurement of individual nanoparticles, molecules, and viruses [2-6]. Here, we report an easily accessible, real-time and label-free detection method with single nanoparticle resolution that surpasses detection limit of existing micro- and nano-photonic devices. This is achieved by using an ultra-narrow linewidth whispering gallery microlaser, whose lasing line undergoes frequency splitting upon the binding of individual nano-objects. We demonstrate detection of polystyrene and gold nanoparticles as small as 15 nm and 10 nm in radius, respectively, and Influenza A virions by monitoring changes in self-heterodyning beat note of the split lasing modes. Experiments are performed in both air and aqueous ...

  20. Nonlinear and Quantum Optics with Whispering Gallery Resonators

    CERN Document Server

    Strekalov, Dmitry V; Matsko, Andrey B; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical Whispering Gallery Modes (WGMs) derive their name from a famous acoustic phenomenon of guiding a wave by a curved boundary observed nearly a century ago. This phenomenon was later realized to have a rather general nature, equally applicable to sound and all other waves, but in particular also to electromagnetic waves ranging from radio frequencies to ultraviolet light. Very high quality factors of optical WGM resonators persisting in a wide wavelength range, their small mode volume, and tunable in- and out- coupling make them exceptionally efficient for nonlinear optical applications. Nonlinear optics facilitates interaction of photons with each other and with other physical systems, and is of prime importance in quantum optics. In this paper we review numerous applications of WGM resonators in nonlinear and quantum optics. We outline the current areas of interest, summarize progress, highlight difficulties, and discuss possible future development trends in these areas.

  1. Elementary modes of coupled oscillators as whispering-gallery microresonators

    Science.gov (United States)

    Banerjee, Rabin; Mukherjee, Pradip

    2015-10-01

    We obtain the elementary modes of a system of parity-time reversal (PT)-symmetric coupled oscillators with balanced loss and gain. These modes are used to give a physical picture of the phase transition recently reported [C. M. Bender, M. Gianfreda, B. Peng, S. K. Özdemir and L. Yang, Phys. Rev. A 88, 062111 (2013); L. Yang, S. K. Özdemir and B. Peng, 12th Int. Workshop and Conf. Pseudo-Hermitian Hamiltonians in Quantum Physics, Istanbul, Turkey, July 2013; B. Peng, S. K. Özdemir, F. Lei, F. Monifi, M. Gianfreda, G. L. Long, S. Fan, F. Nori, C. M. Bender and L. Yang, Nat. Phys. 10, 394 (2014)] in experiments with whispering-gallery microresonators.

  2. Highly Efficient Boundary Element Analysis of Whispering Gallery Microcavities

    CERN Document Server

    Pan, Leyuan

    2014-01-01

    We demonstrate that the efficiency of the boundary element whispering gallery microcavity analysis can be improved by orders of magnitude with the inclusion of Fresnel approximation. Using this formulation, simulation of a microdisk with wave-number-radius product as large as $kR\\approx8,000$ was demonstrated in contrast to a previous record of $kR\\approx100$. In addition to its high accuracy on computing the modal field distribution and resonance wavelength, this method yields a relative error of $10%$ in calculating the quality factor as high as $10^{11}$ through a direct root searching method where the conventional boundary element method failed to achieve. Finally, quadrupole shaped cavities and double disks as large as $100 {\\mu}m$ in diameter were modeled by employing as few as $512$ boundary elements whilst the simulation of such large cavities using conventional boundary element method were not reported previously.

  3. Broadband second harmonic generation in whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Strekalov, Dmitry V; Yu, Nan

    2013-01-01

    Optical frequency conversion processes in nonlinear materials are limited in wavelength by the accessible phase matching and the required high pump powers. In this letter, we report a novel broadband phase matching (PM) technique in high quality factor (Q) whispering gallery mode (WGM) resonators made of birefringent crystalline materials. This technique relies on two interacting WGMs, one with constant and the other with spatially oscillating phase velocity. Thus, phase matching occurs cyclically. The technique can be implemented with a WGM resonator with its disk plane parallel to the optic axis of the crystal. With a single beta barium borate (BBO) resonator in that configuration, we experimentally demonstrated efficient second harmonic generation (SHG) to harmonic wavelengths from 780 nm in the near infrared to 317 nm in the ultraviolet (UV). The observed SHG conversion efficiency is as high as 4.6% (mW)-1. This broadband PM technique opens a new way for nonlinear optics applications in WGM resonators. Th...

  4. Polarization-selective out-coupling of whispering gallery modes

    CERN Document Server

    Sedlmeir, Florian; Vogl, Ulrich; Zeltner, Richard; Schunk, Gerhard; Strekalov, Dmitry V; Marquardt, Christoph; Leuchs, Gerd; Schwefel, Harald G L

    2016-01-01

    Whispering gallery mode (WGM) resonators are an important building block for linear, nonlinear and quantum optical experiments. In such experiments, independent control of coupling rates to different modes can lead to improved conversion efficiencies and greater flexibility in generation of non-classical states based on parametric down conversion. In this work, we introduce a scheme which enables selective out-coupling of WGMs belonging to a specific polarization family, while the orthogonally polarized modes remain largely unperturbed. Our technique utilizes material birefringence in both the resonator and coupler such that a negative (positive) birefringence allows selective coupling to TE (TM) polarized WGMs. We formulate a new coupling condition suitable for describing the case where the refractive indices of the resonator and the coupler are almost the same, from which we derive the criterion for polarization-selective coupling. We experimentally demonstrate our proposed method using a lithium niobate di...

  5. Microwave Photonics Systems Based on Whispering-gallery-mode Resonators

    Science.gov (United States)

    Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K.

    2013-01-01

    Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency. PMID:23963358

  6. Rarefying Spectra of Whispering-Gallery-Mode Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy; Matsko, Andrey; Strekalov, Dmitri; Iltchenko, Vladimir; Maleki, Lute

    2007-01-01

    A method of cleaning the mode spectra of whispering-gallery-mode (WGM) optical resonators has been devised to make such resonators more suitable for use as narrow-band optical filters. The method applies, more specifically, to millimeter- sized whispering-gallery-mode optical resonators that are made of crystalline electro-optical materials and have ultrahigh values of the resonance quality factor (Q). The mode spectrum of such a resonator is typically dense, consisting of closely spaced families of modes; as such, the spectrum is not well suited for narrow-band filtering, in which there is a need for strong rejection of side modes. Cleaning as used here signifies rarefying the spectrum so that what remains consists mostly of a single desired family of modes or, at worst, a few mode families that are more widely spaced in frequency than are the mode families in the original, non-rarefied spectrum. The spectrum-cleaning method exploits the fact that various WGM mode families occupy various positions near the equator at the rim of a resonator disk. In this method, a damper in the form of a prism or other polished piece of material having an index of refraction greater than that of the resonator material is placed in contact with the rim of the resonator at such a position that the Qs of most or all of the undesired mode families are greatly reduced while the Q of the desired mode family is reduced by only a tolerably small amount. In an alternative method that has been considered, the mode spectrum would be cleaned through special design of the shape of the rim, but fabrication of the rim in a special shape is a complicated task. The advantage of the present method, relative to the alternative method, is that special shaping of the rim is not necessary and the damping prism can be emplaced after the resonator has been fabricated.

  7. Microwave photonics systems based on whispering-gallery-mode resonators.

    Science.gov (United States)

    Coillet, Aurélien; Henriet, Rémi; Phan Huy, Kien; Jacquot, Maxime; Furfaro, Luca; Balakireva, Irina; Larger, Laurent; Chembo, Yanne K

    2013-08-05

    Microwave photonics systems rely fundamentally on the interaction between microwave and optical signals. These systems are extremely promising for various areas of technology and applied science, such as aerospace and communication engineering, sensing, metrology, nonlinear photonics, and quantum optics. In this article, we present the principal techniques used in our lab to build microwave photonics systems based on ultra-high Q whispering gallery mode resonators. First detailed in this article is the protocol for resonator polishing, which is based on a grind-and-polish technique close to the ones used to polish optical components such as lenses or telescope mirrors. Then, a white light interferometric profilometer measures surface roughness, which is a key parameter to characterize the quality of the polishing. In order to launch light in the resonator, a tapered silica fiber with diameter in the micrometer range is used. To reach such small diameters, we adopt the "flame-brushing" technique, using simultaneously computer-controlled motors to pull the fiber apart, and a blowtorch to heat the fiber area to be tapered. The resonator and the tapered fiber are later approached to one another to visualize the resonance signal of the whispering gallery modes using a wavelength-scanning laser. By increasing the optical power in the resonator, nonlinear phenomena are triggered until the formation of a Kerr optical frequency comb is observed with a spectrum made of equidistant spectral lines. These Kerr comb spectra have exceptional characteristics that are suitable for several applications in science and technology. We consider the application related to ultra-stable microwave frequency synthesis and demonstrate the generation of a Kerr comb with GHz intermodal frequency.

  8. Whispering galleries and the control of artificial atoms.

    Science.gov (United States)

    Forrester, Derek Michael; Kusmartsev, Feodor V

    2016-04-28

    Quantum computation using artificial-atoms, such as novel superconducting circuits, can be sensitively controlled by external electromagnetic fields. These fields and the self-fields attributable to the coupled artificial-atoms influence the amount of quantum correlation in the system. However, control elements that can operate without complete destruction of the entanglement of the quantum-bits are difficult to engineer. Here we investigate the possibility of using closely-spaced-linear arrays of metallic-elliptical discs as whispering gallery waveguides to control artificial-atoms. The discs confine and guide radiation through the array with small notches etched into their sides that act as scatterers. We focus on π-ring artificial-atoms, which can generate their own spontaneous fluxes. We find that the micro-discs of the waveguides can be excited by terahertz frequency fields to exhibit whispering-modes and that a quantum-phase-gate composed of π-rings can be operated under their influence. Furthermore, we gauge the level of entanglement through the concurrence measure and show that under certain magnetic conditions a series of entanglement sudden-deaths and revivals occur between the two qubits. This is important for understanding the stability and life-time of qubit operations using, for example, a phase gate in a hybrid of quantum technologies composed of control elements and artificial-atoms.

  9. Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

    2006-01-01

    Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

  10. Optofluidic whispering gallery mode microcapillary lasers for refractive index sensing

    Science.gov (United States)

    François, Alexandre; Riesen, Nicolas; Gardner, Kristy; Monro, Tanya M.; Meldrum, Al

    2016-12-01

    Whispering gallery modes (WGMs) allow for remarkable refractive index sensing performance with extremely low detection limits, and thus have found use in various emerging label free biosensing applications. Among the different types of resonators which have been studied, microcapillaries have the unique property of having the evanescent fields extend into and sample the medium inside the resonator, which is particularly interesting because the resonator itself serves as a microfluidic channel. Here, lasing of the WGMs in fluorescent microcapillaries is demonstrated for the first time, and their application to refractive index sensing is investigated. The laser gain medium used here is embedded inside a high refractive index polymer coating deposited onto the inner surface of the capillary. Lasing can only be realized for thick polymer coatings (in this case >= 800 nm), with higher Q factor but also stronger confinement of the propagating wave, which lowers the refractive index sensitivity compared to non-lasing capillaries which can have thinner polymer coatings. We however find that the large improvement in signal-to-noise ratio and Q factor realized upon lasing more than compensates for the reduced sensitivity, resulting in an order-of-magnitude improvement in the detection limit for refractive index sensing.

  11. Protein-based flexible whispering gallery mode resonators

    Science.gov (United States)

    Yilmaz, Huzeyfe; Pena-Francesch, Abdon; Xu, Linhua; Shreiner, Robert; Jung, Huihun; Huang, Steven H.; Özdemir, Sahin K.; Demirel, Melik C.; Yang, Lan

    2016-02-01

    The idea of creating photonics tools for sensing, imaging and material characterization has long been pursued and many achievements have been made. Approaching the level of solutions provided by nature however is hindered by routine choice of materials. To this end recent years have witnessed a great effort to engineer mechanically flexible photonic devices using polymer substrates. On the other hand, biodegradability and biocompatibility still remains to be incorporated. Hence biomimetics holds the key to overcome the limitations of traditional materials in photonics design. Natural proteins such as sucker ring teeth (SRT) and silk for instance have remarkable mechanical and optical properties that exceed the endeavors of most synthetic and natural polymers. Here we demonstrate for the first time, toroidal whispering gallery mode resonators (WGMR) fabricated entirely from protein structures such as SRT of Loligo vulgaris (European squid) and silk from Bombyx mori. We provide here complete optical and material characterization of proteinaceous WGMRs, revealing high quality factors in microscale and enhancement of Raman signatures by a microcavity. We also present a most simple application of a WGMR as a natural protein add-drop filter, made of SRT protein. Our work shows that with protein-based materials, optical, mechanical and thermal properties can be devised at the molecular level and it lays the groundwork for future eco-friendly, flexible photonics device design.

  12. High-Q whispering-gallery mode sensor in liquids

    Science.gov (United States)

    Nadeau, Jay L.; Ilchenko, Vladimir S.; Kossakovski, Dmitri; Bearman, Gregory H.; Maleki, Lute

    2002-06-01

    Optical sensing of biomolecules on microfabricated glass surfaces requires surface coatings that minimize nonspecific binding while preserving the optical properties of the sensor. Microspheres with whispering-gallery (WG) modes can achieve quality factor (Q) levels many orders of magnitude greater than those of other WG-based microsensors: greater than 1010 in air, and greater than 109 in a variety of solvents, including methanol, H2O and phosphate buffered saline (PBS). The presence of dyes that absorb in the wavelength of the WG excitation in the evanescent zone can cause this Q value to drop by almost 3 orders of magnitude. Silanization of the surface with mercapto-terminal silanes is compatible with high Q (>109), but chemical cross-linking of streptavidin reduces the Q to 105-106 due to build-up of a thick, irregular layer of protein. However, linkage of biotin to the silane terminus preserves the Q at a ~2x107 and yields a reactive surface sensitive to avidin-containing ligands in a concentration-dependent manner. Improvements in the reliability of the surface chemistry show promise for construction of an ultrasensitive biosensor.

  13. 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.

  14. Whispering Gallery Modes in Hexagonal Zinc Oxide Micro- and Nanocrystals

    Science.gov (United States)

    Nobis, Thomas; Kaidashev, Evgeni M.; Rahm, Andreas; Lorenz, Michael; Grundmann, Marius

    The resonator properties of zinc oxide (ZnO) micro- and nanocrystals grown by a novel high pressure pulsed laser deposition process have been investigated at room temperature by cathodoluminescence (CL), spatially resolved CL-imaging and polarization resolved micro-photoluminescence (μ-PL) within the visible spectral range. The spectra exhibit a series of comparatively sharp and almost equidistant resonance lines. Using a simple plane wave interference model and taking into account the spectral characteristic n(ω) of the refractive index of ZnO, we can unambiguously attribute those lines to whispering gallery modes (WGMs) of a two dimensional hexagonal resonator. The predicted resonator diameters agree well with the measured crystal sizes. Tapered, high aspect ratio ZnO nanoneedles furthermore allow systematic investigations of the WGMs as a function of cavity diameter D down to zero. Hence, the transition from a multi-mode to a single mode cavity is directly observed. μ-PL experiments demonstrate that the WGMs are mainly TM polarized.

  15. Whispering Gallery Mode Microresonators for Lasing and Single Nanoparticle Detection

    Science.gov (United States)

    He, Lina

    Whispering gallery mode (WGM) microresonators have attracted great interests due to the significantly enhanced light-matter interactions originating from their high quality factors and small mode volumes. They are suitable for a wide range of applications including sensing, lasing, nonlinear optics, and so forth. However, temperature fluctuations as one of the most common environmental noises disturb the cavity resonances and thus degrade the device stability and sensitivity. We introduce a wetting technique to coat the silica resonator with a thin layer of polymer which has the negative thermo-optic coefficient to compensate for the thermal effect in silica, and demonstrate complete thermal compensation. WGM microresonators have shown great promise for ultra-sensitive and label-free chemical and biological sensing by probing the surroundings with evanescent waves leaking out of the resonator. Sensing is achieved by monitoring the shift or splitting of a resonant frequency. The detection limit is determined by the linewidth of the resonant mode which is ultimately limited by material absorption induced loss. To surpass the limit of passive resonators, we report real-time single nanoparticle detection using on-chip WGM microcavity lasers. The ultra-low threshold microlasers are prepared by doping WGM resonators with rare-earth ions through the sol-gel method, and their linewidths are much narrower than the passive counterparts. The detection approach relies on measuring changes in the heterodyne beat note of two split modes originating from splitting of a narrow emission line in the microlaser induced by nanoscale objects. We demonstrate detection of polystyrene and gold nanoparticles as small as 15 nm and 10 nm in radius, respectively, and Influenza A virions by monitoring changes in the beat note of the split lasing modes. The self-heterodyne interferometric method achieved in the on-chip microlaser provides a self-referencing scheme with extraordinary sensitivity

  16. Identifying modes of large whispering-gallery mode resonators from the spectrum and emission pattern

    DEFF Research Database (Denmark)

    Schunk, Gerhard; Fuerst, Josef U.; Förtsch, Michael;

    2014-01-01

    Identifying the mode numbers in whispering-gallery mode resonators (WGMRs) is important for tailoring them to experimental needs. Here we report on a novel experimental mode analysis technique based on the combination of frequency analysis and far-field imaging for high mode numbers of large WGMRs....... The radial mode numbers q and the angular mode numbers p = l-m are identified and labeled via far-field imaging. The polar mode numbers l are determined unambiguously by fitting the frequency differences between individual whispering gallery modes (WGMs). This allows for the accurate determination...

  17. Using Whispering-Gallery-Mode Resonators for Refractometry

    Science.gov (United States)

    Matsko, Andrey; Savchenkov, Anatoliy; Strekalov, Dmitry; Iltchenko, Vladimir; Maleki, Lute

    2010-01-01

    A method of determining the refractive and absorptive properties of optically transparent materials involves a combination of theoretical and experimental analysis of electromagnetic responses of whispering-gallery-mode (WGM) resonator disks made of those materials. The method was conceived especially for use in studying transparent photorefractive materials, for which purpose this method affords unprecedented levels of sensitivity and accuracy. The method is expected to be particularly useful for measuring temporally varying refractive and absorptive properties of photorefractive materials at infrared wavelengths. Still more particularly, the method is expected to be useful for measuring drifts in these properties that are so slow that, heretofore, the properties were assumed to be constant. The basic idea of the method is to attempt to infer values of the photorefractive properties of a material by seeking to match (1) theoretical predictions of the spectral responses (or selected features thereof) of a WGM of known dimensions made of the material with (2) the actual spectral responses (or selected features thereof). Spectral features that are useful for this purpose include resonance frequencies, free spectral ranges (differences between resonance frequencies of adjacently numbered modes), and resonance quality factors (Q values). The method has been demonstrated in several experiments, one of which was performed on a WGM resonator made from a disk of LiNbO3 doped with 5 percent of MgO. The free spectral range of the resonator was approximately equal to 3.42 GHz at wavelengths in the vicinity of 780 nm, the smallest full width at half maximum of a mode was approximately equal to 50 MHz, and the thickness of the resonator in the area of mode localization was 30 microns. In the experiment, laser power of 9 mW was coupled into the resonator with an efficiency of 75 percent, and the laser was scanned over a frequency band 9 GHz wide at a nominal wavelength of

  18. Demonstration of whispering-gallery-mode resonant enhancement of optical forces

    CERN Document Server

    Li, Yangcheng; Limberopoulos, Nicholaos I; Astratov, Vasily N

    2015-01-01

    We experimentally studied whispering-gallery modes(WGMs) and demonstrated resonance enhancement of optical forces evanescently exerted on dielectric microspheres. We showed that the resonant light pressure can be used for optical sorting of microparticles with extraordinary uniform resonant properties that is unachievable by conventional sorting techniques.

  19. Brillouin Lasing with a CaF_2 Whispering Gallery Mode Resonator

    CERN Document Server

    Grudinin, Ivan S; Maleki, Lute

    2008-01-01

    Stimulated Brillouin scattering with both pump and Stokes beams in resonance with whispering gallery modes of an ultra high Q CaF_2 resonator is demonstrated for the first time. The resonator is pumped with 1064 nm light and has a Brillouin lasing threshold of 3.5 microwatt. Potential applications include optical generation of microwaves and sensitive gyros.

  20. All-optical switching and strong coupling using tunable whispering-gallery-mode microresonators

    NARCIS (Netherlands)

    O'Shea, D.; Junge, C.; Poellinger, M.; Vogler, A.; Rauschenbeutel, A.

    2011-01-01

    We review our recent work on tunable, ultra-high quality factor whispering-gallery-mode bottle microresonators and highlight their applications in non-linear optics and in quantum optics experiments. Our resonators combine ultra-high quality factors of up to Q=3.6x10(8), a small mode volume, and nea

  1. Highly Stable On-Chip Embedded Organic Whispering Gallery Mode Lasers

    NARCIS (Netherlands)

    Lu, Shi-Yang; Fang, Hong-Hua; Feng, Jing; Xia, Hong; Zhang, Tie-Qiang; Chen, Qi-Dai; Sun, Hong-Bo; Fang, Honghua

    2014-01-01

    Chip-embedded organic resonator is fabricated with 2,5-Bis(4-biphenylyl)thiophene (BP1T) crystals encapsulated with polydimethylsiloxane (PDMS). Whispering gallery mode lasing is demonstrated in these on-chip embedded crystalline microresonators, without decline in the spectral properties, and perfo

  2. All-optical Photonic Oscillator with High-Q Whispering Gallery Mode Resonators

    Science.gov (United States)

    Savchenkov, Anatoliy A.; Matsko, Andrey B.; Strekalov, Dmitry; Mohageg, Makan; Iltchenko, Vladimir S.; Maleki, Lute

    2004-01-01

    We demonstrated low threshold optical photonic hyper-parametric oscillator in a high-Q 10(exp 10) CaF2 whispering gallery mode resonator which generates stable 8.5 GHz signal. The oscillations result from the resonantly enhanced four wave mixing occurring due to Kerr nonlinearity of the material.

  3. Whispering gallery mode resonators for frequency metrology applications

    Science.gov (United States)

    Baumgartel, Lukas

    This dissertation describes an investigation into the use of whispering gallery mode (WGM) resonators for applications towards frequency reference and metrology. Laser stabilization and the measurement of optical frequencies have enabled myriad technologies of both academic and commercial interest. A technology which seems to span both motivations is optical atomic clocks. These devices are virtually unimaginable without the ultra stable lasers plus frequency measurement and down-conversion afforded by Fabry Perot (FP) cavities and model-locked laser combs, respectively. However, WGM resonators can potentially perform both of these tasks while having the distinct advantages of compactness and simplicity. This work represents progress towards understanding and mitigating the performance limitations of WGM cavities for such applications. A system for laser frequency stabilization to a the cavity via the Pound-Drever-Hall (PDH) method is described. While the laser lock itself is found to perform at the level of several parts in 1015, a variety of fundamental and technical mechanisms destabilize the WGM frequency itself. Owing to the relatively large thermal expansion coefficients in optical crystals, environmental temperature drifts set the stability limit at time scales greater than the thermal relaxation time of the crystal. Uncompensated, these drifts pull WGM frequencies about 3 orders of magnitude more than they would in an FP cavity. Thus, two temperature compensation schemes are developed. An active scheme measures and stabilizes the mode volume temperature to the level of several nK, reducing the effective temperature coefficient of the resonator to 1.7x10-7 K-1; simulations suggest that the value could eventually be as low as 3.5x10-8 K-1, on par with the aforementioned FP cavities. A second, passive scheme is also described, which employs a heterogeneous resonator structure that capitalizes on the thermo-mechanical properties of one material and the optical

  4. Detection and identification of microparticles/nanoparticles and blood components using optical resonance of whispering-gallery modes in microspheres

    Science.gov (United States)

    Tcherniavskaia, E. A.; Saetchnikov, V. A.

    2010-11-01

    We present experimental data on the dependence of optical resonance spectra of whispering-gallery modes in dielectric microspheres on the constituent composition of solutions modeling blood plasma and also containing disease indicators and virus ghosts. We observe substantial changes in the optical resonance spectra of whispering-gallery modes, associated both with a change in the macroscopic parameters of the microsphere environment and with possible interaction between the microsphere surface and components of the solution.

  5. Surface optomechanics: Calculating optically excited acoustical whispering gallery modes in microspheres

    CERN Document Server

    Zehnpfennig, John; Tomes, Matthew; Carmon, Tal

    2011-01-01

    Stimulated Brillouin scattering recently allowed experimental excitation of surface acoustic resonances in micro-devices, enabling vibration at rates in the range of 50 MHz to 12 GHz. The experimental availability of such mechanical whispering gallery modes in photonic-MEMS raises questions on their structure and spectral distribution. Here we calculate the form and frequency of such vibrational surface whispering gallery modes, revealing diverse types of surface vibrations including longitudinal, transverse, and Rayleigh-type deformations. We parametrically investigate these various modes by changing their orders in the azimuthal, radial, and polar directions to reveal different vibrational structures including mechanical resonances that are localized near the interface with the environment where they can sense changes in the surroundings.

  6. White-Light Whispering Gallery Mode Optical Resonator System and Method

    Science.gov (United States)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy A. (Inventor); Maleki, Lute (Inventor)

    2009-01-01

    An optical resonator system and method that includes a whispering-gallery mode (WGM) optical resonator that is capable of resonating across a broad, continuous swath of frequencies is provided. The optical resonator of the system is shaped to support at least one whispering gallery mode and includes a top surface, a bottom surface, a side wall, and a first curved transition region extending between the side wall and the top surface. The system further includes a coupler having a coupling surface which is arranged to face the transition region of the optical resonator and in the vicinity thereof such that an evanescent field emitted from the coupler is capable of being coupled into the optical resonator through the first curved transition region

  7. Physics. Creating and probing electron whispering-gallery modes in graphene.

    Science.gov (United States)

    Zhao, Yue; Wyrick, Jonathan; Natterer, Fabian D; Rodriguez-Nieva, Joaquin F; Lewandowski, Cyprian; Watanabe, Kenji; Taniguchi, Takashi; Levitov, Leonid S; Zhitenev, Nikolai B; Stroscio, Joseph A

    2015-05-01

    The design of high-finesse resonant cavities for electronic waves faces challenges due to short electron coherence lengths in solids. Complementing previous approaches to confine electronic waves by carefully positioned adatoms at clean metallic surfaces, we demonstrate an approach inspired by the peculiar acoustic phenomena in whispering galleries. Taking advantage of graphene's gate-tunable light-like carriers, we create whispering-gallery mode (WGM) resonators defined by circular pn junctions, induced by a scanning tunneling probe. We can tune the resonator size and the carrier concentration under the probe in a back-gated graphene device over a wide range. The WGM-type confinement and associated resonances are a new addition to the quantum electron-optics toolbox, paving the way to develop electronic lenses and resonators.

  8. High-Q MgF₂ whispering gallery mode resonators for refractometric sensing in aqueous environment.

    Science.gov (United States)

    Sedlmeir, Florian; Zeltner, Richard; Leuchs, Gerd; Schwefel, Harald G L

    2014-12-15

    We present our experiments on refractometric sensing with ultrahigh-Q, crystalline, birefringent magnesium fluoride (MgF₂) whispering gallery mode resonators. The difference to fused silica which is most commonly used for sensing experiments is the small refractive index of MgF₂ which is very close to that of water. Compared to fused silica this leads to more than 50% longer evanescent fields and a 4.25 times larger sensitivity. Moreover the birefringence amplifies the sensitivity difference between TM and TE type modes which will enhance sensing experiments based on difference frequency measurements. We estimate the performance of our resonators and compare them with fused silica theoretically and present experimental data showing the interferometrically measured evanescent field decay and the sensitivity of mm-sized MgF₂ whispering gallery mode resonators immersed in water. These data show reasonable agreement with the developed theory. Furthermore, we observe stable Q factors in water well above 1 × 10⁸.

  9. Whispering-gallery microcavity semiconductor lasers suitable for photonic integrated circuits and optical interconnects

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The characteristics of whispering-gallery-like modes in the equilateral triangle and square microresonators are introduced,including directional emission triangle and square microlasers connected to an output waveguide.We propose a photonic interconnect scheme by connecting two directional emission microlasers with an optical waveguide on silicon integrated circuit chip.The measurement indicates that the triangle microlasers can work as a resonance enhanced photodetector for optical interconnect.

  10. Spectral Singularities and Whispering Gallery Modes of a Cylindrical Gain Medium

    OpenAIRE

    Mostafazadeh, Ali; Sarısaman, Mustafa

    2013-01-01

    PHYSICAL REVIEW A 87, 063834 (2013) Spectral singularities and whispering gallery modes of a cylindrical gain medium Ali Mostafazadeh* and Mustafa Sarısaman Department of Mathematics, Koc¸ University, Sarıyer 34450, Istanbul, Turkey (Received 11 February 2013; published 20 June 2013) Complex scattering potentials can admit scattering states that behave exactly like a zero-width resonance. Their energy is what mathematicians call a spectral singularity. This phenomenon admits...

  11. High-Q whispering gallery modes in a polymer microresonator with broad strain tuningHigh-Q whispering gallery modes in a polymer microresonator with broad strain tuning

    Institute of Scientific and Technical Information of China (English)

    ZHOU ZhongHao[1,3; SHU FangJie[1,2; SHEN Zhen[1,3; DONG ChunHua[1,3; GUO GuangCan[1,3

    2015-01-01

    We have reported the high-Q whispering gallery modes (WGMs) in a polydimethylsiloxane (PDMS) optical microresonators with broad tuning range. The PDMS microresonators are fabricated at the center of two collimating fiber tips, which can be controlled by the piezoelectric stage. Through stretching the fiber stem, the tuning range of WGMs are demonstrated more than 50 nm. Further investigations demonstrated that the WGM shift has a high force sensitivity (- 19.7 pm/p.N) of the gravitation when the microcavity is stretched by a weight. The theoretical analysis reveals that the high force sensitivity of polymer microresonator can be used for the weak force or height measurement.

  12. Macrobending Loss Measurements of G.657 Fiber with Suppression of Ripple Effect Induced by Whispering Gallery Modes

    Science.gov (United States)

    Li, Chunsheng; Wang, Tao; Li, Linyin; Zhang, Xiaoguang

    2016-02-01

    During the macrobending loss performance tests of ITU-T G.657 fiber under small bending radius, the test results show big differencesin many tests for the same test samples and conditions. Research shows that the main reason for the difference is Whispering gallery modes phenomenon in small bending radius [1]. The inappropriate test conditions can affect the accuracy of macrobending loss test results. In the test of product validation and field application, single wavelength light source and optical power meter were often used. How to judge whether there is effect existing and how to remove the Whispering gallery modes influence in the testing process has become the key to correctly test macrobending loss by light source and optical power meter. This paper introduces the method of eliminating Whispering gallery modes effect during the macrobending test under small bending radius by single wavelength light source and optical power meter.

  13. Quantum information transfer with nitrogen-vacancy centers coupled to a whispering-gallery microresonator

    CERN Document Server

    Li, Pengbo

    2010-01-01

    We propose an efficient scheme for the realization of quantum information transfer and entanglement with nitrogen-vacancy (NV) centers coupled to a high-Q microspherical resonator. We show that, based on the effective dipole-dipole interaction between the NV centers mediated by the whispering-gallery mode (WGM), quantum information can be transferred between the NV centers through Raman transitions combined with laser fields. This protocol may open up promising possibilities for quantum communications with the solid state cavity QED system.

  14. Tunable add-drop filter using an active whispering gallery mode microcavity

    CERN Document Server

    Monifi, Faraz; Yang, Lan

    2013-01-01

    An add-drop filter (ADF) fabricated using a whispering gallery mode resonator has different crosstalks for add and drop functions due to non-zero intrinsic losses of the resonator. Here, we show that introducing gain medium in the resonator and optically pumping it below the lasing threshold not only allows loss compensation to achieve similar and lower crosstalks but also tunability in bandwidth and add-drop efficiency. For an active ADF fabricated using an erbium-ytterbium co-doped microsphere, we achieved 24-fold enhancement in the intrinsic quality factor, 3.5-fold increase in drop efficiency, bandwidth tunability of 35 MHz and a crosstalk of only 2%.

  15. Vertically-coupled Whispering Gallery Mode Resonator Optical Waveguide, and Methods

    Science.gov (United States)

    Matsko, Andrey B. (Inventor); Savchenkov, Anatolly A. (Inventor); Matleki, Lute (Inventor)

    2007-01-01

    A vertically-coupled whispering gallery mode (WGM) resonator optical waveguide, a method of reducing a group velocity of light, and a method of making a waveguide are provided. The vertically-coupled WGM waveguide comprises a cylindrical rod portion having a round cross-section and an outer surface. First and second ring-shaped resonators are formed on the outer surface of the cylindrical rod portion and are spaced from each other along a longitudinal direction of the cylindrical rod. The first and second ringshaped resonators are capable of being coupled to each other by way an evanescent field formed in an interior of the cylindrical rod portion.

  16. Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

    CERN Document Server

    Lin, Guoping; Saleh, Khaldoun; Martinenghi, Romain; Beugnot, Jean-Charles; Sylvestre, Thibaut; Chembo, Yanne K

    2015-01-01

    We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

  17. Highly tunable low-threshold optical parametric oscillation in radially poled whispering gallery resonators

    CERN Document Server

    Beckmann, T; Steigerwald, H; Sturman, B; Haertle, D; Buse, K; Breunig, I

    2010-01-01

    Tunability of optical parametric oscillation in a radially structured whispering gallery resonator made of lithium niobate is investigated experimentally and theoretically. With a 1.04-\\mu m pump wave, the signal and idler waves are tuned from 1.78 to 2.5 \\mu m -- including the point of degeneracy -- by varying the temperature between 20 and 62{\\deg}C. A weak off-centering of the radial domain structure extends considerably the tuning capabilities. The oscillation threshold lies in the mW-power range.

  18. Whispering gallery mode photoemission from self-assembled poly-para-phenylenevinylene microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Kushida, Soh; Yamamoto, Yohei [Division of Materials Science and Tsukuba Research Center for Interdisciplinary Materials Science (TIMS), Faculty of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan); Braam, Daniel; Lorke, Axel [Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstraße 1, Duisburg, D-47048 (Germany)

    2015-12-31

    Poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMOPPV) self-assembles to form well-defined spheres with several micrometers in diameter upon addition of a methanol vapor into a chloroform solution of MDMOPPV. The single sphere of MDMOPPV with 5.7 µm diameter exhibits whispering gallery mode (WGM) photoemission upon excitation with focused laser beam. The periodic emission lines are characterized by transverse electric and magnetic WGMs, and Q-factor reaches ∼345 at the highest.

  19. Highly efficient generation of single-mode photon pairs using a crystalline whispering gallery mode resonator

    CERN Document Server

    Förtsch, Michael; Fürst, Josef U; Strekalov, Dmitry; Gerrits, Thomas; Stevens, Martin J; Sedlmeir, Florian; Schwefel, Harald G L; Nam, Sae Woo; Leuchs, Gerd; Marquardt, Christoph

    2014-01-01

    We report a highly efficient source of narrow-band photon pairs based on parametric down-conversion in a crystalline whispering gallery mode resonator. Remarkably, each photon of a pair is strictly emitted into a single spatial and temporal mode, as witnessed by Glaubers autocorrelation function. We explore the phase-matching conditions in spherical geometries, and determine the requirements of the single-mode operation. Understanding these conditions has allowed us to experimentally demonstrate a single-mode pair-detection rate of $0.97 \\cdot 10^6$ pairs/s per mW pump power per 20 MHz bandwidth without the need of additional filter cavities.

  20. Coupler for coupling gyrotron whispering gallery mode RF into HE11 waveguide

    Science.gov (United States)

    Neilson, Jeffrey M

    2015-02-24

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  1. Electrodynamical Light Trapping Using Whispering-Gallery Resonances in Hyperbolic Cavities

    Directory of Open Access Journals (Sweden)

    Chihhui Wu

    2014-04-01

    Full Text Available We theoretically study spherical cavities composed of hyperbolic metamaterials with indefinite permittivity tensors. Such cavities are capable of electrodynamically confining fields with deep subwavelength cavity sizes. The supported resonant modes are analogous to the whispering-gallery modes found in dielectric microcavities with much larger physical sizes. Because of the nature of electrodynamical confinement, these hyperbolic metamaterial cavities exhibit quality factors higher than predicted in the electrostatic limit. In addition, confining electromagnetic fields into the small cavities results in an extremely high photonic local density of states.

  2. Whispering-gallery-mode microdisk lasers produced by femtosecond laser direct writing.

    Science.gov (United States)

    Ku, Jin-Feng; Chen, Qi-Dai; Zhang, Ran; Sun, Hong-Bo

    2011-08-01

    We report in this Letter fabrication of whispering-gallery-mode microdisk lasers by femtosecond laser direct writing of dye-doped resins. Not only is well-defined disk shape upheld on an inverted cone-shaped supporter, but the disk also exhibits significant lasing actions characteristic of an abrupt increase of light output and the significant narrowing of the spectral lines when the threshold is approached. This work shows that the laser micronanofabrication technology is not only applicable to passive micro-optical components, but also it may play an important role in fabrication of active optoelectronic devices and their integrated photonic circuits.

  3. Wavelength shift in a whispering gallery microdisk due to bacterial sensing: A theoretical approach

    Directory of Open Access Journals (Sweden)

    Hala Ghali

    2017-04-01

    Full Text Available Whispering gallery mode microcavities have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Binding of a biomolecule to the surface of a microresonator will increase its path length, leading to a shift in the resonance frequency according to the reactive sensing principle. In this paper, we develop a theoretical expression that will link the reactive shift to the bacteria and microdisk parameters and help quantify the number of bacteria that bind to the surface of a 200μm-diameter silica microdisk.

  4. High-Q silk fibroin whispering gallery microresonator on a flexible chip

    CERN Document Server

    Xu, Linhua; Zhao, Guangming; Liu, Zhiwen; Yang, Lan

    2016-01-01

    We have experimentally demonstrated on-chip all silk fibroin whispering gallery mode microresonator by using the molding and solution casting technique. The quality factors of the fabricated silk protein microresonators are up to 0.9*10^5. A high-sensitivity thermal sensor was realized in this silk fibroin microtoroid with the sensitivity of 1.17 nm/K, 8 times higher than previous WGM resonantor based thermal sensors. This opens the way to fabricate the biodegradable and biocompatible protein based microresonators on a flexible chip for biophotonics applications in vivo.

  5. Spatiotemporal Lugiato-Lefever formalism for Kerr-comb generation in whispering-gallery-mode resonators

    Science.gov (United States)

    Chembo, Yanne K.; Menyuk, Curtis R.

    2013-05-01

    We demonstrate that frequency (Kerr) comb generation in whispering-gallery-mode resonators can be modeled by a variant of the Lugiato-Lefever equation that includes higher-order dispersion and nonlinearity. This spatiotemporal model allows us to explore pulse formation in which a large number of modes interact cooperatively. Pulse formation is shown to play a critical role in comb generation, and we find conditions under which single pulses (dissipative solitons) and multiple pulses (rolls) form. We show that a broadband comb is the spectral signature of a dissipative soliton, and we also show that these solitons can be obtained by using a weak anomalous dispersion and subcritical pumping.

  6. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Science.gov (United States)

    Abramov, Arnold; Kostikov, Alexander

    2017-03-01

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder.

  7. Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators

    CERN Document Server

    Yang, Yong; Ward, Jonathan; Chormaic, Síle Nic

    2015-01-01

    Coupled-mode induced transparency is realized in a single microbubble whispering gallery mode resonator. Using aerostatic tuning, we find that the pressure induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference and this is confirmed by experiments. A transparency spectrum is obtained when a first order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.

  8. Dark-field imaging as a non-invasive method for characterization of whispering gallery modes in microdisk cavities

    CERN Document Server

    Baranov, D A; Shishkin, I I; Samusev, A K; Belov, P A; Bogdanov, A A

    2016-01-01

    Whispering gallery mode microdisk cavities fabricated by direct laser writing are studied using dark-field imaging and spectroscopy in the visible spectral range. {Dark-field imaging allows us to directly visualize the spatial intensity distribution of whispering gallery modes. We extract their azimuthal and radial mode indices from dark-field images, and find the axial mode number from the dispersion relation. The scattering spectrum obtained in the confocal arrangement provides information on the density of optical states in the resonator. The proposed technique is a simple non-invasive way to characterize the optical properties of microdisk cavities.

  9. Optical method for measuring thermal accommodation coefficients using a whispering-gallery microresonator

    Science.gov (United States)

    Ganta, D.; Dale, E. B.; Rezac, J. P.; Rosenberger, A. T.

    2011-08-01

    A novel optical method has been developed for the measurement of thermal accommodation coefficients in the temperature-jump regime. The temperature dependence of the resonant frequency of a fused-silica microresonator's whispering-gallery mode is used to measure the rate at which the microresonator comes into thermal equilibrium with the ambient gas. The thermal relaxation time is related to the thermal conductivity of the gas under some simplifying assumptions and measuring this time as a function of gas pressure determines the thermal accommodation coefficient. Using a low-power tunable diode laser of wavelength around 1570 nm to probe a microsphere's whispering-gallery mode through tapered-fiber coupling, we have measured the accommodation coefficients of air, helium, and nitrogen on fused silica at room temperature. In addition, by applying thin-film coatings to the microsphere's surface, we have demonstrated that accommodation coefficients can be measured for various gases on a wide range of modified surfaces using this method.

  10. Flow cytometer system for single-shot biosensing based on whispering gallery modes of fluorescent microspheres

    Science.gov (United States)

    Lessard, Reno; Rousseau-Cyr, Olivier; Charlebois, Maxime; Riviere, Christophe; Mermut, Ozzy; Allen, Claudine Nı.

    2013-02-01

    We report an innovative label-free biosensor based on statistical analysis of several whispering gallery modes spectral shifts in polystyrene fluorescent microspheres using a custom microflow cytometer. Whispering gallery modes analysis enables detection of nanometer-sized analytes showing promising possibilities for virus, bacteria and molecular detection. To demonstrate this, fluorophore-doped microspheres of the appropriate size parameter are mixed in an aqueous solution. Then, a syringe pump pushes the solution through a fiber optic flow cell where a laser beam illuminates the analysis area to excite the microspheres and their fluorescence is collected. This device provides a low-cost and user friendly solution that could enhance spectrum acquisition rates up to 5 spectra per second thanks to the considerable amount of microspheres flowing through the excitation area per unit time. Finally, the fluorescence spectra are statistically investigated using an instantaneous measurement of apparent refractive index algorithm to determine a reliable value for the refractive index of the environment since the exact radius of the microsphere scanned is unknown. This refractive index becomes an effective value for the local perturbation caused by inhomogeneities on the microsphere surface and hence, determines whether or not inhomogeneities, such as bacteria, are adsorbed by comparing to a control sample. Combining a flow cell with our detection algorithm, we reduce the period of a 50 microspheres experiment from 161 minutes to 14 minutes when the flow rate is 2000 µl/h and the microsphere concentration is 5 µsphere/µl.

  11. Raman-gain induced loss-compensation in whispering-gallery-microresonators and single-nanoparticle detection with whispering-gallery Raman-microlasers

    CERN Document Server

    Ozdemir, Sahin Kaya; Yang, Xu; Peng, Bo; Yilmaz, Huzeyfe; He, Lina; Monifi, Faraz; Long, Gui Lu; Yang, Lan

    2014-01-01

    Recently optical whispering-gallery-mode resonators (WGMRs) have emerged as promising platforms to achieve label-free detection of nanoscale objects and to reach single molecule sensitivity. The ultimate detection performance of WGMRs are limited by energy dissipation in the material they are fabricated from. Up to date, to improve detection limit, either rare-earth ions are doped into the WGMR to compensate losses or plasmonic resonances are exploited for their superior field confinement. Here, we demonstrate, for the first time, enhanced detection of single-nanoparticle induced mode-splitting in a silica WGMR via Raman-gain assisted loss-compensation and WGM Raman lasing. Notably, we detected and counted individual dielectric nanoparticles down to a record low radius of 10 nm by monitoring a beatnote signal generated when split Raman lasing lines are heterodyne-mixed at a photodetector. This dopant-free scheme retains the inherited biocompatibility of silica, and could find widespread use for sensing in bio...

  12. Cavity ring-up spectroscopy for dissipative and dispersive sensing in a whispering gallery mode resonator

    CERN Document Server

    Yang, Yong; Kasumie, Sho; Ward, Jonathan M; Chormaic, Síle Nic

    2016-01-01

    In whispering gallery mode resonator sensing applications, the conventional way to detect a change in the parameter to be measured is by observing the steady state transmission spectrum through the coupling waveguide. Alternatively, cavity ring-up spectroscopy (CRUS) sensing can be achieved transiently. In this work, we investigate CRUS using coupled mode equations and find analytical solutions with a large spectral broadening approximation of the input pulse. The relationships between the frequency detuning, coupling gap and ring-up peak height are determined and experimentally verified using an ultrahigh \\textit{Q}-factor silica microsphere. This work shows that distinctive dispersive and dissipative transient sensing can be realised by simply measuring the peak height of the CRUS signal, which might improve the data collection rate.

  13. Yield enhancement in whispering gallery mode biosensors: microfluidics and optical forces

    CERN Document Server

    Khosla, Kiran; Knittel, Joachim; Bowen, Warwick P

    2010-01-01

    A microfluidic whispering gallery mode (WGM) biosensing system is proposed for enhanced delivery and detection of target molecules. A microtoroid resonator coupled to a tapered optical fiber is immersed within a microfluidic channel, and supplied with target molecules at various flow rates. We show through Monte Carlo simulations that the flow characteristics and resonantly enhanced optical forces of the sensor substantially improve both the sensing time and yield. When compared to a diffusion-limited sensing modality, the average time required to detect a single molecule is reduced from more than 100 minutes to less than 10 seconds, and the overall yield of the device is enhanced from less than 5% to a maximum of 70.6% for femtomolar concentrations of analyte.

  14. Origin of optical losses in gallium arsenide disk whispering gallery resonators

    CERN Document Server

    Parrain, David; Wang, Guillaume; Guha, Biswarup; Santos, Eduardo Gil; Lemaitre, Aristide; Senellart, Pascale; Leo, Giuseppe; Ducci, Sara; Favero, Ivan

    2015-01-01

    Whispering gallery modes in GaAs disk resonators reach half a million of optical quality factor. These high Qs remain still well below the ultimate design limit set by bending losses. Here we investigate the origin of residual optical dissipation in these devices. A Transmission Electron Microscope analysis is combined with an improved Volume Current Method to precisely quantify optical scattering losses by roughness and waviness of the structures, and gauge their importance relative to intrinsic material and radiation losses. The analysis also provides a qualitative description of the surface reconstruction layer, whose optical absorption is then revealed by comparing spectroscopy experiments in air and in different liquids. Other linear and nonlinear optical loss channels in the disks are evaluated likewise. Routes are given to further improve the performances of these miniature GaAs cavities.

  15. Study On Planar Whispering Gallery Dielectric Resonators; 2, A Multiple-Band Device

    CERN Document Server

    Annino, G; Martinelli, M

    2002-01-01

    The basic theory underlying the realization of simple multiple-band non-homogeneous dielectric resonators, whose spectral response is the overlap of single-resonator frequency bands, is developed exploiting a general approach discussed in the previous companion paper. The limit frequencies of the proposed devices, given only by the dielectric properties of the involved materials, can differ in principle by several decades. Experimental confirmations have been obtained on a composite structure built up with teflon and polyethylene; as predicted by the theory, the overall band includes frequencies which range about from 20 GHz to more than 400 GHz, when high frequency resonances are selectively excited. The localization of the higher frequency radiation between the positive steps of the dielectric constant, which is the basic properties of these non-homogeneous resonators, has been experimentally verified by mapping the electromagnetic field intensity. Possible applications of multiple-band Whispering Gallery d...

  16. Efficient single sideband microwave to optical conversion using an electro-optical whispering gallery mode resonator

    CERN Document Server

    Rueda, Alfredo; Collodo, Michele C; Vogl, Ulrich; Stiller, Birgit; Schunk, Gerhard; Strekalov, Dmitry V; Marquardt, Christoph; Fink, Johannes M; Painter, Oskar; Leuchs, Gerd; Schwefel, Harald G L

    2016-01-01

    Linking classical microwave electrical circuits to the optical telecommunication band is at the core of modern communication. Future quantum information networks will require coherent microwave-to-optical conversion to link electronic quantum processors and memories via low-loss optical telecommunication networks. Efficient conversion can be achieved with electro-optical modulators operating at the single microwave photon level. In the standard electro-optic modulation scheme this is impossible because both, up- and downconverted, sidebands are necessarily present. Here we demonstrate true single sideband up- or downconversion in a triply resonant whispering gallery mode resonator by explicitly addressing modes with asymmetric free spectral range. Compared to previous experiments, we show a three orders of magnitude improvement of the electro-optical conversion efficiency reaching 0.1% photon number conversion for a 10GHz microwave tone at 0.42mW of optical pump power. The presented scheme is fully compatible...

  17. Barium fluoride whispering-gallery-mode disk-resonator with one billion quality-factor

    CERN Document Server

    Lin, Guoping; Henriet, Rémi; Jacquot, Maxime; Chembo, Yanne K

    2015-01-01

    We demonstrate a monolithic optical whispering gallery mode resonator fabricated with barium fluoride (BaF$_2$) with an ultra-high quality ($Q$) factor above $10^9$ at $1550$ nm, and measured with both the linewidth and cavity-ring-down methods. Vertical scanning optical profilometry shows that the root mean square surface roughness of $2$ nm is achieved for our mm-size disk. To the best of our knowledge, we show for the first time that one billion $Q$-factor is achievable by precision polishing in relatively soft crystals with mohs hardness of ~$3$. We show that complex thermo-optical dynamics can take place in these resonators. Beside usual applications in nonlinear optics and microwave photonics, high energy particle scintillation detection utilizing monolithic BaF$_2$ resonators potentially becomes feasible.

  18. III-nitride tunable cup-cavities supporting quasi whispering gallery modes from ultraviolet to infrared

    Science.gov (United States)

    Shubina, T. V.; Pozina, G.; Jmerik, V. N.; Davydov, V. Yu.; Hemmingsson, C.; Andrianov, A. V.; Kazanov, D. R.; Ivanov, S. V.

    2015-12-01

    Rapidly developing nanophotonics needs microresonators for different spectral ranges, formed by chip-compatible technologies. In addition, the tunable ones are much in demand. Here, we present site-controlled III-nitride monocrystal cup-cavities grown by molecular beam epitaxy. The cup-cavities can operate from ultraviolet to near-infrared, supporting quasi whispering gallery modes up to room temperature. Besides, their energies are identical in large ’ripened’ crystals. In these cavities, the refractive index variation near an absorption edge causes the remarkable effect of mode switching, which is accompanied by the spatial redistribution of electric field intensity with concentration of light into a subwavelength volume. Our results shed light on the mode behavior in semiconductor cavities and open the way for single-growth-run manufacturing the devices comprising an active region and a cavity with tunable mode frequencies.

  19. Dielectric tuning and coupling of whispering gallery modes using an anisotropic prism

    CERN Document Server

    Foreman, Matthew R; Schwefel, Harald G L; Leuchs, Gerd

    2016-01-01

    Optical whispering gallery mode (WGM) resonators are a powerful and versatile tool used in many branches of science. Fine tuning of the central frequency and line width of individual resonances is however desirable in a number of applications including frequency conversion, optical communications and efficient light-matter coupling. To this end we present a detailed theoretical analysis of dielectric tuning of WGMs supported in axisymmetric resonators. Using the Bethe-Schwinger equation and adopting an angular spectrum field representation we study the resonance shift and mode broadening of high $Q$ WGMs when a planar dielectric substrate is brought close to the resonator. Particular focus is given to use of a uniaxial substrate with an arbitrarily aligned optic axis. Competing red and blue resonance shifts ($\\sim 30$ MHz), deriving from generation of a near field material polarisation and back action from the radiation continuum respectively, are found. Anomalous resonance shifts can hence be observed depend...

  20. Whispering gallery mode single nano-particle detection and sizing: the validity of the dipole approximation

    CERN Document Server

    Foreman, Matthew R; Treasurer, Eshan; Lopez, Jehovani; Arnold, Stephen

    2016-01-01

    Interactions between whispering gallery modes (WGMs) and small nanoparticles are commonly modelled by treating the particle as a point dipole scatterer. This approach is assumed to be accurate as long as the nanoparticle radius, $a$, is small compared to the WGM wavelength $\\lambda$. In this article, however, we show that the large field gradients associated with the evanescent decay of a WGM causes the dipole theory to significantly underestimate the interaction strength, and hence induced WGM resonance shift, even for particles as small as $a\\sim \\lambda/10$. To mitigate this issue we employ a renormalized Born approximation to more accurately determine nanoparticle induced resonance shifts and hence enable improved particle sizing. The domain of validity of this approximation is investigated and supporting experimental results are presented.

  1. Visible Photoluminescence from Cubic (3C) Silicon Carbide Microdisks Coupled to High Quality Whispering Gallery Modes

    CERN Document Server

    Radulaski, Marina; Müller, Kai; Lagoudakis, Konstantinos G; Zhang, Jingyuan Linda; Buckley, Sonia; Kelaita, Yousif A; Alassaad, Kassem; Ferro, Gabriel; Vučković, Jelena

    2014-01-01

    We present the design, fabrication and characterization of cubic (3C) silicon carbide microdisk resonators with high quality factor modes at visible and near infrared wavelengths (600 - 950 nm). Whispering gallery modes with quality factors as high as 2,300 and corresponding mode volumes V ~ 2 ({\\lambda}/n)^3 are measured using laser scanning confocal microscopy at room temperature. We obtain excellent correspondence between transverse-magnetic (TM) and transverse-electric (TE) polarized resonances simulated using Finite Difference Time Domain (FDTD) method and those observed in experiment. These structures based on ensembles of optically active impurities in 3C-SiC resonators could play an important role in diverse applications of nonlinear and quantum photonics, including low power optical switching and quantum memories.

  2. Spatiotemporal Model for Kerr Comb Generation in Whispering Gallery Mode Resonators

    CERN Document Server

    Chembo, Yanne K

    2012-01-01

    We establish an exact partial differential equation to model Kerr comb generation in whispering-gallery mode resonators. This equation is a variant of the Lugiato-Lefever equation that includes higher-order dispersion and nonlinearity. This spatio-temporal model, whose main variable is the total intracavity field, is significantly more suitable than the modal expansion approach for the theoretical understanding and the numerical simulation of wide-span combs. It allows us to explore pulse formation in which a large number of modes interact cooperatively. This versatile approach can be straightforwardly extended to include higher-order dispersion, as well as other phenomena like Raman, Brillouin and Rayleigh scattering. We demonstrate for the first time that when the dispersion is anomalous, Kerr comb generation can arise as the spectral signature of dissipative cavity solitons, leading to wide-span combs with low pumping.

  3. Soliton Formation in Whispering-Gallery-Mode Resonators via Input Phase Modulation

    CERN Document Server

    Taheri, Hossein; Wiesenfeld, Kurt; Adibi, Ali

    2014-01-01

    We propose a method for soliton formation in whispering-gallery-mode (WGM) resonators through input phase modulation. Our numerical simulations of a variant of the Lugiato-Lefever equation suggest that modulating the input phase at a frequency equal to the resonator free-spectral-range and at modest modulation depths provides a deterministic route towards soliton formation in WGM resonators without undergoing a chaotic phase. We show that the generated solitonic state is sustained when the modulation is turned off adiabatically. Our results support parametric seeding as a powerful means of control, besides input pump power and pump-resonance detuning, over frequency comb generation in WGM resonators. Our findings also help pave the path towards ultra-short pulse formation on a chip.

  4. Microtorus: a high-finesse microcavity with whispering-gallery modes.

    Science.gov (United States)

    Ilchenko, V S; Gorodetsky, M L; Yao, X S; Maleki, L

    2001-03-01

    We demonstrate a 165-mu;m oblate spheroidal microcavity with a free spectral range of 383.7 GHz (3.06 nm), a resonance bandwidth of 23 MHz (quality factor Q approximately 10(7)) at 1550 nm, and finesse F>/=10(4) . The highly oblate spheroidal dielectric microcavity combines a very high Q factor, typical of microspheres, with a vastly reduced number of excited whispering-gallery modes (by 2 orders of magnitude). The very large free spectral range in this novel microcavity-a few hundred gigahertz instead of a few gigahertz as in typical microspheres-is desirable for applications in spectral analysis, narrow-linewidth optical and rf oscillators, and cavity QED.

  5. Optical sum-frequency generation in a whispering-gallery-mode resonator

    Science.gov (United States)

    Strekalov, Dmitry V.; Kowligy, Abijith S.; Huang, Yu-Ping; Kumar, Prem

    2014-05-01

    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.

  6. Phase noise of whispering gallery photonic hyper-parametric microwave oscillators.

    Science.gov (United States)

    Savchenkov, Anatoliy A; Rubiola, Enrico; Matsko, Andrey B; Ilchenko, Vladimir S; Maleki, Lute

    2008-03-17

    We report on the experimental study of phase noise properties of a high frequency photonic microwave oscillator based on four wave mixing in calcium fluoride whispering gallery mode resonators. Specifically, the oscillator generates approximately 8.5 GHz signals with -120 dBc/Hz at 100 kHz from the carrier. The floor of the phase noise is limited by the shot noise of the signal received at the photodetector. We argue that the performance of the oscillator can be significantly improved if one uses extremely high finesse resonators, increases the input optical power, supersaturates the oscillator, and suppresses the residual stimulated Raman scattering in the resonator. We also disclose a method of extremely sensitive measurement of the integral dispersion of millimeter scale dielectric resonators.

  7. Refractometric sensor based on whispering-gallery modes of thin capillarie.

    Science.gov (United States)

    Zamora, Vanessa; Díez, Antonio; Andrés, Miguel V; Gimeno, Benito

    2007-09-17

    Whispering-gallery modes resonances of submicron wall thickness capillaries exhibit very large wavelength shifts as a function of the refractive index of the medium that fills the inside. The sensitivity to refractive index changes is larger than in other optical microcavities as microspheres, microdisks and microrings. The outer surface where total internal reflection takes place remains always in air, enabling the measure of refractive index values higher than the refractive index of the capillary material. The fabrication of capillaries with submicron wall thickness has required the development of a specific technique. A refractometer with a response higher than 390 nm per refractive index unit is demonstrated. These sensors are readily compatible with microfluidic systems.

  8. Phase-locking transition in Raman combs generated with whispering gallery mode resonators.

    Science.gov (United States)

    Lin, Guoping; Chembo, Yanne K

    2016-08-15

    We investigate the mechanisms leading to phase locking in Raman optical frequency combs generated with ultrahigh Q crystalline whispering gallery mode disk resonators. We show that several regimes can be triggered depending on the pumping conditions, such as single-frequency Raman lasing, multimode operation involving more than one family of cavity eigenmodes, and Kerr-assisted Raman frequency comb generation. The phase locking and coherence of the combs are experimentally monitored through the measurement of beat signal spectra. These phase-locked combs, which feature high coherence and wide spectral spans, are obtained with pump powers in the range of a few tens of mW. In particular, Raman frequency combs with multiple free-spectral range spacings are reported, and the measured beat signal in the microwave domain features a 3 dB linewidth smaller than 50 Hz, thereby indicating phase locking.

  9. An ultra-narrow-band optical filter based on whispering-gallery-mode hybrid-microsphere-cavity

    Science.gov (United States)

    Wan, Hongdan; Zhu, Haohan; Liu, Linqian; Xu, Ji; Wang, Jin

    2016-10-01

    We demonstrate an ultra-narrow-band mode-selection method based on a hybrid-microsphere-cavity which consists of a coated silica microsphere. Optical field distribution and narrow-band transmission spectrum of the whispering gallery modes (WGM) are investigated by finite-difference time-domain method. WGM transmission spectra are measured for microsphere and tapered fibers with different diameters. A high refractive index layer coated on the microsphere-cavity make the Q factor increased, the transmission spectrum bandwidth compressed and the side-mode suppression ratio increased. Parameters of the hybrid-microsphere-cavity, namely, the coated shell thickness and its refractive index are optimized under different excitation light source as to investigate the whispering-gallery-modes' transmission spectrum. The 3dB bandwidth of the proposed filter can be less than MHz which will have great potential for applications in all-optical sensing and communication systems.

  10. High-Q MgF$_2$ whispering gallery mode resonators for refractometric sensing in aqueous environment

    CERN Document Server

    Sedlmeir, Florian; Leuchs, Gerd; Schwefel, Harald G L

    2014-01-01

    We present our experiments on refractometric sensing with ultrahigh-Q, crystalline, birefringent magnesium fluoride (MgF$_2$) whispering gallery mode resonators. The difference to fused silica which is most commonly used for sensing experiments is the small refractive index of MgF$_2$ which is very close to that of water. Compared to fused silica this leads to more than 50% longer evanescent fields and a 4.25 times larger sensitivity. Moreover the birefringence amplifies the sensitivity difference between TM and TE type modes which will enhance sensing experiments based on difference frequency measurements. We estimate the performance of our resonators and compare them with fused silica theoretically and present experimental data showing the interferometrically measured evanescent decay and the sensitivity of mm-sized MgF$_2$ whispering gallery mode resonators immersed in water. They show reasonable agreement with the developed theory. Furthermore, we observe stable Q factors in water well above $1 \\times 10^...

  11. Near-infrared single-photon spectroscopy of a whispering gallery mode resonator using energy-resolving transition edge sensors

    CERN Document Server

    Förtsch, Michael; Stevens, Martin J; Strekalov, Dmitry; Schunk, Gerhard; Fürst, Josef U; Vogl, Ulrich; Sedlmeir, Florian; Schwefel, Harald G L; Leuchs, Gerd; Nam, Sae Woo; Marquardt, Christoph

    2014-01-01

    We demonstrate a method to perform spectroscopy of near-infrared single photons without the need of dispersive elements. This method is based on a photon energy resolving transition edge sensor and is applied for the characterization of widely wavelength tunable narrow-band single photons emitted from a crystalline whispering gallery mode resonator. We measure the emission wavelength of the generated signal and idler photons with an uncertainty of up to 2 nm.

  12. Macroscopic Center-of-mass Cooling using Whispering Gallery Mode Resonances

    CERN Document Server

    Li, Ying Lia; Barker, P F

    2015-01-01

    We demonstrate simultaneous center-of-mass cooling of two coupled oscillators, consisting of a microsphere-cantilever and a tapered optical fiber. Excitation of a whispering gallery mode (WGM) of the microsphere, via the evanescent field of the taper, provides a transduction signal that continuously monitors the relative motion between these two microgram objects with a sensitivity of 3\\,pm. The cavity enhanced optical dipole force is used to provide feedback damping on the motion of the micron-diameter taper, whereas a piezo stack is used to damp the motion of the much larger (up to $ 180\\,\\mu$m in diameter), heavier (up to $1.5\\times 10^{-7}\\,$kg) and stiffer microsphere-cantilever. In each feedback scheme multiple mechanical modes of each oscillator can be cooled, and mode temperatures below 10\\,K are reached for the dominant mode, consistent with limits determined by the measurement noise of our system. This indicates stabilization on the $10^{-12}$ m level and is the first demonstration of using WGM reso...

  13. Method for predicting whispering gallery mode spectra of active spherical microresonators

    CERN Document Server

    Hall, Jonathan M M; Henderson, Matthew R; Francois, Alexandre; Reynolds, Tess; Riesen, Nicolas; Monro, Tanya M

    2014-01-01

    A full three-dimensional Finite-Difference Time-Domain (FDTD)-based toolkit is developed to simulate the whispering gallery modes of a microsphere in the vicinity of a dipole source, placed on the surface. This provides a guide for experiments that rely on coupling to active microspheres. The resultant spectra are compared to those of analytic models used in the field. In contrast to the analytic models, the FDTD method is able to collect flux from an arbitrary collection region, such as a disk-shaped region, analogous to an optical fibre. The flux collection time may also be altered to access transient phenomena that may not appear at long collection times. The customisability of the technique allows one to consider a variety of mode excitation scenarios, such as refractive index inhomogeneity in the material, and different resonator shapes, such as shells and ellipsoids. The coupling efficiency to specific modes within wavelength regions can thus be optimized, preselecting the desired optical properties pri...

  14. Using whispering gallery mode micro lasers for biosensing within undiluted serum

    Science.gov (United States)

    Reynolds, Tess; François, Alexandre; Riesen, Nicolas; Turvey, Michelle E.; Nicholls, Stephen J.; Hoffmann, Peter; Monro, Tanya M.

    2016-11-01

    Although whispering gallery mode (WGM) biosensors have shown tremendous potential, they are still yet to find practical use as biomedical diagnostic tools. This is primarily due to the nature of the interrogation mechanism itself which relies on indirect measurement of the binding of a specific biomolecule onto the sensor through the associated refractive index change. Since nonspecific binding cannot be differentiated from the specific interaction of interest, this can result in a high rate of false positive readings when the detection is performed in complex biological samples. Here we show that this inherent limitation can be solved using a relatively simple approach. This approach involves the development of a self-referenced biosensor consisting of two almost identically sized dye-doped polystyrene microspheres placed on adjacent holes at the tip of a suspended core optical fiber. Here self-referenced biosensing is demonstrated with the detection of Neutravidin in undiluted human serum samples. The fiber allows remote excitation and collection of the WGMs of the microspheres in a dip sensing setting. By taking advantage of surface functionalization techniques, one microsphere acts as a dynamic reference, compensating for nonspecific binding events, while the other microsphere is functionalized to detect the specific interaction. The almost identical size allows the two spheres to have virtually identical refractive index sensitivity and surface area. This ensures their responses to nonspecific binding and environmental changes are almost identical, whereby any specific changes such as binding events, can be monitored via the relative movement between the two sets of WGM peaks.

  15. Formation of whispering gallery modes by scattering of an electromagnetic plane wave by two cylinders

    Energy Technology Data Exchange (ETDEWEB)

    Abramov, Arnold, E-mail: qulaser@gmail.com [Kuang-Chi Institute of Advanced Technology, Shenzhen, 518057 (China); Kostikov, Alexander [Donbass State Engineering Academy, 84303, Kramatorsk, Donetsk (Ukraine)

    2017-03-26

    We report the effect of scattering of electromagnetic plane waves by two cylinders on whispering gallery mode (WGM) formation in a cylinder. WGM can occur because of the presence of additional cylinder scatterers at specific location, while WGMs can only form in a single cylinder for specific cylinder radius and/or wavelength values, the matching accuracy required would be much greater than that required in our model for the additional cylinders locations. Analysis of the general solution to the problem showed that the effect can be explained by the interference of waves scattered by additional cylinders and incident on the main cylinder. - Highlights: • We consider scattering of electromagnetic plane waves by two cylinders. • WGMs occur because of the presence of additional cylinder at specific location. • The accuracy for the locations is much less than required for specific values of single cylinder. • The interference of waves scattered by additional cylinders and incident on the main is responsible for the effect.

  16. [Review on label-free optical bio-sensing technology based on whisper-gallery-mode].

    Science.gov (United States)

    Jiang, Jun-feng; Liu, Tie-gen; Li, Hai-wei; Hui, Rong-qing; Liu, Kuni; Zhang, Yi-mo

    2010-11-01

    Optical biosensors are becoming an important tool for drug research and life science, and the label-free optical biosensor based on whisper-gallery-mode (WGM) is reviewed in the present paper. The WGM-based sensors are categorized into three types according to the microcavity structure. The biosensor using microsphere got extensive research because of high quality factor, and its response to protein, virus, and bacteria had been studied. The models based on single photon resonant state and perturbation theory were established. The biosensor using microdisk was proposed early since it can make use of mature lithography technology; however, the quality factor was increased greatly only after the thermal reflow process was introduced and single molecule measurement was then realized. The biosensor using microring has simpler mode structure and materials such as polymer, silicon nitride and silicon-on-insulator had been used for sensor fabrication. As a 3-dimension expansion, sensor using microtube can combine the optical channel and fluidic channel, which attracting more and more attention.

  17. Real-Time Detection of Staphylococcus Aureus Using Whispering Gallery Mode Optical Microdisks

    Directory of Open Access Journals (Sweden)

    Hala Ghali

    2016-05-01

    Full Text Available Whispering Gallery Mode (WGM microresonators have recently been studied as a means to achieve real-time label-free detection of biological targets such as virus particles, specific DNA sequences, or proteins. Due to their high quality (Q factors, WGM resonators can be highly sensitive. A biosensor also needs to be selective, requiring proper functionalization of its surface with the appropriate ligand that will attach the biomolecule of interest. In this paper, WGM microdisks are used as biosensors for detection of Staphylococcus aureus. The microdisks are functionalized with LysK, a phage protein specific for staphylococci at the genus level. A binding event on the surface shifts the resonance peak of the microdisk resonator towards longer wavelengths. This reactive shift can be used to estimate the surface density of bacteria that bind to the surface of the resonator. The limit of detection of a microdisk with a Q-factor around 104 is on the order of 5 pg/mL, corresponding to 20 cells. No binding of Escherichia coli to the resonators is seen, supporting the specificity of the functionalization scheme.

  18. Integrating Nanostructured Artificial Receptors with Whispering Gallery Mode Optical Microresonators via Inorganic Molecular Imprinting Techniques.

    Science.gov (United States)

    Hammond, G Denise; Vojta, Adam L; Grant, Sheila A; Hunt, Heather K

    2016-06-15

    The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound of interest. However, many environmental pollutants do not have corresponding biorecognition elements. Fortunately, biomimetic chemistries, such as molecular imprinting, allow for the design of artificial receptors with very high selectivity for the target. Here, we perform a proof-of-concept study to show how artificial receptors may be created from inorganic silanes using the molecular imprinting technique and paired with high-sensitivity transducers without loss of device performance. Silica microsphere Whispering Gallery Mode optical microresonators are coated with a silica thin film templated by a small fluorescent dye, fluorescein isothiocyanate, which serves as our model target. Oxygen plasma degradation and solvent extraction of the template are compared. Extracted optical devices are interacted with the template molecule to confirm successful sorption of the template. Surface characterization is accomplished via fluorescence and optical microscopy, ellipsometry, optical profilometry, and contact angle measurements. The quality factors of the devices are measured to evaluate the impact of the coating on device sensitivity. The resulting devices show uniform surface coating with no microstructural damage with Q factors above 10⁶. This is the first report demonstrating the integration of these devices with molecular imprinting techniques, and could lead to new routes to biosensor creation for environmental monitoring.

  19. Integrating Nanostructured Artificial Receptors with Whispering Gallery Mode Optical Microresonators via Inorganic Molecular Imprinting Techniques

    Directory of Open Access Journals (Sweden)

    G. Denise Hammond

    2016-06-01

    Full Text Available The creation of label-free biosensors capable of accurately detecting trace contaminants, particularly small organic molecules, is of significant interest for applications in environmental monitoring. This is achieved by pairing a high-sensitivity signal transducer with a biorecognition element that imparts selectivity towards the compound of interest. However, many environmental pollutants do not have corresponding biorecognition elements. Fortunately, biomimetic chemistries, such as molecular imprinting, allow for the design of artificial receptors with very high selectivity for the target. Here, we perform a proof-of-concept study to show how artificial receptors may be created from inorganic silanes using the molecular imprinting technique and paired with high-sensitivity transducers without loss of device performance. Silica microsphere Whispering Gallery Mode optical microresonators are coated with a silica thin film templated by a small fluorescent dye, fluorescein isothiocyanate, which serves as our model target. Oxygen plasma degradation and solvent extraction of the template are compared. Extracted optical devices are interacted with the template molecule to confirm successful sorption of the template. Surface characterization is accomplished via fluorescence and optical microscopy, ellipsometry, optical profilometry, and contact angle measurements. The quality factors of the devices are measured to evaluate the impact of the coating on device sensitivity. The resulting devices show uniform surface coating with no microstructural damage with Q factors above 106. This is the first report demonstrating the integration of these devices with molecular imprinting techniques, and could lead to new routes to biosensor creation for environmental monitoring.

  20. Superpersistent currents and whispering gallery modes in relativistic quantum chaotic systems.

    Science.gov (United States)

    Xu, Hongya; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso

    2015-03-11

    Persistent currents (PCs), one of the most intriguing manifestations of the Aharonov-Bohm (AB) effect, are known to vanish for Schrödinger particles in the presence of random scatterings, e.g., due to classical chaos. But would this still be the case for Dirac fermions? Addressing this question is of significant value due to the tremendous recent interest in two-dimensional Dirac materials. We investigate relativistic quantum AB rings threaded by a magnetic flux and find that PCs are extremely robust. Even for highly asymmetric rings that host fully developed classical chaos, the amplitudes of PCs are of the same order of magnitude as those for integrable rings, henceforth the term superpersistent currents (SPCs). A striking finding is that the SPCs can be attributed to a robust type of relativistic quantum states, i.e., Dirac whispering gallery modes (WGMs) that carry large angular momenta and travel along the boundaries. We propose an experimental scheme using topological insulators to observe and characterize Dirac WGMs and SPCs, and speculate that these features can potentially be the base for a new class of relativistic qubit systems. Our discovery of WGMs in relativistic quantum systems is remarkable because, although WGMs are common in photonic systems, they are relatively rare in electronic systems.

  1. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Directory of Open Access Journals (Sweden)

    T. Siegle

    2017-09-01

    Full Text Available Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  2. Nonreciprocal light transmission in parity-time-symmetric whispering-gallery microcavities

    CERN Document Server

    Peng, Bo; Lei, Fuchuan; Monifi, Faraz; Gianfreda, Mariagiovanna; Long, Gui Lu; Fan, Shanhui; Nori, Franco; Bender, Carl M; Yang, Lan

    2013-01-01

    Optical systems combining balanced loss and gain profiles provide a unique platform to implement classical analogues of quantum systems described by non-Hermitian parity-time- (PT-) symmetric Hamiltonians and to originate new synthetic materials with novel properties. To date, experimental works on PT-symmetric optical systems have been limited to waveguides in which resonances do not play a role. Here we report the first demonstration of PT-symmetry breaking in optical resonator systems by using two directly coupled on-chip optical whispering-gallery-mode (WGM) microtoroid silica resonators. Gain in one of the resonators is provided by optically pumping Erbium (Er3+) ions embedded in the silica matrix; the other resonator exhibits passive loss. The coupling strength between the resonators is adjusted by using nanopositioning stages to tune their distance. We have observed reciprocal behavior of the PT-symmetric system in the linear regime, as well as a transition to nonreciprocity in the PT symmetry-breaking...

  3. Robust Whispering-Gallery-Mode Microbubble Lasers from Colloidal Quantum Dots.

    Science.gov (United States)

    Wang, Yue; Ta, Van Duong; Leck, Kheng Swee; Tan, Beng Hau Ian; Wang, Zeng; He, Tingchao; Ohl, Claus-Dieter; Demir, Hilmi Volkan; Sun, Handong

    2017-03-21

    Microlasers hold great promise for the development of photonics and optoelectronics. Among the discovered optical gain materials, colloidal quantum dots (CQDs) have been recognized as the most appealing candidate due to the facile emission tunability and solution processability. However, to date, it is still challenging to develop CQD-based microlasers with low cost yet high performance. Moreover, the poor long-term stability of CQDs remains to be the most critical issue, which may block their laser aspirations. Herein, we developed a unique but generic approach to forming a novel type of a whispering-gallery-mode (WGM) microbubble laser from the hybrid CQD/poly(methyl methacrylate) (PMMA) nanocomposites. The formation mechanism of the microbubbles was unraveled by recording the drying process of the nanocomposite droplets. Interestingly, these microbubbles naturally serve as the high-quality WGM laser resonators. By simply changing the CQDs, the lasing emission can be tuned across the whole visible spectral range. Importantly, these microbubble lasers exhibit unprecedented long-term stability (over one year), sufficient for practical applications. As a proof-of-concept, the potential of water vapor sensing was demonstrated. Our results represent a significant advance in microlasers based on the advantageous CQDs and may offer new possibilities for photonics and optoelectronics.

  4. Optical signal processing and tracking of whispering gallery modes in real-time for sensing applications

    Science.gov (United States)

    Ali, Amir R.; Afifi, Amr N.; Taha, Hazem

    2017-05-01

    A novel approach for tracking of whispering gallery modes (WGM) in real-time for dielectric cavities used in sensing application is presented in this paper. Real-time tracking for the shifts of the WGM can be used to measure the physical quantity of interest precisely, under high repetition rates. The tracking algorithm is based on cross-correlation signal processing technique which has been proved to be accurate in WGM shifts detection. In order to achieve portability, the aforementioned real-time algorithm is implemented using a single-board re-configurable input-output hardware. The hardware platform used combines a real-time processor and a field programmable gate array (FPGA), it also allows for data exchange between them. The tracking algorithm's accuracy and real-time behavior is verified by preforming simulations based on experiments conducted on the dielectric cavity, where the cavity is used as a force sensor measuring mechanical compression. The light from a laser diode is tuned with rates up to 10 kHz and then tangentially coupled into the cavity to excite the WGM. Results show that shifts of the WGM are tracked by the algorithm providing real-time force readings.

  5. Whispering Gallery Mode Resonances from Ge Micro-Disks on Suspended Beams

    Directory of Open Access Journals (Sweden)

    Abdelrahman Zaher Al-Attili

    2015-05-01

    Full Text Available Ge is considered to be one of the most promising materials for realizing full monolithic integration of a light source on a silicon (Si photonic chip. Tensile-strain is required to convert Ge into an optical gain material and to reduce the pumping required for population inversion. Several methods of strain application to Ge are proposed in literature, of which the use of free-standing beams fabricated by micro-electro-mechanical systems (MEMS processes are capable of delivering very high strain values. However, it is challenging to make an optical cavity within free-standing Ge beams, and here, we demonstrate the fabrication of a simple cavity while imposing tensile strain by suspension using Ge-On-Insulator (GOI wafers. Ge micro-disks are made on top of suspended SiO$_{2}$ beams by partially removing the supporting Si substrate. According to Raman spectroscopy, a slight tensile strain was applied to the Ge disks through the bending of the SiO2 beams. Whispering-Gallery-Mode (WGM resonances were observed from a disk with a diameter of 3um, consistent with the finite-domain time-difference simulations. The quality (Q factor was 192, and upon increasing the pumping power, the Q-factor was degraded due to the red-shift of Ge direct-gap absorption edge caused by heating.

  6. Optimally Coherent Kerr Combs Generated with Crystalline Whispering Gallery Mode Resonators for Ultrahigh Capacity Fiber Communications

    Science.gov (United States)

    Pfeifle, Joerg; Coillet, Aurélien; Henriet, Rémi; Saleh, Khaldoun; Schindler, Philipp; Weimann, Claudius; Freude, Wolfgang; Balakireva, Irina V.; Larger, Laurent; Koos, Christian; Chembo, Yanne K.

    2015-03-01

    Optical Kerr frequency combs are known to be effective coherent multiwavelength sources for ultrahigh capacity fiber communications. These combs are the frequency-domain counterparts of a wide variety of spatiotemporal dissipative structures, such as cavity solitons, chaos, or Turing patterns (rolls). In this Letter, we demonstrate that Turing patterns, which correspond to the so-called primary combs in the spectral domain, are optimally coherent in the sense that for the same pump power they provide the most robust carriers for coherent data transmission in fiber communications using advanced modulation formats. Our model is based on a stochastic Lugiato-Lefever equation which accounts for laser pump frequency jitter and amplified spontaneous emission noise induced by the erbium-doped fiber amplifier. Using crystalline whispering-gallery-mode resonators with quality factor Q ˜109 for the comb generation, we show that when the noise is accounted for, the coherence of a primary comb is significantly higher than the coherence of their solitonic or chaotic counterparts for the same pump power. In order to confirm this theoretical finding, we perform an optical fiber transmission experiment using advanced modulation formats, and we show that the coherence of the primary comb is high enough to enable data transmission of up to 144 Gbit /s per comb line, the highest value achieved with a Kerr comb so far. This performance evidences that compact crystalline photonic systems have the potential to play a key role in a new generation of coherent fiber communication networks, alongside fully integrated systems.

  7. Drag detection and identification by whispering gallery mode optical resonance based sensor

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

    2013-06-01

    Experimental data on optical resonance spectra of whispering gallery modes of dielectric microspheres in antibiotic solutions under varied in wide range concentration are represented. Optical resonance was demonstrated could be detected at a laser power of less than 1 microwatt. Several antibiotics of different generations: Amoxicillin, Azithromycin, Cephazolin, Chloramphenicol, Levofloxacin, Lincomicin Benzylpenicillin, Riphampicon both in deionized water and physiological solution had been used for measurements. Both spectral shift and the structure of resonance spectra were of specific interest in this investigation. Drag identification has been performed by developed multilayer perceptron network. The network topology was designed included: a number of the hidden layers of multilayered perceptron, a number of neurons in each of layers, a method of training of a neural network, activation functions of layers, type and size of a deviation of the received values from required values. For a network training the method of the back propagation error in various modifications has been used. Input vectors correspond to 6 classes of biological substances under investigation. The result of classification was considered as positive when each of the region, representing a certain substance in a space: relative spectral shift of an optical resonance maxima - relative efficiency of excitation of WGM, was singly connected. It was demonstrated that the approach described in the paper can be a promising platform for the development of sensitive, lab-on-chip type sensors that can be used as an express diagnostic tools for different drugs and instrumentation for proteomics, genomics, drug discovery, and membrane studies.

  8. Biochemical component identification by light scattering techniques in whispering gallery mode optical resonance based sensor

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Saetchnikov, Anton V.; Schweiger, Gustav; Ostendorf, Andreas

    2014-03-01

    Experimental data on detection and identification of variety of biochemical agents, such as proteins (albumin, interferon, C reactive protein), microelements (Na+, Ca+), antibiotic of different generations, in both single and multi component solutions under varied in wide range concentration are represented. Analysis has been performed on the light scattering parameters of whispering gallery mode (WGM) optical resonance based sensor with dielectric microspheres from glass and PMMA as sensitive elements fixed by spin - coating techniques in adhesive layer on the surface of substrate or directly on the coupling element. Sensitive layer was integrated into developed fluidic cell with a digital syringe. Light from tuneable laser strict focusing on and scattered by the single microsphere was detected by a CMOS camera. The image was filtered for noise reduction and integrated on two coordinates for evaluation of integrated energy of a measured signal. As the entrance data following signal parameters were used: relative (to a free spectral range) spectral shift of frequency of WGM optical resonance in microsphere and relative efficiency of WGM excitation obtained within a free spectral range which depended on both type and concentration of investigated agents. Multiplexing on parameters and components has been realized using spatial and spectral parameters of scattered by microsphere light with developed data processing. Biochemical component classification and identification of agents under investigation has been performed by network analysis techniques based on probabilistic network and multilayer perceptron. Developed approach is demonstrated to be applicable both for single agent and for multi component biochemical analysis.

  9. Split-disk micro-lasers: Tunable whispering gallery mode cavities

    Science.gov (United States)

    Siegle, T.; Remmel, M.; Krämmer, S.; Kalt, H.

    2017-09-01

    Optical micro-cavities of various types have emerged as promising photonic structures, for both the investigation of fundamental science in cavity quantum electrodynamics and simultaneously for various applications, e.g., lasers, filters, or modulators. In either branch a demand for adjustable and tunable photonic devices becomes apparent, which has been mainly based on the modification of the refractive index of the micro-resonators so far. In this paper, we report on a novel type of whispering gallery mode resonator where resonance tuning is achieved by modification of the configuration. This is realized by polymeric split-disks consisting of opposing half-disks with an intermediate air gap. Functionality of the split-disk concept and its figures of merit like low-threshold lasing are demonstrated for laser dye-doped split-disks fabricated by electron beam lithography on Si substrates. Reversible resonance tuning is achieved for split-disks structured onto elastomeric substrates by direct laser writing. The gap width and hence the resonance wavelength can be well-controlled by mechanically stretching the elastomer and exploiting the lateral shrinkage of the substrate. We demonstrate a broad spectral tunability of laser modes by more than three times the free spectral range. These cavities have the potential to form a key element of flexible and tunable photonic circuits based on polymers.

  10. Ultrahigh Q whispering gallery mode electro-optic resonators on a silicon photonic chip.

    Science.gov (United States)

    Soltani, Mohammad; Ilchenko, Vladimir; Matsko, Andrey; Savchenkov, Anatoliy; Schlafer, John; Ryan, Colm; Maleki, Lute

    2016-09-15

    Crystalline whispering gallery mode (WGM) electro-optic resonators made of LiNbO3 and LiTaO3 are critical for a wide range of applications in nonlinear and quantum optics, as well as RF photonics, due to their remarkably ultrahigh Q(>108) and large electro-optic coefficient. Achieving efficient coupling of these resonators to planar on-chip optical waveguides is essential for any high-yield and robust practical applications. However, it has been very challenging to demonstrate such coupling while preserving the ultrahigh Q properties of the resonators. Here, we show how the silicon photonic platform can overcome this long-standing challenge. Silicon waveguides with appropriate designs enable efficient and strong coupling to these WGM electro-optic resonators. We discuss various integration architectures of these resonators onto a silicon chip and experimentally demonstrate critical coupling of a planar Si waveguide and an ultrahigh QLiTaO3 resonator (Q∼108). Our results show a promising path for widespread and practical applications of these resonators on a silicon photonic platform.

  11. Classification of antibiotics by neural network analysis of optical resonance data of whispering gallery modes in dielectric microspheres

    Science.gov (United States)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav; Ostendorf, Andreas

    2012-04-01

    A novel emerging technique for the label-free analysis of nanoparticles and biomolecules in liquid fluids using optical micro cavity resonance of whispering-gallery-type modes is being developed.A scheme based on polymer microspheres fixed by adhesive on the evanescence wave coupling element has been used. We demonstrated that the only spectral shift can't be used for identification of biological agents by developed approach. So neural network classifier for biological agents and micro/nano particles classification has been developed. The developed technique is the following. While tuning the laser wavelength images were recorded as avi-file. All sequences were broken into single frames and the location of the resonance was allocated in each frame. The image was filtered for noise reduction and integrated over two coordinates for evaluation of integrated energy of a measured signal. As input data normalized resonance shift of whispering-gallery modes and the relative efficiency of whispering-gallery modes excitation were used. Other parameters such as polarization of excited light, "center of gravity" of a resonance spectra etc. are also tested as input data for probabilistic neural network. After network designing and training we estimated the accuracy of classification. The classification of antibiotics such as penicillin and cephasolin have been performed with the accuracy of not less 97 %. Developed techniques can be used for lab-on-chip sensor based diagnostic tools as for identification of different biological molecules, e.g. proteins, oligonucleotides, oligosaccharides, lipids, small molecules, viral particles, cells and for dynamics of a delivery of medicines to bodies.

  12. An optical wall shear stress sensor based on whispering gallery modes of dielectric microspheres

    Science.gov (United States)

    Ayaz, Ulas Kemal

    In recent years, whispering gallery modes (WGM) of dielectric resonators have received significant attention. Based on this phenomenon, many applications have been proposed ranging from spectroscopy [1], micro-cavity laser technology [2] and optical communications (switching [3], filtering [4] and wavelength division and multiplexing [5]). WGM phenomenon have also been exploited in several sensor concepts such as protein adsorption [6,7], trace gas detection [8], impurity detection in liquids [9], structural health monitoring of composite materials [10], detection of electric fields [11], magnetic fields [12, 13] and temperature [14, 15] as well as mechanical sensing, such as pressure [16] and force [17,18]. A remarkable feature of the WGMs of dielectric microspheres is that they can exhibit extremely high quality factors (Q -factors). In literature, Q-factors as high as ˜10 10 have been reported [19]. In sensor applications, Q-factors determine the resolution of the sensor. Since WGMs of dielectric microspheres exhibit such high Q values, proposed WGM based sensors have extremely good sensing resolutions. In this dissertation, a WGM based wall shear stress sensor that is capable of measuring the shear stress directly is presented. The proposed sensor's feasibility is studied both analytically and experimentally. The experimental study included sensor development, fabrication, calibration, frequency response, dynamic range and proof of concept. The sensor showed that it has potential to measure the shear stress in a wide range of Reynolds numbers. Finally, the sensor is tested in a real flow environment to provide the first direct shear stress measurement in a real flow.

  13. Bio-optical sensor for brain activity measurement based on whispering gallery modes

    Science.gov (United States)

    Ali, Amir R.; Massoud, Yasmin M.

    2017-05-01

    In this paper, a high-resolution bio-optical sensor is developed for brain activity measurement. The aim is to develop an optical sensor with enough sensitivity to detect small electric field perturbations caused by neuronal action potential. The sensing element is a polymeric dielectric micro-resonator fabricated in a spherical shape with a few hundred microns in diameter. They are made of optical quality polymers that are soft which make them mechanically compatible with tissue. The sensors are attached to or embedded in optical fibers which serve as input/output conduits for the sensors. Hundreds or even thousands of spheres can be attached to a single fiber to detect and transmit signals at different locations. The high quality factor for the optical resonator makes it significantly used in such bio-medical applications. The sensing phenomenon is based on whispering gallery modes (WGM) shifts of the optical sensor. To mimic the brain signals, the spherical resonator is immersed in a homogeneous electrical field that is created by applying potential difference across two metallic plates. One of the plates has a variable voltage while the volt on the other plate kept fixed. Any small perturbations of the potential difference (voltage) lead to change in the electric field intensity. In turn the sensor morphology will be affected due to the change in the electrostriction force acting on it causing change in its WGM. By tracking these WGM shift on the transmission spectrum, the induced potential difference (voltage change) could be measured. Results of a mathematical model simulation agree well with the preliminary experiments. Also, the results show that the brain activity could be measured using this principle.

  14. Broadband optical absorbance spectroscopy using a whispering gallery mode microsphere resonator

    Science.gov (United States)

    Westcott, Sarah L.; Zhang, Jiangquan; Shelton, Robert K.; Bruce, Nellie M. K.; Gupta, Sachin; Keen, Steven L.; Tillman, Jeremy W.; Wald, Lara B.; Strecker, Brian N.; Rosenberger, A. T.; Davidson, Roy R.; Chen, Wei; Donovan, Kevin G.; Hryniewicz, John V.

    2008-03-01

    We demonstrate the ability to excite and monitor many whispering gallery modes (WGMs) of a microsphere resonator simultaneously in order to make broadband optical absorbance measurements. The 340μm diameter microsphere is placed in a microfluidic channel. A hemispherical prism is used for coupling the WGMs into and out of the microsphere. The flat surface of the prism seals the microfluidic channel. The slight nonsphericity in the microsphere results in coupling to precessed modes whose emission is spatially separated from the reflected excitation light. The evanescent fields of the light trapped in WGMs interact with the surrounding environment. The change in transmission observed in the precessed modes is used to determine the absorbance of the surrounding environment. In contrast to our broadband optical absorbance measurements, previous WGM sensors have used only a single narrow mode to measure properties such as refractive index. With the microfluidic cell, we have measured the absorbance of solutions of dyes (lissamine green B, sunset yellow, orange G, and methylene blue), aromatic molecules (benzylamine and benzoic acid), and biological molecules (tryptophan, phenylalanine, tyrosine, and o-phospho-L-tyrosine) at visible and ultraviolet wavelengths. The microsphere surface was reacted with organosilane molecules to attach octadecyl groups, amino groups, and fluorogroups to the surface. Both electrostatic and hydrophobic interactions were observed between the analytes and the microsphere surface, as indicated by changes in the measured effective pathlength with different organosilanes. For a given analyte and coated microsphere, the pathlength measurement was repeatable within a few percent. Methylene blue dye had a very strong interaction with the surface and pathlengths of several centimeters were measured. Choosing an appropriate surface coating to interact with a specific analyte should result in the highest sensitivity detection.

  15. Whispering gallery mode bio-sensor for label-free detection of single molecules: thermo-optic vs. reactive mechanism.

    Science.gov (United States)

    Arnold, S; Shopova, S I; Holler, S

    2010-01-04

    Thermo-optic and reactive mechanisms for label-free sensing of bio-particles are compared theoretically for Whispering Gallery Mode (WGM) resonators (sphere, toroid) formed from silica and stimulated into a first order equatorial mode. Although it has been expected that a thermo-optic mechanism should "greatly enhance" wavelength shift signals [A.M. Armani et al, Science 317, 783-787 (2007)] accompanying protein binding on a silica WGM cavity having high Q (10(8)), for a combination of wavelength (680 nm), drive power (1 mW), and cavity size (43 microm radius), our calculations find no such enhancement. The possible reasons for this disparity are discussed.

  16. THz Pyro-Optical Detector Based on LiNbO3 Whispering Gallery Mode Microdisc Resonator

    Science.gov (United States)

    Cosci, Alessandro; Cerminara, Matteo; Nunzi Conti, Gualtiero; Soria, Silvia; Righini, Giancarlo C.; Pelli, Stefano

    2017-01-01

    This study analyzes the capabilities of a LiNbO3 whispering gallery mode microdisc resonator as a potential bolometer detector in the THz range. The resonator is theoretically characterized in the stationary regime by its thermo-optic and thermal coefficients. Considering a Q-factor of 107, a minimum detectable power of 20 μW was evaluated, three orders of magnitude above its noise equivalent power. This value opens up the feasibility of exploiting LiNbO3 disc resonators as sensitive room-temperature detectors in the THz range. PMID:28134857

  17. Single-Photon Scattering by a Three-level System Interacting with a Whispering-Gallery Resonator Coupled to One-Dimensional Waveguide

    Institute of Scientific and Technical Information of China (English)

    CHENG Mu-Tian; SONG Yan-Yan; LUO Ya-Qin; ZHAO Guang-xing

    2011-01-01

    We investigate theoretically the single-photon scattering by a A-type three-level system interacting with a whispering-gallery-type resonator which is coupled to a one-dimensional waveguide by full quantum-mechanical approach,The single-photon transmission amplitude and reflection amplitude are obtained exactly via real-space approach. The single-photon transport properties controlling by classic optical field are discussed. The critical coupling condition in the coupled waveguide-whispering-gallery resonator-atom with three-level system is also analyzed.

  18. Microsensors based on a whispering gallery mode in AlGaN microdisks undercut by hydrogen-environment thermal etching.

    Science.gov (United States)

    Kouno, Tetsuya; Sakai, Masaru; Takeshima, Hoshi; Suzuki, Sho; Kikuchi, Akihiko; Kishino, Katsumi; Hara, Kazuhiko

    2017-04-20

    AlGaN microdisks were fabricated via a top-down process using electron-beam lithography, inductively coupled plasma reactive-ion etching, and hydrogen-environment thermal etching from commercial epitaxial wafers with a 100-300 nm thick AlGaN layer grown on a c-plane GaN layer by metal-organic chemical vapor deposition. The hydrogen-environment thermal etching performed well in undercutting the AlGaN microdisks owing to the selective etching for the GaN layer. The AlGaN microdisks acted as the whispering gallery mode (WGM) optical microresonators, exhibiting sharp resonant peaks in room temperature photoluminescence spectra. The evanescent component of the whispering gallery mode (WGM) is influenced by the ambient condition of the microdisk, resulting in the shift of the resonant peaks. The phenomenon is considered to be used for microsensors. Using the WGM in the AlGaN microdisks, we demonstrated microsensors and a microsensor system, which can potentially be used to evaluate biological and chemical actions in a microscale area in real time.

  19. Whispering gallery states of neutrons and anti-hydrogen atoms and their applications to fundamental and surface physics

    Science.gov (United States)

    Nesvizhevsky, Valery

    2013-03-01

    The `whispering gallery' effect has been known since ancient times for sound waves in air, later in water and more recently for a broad range of electromagnetic waves: radio, optics, Roentgen and so on. It is intensively used and explored due to its numerous crucial applications. It consists of wave localization near a curved reflecting surface and is expected for waves of various natures, for instance, for neutrons and (anti)atoms. For (anti)matter waves, it includes a new feature: a massive particle is settled in quantum states, with parameters depending on its mass. In this talk, we present the first observation of the quantum whispering-gallery effect for matter particles (cold neutrons) 1-2. This phenomenon provides an example of an exactly solvable problem analogous to the `quantum bouncer'; it is complementary to recently discovered gravitational quantum states of neutrons3. These two phenomena provide a direct demonstration of the weak equivalence principle for a massive particle in a quantum state. Deeply bound long-living states are weakly sensitive to surface potential; highly excited short-living states are very sensitive to the wall nuclear potential shape. Therefore, they are a promising tool for studying fundamental neutron-matter interactions, quantum neutron optics and surface physics effects. Analogous phenomena could be measured with atoms and anti-atoms 4-5.

  20. Controllable Optical Switch in a One-Dimensional Resonator Waveguide Coupled to a Whispering-Gallery Resonator

    Institute of Scientific and Technical Information of China (English)

    LANG Jia-Hong

    2011-01-01

    Single photon transport properties in a one-dimensional array of coupled microcavities waveguide coupled to a whispering-gallery resonator interacting with a A-type system are theoretically investigated.The calculations reveal that the transport properties of single photons with arbitrary energy can be controlled by varying the Rabi frequency and detuning the control optical field.This phenomenon can be used for controllable optical switching.Single photon transport properties in a onedimensional waveguide coupled to a two-level[1-10] or multi-level[11-17] system have been studied theoretically and experimentally for their potential applications in quantum information and all-optical devices.A coupled cavity array is considered as a one-dimensional waveguide and the single photon transport properties in such a system coupled to a two-level and multi-level system have been studied.%Single photon transport properties in a one-dimensional array of coupled microcavities waveguide coupled to a whispering-gallery resonator interacting with a A-type system are theoretically investigated. The calculations reveal that the transport properties of single photons with arbitrary energy can be controlled by varying the Rabi frequency and detuning the control optical field. This phenomenon can be used for controllable optical switching.

  1. Development of Whispering Gallery Mode Polymeric Micro-optical Electric Field Sensors

    Science.gov (United States)

    Ioppolo, Tindaro; Ötügen, Volkan; Ayaz, Ulas

    2013-01-01

    Optical modes of dielectric micro-cavities have received significant attention in recent years for their potential in a broad range of applications. The optical modes are frequently referred to as "whispering gallery modes" (WGM) or "morphology dependent resonances" (MDR) and exhibit high optical quality factors. Some proposed applications of micro-cavity optical resonators are in spectroscopy1, micro-cavity laser technology2, optical communications3-6 as well as sensor technology. The WGM-based sensor applications include those in biology7, trace gas detection8, and impurity detection in liquids9. Mechanical sensors based on microsphere resonators have also been proposed, including those for force10,11, pressure12, acceleration13 and wall shear stress14. In the present, we demonstrate a WGM-based electric field sensor, which builds on our previous studies15,16. A candidate application of this sensor is in the detection of neuronal action potential. The electric field sensor is based on polymeric multi-layered dielectric microspheres. The external electric field induces surface and body forces on the spheres (electrostriction effect) leading to elastic deformation. This change in the morphology of the spheres, leads to shifts in the WGM. The electric field-induced WGM shifts are interrogated by exciting the optical modes of the spheres by laser light. Light from a distributed feedback (DFB) laser (nominal wavelength of ~ 1.3 μm) is side-coupled into the microspheres using a tapered section of a single mode optical fiber. The base material of the spheres is polydimethylsiloxane (PDMS). Three microsphere geometries are used: (1) PDMS sphere with a 60:1 volumetric ratio of base-to-curing agent mixture, (2) multi layer sphere with 60:1 PDMS core, in order to increase the dielectric constant of the sphere, a middle layer of 60:1 PDMS that is mixed with varying amounts (2% to 10% by volume) of barium titanate and an outer layer of 60:1 PDMS and (3) solid silica sphere

  2. Thermo-Optical Tuning of Whispering Gallery Modes in Er:Yb Doped Glass Microspheres to Arbitrary Probe Wavelengths

    CERN Document Server

    Watkins, Amy; Chormaic, Síle Nic

    2012-01-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An Er:Yb co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F = 3 to 5P3/2 F' = 4 laser cooling transition of 85Rb. This is of particular interest for cavity QED-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  3. Selective excitation of Fabry-Perot or whispering-gallery mode-type lasing in GaN microrods

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Hyeonjun; Hyun, Jerome K.; Chung, Kunook; Oh, Hongseok; Yi, Gyu-Chul, E-mail: gcyi@snu.ac.kr [Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2014-11-17

    Lasing from long semiconductor nanorods is dictated by Fabry-Perot (FP) resonances whereas that from large-diameter microrods is determined by whispering gallery modes (WGMs). Lengths and diameters intermediate between the two systems represent an important size regime for photonics and electronics, but have not been studied in detail. Here, we report on the detection of FP and WGM lasing emissions from a single GaN microrod, and demonstrate the ability to switch between the two lasing mechanisms by translating the excitation beam along the microrod. The competition between FP and WGM-type lasing was studied by finite-difference time-domain simulation and statistical analysis by measuring microrods of various diameters. Finally, control over the relative lasing intensities originating from either FPs or WGMs was demonstrated by tuning the polarization of the emission.

  4. Detection and size measurement of individual hemozoin nanocrystals in aquatic environment using a whispering gallery mode resonator

    CERN Document Server

    Kim, Woosung; Zhu, Jiangang; Faraz, Monifi; Coban, Cevayir; Yang, Lan; 10.1364/OE.20.029426

    2013-01-01

    We, for the first time, report the detection and the size measurement of single nanoparticles (i.e. polystyrene) in aquatic environment using mode splitting in a whispering gallery mode (WGM) optical resonator, namely a microtoroid resonator. Using this method we achieved detecting and measuring individual synthetic hemozoin nanocrystals, which are a hemoglobin degradation by-product of malarial parasites, dispersed in a solution or in air. The results of size measurement in solution and in air agree with each other and with those obtained using scanning electron microscope and dynamic light scattering. Moreover, we compare the sensing capabilities of the degenerate (single resonance) and non-degenerate (split mode, doublet) operation regimes of the WGM resonator.

  5. Integrating a DNA Strand Displacement Reaction with a Whispering Gallery Mode Sensor for Label-Free Mercury (II) Ion Detection.

    Science.gov (United States)

    Wu, Fengchi; Wu, Yuqiang; Niu, Zhongwei; Vollmer, Frank

    2016-07-29

    Mercury is an extremely toxic chemical pollutant of our environment. It has attracted the world's attention due to its high mobility and the ease with which it accumulates in organisms. Sensitive devices and methods specific for detecting mercury ions are, hence, in great need. Here, we have integrated a DNA strand displacement reaction with a whispering gallery mode (WGM) sensor for demonstrating the detection of Hg(2+) ions. Our approach relies on the displacement of a DNA hairpin structure, which forms after the binding of mercury ions to an aptamer DNA sequence. The strand displacement reaction of the DNA aptamer provides highly specific and quantitative means for determining the mercury ion concentration on a label-free WGM sensor platform. Our approach also shows the possibility for manipulating the kinetics of a strand displacement reaction with specific ionic species.

  6. Frequency tuning of single photons from a whispering-gallery mode resonator to MHz-wide transitions

    DEFF Research Database (Denmark)

    Schunk, G.; Vogl, U.; Sedlmeir, F.

    2016-01-01

    Quantum repeaters rely on interfacing flying qubits with quantum memories. The most common implementations include a narrowband single photon matched in bandwidth and central frequency to an atomic system. Previously, we demonstrated the compatibility of our versatile source of heralded single...... photons, which is based on parametric down-conversion in a triply resonant whispering-gallery mode resonator, with alkaline transitions [Schunk et al., Optica 2015, 2, 773]. In this paper, we analyse our source in terms of phase matching, available wavelength-tuning mechanisms and applications...... to narrowband atomic systems. We resonantly address the D1 transitions of caesium and rubidium with this optical parametric oscillator pumped above its oscillation threshold. Below threshold, the efficient coupling of single photons to atomic transitions heralded by single telecom-band photons is demonstrated...

  7. Thermo-Optical Tuning of Whispering Gallery Modes in Erbium:Ytterbium Doped Glass Microspheres to Arbitrary Probe Wavelengths

    Science.gov (United States)

    Watkins, Amy; Ward, Jonathan; Chormaic, Síle Nic

    2012-05-01

    We present experimental results on an all-optical, thermally-assisted technique for broad range tuning of microsphere cavity resonance modes to arbitrary probe wavelengths. An erbium:ytterbium co-doped phosphate glass (Schott IOG-2) microsphere is pumped at 978 nm via the supporting stem and the heat generated by absorption of the pump light expands the cavity and changes the refractive index. This is a robust tuning method that decouples the pump from the probe and allows fine tuning of the microsphere's whispering gallery modes. Pump/probe experiments were performed to demonstrate thermo-optical tuning to specific probe wavelengths, including the 5S1/2 F= 3 to 5P3/2 F'= 4 laser cooling transition of rubidium-85. This is of particular interest for cavity quantum electrodynamics (QED)-type experiments, while the broad tuning range achievable is useful for integrated photonic devices, including sensors and modulators.

  8. Tunable waveguide and cavity in a phononic crystal plate by controlling whispering-gallery modes in hollow pillars

    DEFF Research Database (Denmark)

    Jin, Yabin; Fernez, Nicolas; Pennec, Yan;

    2016-01-01

    We investigate the properties of a phononic crystal plate with hollow pillars and introduce the existence of whispering-gallery modes (WGMs). We show that by tuning the inner radius of the hollow pillar, these modes can merge inside both Bragg and low frequency band gaps, deserving phononic crystal...... and acoustic metamaterial applications. These modes can be used as narrow pass bands for which the quality factor can be greatly enhanced by the introduction of an additional cylinder between the hollow cylinder and the plate. We discuss some functionalities of these confined WGM in both Bragg and low...... frequency gaps for wavelength division in multiplexer devices using heteroradii pillars introduced into waveguide and cavity structures....

  9. Frequency tuning of the whispering-gallery modes of silica microspheres for cavity quantum electrodynamics and spectroscopy.

    Science.gov (United States)

    von Klitzing, W; Long, R; Ilchenko, V S; Hare, J; Lefèvre-Seguin, V

    2001-02-01

    We have tuned the whispering-gallery modes of a fused-silica microresonator over nearly 1 nm at 800 nm, i.e., over half a free spectral range, or 10(6) linewidths of the resonator. This result has been achieved by use of a new method based on the stretching of a two-stem microsphere. We describe devices that will permit new cavity QED experiments with this high- Q optical resonator when it is desirable to optimize its coupling to emitters with given transition frequencies. The demonstrated tuning capability is compatible with both UHV and low-temperature operation, which should be useful for future experiments with laser-cooled atoms or single quantum dots.

  10. Light-controlled microwave whispering-gallery-mode quasi-optical resonators at 50W LED array illumination

    Directory of Open Access Journals (Sweden)

    V. B. Yurchenko

    2015-08-01

    Full Text Available We present experimental observations of light-controlled resonance effects in microwave whispering-gallery-mode quasi-optical dielectric-semiconductor disk resonators in the frequency band of 5 GHz to 20 GHz arising due to illumination from a light emitting diode (LED of 50W power range. We obtain huge enhancement of photo-sensitivity (growing with the resonator Q-factor that makes light-microwave interaction observable with an ordinary light (no laser at conventional brightness (like an office lighting in quasi-optical microwave structures at rather long (centimeter-scale wavelength. We also demonstrate non-conventional photo-response of Fano resonances when the light suppresses one group of resonances and enhances another group. The effects could be used for the optical control and quasi-optical switching of microwave propagation through either one or another frequency channel.

  11. Coupling of a single diamond nanocrystal to a whispering-gallery microcavity: Photon transport benefitting from Rayleigh scattering

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yongchun; Xiao Yunfeng; Li Beibei; Jiang Xuefeng; Li Yan; Gong Qihuang [State Key Lab for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China)

    2011-07-15

    We study the Rayleigh scattering induced by a diamond nanocrystal in a whispering-gallery-microcavity-waveguide coupling system and find that it plays a significant role in the photon transportation. On the one hand, this study provides insight into future solid-state cavity quantum electrodynamics aimed at understanding strong-coupling physics. On the other hand, benefitting from this Rayleigh scattering, effects such as dipole-induced transparency and strong photon antibunching can occur simultaneously. As a potential application, this system can function as a high-efficiency photon turnstile. In contrast to B. Dayan et al. [Science 319, 1062 (2008)], the photon turnstiles proposed here are almost immune to the nanocrystal's azimuthal position.

  12. Controlled self-assembly of organic composite microdisks for efficient output coupling of whispering-gallery-mode lasers.

    Science.gov (United States)

    Wei, Cong; Liu, Si-Yun; Zou, Chang-Ling; Liu, Yingying; Yao, Jiannian; Zhao, Yong Sheng

    2015-01-14

    Flexible microdisk whispering-gallery-mode (WGM) resonators with high quality factors were achieved through the controlled assembly of organic materials with an emulsion-solvent-evaporation method. The high material compatibility of the assembled microdisks enabled us to realize low-threshold WGM lasers by doping with organic dyes as gain media. Furthermore, the emulsion-assisted self-assembly provided a strategy for the one-step fabrication of microwire-waveguide-connected microdisk heterostructures, which can be utilized for the efficient output of the isotropic WGM lasers from the coupled waveguides. We hope that these results will pave an avenue for the construction of new types of flexible WGM-based components for photonic integration.

  13. Tailoring the plasmonic whispering gallery modes of a metal-coated resonator for potential application as a refractometric sensor.

    Science.gov (United States)

    Guo, Chang-Lei; Che, Kai-Jun; Gu, Guo-Qiang; Cai, Guo-Xiong; Cai, Zhi-Ping; Xu, Hui-Ying

    2015-02-20

    Plasmonic whispering gallery (WG) modes confined in metal-coated resonators are theoretically investigated by electromagnetic analyses. The resonance can be tuned from internal surface plasmonic WG modes to the hybrid state of the plasmonic mode by an introduced isolation layer. As the coated metal is reduced in size, the optical resonance is shifted out by the mode coupling of the internal and external surface plasmonic WG modes. Based on the optical leak of the plasmonic WG mode, the optical influences led by the surroundings with a variable refractive index are considered. Device performance criteria such as optical power leak, resonant wavelength shift, and threshold gain are studied. Full wave simulations are also employed and the results present good consistency with analytic solutions. The metal-coated resonator assisted by an active material is expected to provide promising performance as a refractometric sensor.

  14. Efficient analysis and design of low-loss whispering-gallery-mode coupled resonator optical waveguide bends

    CERN Document Server

    Pishko, Svetlana V; Benson, Trevor M; Boriskina, Svetlana V

    2007-01-01

    Waveguides composed of electromagnetically-coupled optical microcavities (coupled resonator optical waveguides or CROWs) can be used for light guiding, slowing and storage. In this paper, we present a two-dimensional analysis of finite-size straight and curved CROW sections based on a rigorous Muller boundary integral equations method. We study mechanisms of the coupling of whispering gallery (WG) modes and guiding light around bends in CROWs composed of both identical and size-mismatched microdisk resonators. Our accurate analysis reveals differences in WG modes coupling in the vicinity of bends in CROWs composed of optically-large and wavelength-scale microcavities. We propose and discuss possible ways to design low-loss CROW bends and to reduce bend losses. These include selecting specific bend angles depending on the azimuthal order of the WG mode and tuning the radius of the microdisk positioned at the CROW bend.

  15. Whispering-gallery-mode based CH3NH3PbBr3 perovskite microrod lasers with high quality factors

    CERN Document Server

    Wang, Kaiyang; Zhang, Chen; Sun, Wenzhao; Gu, Zhiyuan; Xiao, Shumin; Song, Qinghai

    2016-01-01

    Lead halide perovskite based micro- and nano- lasers have been widely studied in past two years. Due to their long carrier diffusion length and high external quantum efficiency, lead halide perovskites have been considered to have bright future in optoelectronic devices, especially in the "green gap" wavelength region. However, the quality (Q) factors of perovskite lasers are unspectacular compared to conventional microdisk lasers. The record value of full width at half maximum (FWHM) at threshold is still around 0.22 nm. Herein we synthesized solution-processed, single-crystalline CH3NH3PbBr3 perovskite microrods and studied their lasing actions. In contrast to entirely pumping a microrod on substrate, we partially excited the microrods that were hanging in the air. Consequently, single-mode or few-mode laser emissions have been successfully obtained from the whispering-gallery like diamond modes, which are confined by total internal reflection within the transverse plane. Owning to the better light confinem...

  16. Mathematical Model for Electric Field Sensor Based on Whispering Gallery Modes Using Navier’s Equation for Linear Elasticity

    Directory of Open Access Journals (Sweden)

    Amir R. Ali

    2017-01-01

    Full Text Available This paper presents and verifies the mathematical model of an electric field senor based on the whispering gallery mode (WGM. The sensing element is a dielectric microsphere, where the light is used to tune the optical modes of the microsphere. The light undergoes total internal reflection along the circumference of the sphere; then it experiences optical resonance. The WGM are monitored as sharp dips on the transmission spectrum. These modes are very sensitive to morphology changes of the sphere, such that, for every minute change in the sphere’s morphology, a shift in the transmission spectrum will happen and that is known as WGM shifts. Due to the electrostriction effect, the applied electric field will induce forces acting on the surface of the dielectric sphere. In turn, these forces will deform the sphere causing shifts in its WGM spectrum. The applied electric field can be obtained by calculating these shifts. Navier’s equation for linear elasticity is used to model the deformation of the sphere to find the WGM shift. The finite element numerical studies are performed to verify the introduced model and to study the behavior of the sensor at different values of microspheres’ Young’s modulus and dielectric constant. Furthermore, the sensitivity and resolution of the developed WGM electric filed sensor model will be presented in this paper.

  17. Frequency tuning of single photons from a whispering-gallery mode resonator to MHz-wide transitions

    Science.gov (United States)

    Schunk, G.; Vogl, U.; Sedlmeir, F.; Strekalov, D. V.; Otterpohl, A.; Averchenko, V.; Schwefel, H. G. L.; Leuchs, G.; Marquardt, Ch.

    2016-11-01

    Quantum repeaters rely on interfacing flying qubits with quantum memories. The most common implementations include a narrowband single photon matched in bandwidth and central frequency to an atomic system. Previously, we demonstrated the compatibility of our versatile source of heralded single photons, which is based on parametric down-conversion in a triply resonant whispering-gallery mode resonator, with alkaline transitions [Schunk et al., Optica 2015, 2, 773]. In this paper, we analyse our source in terms of phase matching, available wavelength-tuning mechanisms and applications to narrowband atomic systems. We resonantly address the D1 transitions of caesium and rubidium with this optical parametric oscillator pumped above its oscillation threshold. Below threshold, the efficient coupling of single photons to atomic transitions heralded by single telecom-band photons is demonstrated. Finally, we present an accurate analytical description of our observations. Providing the demonstrated flexibility in connecting various atomic transitions with telecom wavelengths, we show a promising approach to realize an essential building block for quantum repeaters.

  18. Toward Automatic Label-Free Whispering Gallery Modes Biodetection with a Quantum Dot-Coated Microsphere Population

    Science.gov (United States)

    Charlebois, M.; Paquet, A.; Verret, L. S.; Boissinot, K.; Boissinot, M.; Bergeron, M. G.; Allen, C. Nì.

    2010-03-01

    We explore a new calibration-free approach to biodetection based on whispering gallery modes (WGMs) without a reference measure and relative shifts. Thus, the requirement to keep track of the sensor position is removed, and a freely moving population of fluorophore-doped polystyrene microspheres can now fulfill this role of sensing resonator. Breaking free from fixed surface-based biosensing promotes adhesion between the microsphere sensors and the analytes since both can now be thoroughly mixed. The 70-nm-wide spectrum of green fluorescent microbeads allows us to monitor over 20 WGMs simultaneously without needing evanescent light coupling into the microspheres, hence enabling remote sensing. Since the exact radius of each microsphere is unknown a priori, it requires algorithmic analyses to obtain a reliable result for the refractive index of a solution. We first test our approach with different solutions of alcohol in water obtaining 3 × 10-4 precision on the refractive index at lower concentrations. Then, the solutions of bacterial spores in water yield clear evidence of biodetection in the statistical analysis of WGMs from 50 microspheres. To extend the fluorescence spectral range of our WGM sensors, we present preliminary results on coating microspheres with CdSe/ZnS quantum dots.

  19. Lasing mode regulation and single-mode realization in ZnO whispering gallery microcavities by the Vernier effect.

    Science.gov (United States)

    Wang, Y Y; Xu, C X; Jiang, M M; Li, J T; Dai, J; Lu, J F; Li, P L

    2016-10-07

    The wide direct bandgap and strong exciton binding energy of ZnO have inspired examinations of ultraviolet lasing over the previous decades. However, regulation of the lasing mode, especially the realization of single mode lasing, is still a challenge. In this study, a ZnO comb-like structure with an array of microrods was selected to design coupled whispering-gallery-mode cavities, wherein the naturally varied air-gap between the adjacent microrods created a flexible condition for optical field coupling without any complicated micromanipulation. Spectral behaviour of lasing and coupling interaction between coupled ZnO microrods were systematically investigated. By regulating the nano-scale inter-space of dual coupled microrods, stable single-mode lasing with a higher Q factor and lower threshold was obtained successfully based on the Vernier effect. The formation conditions and the mechanism of single-mode lasing derived from the coupled ZnO microrods were discussed in detail. It also demonstrated an approach to construct high quality single-mode lasing by tuning the diameters of the coupled ZnO microrods.

  20. Traceable 2D finite-element simulation of the whispering-gallery modes of axisymmetric electromagnetic resonators

    CERN Document Server

    Oxborrow, M

    2006-01-01

    This paper explains how a popular, commercially-available software package for solving partial-differential-equations (PDEs), as based on the finite-element method (FEM), can be configured to calculate, efficiently, the frequencies and fields of the whispering-gallery (WG) modes of axisymmetric dielectric resonators. The approach is traceable; it exploits the PDE-solver's ability to accept the definition of solutions to Maxwell's equations in so-called `weak form'. Associated expressions and methods for estimating a WG mode's volume, filling factor(s) and, in the case of closed(open) resonators, its wall(radiation) loss, are provided. As no transverse approximation is imposed, the approach remains accurate even for quasi-transverse magnetic/electric modes of low, finite azimuthal mode order. The approach's generality and utility are demonstrated by modeling several non-trivial structures: (i) two different optical microcavities [one toroidal made of silica, the other an AlGaAs microdisk]; (ii) a 3rd-order sap...

  1. Optical multistability and Fano line-shape control via mode coupling in whispering-gallery-mode microresonator optomechanics

    Science.gov (United States)

    Zhang, Suzhen; Li, Jiahua; Yu, Rong; Wang, Wei; Wu, Ying

    2017-01-01

    We study a three-mode (i.e., a clockwise mode, a counterclockwise mode, and a mechanical mode) coherent coupling regime of the optical whispering-gallery-mode (WGM) microresonator optomechanical system by considering a pair of counterpropagating modes in a general case. The WGM microresonator is coherently driven by a strong control laser field and a relatively weak probe laser field via a tapered fiber. The system parameters utilized to explore this process correspond to experimentally demonstrated values in the WGM microresonator optomechanical systems. By properly adjusting the coupling rate of these two counterpropagating modes in the WGM microresonator, the steady-state displacement behaviors of the mechanical oscillation and the normalized power transmission and reflection spectra of the output fields are analyzed in detail. It is found that the mode coupling plays a crucial role in rich line-shape structures. Some interesting phenomena of the system, including optical multistability and sharp asymmetric Fano-shape optomechanically induced transparency (OMIT), can be generated with a large degree of control and tunability. Our obtained results in this study can be used for designing efficient all-optical switching and high-sensitivity sensor.

  2. Reduction of mode Q-factor due to coupling between fundamental and first order whispering-gallery modes in coupled microdisks

    Institute of Scientific and Technical Information of China (English)

    LI Jun-jie; WANG Jia-xian; HUANG Yong-zhen

    2007-01-01

    The mode characteristics for twin coupled microdisks are investigated by fmite-difference time-domain technique. In the coupled microdisks, the same order whispering-gallery (WG) modes can form coupled modes with split mode wavelengths.We find that the coupled fundamental and first order WG modes can have anticrossing mode coupling as their wavelengths approach the same value in some case, which prevents the cross of the coupled mode wavelengths. The anticrossing mode coupling greatly reduces the coupled mode Q-factor, because the coupled mode field distribution transfers between the fundamental and the first order WG modes.

  3. Low-threshold whispering-gallery-mode microlasers fabricated in a Nd: glass substrate by three-dimensional femtosecond laser micromachining

    CERN Document Server

    Lin, Jintian; Song, Jiangxin; Zeng, Bin; He, Fei; Xu, Huailiang; Sugioka, Koji; Fang, Wei; Cheng, Ya

    2013-01-01

    We report on fabrication of whispering-gallery-mode microlasers in a Nd:glass chip by femtosecond laser three-dimensional (3D) micromachining. Main fabrication procedures include the fabrication of freestanding microdisks supported by thin pillars by femtosecond laser ablation of the glass substrate immersed in water, followed by CO2 laser annealing for surface smoothing. Lasing is observed at a pump threshold as low as ~69 {\\mu}W at room temperature with a continuous-wave laser diode operating at 780nm. This technique allows for fabrication of microcavities of high quality factors in various dielectric materials such as glasses and crystals.

  4. Gyrotron whispering gallery mode coupler with a mode conversion reflector for exciting a circular symmetric uniform phase RF beam in a corrugated waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Neilson, Jeffrey M.

    2017-07-25

    A cylindrical waveguide with a mode converter transforms a whispering gallery mode from a gyrotron cylindrical waveguide with a helical cut launch edge to a quasi-Gaussian beam suitable for conveyance through a corrugated waveguide. This quasi-Gaussian beam is radiated away from the waveguide using a spiral cut launch edge, which is in close proximity to a first mode converting reflector. The first mode converting reflector is coupled to a second mode converting reflector which provides an output free-space HE11 mode wave suitable for direct coupling into a corrugated waveguide. The radiated beam produced at the output of the second mode converting reflector is substantially circular.

  5. Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

    Science.gov (United States)

    Asano, M.; Özdemir, Ş. K.; Chen, W.; Ikuta, R.; Yang, L.; Imoto, N.; Yamamoto, T.

    2016-05-01

    We report controllable manipulation of slow and fast light in a whispering-gallery-mode microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

  6. Controlling slow and fast light and dynamic pulse-splitting with tunable optical gain in a whispering-gallery-mode microcavity

    CERN Document Server

    Asano, Motoki; Chen, Weijian; Ikuta, Rikizo; Yang, Lan; Imoto, Nobuyuki; Yamamoto, Takashi

    2016-01-01

    We report controllable manipulation of slow and fast light in a whispering-gallery-mode (WGM) microtoroid resonator fabricated from Erbium (Er3+) doped silica. We observe continuous transition of the coupling between the fiber-taper waveguide and the microresonator from undercoupling to critical coupling and then to overcoupling regimes by increasing the pump power even though the spatial distance between the resonator and the waveguide was kept fixed. This, in turn, enables switching from fast to slow light and vice versa just by increasing the optical gain. An enhancement of delay of two-fold over the passive silica resonator (no optical gain) was observed in the slow light regime. Moreover, we show dynamic pulse splitting and its control in slow/fast light systems using optical gain.

  7. On the dispersion management of fluorite whispering-gallery mode resonators for Kerr optical frequency comb generation in the telecom and mid-infrared range

    CERN Document Server

    Lin, Guoping

    2015-01-01

    Optical whispering gallery mode (WGM) resonators have been very attracting platforms for versatile Kerr frequency comb generations. We report a systematic study on the material dispersion of various optical materials that are capable of supporting quality factors above $10^9$. Using an analytical approximation of WGM resonant frequencies in disk resonators, we investigate the effect of the geometry and transverse mode order on the total group-velocity dispersion ($GVD$). We demonstrate that the major radii and the radial mode indices play an important role in tailoring the $GVD$ of WGM resonators. In particular, our study shows that in WGM disk-resonators, the polar families of modes have very similar $GVD$, while the radial families of modes feature dispersion values that can differ by up to several orders of magnitude. The effect of these giant dispersion shifts are experimentally evidenced in Kerr comb generation with magnesium fluoride. From a more general perspective, this critical feature enables to pus...

  8. Finite element simulation of a perturbed axial-symmetric whispering-gallery mode and its use for intensity enhancement with a nanoparticle coupled to a microtoroid

    CERN Document Server

    Kaplan, Alex; Carmon, Tal; Kozlov, Maxim; Cohen, Oren; Bartal, Guy; Schwefel, Harald G L

    2013-01-01

    We present an optical mode solver for a whispering gallery resonator coupled to an adjacent arbitrary shaped nano-particle that breaks the axial symmetry of the resonator. Such a hybrid resonator-nanoparticle is similar to what was recently used for bio-detection and for field enhancement. We demonstrate our solver by parametrically studying a toroid-nanoplasmonic device and get the optimal nano-plasmonic size for maximal enhancement. We investigate cases near a plasmonic resonance as well as far from a plasmonic resonance. Unlike common plasmons that typically benefit from working near their resonance, here working far from plasmonic resonance provides comparable performance. This is because the plasmonic resonance enhancement is accompanied by cavity quality degradation through plasmonic absorption.

  9. Observation of second-order hyper-Raman generation in LiNbO3 whispering-gallery mode disk resonators

    CERN Document Server

    Simons, Matt T

    2011-01-01

    In this manuscript we report experimental demonstration of nonlinear frequency conversion at several optical frequencies in a whispering-gallery mode resonator (WGMR). Due to the enhancement of nonlinear interactions inside a WGMR, interaction of a 1064 nm pump field with a LiNbO3 disk produced a weak, but measurable non-phase matched 532 nm second harmonic field at room temperature (>100C below the phase-matching temperature), for pump powers of a few tens of mW. For higher pump powers, we observed the generation of four additional fields at 545 nm, 559 nm, 573 nm, and 587 nm. The relative spectral shift between two consecutive fields corresponds to a 455 cm^-1 vibrational mode in LiNbO3 crystal. Our preliminary analysis indicates that these fields are the result of a multi-phonon hyper-Raman scattering, in which two photons of the pump field are converted into one photon of a higher-frequency field and one or several optical phonons.

  10. Observation of second-order hyper-Raman generation in LiNbO3 whispering-gallery mode disk resonators.

    Science.gov (United States)

    Simons, Matt T; Novikova, Irina

    2011-08-15

    In this Letter we report experimental demonstration of nonlinear frequency conversion at several optical frequencies in a whispering-gallery mode resonator (WGMR). Because of the enhancement of nonlinear interactions inside a WGMR, interaction of a 1064 nm pump field with a LiNbO(3) disk produced a weak but measurable non-phase-matched 532 nm second-harmonic field at room temperature (>100 °C below the phase-matching temperature) for pump powers of a few tens of milliwatts. For higher pump powers, we observed the generation of four additional fields at 545, 559, 573, and 587 nm. The relative spectral shift between two consecutive fields corresponds to a 455 cm(-1) vibrational mode in LiNbO(3) crystal. Our preliminary analysis indicates that these fields are the result of a multiphonon hyper-Raman scattering in which two photons of the pump field are converted into one photon of a higher-frequency field and one or several optical phonons.

  11. Implementation of single-photon quantum routing and decoupling using a nitrogen-vacancy center and a whispering-gallery-mode resonator-waveguide system.

    Science.gov (United States)

    Cao, Cong; Duan, Yu-Wen; Chen, Xi; Zhang, Ru; Wang, Tie-Jun; Wang, Chuan

    2017-07-24

    Quantum router is a key element needed for the construction of future complex quantum networks. However, quantum routing with photons, and its inverse, quantum decoupling, are difficult to implement as photons do not interact, or interact very weakly in nonlinear media. In this paper, we investigate the possibility of implementing photonic quantum routing based on effects in cavity quantum electrodynamics, and present a scheme for single-photon quantum routing controlled by the other photon using a hybrid system consisting of a single nitrogen-vacancy (NV) center coupled with a whispering-gallery-mode resonator-waveguide structure. Different from the cases in which classical information is used to control the path of quantum signals, both the control and signal photons are quantum in our implementation. Compared with the probabilistic quantum routing protocols based on linear optics, our scheme is deterministic and also scalable to multiple photons. We also present a scheme for single-photon quantum decoupling from an initial state with polarization and spatial-mode encoding, which can implement an inverse operation to the quantum routing. We discuss the feasibility of our schemes by considering current or near-future techniques, and show that both the schemes can operate effectively in the bad-cavity regime. We believe that the schemes could be key building blocks for future complex quantum networks and large-scale quantum information processing.

  12. Q-factor enhancement of integrated lithium-niobate-on-insulator ridge waveguide whispering-gallery-mode resonators by surface polishing

    Science.gov (United States)

    Wolf, Richard; Breunig, Ingo; Zappe, Hans; Buse, Karsten

    2017-02-01

    Whispering-gallery resonators (WGRs) are most promising for nonlinear-optical frequency-conversion due to their intensity enhancement by small mode volumes and high Q-factors. This has been shown frequently by millimeter-sized diamond-blade cut and polished bulk WGRs. For reproducible batch fabrication, however, the integration of WGRs into lithium-niobate-on-insulator (LNOI) substrates became of great interest. Here we report on integrated WGRs made by batch processes like lithography and reactive-ion etching. Since the Q-factor of integrated WGRs is limited by scattering losses, we focused on developing a polishing process for the waveguide sidewalls that allowed us to enhance the unloaded Q-factors already to more than 106 with room for further improvements. Furthermore we employ a coupling scheme with two waveguide chips, one comprising a linear coupling waveguide and one with the integrated WGR. By adjusting the distance between the coupling waveguide and the WGR, we can reproducibly and stably tune the coupling-efficiency between 0 and 95 %.

  13. Ex-house 2D finite-element simulation of the whispering-gallery modes of arbitrarily shaped axisymmetric electromagnetic resonators

    CERN Document Server

    Oxborrow, M

    2006-01-01

    It is described, explicitly, how a popular, commercially-available software package for solving partial-differential-equations (PDEs), as based on the finite-element method (FEM), can be configured to calculate the frequencies and fields of the whispering-gallery (WG) modes of axisymmetric dielectric resonators. The approach is traceable; it exploits the PDE-solver's ability to accept the definition of solutions to Maxwell's equations in so-called `weak form'. Associated expressions and methods for estimating a WG mode's volume, filling factor(s) and, in the case of closed(open) resonators, its wall (radiation) loss, are provided. As no transverse approxi-mation is imposed, the approach remains accurate even for so-called quasi-TM and -TE modes of low, finite azimuthal mode order. The approach's generality and utility are demonstrated by modeling several non-trivial structures: (i)two different optical microcavities [one toroidal made of silica, the other an AlGaAs microdisk]; (ii) a 3rd-order microwave Bragg...

  14. Second generation 50 K dual-mode sapphire oscillator.

    Science.gov (United States)

    Anstie, James D; Hartnett, John G; Tobar, Michael E; Ivanov, Eugene N; Stanwix, Paul L

    2006-02-01

    Low-temperature, high-precision sapphire resonators exhibit a turning point in mode frequency-temperature dependence at around 10 K. This, along with sapphire's extremely low dielectric losses at microwave frequencies, results in oscillator fractional frequency stabilities on the order of 10(-15). At higher temperatures the lack of a turning point makes single-mode oscillators very sensitive to temperature fluctuations. By exciting two quasi-orthogonal whispering gallery (WG) modes in a single sapphire resonator, a turning point in the frequency-temperature dependence can be found in the beat frequency between the two modes. A temperature control technique based on mode frequency temperature dependence has been used to maintain the sapphire at this turning point and the fractional frequency instability of the beat frequency has been measured to be at a level of 4.3 X 10(-14) over 1 s, dropping to 3.5 X 10(-14) over 4 s integration time.

  15. PEG Functionalization of Whispering Gallery Mode Optical Microresonator Biosensors to Minimize Non-Specific Adsorption during Targeted, Label-Free Sensing

    Directory of Open Access Journals (Sweden)

    Fanyongjing Wang

    2015-07-01

    Full Text Available Whispering Gallery Mode (WGM optical microresonator biosensors are a powerful tool for targeted detection of analytes at extremely low concentrations. However, in complex environments, non-specific adsorption can significantly reduce their signal to noise ratio, limiting their accuracy. To overcome this, poly(ethylene glycol (PEG can be employed in conjunction with appropriate recognition elements to create a nonfouling surface capable of detecting targeted analytes. This paper investigates a general route for the addition of nonfouling elements to WGM optical biosensors to reduce non-specific adsorption, while also retaining high sensitivity. We use the avidin-biotin analyte-recognition element system, in conjunction with PEG nonfouling elements, as a proof-of-concept, and explore the extent of non-specific adsorption of lysozyme and fibrinogen at multiple concentrations, as well as the ability to detect avidin in a concentration-dependent fashion. Ellipsometry, contact angle measurement, fluorescence microscopy, and optical resonator characterization methods were used to study non-specific adsorption, the quality of the functionalized surface, and the biosensor’s performance. Using a recognition element ratio to nonfouling element ratio of 1:1, we showed that non-specific adsorption could be significantly reduced over the controls, and that high sensitivity could be maintained. Due to the frequent use of biotin-avidin-biotin sandwich complexes in functionalizing sensor surfaces with biotin-labeled recognition elements, this chemistry could provide a common basis for creating a non-fouling surface capable of targeted detection. This should improve the ability of WGM optical biosensors to operate in complex environments, extending their application towards real-world detection.

  16. Thermal Control of a Dual Mode Parametric Sapphire Transducer

    CERN Document Server

    Belfi, Jacopo; De Michele, Andrea; Gabbriellini, Gianluca; Mango, Francesco; Passaquieti, Roberto

    2010-01-01

    We propose a method to control the thermal stability of a sapphire dielectric transducer made with two dielectric disks separated by a thin gap and resonating in the whispering gallery (WG) modes of the electromagnetic field. The simultaneous measurement of the frequencies of both a WGH mode and a WGE mode allows one to discriminate the frequency shifts due to gap variations from those due to temperature instability. A simple model, valid in quasi equilibrium conditions, describes the frequency shift of the two modes in terms of four tuning parameters. A procedure for the direct measurement of them is presented.

  17. Room Temperature Experiments with a Macroscopic Sapphire Mechanical Oscillator

    Science.gov (United States)

    Bourhill, Jeremy; Ivanov, Eugene; Tobar, Micahel

    2015-03-01

    We present initial results from a number of experiments conducted on a 0.53 kg sapphire ``dumbbell'' crystal. Mechanical motion of the crystal structure alters the dimensions of the crystal, and the induced strain changes the permittivity. These two effects frequency modulate resonant microwave whispering gallery modes, simultaneously excited within the crystal. A novel microwave readout system is described allowing extremely low noise measurements of this frequency modulation with a phase noise floor of -160 dBc/Hz at 100 kHz, near our modes of interest. Fine-tuning of the crystal's suspension have allowed for the optimisation of mechanical Q-factors in preparation for cryogenic experiments, with a value of 8 x 107 achieved so far. Finally, results are presented that demonstrate the excitation of mechanical modes via radiation pressure force. These are all important steps towards the overall goal of the experiment; to cool a macroscopic device to the quantum ground state.

  18. Polarization Dependent Whispering Gallery Modes in Microspheres

    Science.gov (United States)

    Adamovsky, Grigory (Inventor); Wrbanek, Susan Y. (Inventor)

    2016-01-01

    A tunable resonant system is provided and includes a microsphere that receives an incident portion of a light beam generated via a light source, the light beam having a fundamental mode, a waveguide medium that transmits the light beam from the light source to the microsphere, and a polarizer disposed in a path of the waveguide between the light source and the microsphere. The incident portion of the light beam creates a fundamental resonance inside the microsphere. A change in a normalized frequency of the wavelength creates a secondary mode in the waveguide and the secondary mode creates a secondary resonance inside the microsphere.

  19. Thermal Properties of Whispering Gallery Mode Resonators

    Science.gov (United States)

    2014-12-22

    Release; Distribution Unlimited 13. SUPPLEMENTARYNOTES The views, opinions and/or findings contained in this repmt are those of the author(s) and...platform because the toroidal microresonator is fabricated on chip and has a large suspended disk structure which is ideal for receiving IR radiation...the under-­‐cut silica disk to form a toroidal structure which has an extremely smooth surface that enhances optical quality. Oxygen plasma etching

  20. Test of Lorentz Invariance in Electrodynamics Using Rotating Cryogenic Sapphire Microwave Oscillators

    CERN Document Server

    Stanwix, P L; Wolf, P; Susli, M; Locke, C R; Ivanov, E N; Winterflood, J; Van Kann, F; Stanwix, Paul L.; Tobar, Michael E.; Wolf, Peter; Susli, Mohamad; Locke, Clayton R.; Ivanov, Eugene N.; Winterflood, John; Kann, Frank van

    2005-01-01

    We present the first results from a rotating Michelson-Morley experiment that uses two orthogonally orientated cryogenic sapphire resonator-oscillators operating in whispering gallery modes near 10 GHz. The experiment is used to test for violations of Lorentz Invariance in the frame-work of the photon sector of the Standard Model Extension (SME), as well as the isotropy term of the Robertson-Mansouri-Sexl (RMS) framework. In the SME we set a new bound on the previously unmeasured kappa_{e-}^{ZZ} component of 2.1(5.7)x10^{-14}, and set more stringent bounds by up to a factor of 7 on seven other components. In the RMS a more stringent bound of -2.6(2.1)x10^{-10} on the isotropy parameter, P_{MM}= delta - beta + 1/2 is set, which is a factor of 7 improvement.

  1. Gallery Information

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Paris-Beijing Photo Gallery Add: Dashanzi Art District, 4 Jiuxianqiao Rd, Chaoyang District. Beijing Exhibition Topic: Solo Photography Exhibition of Linus Ricard Date: May 5 to June 22 Tel: 86-10-84599263 Website: www.parisbeijingphotogallery. com

  2. Image Gallery

    Science.gov (United States)

    ... Accredited Practices EER Endowment for Education & Research Journal Image Gallery Click each image to enlarge. Fetal nose/lips Fetal nose, upper ... in the third trimester of pregnancy; the ultrasound image shows the chest of each fetus with the ...

  3. Tunable integrated optical filters based on sapphire microspheres and liquid crystals

    Science.gov (United States)

    Gilardi, Giovanni; Yilmaz, Hasan; Sharif Murib, Mohammed; Asquini, Rita; d'Alessandro, Antonio; Serpengüzel, Ali; Beccherelli, Romeo

    2010-05-01

    We present an integrated optical narrowband electrically tunable filter based on the whispering gallery modes of sapphire microspheres and double ion-exchanged channel BK7 glass waveguides. Tuning is provided by a liquid crystal infiltrated between the spheres and the glass substrate. By suitably choosing the radii of the spheres and of the circular apertures, upon which the spheres are positioned, arrays of different filters can be realized on the same substrate with a low cost industrial process. We evaluate the performance in terms of quality factor, mode spacing, and tuning range by comparing the numerical results obtained by the numerical finite element modeling approach and with the analytical approach of the Generalized Lorenz-Mie Theory for various design parameters. By reorienting the LC in an external electrical field, we demonstrate the tuning of the spectral response of the sapphire microsphere based filter. We find that the value of the mode spacing remains nearly unchanged for the different values of the applied electric field. An increase of the applied electric field strength, changes the refractive index of the liquid crystal, so that for a fixed geometry the mode spacing remains unchanged.

  4. DC-powered Fe3+:sapphire Maser and its Sensitivity to Ultraviolet Light

    CERN Document Server

    Oxborrow, Mark; Kersalé, Yann; Giordano, Vincent

    2010-01-01

    The zero-field Fe3+:sapphire whispering-gallery-mode maser oscillator exhibits several alluring features: Its output is many orders of magnitude brighter than that of an active hydrogen maser and thus far less degraded by spontaneous-emission (Schawlow-Townes) and/or receiving-amplifier noise. Its oscillator loop is confined to a piece of mono-crystalline rock bolted into a metal can. Its quiet amplification combined with high resonator Q provide the ingredients for exceptionally low phase noise. We here concentrate on novelties addressing the fundamental conundrums and technical challenges that impede progress. (1) Roasting: The "mase-ability" of sapphire depends significantly on the chemical conditions under which it is grown and heat-treated. We provide some fresh details and nuances here. (2) Simplification: This paper obviates the need for a Ka-band synthesizer: it describes how a 31.3 GHz loop oscillator, operating on the preferred WG pump mode, incorporating Pound locking, was built from low-cost compo...

  5. Precision measurement of a low-loss cylindrical dumbbell-shaped sapphire mechanical oscillator using radiation pressure

    Science.gov (United States)

    Bourhill, J.; Ivanov, E.; Tobar, M. E.

    2015-08-01

    We present first results from a number of experiments conducted on a 0.53-kg cylindrical dumbbell-shaped sapphire crystal. Here we report on an optomechanical experiment utilizing a modification to the typical cylindrical architecture. Mechanical motion of the crystal structure alters the dimensions of the crystal, and the induced strain changes the permittivity. These two effects result in parametric frequency modulation of resonant microwave whispering gallery modes that are simultaneously excited within the crystal. A microwave readout system is implemented, allowing extremely low noise measurements of this frequency modulation near our modes of interest, having a phase noise floor of -165 dBc/Hz at 100 kHz. Fine tuning of the crystal's suspension has allowed for the optimization of mechanical quality factors in preparation for cryogenic experiments, with a value of Q =8 ×107 achieved at 127 kHz. This results in a Q ×f product of 1013, equivalent to the best measured values in a macroscopic sapphire mechanical system. Results are presented that demonstrate the excitation of mechanical modes via radiation pressure force, allowing an experimental method of determining the transducer's displacement sensitivity d f /d x and calibrating the system. Finally, we demonstrate parametric backaction phenomenon within the system. These are all important steps towards the goal of achieving quantum limited measurements of a kilogram-scale macroscopic device for the purpose of detecting deviations from standard quantum theory resulting from quantum gravitational effects.

  6. Tone features in whispered Chinese

    Institute of Scientific and Technical Information of China (English)

    LI Xueli; XU Boling

    2005-01-01

    Study on the whispered tone is important to speech recognition and conversion in whispered Chinese. In this paper, the characteristics of whispered speech are introduced and the tone features in whispered Chinese are discussed. There is no fundamental frequency in the whispered speech, so other features, such as the amplitude envelope, duration, glottal area, lip area, forrnant, and vocal tract length, are extracted and their contributions to the automatic tone recognition are compared. From the experiments with six simple Chinese whispered vowels in four tones, it is proved that loudness-weighted 32 Mel-frequency bands log-amplitude envelopes and duration can be used as the main tone features in the whispered Chinese tone recognition. The average tone recognition rate approaches that of the human perception level.

  7. ART GALLERY IN LHASA

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Art galleries have emerged on the streets of Lhasa since the reform and opening up of China.The earliest ones were Art Gallery of Tibetan Exhibition Hall and Art Gallery of Potala Palace 20 years before.For 20 years as one fell,another rose until now,tens of art galleries of various sizes and centred around the Barkor Street are attracting enormous numbers of tourists from both home and abroad.

  8. Polarization Dependent Coupling of Whispering Gallery Modes in Microspheres

    Science.gov (United States)

    Adamovsky, G.; Wrbanek, S.; Floyd, B.; Crotty, M.

    2010-01-01

    Two sets of resonances in glass microspheres attached to a standard communication-grade single-mode optical fiber have been observed. It has been found that the strength of the resonances depends strongly on the polarization of the coupled light. Furthermore, the position of the resonances in the wavelength domain depends on the polarization of light in the optical fiber with maximum magnitudes shifted by approximately 45 .

  9. Whispering Gallery Mode Resonator Stabilized Narrow Linewidth Fiber Loop Laser

    CERN Document Server

    Sprenger, B; Wang, L J; 10.1364/OL.34.003370

    2012-01-01

    We demonstrate a narrow line, fiber loop laser using Erbium-doped fiber as the gain material, stabilized by using a microsphere as a transmissive frequency selective element. Stable lasing with a linewidth of 170 kHz is observed, limited by the experimental spectral resolution. A linear increase in output power and a red-shift of the lasing mode were also observed with increasing pump power. Its potential application is also discussed.

  10. Whispering Gallery Mode Resonator with Orthogonally Reconfigurable Filter Function

    Science.gov (United States)

    Maleki, Lute; Matsko, Andrey; Strekalov, Dmitry; Savchenkov, Anatoliy

    2008-01-01

    An optical resonator has been developed with reconfigurable filter function that has resonant lines that can be shifted precisely and independently from each other, creating any desirable combination of resonant lines. This is achieved by changing the axial distribution of the effective refractive index of the resonator, which shifts the resonant frequency of particular optical modes, leaving all the rest unchanged. A reconfigurable optical filter is part of the remote chemical detector proposed for the Mars mission (Planetary Instrument Definition and Development Program PIDDP), but it is also useful for photonic communications devices.

  11. Parity-Time-Symmetric Whispering-Gallery Microcavities

    Science.gov (United States)

    2014-04-06

    100084, China, 3Department of Physics, W ashingtonUniversity, St Louis, Missouri 63130, USA, 4 Dipartimento di Matematica e Fisica Ennio De Giorgi...photonic transition took place between two optical modes having different longitudinal wave vectors , and transverse modal profiles with different

  12. Ultimate resolution for refractometric sensing with whispering gallery mode microcavities.

    Science.gov (United States)

    Silverstone, J W; McFarlane, S; Manchee, C P K; Meldrum, A

    2012-04-09

    Many proposed microfluidic biosensor designs are based on the measurement of the resonances of an optical microcavity. Fluorescence-based resonators tend to be simpler and more robust than setups that use evanescent coupling from tuneable laser to probe the cavity. In all sensor designs the detection limits depend on the wavelength resolution of the detection system, which is a limitation of fluorescence-based devices. In this work, we explore the ultimate resolution and detection limits of refractometric microcavity sensor structures. Because many periodic modes are collected simultaneously from fluorescent resonators, standard Fourier methods can be best suited for rapid and precise analysis of the resonance shifts. Simple numerical expressions to calculate the ultimate sensor resolution and detection limits were found, and the results compared to experiments in which the resonances of fluorescent-core microcapillaries responded to various sucrose concentrations in water.

  13. Precision Measurement of a low-loss Cylindrical Dumbbell-Shaped Sapphire Mechanical Oscillator using Radiation Pressure

    CERN Document Server

    Bourhill, Jeremy; Tbar, Michael

    2015-01-01

    We present first results from a number of experiments conducted on a 0.53 kg cylindrical dumbbell-shaped sapphire crystal. This is the first reported optomechanical experiment of this nature utilising a novel modification to the typical cylindrical architecture. Mechanical motion of the crystal structure alters the dimensions of the crystal, and the induced strain changes the permittivity. These two effects result in parametric frequency modulation of resonant microwave whispering gallery modes that are simultaneously excited within the crystal. A novel low-noise microwave readout system is implemented allowing extremely low noise measurements of this frequency modulation near our modes of interest, having a phase noise floor of -165 dBc/Hz at 100 kHz. Fine-tuning of the crystal's suspension has allowed for the optimisation of mechanical quality factors in preparation for cryogenic experiments, with a value of Q=8 x 10^7 achieved at 127 kHz. This results in a Q x f product of 10^13, equivalent to the best mea...

  14. ARMA Modelling for Whispered Speech

    Institute of Scientific and Technical Information of China (English)

    Xue-li LI; Wei-dong ZHOU

    2010-01-01

    The Autoregressive Moving Average (ARMA) model for whispered speech is proposed. Compared with normal speech, whispered speech has no fundamental frequency because of the glottis being semi-opened and turbulent flow being created, and formant shifting exists in the lower frequency region due to the narrowing of the tract in the false vocal fold regions and weak acoustic coupling with the subglottal system. Analysis shows that the effect of the subglottal system is to introduce additional pole-zero pairs into the vocal tract transfer function. Theoretically, the method based on an ARMA process is superior to that based on an AR process in the spectral analysis of the whispered speech. Two methods, the least squared modified Yule-Walker likelihood estimate (LSMY) algorithm and the Frequency-Domain Steiglitz-Mcbride (FDSM) algorithm, are applied to the ARMA model for the whispered speech. The performance evaluation shows that the ARMA model is much more appropriate for representing the whispered speech than the AR model, and the FDSM algorithm provides a more accurate estimation of the whispered speech spectral envelope than the LSMY algorithm with higher computational complexity.

  15. Lunar Orbiter Photo Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Lunar Orbiter Photo Gallery is an extensive collection of over 2,600 high- and moderate-resolution photographs produced by all five of the Lunar Orbiter...

  16. NAIP Status Maps Gallery

    Data.gov (United States)

    Farm Service Agency, Department of Agriculture — NAIP Status Maps Gallery. These maps illustrate what aerial imagery collection is planned, whats been collected, when it is available and how it is available. These...

  17. Thermal Conductance through Sapphire-Sapphire Bonding

    Science.gov (United States)

    Suzuki, T.; Tomaru, T.; Haruyama, T.; Shintomi, T.; Uchinyama, T.; Miyoki, S.; Ohashi, M.; Kuroda, K.

    2003-07-01

    Thermal conductance on sapphire-sapphire bonded interface has been investigated. Two pieces of single crystal sapphire bar with square cross section were bonded together by adhesion free bonding. In two sections of the bar, thermal conductivity was measured between 5 K to 300K. One section contains a bonded interface and the other section measured a thermal conductivity of the sapphire as a reference. No significant thermal resistance due to bonded interface was found from this measurement. Obtained thermal conductivity reaches κ 1 × 104 [W/m·K] in temperature range of T = 20 ˜ 30 K which is a planned operating temperature of a cryogenic mirror of the Large scale Cryogenic Gravitational wave telescope. It looks promising for sapphire bonding technique to improve a heat transfer from a large cryogenic mirror to susp ension wires.

  18. The Hasler Gallery

    OpenAIRE

    2015-01-01

    Five artists and designers were given free rein of the Museum of Domestic Design and Architecture, as part of a local regeneration project in the Hasler Gallery, North Finchley. This was an exciting opportunity to develop new work inspired by the Museum's collections, and to show it in an unusual location. The site itself, the Hasler Gallery, was crucial to the success of the project and proved to be a catalyst for some of the work's development. As this book shows, all of the artists made c...

  19. An HI Rogues Gallery

    CERN Document Server

    Hibbard, J E; Rupen, M P; Schiminovich, D

    2001-01-01

    We have begun a compilation of HI maps of peculiar galaxies kindly contributed by individual investigators, many as part of the ``Gas & Galaxy Evolution'' conference. In this gallery we present images of the first 181 objects, which includes over 400 individually cataloged galaxies. The images consist of a greyscale representation of the optical morphology and an accompanying optical image with HI contours superimposed. A web-based ``living Gallery'' is being maintained on the NRAO homepage (presently at http://www.nrao.edu/astrores/HIrogues/).

  20. The Habitable Zone Gallery

    CERN Document Server

    Kane, Stephen R

    2012-01-01

    The Habitable Zone Gallery (www.hzgallery.org) is a new service to the exoplanet community which provides Habitable Zone (HZ) information for each of the exoplanetary systems with known planetary orbital parameters. The service includes a sortable table with information on the percentage of orbital phase spent within the HZ, planetary effective temperatures, and other basic planetary properties. In addition to the table, we also plot the period and eccentricity of the planets with respect to their time spent in the HZ. The service includes a gallery of known systems which plot the orbits and the location of the HZ with respect to those orbits. Also provided are animations which aid in orbit visualization and provide the changing effective temperature for those planets in eccentric orbits. Here we describe the science motivation, the under-lying calculations, and the structure of the web site.

  1. Covariance Data File Formats for Whisper-1.0 & Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-09

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation. It uses the sensitivity profile data for an application as computed by MCNP6 along with covariance files for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014. During 2015-2016, Whisper was updated to version 1.1 and is to be included with the upcoming release of MCNP6.2. This report describes the file formats used for the covariance data in both Whisper-1.0 and Whisper-1.1.

  2. User Manual for Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-26

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation [1-3]. It uses the sensitivity profile data for an application as computed by MCNP6 [4-6] along with covariance files [7,8] for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014 [3]. During 2015- 2016, Whisper was updated to version 1.1 and is to be included with the upcoming release of MCNP6.2. This document describes the user input and options for running whisper-1.1, including 2 perl utility scripts that simplify ordinary NCS work, whisper_mcnp.pl and whisper_usl.pl. For many detailed references on the theory, applications, nuclear data & covariances, SQA, verification-validation, adjointbased methods for sensitivity-uncertainty analysis, and more – see the Whisper – NCS Validation section of the MCNP Reference Collection at mcnp.lanl.gov. There are currently over 50 Whisper reference documents available.

  3. Release Notes for Whisper-1.1

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-27

    Whisper is a statistical analysis package developed in 2014 to support nuclear criticality safety (NCS) validation [1-3]. It uses the sensitivity profile data for an application as computed by MCNP6 [4-6] along with covariance files [7,8] for the nuclear data to determine a baseline upper-subcritical-limit (USL) for the application. Whisper version 1.0 was first developed and used at LANL in 2014 [3]. During 2015-2016, Whisper was updated to version 1.1 [9] and is to be included with the upcoming release of MCNP6.2. This document describes the Whisper-1.1 package that will be included with the MCNP6.2 release during 2017. Specific details are provided on the computer systems supported, the software quality assurance (SQA) procedures, installation, and testing. This document does not address other important topics, such as the importance of sensitivity-uncertainty (SU) methods to NCS validation, the theory underlying SU methodology, tutorials on the usage of MCNP-Whisper, practical approaches to using SU methodology to support and extend traditional validation, etc. There are over 50 documents included with Whisper-1.1 and available in the MCNP Reference Collection on the MCNP website (mcnp.lanl.gov) that address all of those topics and more. In this document, however, a complete bibliography of relevant MCNP-Whisper references is provided.

  4. Cool Cosmology: ``WHISPER" better than ``BANG"

    Science.gov (United States)

    Carr, Paul

    2007-10-01

    Cosmologist Fred Hoyle coined ``big bang'' as a term of derision for Belgian priest George Lemaitre's prediction that the universe had originated from the expansion of a ``primeval atom'' in space-time. Hoyle referred to Lamaitre's hypothesis sarcastically as ``this big bang idea'' during a program broadcast on March 28, 1949 on the BBC. Hoyle's continuous creation or steady state theory can not explain the microwave background radiation or cosmic whisper discovered by Penzias and Wilson in 1964. The expansion and subsequent cooling of Lemaitre's hot ``primeval atom'' explains the whisper. ``Big bang'' makes no physical sense, as there was no matter (or space) to carry the sound that Hoyle's term implies. The ``big bang'' is a conjecture. New discoveries may be able to predict the observed ``whispering cosmos'' as well as dark matter and the nature of dark energy. The ``whispering universe'' is cooler cosmology than the big bang. Reference: Carr, Paul H. 2006. ``From the 'Music of the Spheres' to the 'Whispering Cosmos.' '' Chapter 3 of Beauty in Science and Spirit. Beech River Books. Center Ossipee, NH, http://www.MirrorOfNature.org.

  5. How Long is the SLAC Gallery?

    Energy Technology Data Exchange (ETDEWEB)

    Imfeld, Hans; /SLAC

    2007-08-24

    How long is the gallery? Since the two methods of observation have similar accuracy and in the interest of keeping it simple, AEG averaged the two methods and determined that the length of the Gallery is 3073.72m.

  6. MoMLA: From Panel to Gallery

    Science.gov (United States)

    Vitanza, Victor, Ed.; Kuhn, Virginia, Ed.

    2013-01-01

    The work presented here in this "Panel to Gallery" was originally produced and assembled for the 2012 Modern Language Association Conference in Seattle, Washington. Similar to "From Gallery to Webtext", the event Victor curated for the 2006 College Composition and Communication Conference, this "Panel to Gallery" event at MLA set aside the…

  7. Remote Whispering Applying Time Reversal

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Brian Eric [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-07-16

    The purpose of this project was to explore the use of time reversal technologies as a means for communication to a targeted individual or location. The idea is to have the privacy of whispering in one’s ear, but to do this remotely from loudspeakers not located near the target. Applications of this work include communicating with hostages and survivors in rescue operations, communicating imaging and operational conditions in deep drilling operations, monitoring storage of spent nuclear fuel in storage casks without wires, or clandestine activities requiring signaling between specific points. This technology provides a solution in any application where wires and radio communications are not possible or not desired. It also may be configured to self calibrate on a regular basis to adjust for changing conditions. These communications allow two people to converse with one another in real time, converse in an inaudible frequency range or medium (i.e. using ultrasonic frequencies and/or sending vibrations through a structure), or send information for a system to interpret (even allowing remote control of a system using sound). The time reversal process allows one to focus energy to a specific location in space and to send a clean transmission of a selected signal only to that location. In order for the time reversal process to work, a calibration signal must be obtained. This signal may be obtained experimentally using an impulsive sound, a known chirp signal, or other known signals. It may also be determined from a numerical model of a known environment in which the focusing is desired or from passive listening over time to ambient noise.

  8. A fully integrated high-Q Whispering-Gallery Wedge Resonator

    CERN Document Server

    Ramiro-Manzano, F; Pavesi, L; Pucker, G; Ghulinyan, M

    2012-01-01

    Microresonator devices which posses ultra-high quality factors are essential for fundamental investigations and applications. Microsphere and microtoroid resonators support remarkably high Q's at optical frequencies, while planarity constrains preclude their integration into functional lightwave circuits. Conventional semiconductor processing can also be used to realize ultra-high-Q's with planar wedge-resonators. Still, their full integration with side-coupled dielectric waveguides remains an issue. Here we show the full monolithic integration of a wedge-resonator/waveguide vertically-coupled system on a silicon chip. In this approach the cavity and the waveguide lay in different planes. This permits to realize the shallow-angle wedge while the waveguide remains intact, allowing therefore to engineer a coupling of arbitrary strength between these two. The precise size-control and the robustness against post-processing operation due to its monolithic integration makes this system a prominent platform for indu...

  9. Adiabatic tapered optical fiber fabrication for exciting whispering gallery modes in microcavities

    Science.gov (United States)

    Chenari, Z.; Latifi, H.; Hashemi, R. S.; Doroudmand, F.

    2014-05-01

    This article demonstrates an investigation and analysis of a tapered fiber fabrication using an etchant droplet method. To achieve precise control on process, a two-step etching method is proposed (using 48% concentration of HF acid and Buffered HF) which results in low-loss adiabatic tapered fiber. A spectrum analysis monitoring in addition to a microscopy system was used to verify the etching progress. Tapers with losses less than 0.4 dB in air and 4.5 dB in water are demonstrated. A biconical fiber taper fabricated using this method was used to excite the WGMs on a microsphere surface in aquatic environment.

  10. Spatial refractive index sensor using whispering gallery modes in an optically trapped microsphere

    NARCIS (Netherlands)

    Zijlstra, P.; Zijlstra, Peter; van der Molen, K.L.; Mosk, Allard

    2007-01-01

    The authors propose the use of an optically trapped, dye doped polystyrene microsphere for spatial probing of the refractive index at any position in a fluid. Using the dye embedded in the microsphere as an internal broadband excitation source the authors eliminated the need for a tunable excitation

  11. Calculating Opto-Mechanically Induced Surface Acoustic Waves in a Silica Whispering Gallery Microresonator

    Science.gov (United States)

    2011-10-01

    8217{O .. •• ,..... N :I: t:. > u c: ~ ::s a OJ ’- u. l • ] Optica l State Number ver~us Frequency to Produce SAW: A2imutnal Optica l Modes...618 and 606 Interact to Generate SAW Mode 12 ~ ------.--:: Optica l Mode State Number Ml 618 - 2 606 United States Military Academy Photonics

  12. Spatial refractive index sensor using whispering gallery modes in an optically trapped microsphere

    NARCIS (Netherlands)

    Zijlstra, Peter; Molen, van der Karen L.; Mosk, Allard P.

    2007-01-01

    The authors propose the use of an optically trapped, dye doped polystyrene microsphere for spatial probing of the refractive index at any position in a fluid. Using the dye embedded in the microsphere as an internal broadband excitation source the authors eliminated the need for a tunable excitation

  13. Detection of Nanoparticles with a Frequency Locked Whispering Gallery Mode Microresonator

    CERN Document Server

    Swaim, Jon D; Bowen, Warwick P

    2013-01-01

    We detect 39 nm x 10 nm gold nanorods using a microtoroid stabilized via the Pound-Drever-Hall method. Real-time detection is achieved with signal-to-noise ratios up to 12.2. These nanoparticles are a factor of three smaller in volume than any other nanoparticle detected using WGM sensing to date. We show through repeated experiments that the measurements are reliable, and verify the presence of single nanorods on the microtoroid surface using electron microscopy. At our current noise level, the plasmonic enhancement of these nanorods could enable detection of proteins with radii as small as a = 2 nm.

  14. An Alternative Millimeter Wave Oscillator using a Dielectric Puck in the Whispering Gallery Mode Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A majority of millimeter wave based systems used for space exploration, communications and research, require a millimeter wave oscillator. These oscillators have...

  15. Whispering-gallery mode lasing from patterned molecular single-crystalline microcavity array

    NARCIS (Netherlands)

    Fang, Hong-Hua; Ding, Ran; Lu, Shi-Yang; Yang, Yue-De; Chen, Qi-Dai; Feng, Jing; Huang, Yong-Zhen; Sun, Hong-Bo; Fang, Honghua

    2013-01-01

    Organic single-crystalline materials have attracted great attention for laser applications. However, the fabrication of laser resonators and pattern of crystals are still intractable problems. Organic single crystals have been limited to fundamental property studies despite their superior photonic c

  16. What is- and what is not- Electromagnetically-Induced-Transparency in Whispering-Gallery-Microcavities

    CERN Document Server

    Peng, Bo; Chen, Weijian; Nori, Franco; Yang, Lan

    2014-01-01

    Electromagnetically-induced-transparency (EIT) and Autler-Townes splitting (ATS) are two prominent examples of coherent interactions between optical fields and multilevel atoms. They have been observed in various physical systems involving atoms, molecules, meta-structures and plasmons. In recent years, there has been an increasing interest in the implementations of all-optical analogues of EIT and ATS via the interacting resonant modes of one or more optical microcavities. Despite the differences in their underlying physics, both EIT and ATS are quantified by the appearance of a transparency window in the absorption or transmission spectrum, which often leads to a confusion about its origin. While in EIT the transparency window is a result of Fano interference among different transition pathways, in ATS it is the result of strong field-driven interactions leading to the splitting of energy levels. Being able to tell objectively whether a transparency window observed in the spectrum is due to EIT or ATS is cr...

  17. Harmonic mode locking in a high-Q whispering gallery mode microcavity

    Science.gov (United States)

    Tanabe, Takasumi; Kato, Takumi; Kobatake, Tomoya; Suzuki, Ryo; Chen-Jinnai, Akitoshi

    2016-03-01

    We present a numerical and experimental study of the generation of harmonic mode locking in a silica toroid microcavity. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We found that a stable harmonic mode-locking regime can be accessed when we reduce the input power after strong pumping even if we do not carefully adjust the wavelength detuning. This is due to the bistable nature of the nonlinear cavity system. The experiment agrees well with the numerical analysis, where we obtain a low-noise Kerr comb spectrum with a narrow longitudinal mode spacing by gradually reducing the input pump power after strong pumping. This finding clarifies the procedure for generating harmonic mode locking in such high-Q microcavity systems.

  18. Surface effects and gold-nanostructure surface coating of whispering-gallery microresonators

    Science.gov (United States)

    Ganta, Deepak

    Scope and method of study. The purpose of this study is to explore the surface effects of high-quality-factor optical microsphere resonators and thin-film-coated microresonators in various ambient gases. In this work, we present a systematic study of the assembly and characterization of gold nanostructures. We employ a wet-chemical synthesis method for growing gold nanorods and a directed electrochemical method for assembly of gold nanowires. The adhesion methods of gold nanostructures on high-quality-factor optical microsphere resonators are also investigated. Findings and conclusions. A novel method is employed for measuring thermal accommodation coefficients of various gases like nitrogen, helium and ambient air on several coated and uncoated surfaces of fused-silica microresonators, operating at room temperature. This method is further extended to measure the absorption coefficient of a surface film or water layer on a fused-silica microresonator, and provides a novel method to find the water layer desorption and adsorption rates on the surface of a microresonator in the presence of gases like ambient air and nitrogen. We have adapted methods for growing gold nanorods of different aspect ratios (AR), and developed a novel method of growing high-AR (20-400) gold nanowires from low-AR gold nanorods. Various methods were discovered to coat these gold nanostructures and carbon nanotubes on the fused-silica surface. The most successful method involves surface modification with MPMDMS (i.e., silanization) before coating with gold nanorods. These coating methods have made microresonators useful for plasmonic sensing applications.

  19. 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

    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....

  20. Optical Comb from a Whispering Gallery Mode Resonator for Spectroscopy and Astronomy Instruments Calibration

    Science.gov (United States)

    Strekalov, Dmitry V.; Yu, Nam; Thompson, Robert J.

    2012-01-01

    The most accurate astronomical data is available from space-based observations that are not impeded by the Earth's atmosphere. Such measurements may require spectral samples taken as long as decades apart, with the 1 cm/s velocity precision integrated over a broad wavelength range. This raises the requirements specifically for instruments used in astrophysics research missions -- their stringent wavelength resolution and accuracy must be maintained over years and possibly decades. Therefore, a stable and broadband optical calibration technique compatible with spaceflights becomes essential. The space-based spectroscopic instruments need to be calibrated in situ, which puts forth specific requirements to the calibration sources, mainly concerned with their mass, power consumption, and reliability. A high-precision, high-resolution reference wavelength comb source for astronomical and astrophysics spectroscopic observations has been developed that is deployable in space. The optical comb will be used for wavelength calibrations of spectrographs and will enable Doppler measurements to better than 10 cm/s precision, one hundred times better than the current state-of-the- art.

  1. Rayleigh scattering boosted multi-GHz displacement sensitivity in whispering gallery opto-mechanical resonators

    CERN Document Server

    Tallur, Siddharth

    2013-01-01

    Finite photon lifetimes for light fields in an opto-mechanical cavity impose a bandwidth limit on displacement sensing at mechanical resonance frequencies beyond the loaded cavity photon decay rate. Opto-mechanical modulation efficiency can be enhanced via multi-GHz transduction techniques such as piezo-opto-mechanics at the cost of on-chip integration. In this paper, we present a novel high bandwidth displacement sense scheme employing Rayleigh scattering in photonic resonators. Using this technique in conjunction with on-chip electrostatic drive in silicon enables efficient modulation at frequencies up to 9.1GHz. Being independent of the drive mechanism, this scheme could readily be extended to piezo-opto-mechanical and all optical transduced systems.

  2. World's largest sapphire for many applications

    Science.gov (United States)

    Khattak, Chandra P.; Shetty, Raj; Schwerdtfeger, C. Richard; Ullal, Saurabh

    2016-10-01

    Sapphire has been used for many high technology applications because of its excellent optical, mechanical, high temperature, abrasion resistance and dielectric properties. However, it is expensive and the volume of sapphire used has been limited. The potential sapphire requirements for LED and consumer electronic applications are very high. Emphasis has been on producing larger sapphire boules to achieve significant cost reductions so these applications are realized. World's largest sapphire boules, 500 mm diameter 300+kg, have been grown to address these markets.

  3. The Child Whisperer: Effective Parenting Strategies Adapted from "The Dog Whisperer"

    Science.gov (United States)

    McKinney, Cliff; Durr, Brandi

    2013-01-01

    Behavior modification with children has been popularized through television shows such as "Super Nanny" and "Nanny 911". The popularity of these shows may be related to the demand parents have for improving their children's behavior. Interestingly, an approach adopted by "The Dog Whisperer" may prove effective when used with children. The purpose…

  4. Whispers from the Edge of Physics

    Indian Academy of Sciences (India)

    Nils Andersson

    2017-09-01

    Neutron stars involve extreme physics which is difficult (perhaps impossible) to explore in laboratory experiments. We have to turn to astrophysical observations, and try to extract information from the entire range of the electromagnetic spectrum. In addition, neutron stars may radiate gravitational waves through a range of scenarios. This brief summary outlines some of the main ideas, focussing on what we do and do not know, and the challenges involved in trying to catch these faint whispers from the very edge of physics are described.

  5. Pumping of titanium sapphire laser

    Science.gov (United States)

    Jelínková, H.; Vaněk, P.; Valach, P.; Hamal, K.; Kubelka, J.; Škoda, V.; Jelínek, M.

    1993-02-01

    Two methods of Ti:Sapphire pumping for the generation of tunable laser radiation in the visible region were studied. For coherent pumping, the radiation of the second harmonic of a Nd:YAP laser was used and a maximum output energy of E out=4.5 mJ was reached from the Ti:Sapphire laser. For noncoherent pumping, two different lengths of flashlamp pulses were used and a maximum of E out=300 mJ was obtained. Preliminary estimations of the wavelength range of tunability were made.

  6. Neutron Transmission through Sapphire Crystals

    DEFF Research Database (Denmark)

    Sapphire crystals are excellent filters of fast neutrons, while at the same time exhibit moderate to very little absorption at smaller energies. We have performed an extensive series of measurements in order to quantify the above effect. Alongside our experiments, we have performed a series...... of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Those simulations were part of the effort of validating and improving the newly developed interface between the Monte-Carlo neutron transport code MCNP and the Monte Carlo ray-tracing code McStas....

  7. Early results from the Whisper instrument on Cluster: An overview

    DEFF Research Database (Denmark)

    Decreau, P.M.E.; Fergeau, P.; Krasnoselskikh, V.

    2001-01-01

    The Whisper instrument yields two data sets: (i) the electron density determined via the relaxation sounder, and (ii) the spectrum of natural plasma emissions in the frequency band 2-80 kHz. Both data sets allow for the three-dimensional exploration of the magnetosphere by the Cluster mission...... in normal telemetry mode and 0.3 s in burst mode telemetry, respectively. Recorded on board the four spacecraft, the Whisper density data set forms a reference for other techniques measuring the electron population. We give examples of Whisper density data used to derive the vector gradient, and estimate...

  8. Gallery of Portraits and Other Pictures

    Science.gov (United States)

    Velarde, M. G.

    Colleagues, scientific collaborators and visitors, and places… of significance in the life of Prof. M.G. Velarde. The gallery also illustrates the cosmopolitan life at Instituto Pluridisciplinar of Universidad Complutense of Madrid. Science is part of Culture.

  9. Segregation of Whispered Speech Interleaved with Noise or Speech Maskers

    Science.gov (United States)

    2011-08-01

    registers,” J. Acoust. Soc. Am. 96, 2101– 2107. [7] Scheffers, M.T.M., 1983. “Sifting vowels : auditory pitch analysis and sound segregation...signals provided by cochlear implants. Two studies investigated the segregation of simultaneously presented whispered vowels [7, 8] in a standard...double vowel identification paradigm. Both experiments found that pairs of concurrent whispered vowels were identified at the same rate as two vowels

  10. Gallery of Planetary Nebula Spectra

    CERN Document Server

    Kwitter, K B; Kwitter, Karen B.; Henry, Richard B.C.

    2006-01-01

    We present the Gallery of Planetary Nebula Spectra now available at http://oitwilliams.edu/nebulae. The website offers high-quality, moderate resolution (~7-10 A FWHM) spectra of 128 Galactic planetary nebulae from 3600-9600 A, obtained by Kwitter, Henry, and colleagues with the Goldcam spectrograph at the KPNO 2.1-m or with the RC spectrograph at the CTIO 1.5-m. The master PN table contains atlas data and an image link. A selected object's spectrum is displayed in a zoomable window; line identification templates are provided. In addition to the spectra themselves, the website also contains a brief discussion of PNe as astronomical objects and as contributors to our understanding of stellar evolution. We envision that this website, which concentrates a large amount of data in one place, will be of interest to a variety of users: researchers might need to check the spectrum of a particular object of interest; the non-specialist astronomer might simply be interested in perusing such a collection of spectra; and...

  11. Hydrogen effect on the properties of sapphire

    Science.gov (United States)

    Mogilevsky, Radion N.; Sharafutdinova, Liudmila G.; Nedilko, Sergiy; Gavrilov, Valeriy; Verbilo, Dmitriy; Mittl, Scott D.

    2009-05-01

    Sapphire is a widely used material for optical, electronic and semiconductor applications due to its excellent optical properties and very high durability. Optical and mechanical properties of sapphire depend on many factors such as the starting materials that are used to grow crystals, methods to grow sapphire crystals, etc. Demand for highest purity and quality of sapphire crystals increased ten fold for the last several years due to new applications for this material. In this work we studied the effect of starting materials and crystal growth methods on the optical and mechanical properties of sapphire, especially concentrating on the effect of hydrogen on the properties of sapphire. It was found that the infrared (IR) absorption which is traditionally used to measure the hydrogen content in sapphire crystals cannot be reliably used and the data obtained by this method provides a much lower hydrogen concentration than actual. We have shown for the first time that Nuclear Magnetic Resonance techniques can be successfully used to determine hydrogen concentration in sapphire crystals. We have shown that hydrogen concentration in sapphire can reach thousands of ppm if these crystals are grown from Verneuil starting material or aluminum oxide powder. Alternatively, the hydrogen concentration is very low if sapphire crystals are grown from High Purity Densified Alumina (HPDA®) as a starting material. HPDA® is produced by EMT, Inc through their proprietary patented technology. It was found that optical and mechanical properties of sapphire crystals grown using EMT HPDA® starting material are much better than those sapphire crystals grown using a starting material of Verneuil crystals or aluminum oxide powder.

  12. Lecture Notes on Criticality Safety Validation Using MCNP & Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Forrest B. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rising, Michael Evan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-03-11

    Training classes for nuclear criticality safety, MCNP documentation. The need for, and problems surrounding, validation of computer codes and data area considered first. Then some background for MCNP & Whisper is given--best practices for Monte Carlo criticality calculations, neutron spectra, S(α,β) thermal neutron scattering data, nuclear data sensitivities, covariance data, and correlation coefficients. Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the Monte Carlo radiation transport package MCNP. Whisper's methodology (benchmark selection – Ck's, weights; extreme value theory – bias, bias uncertainty; MOS for nuclear data uncertainty – GLLS) and usage are discussed.

  13. Rael Artel Gallery Tartus ja Varssavis

    Index Scriptorium Estoniae

    2006-01-01

    Rael Artel Gallery : Non-Profit Project Space'i tegevusest Tartus. 27.04-27.05. 2006 Varssavis Warszawski Aktyw Artystov'i ruumides näitus "Estonian Video Art. The blood project", osalesid Flo Kasearu, Gert Hatsukov, Külli K. Kaats, Allan Tõnissoo, Marko Nautras, Tanja Muravskaja ja Airi Triisberg

  14. Shooting Gallery Notes. Working Paper #22. Preliminary.

    Science.gov (United States)

    Bourgois, Philippe

    This paper contains ethnographic participant-observation field notes taken on a one-night visit to a "shooting gallery" in East Harlem (New York City) along with background information and commentary. East Harlem, also referred to as "El Barrio" or Spanish Harlem, is a 200-square block neighborhood on the upper East Side of Manhattan in New York…

  15. Rael Artel Gallery Tartus ja Varssavis

    Index Scriptorium Estoniae

    2006-01-01

    Rael Artel Gallery : Non-Profit Project Space'i tegevusest Tartus. 27.04-27.05. 2006 Varssavis Warszawski Aktyw Artystov'i ruumides näitus "Estonian Video Art. The blood project", osalesid Flo Kasearu, Gert Hatsukov, Külli K. Kaats, Allan Tõnissoo, Marko Nautras, Tanja Muravskaja ja Airi Triisberg

  16. A new frequency scale of Chinese whispered speech in the application of speaker identification

    Institute of Scientific and Technical Information of China (English)

    LIN Wei; YANG Lili; XU Boling

    2006-01-01

    In this paper, the frequency characteristics of Chinese whispered speech were investigated by a filter bank analysis. It was shown that the first and the third formants were more important than the other formants in the speaker identification of Chinese whispered speech. The experiment showed that the 800-1200 Hz and 2800-3200 Hz ranges were the most significant frequency ranges in discriminating the speaker. Based on this result, a new feature scale named whisper sensitive scale (WSS) was proposed to replace the common scale, Mel scale, and to extract the cepstral coefficient from whispered speech signal. Furthermore, a speaker identification system in whispered speech was presented based on the modified Hidden Markov Models integrating advantages of WSCC (the whisper sensitive cepstral coefficient) and LPCC. And the new system performed better in solving the problem of speaker identification of Chinese whispered speech than the traditional method.

  17. A Phenomenological Reading of Hegel's Concept of History of Philosophy:An Analysis of "The Gallery of Opinions","The Gallery of Knowledge" and "The Gallery of Dresden"

    Institute of Scientific and Technical Information of China (English)

    Ke Xiaogang

    2006-01-01

    From a phenomenological perspective of game-space and horizon,this paper tries to make a deconstructive reading of Hegel's "two galleries",namely,"the gallery of opinions"and "the gallery of knowledge",which are mentioned in the introduction of Hegel's Lectures on the History of Philosophy.The reading shows that the Game-space or the ab-gruendiger Grund of the Hegelian concept of philosophical history lies in an originally differencing space that is keeping in absence,which is called by Edmund Husserl and Jacques Derrida "the gallery of Dresden".

  18. Thermal bistability-based method for real-time optimization of ultralow-threshold whispering gallery mode microlasers

    CERN Document Server

    Lin, Guoping; Tillement, O; Cai, Zhiping; Lefèvre-Seguin, V; Hare, J

    2015-01-01

    A method based on thermal bistability for ultralow-threshold microlaser optimization is demonstrated. When sweeping the pump laser frequency across a pump resonance, the dynamic thermal bistability slows down the power variation. The resulting line shape modification enables a real-time monitoring of the laser characteristic. We demonstrate this method for a functionalized microsphere exhibiting a submicrowatt laser threshold. This approach is confirmed by comparing the results with a step-by-step recording in quasi-static thermal conditions.

  19. VUV 157nm laser ablation of spherical particles and modelling of whispering gallery mode optical antenna structures

    Energy Technology Data Exchange (ETDEWEB)

    Walton, C. D.; Cockcroft, S.; Metheringham, W. J. [Department of Physics, University of Hull, HU6 7RX (United Kingdom)

    2012-07-30

    We report on VUV 157nm F{sub 2} laser irradiation of CR-39 polymer substrates that have been intentionally seeded with spherical glass particles. We discuss the importance of adhesive forces for realizing spherical cavity structures by laser ablation. Strong optical absorption at 157nm in CR-39 enables precise control of pedestal height by controlling the laser fluence and the number of laser pulses. Resonant modes for free-standing spherical cavities have been calculated and we discuss briefly the potential applications for use as optical sources on-board lab-on-chip devices.

  20. Hysteresis behavior of Kerr frequency comb generation in a high-quality-factor whispering-gallery-mode microcavity

    Science.gov (United States)

    Kato, Takumi; Chen-Jinnai, Akitoshi; Nagano, Takuma; Kobatake, Tomoya; Suzuki, Ryo; Yoshiki, Wataru; Tanabe, Takasumi

    2016-07-01

    A numerical and experimental study of Kerr frequency comb generation in a silica toroid microcavity is presented. We use a generalized mean-field Lugiato-Lefever equation and solve it with the split-step Fourier method. We observe that a stable mode-locked regime can be accessed when we reduce the input power after strong pumping due to the bistable nature of the nonlinear cavity system used. The experimental results agree well with the results of the numerical analysis, where we obtain a low-noise Kerr comb spectrum by gradually reducing the pumping input after strong pumping. This finding complements the results obtained by a previous wavelength scanning method and clarifies the procedure for achieving mode-locked states in such high-Q microcavity systems.

  1. The interaction of lexical and phrasal prosody in whispered speech

    NARCIS (Netherlands)

    Heeren, W. F. L.; van Heuven, V. J.

    2014-01-01

    The production and perception of Dutch whispered boundary tones, i.e., phrasal prosody, was investigated as a function of characteristics of the tone-bearing word, i.e., lexical prosody. More specifically, the disyllabic tone-bearing word also carried a pitch accent, either on the same syllable as t

  2. Sapphire Viewports for a Venus Probe Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase 1 program will demonstrate that sapphire viewports are feasible for use in Venus probes. TvU's commercial viewport products have demonstrated that...

  3. Secondary particle emission from sapphire single crystal

    Energy Technology Data Exchange (ETDEWEB)

    Minnebaev, K.F., E-mail: minnebaev@mail.ru [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Khvostov, V.V.; Zykova, E.Yu.; Tolpin, K.A. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation); Colligon, J.S. [Manchester Metropolitan University, Chester Street, Manchester M1 5GD (United Kingdom); Yurasova, V.E. [Physics Faculty, Moscow State University, Leninskie Gory, Moscow 119991 (Russian Federation)

    2015-07-01

    Secondary ion emission from sapphire single crystal has been studied experimentally and by means of computer simulation. The particular oscillations of secondary ion energy spectra and two specific maxima of O{sup +} and Al{sup +} ions were observed under irradiation of (0001) sapphire face by 1 and 10 keV Ar{sup +} ions. We have explained this by the interplay of the charge exchange processes between moving particles and solids. The existence of two maxima in energy spectra of O{sup +} and Al{sup +} secondary ions can be also connected with special features of single-crystal sputtering: the low-energy peak can be formed by random sputtering and the high-energy peak from focusing collisions. In addition some similarity was found between the positions of low-energy maximum in energy spectra of Al{sup +} ions emitted from sapphire and the principal maxima of Al{sup +} ions ejected from the aluminum single crystal. This indicates a possibility to explain the presence of low-energy maximum in energy spectra of secondary ions ejecting from sapphire by emission of Al{sup +} ions from aluminum islands appearing in a number of cases on the sapphire surface due to preferential sputtering of oxygen. These different mechanisms of creating the energy spectra of ions emitted from sapphire should be taken in account.

  4. Wireless Hybrid Identification and Sensing Platform for Equipment Recovery (WHISPER) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Systems & Technologies proposed WHISPER (Wireless Hybrid Identification and Sensing Platform for Equipment Recovery) solution to NASA's need for...

  5. What's wrong with cinema in the gallery?

    OpenAIRE

    Hamlyn, Nicky

    2012-01-01

    This article builds on my earlier research (e.g. on William Raban's site-specific work) into the contemporary problem of showing moving image work in art galleries. The misfit between works' formal strategies and their mode of presentation is an ongoing issue. The essay is based on a review of two exhibitions held in London in 2011 of video works by Philippe Parreno, and Douglas Gordon. Parreno's show was praised as novel and exemplary for the way in which it marshalled its audience from...

  6. Whispered speaker identification based on feature and model hybrid compensation

    Institute of Scientific and Technical Information of China (English)

    GU Xiaojiang; ZHAO Heming; Lu Gang

    2012-01-01

    In order to increase short time whispered speaker recognition rate in variable chan- nel conditions, the hybrid compensation in model and feature domains was proposed. This method is based on joint factor analysis in training model stage. It extracts speaker factor and eliminates channel factor by estimating training speech speaker and channel spaces. Then in the test stage, the test speech channel factor is projected into feature space to engage in feature compensation, so it can remove channel information both in model and feature domains in order to improve recognition rate. The experiment result shows that the hybrid compensation can obtain the similar recognition rate in the three different training channel conditions and this method is more effective than joint factor analysis in the test of short whispered speech.

  7. Method of surface treatment on sapphire substrate

    Institute of Scientific and Technical Information of China (English)

    NIU Xin-huan; LIU Yu-ling; TAN Bai-mei; HAN Li-ying; ZHANG Jian-xin

    2006-01-01

    Sapphire single crystals are widely used in many areas because of the special physic properties and important application value. As an important substrate material,stringent surface quality requirements,i.e. surface finish and flatness,are required. The use of CMP technique can produce high quality surface finishes at low cost and with fast material removal rates. The sapphire substrate surface is treated by using CMP method. According to sapphire substrate and its product properties,SiO2 sol is chosen as abrasive. The particle size is 15-25 nm and the concentration is 40%. According to the experiment results,pH value is 10.5-11.5. After polishing and cleaning the sapphire surface,the surface roughness was measured by using AFM method and the lowest value of Ra 0.1 nm was obtained. From the results,it can be seen that using such method,the optimal sapphire surface can be gotten,which is advantageous for epitaxial growth and device making-up.

  8. Hearing smiles and frowns in normal and whisper registers.

    Science.gov (United States)

    Tartter, V C; Braun, D

    1994-10-01

    Two experiments measured listeners' abilities to detect facial expression in unfamiliar speech in normal and whisper registers. Acoustic differences between speech produced with neutral or marked facial expression were also assessed. Experiment 1 showed that in a forced-choice identification task, listeners could accurately select frowned speech as such, and neutral speech as happier sounding than frowned speech in the same speakers. Listeners were able to judge frowning in the same speakers' whispered speech. Relative to neutral speech, frowning lowers formant frequencies and increases syllable duration. In both registers, judgments of frowning and its relative happiness were significantly poorer for lip-rounded vowels, suggesting that listeners may recover lip protrusion in making judgments. Experiment 2 replicated the finding [V. Tartter, Percept. Psychophys. 27, 24-27 (1980)] that listeners can select speech produced with a smile as happier sounding than neutral speech in normal register, and extended the findings to whisper register. Relative to neutral, smiling increased second formant frequency. Results are discussed with respect to nonverbal auditory emotion prototypes and with respect to the direct realist theory of speech perception.

  9. Science Outreach through Art: A Journal Article Cover Gallery

    Science.gov (United States)

    McCullough, Ian

    2015-01-01

    Research faculty journal covers were used to create a gallery in the Science & Technology branch library at the University of Akron. The selection, presentation, and promotion process is shared along with copyright considerations and a review of galleries used for library outreach. The event and display was a great success attracting faculty…

  10. Coral Reefs: A Gallery Program, Grades 7-12.

    Science.gov (United States)

    National Aquarium in Baltimore, MD. Dept. of Education.

    Gallery classes at the National Aquarium in Baltimore give the opportunity to study specific aquarium exhibits which demonstrate entire natural habitats. The coral reef gallery class features the gigantic western Atlantic coral reef (325,000 gallons) with over 1,000 fish. The exhibit simulates a typical Caribbean coral reef and nearby sandy…

  11. Coral Reefs: A Gallery Program, Grades 7-12.

    Science.gov (United States)

    National Aquarium in Baltimore, MD. Dept. of Education.

    Gallery classes at the National Aquarium in Baltimore give the opportunity to study specific aquarium exhibits which demonstrate entire natural habitats. The coral reef gallery class features the gigantic western Atlantic coral reef (325,000 gallons) with over 1,000 fish. The exhibit simulates a typical Caribbean coral reef and nearby sandy…

  12. A Note on Edge Guards in Art Galleries

    CERN Document Server

    Nandakumar, R

    2011-01-01

    We examine the Art Gallery Problem with Edge Guards. We present a heuristic algorithm to arrange edge guards to guard only the inward side of the walls of any N-vertex simple polygonal gallery using at most roof (N/4) edge guards - a weakened version of Toussaint's conjecture on the number of edge guards that can guard an entire simple polygon

  13. Sapphire Energy - Integrated Algal Biorefinery

    Energy Technology Data Exchange (ETDEWEB)

    White, Rebecca L. [Sapphire Energy, Inc., Columbus, NM (United States). Columbus Algal Biomass Farm; Tyler, Mike [Sapphire Energy, Inc., San Diego, CA (United States)

    2015-07-22

    Sapphire Energy, Inc. (SEI) is a leader in large-scale photosynthetic algal biomass production, with a strongly cohesive research, development, and operations program. SEI takes a multidiscipline approach to integrate lab-based strain selection, cultivation and harvest and production scale, and extraction for the production of Green Crude oil, a drop in replacement for traditional crude oil.. SEI’s technical accomplishments since 2007 have produced a multifunctional platform that can address needs for fuel, feed, and other higher value products. Figure 1 outlines SEI’s commercialization process, including Green Crude production and refinement to drop in fuel replacements. The large scale algal biomass production facility, the SEI Integrated Algal Biorefinery (IABR), was built in Luna County near Columbus, New Mexico (see fig 2). The extraction unit was located at the existing SEI facility in Las Cruces, New Mexico, approximately 95 miles from the IABR. The IABR facility was constructed on time and on budget, and the extraction unit expansion to accommodate the biomass output from the IABR was completed in October 2012. The IABR facility uses open pond cultivation with a proprietary harvesting method to produce algal biomass; this biomass is then shipped to the extraction facility for conversion to Green Crude. The operation of the IABR and the extraction facilities has demonstrated the critical integration of traditional agricultural techniques with algae cultivation knowledge for algal biomass production, and the successful conversion of the biomass to Green Crude. All primary unit operations are de-risked, and at a scale suitable for process demonstration. The results are stable, reliable, and long-term cultivation of strains for year round algal biomass production. From June 2012 to November 2014, the IABR and extraction facilities produced 524 metric tons (MT) of biomass (on a dry weight basis), and 2,587 gallons of Green Crude. Additionally, the IABR

  14. Bonding of sapphire to sapphire by eutectic mixture of aluminum oxide and zirconium oxide

    Science.gov (United States)

    Deluca, J. J. (Inventor)

    1979-01-01

    An element comprising sapphire, ruby or blue sapphire can be bonded to another element of such material with a eutectic mixture of aluminum oxide and zirconium oxide. The bonding mixture may be applied in the form of a distilled water slurry or by electron beam vapor deposition. In one embodiment the eutectic is formed in situ by applying a layer of zirconium oxide and then heating the assembly to a temperature above the eutectic temperature and below the melting point of the material from which the elements are formed. The formation of a sapphire rubidium maser cell utilizing eutectic bonding is shown.

  15. A comparative study on methods to structure sapphire

    NARCIS (Netherlands)

    Crunteanu, A.; Hoffmann, P.; Pollnau, M.; Buchal, C.

    2003-01-01

    Ti:sapphire is an attractive material for applications as a tunable or short-pulse laser and as a broadband light source in low-coherence interferometry. We investigated several methods to fabricate rib structures in sapphire that can induce channel waveguiding in Ti:sapphire planar waveguides. Thes

  16. Promenade Among Words and Things: The Gallery as Catalogue, the Catalogue as Gallery

    Directory of Open Access Journals (Sweden)

    Mari Lending

    2015-12-01

    Full Text Available In the mid nineteenth century new casting techniques allowed for the production of huge architectural fragments. Well-selected collections could ideally display perfect series in galleries in which the visitor could wander among monuments and experience architecture history on full scale. The disembodied material of plaster was considered capable of embodying a number of modern historical taxonomies and aesthetical programs, most importantly chronology, comparison, style, and evolution. Veritable showcases of historicism, the casts could illustrate in spatial arrangements new conceptions on the history, contemporaneity and future of architecture. Plaster cast became a main medium in which to publish antiquities as novelties for grand audiences, taking the printed and published beyond the two-dimensional space of words and images. However, due to the increasing market of casts and their sheere size and weight, the reproductions as mounted in the galleries often behaved as unruly as architecture does outside curatorial control. In the end only the catalogues, the paper versions of these imaginary museums were capable to create the orders that their plaster referents constantly aspired to destroy. An important chapter in the history of the architecture museum these plaster monuments belong to a part of architectural print culture in which catalogues were curated and galleries edited. Metaphors drawn from the realm of writing saturated the discourse on the display of casts. Images and texts fluctuated and the image-objects were compared to books, paper, pages, documents and libraries but above all to illustrations inviting promenades in time and space.

  17. Sapphire and other dielectric waveguide devices

    NARCIS (Netherlands)

    Pollnau, Markus

    2008-01-01

    Different fabrication methods have been explored successfully and surface and buried channel waveguide lasers have been demonstrated in Ti:sapphire for the first time. Since the propagation losses of these first-generation waveguides are still rather high, substantial improvement is required in orde

  18. Sapphire and other dielectric waveguide devices

    NARCIS (Netherlands)

    Pollnau, Markus

    Different fabrication methods have been explored successfully and surface and buried channel waveguide lasers have been demonstrated in Ti:sapphire for the first time. Since the propagation losses of these first-generation waveguides are still rather high, substantial improvement is required in

  19. Advanced thin dicing blade for sapphire substrate

    Directory of Open Access Journals (Sweden)

    Koji Matsumaru, Atsushi Takata and Kozo Ishizaki

    2005-01-01

    Full Text Available Advanced thin dicing blades for cutting sapphire were fabricated and evaluated for cutting performance with respect to dicing blade wear and meandering of cutting lines. Three kinds of different commercial blades were used to compare the cutting performance. These blades had the same thickness and the same diamond grain size. The matrix material of one dicing blade was nickel–phosphorus alloy and two other were a vitric material. Newly developed dicing blades consisted of a vitric material with pore. A dicing machine was used for cutting sapphire. Turning velocity, cutting depth and feeding rate were 20,000 min−1, 200 μm and 1 mm s−1, respectivity. Cutting directions were 110 and 010. All blades could cut 1000 mm and more in the 110 direction. On the other hand, commercial dicing blades generated meandering lines and were broken only by 50 mm of cutting length in 010 direction. Fabricated blade can cut 1000 mm and more in 010 direction. The wear of fabricated dicing blade was the largest in the dicing blades. Although cutting performance of commercial dicing blades depended on the sapphire orientation, that of fabricated blade was independent of the sapphire orientation. It has been confirmed that the fabricated dicing blade was kept a cutting ability by flash diamonds on the dicing blade surface, which were created by wear of blade during cutting sapphire. Low cutting ability of commercial blades increased cutting force between with increase of cutting length. The increased cutting force produced to bend a blade and cutting lines, and finally a fracture of blade.

  20. Moths are not silent, but whisper ultrasonic courtship songs

    DEFF Research Database (Denmark)

    Nakano, R; Takanashi, T; Fujii, T

    2009-01-01

    Ultrasonic hearing is widespread among moths, but very few moth species have been reported to produce ultrasounds for sexual communication. In those that do, the signals are intense and thus well matched for long distance communication. By contrast, males of the Asian corn borer moth (Crambidae......) were recently shown to whisper extremely low-intensity ultrasonic courtship songs close to females. Since low sound levels will prevent eavesdropping by predators, parasites and conspecific rivals, we predicted low intensity ultrasound communication to be widespread among moths. Here we tested 13...

  1. Advertising identities: virtual galleries as places of identity

    Directory of Open Access Journals (Sweden)

    Alexandra Zontea

    2010-10-01

    Full Text Available This paper is focused on the public presentation of self through virtual art galleries, singling out the field of photography. Photography has always been disputed as being part of the highbrow arts because of its popular character. Today, anyone who owes a photo camera can experience photography as art, without a rigorous training. Everybody is able to expose the photos freely to a large number of people, on the Internet. Consequently, the Internet opens up a virtual space, in which photo artists and amateurs can promote their works and exhibit them in a personal online gallery, which represents their place in the virtual vastness. Therefore, my research approaches the matter of the virtual gallery as an identitary place, being focused on finding out why artists choose to exhibit in virtual galleries. I asked myself what are the new functions of the virtual art galleries?Are they understood as online markers that distinguish the owners in these virtual environments? In other words, are these personal galleries a way of expressing online identities?

  2. Surface modification of sapphire by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    McHargue, C.J.

    1998-11-01

    The range of microstructures and properties of sapphire (single crystalline Al{sub 2}O{sub 3}) that are produced by ion implantation are discussed with respect to the implantation parameters of ion species, fluence, irradiation temperature and the orientation of the ion beam relative to crystallographic axes. The microstructure of implanted sapphire may be crystalline with varying concentrations of defects or it may be amorphous perhaps with short-range order. At moderate to high fluences, implanted metallic ions often coalesce into pure metallic colloids and gas ions form bubbles. Many of the implanted microstructural features have been identified from studies using transmission electron microscopy (TEM), optical spectroscopy, Moessbauer spectroscopy, and Rutherford backscattering-channeling. The chemical, mechanical, and physical properties reflect the microstructures.

  3. The growth of sapphire single crystals

    Directory of Open Access Journals (Sweden)

    STEVAN DJURIC

    2001-06-01

    Full Text Available Sapphire (Al2O3 single crystals were grown by the Czochralski technique both in air and argon atmospheres. The conditions for growing sapphire single crystals were calculated by using a combination of Reynolds and Grashof numbers. Acritical crystal diameter dc = 20 mm and the critical rate of rotation wc = 20 rpm were calculated from the hydrodynamics of the melt. The value of the rate of crystal growth was experimentally found to be 3.5 mm/h. According to our previous experiments, it was confirmed that three hours exposures to conc. H3PO4 at 593 K was suitable for chemical polishing. Also, three hours exposure to conc.H3PO4 at 523 K was found to be a suitable etching solution. The lattice parameters a = 0.47573 nm and c = 1.29893 nm were determined by X-ray powder diffraction. The obtained results are discussed and compared with published data.

  4. CFD analysis of heat collection in a glazed gallery

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, Maria Jose; Gutierrez, Antonio Jose; Pistono, Jorge; Blanco, Eduardo [Universidad de Oviedo, EDZE (Energia), Campus de Viesques, 33271 Gijon, Asturias (Spain)

    2011-01-15

    A glazed gallery in most old buildings is a space located on the first floor (and/or higher floors), facing south and almost fully glazed. As a result of the large glazed area and the orientation of the gallery, its temperature is warmer than the exterior and, in cold weather, it is used both as a space to insulate the adjacent rooms and as a leisure area, among other applications. In the framework of the ARFRISOL project (Bioclimatic Architecture and Solar Cooling), a demonstration container has been constructed in northern Spain (Asturias) which includes, among other bioclimatic elements, a glazed gallery. This gallery is considered as an element of Bioclimatic Architecture that enables solar radiation to be collected and the energy obtained to be used to support the building's air conditioning system. It consists of a south-facing glazed exterior wall, an intermediate space or passage and a partially glazed interior wall. Dampers located in the floor and ceiling of the intermediate space and connected to the air ducts enable the air circulating inside the gallery to be heated or cooled, depending on the season of the year, before it is further conditioned and conveyed to the rooms. This paper focuses on the three-dimensional numerical simulation of the airflow inside the gallery. The aim is to obtain a model to evaluate the thermal energy obtained in this architectural feature, integrating the effect of certain variables, such as the incident solar irradiation, the outdoor temperature and the air flow rate circulating in the gallery. (author)

  5. Photonic detection and characterization of DNA using sapphire microspheres

    OpenAIRE

    Serpengüzel, Ali; Murib, Mohammed Sharif; Yeap, Weng-Siang; Martens, Daan; Bienstman, Peter; De Ceuninck, Ward; van Grinsven, Bart; Schoening, Michael J.; Michiels, Luc; Haenen, Ken; Ameloot, Marcel; Wagner, Patrick

    2014-01-01

    A microcavity-based deoxyribonucleic acid (DNA) optical biosensor is demonstrated for the first time using synthetic sapphire for the optical cavity. Transmitted and elastic scattering intensity at 1510 nm are analyzed from a sapphire microsphere (radius 500 mu m, refractive index 1.77) on an optical fiber half coupler. The 0.43 nm angular mode spacing of the resonances correlates well with the optical size of the sapphire sphere. Probe DNA consisting of a 36-mer fragment was covalently immob...

  6. Sapphire Multiple Filament and Large Plate Growth Processes

    Science.gov (United States)

    1972-10-01

    for sapphire filaments is scrap white verneuil -grown sapphire boules. These boules are processed here at Tyco to achieve the proper mesh size...entrapped liquid freeze, they shrink, resulting in voids. Raw material for our growth process is provided by use of scap verneuil sapphire boules. In...J ;~ ;t" ,, ,, .. ::~ ,:~~\\i : i .<’\\ :1 ’ r .,l,, .. ’ ... :,J_ ’ ’~~ .. ;~ 1-.. i d;·, AFML-TR -7---190 1;).-- SAPPHIRE MULTIPLE

  7. REINFORCEMENT OF NICKEL CHROMIUM ALLOYS WITH SAPPHIRE WHISKERS.

    Science.gov (United States)

    SAPPHIRE, COMPOSITE MATERIALS, CERAMIC FIBERS , CERAMIC FIBERS , TITANIUM COMPOUNDS, ZIRCONIUM COMPOUNDS, HYDRIDES, ADDITIVES, CHROMIUM ALLOYS, FIBER METALLURGY, IRON COMPOUNDS, ENCAPSULATION, DENSITY, SURFACE TENSION.

  8. Commissioning and Performance Analysis of WhisperGen Stirling Engine

    Science.gov (United States)

    Pradip, Prashant Kaliram

    Stirling engine based cogeneration systems have potential to reduce energy consumption and greenhouse gas emission, due to their high cogeneration efficiency and emission control due to steady external combustion. To date, most studies on this unit have focused on performance based on both experimentation and computer models, and lack experimental data for diversified operating ranges. This thesis starts with the commissioning of a WhisperGen Stirling engine with components and instrumentation to evaluate power and thermal performance of the system. Next, a parametric study on primary engine variables, including air, diesel, and coolant flowrate and temperature were carried out to further understand their effect on engine power and efficiency. Then, this trend was validated with the thermodynamic model developed for the energy analysis of a Stirling cycle. Finally, the energy balance of the Stirling engine was compared without and with heat recovery from the engine block and the combustion chamber exhaust.

  9. Structure of the Dislocation in Sapphire

    DEFF Research Database (Denmark)

    Bilde-Sørensen, Jørgen; Thölen, A. R.; Gooch, D. J.;

    1976-01-01

    of ⅓ 01 0 and are separated by two identical faults. The distance between two partials is in the range 75-135 Å, corresponding to a fault energy of 320±60 mJ/m2. Perfect 01 0 dislocations have also been observed. These dislocations exhibited either one or two peaks when imaged in the (03 0) reflection......Experimental evidence of the existence of 01 0 dislocations in the {2 0} prism planes in sapphire has been obtained by transmission electron microscopy. By the weak-beam technique it has been shown that the 01 0 dislocations may dissociate into three partials. The partials all have a Burgers vector...

  10. Indoor/outdoor ozone concentrations at a contemporary art gallery

    Energy Technology Data Exchange (ETDEWEB)

    Davies, T.D.; Ramer, B.; Kaspyzok, G.; Delany, A.C.

    1984-02-01

    Ozone concentrations were measured both inside and outside the Sainsbury Centre for Visual Arts, near a small city in rural eastern England, during a three-week period in summer. The inside concentration was typically 70 +/- 10% of the outside concentration during the period of expected maximum outside levels. During the period of observation the maximum outside ozone levels have been well in excess of 120 ppb. The relatively high indoor/outdoor ozone ratio is a function of the Centre's design, its internal geometry, and its ventilation system. Conventional art galleries and museums experience much lower indoor ozone exposure. The measured indoor ozone levels imply deleterious effects on the gallery exhibits and an enhanced ozone exposure may have to be considered in the design of modern galleries and museums. 8 references.

  11. Portion of Enhanced 360-degree Gallery Pan

    Science.gov (United States)

    1997-01-01

    This is a sub-section of the 'geometrically improved, color enhanced' version of the 360-degree panorama heretofore known as the 'Gallery Pan', the first contiguous, uniform panorama taken by the Imager for Mars Pathfinder (IMP) over the course of Sols 8, 9, and 10. Different regions were imaged at different times over the three Martian days to acquire consistent lighting and shadow conditions for all areas of the panorama.The IMP is a stereo imaging system that, in its fully deployed configuration, stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters. In this geometrically improved version of the panorama, distortion due to a 2.5 degree tilt in the IMP camera mast has been removed, effectively flattening the horizon.The IMP has color capability provided by 24 selectable filters -- twelve filters per 'eye'. Its red, green, and blue filters were used to take this image. The color was digitally balanced according to the color transmittance capability of a high-resolution TV at the Jet Propulsion Laboratory (JPL), and is dependent on that device. In this color enhanced version of the panorama, detail in surface features are brought out via changes to saturation and intensity, holding the original hue constant. A threshold was applied to avoid changes to the sky.At left is a Lander petal and a metallic mast which is a portion of the low-gain antenna. Misregistration in the antenna and other Lander features is due to parallax in the extreme foreground. Another Lander petal is at the right, showing the fully deployed forward ramp.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech). The IMP was developed by the University of Arizona Lunar

  12. Double Sided Si(Ge)/Sapphire/III-Nitride Hybrid Structure

    Science.gov (United States)

    Park, Yeonjoon (Inventor); Choi, Sang Hyouk (Inventor)

    2016-01-01

    One aspect of the present invention is a double sided hybrid crystal structure including a trigonal Sapphire wafer containing a (0001) C-plane and having front and rear sides. The Sapphire wafer is substantially transparent to light in the visible and infrared spectra, and also provides insulation with respect to electromagnetic radio frequency noise. A layer of crystalline Si material having a cubic diamond structure aligned with the cubic direction on the (0001) C-plane and strained as rhombohedron to thereby enable continuous integration of a selected (SiGe) device onto the rear side of the Sapphire wafer. The double sided hybrid crystal structure further includes an integrated III-Nitride crystalline layer on the front side of the Sapphire wafer that enables continuous integration of a selected III-Nitride device on the front side of the Sapphire wafer.

  13. From GUI to Gallery: A Study of Online Virtual Environments.

    Science.gov (United States)

    Guynup, Stephen Lawrence

    This paper began as an attempt to clarify and classify the development of Web3D environments from 1995 to the present. In that process, important facts came to light. A large proportion of these sites were virtual galleries and museums. Second, these same environments covered a wide array of architectural interpretations and represented some of…

  14. Experimental Study on Optimal Layout of Grid Desilting Gallery

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yaozhe; WANG Jingchang; CHANG Zhichao; ZHANG Yi

    2009-01-01

    Based on the desilting research of one scheduling project in the southwest of China, the method of setting grid desilting gallcry before the desilting tunnel is put forward to expand the scope of the scouring funnel before the dam and solve the problem of sediment deposition at the power station water intake. The experimental results show that, in the design of a grid desilting gallery, the width of the grid gallery should not be smaller than that of the desilting bottom in-take, the size of the grid orifice should be in the range of 1.5 m-2.0 m along the flow direction, and the grid spacing should be 3-5 times the size of the grid orifice. The discharging ability of the desilting bottom intake will decrease after the grid desilting gallery is added. The average of the decrease rates is about 5%-10%. The scouring funnel draws in the longitudinal direction before the dam obviously after the construction of the grid desilting gallery.

  15. Rain Erosion Behavior of Silicon Dioxide Films Prepared on Sapphire

    Institute of Scientific and Technical Information of China (English)

    Liping FENG; Zhengtang LIU; Wenting LIU

    2005-01-01

    Silicon dioxide (SiO2) films were prepared on sapphire (α-Al2O3) by radio frequency magnetron reactive sputtering in order to in crease both transmission and rain erosion resistant performance of infrared domes of sapphire. Composition and structure of SiO2 films were analyzed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD),respectively. The transmittance of uncoated and coated sapphire was measured using a Fourier transform infrared(FTIR) spectrometer. Rain erosion tests of the uncoated and coated sapphire were performed at 211 m/s impact velocity with an exposure time ranging from 1 to 8 min on a whirling arm rig. Results show that the deposited films can greatly increase the transmission of sapphire in mid-wave IR. After rain erosion test, decreases in normalized transmission were less than 1% for designed SiO2 films and the SiO2 coating was strongly bonded to the sapphire substrate. In addition, sapphires coated with SiO2 films had a higher transmittance than uncoated ones after rain erosion.

  16. Effect of Propellant Combustion on Sapphire

    Directory of Open Access Journals (Sweden)

    Mark L. Bundy

    2000-10-01

    Full Text Available Sapphire (Al2O3 is the window material of choice for laser beam transmission into the combustion chamber of laser-ignited guns. To evaluate the long-term effects of propellant combustion on an Al/sub 2/O/sub 3/ laser window, it is important to know the window temperature during firing. This paper presents temperature data on an Al/sub 2/O/sub 3/ sample located in the breech face of the gun where the laser window would be in a laser-ignited 155 mm(M199 cannon. Al/sub 2/O/sub 3/ sample is a substrate material of a commercially sold thin-film thermocouple, and is therefore thermally, if not optically, representative of an actual Al/sub 2/O/sub 3/ laser window.

  17. Ruby and sapphire from Jegdalek, Afghanistan

    Science.gov (United States)

    Bowersox, G.W.; Foord, E.E.; Laurs, B.M.; Shigley, J.E.; Smith, C.P.

    2000-01-01

    This study provides detailed mining and gemological information on the Jegdalek deposit, in east-central Afghanistan, which is hosted by elongate beds of corundum-bearing marble. Some facet-grade ruby has been recovered, but most of the material consists of semitransparent pink sapphire of cabochon or carving quality. The most common internal features are dense concentrations of healed and nonhealed fracture planes and lamellar twin planes. Color zoning is common, and calcite, apatite, zircon, mica, iron sulfide minerals, graphite, rutile, aluminum hydroxide, and other minerals are also present in some samples. Although the reserves appear to be large, future potential will depend on the establishment of a stable government and the introduction of modern mining and exploration techniques. ?? 2000 Gemological Institute of America.

  18. Synthesis of titanium sapphire by ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Morpeth, L.D.; McCallum, J.C.; Nugent, K.W. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1998-06-01

    Since laser action was first demonstrated in titanium sapphire (Ti:Al{sub 2}O{sub 3}) in 1982, it has become the most widely used tunable solid state laser source. The development of a titanium sapphire laser in a waveguide geometry would yield an elegant, compact, versatile and highly tunable light source useful for applications in many areas including optical telecommunications. We are investigating whether ion implantation techniques can be utilised to produce suitable crystal quality and waveguide geometry for fabrication of a Ti:Al{sub 2}O{sub 3} waveguide laser. The implantation of Ti and O ions into c-axis oriented {alpha}-Al{sub 2}O{sub 3} followed by subsequent thermal annealing under various conditions has been investigated as a means of forming the waveguide and optimising the fraction of Ti ions that have the correct oxidation state required for laser operation. A Raman Microprobe is being used to investigate the photo-luminescence associated with Ti{sup 3+} ion. Initial photoluminescence measurements of ion implanted samples are encouraging and reveal a broad luminescence profile over a range of {approx} .6 to .9 {mu}m, similar to that expected from Ti{sup 3+}. Rutherford Backscattering and Ion Channelling analysis have been used to study the crystal structure of the samples following implantation and annealing. This enables optimisation of the implantation parameters and annealing conditions to minimise defect levels which would otherwise limit the ability of light to propagate in the Ti:Al{sub 2O}3 waveguide. (authors). 8 refs., 3 figs.

  19. Polishing Sapphire Substrates by 355 nm Ultraviolet Laser

    Directory of Open Access Journals (Sweden)

    X. Wei

    2012-01-01

    Full Text Available This paper tries to investigate a novel polishing technology with high efficiency and nice surface quality for sapphire crystal that has high hardness, wear resistance, and chemical stability. A Q-switched 355 nm ultraviolet laser with nanosecond pulses was set up and used to polish sapphire substrate in different conditions in this paper. Surface roughness Ra of polished sapphire was measured with surface profiler, and the surface topography was observed with scanning electronic microscope. The effects of processing parameters as laser energy, pulse repetition rate, scanning speed, incident angle, scanning patterns, and initial surface conditions on surface roughness were analyzed.

  20. The sagrada familia: A daily whisper of the spirit

    Science.gov (United States)

    Campos, Arturo

    2002-11-01

    Sounds from the top of the Temple; songs of loyals going beyond the city, sounds of the rustic forms of the spaces for the soul; reality and miracle in just one voice, voice of religion for participation; mystery, mysticism, meditation, happiness, music and songs, bells and church towers, choirs and pulpits, religion and city. The religious architecture of Gaudi is involved by mystic sounds, real or imaginary sounds, whispers almost imperceptibles and sonorous surprises in the journeys destined to peace and spiritual calm. The Sagrada Familia in Barcelona is a Temple where the sonorous itineraries will exist and where the acoustic design of choirs, bells and bell towers was an essential idea of Antoni Gaudi. A living building with its voice singing with the people a song which will take in the whole city; ringing bells and bell towers crossing the sky and sending music, view and hearing of all the people to the new cathedral, a symbol to guide pilgrimages, ceremonies, songs and festivals. The Sagrada Familia and Barcelona, a union that Gaudi wanted to turn in total and where the acoustic design will be transformed in a daily murmur, highly spiritual. (To be presented in Spanish.)

  1. Plutonium Critical Mass Curve Comparison to Mass at Upper Subcritical Limit (USL) Using Whisper

    Energy Technology Data Exchange (ETDEWEB)

    Alwin, Jennifer Louise [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Monte Carlo Codes; Zhang, Ning [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Nuclear Criticality Safety Division

    2016-09-27

    Whisper is computational software designed to assist the nuclear criticality safety analyst with validation studies with the MCNP® Monte Carlo radiation transport package. Standard approaches to validation rely on the selection of benchmarks based upon expert judgment. Whisper uses sensitivity/uncertainty (S/U) methods to select relevant benchmarks to a particular application or set of applications being analyzed. Using these benchmarks, Whisper computes a calculational margin. Whisper attempts to quantify the margin of subcriticality (MOS) from errors in software and uncertainties in nuclear data. The combination of the Whisper-derived calculational margin and MOS comprise the baseline upper subcritical limit (USL), to which an additional margin may be applied by the nuclear criticality safety analyst as appropriate to ensure subcriticality. A series of critical mass curves for plutonium, similar to those found in Figure 31 of LA-10860-MS, have been generated using MCNP6.1.1 and the iterative parameter study software, WORM_Solver. The baseline USL for each of the data points of the curves was then computed using Whisper 1.1. The USL was then used to determine the equivalent mass for plutonium metal-water system. ANSI/ANS-8.1 states that it is acceptable to use handbook data, such as the data directly from the LA-10860-MS, as it is already considered validated (Section 4.3 4) “Use of subcritical limit data provided in ANSI/ANS standards or accepted reference publications does not require further validation.”). This paper attempts to take a novel approach to visualize traditional critical mass curves and allows comparison with the amount of mass for which the keff is equal to the USL (calculational margin + margin of subcriticality). However, the intent is to plot the critical mass data along with USL, not to suggest that already accepted handbook data should have new and more rigorous requirements for validation.

  2. Speech Enhancement Algorithm Based on MMSE Short Time Spectral Amplitude in Whispered Speech

    Institute of Scientific and Technical Information of China (English)

    Zhi-Heng Lu; Huai-Zong Shao; Tai-Liang Ju

    2009-01-01

    An improved method based on minimum mean square error-short time spectral amplitude (MMSE-STSA) is proposed to cancel background noise in whispered speech. Using the acoustic character of whispered speech, the algorithm can track the change of non-stationary background noise effectively. Compared with original MMSE-STSA algorithm and method in selectable mode Vo-coder (SMV), the improved algorithm can further suppress the residual noise for low signal-to-noise radio (SNR) and avoid the excessive suppression. Simulations show that under the non-stationary noisy environment, the proposed algorithm can not only get a better performance in enhancement, but also reduce the speech distortion.

  3. Buffer layers for high-Tc thin films on sapphire

    Science.gov (United States)

    Wu, X. D.; Foltyn, S. R.; Muenchausen, R. E.; Cooke, D. W.; Pique, A.; Kalokitis, D.; Pendrick, V.; Belohoubek, E.

    1992-01-01

    Buffer layers of various oxides including CeO2 and yttrium-stabilized zirconia (YSZ) have been deposited on R-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa2Cu3O(7-delta) (YBCO) thin films. An ion beam channeling minimum yield of about 3 percent was obtained in the CeO2 layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO2 was found to be the best one for YBCO thin films on R-plane sapphire. High Tc and Jc were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were about 4 mOmega at 77 K and 25 GHz.

  4. Study on the Anisotropy of Meniscus in the Growing Sapphire

    Institute of Scientific and Technical Information of China (English)

    YAO Tai; ZUO Hong-bo; HAN Jie-cai; MENG Song-he; ZHANG Ming-fu; LI Chang-qing; Grigoryan Benik

    2006-01-01

    This study is aimed at predicting the relationship between the meniscus and the quality of the sapphire crystals produced by the micro-pulling and shoulder at cooled center (SAPMIC) technique. As with different orientations, the shapes of the meniscus vary, so an investigation into the anisotropy of the meniscus shapes is very important for the final quality of the sapphire crystal. An effective model to describe meniscus shapes and their formation process has been presented. The model has been applied to a sapphire crystal of 200 mm diameter in order to check its reliability. The results show that the model proves to be useful for forecasting the final shapes of the sapphire crystal made by the SAPMIC technique.

  5. Buffer layers for high-Tc thin films on sapphire

    Science.gov (United States)

    Wu, X. D.; Foltyn, S. R.; Muenchausen, R. E.; Cooke, D. W.; Pique, A.; Kalokitis, D.; Pendrick, V.; Belohoubek, E.

    1992-01-01

    Buffer layers of various oxides including CeO2 and yttrium-stabilized zirconia (YSZ) have been deposited on R-plane sapphire. The orientation and crystallinity of the layers were optimized to promote epitaxial growth of YBa2Cu3O(7-delta) (YBCO) thin films. An ion beam channeling minimum yield of about 3 percent was obtained in the CeO2 layer on sapphire, indicating excellent crystallinity of the buffer layer. Among the buffer materials used, CeO2 was found to be the best one for YBCO thin films on R-plane sapphire. High Tc and Jc were obtained in YBCO thin films on sapphire with buffer layers. Surface resistances of the YBCO films were about 4 mOmega at 77 K and 25 GHz.

  6. Nanostructured sapphire optical fiber for sensing in harsh environments

    Science.gov (United States)

    Chen, Hui; Liu, Kai; Ma, Yiwei; Tian, Fei; Du, Henry

    2017-05-01

    We describe an innovative and scalable strategy of transforming a commercial unclad sapphire optical fiber to an allalumina nanostructured sapphire optical fiber (NSOF) that overcomes decades-long challenges faced in the field of sapphire fiber optics. The strategy entails fiber coating with metal Al followed by subsequent anodization to form anodized alumina oxide (AAO) cladding of highly organized pore channel structure. We show that Ag nanoparticles entrapped in AAO show excellent structural and morphological stability and less susceptibility to oxidation for potential high-temperature surface-enhanced Raman Scattering (SERS). We reveal, with aid of numerical simulations, that the AAO cladding greatly increases the evanescent-field overlap both in power and extent and that lower porosity of AAO results in higher evanescent-field overlap. This work has opened the door to new sapphire fiber-based sensor design and sensor architecture.

  7. Neutron Transmission through Sapphire Crystals: Experiments and Simulations

    OpenAIRE

    Rantsiou, Emmanouela; Filges, Uwe; Panzner, Tobias; Klinkby, Esben Bryndt

    2013-01-01

    Sapphire crystals are excellent filters of fast neutrons, while at the same time exhibit moderate to very little absorption at smaller energies. We have performed an extensive series of measurements in order to quantify the above effect. Alongside our experiments, we have performed a series of simulations, in order to reproduce the transmission of cold neutrons through sapphire crystals. Thosesimulations were part of the effort of validating and improving the newly developed interface between...

  8. Investigation of sapphire detector designed for single particle detection

    Energy Technology Data Exchange (ETDEWEB)

    Karacheban, Olena; Hempel, Maria [DESY, Zeuthen (Germany); Brandenburg University of Technology, Cottbus (Germany); Afanaciev, Konstantin [NCPHEP, Minsk (Belarus); Henschel, Hans; Lange, Wolfgang; Leonard, Jessica [DESY, Zeuthen (Germany); Levy, Itamar [Tel Aviv University, Tel Aviv (Israel); Lohmann, Wolfgang [Brandenburg University of Technology, Cottbus (Germany); CERN, Geneva (Switzerland); Novgorodova, Olga [Technical University, Dresden (Germany); Schuwalow, Sergej [DESY, Hamburg (Germany)

    2015-07-01

    For beam halo and beam loss monitoring systems at accelerators extremely radiation hard sensors are needed. Single crystal sapphire is a promising material. Industrially grown sapphire wafers are available in large sizes, are low in cost and can be operated at room temperature. Currently sapphire sensors are used for a beam-loss monitor at FLASH,detecting bunches of particles crossing the sensors simultaneously. Here we present a multichannel detector designed for single minimum ionising particle detection using a stack of sapphire plates. The performance of the detector was studied in a 5 GeV electron beam at DESY-II. The detector was operated together with the EUDET beam telescope, which allowed the reconstruction of the position of the hits at the detector. For each sapphire plate the charge collection efficiency was measured as a function of the bias voltage and the signal size as a function of the hit position with respect to the metal electrodes. The data confirms that mainly electrons contribute to the signal. Based on these results the next generation sapphire detector will be designed.

  9. Museums and art galleries as partners for public health interventions.

    Science.gov (United States)

    Camic, Paul M; Chatterjee, Helen J

    2013-01-01

    The majority of public health programmes are based in schools, places of employment and in community settings. Likewise, nearly all health-care interventions occur in clinics and hospitals. An underdeveloped area for public health-related planning that carries international implications is the cultural heritage sector, and specifically museums and art galleries. This paper presents a rationale for the use of museums and art galleries as sites for public health interventions and health promotion programmes through discussing the social role of these organisations in the health and well-being of the communities they serve. Recent research from several countries is reviewed and integrated into a proposed framework for future collaboration between cultural heritage, health-care and university sectors to further advance research, policy development and evidence-based practice.

  10. Ti : sapphire laser synchronised with femtosecond Yb pump laser via nonlinear pulse coupling in Ti : sapphire active medium

    Science.gov (United States)

    Didenko, N. V.; Konyashchenko, A. V.; Konyashchenko, D. A.; Kostryukov, P. V.; Kuritsyn, I. I.; Lutsenko, A. P.; Mavritskiy, A. O.

    2017-02-01

    A laser system utilising the method of synchronous pumping of a Ti : sapphire laser by a high-power femtosecond Yb3+-doped laser is described. The pulse repetition rate of the Ti : sapphire laser is successfully locked to the repetition rate of the Yb laser for more than 6 hours without the use of any additional electronics. The measured timing jitter is shown to be less than 1 fs. A simple qualitative model addressing the synchronisation mechanism utilising the cross-phase modulation of oscillation and pump pulses within a Ti : sapphire active medium is proposed. Output parameters of the Ti : sapphire laser as functions of its cavity length are discussed in terms of this model.

  11. Blindness, art and exclusion in museums and galleries

    OpenAIRE

    Candlin, Fiona

    2003-01-01

    Drawing on interviews with blind people, this paper examines both their exclusion from museums and galleries and their responses to the art educational provision which is specifically designed to remedy that marginalisation. Blind visitors’ responses to these educational projects was polarised; respondents were either highly critical or very enthusiastic. This paper begins by outlining the interviewees’ criticisms which included, education officers’ misconception of how touch facilitates lear...

  12. GaN on sapphire mesa technology

    Energy Technology Data Exchange (ETDEWEB)

    Herfurth, Patrick; Men, Yakiv; Kohn, Erhard [Institute of Electron Devices and Circuits, Ulm University, Albert-Einstein Allee 45, 89081 Ulm (Germany); Roesch, Rudolph [Institute of Optoelectronics, Albert-Einstein Allee 45, 89081 Ulm (Germany); Carlin, Jean-Francois; Grandjean, Nicolas [Laboratory of Advanced Semiconductors for Photonics and Electronics, Ecole Polytechnique Federal de Lausanne, 1015 Lausanne (Switzerland)

    2012-03-15

    This contribution reports on a GaN on sapphire mesa technology for lattice matched InAlN/GaN HEMTs similar to a silicon on insulator technology. Ultrathin buffer layers between 500 nm and 100 nm have been deep mesa etched down to the substrate to avoid cross talk between devices through the buffer and provide full transparency outside the active device area (of special interest to biochemical sensor applications).The heterostructure characteristics were: N{sub S}> 1.6 x 10{sup 13} cm{sup -2}, R{sub sh}< 600 {omega}/{open_square}. 0.25 {mu}m gate length HEMT device characteristics are moderate, but essentially similar down to 200 nm buffer thickness. Devices on 100 nm buffer layer are still difficult to reproduce. I{sub on}/I{sub off} was up to 10{sup 9} and sub-threshold slopes down to 90 mV/dec (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Ghost Whisperer's Ghost in the Machine: An example of pop cultural representation of virtual worlds

    DEFF Research Database (Denmark)

    Reinhard, CarrieLynn D.

    2009-01-01

    Analysis of an episode of the CBS series "Ghost Whisperer" for how it depicts a) what is a virtual world and b) the tensions that are involved in discussing the uses and effects of a virtual world.  Discussion focuses on the overriding negative reception of virtual worlds in popular culture due t...

  14. The whispered voice: The best test for screening for hearing impairment in general practice?

    NARCIS (Netherlands)

    Eekhof, J.A.H.; Bock, G.H. de; Laat, J.A.P.M. de; Dap, R.; Schaapveld, K.; Springer, M.P.

    1996-01-01

    Hearling loss is an important health problem in the elderly which sometimes leads to social isolation. In a study with 62 patients, the diagnostic value of four simple tests for screening for hearing loss in general practice was examined. When paying attention to the loudness of the whispering, the

  15. Whisper, a resonance sounder and wave analyser: Performances and perspectives for the Cluster mission

    DEFF Research Database (Denmark)

    Decreau, P.M.E.; Fergeau, P.; KrannoselsKikh, V.

    1997-01-01

    The WHISPER sounder on the Cluster spacecraft is primarily designed to provide an absolute measurement of the total plasma density within the range 0.2-80 cm(-3). This is achieved by means of a resonance sounding technique which has already proved successful in the regions to be explored. The wav...

  16. Whisper, a resonance sounder and wave analyser: Performances and perspectives for the Cluster mission

    DEFF Research Database (Denmark)

    Decreau, P.M.E.; Fergeau, P.; KrannoselsKikh, V.;

    1997-01-01

    The WHISPER sounder on the Cluster spacecraft is primarily designed to provide an absolute measurement of the total plasma density within the range 0.2-80 cm(-3). This is achieved by means of a resonance sounding technique which has already proved successful in the regions to be explored. The wav...

  17. A peek into the history of sapphire crystal growth

    Science.gov (United States)

    Harris, Daniel C.

    2003-09-01

    After the chemical compositions of sapphire and ruby were unraveled in the middle of the 19th century, chemists set out to grow artificial crystals of these valuable gemstones. In 1885 a dealer in Geneva began to sell ruby that is now believed to have been created by flame fusion. Gemnologists rapidly concluded that the stones were artificial, but the Geneva ruby stimulated A. V. L. Verneuil in Paris to develop a flame fusion process to produce higher quality ruby and sapphire. By 1900 there was brisk demand for ruby manufactured by Verneuil's method, even though Verneuil did not publicly announce his work until 1902 and did not publish details until 1904. The Verneuil process was used with little alteration for the next 50 years. From 1932-1953, S. K. Popov in the Soviet Union established a capability for manufacturing high quality sapphire by the Verneuil process. In the U.S., under government contract, Linde Air Products Co. implemented the Verneuil process for ruby and sapphire when European sources were cut off during World War II. These materials were essential to the war effort for jewel bearings in precision instruments. In the 1960s and 1970s, the Czochralski process was implemented by Linde and its successor, Union Carbide, to make higher crystal quality material for ruby lasers. Stimulated by a government contract for structural fibers in 1966, H. LaBelle invented edge-defined film-fed growth (EFG). The Saphikon company, which is currently owned by Saint-Gobain, evolved from this effort. Independently and simultaneously, Stepanov developed edge-defined film-fed growth in the Soviet Union. In 1967 F. Schmid and D. Viechnicki at the Army Materials Research Lab grew sapphire by the heat exchanger method (HEM). Schmid went on to establish Crystal Systems, Inc. around this technology. Rotem Industries, founded in Israel in 1969, perfected the growth of sapphire hemispheres and near-net-shape domes by gradient solidification. In the U.S., growth of near

  18. Evolution of the sapphire industry: Rubicon Technology and Gavish

    Science.gov (United States)

    Harris, Daniel C.

    2009-05-01

    A. Verneuil developed flame fusion to grow sapphire and ruby on a commercial scale around 1890. Flame fusion was further perfected by Popov in the Soviet Union in the 1930s and by Linde Air Products Co. in the U.S. during World War II. Union Carbide Corp., the successor to Linde, developed Czochralski crystal growth for sapphire laser materials in the 1960s. Stepanov in the Soviet Union published his sapphire growth method in 1959. Edge-Defined Film-Fed Growth (EFG), which is similar to the Stepanov method, was developed by H. Labelle in the U. S. in the 1960s and 1970s. The Heat Exchanger Method (HEM), invented by F. Schmid and D. Viechnicki in 1967 was commercialized in the 1970s. Gradient solidification was invented in Israel in the 1970s by J. Makovsky. The Horizontal Directional Solidification Method (HDSM) proposed by Kh. S. Bagdasorov in the Soviet Union in the 1960s was further developed at the Institute for Single Crystals in Ukraine. Kyropoulos growth of sapphire, known as GOI crystal growth in the Soviet Union, was developed by M. Musatov at the State Optical Institute in St. Petersburg in the 1970s and 1980s. At the Institute for Single Crystals in Ukraine, E. Dobrovinskaya characterized Verneuil, Czochralsky, Bagdasarov, and GOI sapphire. In 1995, she emigrated to the United States and joined S&R Rubicon, founded near Chicago by R. Mogilevsky initially to import sapphire and ruby. Mogilevsky began producing sapphire by the Kyropoulos method in 1999. In 2000 the company name was changed to Rubicon Technology. Today, Dobrovinskaya is Chief Scientist and Rubicon produces high quality Kyropoulos sapphire substrates for solid-state lighting. In 1995, H. Branover of Ben Gurion University and a sole investor founded Gavish, which is Hebrew for "crystal." They invited another veteran of the Ukrainian Institute for Single Crystals, V. Pishchik, to become Chief Scientist. Under Pishchik's technical leadership and J. Sragowicz's business leadership, Gavish now

  19. Scaling STI's sapphire cryocooler for applications requiring higher heat loads

    Science.gov (United States)

    Karandikar, Abhijit; Fiedler, Andreas

    2012-06-01

    Superconductor Technologies Inc. (STI) developed the Sapphire cryocooler specifically for the SuperLink® product; a high performance superconducting Radio Frequency (RF) front-end receiver used by wireless carriers such as Verizon Wireless and AT&T to improve network cell coverage and data speeds. STI has built and deployed over 6,000 systems operating 24 hours a day (24/7), 7 days a week in the field since 1999. Sapphire is an integrated free piston Stirling cycle cryocooler with a cooling capacity of 5 Watts at 77 Kelvin (K) with less than 100 Watts (W) input power. It has a field-proven Mean Time Between Failure (MTBF) of well over 1 million hours, requires zero maintenance and has logged over 250 million cumulative runtime hours. The Sapphire cooler is built on a scalable technology platform, enabling the design of machines with cooling capacities greater than 1 kilowatt (kW). This scalable platform also extends the same outstanding attributes as the Sapphire cooler, namely high reliability, zero maintenance, and compact size - all at a competitive cost. This paper will discuss emerging applications requiring higher heat loads and these attributes, describe Sapphire, and show a preliminary concept of a scaled machine with a 100 W cooling capacity.

  20. Voltage-Controlled Sapphire Oscillator: Design, Development, and Preliminary Performance

    Science.gov (United States)

    Wang, R. T.; Dick, G. J.; Tjoelker, R. L.

    2007-08-01

    We present the design for a new short-term frequency standard, the voltage-controlled sapphire oscillator, as a practical and lower-cost alternative to a cryogenic sapphire oscillator operating at liquid helium temperatures. Performance goals are a frequency stability of 1 x 10^-14 (1 second equal to or less than tau equal to or less than 100 seconds), more than 2 years of continuous operation, and practical operability. Key elements include the sapphire resonator, low-power and long-life cryocooler, frequency compensation method, and cryo-Pound design. We report the design verification, experimental results, and test results of the cryocooler environmental sensitivity, as well as a preliminary stability measurement.

  1. Clinical Application of the Sapphire Unfolder Lens Injection System

    Institute of Scientific and Technical Information of China (English)

    Weiai Guo; Danying Zheng; Zhenyu Li; Yiyong Qian; Zhenping Zhang

    2002-01-01

    Purpose: To summarize the clinical experience of 300 cases using the Sapphire unfloder intraocular lens (IOL) injection system.Methods: After the standard phacoemulsification, an AR40e IOL was implanted using the Sapphire Unfolder. The involved problems during and after the operation were observed and analyzed.Results:The complications occurred during the operation including the crack at the haptic-optic junction in 2 cases, slight kink in the haptic in 5 cases, IOL clamp into the cartridge in 2 cases, posterior capsular rupture in 2 cases and endothelium damage in the central small area in 4 cases. All the patients recovered successfully with IOLs in good position.Conclusion: IOL implantation with the Sapphire Unfolder led to no serious complications and got the satisfactory results.

  2. InfoGallery: Informative Arts Services for Physical Library Spaces

    DEFF Research Database (Denmark)

    Grønbæk, Kaj; Rohde, Anne; Sundararajah, Balasuthas

    2006-01-01

    Much focus in digital libraries research has been devoted to new online services rather than services for the visitors in the physical library. This paper describes InfoGallery, which is a web-based infrastructure for enriching the physical library space with informative art "exhibitions" of digi...... structure, an editor application and a variety of display clients. The paper discusses the design of the infrastructure and its utilization of RSS, podcasts and manually edited news. Applications in the library domain are described and the experiences are discussed....

  3. Blocks and residual stresses in shaped sapphire single crystals

    Science.gov (United States)

    Krymov, V. M.; Nosov, Yu. G.; Bakholdin, S. I.; Maslov, V. N.; Shul‧pina, I. L.; Nikolaev, V. I.

    2017-01-01

    The formation of blocks and residual stresses in shaped sapphire crystals grown from the melt by the Stepanov method (EFG) has been studied. The probability of block formation is higher for the growth along the c axis compared to that grown in the a-axis direction. The distribution of residual stress in sapphire crystals of tubular, rectangular and round cross section was measured by the conoscopy method. It was found that the magnitude of the residual stress increases from the center to the periphery of the crystal and reaches up to about 20 MPa. Residual stress tensor components for solid round rod and tubular single crystals were determined by numerical integration.

  4. Inversion domains in AlN grown on (0001) sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Jasinski, J.; Liliental-Weber, Z.; Paduano, Q.S.; Weyburne, D.W.

    2003-08-25

    Al-polarity inversion domains formed during AlN layer growth on (0001) sapphire were identified using transmission electron microscopy (TEM). They resemble columnar inversion domains reported for GaN films grown on (0001) sapphire. However, for AlN, these columns have a V-like shape with boundaries that deviate by 2 {+-} 0.5{sup o} from the c-axis. TEM identification of these defects agrees with the post-growth surface morphology as well as with the microstructure revealed by etching in hot aqueous KOH.

  5. Sea level characterization of a 1100 g sapphire bolometer

    CERN Document Server

    Pécourt, S; Bobin, C; Coron, N; Jesus, M D; Hadjout, J P; Leblanc, J W; Marcillac, P D

    1999-01-01

    A first characterization of a 1100 g sapphire bolometer, performed at sea level and at a working temperature of 40 mK, is presented. Despite perturbations coming from the high-radioactive background and cosmic rays, calibration spectra could be achieved with an internal alpha source and a sup 5 sup 7 Co gamma-ray source: the experimental threshold is 25 keV, while the FWHM resolution is 17.4 keV for the 122 keV peak. Possible heat release effects are discussed, and a new limit of 9x10 sup - sup 1 sup 4 W/g is obtained for sapphire.

  6. The Art Gallery/La Galeria de Arte: An Exhibition of Transformation.

    Science.gov (United States)

    Biagi, Juliet

    2001-01-01

    Describes the development of an art gallery within an urban elementary school, examining its impact on diverse students and their social interactions at school and home. The gallery had a positive impact on students (improved self-esteem, motivation, and appreciation of others); the school (transformation of the physical space and appreciation of…

  7. The Art Gallery/La Galeria de Arte: An Exhibition of Transformation.

    Science.gov (United States)

    Biagi, Juliet

    2001-01-01

    Describes the development of an art gallery within an urban elementary school, examining its impact on diverse students and their social interactions at school and home. The gallery had a positive impact on students (improved self-esteem, motivation, and appreciation of others); the school (transformation of the physical space and appreciation of…

  8. Perceptions of Pre-Service Teachers Value of Art Museums and Galleries

    Science.gov (United States)

    Lemon, Narelle; Garvis, Susanne

    2014-01-01

    Art museums and galleries provide many educational opportunities for generalist classroom teachers to engage in learning experiences with students. Beliefs about engagement with art museums and galleries can begin in teacher education programs. This paper explores the beliefs of pre-service teachers in a Bachelor of Education (primary) program in…

  9. Guarding curvilinear art galleries with vertex or point guards

    CERN Document Server

    Karavelas, Menelaos I

    2008-01-01

    One of the earliest and most well known problems in computational geometry is the so-called art gallery problem. The goal is to compute the minimum possible number guards placed on the vertices of a simple polygon in such a way that they cover the interior of the polygon. In this paper we consider the problem of guarding an art gallery which is modeled as a polygon with curvilinear walls. Our main focus is on polygons the edges of which are convex arcs pointing towards the exterior or interior of the polygon (but not both), named piecewise-convex and piecewise-concave polygons. We prove that, in the case of piecewise-convex polygons, if we only allow vertex guards, $\\lfloor\\frac{4n}{7}\\rfloor-1$ guards are sometimes necessary, and $\\lfloor\\frac{2n}{3}\\rfloor$ guards are always sufficient. Moreover, an $O(n\\log{}n)$ time and $O(n)$ space algorithm is described that produces a vertex guarding set of size at most $\\lfloor\\frac{2n}{3}\\rfloor$. When we allow point guards the afore-mentioned lower bound drops down ...

  10. Change in equilibrium position of misfit dislocations at the GaN/sapphire interface by Si-ion implantation into sapphire. II. Electron energy loss spectroscopic study

    Directory of Open Access Journals (Sweden)

    Sung Bo Lee

    2015-07-01

    Full Text Available In Part I, we have shown that the addition of Si into sapphire by ion implantationmakes the sapphire substrate elastically softer than for the undoped sapphire. The more compliant layer of the Si-implanted sapphire substrate can absorb the misfit stress at the GaN/sapphire interface, which produces a lower threading-dislocation density in the GaN overlayer. Here in Part II, based on experimental results by electron energy loss spectroscopy and a first-principle molecular orbital calculation in the literature, we suggest that the softening effect of Si results from a reduction of ionic bonding strength in sapphire (α-Al2O3 with the substitution of Si for Al.

  11. Structure of shaped sapphire grown from multicapillary dies

    Science.gov (United States)

    Dobrovinskaya, E. R.; Litvinov, L. A.; Pischik, V. V.

    1990-07-01

    Peculiarities in grain structure development have been studied in sapphire crystals grown with multicapillary channels in the die to feed melt to the crystallization zone. A new mechanism of grain boundary formation based on gas-bubble collapse at the crystal-melt interface is proposed.

  12. Single-transverse-mode Ti:sapphire rib waveguide laser

    NARCIS (Netherlands)

    Grivas, C.; Shepherd, D.P.; May-Smith, T.C.; Eason, R.W.; Pollnau, M.

    2005-01-01

    Laser operation of Ti:sapphire rib waveguides fabricated using photolithography and ion beam etching in pulsed laser deposited layers is reported. Polarized laser emission was observed at 792.5 nm with an absorbed pump power threshold of 265 mW, which is more than a factor of 2 lower in comparison t

  13. Neurosurgery contact handheld probe based on sapphire shaped crystal

    Science.gov (United States)

    Shikunova, I. A.; Stryukov, D. O.; Rossolenko, S. N.; Kiselev, A. M.; Kurlov, V. N.

    2017-01-01

    A handheld contact probe based on sapphire shaped crystal is developed for intraoperative spectrally-resolved optical diagnostics, laser coagulation and aspiration of malignant brain tissue. The technology was integrated into the neurosurgical workflow for intraoperative real-time identification and removing of invasive brain cancer.

  14. Temperature-modulated annealing of c-plane sapphire for long-range-ordered atomic steps

    Science.gov (United States)

    Yatsui, Takashi; Kuribara, Kazunori; Sekitani, Tsuyoshi; Someya, Takao; Yoshimoto, Mamoru

    2016-03-01

    High-quality single-crystalline sapphire is used to prepare various semiconductors because of its thermal stability. Here, we applied the tempering technique, which is well known in the production of chocolate, to prepare a sapphire substrate. Surprisingly, we successfully realised millimetre-range ordering of the atomic step of the sapphire substrate. We also obtained a sapphire atomic step with nanometre-scale uniformity in the terrace width and atomic-step height. Such sapphire substrates will find applications in the preparation of various semiconductors and devices.

  15. Integrated Optical Pumping of Cr & Ti-Doped Sapphire Substrates With III-V Nitride Materials

    Science.gov (United States)

    2005-08-24

    the Cr in sapphire could also permit the construction of white light LEDs . Ultimately, an integrated III-V Nitride optical pump for Ti:Sapphire could...substrates by MOCVD. 2. Characterization of doped sapphire/ InGaN structures byPL to simulate electrical injection by laser or LED device structures Part 2 1...Cr:sapphire substrate. Solid line is the spectrum of blue and red light emitted by InGaN LED epitaxially grown on Cr:sapphire substrate. The light was collected

  16. Convergent structure and function of mycelial galleries in two unrelated Neotropical plant-ants.

    Science.gov (United States)

    Mayer, V E; Lauth, J; Orivel, J

    2017-01-01

    The construction process and use of galleries by Azteca brevis (Myrmicinae: Dolichoderinae) inhabiting Tetrathylacium macrophyllum (Salicaceae) were compared with Allomerus decemarticulatus (Myrmicinae: Solenopsidini) galleries on Hirtella physophora (Chrysobalanaceae). Though the two ant species are phylogenetically distant, the gallery structure seems to be surprisingly similar and structurally convergent: both are pierced with numerous holes and both ant species use Chaetothyrialean fungi to strengthen the gallery walls. Al. decemarticulatus is known to use the galleries for prey capture and whether this is also the case for Az. brevis was tested in field experiments. We placed Atta workers as potential prey/threat on the galleries and recorded the behaviour of both ant species. We found considerable behavioural differences between them: Al. decemarticulatus was quicker and more efficient at capture than was Az. brevis. While most Atta workers were captured after the first 5 min by Al. decemarticulatus, significantly fewer were captured by Az. brevis even after 20 min. Moreover, the captured Atta were sometimes simply discarded and not taken to the nest by Az. brevis. As a consequence, the major function of the galleries built by Az. brevis may, therefore, be defense against intruders in contrast to Al. decemarticulatus which uses them mainly for prey capture. This may be due to a higher need for protein in Al. decemarticulatus compared to coccid-raising Az. brevis.

  17. Video gallery of educational lectures integrated in faculty's portal

    Directory of Open Access Journals (Sweden)

    Jaroslav Majerník

    2013-05-01

    Full Text Available This paper presents a web based educational video-clips exhibition created to share various archived lectures for medical students, health care professionals as well as for general public. The presentation of closely related topics was developed as video gallery and it is based solely on free or open source tools to be available for wide academic and/or non-commercial use. Even if the educational video records can be embedded in any websites, we preferred to use our faculty’s portal, which should be a central point to offer various multimedia educational materials. The system was integrated and tested to offer open access to infectology lectures that were captured and archived from live-streamed sessions and from videoconferences.

  18. Staging scientific controversies: a gallery test on science museums' interactivity.

    Science.gov (United States)

    Yaneva, Albena; Rabesandratana, Tania Mara; Greiner, Birgit

    2009-01-01

    The "transfer" model in science communication has been addressed critically from different perspectives, while the advantages of the interactive model have been continuously praised. Yet, little is done to account for the specific role of the interactive model in communicating "unfinished science." The traditional interactive methods in museums are not sufficient to keep pace with rapid scientific developments. Interactive exchanges between laypeople and experts are thought mainly through the lens of a dialogue that is facilitated and framed by the traditional "conference room" architecture. Drawing on the results of a small-scale experiment in a gallery space, we argue for the need for a new "architecture of interaction" in museum settings based on art installation and simulation techniques, which will enhance the communication potentials of science museums and will provide conditions for a fruitful even-handed exchange of expert and lay knowledge.

  19. Single-Crystal Sapphire Optical Fiber Sensor Instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Pickrell, Gary [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Scott, Brian [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Wang, Anbo [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States); Yu, Zhihao [Virginia Polytechnic Inst. & State Univ., Blacksburg, VA (United States)

    2013-12-31

    This report summarizes technical progress on the program “Single-Crystal Sapphire Optical Fiber Sensor Instrumentation,” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. This project was completed in three phases, each with a separate focus. Phase I of the program, from October 1999 to April 2002, was devoted to development of sensing schema for use in high temperature, harsh environments. Different sensing designs were proposed and tested in the laboratory. Phase II of the program, from April 2002 to April 2009, focused on bringing the sensor technologies, which had already been successfully demonstrated in the laboratory, to a level where the sensors could be deployed in harsh industrial environments and eventually become commercially viable through a series of field tests. Also, a new sensing scheme was developed and tested with numerous advantages over all previous ones in Phase II. Phase III of the program, September 2009 to December 2013, focused on development of the new sensing scheme for field testing in conjunction with materials engineering of the improved sensor packaging lifetimes. In Phase I, three different sensing principles were studied: sapphire air-gap extrinsic Fabry-Perot sensors; intensity-based polarimetric sensors; and broadband polarimetric sensors. Black body radiation tests and corrosion tests were also performed in this phase. The outcome of the first phase of this program was the selection of broadband polarimetric differential interferometry (BPDI) for further prototype instrumentation development. This approach is based on the measurement of the optical path difference (OPD) between two orthogonally polarized light beams in a single-crystal sapphire disk. At the beginning of Phase II, in June 2004, the BPDI sensor was tested at the Wabash River coal gasifier

  20. Fungus symbionts colonizing the galleries of the ambrosia beetle Platypus quercivorus.

    Science.gov (United States)

    Endoh, Rikiya; Suzuki, Motofumi; Okada, Gen; Takeuchi, Yuko; Futai, Kazuyoshi

    2011-07-01

    Isolations were made to determine the fungal symbionts colonizing Platypus quercivorus beetle galleries of dead or dying Quercus laurifolia, Castanopsis cuspidata, Quercus serrata, Quercus crispula, and Quercus robur. For these studies, logs from oak wilt-killed trees were collected from Kyoto Prefecture, Japan. Fungi were isolated from the: (1) entrances of beetle galleries, (2) vertical galleries, (3) lateral galleries, and (4) the larval cradle of P. quercivorus in each host tree. Among the fungus colonies which appeared on YM agar plates, 1,219 were isolated as the representative isolates for fungus species inhabiting in the galleries based on their cultural characteristics. The validity of the visual classification of the fungus colonies was checked and if necessary properly corrected using microsatellite-primed PCR fingerprints. The nucleotide sequence of the D1/D2 region of the large subunit nuclear rRNA gene detected 38 fungus species (104 strains) of which three species, i.e., Candida sp. 3, Candida kashinagacola (both yeasts), and the filamentous fungus Raffaelea quercivora were isolated from all the tree species. The two yeasts were most prevalent in the interior of galleries, regardless of host tree species, suggesting their close association with the beetle. A culture-independent method, terminal restriction fragment length polymorphism (T-RFLP) analysis was also used to characterize the fungus flora of beetle galleries. T-RFLP patterns showed that yeast species belonging to the genus Ambrosiozyma frequently occurred on the gallery walls along with the two Candida species. Ours is the first report showing the specific fungi inhabiting the galleries of a platypodid ambrosia beetle.

  1. A Near-Infrared Spectroscopy Study on Cortical Hemodynamic Responses to Normal and Whispered Speech in 3- to 7-Year-Old Children

    Science.gov (United States)

    Remijn, Gerard B.; Kikuchi, Mitsuru; Yoshimura, Yuko; Shitamichi, Kiyomi; Ueno, Sanae; Tsubokawa, Tsunehisa; Kojima, Haruyuki; Higashida, Haruhiro; Minabe, Yoshio

    2017-01-01

    Purpose: The purpose of this study was to assess cortical hemodynamic response patterns in 3- to 7-year-old children listening to two speech modes: normally vocalized and whispered speech. Understanding whispered speech requires processing of the relatively weak, noisy signal, as well as the cognitive ability to understand the speaker's reason for…

  2. Ti:sapphire laser with long-pulse lamp pumping

    Science.gov (United States)

    Koselja, Michael P.; Kubelka, Jiri; Kvapil, Jiri

    1992-06-01

    Lamp pumping of Ti:Sapphire has some advantages over laser pumping and represents some interest due to possible applications. The paper will present laser behavior of Ti:Sapphire under very long lamp pulse pumping. Pulse lamp duration (FWHM) was more than 100 times greater than the lifetime of Ti3+. Output energy with no tuning element was achieved greater than 1.5 J with 0.12% electrical-to-optical efficiency. Dimensions of the rod used was 7 mm in diameter and 148 mm in length. The doping level of Ti3+ was 0.09% Ti2O3 in the rod. Tuning characteristics with different tuning elements are also presented. Further development to obtain CW lamp pumping operation will be discussed.

  3. A GRASP for Next Generation Sapphire Image Acquisition Scheduling

    Directory of Open Access Journals (Sweden)

    Yang Wang

    2016-01-01

    Full Text Available This paper investigates an image acquisition scheduling problem for a Canadian surveillance-of-space satellite named Sapphire that takes images of deep space Earth-orbiting objects. For a set of resident space objects (RSOs that needs to be imaged within the time horizon of one day, the Sapphire image acquisition scheduling (SIAS problem is to find a schedule that maximizes the “Figure of Merit” of all the scheduled RSO images. To address the problem, we propose an effective GRASP heuristic that alternates between a randomized greedy constructive procedure and a local search procedure. Experimental comparisons with the currently used greedy algorithm are presented to demonstrate the merit of the proposed algorithm in handling the SIAS problem.

  4. AlN growth on sapphire substrate by ammonia MBE

    Science.gov (United States)

    Mansurov, V. G.; Nikitin, A. Yu.; Galitsyn, Yu. G.; Svitasheva, S. N.; Zhuravlev, K. S.; Osvath, Z.; Dobos, L.; Horvath, Z. E.; Pecz, B.

    2007-03-01

    Kinetics of (0 0 0 1) Al 2O 3 surface nitridation and subsequent growth of AlN films on the sapphire substrate by ammonia molecular beam epitaxy (MBE) are investigated. Surface morphology evolution during AlN growth is studied in situ by reflection high energy electron diffraction and ex situ by atomic force microscopy. It is found that the surfaces of AlN layers thicker than 100 nm have two major features: a quite smooth background and noticeable amount of hillocks. The influence of growth conditions on the AlN surface morphology is studied in order to find a way for reducing of the hillocks density. A modification of nitridated sapphire surface by small amount of Al (1-2 monolayers) with subsequent treatment of the surface under ammonia flux is proposed. An improvement of AlN surface morphology of the layers grown on the modified surfaces is demonstrated.

  5. Measurements of prompt radiation induced conductivity of alumina and sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Hartman, E. Frederick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Zarick, Thomas Andrew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sheridan, Timothy J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Preston, Eric F. [ITT Coporation, Colorado Springs, CO (United States)

    2011-04-01

    We performed measurements of the prompt radiation induced conductivity in thin samples of Alumina and Sapphire at the Little Mountain Medusa LINAC facility in Ogden, UT. Five mil thick samples were irradiated with pulses of 20 MeV electrons, yielding dose rates of 1E7 to 1E9 rad/s. We applied variable potentials up to 1 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 1E10 and 1E9 mho/m/(rad/s), depending on the dose rate and the pulse width for Alumina and 1E7 to 6E7 mho/m/(rad/s) for Sapphire.

  6. Color Enhancement by Diffusion of Beryllium in Dark Blue Sapphire

    Institute of Scientific and Technical Information of China (English)

    Kyungj in Kim; Yongkil Ahn

    2016-01-01

    Diffusion of beryllium was performed on dark blue sapphire from China and Australia.The samples were heated with beryllium as a dopant in a furnace at 1 600 ℃ for 42 h in air.After beryllium diffusion,sam-ples were analyzed by UV-Vis,FTIR,and WD-XRF spectroscopy.After heat-treatment with Be as a catalyst, the irons of the ferrous state were changed to the ferric state.Therefore,reaction of Fe2+/Ti4+ IVCT was de-creased.The absorption peaks at 3 309 cm-1 attributed to OH radical were disappeared completely due to carry out heat treatment.Consequently,the intensity of absorption band was decreased in the visible region.Espe-cially,decreased absorption band in the vicinity of 570 nm was responsible for the lighter blue color.There-fore,we confirmed that the dark blue sapphires from China and Australia were changed to vivid blue.

  7. Ordered gold nanostructures on sapphire surfaces: Fabrication and optical investigations

    Energy Technology Data Exchange (ETDEWEB)

    Muslimov, A. E., E-mail: amuslimov@mail.ru; Butashin, A. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Konovko, A. A. [Moscow State University (Russian Federation); Smirnov, I. S. [Moscow State University of Electronics and Mathematics (Russian Federation); Roshchin, B. S.; Volkov, Yu. O. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Angelutz, A. A.; Andreev, A. V.; Shkurinov, A. P. [Moscow State University (Russian Federation); Kanevskii, V. M.; Asadchikov, V. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2012-05-15

    The possibilities of obtaining ordered gold nanoarrays on sapphire surfaces with oriented nanorelief are demonstrated. The structures are morphologically described using atomic force microscopy data. A study of the angular dependence of the reflectivity in the visible range of electromagnetic waves has revealed some features which are likely to indicate surface plasmon-polariton excitation at the air-gold interface under exposure to p-polarized radiation. The experimental results are found to be in good agreement with the theoretical calculations.

  8. Route to 100 TW Ti: Sapphire laser at repetitive mode

    Directory of Open Access Journals (Sweden)

    Teng Hao

    2013-11-01

    Full Text Available We demonstrated a 100 TW-class femtosecond Ti: sapphire laser running at repetition rate of 0.1 Hz by adding a stage amplifier in the 20 TW/10 Hz laser facility (XL-II. Pumping the new stage amplifier with the 25 J green Nd:glass laser, we successfully upgraded the laser energy to 3.4 J with duration of 29 fs, corresponding to a peak power of 117 TW.

  9. Krasotshnõje snõ Sed Arte Gallery / Irina Butjajeva

    Index Scriptorium Estoniae

    Butjajeva, Irina

    2007-01-01

    Valgevene kunstnike Jelena Shlegeli, Vladimir Gontsharuki, Dmitri Zenkovitshi ja Dmitri Masli maalinäitus "Valgevene värvilised unenäod" Tallinna galeriis Aatrium. Näitust vahendas Sed Arte Gallery, galerist Olga Ljubaskina

  10. Earth Resources Observation and Science (EROS) Center's Landsat State Mosaics Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the this gallery of images of the 50 U.S. states plus Puerto Rico as derived by Landsat data.

  11. Earth Resources Observation and Science (EROS) Center's Journey of Lewis and Clark Gallery

    Data.gov (United States)

    National Aeronautics and Space Administration — The Earth Resources Observation and Science (EROS) Center manages the this gallery of Landsat-derived images of one of the most remarkable and productive scientific...

  12. Krasotshnõje snõ Sed Arte Gallery / Irina Butjajeva

    Index Scriptorium Estoniae

    Butjajeva, Irina

    2007-01-01

    Valgevene kunstnike Jelena Shlegeli, Vladimir Gontsharuki, Dmitri Zenkovitshi ja Dmitri Masli maalinäitus "Valgevene värvilised unenäod" Tallinna galeriis Aatrium. Näitust vahendas Sed Arte Gallery, galerist Olga Ljubaskina

  13. Download - Togo Picture Gallery | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data List Contact us Togo Pic...n Download License Update History of This Database Site Policy | Contact Us Download - Togo Picture Gallery | LSDB Archive ...

  14. 75 FR 15740 - Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of Investigation

    Science.gov (United States)

    2010-03-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF LABOR Employment and Training Administration Gallery Leather Company, Inc., Trenton, ME; Notice of Termination of... Leather Company, Inc., Trenton, Maine. The petitioner has requested that the petition be...

  15. PAO Image Gallery = Public Affairs Photos of EROS Projects: 1972 - 2005

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The EROS Image Gallery collection is composed of a wide variety of images ranging from low altitude aircraft to satellite and NASA imagery; oblique photographs and...

  16. License - Togo Picture Gallery | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available his database. The license for this database is specified in the Creative Commons ...s follows: Togo Picture Gallery © DBCLS licensed under CC Attribution 4.0 International ... . The summary of the Creative Commons

  17. Implementation of the street art works into the Prague galleries programs

    OpenAIRE

    Smrčková, Jana

    2012-01-01

    This thesis focuses on making street art phenomena clearer, particularly contemporary graffiti art. This paper will help gallery owners and other art managers become familiar with the topic, and based on that knowledge, find optimal ways of introducing it into the galleries. One part of the thesis deals with the controversy of street art presentation in public, in particular the confrontation of art vs. authorities. Having considered the large scope of the topic, the thesis concentrates on Pr...

  18. Update History of This Database - Togo Picture Gallery | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data ...List Contact us Togo Picture Gallery Update History of This Database Date Update contents 2017/05/16 Togo Pi...cs.html ) is opened. About This Database Database Description Download License Update History of This Databa...se Site Policy | Contact Us Update History of This Database - Togo Picture Gallery | LSDB Archive ...

  19. Late Holocene history of savanna gallery forest from Carimagua area, Colombia.

    Science.gov (United States)

    Berrio; Hooghiemstra; Behling; van der Borg K

    2000-09-01

    The pollen record of a 65cm long core Laguna Carimagua-Bosque (4 degrees 04'N, 70 degrees 13'W) shows the late Holocene environmental history from a lake located within the gallery forest of the savannas of the Llanos Orientales of Colombia. Nine AMS radiocarbon dates of the organic deposits show that the core represents the period from ca. 1300(14)CyrBP to the present. The lake evolved from an active drainage system.During the period from ca. 1300 to 875(14)CyrBP (zone CMB-Ia), Mauritia-dominated swamp and gallery forest was present, dominated by Cecropia, and later also Acalypha and Alchornea. From 875 to 700(14)CyrBP (zone CMB-Ib), the lake was completely surrounded by gallery forest. Mauritiella and Cecropia occurred around the lake. Cecropia pioneer forest reached its greatest abundance and became gradually replaced by a more species-rich gallery forest, including Acalypha, Alchornea, Euterpe/Geonoma, Moraceae/Urticaceae, Piperaceae, and Virola. From 700 to 125(14)CyrBP (zone CMB-II), Cecropia lost its dominant role, and Mauritiella palms became more frequent. The main vegetation categories were swamp forest, gallery forest, understory elements, savanna shrubs and trees, and grass savanna. From 125(14)CyrBP to recent (zone CMB-III), the plant diversity in the gallery forest became highest, Mauritiella became very abundant, and among the savanna elements, woody Didymopanax increased.Comparison of four pollen records from savanna sites shows that pollen of savanna vegetation is markedly underrepresented in lake sediments when the lake lies within the gallery forest. As most of the drainage system of a savanna is hidden by gallery forest, we also expect a significant underrepresentation of the savanna ecosystem in river-transported pollen assemblages.

  20. SINGLE-CRYSTAL SAPPHIRE OPTICAL FIBER SENSOR INSTRUMENTATION

    Energy Technology Data Exchange (ETDEWEB)

    A. Wang; G. Pickrell; R. May

    2002-09-10

    Accurate measurement of temperature is essential for the safe and efficient operation and control of a wide range of industrial processes. Appropriate techniques and instrumentation are needed depending on the temperature measurement requirements in different industrial processes and working environments. Harsh environments are common in many industrial applications. These harsh environments may involve extreme physical conditions, such as high-temperature, high-pressure, corrosive agents, toxicity, strong electromagnetic interference, and high-energy radiation exposure. Due to these severe environmental conditions, conventional temperature sensors are often difficult to apply. This situation has opened a new but challenging opportunity for the sensor society to provide robust, high-performance, and cost-effective temperature sensors capable of operating in those harsh environments. The focus of this research program has been to develop a temperature measurement system for temperature measurements in the primary and secondary stages of slagging gasifiers. For this application the temperature measurement system must be able to withstand the extremely harsh environment posed by the high temperatures and corrosive agents present in these systems. Real-time, accurate and reliable monitoring of temperature for the coal gasification process is important to realize the full economic potential of these gasification systems. Long life and stability of operation in the high temperature environment is essential for the temperature measurement system to ensure the continuous running of the coal gasification system over the long term. In this high temperature and chemically corrosive environment, rather limited high temperature measurement techniques such as high temperature thermocouples and optical/acoustic pyrometers are available, each with their own limitations. In this research program, five different temperature sensing schemes based on the single crystal sapphire

  1. Raman lasing and Fano lineshapes in a packaged fiber-coupled whispering-gallerymode microresonator

    CERN Document Server

    Zhao, Guangming; Wang, Tao; Xu, Linhua; Long, Gui-lu; Yang, Lan

    2016-01-01

    We report Raman lasing and the optical analog of electromagnetically-induced-transparency (EIT) in a whispering-gallerymode (WGM) microtoroid resonator embedded in a low refractive index polymer matrix together with a tapered fiber coupler. The Raman laser supports both single and multimode operation with low power thresholds. Observations of Fano and EIT-like pheonomena in a packaged microresonator will enable high resolution sensors and can be used in networks where slow light process is needed. These results open the way for portable, robust, and stable WGM microlasers and laserbased sensors for applications in various environments.

  2. Conceptual Design Report. Footprint Gallery Upgrade - Civil Construction, May 1988

    Energy Technology Data Exchange (ETDEWEB)

    None

    1988-05-01

    The Footprint Gallery Complex will be enlarged and modified. The basic outline of the project will be to add 68,100 square feet of new construction, remodel 20,600 square feet of existing space, and retire by removal 17 ,500 square feet. The principal items to be addressed are: the creation of larger Main Control Rooms and Central Control Computer Rooms, the replacement of several temporary structures with permanent facilities, the provision for a growth in population of 132 people, and the creation of an intermediate sized meeting/lecture room facility. Disjointed second floor areas will be connected and made accessible to the handicapped, secure and informative viewing for visitors will be provided, and parking will be increased to match the expected growth. The new construction will provide for a more centralized concentration of systems and support personnel of the Fermilab Accelerator Division, reflecting the growth of these organizations during the last 15 years. Experiments, such as the D-Zero detector and antiproton deceleration (E760), have been assigned to the Accelerator Division for support. The associated physicists and experimenters make up the most significant component of the growth in population for which this construction will provide additional space.

  3. Leveraging Python Interoperability Tools to Improve Sapphire's Usability

    Energy Technology Data Exchange (ETDEWEB)

    Gezahegne, A; Love, N S

    2007-12-10

    The Sapphire project at the Center for Applied Scientific Computing (CASC) develops and applies an extensive set of data mining algorithms for the analysis of large data sets. Sapphire's algorithms are currently available as a set of C++ libraries. However many users prefer higher level scripting languages such as Python for their ease of use and flexibility. In this report, we evaluate four interoperability tools for the purpose of wrapping Sapphire's core functionality with Python. Exposing Sapphire's functionality through a Python interface would increase its usability and connect its algorithms to existing Python tools.

  4. Ga/Mg ratio as a new geochemical tool to differentiate magmatic from metamorphic blue sapphires

    Science.gov (United States)

    Peucat, J. J.; Ruffault, P.; Fritsch, E.; Bouhnik-Le Coz, M.; Simonet, C.; Lasnier, B.

    2007-10-01

    Using ICP-MS-LA analyses, we demonstrate that the use of the Ga/Mg ratio, in conjunction with the Fe concentration, is an efficient tool in discriminating between "metamorphic" and "magmatic" blue sapphires. Magmatic blue sapphires found in alkali basalts (e.g. southeastern Asia, China, Africa) are commonly medium-rich to rich in Fe (with average contents between 2000 and 11000 ppm), high in Ga (> 140 ppm), and low in Mg (generally 10). Conversely, metamorphic blue sapphires found in basalts (e.g. Pailin pastel) and in metamorphic terrains (e.g. Mogok, Sri Lanka, Ilakaka) are characterized by low average iron contents ( 60 ppm) with low average Ga/Mg ratios (< 10). Basaltic magmatic sapphires have Fe, Ga and Mg contents similar to those obtained for primary magmatic sapphires found in the Garba Tula syenite. This suggests that these both sets of sapphires have a possible common "syenitic" origin, as previously proposed from other criteria. In addition, plumasite-related sapphires and metamorphic sapphires also exhibit similar composition in trace elements. Based on results from the present study, we suggest that fluid circulations during a metamorphic stage produced metasomatic exchanges between mafic and acidic rocks (plumasite model), thus explaining the high Mg contents and converging Ga/Mg ratios observed in metamorphic sapphires.

  5. Shooting gallery attendance among IDUs in Tijuana and Ciudad Juarez, Mexico: correlates, prevention opportunities, and the role of the environment.

    Science.gov (United States)

    Philbin, Morgan; Pollini, Robin A; Ramos, Rebecca; Lozada, Remedios; Brouwer, Kimberly C; Ramos, Maria Elena; Firestone-Cruz, Michelle; Case, Patricia; Strathdee, Steffanie A

    2008-07-01

    We identified factors associated with shooting gallery attendance among injection drug users (IDUs) in two Mexico-US border cities. IDUs in Tijuana (n=222) and Ciudad Juarez (n=205), Mexico, who were >or=18 years and injected illicit drugs in the last month were recruited using respondent-driven sampling (RDS). An interviewer-administered survey collected sociodemographic and behavioral data. Logistic regression was used to examine correlates of shooting gallery attendance in each of the two cities. Homelessness and being arrested for syringe possession--both structural level factors--were associated with shooting gallery use in both cities. In Ciudad Juarez, younger age and having overdosed were also associated with shooting gallery use. Our study highlights the need for structural interventions that mitigate homelessness among IDUs and facilitate changes in law enforcement practices associated with shooting gallery use. Harm reduction interventions based within shooting galleries should also be considered to prevent transmission of blood-borne pathogens among IDUs.

  6. Influence of musical training on understanding voiced and whispered speech in noise.

    Science.gov (United States)

    Ruggles, Dorea R; Freyman, Richard L; Oxenham, Andrew J

    2014-01-01

    This study tested the hypothesis that the previously reported advantage of musicians over non-musicians in understanding speech in noise arises from more efficient or robust coding of periodic voiced speech, particularly in fluctuating backgrounds. Speech intelligibility was measured in listeners with extensive musical training, and in those with very little musical training or experience, using normal (voiced) or whispered (unvoiced) grammatically correct nonsense sentences in noise that was spectrally shaped to match the long-term spectrum of the speech, and was either continuous or gated with a 16-Hz square wave. Performance was also measured in clinical speech-in-noise tests and in pitch discrimination. Musicians exhibited enhanced pitch discrimination, as expected. However, no systematic or statistically significant advantage for musicians over non-musicians was found in understanding either voiced or whispered sentences in either continuous or gated noise. Musicians also showed no statistically significant advantage in the clinical speech-in-noise tests. Overall, the results provide no evidence for a significant difference between young adult musicians and non-musicians in their ability to understand speech in noise.

  7. Detection of beryllium treatment of natural sapphires by NRA

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez, P.C., E-mail: carolina.gutierrez@uam.e [Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Ynsa, M.-D.; Climent-Font, A. [Centro de Micro-Analisis de Materiales (CMAM), Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Dpto. Fisica Aplicada C-12, Universidad Autonoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Calligaro, T. [Centre de Recherche et de Restauration des musees de France C2RMF, CNRS-UMR171, 14 quai Francois Mitterrand, 75001 Paris (France)

    2010-06-15

    Since the 1990's, artificial treatment of natural sapphires (Al{sub 2}O{sub 3} crystals coloured by impurities) by diffusion of beryllium at high temperature has become a growing practice. This process permits to enhance the colour of these gemstones, and thus to increase their value. Detection of such a treatment - diffusion of tens of {mu}g/g of beryllium in Al{sub 2}O{sub 3} crystals - is usually achieved using high sensitivity techniques like laser-ablation inductively coupled plasma mass spectrometry (LA-ICP/MS) or laser-induced breakdown spectrometry (LIBS) which are unfortunately micro-destructive (leaving 50-100-{mu}m diameter craters on the gems). The simple and non-destructive alternative method proposed in this work is based on the nuclear reaction {sup 9}Be({alpha}, n{gamma}){sup 12}C with an external helium ion beam impinging on the gem directly placed in air. The 4439 keV prompt {gamma}-ray tagging Be atoms are detected with a high efficiency bismuth germanate scintillator. Beam dose is monitored using the 2235 keV prompt {gamma}-ray produced during irradiation by the aluminium of the sapphire matrix through the {sup 27}Al({alpha}, p{gamma}){sup 30}Si nuclear reaction. The method is tested on a series of Be-treated sapphires previously analyzed by LA-ICP/MS to determine the optimal conditions to obtain a peak to background appropriate to reach the required {mu}g/g sensitivity. Using a 2.8-MeV external He beam and a beam dose of 200 {mu}C, beryllium concentrations from 5 to 16 {mu}g/g have been measured in the samples, with a detection limit of 1 {mu}g/g.

  8. Detection of beryllium treatment of natural sapphires by NRA

    Science.gov (United States)

    Gutiérrez, P. C.; Ynsa, M.-D.; Climent-Font, A.; Calligaro, T.

    2010-06-01

    Since the 1990's, artificial treatment of natural sapphires (Al 2O 3 crystals coloured by impurities) by diffusion of beryllium at high temperature has become a growing practice. This process permits to enhance the colour of these gemstones, and thus to increase their value. Detection of such a treatment - diffusion of tens of μg/g of beryllium in Al 2O 3 crystals - is usually achieved using high sensitivity techniques like laser-ablation inductively coupled plasma mass spectrometry (LA-ICP/MS) or laser-induced breakdown spectrometry (LIBS) which are unfortunately micro-destructive (leaving 50-100-μm diameter craters on the gems). The simple and non-destructive alternative method proposed in this work is based on the nuclear reaction 9Be(α, nγ) 12C with an external helium ion beam impinging on the gem directly placed in air. The 4439 keV prompt γ-ray tagging Be atoms are detected with a high efficiency bismuth germanate scintillator. Beam dose is monitored using the 2235 keV prompt γ-ray produced during irradiation by the aluminium of the sapphire matrix through the 27Al(α, pγ) 30Si nuclear reaction. The method is tested on a series of Be-treated sapphires previously analyzed by LA-ICP/MS to determine the optimal conditions to obtain a peak to background appropriate to reach the required μg/g sensitivity. Using a 2.8-MeV external He beam and a beam dose of 200 μC, beryllium concentrations from 5 to 16 μg/g have been measured in the samples, with a detection limit of 1 μg/g.

  9. Ultrafast, ultrahigh-peak power Ti:sapphire laser system

    Energy Technology Data Exchange (ETDEWEB)

    Yamakawa, Koichi; Aoyama, Makoto; Matsuoka, Shinichi; Akahane, Yutaka; Kase, Teiji; Nakano, Fumihiko; Sagisaka, Akito [Advanced Photon Research Center, Kansai Research Establishment, Japan Atomic Energy Research Inst., Kizu, Kyoto (Japan)

    2001-01-01

    We review progress in the generation of multiterawatt optical pulses in the 10-fs range. We describe a design, performance and characterization of a Ti:sapphire laser system based on chirped-pulse amplification, which has produced a peak power in excess of 100-TW with sub-20-fs pulse durations and an average power of 19-W at a 10-Hz repetition rate. We also discuss extension of this system to the petawatt power level and potential applications in the relativistic, ultrahigh intensity regimes. (author)

  10. Lattice-Matched Semiconductor Layers on Single Crystalline Sapphire Substrate

    Science.gov (United States)

    Choi, Sang; King, Glen; Park, Yeonjoon

    2009-01-01

    SiGe is an important semiconductor alloy for high-speed field effect transistors (FETs), high-temperature thermoelectric devices, photovoltaic solar cells, and photon detectors. The growth of SiGe layer is difficult because SiGe alloys have different lattice constants from those of the common Si wafers, which leads to a high density of defects, including dislocations, micro-twins, cracks, and delaminations. This innovation utilizes newly developed rhombohedral epitaxy of cubic semiconductors on trigonal substrates in order to solve the lattice mismatch problem of SiGe by using trigonal single crystals like sapphire (Al2O3) as substrate to give a unique growth-orientation to the SiGe layer, which is automatically controlled at the interface upon sapphire (0001). This technology is different from previous silicon on insulator (SOI) or SGOI (SiGe on insulator) technologies that use amorphous SiO2 as the growth plane. A cubic semiconductor crystal is a special case of a rhombohedron with the inter-planar angle, alpha = 90 deg. With a mathematical transformation, all rhombohedrons can be described by trigonal crystal lattice structures. Therefore, all cubic lattice constants and crystal planes (hkl) s can be transformed into those of trigonal crystal parameters. These unique alignments enable a new opportunity of perfect lattice matching conditions, which can eliminate misfit dislocations. Previously, these atomic alignments were thought to be impossible or very difficult. With the invention of a new x-ray diffraction measurement method here, growth of cubic semiconductors on trigonal crystals became possible. This epitaxy and lattice-matching condition can be applied not only to SiGe (111)/sapphire (0001) substrate relations, but also to other crystal structures and other materials, including similar crystal structures which have pointgroup rotational symmetries by 120 because the cubic (111) direction has 120 rotational symmetry. The use of slightly miscut (less than

  11. The seed bank of a gallery forest in Southeastern Brazil

    Directory of Open Access Journals (Sweden)

    Maria Tereza Grombone-Guaratini

    2004-09-01

    Full Text Available The soil seed bank was studied in a gallery forest in Southeastern Brazil. Samples were collected from edge to edge along transects perpendicular to the river during the wet (December, 1990 and dry (August, 1991 seasons. The number of seeds found in the seed bank samples was greater in the dry season than in the wet season indicating that there was important variation in the seed stocks in these two periods. The similarity values between the seed bank and the community composition were low. The high density of weed species might be reflecting forest fragmentation and indicating a degree of perturbation.O banco de sementes do solo foi estudado em uma floresta de galeria. As amostras de banco de sementes foram coletadas ao longo de transectos abertos perpendicularmente à área do rio durante as estações chuvosa (dezembro/1990 e seca (agosto/1991. O número de sementes encontrado nas amostras de banco de sementes proveniente da estação seca foi significativamente maior do que o número de sementes encontrado nas amostras provenientes da estação chuvosa. Os resultados obtidos evidenciaram uma variação significativa entre o estoque de sementes encontrados nos dois períodos amostrados. A similaridade entre o estoque de sementes no solo e a flora local foi baixa. A alta densidade de espécies invasoras pode refletir a fragmentação e indicar o grau de perturbação da floresta.

  12. Flashlamp pumped Ti-sapphire laser for ytterbium glass chirped pulse amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akihiko; Ohzu, Akira; Sugiyama, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-03-01

    A flashlamp pumped Ti:sapphire laser is designed for ytterbium glass chirped pulse amplification. A high quality Ti:sapphire rod and a high energy long pulse discharging power supply are key components. The primary step is to produce the output power of 10 J per pulse at 920 nm. (author)

  13. Ti:sapphire rib channel waveguide fabricated by reactive ion etching of a planar waveguide

    NARCIS (Netherlands)

    Crunteanu, A.; Jänchen, G.; Salathé, R.P.; Hoffmann, P.; Pollnau, M.; Eason, R.W.; Shepherd, D.P.

    2002-01-01

    We were successful in creating 1.4-µm high ribs in a Ti:sapphire planar waveguide by reactive ion etching. Optical investigations of the obtained structure showed channel-waveguide fluorescence emission of the Ti:sapphire layer after Ar-ion excitation.

  14. Fiber-laser-pumped Ti:sapphire laser

    CERN Document Server

    Samanta, G K; Devi, Kavita; Ebrahim-Zadeh, M

    2010-01-01

    We report the first experimental demonstration of efficient and high-power operation of a Ti:sapphire laser pumped by a simple, compact, continuous-wave (cw) fiber-laser-based green source. The pump radiation is obtained by direct single-pass second-harmonic-generation (SHG) of a 33-W, cw Yb-fiber laser in 30-mm-long MgO:sPPLT crystal, providing 11 W of single-frequency green power at 532 nm in TEM00 spatial profile with power and frequency stability better than 3.3% and 32 MHz, respectively, over one hour. The Ti:sapphire laser is continuously tunable across 743-970 nm and can deliver an output power up to 2.7 W with a slope efficiency as high as 32.8% under optimum output coupling of 20%. The laser output has a TEM00 spatial profile with M2<1.44 across the tuning range and exhibits a peak-to-peak power fluctuation below 5.1% over 1 hour.

  15. Temperature behavior of damage in sapphire implanted with light ions

    Energy Technology Data Exchange (ETDEWEB)

    Alves, E. [Ion Beam Laboratory, Instituto Tecnologico e Nuclear, Sacavem 2686-953 (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Lisbon (Portugal)], E-mail: ealves@itn.pt; Marques, C. [Ion Beam Laboratory, Instituto Tecnologico e Nuclear, Sacavem 2686-953 (Portugal); Centro de Fisica Nuclear da Universidade de Lisboa, Lisbon (Portugal); Safran, G. [Research Institute for Technical Physics and Materials Science, H-1525 Budapest (Hungary); McHargue, Carl J. [University of Tennessee, Knoxville, TN 37996-0750 (United States)

    2009-05-01

    In this study, we compare and discuss the defect behavior of sapphire single crystals implanted with different fluences (1 x 10{sup 16}-1 x 10{sup 17} cm{sup -2}) of carbon and nitrogen with 150 keV. The implantation temperatures were RT, 500 deg. C and 1000 deg. C to study the influence of temperature on the defect structures. For all the ions the Rutherford backscattering-channeling (RBS-C) results indicate a surface region with low residual disorder in the Al-sublattice. Near the end of range the channeled spectrum almost reaches the random indicating a high damage level for fluences of 1 x 10{sup 17} cm{sup -2}. The transmission electron microscopy (TEM) photographs show a layered contrast feature for the C implanted sample where a buried amorphous region is present. For the N implanted sample the Electron Energy Loss Spectroscopy (EELS) elemental mapping give evidence for the presence of a buried damage layer decorated with bubbles. Samples implanted at high temperatures (500 deg. C and 1000 deg. C) show a strong contrast fluctuation indicating a defective crystalline structure of sapphire.

  16. The effect of crystal orientation on the cryogenic strength of hydroxide catalysis bonded sapphire

    Science.gov (United States)

    Haughian, K.; Douglas, R.; van Veggel, A. A.; Hough, J.; Khalaidovski, A.; Rowan, S.; Suzuki, T.; Yamamoto, K.

    2015-04-01

    Hydroxide catalysis bonding has been used in gravitational wave detectors to precisely and securely join components of quasi-monolithic silica suspensions. Plans to operate future detectors at cryogenic temperatures has created the need for a change in the test mass and suspension material. Mono-crystalline sapphire is one candidate material for use at cryogenic temperatures and is being investigated for use in the KAGRA detector. The crystalline structure of sapphire may influence the properties of the hydroxide catalysis bond formed. Here, results are presented of studies of the potential influence of the crystal orientation of sapphire on the shear strength of the hydroxide catalysis bonds formed between sapphire samples. The strength was tested at approximately 8 K; this is the first measurement of the strength of such bonds between sapphire at such reduced temperatures. Our results suggest that all orientation combinations investigated produce bonds of sufficient strength for use in typical mirror suspension designs, with average strengths >23 MPa.

  17. Electronic structure analysis of GaN films grown on r- and a-plane sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Monu; Krishna TC, Shibin; Aggarwal, Neha [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory (CSIR-NPL), Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Vihari, Saket [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory (CSIR-NPL), Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Gupta, Govind, E-mail: govind@nplindia.org [Physics of Energy Harvesting Division, CSIR-National Physical Laboratory (CSIR-NPL), Dr. K.S. Krishnan Marg, New Delhi 110012 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K.S. Krishnan Marg, New Delhi 110012 (India)

    2015-10-05

    Graphical abstract: Substrate orientation induced changes in surface chemistry, band bending, hybridization states, electronic properties and surface morphology of epitaxially grown GaN were investigated via photoemission spectroscopic and Atomic Force Microscopic measurements. - Highlights: • Electronic structure and surface properties of GaN film grown on r/a-plane sapphire. • Downward band bending (0.5 eV) and high surface oxide is observed for GaN/a-sapphire. • Electron affinity and ionization energy is found to be higher for GaN/a-sapphire. - Abstract: The electronic structure and surface properties of epitaxial GaN films grown on r- and a-plane sapphire substrates were probed via spectroscopic and microscopic measurements. X-ray photoemission spectroscopic (XPS) measurements were performed to analyse the surface chemistry, band bending and valence band hybridization states. It was observed that GaN/a-sapphire display a downward band bending of 0.5 eV and possess higher amount of surface oxide compared to GaN/r-sapphire. The valence band (VB) investigation revealed that the hybridization corresponds to the interactions of Ga 4s and Ga 4p orbitals with N 2p orbital, and result in N2p–Ga4p, N2p–Ga4s{sup ∗}, mixed and N2p–Ga4s states. The energy band structure and electronic properties were measured via ultraviolet photoemission spectroscopic (UPS) experiments. The band structure analysis and electronic properties calculations divulged that the electron affinity and ionization energy of GaN/a-sapphire were 0.3 eV higher than GaN/r-sapphire film. Atomic Force Microscopic (AFM) measurements revealed faceted morphology of GaN/r-sapphire while a smooth pitted surface was observed for GaN/a-sapphire film, which is closely related to surface oxide coverage.

  18. Seasonal feeding ecology of ring-tailed lemurs: a comparison of spiny and gallery forest habitats.

    Science.gov (United States)

    LaFleur, Marni; Sauther, Michelle L

    2015-01-01

    Although Lemur catta persists in many habitat types in southern Madagascar, its ecology has been primarily studied within gallery forests. We compare plant food selection and properties for ring-tailed lemurs in the spiny and gallery forests over the synchronized lactation period (September to March) that includes both the dry and wet seasons. We found no significant habitat-specific differences in the type of plant part consumed per month (i.e. flower, fruit, leaf) or between the intake of soluble carbohydrates. However, the presence and use of Tamarindus indica plants appear to elevate protein and fiber intake in the gallery forest lemurs' diets. Protein is especially important for reproductive females who incur the added metabolic costs associated with lactation; however, fiber can disrupt protein digestion. Future work should continue to investigate how variations of protein and fiber affect ring-tailed lemur dietary choice and nutrient acquisition.

  19. Stress Distribution on Blasting Gallery Barrier Pillar due to Goaf Formation During Extraction

    Science.gov (United States)

    Kumar Reddy, Sandi; Sastry, Vedala Rama

    2016-10-01

    Semi-mechanised blasting gallery mining is a sustainable option to achieve higher production and productivity from underground thick coal seams. Judicious design of underground blasting gallery panel requires understanding of stress distribution on barrier pillars during different stages of extraction. This paper presents a study of stress distribution in and around barrier pillar for the different stages of extraction in the blasting gallery panel. Finite difference analysis taken up for final excavation (depillaring) in the panel with different stages of extraction. Analysis revealed that the stress transferred on barrier pillar increased as progress of excavation increased. Maximum stress was observed at a distance of 10 and 12 m from the pillar edge for virgin and goaved out panel sideby respectively, which gradually decreased towards centre of the pillar.

  20. Experiences from a Real-Time Mobile Collaborative Writing System in an Art Gallery

    DEFF Research Database (Denmark)

    Korn, Matthias; Polli, Anna Maria; Klokmose, Clemens Nylandsted

    We present first experiences from Local Area Artworks, a system enabling collaborative art interpretation on-site, deployed during an exhibition in a local art gallery. Through the system, we explore ways to re-connect people to local places by making use of their personal mobile devices as inter......We present first experiences from Local Area Artworks, a system enabling collaborative art interpretation on-site, deployed during an exhibition in a local art gallery. Through the system, we explore ways to re-connect people to local places by making use of their personal mobile devices...... as interfaces to the shared physical space. With a collocated collaborative writing system in the semi-public space of a gallery, we encourage local art discussions and provide a platform for the public to actively participate in interpretations of individual artworks. In this paper, we focus on the experiences...

  1. Stress Distribution on Blasting Gallery Barrier Pillar due to Goaf Formation During Extraction

    Science.gov (United States)

    Kumar Reddy, Sandi; Sastry, Vedala Rama

    2015-09-01

    Semi-mechanised blasting gallery mining is a sustainable option to achieve higher production and productivity from underground thick coal seams. Judicious design of underground blasting gallery panel requires understanding of stress distribution on barrier pillars during different stages of extraction. This paper presents a study of stress distribution in and around barrier pillar for the different stages of extraction in the blasting gallery panel. Finite difference analysis taken up for final excavation (depillaring) in the panel with different stages of extraction. Analysis revealed that the stress transferred on barrier pillar increased as progress of excavation increased. Maximum stress was observed at a distance of 10 and 12 m from the pillar edge for virgin and goaved out panel sideby respectively, which gradually decreased towards centre of the pillar.

  2. Topological Galleries: A High Level User Interface for Topology Controlled Volume Rendering

    Energy Technology Data Exchange (ETDEWEB)

    MacCarthy, Brian; Carr, Hamish; Weber, Gunther H.

    2011-06-30

    Existing topological interfaces to volume rendering are limited by their reliance on sophisticated knowledge of topology by the user. We extend previous work by describing topological galleries, an interface for novice users that is based on the design galleries approach. We report three contributions: an interface based on hierarchical thumbnail galleries to display the containment relationships between topologically identifiable features, the use of the pruning hierarchy instead of branch decomposition for contour tree simplification, and drag-and-drop transfer function assignment for individual components. Initial results suggest that this approach suffers from limitations due to rapid drop-off of feature size in the pruning hierarchy. We explore these limitations by providing statistics of feature size as function of depth in the pruning hierarchy of the contour tree.

  3. Colloid-borne uranium and other heavy metals in the water of a mine drainage gallery

    Energy Technology Data Exchange (ETDEWEB)

    Zaenker, H.; Richter, W.; Brendler, V.; Nitsche, H. [Forschungszentrum Rossendorf e.V. (FZR) (Germany). Inst. fuer Radiochemie

    2000-07-01

    The water of a mine drainage gallery was investigated for its contents of colloid-borne heavy metals with emphasis on uranium. About 1 mg/L of colloid particles of 100 to 300 nm were found. They consist of a matrix of Fe and Al oxyhydroxides and are formed when anoxic slightly acidic shaft waters mix with oxic near-neutral gallery water. The colloid particles bear toxic trace elements such as As, Pb, and Cu. Almost 100% of the As and Pb and about 70% of the Cu contained in the water are colloid-borne. Carbonato complexes prevent the uranyl from being adsorbed on the colloids in the unaltered gallery water. Acidification destroys these complexes: up to 50% of the uranium is attached to the colloids in the slightly acidic pH region. Further acidification converts the uranyl again to a 'non-colloidal' form. (orig.)

  4. Viability of microcomputed tomography to study tropical marine worm galleries in humid muddy sediments

    Energy Technology Data Exchange (ETDEWEB)

    Pennafirme, Simone F., E-mail: sipennafirme@gmail.com [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Biologia. Dept. de Biologia Marinha; Machado, Alessandra S.; Lima, Inaya; Suzuki, Katia N.; Lopes, Ricardo T., E-mail: machado@lin.ufrj.br, E-mail: inaya@lin.ufrj.br, E-mail: norisuzuki6@yahoo.com.br, E-mail: ricardo@lin.ufj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/UFRJ), RJ (Brazil). Lab. de Instrumentacao Nuclear

    2013-07-01

    Bioturbation is an ecological process driven by organisms, which transports nutrients and gases from air/water to sediment through their galleries, by the time they feed, burrow and/or construct galleries. This exchange is vital to the maintenance of micro and macrobenthic organisms, mainly in muddy flat environments. Species with distinct galleries could create levels of bioturbation, affecting the benthic interactions. In this sense, it is fundamental developing a non-destructive method that permits identifying/quantifying the properties of these galleries. The recent advances in micro-computed tomography are allowing the high resolution 3D images generation. However, once muddy sediments are rich in organic matter and interstitial water, these would lead to motion artifacts which could, in turn, decrease the accuracy of galleries identification/quantification. In this context, the aim of this study was to develop a protocol which combines laboratory experiments and microtomography analysis in order to generate accurate 3D images of the small marine worm's galleries within humid muddy sediments. The sediment was collected at both muddy flats of Surui's and Itaipu lagoon's mangroves (RJ-Brazil), sieved (0.5mm mesh) and introduced with one individual of the marine worm Laeonereis acuta (Nereididae, Polychaeta) in each acrylic corer holders (4.4cm of internal diameter). High energy microtomography scanner was used to obtain 3D images and the setup calibration was 130 kV and 61 mA. Each acquisition image time was among 4h and 6h. Several procedures of drying remained water inside the cores were performed aiming obtaining images without movement artifacts due to circulating water, and this issue was one of the main studied parameter. In order to investigate possible chemical effects, 2ml of formalin (35%) with menthol were added to the surface of the cores. The results show that although the drying time was appropriated, the chemicals created bubbles

  5. High-temperature sapphire optical sensor fiber coatings

    Science.gov (United States)

    Desu, Seshu B.; Claus, Richard O.; Raheem, Ruby; Murphy, Kent A.

    1990-10-01

    the filter. These modes may be attributed to a number of material degradation mechanisms, such as thermal shock, oxidation corrosion of the material, mechanical loads, or phase changes in the filter material. Development of high temperature optical fiber (sapphire) sensors embedded in the CXF filters would be very valuable for both monitoring the integrity of the filter during its use and understanding the mechanisms of degradation such that durable filter development will be facilitated. Since the filter operating environment is very harsh, the high temperature sapphire optical fibers need to be protected and for some sensing techniques the fiber must also be coated with low refractive index film (cladding). The objective of the present study is to identify materials and develop process technologies for the application of claddings and protective coatings that are stable and compatible with sapphire fibers at both high temperatures and pressures.

  6. Superexciplex of Coumarin Molecules using Tunable Ti-Sapphire Laser

    Science.gov (United States)

    Al-Ghamdi, Attieh Ali; Al-Dwayyan, Abdullah S.; Masilamani, Vadivel; Al-Saud, Turki Saud M.; Al-Salhi, Mohammed Saleh

    2003-10-01

    Certain highly polar dye molecules exhibit an additional optical gain band under pulsed laser excitation, while there is no such band under steady-state continuous wave (CW) lamp excitation. This new band is not due to an excimer, an exciplex or a two-photon fluorescence band but stems from the formation of a new molecular complex in which two excited molecules remain associated with a solvent molecule acting as a bridge. In this paper, the characteristics of superexciplexes of four related coumarin molecules are presented. All molecules were excited using a tunable Ti-sapphire laser pulse 10 ns in width. The distinct difference between the amplified spontaneous emission (ASE) spectra obtained with tunable laser and tunable lamp excitation demonstrated that twisted intramolecular charge transfer (TICT) conformations might also assist in the formation of these superexciplexes.

  7. The charge state of iron implanted into sapphire

    Energy Technology Data Exchange (ETDEWEB)

    McHargue, C.J.; Sklad, P.S.; White, C.W.; Farlow, G.C.; Perez, A.; Kornilios, N.; Marest, G.

    1987-08-01

    Several techniques (RBS, TEM, CEMS) have been used to characterize sapphire single crystals implanted with iron at room temperature to fluences of 10/sup 16/ to 10/sup 17/ ions cm/sup -2/. At low fluences the as-implanted iron is found mainly in the ferrous state. As the fluence is increased, Fe/sup 3 +/ and metallic iron clusters became dominant. There is a strong correlation between the probability of finding specific configurations of iron ions within four cation coordination shells and the relative amounts of each charge state observed. The superparamagnetic behavior of the clusters suggest that they are of the order of 2 nm in size but the large amount of irradiation-induced damage and residual stress has prevented their imaging by TEM. 13 refs., 7 figs.

  8. Numerical computation of sapphire crystal growth using heat exchanger method

    Science.gov (United States)

    Lu, Chung-Wei; Chen, Jyh-Chen

    2001-05-01

    The finite element software FIDAP is employed to study the temperature and velocity distribution and the interface shape during a large sapphire crystal growth process using a heat exchanger method (HEM). In the present study, the energy input to the crucible by the radiation and convection inside the furnace and the energy output through the heat exchanger is modeled by the convection boundary conditions. The effects of the various growth parameters are studied. It is found that the contact angle is obtuse before the solid-melt interface touches the sidewall of the crucible. Therefore, hot spots always appear in this process. The maximum convexity decreases significantly when the cooling-zone radius (RC) increases. The maximum convexity also decreases significantly as the combined convection coefficient inside the furnace (hI) decreases.

  9. Adapting a Cryogenic Sapphire Oscillator for Very Long Baseline Interferometry

    CERN Document Server

    Doeleman, Sheperd; Rogers, Alan; Hartnett, John; Tobar, Michael; Nand, Nitin; 10.1086/660156

    2011-01-01

    Extension of very long baseline interferometry (VLBI) to observing wavelengths shorter than 1.3mm provides exceptional angular resolution (~20 micro arcsec) and access to new spectral regimes for the study of astrophysical phenomena. To maintain phase coherence across a global VLBI array at these wavelengths requires that ultrastable frequency references be used for the heterodyne receivers at all participating telescopes. Hydrogen masers have traditionally been used as VLBI references, but atmospheric turbulence typically limits (sub) millimeter VLBI coherence times to ~1-30 s. Cryogenic Sapphire Oscillators (CSO) have better stability than Hydrogen masers on these time scale and are potential alternatives to masers as VLBI references. Here, We describe the design, implementation and tests of a system to produce a 10 MHz VLBI frequency standard from the microwave (11.2 GHz) output of a CSO. To improve long-term stability of the new reference, the CSO was locked to the timing signal from the Global Positionin...

  10. Analysis and modification of blue sapphires from Rwanda by ion beam techniques

    Energy Technology Data Exchange (ETDEWEB)

    Bootkul, D., E-mail: mo_duangkhae@hotmail.com [Department of General Science - Gems & Jewelry, Faculty of Science, Srinakharinwirot University, Bangkok 10110 (Thailand); Chaiwai, C.; Tippawan, U. [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wanthanachaisaeng, B. [Gems Enhancement Research Unit, Faculty of Gems, Burapha University, Chanthaburi Campus, Chanthaburi 22170 (Thailand); Intarasiri, S., E-mail: saweat@gmail.com [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2015-12-15

    Highlights: • Ion beam analysis is an effective method for detecting trace elements. • Ion beam treatment is able to improve optical and color appearances of the blue sapphire from Rwanda. • These alternative methods can be extended to jewelry industry for large scale application. - Abstract: Blue sapphire is categorised in a corundum (Al{sub 2}O{sub 3}) group. The gems of this group are always amazed by their beauties and thus having high value. In this study, blue sapphires from Rwanda, recently came to Thai gemstone industry, are chosen for investigations. On one hand, we have applied Particle Induced X-ray Emission (PIXE), which is a highly sensitive and precise analytical technique that can be used to identify and quantify trace elements, for chemical analysis of the sapphires. Here we have found that the major element of blue sapphires from Rwanda is Al with trace elements such as Fe, Ti, Cr, Ga and Mg as are commonly found in normal blue sapphire. On the other hand, we have applied low and medium ion implantations for color improvement of the sapphire. It seems that a high amount of energy transferring during cascade collisions have altered the gems properties. We have clearly seen that the blue color of the sapphires have been intensified after nitrogen ion bombardment. In addition, the gems were also having more transparent and luster. The UV–Vis–NIR measurement detected the modification of their absorption properties, implying of the blue color increasing. Here the mechanism of these modifications is postulated and reported. In any point of view, the bombardment by using nitrogen ion beam is a promising technique for quality improvement of the blue sapphire from Rwanda.

  11. Chinese Whispers

    Science.gov (United States)

    Kirkby, Mike

    2016-04-01

    In discrete networks, disconnection is often the critical factor that controls system function. The quality of network behaviour may be described by graph-theoretic indices such as the Cheeger constant, or through context-specific models. For water and sediment transport, one primary distinction is between unchannelled and channelled flow: diffusive sediment transport in the former providing poor connectivity and the progressive dominance of advective processes leading to better connected channelization. Within the channel network, Fryir's terminology of buffers, barriers and blankets describe types of disconnection that control water and sediment movement which are crucial to, for example, flood management. In the long term and at coarse scales, network connectivity is controlled by disconnection across divides and through sea level change. Willett has proposed a network analysis that shows catchments whose headwaters are threatened by capture and distributions of fish have provided evidence of the efficacy and rate of these processes, in Africa and elsewhere. Is there common ground between these approaches that can be applied to modelling the behaviour of social and other networks? The critical role of poor connections seems to be at least one significant common thread.

  12. Whispering wind

    DEFF Research Database (Denmark)

    Barlieb, Christophe; Richter, Christoph; Greschner, Björn

    2009-01-01

    Low frequency noise generated by aircraft during pre-takeoff, takeoff, landing and post-landing operations equates to high levels of undesirable ground noise pollution. This phenomenon is gaining heightened popular interest among air transportation specialists and agencies as urban settlements an...

  13. Large-scale inhomogeneity in sapphire test masses revealed by Rayleigh scattering imaging

    Science.gov (United States)

    Yan, Zewu; Ju, Li; Eon, François; Gras, Slawomir; Zhao, Chunnong; Jacob, John; Blair, David G.

    2004-03-01

    Rayleigh scattering in test masses can introduce noise and reduce the sensitivity of laser interferometric gravitational wave detectors. In this paper, we present laser Rayleigh scattering imaging as a technique to investigate sapphire test masses. The system provides three-dimensional Rayleigh scattering mapping of entire test masses and quantitative evaluation of the Rayleigh scattering coefficient. Rayleigh scattering mapping of two sapphire samples reveals point defects as well as inhomogeneous structures in the samples. We present results showing significant non-uniform scattering within two 4.5 kg sapphire test masses manufactured by the heat exchanger method.

  14. Experiences from a Real-Time Mobile Collaborative Writing System in an Art Gallery

    DEFF Research Database (Denmark)

    Korn, Matthias; Polli, Anna Maria; Klokmose, Clemens Nylandsted

    We present first experiences from Local Area Artworks, a system enabling collaborative art interpretation on-site, deployed during an exhibition in a local art gallery. Through the system, we explore ways to re-connect people to local places by making use of their personal mobile devices...

  15. Durability of visitable concrete sewer gallery under the effect of domestic wastewater

    Science.gov (United States)

    Salhi, Aimed; Kriker, Abdelouahed; Tioua, Tahar; Abimiloud, Youcef; Barluenga, Gonzalo

    2016-07-01

    The durability of concrete structures for the disposal of wastewater depends on their behavior when faced to different aggressions such as mechanics, chemical and biological, causing a deterioration often cementing matrix. The deterioration of recent evacuations wastewater infrastructure, made of reinforced concrete less than 15 years ago, has become an important concern. The aim of this study was to investigate the degradation and the factors responsible for the deterioration of the concrete visitable gallery of sewage from the town of Touggourt (south-east of Algeria). Thus, samples from different parts of the gallery were extracted and unaltered samples were selected as a reference. A degraded sample exposed to H2S gas and another sample of the gallery submerged into wastewater were analyzed to characterize the internal and external damage to the gallery as well as the chemical and mineralogical changes. These tests were complemented by a physical and mechanical characterization of the samples. The experimental results showed the strong anisotropy of both internal and external damage.

  16. Fra Bartolomeo della Porta detto Fra Bartolomeo, Adorazione del Bambino, National Gallery, London

    DEFF Research Database (Denmark)

    Fischer, Chris

    2014-01-01

    En artikel om et maleri af Fra Bartolomeo i National Gallery i London udlånt til en udstilling i Museo Tosio Martinengo I Brescia i forbindelse med opdagelsen af et fuldstændigt overensstemmende maleri i dette museums magasiner. Hypotesen var at Bresciabilledet var et værkstedsarbejde lavet på...

  17. Bringing Image and Language Together: A Workshop at the Lehman College Art Gallery.

    Science.gov (United States)

    Wexler, Alice

    2001-01-01

    Discusses a ten day workshop for kindergarten and fourth grade students that centered around the art exhibit "Contemporary Chinese Art and the Literary Culture of China" held at the Lehman College Art Gallery (Bronx, New York). Explains that students created accordion books based on Xing Fei's "Red Book." (CMK)

  18. Rupestral painting in the superior gallery of Altxerri cave (Aia, Gipuzkoa

    Directory of Open Access Journals (Sweden)

    Jesús ALTUNA

    2010-07-01

    Full Text Available We describe new details of a complex figure made with red paint in a superior gallery of Altxerri cave. The head of a bison with a corniform motif stands out among other strokes of difficult interpretation. This collection of paintings has no correlation with the numerous engravings and black paintings of the main gallery of this cave. There is no access to this superior gallery from the main gallery of the cave so the Paleolithic artist would have gained access through another entry from the mountain that is unknown in the present. Near the collection of paintings described there is a bison vertebra stuck by its spinous apophysis in a crack on the rock. The C14 dating of the vertebra has not been possible due to the lack of collagen in the sample. Underneath this figure, tarsal remains of two individuals of Rupicapra rupicapra were found dated 34195 ± 1235 y 29940 ± 745 BP. The contemporaneity of the remains and the figure cannot be established.

  19. Bringing Image and Language Together: A Workshop at the Lehman College Art Gallery.

    Science.gov (United States)

    Wexler, Alice

    2001-01-01

    Discusses a ten day workshop for kindergarten and fourth grade students that centered around the art exhibit "Contemporary Chinese Art and the Literary Culture of China" held at the Lehman College Art Gallery (Bronx, New York). Explains that students created accordion books based on Xing Fei's "Red Book." (CMK)

  20. The Spiral Gallery: Non-Market Creativity and Belonging in an Australian Country Town

    Science.gov (United States)

    Waitt, Gordon; Gibson, Chris

    2013-01-01

    This paper seeks to explore creative practice in an Australian country town, and in so doing, to unsettle market-orientated interpretations of creativity that privilege the urban. Instead of focusing on creative practice as a means to develop industries, we focus on how creativity is a means to establish a cooperative gallery space that helps to…

  1. The Artist-Led Pedagogic Process in the Contemporary Art Gallery: Developing a Meaning Making Framework

    Science.gov (United States)

    Pringle, Emily

    2009-01-01

    Drawing on recent research which examined how selected artist educators perceive themselves as arts practitioners and analysed how these constructions inform their pedagogy, this article proposes a framework of meaning making in the art gallery. Art practice is defined as a process of conceptual and experiential enquiry which embraces inspiration,…

  2. Lifelong Learning for People Aged 64+ within the Contemporary Art Gallery Context

    Science.gov (United States)

    Goulding, Anna

    2012-01-01

    This paper reports the initial findings from Contemporary Visual Art and Identity Construction--Wellbeing Amongst Older People: a two-year research project that aims to understand how the lives of older people can be improved by examining their use of contemporary visual art in the art gallery and museum. It will focus on data relating to lifelong…

  3. Identification of natural plasma emissions observed close to the plasmapause by the Cluster-Whisper relaxation sounder

    Directory of Open Access Journals (Sweden)

    P. Canu

    Full Text Available We use the data collected by the Whisper instrument onboard the Cluster spacecraft for a first test of its capabilities in the identification of the natural plasma waves observed in the Earth’s magnetosphere. The main signatures observed at the plasma frequency, upper hybrid frequency, and electron Bernstein modes were often difficult to be reliably recognized on previous missions. We use here the characteristic frequencies provided by the resonances triggered by the relaxation sounder of Whisper to identify with good confidence the various signatures detected in the complex wave spectra collected close to the plasmapause. Coupled with the good sensitivity, frequency and time resolution of Whisper, the resonances detected by the sounder allow one to precisely spot these natural emissions. This first analysis seems to confirm the interpretation of Geos observations: the natural emissions observed in Bernstein modes above the plasma frequency, now widely observed onboard Cluster, are not modeled by a single Maxwellian electrons distribution function. Therefore, multi-temperature electron distribution functions should be considered.

    Key words. Space plasma physics (active perturbation experiments; waves and instabilities; instrument and techniques

  4. Frequency-doubled diode laser for direct pumping of Ti:sapphire lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika

    2012-01-01

    A single-pass frequency doubled high-power tapered diode laser emitting nearly 1.3 W of green light suitable for direct pumping of Ti:sapphire lasers generating ultrashort pulses is demonstrated. The pump efficiencies reached 75 % of the values achieved with a commercial solid-state pump laser....... However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20...... fs are measured. These results open the opportunity of establishing diode laser pumped Ti:sapphire lasers for e.g. biophotonic applications like retinal optical coherence tomography or pumping of photonic crystal fibers for CARS microscopy....

  5. MBE growth and characterization of ZnTe epilayers on m-plane sapphire substrates

    Energy Technology Data Exchange (ETDEWEB)

    Nakasu, Taizo; Sun, Wei-Che; Yamashita, Sotaro; Aiba, Takayuki; Taguri, Kosuke [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo 169-8555 (Japan); Kobayashi, Masakazu [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo 169-8555 (Japan); Kagami Memorial Research Institute for Materials Science and Technology, Waseda University, 2-8-26, Tokyo 169-0051 (Japan); Asahi, Toshiaki [Technology Development Center, JX Nippon Mining and Metals Corporation, Hitachi 317-0056 (Japan); Togo, Hiroyoshi [NTT Microsystem Integration Laboratories, Atsugi 243-0198 (Japan)

    2014-07-15

    ZnTe epilayers were grown on transparent (10-10) oriented (m -plane) sapphire substrates by molecular beam epitaxy (MBE). Pole figure imaging was used to study the domain distribution within the layer. (211)-oriented ZnTe domains were formed on m -plane sapphire. The presence of only one kind of (211) ZnTe domain formed on the 2 -tilted m -plane sapphire substrates was confirmed. Thus, single domain (211) ZnTe epilayers can be grown on the m -plane sapphire using MBE. Although differences in the crystal structure and lattice mismatch are large, precise control of the substrate surface lattice arrangement result in the formation of high-quality epitaxial layers. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Annealing effects of sapphire substrate on properties of ZnO films grown by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.Z. [South China Normal University, School of Physics and Telecommunication Engineering, Guangzhou (China); Xu, J. [Chinese Academy of Sciences, Shanghai Institute of Optics and Fine Mechanics, P.O. Box 800-211, Shanghai (China)

    2007-09-15

    The annealing effects of sapphire substrates on the quality of epitaxial ZnO films grown by dc reactive magnetron sputtering were studied. The atomic steps formed on (0001) sapphire ({alpha}-Al{sub 2}O{sub 3}) substrates surface by annealing at high temperature were analyzed by atomic force microscopy. Their influence on the growth of ZnO films was examined by X-ray diffraction and photoluminescence measurements. Experimental results indicate that the film quality is strongly affected by annealing treatment of the sapphire substrate surface. The optimum annealing temperature of sapphire substrates for ZnO grown by magnetron sputtering is 1400 C for 1 h in air. (orig.)

  7. Dislocation Analysis for Large-sized Sapphire Single Crystal Grown by SAPMAC Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, large-sized sapphire (Φ230×210 mm, 27.5 kg) was grown by SAPMAC method (sapphire growth technique with micro-pulling and shoulder-expanding at the cooled center). Dislocation peculiarity in large sapphire boule (0001) basal plane was investigated by chemical etching, scanning electron microscopy and X-ray topography method. The triangular dislocation etch pit measured is 7.6×101~8.0×102 cm-2, in which relative high-density dislocations were generated at both initial and final stages of crystal growth. The analysis of single-crystal X-ray topography shows that there are no apparent sub-grain boundaries; the dislocation lines are isolated and straight. Finally, the origins of low-density dislocation in sapphire crystal are discussed by numerical analysis method.

  8. Advances in Trace Element "Fingerprinting" of Gem Corundum, Ruby and Sapphire, Mogok Area, Myanmar

    National Research Council Canada - National Science Library

    F Lin Sutherland; Khin Zaw; Sebastien Meffre; Tzen-Fui Yui; Kyaw Thu

    2015-01-01

    ... corundum area and also identified rare alluvial ruby and sapphire grains characterised by unusually high silicon, calcium and gallium, presence of noticeable boron, tin and niobium and very low iron, titanium and magnesium contents...

  9. Newly designed multilayer thin film mirror for dispersion compensation in Ti: sapphire femtosecond lasers

    Institute of Scientific and Technical Information of China (English)

    Chunyan Liao; Jianda Shao; Jianbing Huang; Zhengxiu Fan; Hongbo He

    2005-01-01

    @@ There are two different effects to generate group delay dispersion by multilayer thin film mirrors: chirper effect and Gires-Tournois effect. Both effects are employed to introduce desired dispersion in the designed mirror. Thus the designed mirror provides large dispersion throughout broad waveband. Such mirror can be used for dispersion compensation in Ti:sapphire femtosecond lasers. Most group delay dispersion of a 5-mm Ti:sapphire crystal can be compensated perfectly with only four bounces of the designed mirror.

  10. Growth of crystalline ZnO films on the nitridated (0001) sapphire surface

    Energy Technology Data Exchange (ETDEWEB)

    Butashin, A. V.; Kanevsky, V. M.; Muslimov, A. E., E-mail: amuslimov@mail.ru; Prosekov, P. A.; Kondratev, O. A.; Blagov, A. E.; Vasil’ev, A. L.; Rakova, E. V. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Babaev, V. A.; Ismailov, A. M. [Dagestan State University (Russian Federation); Vovk, E. A.; Nizhankovsky, S. V. [National Academy of Sciences of Ukraine, Institute for Single Crystals (Ukraine)

    2015-07-15

    The surface morphology and structure of (0001) sapphire substrates subjected to thermochemical nitridation in a mixture of N{sub 2}, CO, and H{sub 2} gases are investigated by electron and probe microscopy and X-ray and electron diffraction. It is shown that an aluminum nitride layer is formed on the substrate surface and heteroepitaxial ZnO films deposited onto such substrates by magnetron sputtering have a higher quality when compared with films grown on sapphire.

  11. Determining residual impurities in sapphire by means of electron paramagnetic resonance and nuclear activation analysis

    Science.gov (United States)

    Bletskan, D. I.; Bratus', V. Ya.; Luk'yanchuk, A. R.; Maslyuk, V. T.; Parlag, O. A.

    2008-07-01

    Sapphire (α-Al2O3) single crystals grown using the Verneuil and Kyropoulos methods have been analyzed using electron paramagnetic resonance and γ-ray spectroscopy with 12-MeV bremsstrahlung excitation. It is established that uncontrolled impurities in the final sapphire single crystals grown by the Kyropoulos method in molybdenum-tungsten crucibles are supplied both from the initial materials and from the furnace and crucible materials

  12. Jones calculus modeling and analysis of the thermal distortion in a Ti:sapphire laser amplifier.

    Science.gov (United States)

    Cho, Seryeyohan; Jeong, Jihoon; Yu, Tae Jun

    2016-06-27

    The mathematical modeling of an anisotropic Ti:sapphire crystal with a significant thermal load is performed. The model is expressed by the differential Jones matrix. A thermally induced distortion in the chirped-pulse amplification process is shown by the solution of the differential Jones matrix. Using this model, the thermally distorted spatio-temporal laser beam shape is calculated for a high-power and high-repetition-rate Ti:sapphire amplifier.

  13. High power all-solid-state quasi-continuous-wave tunable Ti: sapphire laser system

    Institute of Scientific and Technical Information of China (English)

    Lei Zou; Xin Ding; Yue Zou; Hongmei Ma; Wuqi Wen; Peng Wang; Jianquan Yao

    2005-01-01

    This paper reports a high power, all-solid-state, quasi-continuous-wave tunable Ti:sapphire laser system pumped by laser diode (LD) pumped frequency-doubled Nd:YAG laser. The maximum tuned output power of 4.2 W (797 nm) and tuned average power of 3.7 W were achieved when fixing the Ti:sapphire broadband output power at 5.0 W and applying 750-850 nm broadband coated mirror.

  14. Aleutian disease of mink: the antibody response of sapphire and pastel mink to Aleutian disease virus.

    Science.gov (United States)

    Bloom, M E; Race, R E; Hadlow, W J; Chesebro, B

    1975-10-01

    The specific antiviral antibody response of sapphire and pastel mink to Pullman strain of ADV has been examined. Sapphire mink inoculated with from 300,000-3 LD50 developed high levels of specific antibody and AD. Pastel mink inoculated with parallel doses of ADV also produced antibody but did not develop AD. The low incidence of AD in pastel mink inoculated with Pullman strain of ADV is probably related to factors other than antiviral antibody.

  15. Interface defects in GaN/sapphire studied using Rutherford backscattering spectroscopy and channeling

    Indian Academy of Sciences (India)

    S K Sinha; P K Barhai

    2004-06-01

    GaN on sapphire was grown by MOCVD technique. Rutherford backscattering spectra together with channeling along [0 0 0 1] axis were recorded to study the defects at the interface. Detailed calculation shows that the defects at GaN/sapphire interface are due to dislocations which are distributed into the whole thickness of the film and are mainly aligned on the growth direction.

  16. Supersmooth and modified surface of sapphire crystals: Formation, characterization, and applications in nanotechnologies

    Science.gov (United States)

    Muslimov, A. E.; Asadchikov, V. E.; Butashin, A. V.; Vlasov, V. P.; Deryabin, A. N.; Roshchin, B. S.; Sulyanov, S. N.; Kanevsky, V. M.

    2016-09-01

    The results of studying the state of the surface of sapphire crystals by a complex of methods in different stages of crystal treatment are considered by an example of preparing sapphire substrates with a supersmooth surface. The possibility of purposefully forming regular micro- and nanoreliefs and thin transition layers using thermal and thermochemical impacts are considered. The advantages of sapphire substrates with a modified surface for forming heteroepitaxial CdTe and ZnO semiconductor films and ordered ensembles of gold nanoparticles are described. The results of the experiments on the application of crystalline sapphire as a material for X-ray optical elements are reported. These elements include total external reflection mirrors and substrates for multilayer mirrors, output windows for synchrotron radiation, and monochromators working in the reflection geometry in X-ray spectrometers. In the latter case, the problems of the defect structure of bulk crystals sapphire and the choice of a method for growing sapphire crystals of the highest structural quality are considered.

  17. Structural and electronic characterization of graphene grown by chemical vapor deposition and transferred onto sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Joucken, Frédéric, E-mail: frederic.joucken@unamur.be; Colomer, Jean-François; Sporken, Robert; Reckinger, Nicolas

    2016-08-15

    Highlights: • CVD graphene is transferred onto sapphire. • Transport measurements reveal relatively low charge carriers mobility. • Scanning probe microscopy experiments reveal the presence of robust contaminant layers between the graphene and the sapphire, responsible for the low carriers mobility. - Abstract: We present a combination of magnetotransport and local probe measurements on graphene grown by chemical vapor deposition on copper foil and subsequently transferred onto a sapphire substrate. A rather strong p-doping is observed (∼9 × 10{sup 12} cm{sup −2}) together with quite low carrier mobility (∼1350 cm{sup 2}/V s). Atomic force and tunneling imaging performed on the transport devices reveals the presence of contaminants between sapphire and graphene, explaining the limited performance of our devices. The transferred graphene displays ridges similar to those observed whilst graphene is still on the copper foil. We show that, on sapphire, these ridges are made of different thicknesses of the contamination layer and that, contrary to what was reported for hBN or certain transition metal dichalcogenides, no self-cleansing process of the sapphire substrate is observed.

  18. Cellular and humoral antibody responses of normal pastel and sapphire mink to goat erythrocytes.

    Science.gov (United States)

    Lodmell, D L; Bergman, R K; Hadlow, W J; Munoz, J J

    1971-02-01

    This study was undertaken to determine whether normal sapphire and royal pastel mink differ immunologically at the cellular and humoral levels. Two days after primary intraperitoneal (ip) inoculation of goat erythrocytes (GE), essentially no 19 or 7S plaque-forming cells (PFC) per 10(6) cells were detected in spleen or in abdominal and peripheral lymph nodes of either color phase. On the 4th day, more 19S PFC were detected in pastel than in sapphire tissues; pastel tissues also contained 7S PFC, whereas essentially none was present in sapphires until the 6th day. After an ip booster inoculation, the number of PFC was markedly different between the two color phases. These differences were most apparent in spleen and peripheral lymph nodes. In parallel with differences observed in PFC responses between the color phases, total hemolysin and 2-mercaptoethanol-resistant hemolysin titers of pastels exceeded those of sapphires in all but one interval after the primary, and at every interval after the booster, inoculation. These data indicate that sapphire mink are not immunological cripples, nor are they immunologically hyperactive, but that differences do exist between sapphire and royal pastel mink, especially in the response to booster injections of GE.

  19. Laser surface and subsurface modification of sapphire using femtosecond pulses

    Energy Technology Data Exchange (ETDEWEB)

    Eberle, G., E-mail: eberle@iwf.mavt.ethz.ch [Institute of Machine Tools and Manufacturing, ETH Zurich, Leonhardstrasse 21, 8092 Zurich (Switzerland); Schmidt, M. [Chair of Photonic Technologies, University of Erlangen-Nuremberg, Konrad-Zuse-Strasse 3-5, 91052 Erlangen (Germany); Pude, F. [Inspire AG, Technoparkstrasse 1, 8005 Zurich (Switzerland); Wegener, K. [Institute of Machine Tools and Manufacturing, ETH Zurich, Leonhardstrasse 21, 8092 Zurich (Switzerland); Inspire AG, Technoparkstrasse 1, 8005 Zurich (Switzerland)

    2016-08-15

    Highlights: • Single and multipulse ablation threshold of aluminium oxide is determined. • Laser ablation, and in-volume modification followed by wet etching are demonstrated. • Quality following laser processing and laser-material interactions are studied. - Abstract: Two methods to process sapphire using femtosecond laser pulses are demonstrated, namely ablation (surface), and in-volume laser modification followed by wet etching (subsurface). Firstly, the single and multipulse ablation threshold is determined and compared with previous literature results. A unique application of ablation is demonstrated by modifying the entrance aperture of water jet orifices. Laser ablation exhibits advantages in terms of geometric flexibility and resolution, however, defects in the form of edge outbreaks and poor surface quality are evident. Secondly, the role of material transformation, polarisation state and formation of multi-focus structures after in-volume laser modification is investigated in order to explain their influence during the wet etching process. Laser scanning and electron microscopy as well as electron backscatter diffraction measurements supported by ion beam polishing are used to better understand quality and laser-material interactions of the two demonstrated methods of processing.

  20. Local dielectric permittivity profiles of sapphire/polypropylene interfaces

    Science.gov (United States)

    Yu, Liping; Ranjan, V.; Buongiorno Nardelli, M.; Bernholc, J.

    2009-03-01

    Recently, the need for high-power-density capacitors has stimulated research to develop composite dielectric materials with high-k nanoparticles embedded in a polymer matrix. In these materials, surfaces and interfaces may play an important role in determining the overall dielectric properties. We present first-principles investigations of the dielectric permittivity profiles across slabs and interfaces of sapphire(α-Al2O3)/isotactic-polypropylene(iPP). Our results indicate that the permittivity profile at interface strongly depends on the nanoscale averaging procedure. We propose an averaging model that ensures near-locality of the dielectric function. We find that: (i) the dielectric permittivity approaches the corresponding bulk value just a few atomic layers away from the interface or surface; (ii) the dielectric constant is enhanced at the surfaces of the isolated α-Al2O3 slabs, while no enhancement is observed at the iPP slab surfaces; and (iii) the dielectric transition at the αAl2O3/iPP is mainly confined in the αAl2O3 side.

  1. Q-Switching the Flash Ti: Sapphire Laser

    Energy Technology Data Exchange (ETDEWEB)

    Cone, Kelly

    2003-09-05

    The Stanford Linear Accelerator Center (SLAC) uses a flash lamp pumped Ti:Sapphire laser to generate the electron beam inside of the Linac. This laser system was installed at the SLAC Polarized Light Source in 1993. During the past, the system has been upgraded in several steps (eg. installation of Rhodium coated reflectors, cavity redesign, and remote controlled wavelength tunability). Q-switching the laser cavity to increase the peak pulse energy was successfully investigated and further improves the capabilities of the laser system for future polarized beam experiments. Two Pockels cells were used to perform the Q-switch and various diagnostics were used to characterize the modified laser pulse. The timing in relation to the laser trigger, pulse width, and pulse shape applied to the Q-switching Pockels cells (PC) were optimized. No damage to the laser cavity or optical elements occurred. At optimal conditions of Q-switching, the pulse energy of the laser increased from 0.4 mJ to over 3 mJ in a 300 ns pulse. The Q-switched pulse energy can be further increased by extending the hold-off pulse applied to the PC. The laser pulse produced by the Q-switch was long enough (full width half maximum (FWHM) > 200 ns) for pulse shaping and demonstrated good intensity stability (< 0.5% jitter). The increase in output power suggests that Q-switching will be used for future accelerator projects.

  2. Nest-Gallery Development and Caste Composition of Isolated Foraging Groups of the Drywood Termite, Incisitermes minor (Isoptera: Kalotermitidae

    Directory of Open Access Journals (Sweden)

    S. Khoirul Himmi

    2016-07-01

    Full Text Available An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives.

  3. Nest-Gallery Development and Caste Composition of Isolated Foraging Groups of the Drywood Termite, Incisitermes minor (Isoptera: Kalotermitidae).

    Science.gov (United States)

    Himmi, S Khoirul; Yoshimura, Tsuyoshi; Yanase, Yoshiyuki; Oya, Masao; Torigoe, Toshiyuki; Akada, Masanori; Imadzu, Setsuo

    2016-07-22

    An X-ray computed-tomographic examination of nest-gallery development from timbers naturally infested by foraging groups of Incisitermes minor colonies was conducted. This study documents the colonization process of I. minor to new timbers and how the isolated groups maintain their nest-gallery system. The results suggested that development of a nest-gallery within a suitable wood item is not random, but shows selection for softer substrate and other adaptations to the different timber environments. Stigmergic coordinations were expressed in dynamic changes of the nest-gallery system; indicated by fortification behavior in sealing and re-opening a tunnel approaching the outer edge of the timber, and accumulating fecal pellets in particular chambers located beneath the timber surface. The study also examines the caste composition of isolated groups to discover how I. minor sustains colonies with and without primary reproductives.

  4. Origin of Difference in Photocatalytic Activity of ZnO (002 Grown on a- and c-Face Sapphire

    Directory of Open Access Journals (Sweden)

    Guoqiang Li

    2014-01-01

    Full Text Available The oriented (002 ZnO films were grown on a- and c-face sapphire by pulsed laser deposition. The X-ray diffraction analysis revealed that the oriented (002 ZnO films were epitaxially grown on the substrate successfully. The sample on a-face sapphire had higher crystal quality. However, the photocatalytic activity for Rhodamine B degradation of ZnO film on c-face sapphire was higher than that on a-face sapphire. The Raman spectrum and XPS analysis suggested that the sample on a-face sapphire had higher concentration of defects. The result of the contact angle measurement revealed that the sample on c-face sapphire had higher surface energy. And the investigation of the surface conductance implied that the higher light conductance was helpful for the photocatalytic activity.

  5. Effects of sapphire substrates surface treatment on the ZnO thin films grown by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yinzhen [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)], E-mail: agwyz@yahoo.com.cn; Chu Benli [School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou 510631 (China)

    2008-06-01

    The surface treatment effects of sapphire substrate on the ZnO thin films grown by magnetron sputtering were studied. The sapphire substrates properties have been investigated by means of atomic force microscopy (AFM) and X-ray diffraction rocking curves (XRCs). The results show that sapphire substrate surfaces have the best quality by CMP with subsequent chemical etching. The surface treatment effects of sapphire substrate on the ZnO thin films were examined by X-ray diffraction (XRD) and photoluminescence (PL) measurements. Results show that the intensity of (0 0 2) diffraction peak of ZnO thin films on sapphire substrates treated by CMP with subsequent chemical etching was strongest, FWHM of (0 0 2) diffraction peak is the narrowest and the intensity of UV peak of PL spectrum is strongest, indicating surface treatment on sapphire substrate preparation may improve ZnO thin films crystal quality and photoluminescent property.

  6. Sala do Artista Popular: Tradição, Identidade e Mercado / Gallery of the Popular Artist: tradition, identity, market

    OpenAIRE

    Luiz César dos Santos Baía

    2009-01-01

    BAIA, Luiz César dos Santos. Sala do Artista Popular: Tradição, Identidade e Mercado. 2008. Dissertação (Mestrado) – Programa de Pós-Graduação em Museologia e Patrimônio, UNIRIO/MAST, Rio de Janeiro, 2008. 105p. Orientador: Prof. Dr. Nilson Alves de Moraes. .......................................................................................... Gallery of the Popular Artist: tradition, identity, market. BAIA, Luiz César dos Santos. Gallery of the Popular Artist: tradition, ident...

  7. Shock Induced Emission from Sapphire in High-Pressure Phase of Rh2O3 (Ⅱ) Structure

    Institute of Scientific and Technical Information of China (English)

    ZHANG Dai-Yu; LIU Fu-Sheng; HAO Gao-Yu; SUN Yu-Huai

    2007-01-01

    @@ A distinct optical emission from the Rh2 O3 (Ⅱ) structural sapphire is observed under shock compression of 125,132, and 143 Gpa. The emission intensity continuously increases with the thickness of shocked sapphire. The colour temperature is determined to be about 4000K, which is obviously smaller than the reported value of the alpha phase alumina at the pressures below 80 Gpa. The present results suggest that the structural transformation will cause an obvious change of optical property in sapphire.

  8. Induced caving by blasting: innovative experiments in blasting gallery panels of underground coal mines of India

    Energy Technology Data Exchange (ETDEWEB)

    Roy, P.P.; Sawmliana, C.; Bhagat, N.K.; Madhu, M. [CMRI, Dhanbad (India). Blasting Dept.

    2003-04-01

    Induced caving by blasting during depillaring of panels in underground coal mines has received limited attention. This technique has become an integral part of a mining operation known as the blasting gallery (BG) method in India. Systematical deep hole (16-30 m) blasting has been successfully carried out from underground split galleries in BG panels. A study of drilling and blasting parameters, gas hazards, strata behaviour and ground vibration was undertaken as part of a research project for the Indian Ministry of Coal and Mines. Strata behaviour during blasting and ground movements were critically investigated. All experiments were conducted using newly developed explosive and detonating cord systems. A new blast damage index is proposed for damage assessment of the underground roof and pillars of BG panels. Useful mathematical formulas are described as an aid to future design.

  9. From the Street to Art Galleries : How Graffiti Became a Legitimate Art Form

    OpenAIRE

    Diallo, David

    2014-01-01

    In this article, I explain why graffiti was established almost immediately as a legitimate art form; unlike other hip hop expressive forms such as rap music or break-dancing. I examine the development of this graphic practice and consider the structural elements responsible for its transition from juvenile clandestine expressive form to artistic profession. I especially argue that institutional commentators (journalists, art critics, academics), as much as galleries owners and art sellers, we...

  10. Measurements of indoor {sup 222}Rn concentration in two art galleries

    Energy Technology Data Exchange (ETDEWEB)

    Carneiro, Luana Gomes; Braz, Delson; Jesus, Edgar Francisco de, E-mail: carneiro@ird.gov.b [Coordenacao dos Programas de Pos-graduacao de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil); Cunha, Kenya Dias da; Medeiros, Geiza; Zouain, Felipe, E-mail: kenya@ird.gov.b [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Pitassi, Gabriel; Leite, Carlos Barros [Pontificia Universidade Catolica do Rio de Janeiro (PUC-Rio), Rio de Janeiro, RJ (Brazil); Cardoso, Katia, E-mail: cardoso@ien.gov.b [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2009-07-01

    It is point out that radon and their decay products in environment give high dose to human lung. Studies indicate that the indoor radon inhalation by humans has been considered probably the second most important cause of lung cancer after of smoking. A passive-type radon detector was used for measuring indoor radon concentration in two art galleries at Rio de Janeiro city during 90 days January to March, 2009. The aim of this study is to evaluate the occupational and public radon exposure in art galleries and museums. This paper shows the preliminary results of samples collected at two art galleries located in Gavea, Rio de Janeiro city. 30 LEXAN (GE) track detectors were exposed in the air (indoor as well as outdoor). The samples were collected in the same building which is a construction of XIX century. The analysis of the results suggests that the {sup 222}Rn concentration levels are different in both sampling site, in closed environmental, demonstrating that, although the construction materials are the same the absence of circulating air is a factor very important to increase the concentration of indoor Rn. (author)

  11. Presence and diversity of Streptomyces in Dendroctonus and sympatric bark beetle galleries across North America.

    Science.gov (United States)

    Hulcr, Jiri; Adams, Aaron S; Raffa, Kenneth; Hofstetter, Richard W; Klepzig, Kier D; Currie, Cameron R

    2011-05-01

    Recent studies have revealed several examples of intimate associations between insects and Actinobacteria, including the Southern Pine Beetle Dendroctonus frontalis and the Spruce Beetle Dendroctonus rufipennis. Here, we surveyed Streptomyces Actinobacteria co-occurring with 10 species of Dendroctonus bark beetles across the United States, using both phylogenetic and community ecology approaches. From these 10 species, and 19 other scolytine beetles that occur in the same trees, we obtained 154 Streptomyces-like isolates and generated 16S sequences from 134 of those. Confirmed 16S sequences of Streptomyces were binned into 36 distinct strains using a threshold of 0.2% sequence divergence. The 16S rDNA phylogeny of all isolates does not correlate with the distribution of strains among beetle species, localities, or parts of the beetles or their galleries. However, we identified three Streptomyces strains occurring repeatedly on Dendroctonus beetles and in their galleries. Identity of these isolates was corroborated using a house-keeping gene sequence (efTu). These strains are not confined to a certain species of beetle, locality, or part of the beetle or their galleries. However, their role as residents in the woodboring insect niche is supported by the repeated association of their 16S and efTu from across the continent, and also having been reported in studies of other subcortical insects.

  12. Nanoscratch Characterization of GaN Epilayers on c- and a-Axis Sapphire Substrates

    Directory of Open Access Journals (Sweden)

    Wen Hua-Chiang

    2010-01-01

    Full Text Available Abstract In this study, we used metal organic chemical vapor deposition to form gallium nitride (GaN epilayers on c- and a-axis sapphire substrates and then used the nanoscratch technique and atomic force microscopy (AFM to determine the nanotribological behavior and deformation characteristics of the GaN epilayers, respectively. The AFM morphological studies revealed that pile-up phenomena occurred on both sides of the scratches formed on the GaN epilayers. It is suggested that cracking dominates in the case of GaN epilayers while ploughing during the process of scratching; the appearances of the scratched surfaces were significantly different for the GaN epilayers on the c- and a-axis sapphire substrates. In addition, compared to the c-axis substrate, we obtained higher values of the coefficient of friction (μ and deeper penetration of the scratches on the GaN a-axis sapphire sample when we set the ramped force at 4,000 μN. This discrepancy suggests that GaN epilayers grown on c-axis sapphire have higher shear resistances than those formed on a-axis sapphire. The occurrence of pile-up events indicates that the generation and motion of individual dislocation, which we measured under the sites of critical brittle transitions of the scratch track, resulted in ductile and/or brittle properties as a result of the deformed and strain-hardened lattice structure.

  13. Growth and Crystal Orientation of ZnTe on m-Plane Sapphire with Nanofaceted Structure

    Science.gov (United States)

    Nakasu, Taizo; Sun, Wei-Che; Kobayashi, Masakazu; Asahi, Toshiaki

    2016-11-01

    ZnTe thin films on sapphire substrate with nanofaceted structure have been studied. The nanofaceted structure of the m-plane (10-10) sapphire was obtained by heating the substrate at above 1100°C in air, and the r-plane (10-12) and S-plane (1-101) were confirmed. ZnTe layers were prepared on the nanofaceted m-plane sapphire substrates by molecular beam epitaxy (MBE). The effect of the nanofaceted structure on the orientation of the thin films was examined based on x-ray diffraction (XRD) pole figures. Transmission electron microscopy (TEM) was also employed to characterize the interface structures. The ZnTe layer on the nanofaceted m-plane sapphire substrate exhibited (331)-plane orientation, compared with (211)-plane without the nanofaceted structure. After thermal treatment, the m-plane surface vanished and (211) layer could not be formed because of the lack of surface lattice matching. On the other hand, (331)-plane thin film was formed on the nanofaceted m-plane sapphire substrate, since the (111) ZnTe domains were oriented on the S-facet. The orientation of the ZnTe epilayer depended on the atomic ordering on the surface and the influence of the S-plane.

  14. Carbon nanotube assisted Lift off of GaN layers on sapphire

    Science.gov (United States)

    Long, Hao; Feng, Xiaohui; Wei, Yang; Yu, Tongjun; Fan, Shoushan; Ying, Leiying; Zhang, Baoping

    2017-02-01

    Laser lift off (LLO) was one of the most essential processes in fabrication of vertical GaN-based LEDs. However, traditional laser lift off of GaN on sapphire substrates needed high laser energy threshold, which deteriorated the GaN crystal. In this paper, it was found that inserting carbon nanotube between GaN and sapphire could effectively reduce the laser energy threshold in GaN LLO, from 1.5 J /cm2 of conventional GaN/sapphire to 1.3 J /cm2 of CNT inserted GaN/sapphire. The temperature distributions at the GaN/sapphire interfaces with and without CNTs were simulated by the finite elements calculation under laser irradiation. It was found that, due to the higher laser absorption coefficient of CNT, the CNT played as a powerful heating wire, sending out the thermal outside to elevate the GaN's temperature, and thus reduce the laser threshold for LLO. Raman and photoluminescence measurements indicated that residual stress of GaN membranes was as small as 0.3 GPa by the carbon nanotube assisted LLO. This work not only opens new application of CNTs, but also demonstrates the potential of high performance blue and green LEDs.

  15. Variable Energy Positron Annihilation Spectroscopy of GaN Grown on Sapphire Substrates with MOCVD

    Institute of Scientific and Technical Information of China (English)

    HU Yi-Fan; C.D. Beling; S. Fung

    2005-01-01

    @@ Depth profiled Doppler broadening of positron annihilation spectroscopy (DBPAS), which is also called the variable energy positron annihilation spectroscopy (VEPAS), is used in characterization of GaN grown on sapphire substrates with metal-organic chemical vapour deposition (MOCVD). The GaN film and the film/substrate interface are investigated. The VEPFIT (variable energy positron fit) software was used for analysing the data,and the positron diffusion length of the sapphire is obtained. The results suggest that there is a highly defected region near the GaN/sapphire interface. This thin dislocated region is generated at the film/substrate interface to relieve the strain. Effects of implantation dose on defect formation, for the GaN/Sapphire samples, which implanted by Al+ ions, are also investigated. Studies on Al+ implanted GaN films (not including the interface and sapphire) have revealed that there are two different regions of implantation damage. For the low Al+ implantation dose samples, in the region close to the surface, defects are mainly composed of vacancy pairs with small amount of vacancy clusters, and in the interior region of the film the positron traps are vacancy clusters without micro-voids. For the highest dose sample, however, some positron trap centres are in the form of micro-voids in the second region.

  16. Sapphire scintillation tests for cryogenic detectors in the Edelweiss dark matter search

    Energy Technology Data Exchange (ETDEWEB)

    Luca, M

    2007-07-15

    Identifying the matter in the universe is one of the main challenges of modern cosmology and astrophysics. An important part of this matter seems to be made of non-baryonic particles. Edelweiss is a direct dark matter search using cryogenic germanium bolometers in order to look for particles that interact very weakly with the ordinary matter, generically known as WIMPs (weakly interacting massive particles). An important challenge for Edelweiss is the radioactive background and one of the ways to identify it is to use a larger variety of target crystals. Sapphire is a light target which can be complementary to the germanium crystals already in use. Spectroscopic characterization studies have been performed using different sapphire samples in order to find the optimum doping concentration for good low temperature scintillation. Ti doped crystals with weak Ti concentrations have been used for systematic X ray excitation tests both at room temperature and down to 30 K. The tests have shown that the best Ti concentration for optimum room temperature scintillation is 100 ppm and 50 ppm at T = 45 K. All concentrations have been checked by optical absorption and fluorescence. After having shown that sapphire had interesting characteristics for building heat-scintillation detectors, we have tested if using a sapphire detector was feasible within a dark matter search. During the first commissioning tests of Edelweiss-II, we have proved the compatibility between a sapphire heat scintillation detector and the experimental setup. (author)

  17. Whispers of the Unspeakable: New York and Montreal Newspaper Coverage of the Oscar Wilde Trials in 1895

    OpenAIRE

    Greg Robinson

    2015-01-01

    Greg Robinson’s article “Whispers of the Unspeakable: New York and Montreal Newspaper Coverage of the Oscar Wilde Trials in 1895,” originally published in 2010 in the French-language journal Rue des Beaux Arts, no. 24 (2010), is here republished and—with much gratitude—translated (for the original text, please see http://www.oscholars.com/RBA/twenty-four/24.7/Articles.htm). Robinson’s transnational study focuses on how reading the specific language of newspaper reports of the Oscar Wilde case...

  18. Revelation of Causes of Colour Change in Beryllium-Treated Sapphires

    Institute of Scientific and Technical Information of China (English)

    Pichet Limsuwan; Siwaporn Meejoo; Asanee Somdee; Kheamrutai Thamaphat; Treedej Kittiauchawal; Atitaya Siripinyanond; Jurek Krzystck

    2008-01-01

    Blue sapphires are treated with Be in oxidizing atmosphere to change the blue colour into yellow. Untreated and Be-treated samples are examined using laser ablation inductively coupled-plasma-mass spectrometry (LA-ICP-MS), electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectroscopy. The results show that the yellow colouration in Be-heated blue sapphires is not due to Be diffusion from the surface of sapphire. Be behaves as a sole catalyst in this process. We find that the charge transfer between the ferrous (Fe2+) and ferric (Fe3+) is the reason of the colour change. The above conclusions are confirmed by ESR measurements to determine the connections between the Fe3+ ions before and after Be-treated heat treatments.

  19. Sapphire hard X-ray Fabry-Perot resonators for synchrotron experiments.

    Science.gov (United States)

    Tsai, Yi Wei; Wu, Yu Hsin; Chang, Ying Yi; Liu, Wen Chung; Liu, Hong Lin; Chu, Chia Hong; Chen, Pei Chi; Lin, Pao Te; Fu, Chien Chung; Chang, Shih Lin

    2016-05-01

    Hard X-ray Fabry-Perot resonators (FPRs) made from sapphire crystals were constructed and characterized. The FPRs consisted of two crystal plates, part of a monolithic crystal structure of Al2O3, acting as a pair of mirrors, for the backward reflection (0 0 0 30) of hard X-rays at 14.3147 keV. The dimensional accuracy during manufacturing and the defect density in the crystal in relation to the resonance efficiency of sapphire FPRs were analyzed from a theoretical standpoint based on X-ray cavity resonance and measurements using scanning electron microscopic and X-ray topographic techniques for crystal defects. Well defined resonance spectra of sapphire FPRs were successfully obtained, and were comparable with the theoretical predictions.

  20. High Temperature Testing with Sapphire Fiber White-Light Michelson Interferometers

    Science.gov (United States)

    Barnes, A.; Pedrazzani, J.; May, R.; Murphy, K.; Tran, T.; Coate, J.

    1996-01-01

    In the design of new aerospace materials, developmental testing is conducted to characterize the behavior of the material under severe environmental conditions of high stress, temperature, and vibration. But to test these materials under extreme conditions requires sensors that can perform in harsh environments. Current sensors can only monitor high temperature test samples using long throw instrumentation, but this is inherently less accurate than a surface mounted sensor, and provides no means for fabrication process monitoring. A promising alternative is the use of sapphire optical fiber sensors. Sapphire is an incredibly rugged material, being extremely hard (9 mhos), chemically inert, and having a melting temperature (over 2000 C). Additionally, there is a extensive background of optical fiber sensors upon which to draw for sapphire sensor configurations.

  1. Stability of trapped charges in sapphires and alumina ceramics: Evaluation by secondary electron emission

    Science.gov (United States)

    Zarbout, K.; Si Ahmed, A.; Moya, G.; Bernardini, J.; Goeuriot, D.; Kallel, A.

    2008-03-01

    The stability of trapped charges in sapphires and alumina ceramics is characterized via an experimental parameter expressing the variation of the secondary electron emission yield between two electron injections performed in a scanning electron microscope. Two types of sapphires and polycrystalline alumina, which differ mainly by their impurity content, are investigated in the temperature range 300-663K. The stable trapping behavior in sapphires is attributed to trapping in different defects, whose nature depends on the purity level. In alumina ceramics, the ability to trap charges in a stable way is stronger in samples of high impurity content. In the low impurity samples, stable trapping is promoted when the grain diameter decreases, whereas the reverse is observed in high impurity materials. These behaviors can stem from a gettering effect occurring during sintering. The strong dependence of the variation of the secondary electron emission yield on the grain diameter and impurities enables a scaling of the stable trapping ability of alumina materials.

  2. Temperature and thermal stress evolutions in sapphire crystal during the cooling process by heat exchanger method

    Science.gov (United States)

    Ma, Wencheng; Zhao, Wenhan; Wu, Ming; Ding, Guoqiang; Liu, Lijun

    2017-09-01

    Transient numerical calculations were carried out to predict the evolutions of temperature and thermal stress in sapphire single crystal during the cooling process by heat exchanger method (HEM). Internal radiation in the semitransparent sapphire crystal was taken into account using the finite volume method (FVM) in the global heat transfer model. The numerical results seem to indicate that the narrow bottom region of the sapphire crystal is subjected to high thermal stress during the cooling process, which could be responsible for the seed cracking of the as-grown crystal, while the thermal stress is relatively small in the central main body of the crystal, and is less than 10 MPa during the whole cooling process. The fast decrease of the thermal stress in the bottom region of the crystal during the initial stage of cooling process is dominated by the reduction of the cooling helium gas in the heat exchanger shaft, and is not significantly affected by the heating power reduction rate.

  3. Rate of F center formation in sapphire under low-energy low-fluence Ar+ irradiation

    Science.gov (United States)

    Epie, E. N.; Wijesundera, D. N.; Tilakaratne, B. P.; Chen, Q. Y.; Chu, W. K.

    2016-03-01

    Ionoluminescence, optical absorption spectroscopy and Rutherford backscattering spectrometry channelling (RBS-C) have been used to study the rate of F center formation with fluence in 170 keV Ar+ irradiated single crystals of α-Al2O3 (sapphire) at room temperature. Implantation fluences range between 1013 cm-2 and 5 ×1014 cm-2. F center density (NF) has been found to display an initial rapid linear increase with Ar+ fluence followed by saturation to a maximum value of 1.74 ×1015 cm-2. Experimental results show a 1-1 correlation between radiation damage in the oxygen sublattice and F center density. This suggest F center kinetics in sapphire under low-energy low-fluence Ar irradiation is a direct consequence of dynamic competition between oxygen defect creation and recombination. An attempt has also been made to extend this discussion to F center kinetics in sapphire under swift heavy ion irradiation.

  4. High-pressure sapphire cell for phase equilibria measurements of CO2/organic/water systems.

    Science.gov (United States)

    Pollet, Pamela; Ethier, Amy L; Senter, James C; Eckert, Charles A; Liotta, Charles L

    2014-01-24

    The high pressure sapphire cell apparatus was constructed to visually determine the composition of multiphase systems without physical sampling. Specifically, the sapphire cell enables visual data collection from multiple loadings to solve a set of material balances to precisely determine phase composition. Ternary phase diagrams can then be established to determine the proportion of each component in each phase at a given condition. In principle, any ternary system can be studied although ternary systems (gas-liquid-liquid) are the specific examples discussed herein. For instance, the ternary THF-Water-CO2 system was studied at 25 and 40 °C and is described herein. Of key importance, this technique does not require sampling. Circumventing the possible disturbance of the system equilibrium upon sampling, inherent measurement errors, and technical difficulties of physically sampling under pressure is a significant benefit of this technique. Perhaps as important, the sapphire cell also enables the direct visual observation of the phase behavior. In fact, as the CO2 pressure is increased, the homogeneous THF-Water solution phase splits at about 2 MPa. With this technique, it was possible to easily and clearly observe the cloud point and determine the composition of the newly formed phases as a function of pressure. The data acquired with the sapphire cell technique can be used for many applications. In our case, we measured swelling and composition for tunable solvents, like gas-expanded liquids, gas-expanded ionic liquids and Organic Aqueous Tunable Systems (OATS)(1-4). For the latest system, OATS, the high-pressure sapphire cell enabled the study of (1) phase behavior as a function of pressure and temperature, (2) composition of each phase (gas-liquid-liquid) as a function of pressure and temperature and (3) catalyst partitioning in the two liquid phases as a function of pressure and composition. Finally, the sapphire cell is an especially effective tool to gather

  5. The Influence of Surface Anisotropy Crystalline Structure on Wetting of Sapphire by Molten Aluminum

    Science.gov (United States)

    Aguilar-Santillan, Joaquin

    2013-05-01

    The wetting of sapphire by molten aluminum was investigated by the sessile drop technique from 1073 K to 1473 K (800 °C to 1200 °C) at PO2 <10-15 Pa under Ar atmosphere. This study focuses on sapphire crystalline structure and its principle to the interface. The planes " a" and " b" are oxygen terminated structures and wet more by Al, whereas the " c" plane is an aluminum terminated structure. A wetting transition at 1273 K (1000 °C) was obtained and a solid surface tension proves the capillarity trends of the couple.

  6. Synthesis of ZnO nanocrystals in sapphire by ion implantation and vacuum annealing

    Science.gov (United States)

    Marques, C.; Franco, N.; Alves, L. C.; da Silva, R. C.; Alves, E.; Safran, G.; McHargue, C. J.

    2007-04-01

    The synthesis of embedded ZnO nanoparticles in m-cut sapphire was achieved through high fluence Zn ion implantation, 0.9 × 1017 cm-2 at room temperature, followed by annealing at 1000 °C in vacuum. In c-cut samples subjected to similar annealing conditions only buried precipitates of Zn form. TEM results in these samples show a high concentration of faceted precipitates distributed along the c-plane and the presence of Kirkendall voids distributed along the entire implanted region. In both cases a strong loss of Zn is observed upon annealing, which depends on the sapphire host orientation.

  7. Tunable Sum Frequency Mixing of a Ti∶sapphire Laser and a Nd∶YAG Laser

    Institute of Scientific and Technical Information of China (English)

    DING Xin; YAO Jianquan; YU Yizhong; YU Xuanyi; XU Jingjun; ZHANG Guangyin

    2001-01-01

    In this paper the theoretical and experimental results of sum-frequency mixing of a Ti∶sapphire laser and a 1.064 μm Nd∶YAG laser are presented. By using two KTP crystals cut at θ=76° and 85° (φ=90° in both crystals), respectively, the sum-frequency mixing tuning range from 459.3 to 509.6 nm in one Ti∶sapphire laser setup is experimentally achieved. The maximum output energy was 14.6 mJ and the energy conversion efficiency was up to 15.2%.

  8. Synthesis of ZnO nanocrystals in sapphire by ion implantation and vacuum annealing

    Energy Technology Data Exchange (ETDEWEB)

    Marques, C. [LFI, Dep. Fisica, Instituto Tecnologico e Nuclear, E.N. 10, 2686-953 Sacavem (Portugal); Centro Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Franco, N. [LFI, Dep. Fisica, Instituto Tecnologico e Nuclear, E.N. 10, 2686-953 Sacavem (Portugal); Centro Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Alves, L.C. [LFI, Dep. Fisica, Instituto Tecnologico e Nuclear, E.N. 10, 2686-953 Sacavem (Portugal); Centro Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Silva, R.C. da [LFI, Dep. Fisica, Instituto Tecnologico e Nuclear, E.N. 10, 2686-953 Sacavem (Portugal) and Centro Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal); Alves, E. [LFI, Dep. Fisica, Instituto Tecnologico e Nuclear, E.N. 10, 2686-953 Sacavem (Portugal) and Centro Fisica Nuclear da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisbon (Portugal)]. E-mail: ealves@itn.pt; Safran, G. [Research Institute for Technical Physics and Materials Science, H-1525 Budapest (Hungary); McHargue, C.J. [University of Tennessee, Knoxville, TN 37996-0750 (United States)

    2007-04-15

    The synthesis of embedded ZnO nanoparticles in m-cut sapphire was achieved through high fluence Zn ion implantation, 0.9 x 10{sup 17} cm{sup -2} at room temperature, followed by annealing at 1000 deg. C in vacuum. In c-cut samples subjected to similar annealing conditions only buried precipitates of Zn form. TEM results in these samples show a high concentration of faceted precipitates distributed along the c-plane and the presence of Kirkendall voids distributed along the entire implanted region. In both cases a strong loss of Zn is observed upon annealing, which depends on the sapphire host orientation.

  9. Birefringence measurements in single crystal sapphire and calcite shocked along the a axis

    Science.gov (United States)

    Tear, Gareth R.; Chapman, David J.; Eakins, Daniel E.; Proud, William G.

    2017-01-01

    Calcite and sapphire were shock compressed along the direction (a axis) in a plate impact configuration. Polarimetery and Photonic Doppler Velocimetery (PDV) were used to measure the change in birefringence with particle velocity in the shock direction. Results for sapphire agree well with linear photoelastic theory and current literature showing a linear relationship between birefringence and particle velocity up to 310 m s-1. A maximum change in birefringence of 5% was observed. Calcite however showed anomolous behaviour with no detectable change in birefringence (less than 0.1%) over the range of particle velocities studied (up to 75 m s-1).

  10. Intracavity frequency doubling of CW Ti:Sapphire laser utilising BiBO nonlinear crystal

    DEFF Research Database (Denmark)

    Thorhauge, Morten; Mortensen, Jesper Liltorp; Tidemand-Lichtenberg, Peter

    Utilising BiBO nonlinear crystal frequency doubling a Ti:Sapphire CW laser gave 100 mW at 405 nm and 53 mW at 392 nm. Stability proved excellent without servo control. Broad tunability was shown around 392 nm.......Utilising BiBO nonlinear crystal frequency doubling a Ti:Sapphire CW laser gave 100 mW at 405 nm and 53 mW at 392 nm. Stability proved excellent without servo control. Broad tunability was shown around 392 nm....

  11. Behaviors of optical and chemical state of Nb+ implanted sapphire after annealing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The behavior of the radiation damage of sapphire crystal, produced by implantation with 380 keV Nb+ ion followed by annealing in a series of steps from 500 to 1100℃C at reducing atmosphere, was investigated in optical absorption and XPS measurements. It is found that the implanted niobium in sapphire is in different local environments with different chemical states after the annealing. The changes in optical density (OD) from the bands, based on the well known F-type centers, show that the annealing behavior of the radiation damage may be divided into different stages due to different mechanisms.

  12. Measurement for titanium density distribution on Ti:sapphire rods for high intensity pump source

    Energy Technology Data Exchange (ETDEWEB)

    Usami, Tsutomu; Nishimura, Akihiko; Sugiyama, Akira [Japan Atomic Energy Research Inst., Kizu, Kyoto (Japan). Kansai Research Establishment

    2001-10-01

    A Ti:sapphire rod of 190 mm length made by Czochralski (CZ) technique was used in the flashlamp pumped high intensity laser for Yb:glass chirped pulse amplification. In the absorption spectroscopy of the rod immersed in an index matching liquid of methylene iodide, heterogeneous Ti{sup 3+} density distribution was measured along the direction of length. It has been first clarified that the Ti:sapphire rod grown by the CZ technique has 20% difference of the Ti{sup 3+} density at the both ends. (author)

  13. Sapphire: Relation between luminescence of starting materials and luminescence of single crystals

    Science.gov (United States)

    Mogilevsky, R.; Nedilko, S.; Sharafutdinova, L.; Burlay, S.; Sherbatskii, V.; Boyko, V.; Mittl, S.

    2009-10-01

    A relation between photoluminescence (PL) characteristics of different starting materials used for crystal growth and un-doped sapphire single crystals manufactured using various methods of crystal growth (Kyropolus, HEM, Czochralski, and EFG) was found. The crystals grown using the Verneuil starting material exhibited significant PL when any method of crystal growth was used. On the contrary, sapphire samples grown by the same technologies wherein the starting material was EMT HPDA R revealed very low PL. (HPDA R is produced by EMT, Inc., with proprietary and patented technology.)

  14. High diversity and low specificity of chaetothyrialean fungi in carton galleries in a neotropical ant-plant association.

    Directory of Open Access Journals (Sweden)

    Maximilian Nepel

    Full Text Available New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the - usually undescribed - fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes. Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae, the ant Azteca brevis (Formicidae: Dolichoderinae and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

  15. Embedding plurality: exploring participatory practice in the development of a new permanent gallery

    Directory of Open Access Journals (Sweden)

    Katy Bunning

    2015-05-01

    Full Text Available Increasing numbers of museums and galleries worldwide have developed an array of working practices that might be termed 'participatory' or 'co-creative', which seek to involve visitors, non-visitors, community and interest groups with diverse forms of expertise and perspective in their activities. Frequently the central aim of such practices has been to strengthen relationships between a museum and its audiences through projects that are jointly conceived and developed with local communities. However, relatively little attention has been given to participatory practice within the work of larger institutions, particularly those with a national and international remit, reach and audience base, where participatory practices are adopted to enrich the development and content of new permanent displays (aimed at large and diverse audiences. Drawing on a single case study – the development of the permanent Information Age gallery at the Science Museum in London, which opened in 2014 – this paper aims to reflect upon the extent to which existing concepts, theories and approaches to participation and co-creation resonate with museum work of this kind. Unlike many participatory practices internationally, the range of projects and activities utilised in the development of Information Age were driven less by a desire to share authority and decision-making with communities outside the museum and more by a concern to foster involvement with diverse communities of interest in the making of a major gallery and to generate and embed plural perspectives on the objects and stories presented within it. This paper raises further questions around how participatory work is perceived, valued and shared across the sector.

  16. Victorian era esthetic and restorative dentistry: an advertising trade card gallery.

    Science.gov (United States)

    Croll, Theodore P; Swanson, Ben Z

    2006-01-01

    A chief means of print advertising in the Victorian era was the "trade card." Innumerable products, companies, and services were highlighted on colorful chromolithographic trade cards, and these became desirable collectible objects which were pasted into scrapbooks and enjoyed by many families. Dentistry- and oral health-related subjects were often depicted on Victorian trade cards, and esthetic and restorative dentistry themes were featured. This review describes the history of advertising trade cards and offers a photographic gallery of dentistry-related cards of the era.

  17. Orchid bee (Hymenoptera: Apidae) community from a gallery forest in the Brazilian Cerrado.

    Science.gov (United States)

    Silva, Francinaldo S

    2012-06-01

    The orchid bees are a very important group of pollinators distributed in the Neotropics. Although a lot of studies concerning male euglossine bees have been done in this region, few works have so far been carried out in the Cerrado biome. This manuscript has the main objective to present the orchid bee community from a Gallery Forest in the Northeastern Brazilian Cerrado landscape, taking account the species composition, abundance, seasonality and hourly distribution. Male euglossine bees were collected monthly from October 2007 to May 2009, in the Reserva Florestal da Itamacaoca belonging to the Companhia de Agua e Esgoto do Maranhão, in Chapadinha municipality, Maranhão State. The scents eucalyptol, eugenol and vanillin were utilized, between 07:00 and 17:00hr, to attract the euglossine males. Cotton balls were dampened with the scents and suspended by a string on tree branches 1.5m above soil level, set 8m from one another. The specimens were captured with entomological nets, killed with ethyl acetate and transported to the laboratory to be identified. A total of 158 individuals and 14 species of bees were recorded. The genus Eulaema was the most representative group of euglossine bees in relation to the total number of the sampled individuals, accounting for 50.6% of bees followed by Euglossa (26.6%), Eufriesea (15.2%) and Exaerete (7.6%). The most frequent species were Eulaema nigrita (27.8%), Eulaema cingulara (19%) and Euglossa cordata (18.3%). Many species typical of forested environments were found in samples, like Euglossa avicula, Euglossa violaceifrons and Eulaema meriana, emphasizing the role played by the Gallery Forests as bridge sites to connect the two great biomes of Amazonia and Atlantic Forest. The occurrence of Exaerete guaykuru represents the second record of this species for the Neotropical region, and both records coming from the Gallery Forest zones. The male euglossine bees were sampled mainly in the dry season, where 62.5% of the

  18. Moving the body painting into the art gallery — knowing about and appreciating works of Aboriginal art

    Directory of Open Access Journals (Sweden)

    Howard Morphy

    2011-06-01

    Full Text Available The paper focuses on two kinds of relationship: between Western fine art and Indigenous art, and between anthropological and art historical approaches to understanding and appreciating works of art. The primary focus is on the process by which Australian Aboriginal art came to be incorporated within galleries of fine art. This process brought both kinds of relationships to the fore in the contemporary context and challenged established boundaries exemplified by the distinction between the museum and the art gallery. It is argued that objects encompassed within the category of fine art come from very different cultural traditions and historical backgrounds. The methods of both art history and anthropology can be productively applied in analysing the forms and significance of artworks in their social and cultural contexts. The paper concludes by considering some of the implications of the co-presence of artworks from different cultural traditions in the same contemporary gallery spaces.

  19. The F1-F2 vowel chart for Czech whispered vowels a, e, i, o, u.

    Science.gov (United States)

    Grepl, Michal; Furst, Tomas; Pesak, Josef

    2007-12-01

    The aim of this contribution is to present the formant chart of the Czech vowels a, e, i, o, u and show that this can be achieved by means of digital methods of sound processing. A group of 35 Czech students of the Pedagogical Faculty of Palacky University was tested and a record of whispered vowels was taken from each of them. The record was digitalized and processed by the Discrete Fourier Trasform. The result is the power spectrum of the individual vocals - the graphic output consists of a plot of the relative power of individual frequencies in the original sound. The values of the first two maxima which represent the first and the second formants were determined from the graph. The values were plotted on a formant chart. Altogether, 175 spectral analyses of individual vowels were performed. In the resulting power spectrum, the first and the second formant frequencies were identified. The first formant was plotted against the second one and pure vocal formant regions were identified. Frequency bands for the Czech vowel "a" were circumscribed between 850 and 1150 Hz for first formant (F1) and between 1200 and 2000 Hz for second formant (F2). Similarly, borders of frequency band for vowel "e" they were 700 and 950 Hz for F1 and 1700 and 3000 Hz for F2. For vowel "i" 300 and 450 Hz for F1 and 2000 and 3600 Hz for F2, for vowel "o" 600 and 800 Hz for F1 and 600 and 1400 Hz for F2, for vowel "u" 100 and 400 Hz for F1 and 400 and 1200 Hz for F2. At low frequencies it is feasible to invoke the source-filter model of voice production and associate vowel identity with frequencies of the first two formants in the voice spectrum. On the other hand, subject to intonation, singing or other forms of exposed voice (such as emotional speech, focused speech), the formant regions tend to spread. In spectral analysis other frequencies dominate, so specific formant frequency bands are not easily recognizable. Although the resulting formant map is not much different from the formant

  20. Femtosecond Ti:sapphire cryogenic amplifier with high gain and MHz repetition rate

    DEFF Research Database (Denmark)

    Dantan, Aurelien Romain; Laurat, Julien; Ourjoumtsev, Alexei

    2007-01-01

    We demonstrate high gain amplification of 160-femtosecond pulses in a compact double-pass cryogenic Ti:sapphire amplifier. The setup involves a negative GVD mirrors recompression stage, and operates with a repetition rate between 0.2 and 4 MHz with a continuous pump laser. Amplification factors...

  1. Fully-depleted silicon-on-sapphire and its application to advanced VLSI design

    Science.gov (United States)

    Offord, Bruce W.

    1992-01-01

    In addition to the widely recognized advantages of full dielectric isolation, e.g., reduced parasitic capacitance, transient radiation hardness, and processing simplicity, fully-depleted silicon-on-sapphire offers reduced floating body effects and improved thermal characteristics when compared to other silicon-on-insulator technologies. The properties of this technology and its potential impact on advanced VLSI circuitry will be discussed.

  2. Deep-ultraviolet frequency metrology with a narrowband titanium:sapphire laser

    NARCIS (Netherlands)

    Hannemann, S.

    2007-01-01

    Within the framework of this thesis resaerch project a narrow band titanium:sapphire laser was built. It provides nanosecond pulses that are subsequently upconverted to the deep ultraviolet frequency range. Absolute frequency calibration is achieved by linking the injection seeding light to a

  3. Low Temperature Rhombohedral Single Crystal SiGe Epitaxy on c-plane Sapphire

    Science.gov (United States)

    Duzik, Adam J.; Choi, Sang H.

    2016-01-01

    Current best practice in epitaxial growth of rhombohedral SiGe onto (0001) sapphire (Al2O3) substrate surfaces requires extreme conditions to grow a single crystal SiGe film. Previous models described the sapphire surface reconstruction as the overriding factor in rhombohedral epitaxy, requiring a high temperature Al-terminated surface for high quality films. Temperatures in the 850-1100 C range were thought to be necessary to get SiGe to form coherent atomic matching between the (111) SiGe plane and the (0001) sapphire surface. Such fabrication conditions are difficult and uneconomical, hindering widespread application. This work proposes an alternative model that considers the bulk sapphire structure and determines how the SiGe film nucleates and grows. Accounting for thermal expansion effects, calculations using this new model show that both pure Ge and SiGe can form single crystal films in the 450-550 C temperature range. Experimental results confirm these predictions, where x-ray diffraction and atomic force microscopy show the films fabricated at low temperature rival the high temperature films in crystallographic and surface quality. Finally, an explanation is provided for why films of comparable high quality can be produced in either temperature range.

  4. Laser-assisted microstructuring for Ti:sapphire channel-waveguide fabrication

    NARCIS (Netherlands)

    Crunteanu, A.; Pollnau, Markus; Jänchen, G.; Hibert, C.; Hoffmann, P.; Salathé, R.P.; Eason, R.W.; Shepherd, D.P.

    We report on the fabrication of Ti:sapphire channel waveguides. Such channel waveguides are of interest, e.g., as low-threshold tunable lasers. We investigated several structuring methods including ion beam implantation followed by wet chemical etching strip loading by polyimide spin coating and

  5. Study on Inclusions in Large Sapphire Optical Crystal Grown by SAPMAC Method

    Institute of Scientific and Technical Information of China (English)

    WANG Gui-gen; ZHANG Ming-fu; ZUO Hong-bo; HE Xiao-dong; HAN Jie-cai

    2006-01-01

    The sapphire (Al2O3) single crystal is a kind of excellent infrared transmission window materials. A large-sized sapphire (Φ225 mm×205 mm, 27.5 kg) was grown by SAPMAC method (sapphire growth technique with micro-pulling and shoulder-expanding at cooled center). Several kinds of inclusion in the large sapphire crystal were investigated by means of an optical microscopy (OM), scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The experimental results show that most inclusions are consisted of solid metallic and non-metallic particles as well as gas pores caused by the impurity of alumina as the raw material, the thermal dissociation of aluminum oxide melt and the reaction of the melt to the crucible material (Mo) at high temperatures. It is also found that in different crystal regions the inclusions are of varied sizes, morphology and chemical compositions. Finally, the measures to reduce and eliminate the inclusions are proposed to improve the crystal quality.

  6. Neutron reflectivity study of substrate surface chemistry effects on supported phospholipid bilayer formation on (1120) sapphire.

    Energy Technology Data Exchange (ETDEWEB)

    Oleson, Timothy A. [University of Wisconsin, Madison; Sahai, Nita [University of Akron; Wesolowski, David J [ORNL; Dura, Joseph A [ORNL; Majkrzak, Charles F [ORNL; Giuffre, Anthony J. [University of Wisconsin, Madison

    2012-01-01

    Oxide-supported phospholipid bilayers (SPBs) used as biomimetric membranes are significant for a broad range of applications including improvement of biomedical devices and biosensors, and in understanding biomineralization processes and the possible role of mineral surfaces in the evolution of pre-biotic membranes. Continuous-coverage and/or stacjed SPBs retain properties (e.,g. fluidity) more similar to native biological membranes, which is desirable for most applications. Using neutron reflectivity, we examined face coverage and potential stacking of dipalmitoylphosphatidylcholine (DPPC) bilayers on the (1120) face of sapphire (a-Al2O3). Nearly full bilayers were formed at low to neutral pH, when the sapphire surface is positively charged, and at low ionic strength (l=15 mM NaCl). Coverage decreased at higher pH, close to the isoelectric point of sapphire, and also at high I>210mM, or with addition of 2mM Ca2+. The latter two effects are additive, suggesting that Ca2+ mitigates the effect of higher I. These trends agree with previous results for phospholipid adsorption on a-Al2O3 particles determined by adsorption isotherms and on single-crystal (1010) sapphire by atomic force microscopy, suggesting consistency of oxide surface chemistry-dependent effects across experimental techniques.

  7. Growth and characterisation of epitaxially ordered zinc aluminate domains on c-sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Grabowska, J.; Rajendra Kumar, R.T. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland); McGlynn, E. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland)], E-mail: enda.mcglynn@dcu.ie; Nanda, K.K. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland); Newcomb, S.B. [Glebe Scientific Ltd., Newport, Co. Tipperary (Ireland); McNally, P.J.; O' Reilly, L. [School of Electronic Engineering/Research Institute for Networks and Communications Engineering, Dublin City University (Ireland); Mosnier, J.-P.; Henry, M.O. [School of Physical Sciences/National Centre for Plasma Science and Technology, Dublin City University (Ireland)

    2008-02-29

    Epitaxially ordered zinc aluminate domains with sub-micron dimensions are formed on bare c-sapphire substrates using a vapour phase method (with vapour generated by carbothermal reduction of ZnO) at various temperatures and growth durations. A zinc aluminate (ZnAl{sub 2}O{sub 4}) layer is formed by reaction of the source materials (Zn and O) with the substrate. We observe crystallites with a well-defined epitaxial relationship on the sapphire substrate in addition to polycrystalline material. The epitaxially oriented deposit displays the form of characteristically twinned (singly or multiply) grains of sub-micron dimensions with three variants, consistent with the c-sapphire substrate symmetry. Scanning electron microscopy and transmission electron microscopy studies show that the formation of these grains is associated with the presence of extended defects in the sapphire substrate. Epitaxially ordered grains formed at higher temperatures show a change in the nature of the twin boundaries and epitaxial relations as a function of growth time, attributed to the effects of annealing during growth.

  8. Multiphoton imaging with a novel compact diode-pumped Ti:sapphire oscillator

    DEFF Research Database (Denmark)

    König, Karsten; Andersen, Peter E.; Le, Tuan;

    2015-01-01

    Multiphoton laser scanning microscopy commonly relies on bulky and expensive femtosecond lasers. We integrated a novel minimal-footprint Ti:sapphire oscillator, pumped by a frequency-doubled distributed Bragg reflector tapered diode laser, into a clinical multiphoton tomograph and evaluated its...

  9. New sapphire and ruby components and their manufacture using diamond abrasives

    Science.gov (United States)

    Sauser, D.

    The properties of synthetic aluminum oxides (sapphire and ruby) and their applications in watchmaking (watch bearings and watchglasses) and as hard-wearing components such as centering devices for optical fibres and water jet nozzles for material cutting are discussed. Examples are given of the use of diamonds tools for machining such components, including sawing, drilling, grinding and polishing operations.

  10. Vanadium-rich ruby and sapphire within Mogok Gemfield, Myanmar: implications for gem color and genesis

    Science.gov (United States)

    Zaw, Khin; Sutherland, Lin; Yui, Tzen-Fu; Meffre, Sebastien; Thu, Kyaw

    2015-01-01

    Rubies and sapphires are of both scientific and commercial interest. These gemstones are corundum colored by transition elements within the alumina crystal lattice: Cr3+ yields red in ruby and Fe2+, Fe3+, and Ti4+ ionic interactions color sapphires. A minor ion, V3+ induces slate to purple colors and color change in some sapphires, but its role in coloring rubies remains enigmatic. Trace element and oxygen isotope composition provide genetic signatures for natural corundum and assist geographic typing. Here, we show that V can dominate chromophore contents in Mogok ruby suites. This raises implications for their color quality, enhancement treatments, geographic origin, exploration and exploitation and their comparison with rubies elsewhere. Precise LA-ICP-MS analysis of ruby and sapphire from Mogok placer and in situ deposits reveal that V can exceed 5,000 ppm, giving V/Cr, V/Fe and V/Ti ratios up to 26, 78, and 97 respectively. Such values significantly exceed those found elsewhere suggesting a localized geological control on V-rich ruby distribution. Our results demonstrate that detailed geochemical studies of ruby suites reveal that V is a potential ruby tracer, encourage comparisons of V/Cr-variation between ruby suites and widen the scope for geographic typing and genesis of ruby. This will allow more precise comparison of Asian and other ruby fields and assist confirmation of Mogok sources for rubies in historical and contemporary gems and jewelry.

  11. "You Hafta Push": Using Sapphire's Novel to Teach Introduction to American Government

    Science.gov (United States)

    Pappas, Christine

    2007-01-01

    Using fiction in the classroom can dramatize public policy issues and political science concepts, therefore, making them more real and relevant to students. Sapphire's 1996 novel "Push" puts a face on welfare, rape, incest, child abuse, educational inequalities, homophobia, and AIDS. I also use this novel to discuss the public policy process,…

  12. Thermal Stresses and Cracks During the Growth of Large-sized Sapphire with SAPMAC Method

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The finite-element method has been used to study the thermal stress distribution in large-sized sapphire crystals grown with the sapphire growth technique with micro-pulling and shoulder-expanding at cooled center (SAPMAC) method. A critical defect model has been established to explain the growth and propagation of cracks during the sapphire growing process. It is demonstrated that the stress field depends on the growth rate, the ambient temperature and the crystallizing direction. High stresses always exist near the growth interfaces, at the shoulder-expanding locations, the tailing locations and the sites where the diameters undergo sharp changes. The maximum stresses always occur at the interface of seeds and crystals. Cracks often form in the critical defect region and spread in the m-planes and a-planes under applied tensile stresses during crystal growth. The experimental results have verified that with the improved system of crystal growth and well-controlled techniques, the large-sized sapphire crystals of high quality can be grown due to absence of cracks.

  13. A century of sapphire crystal growth: origin of the EFG method

    Science.gov (United States)

    Harris, Daniel C.

    2009-08-01

    A. Verneuil developed flame fusion to grow sapphire and ruby on a commercial scale around 1890. Flame fusion was further perfected by Popov in the Soviet Union in the 1930s and by Linde Air Products Co. in the U.S. during World War II. Union Carbide Corp., the successor to Linde, developed Czochralski crystal growth for sapphire laser materials in the 1960s. Edge-Defined Film-Fed Growth (EFG) was invented by H. Labelle in the 1960s and the Heat Exchanger Method (HEM) was invented by F. Schmid and D. Viechnicki in 1967. Both methods were commercialized in the 1970s. Gradient solidification was invented in Israel in the 1970s by J. Makovsky. The Horizontal Directional Solidification Method (HDSM) was invented by Kh. S. Bagdasorov in the Soviet Union in the 1960s. Kyropoulos growth of sapphire, known as GOI crystal growth in the Soviet Union, was developed by M. Musatov at the State Optical Institute in St. Petersburg in the 1970s. Today, half of the world's sapphire is produced by the GOI method.

  14. PHYTOSSOCIOLOGY AND DIAMETRIC ESTRUCTURE IN THE GALLERY FOREST OF PITOCO, IN THE ECOLOGICAL RESERVE OF IBGE, DF

    Directory of Open Access Journals (Sweden)

    Manoel Cláudio da Silva Júnior

    2005-06-01

    Full Text Available The gallery forest, in the cerrado region, has a very important function on the environmental and social equilibrium.Despite been protected by law, gallery forests have been systematically replaced by agriculture and other regional uses. One thousandtrees (DAP 5cm were sampled using point centered-quarter (PCQ method. Sampling lines were established, from the head to themouth of the stream and from the stream margins to the forest-cerrado border, of the Pitoco gallery forest, in the IBGE EcologicalReserve, in Federal District, Brazil. Results showed 99 species of 46 families in the area. The most important families were:Leguminosae, Vochysiaceae, Rubiaceae, Anacardiaceae, Euphorbiaceae, Lauraceae, Burseraceae, Moraceae, Annonaceae eSymplocaceae, while the most important species were: Callisthene major, Tapirira guianensis, Protium almecega, Copaifera langsdorffii,Sclerolobium paniculatum var. rubiginosum, Pseudolmedia guaranítica, Faramea cyanea, Emmotum nitens, Lamanonia ternata,Maprounea guianensis, excluding the group of dead trees which was ranked in the 5th position. Density and basal area were estimatedas 1971 trees.ha-1 and 38,8 m².ha-1 ,respectively. Diameter distribution showed a tendency to an inverted J curve revealing low levelsof disturbance in this gallery forest. A floristic comparison carried out with 21 gallery forests in the Federal District indicated Pitocogallery forest as a rich site including 99 (26,2% of the total of 378 species recorded, a Shannon & Weaver diversity index estimatedas 3,86 nats.ind-1 and Sørensen similarities ranging from 0,29 to 0,80 with DF gallery forests.

  15. Philadelphia's Gallery II shopping center complex: an analysis for the application of an integrated community energy system. Vol. 2: complete data report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, C.; Davis, A.; Kron, R.

    1979-11-01

    Detailed findings and calculations of Argonne's study of energy systems for the Gallery II commercial complex in Philadelphia are presented. The presentation includes design demands, service demand profiles, and descriptions of the seven alternative energy systems considered for Gallery II. The energy system descriptions include schematics, equipment used, energy-use calculations, equipment costs, operation and maintenance costs, and energy costs.

  16. Telerobotic Haptic Exploration in Art Galleries and Museums for Individuals with Visual Impairments.

    Science.gov (United States)

    Park, Chung Hyuk; Ryu, Eun-Seok; Howard, Ayanna M

    2015-01-01

    This paper presents a haptic telepresence system that enables visually impaired users to explore locations with rich visual observation such as art galleries and museums by using a telepresence robot, a RGB-D sensor (color and depth camera), and a haptic interface. The recent improvement on RGB-D sensors has enabled real-time access to 3D spatial information in the form of point clouds. However, the real-time representation of this data in the form of tangible haptic experience has not been challenged enough, especially in the case of telepresence for individuals with visual impairments. Thus, the proposed system addresses the real-time haptic exploration of remote 3D information through video encoding and real-time 3D haptic rendering of the remote real-world environment. This paper investigates two scenarios in haptic telepresence, i.e., mobile navigation and object exploration in a remote environment. Participants with and without visual impairments participated in our experiments based on the two scenarios, and the system performance was validated. In conclusion, the proposed framework provides a new methodology of haptic telepresence for individuals with visual impairments by providing an enhanced interactive experience where they can remotely access public places (art galleries and museums) with the aid of haptic modality and robotic telepresence.

  17. Mycelial carton galleries of Azteca brevis (Formicidae) as a multi-species network

    Science.gov (United States)

    Mayer, Veronika E.; Voglmayr, Hermann

    2009-01-01

    Apart from growing fungi for nutrition, as seen in the New World Attini, ants cultivate fungi for reinforcement of the walls of their nests or tunnel-shaped runway galleries. These fungi are grown on organic material such as bark, epiphylls or trichomes, and form stable ‘carton structures’. In this study, the carton of the runway galleries built by Azteca brevis (Formicidae, Dolichoderinae) on branches of Tetrathylacium macrophyllum (Flacourtiaceae) is investigated. For the first time, molecular tools are used to address the biodiversity and phylogenetic affinities of fungi involved in tropical ant carton architecture, a previously neglected ant–fungus mutualism. The A. brevis carton involves a complex association of several fungi. All the isolated fungi were unequivocally placed within the Chaetothyriales by DNA sequence data. Whereas five types of fungal hyphae were morphologically distinguishable, our DNA data showed that more species are involved, applying a phylogenetic species concept based on DNA phylogenies and hyphal morphology. In contrast to the New World Attini with their many-to-one (different ant species—one fungal cultivar) pattern, and temperate Lasius with a one-to-two (one ant species—two mutualists) or many-to-one (different ant species share the same mutualist) system, the A. brevis–fungi association is a one-to-many multi-species network. Vertical fungus transmission has not yet been found, indicating that the A. brevis–fungi interaction is rather generalized. PMID:19556257

  18. Shielding design of the linear accelerator at RAON: Accelerator tunnel and utility gallery

    Science.gov (United States)

    Kim, Suna; Kang, Bo Sun; Lee, Sangjin; Nam, Shinwoo; Chung, Yeonsei

    2015-10-01

    RAON is the first Korean heavy-ion accelerator for various rare-isotope experiments and will be constructed by the year of 2021. The building for the about 550-m-long superconducting linear accelerator at RAON has three divisions in the vertical layout: accelerator tunnel, intermediate tunnel, and utility gallery. One of the requirements for the building design is that the effective dose rate in the utility gallery should be well below the dose limit for workers. Other parts of the building underground are classified as high-radiation zones where access is strictly controlled. The radiation dose distribution in the building has been calculated by using the Monte Carlo transport code MCNPX including the radiation streaming effects through the intermediate tunnel and penetrating holes. We have applied a point beam loss model in which the continuous beam loss along the beam line is treated as an equivalent point loss with a simple target. We describe the details of the calculation and discuss the results.

  19. The BOSS Emission-Line Lens Survey. IV. : Smooth Lens Models for the BELLS GALLERY Sample

    CERN Document Server

    Shu, Yiping; Mao, Shude; Kochanek, Christopher S; Pérez-Fournon, Ismael; Oguri, Masamune; Montero-Dorta, Antonio D; Cornachione, Matthew A; Marques-Chaves, Rui; Zheng, Zheng; Brownstein, Joel R; Ménard, Brice

    2016-01-01

    We present \\textsl{Hubble Space Telescope} (\\textsl{HST}) F606W-band imaging observations of 21 galaxy-Ly$\\alpha$ emitter lens candidates in the Baryon Oscillation Spectroscopic Survey (BOSS) Emission-Line Lens Survey (BELLS) for GALaxy-Ly$\\alpha$ EmitteR sYstems (BELLS GALLERY) survey. 17 systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately $0.55$, while the lensed sources are Ly$\\alpha$ emitters (LAEs) at redshifts from 2 to 3. Although the \\textsl{HST} imaging data are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are on average $60\\%$ larger than those of the BELLS lenses because of the much higher source redshifts which will allow a detailed investigation of the radius evolution of the mass profile...

  20. Improvement of luminous intensity of InGaN light emitting diodes grown on hemispherical patterned sapphire

    Science.gov (United States)

    Lee, Jae-Hoon; Oh, Jeong-Tak; Park, Jin-Sub; Kim, Je-Won; Kim, Yong-Chun; Lee, Jeong-Wook; Cho, Hyung-Koun

    2006-06-01

    To improve the external quantum efficiency, high quality GaN film was grown on hemispherical patterned sapphire by controlling the V/III ratio during the initial growth stage. The luminous intensity of white flash light emitting diode (LED) grown on hemispherical patterned sapphire (HPS) was estinated to be 5.8 cd at a forward current of 150 mA, which is improved by 20% more than that of LED grown on conventional sapphire substrate. The improvement of luminous intensity was explained by considering not only an increase of the extraction efficiency via the suppressed total internal reflection at the corrugated interface but also a decrease of dislocation density.

  1. Adult Education for Social and Environmental Change in Contemporary Public Art Galleries and Museums in Canada, Scotland and England

    Science.gov (United States)

    Clover, Darlene E.

    2015-01-01

    Historically, pubic art galleries and museums have a well-deserved reputation for elitism, colonialism and exclusion and they are, therefore, frequently omitted from the discourse of adult education. However, the escalating social, cultural and ecological problems of this new century have placed pressure on these public institutions to change and…

  2. Social Phenomenological Analysis as a Research Method in Art Education: Developing an Empirical Model for Understanding Gallery Talks

    Science.gov (United States)

    Hofmann, Fabian

    2016-01-01

    Social phenomenological analysis is presented as a research method to study gallery talks or guided tours in art museums. The research method is based on the philosophical considerations of Edmund Husserl and sociological/social science concepts put forward by Max Weber and Alfred Schuetz. Its starting point is the everyday lifeworld; the…

  3. 加拿大阿尔伯塔省艺术博物馆%Art Gallery of Alberta

    Institute of Scientific and Technical Information of China (English)

    美国兰德尔·斯图特建筑事务所

    2007-01-01

    @@ The new Art Gallery of Alberta was conceived as an engaging and stimulating center for contemporary art in Edmonton. Celebrating its prominent location on Sir Winston Churchill Square,the main civic and arts public square in the city,the project represents the museum's commitment to enhancing the public's experience of the visual arts.

  4. Rael Artel Gallery: Non-Profit Project Space : short tale of an experimental project's space tactics / Kiwa

    Index Scriptorium Estoniae

    Kiwa, pseud., 1975-

    2009-01-01

    Aastatel 2004-2008 Pärnus ja aastatel 2006-2008 Tartus tegutsenud Rael Artel Galeriist, mille looja ja moderaator oli Rael Artel. Galerii tegevus lõppes kunstialbumi "Hotell Pärnu : Rael Arel Gallery : Non Profit Project Space 2004-2008 / kontseptsioon ja toimetamine: Rael Artel" ilmumisega 2009. aastal

  5. Stories from History, Myth, and the Bible. Snite Museum of Art Gallery Guide. Parts 1-3.

    Science.gov (United States)

    Matthias, Diana C. J.; Barrett, Jesse

    This art education resource, designed for use in the Snite Museum of Art, may also be used with slides or reproductions. Black and white reproductions are included for each of the art works represented, along with title, artist, date, and media information. This three part gallery guide presents a brief synopsis of the stories narrated in the…

  6. Beyond the Gallery: Interactions between Audiences, Artists, and Their Art through the Kampala Art Tour 2007-2010

    Science.gov (United States)

    Nagawa, Margaret

    2012-01-01

    When one walks into an art gallery in Kampala, the capital city of Uganda, one sees a predominantly non-Ugandan audience. Visitors to homes of Ugandans, even those wealthy enough to afford art, find typically bare walls. This begs broader questions: (1) What is it about the education and presentation of contemporary art that excludes local…

  7. Beyond the Gallery: Interactions between Audiences, Artists, and Their Art through the Kampala Art Tour 2007-2010

    Science.gov (United States)

    Nagawa, Margaret

    2012-01-01

    When one walks into an art gallery in Kampala, the capital city of Uganda, one sees a predominantly non-Ugandan audience. Visitors to homes of Ugandans, even those wealthy enough to afford art, find typically bare walls. This begs broader questions: (1) What is it about the education and presentation of contemporary art that excludes local…

  8. Reporting on What Jane Saw 2.0: Female Celebrity and Sensationalism in Boydell’s Shakespeare Gallery

    Directory of Open Access Journals (Sweden)

    Janine Barchas

    2015-03-01

    Full Text Available This essay reports on ongoing efforts to build an accurate digital model of John Boydell’s popular Shakespeare Gallery precisely as it looked in August 1796—when a 20-year-old Jane Austen visited London’s sites, staying within a ten-minute walk from the gallery. The essay argues for the substantial difference between studying Boydell’s pictures in a paper volume (whether as lists, illustrations in books, or engraved folio plates and viewing them as an exhibition of paintings on walls, albeit virtual ones. For example, the digital reconstruction illuminated commissions from several female participants in Boydell’s male-dominated gallery, especially Angelica Kauffman (1741-1807 and Anne Seymour Damer (1749-1828. In addition, the essay also recounts how the celebrity of model Emma Hart/Hamilton (1765-1815 safeguarded one Boydell painting from oblivion while The Shakespeare Gallery proved the site of a strange form of self-promotion practiced by actress Mary Wells (1762-1829. Our digital visualization of an historic exhibition in 1796 brought the controversial celebrity of a few women artists into focus. In sum, this essay shows DH methodology in action while sampling what might be gleaned when digital tools serve historical scholarship in the humanities.

  9. Rael Artel Gallery: Non-Profit Project Space : short tale of an experimental project's space tactics / Kiwa

    Index Scriptorium Estoniae

    Kiwa, pseud., 1975-

    2009-01-01

    Aastatel 2004-2008 Pärnus ja aastatel 2006-2008 Tartus tegutsenud Rael Artel Galeriist, mille looja ja moderaator oli Rael Artel. Galerii tegevus lõppes kunstialbumi "Hotell Pärnu : Rael Arel Gallery : Non Profit Project Space 2004-2008 / kontseptsioon ja toimetamine: Rael Artel" ilmumisega 2009. aastal

  10. Achieving strong doubling power by optical phase-locked Ti:sapphire laser and MOPA system

    Institute of Scientific and Technical Information of China (English)

    Yu Peng; Baike Lin; Qiang Wang; Yang Zhao; Ye Li; Jianping Cao; Zhanjun Fang; Erjun Zang

    2012-01-01

    We show two external cavity-enhanced second-harmonic generations of 922 nm with periodically poled potassium titanyl phosphate crystal,whose doubling cavities are locked separately with Hansch-Couillaud and intra-modulation methods.The outputs of second-harmonic generation reach 310 mW,54.8% of the conversion efficiency from the Ti;sapphire laser with the crystal length of 10 mm,and 208 mW,59% of the conversion efficiency from the MOPA system with the crystal length of 30 mm.It consists of heterodyning the Ti;sapphire laser and the MOPA system,and compares the phase of the beat frequency signal with the phase of a reference RF local oscillator.The resulting phase error is used as a feedback signal and fed back to the reference cavity of the Ti;sapphire laser to lock the two lasers in phase.A stable blue power of 520 mW is obtained,which supplies enough power for the cooling and trapping step of the strontium (Sr) optical lattice clock.Four stable isotopes of Sr,84Sr,86Sr,87Sr,and 88Sr,are detected by probing the laser during a strong 460.7-nm cycling transition (5s21S0-5s5p1P1).%We show two external cavity-enhanced second-harmonic generations of 922 nm with periodically poled potassium titanyl phosphate crystal, whose doubling cavities are locked separately with Hansch-Couillaud and intra-modulation methods. The outputs of second-harmonic generation reach 310 mW, 54.8% of the conversion efficiency from the Ti:sapphire laser with the crystal length of 10 mm, and 208 mW, 59% of the conversion efficiency from the MOPA system with the crystal length of 30 mm. It consists of heterodyning the Ti:sapphire laser and the MOPA system, and compares the phase of the beat frequency signal with the phase of a reference RF local oscillator. The resulting phase error is used as a feedback signal and fed back to the reference cavity of the Ti:sapphire laser to lock the two lasers in phase. A stable blue power of 520 mW is obtained, which supplies enough power for the cooling

  11. Reduction of Residual Stresses in Sapphire Cover Glass Induced by Mechanical Polishing and Laser Chamfering Through Etching

    Directory of Open Access Journals (Sweden)

    Shih-Jeh Wu

    2016-10-01

    Full Text Available Sapphire is a hard and anti-scratch material commonly used as cover glass of mobile devices such as watches and mobile phones. A mechanical polishing using diamond slurry is usually necessary to create mirror surface. Additional chamfering at the edge is sometimes needed by mechanical grinding. These processes induce residual stresses and the mechanical strength of the sapphire work piece is impaired. In this study wet etching by phosphate acid process is applied to relief the induced stress in a 1” diameter sapphire cover glass. The sapphire is polished before the edge is chamfered by a picosecond laser. Residual stresses are measured by laser curvature method at different stages of machining. The results show that the wet etching process effectively relief the stress and the laser machining does not incur serious residual stress.

  12. Abundance and frugivory of the toco toucan (Ramphastos toco in a gallery forest in Brazil's Southern Pantanal

    Directory of Open Access Journals (Sweden)

    J. Ragusa-Netto

    Full Text Available Unlike other toucan species, the Toco toucan (Ramphastos toco - the largest Ramphastidae - usually inhabits dry semi-open areas. This conspicuous canopy frugivore uses a large home range that includes a variety of vegetation types, among which gallery forests are widely cited as important to this species. However, the factors relating to the occurrence of Toco toucans in such habitats are unclear. I studied the abundance of Toco toucans as well as the availability of fleshy fruit in a gallery forest in the southern Pantanal (sub-region of Miranda, Brazil, in order to assess the relationship between these parameters. Also, I examined toucan foraging activity to analyze its relationship with both toucan abundance and fruit availability. The presence of the Toco toucan was more common in the gallery forest from the middle to the end of the dry season and during the middle of the wet season. Toucans foraged for fleshy fruits, mainly Genipa americana, Ficus luschnatiana, and Cecropia pachystachya fruits, feeding mostly on G. americana (by far the favorite food resource and F. luschnatiana fruits during the dry season, while C. pachystachya fruits were important in the wet season. Toco toucans foraged particularly heavily (> 80% of foraging activity on G. americana fruits during the latter part of the dry season, when fleshy fruit availability declined sharply. Toco toucan abundance in the gallery forest was associated with the availability of the most commonly consumed fleshy fruits, and also with its foraging activity. This finding suggests that the Toco toucan moved to the gallery forest periodically in response to the availability of abundant food resources, especially the G. americana fruits widely available and exploited during the severely dry season. Therefore, these fruits potentially contribute to Toco toucan persistence in the South Pantanal during the harshest period of the year.

  13. Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil).

    Science.gov (United States)

    Ragusa-Netto, J

    2015-01-01

    Cracids are generalist frugivores, which often exploit plant food resources such as flowers and leaves, mainly when fruit production declines. The Chaco chachalaca (Ortalis canicollis) is the most abundant cracid in the Pantanal (Brazil), and particularly common in the gallery forests. However, the factors related to their occurrence in this habitat type are unclear. In this study I describe the feeding habits and feeding niche breadth fluctuations of the Chaco chachalaca in relation to food resources abundance and diversity at the Miranda river gallery forest (Southern Pantanal). I also analyzed the relationships between Chaco chachalacas feeding activity and food resources abundance. This parameter (flowers and fruits) exhibited significant seasonal differences of abundance in which flowers were plentiful at the end of the dry, while fruits were abundant during the early wet season. However, food resources diversity to Chaco chachalacas exhibited no seasonal difference. Their feeding activity paralleled the availability of food resources, so that when some items were massively available an enhanced number of Chaco chachalacas foraged in the gallery forest, particularly during the prolonged dry season when they extensively used flowers and Genipa americana fruits. In fact, the Chaco chachalaca feeding niche breadth value presented low values in this period, while high values were common in the rest of the year. The flexible diet of this cracid, potentially favors their year round presence in the gallery forest, mainly during the prolonged dry season when the propensity for famine might be high. Since the Chaco chachalaca is among the largest and most abundant canopy frugivores in the gallery forest, it may contribute to forest regeneration, an underscored role due to the impact of annual floods and meandering dynamics on tree loss.

  14. Erbium-doped crystalline YAG planar and ridge waveguides on quartz and sapphire substrates: deposition and material characterisation

    Science.gov (United States)

    Facchini, G.; Zappettini, A.; Canali, A.; Martinelli, M.; Gabetta, G.; Tallarida, G.

    2001-06-01

    Er-doped Yttrium-Aluminium-Garnet (YAG) planar and ridge waveguides have been grown on quartz and sapphire substrates. The waveguides have been structurally, morphologically and stoichiometrically characterised by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. Doping concentrations up to 5% have been successfully demonstrated. Deposition of channel waveguide on sapphire substrate results in a correct ridge shape.

  15. Evaluation of the Quality of Sapphire Using X-Ray Rocking Curves and Double-Crystal X-Ray Topography

    Science.gov (United States)

    1994-05-01

    hard, high-strength, chemically resistant optical windows; and sub- srates for the growth of epitaxial films. The quality of a sapphire crystal can... crystal diffractometer. Single- crystal sapphire may be grown by a variety of different methods, of which the more common are Verneuil (flame fusion...Linear features (L), which may represent slight variations in lattice parameter along the crystal growth front, or dislocation networks, ad small

  16. Diversity and Structure of the Gama Gallery Forest in Central Brazil in 2009

    Directory of Open Access Journals (Sweden)

    Roberto Tramontina Araujo

    2016-06-01

    Full Text Available The objective of this study was to evaluate the diversity and structure of the tree community of the Gama gallery forest, in the Federal District, in 2009. A total of 151 permanent plots of 10×20 m were allocated continually along ten lines perpendicular to the watercourse. All individuals with diameter at breast height (DBH equal or greater than 10 cm were tagged and measured. In total, 114 species in 52 families and 96 genera were identified. The density was 643 ind.ha-1, the basal area was 31.52 m2.ha-1 and 13 species were frequently at least in 25% of the plots. The Shannon index was 3.91 nats.ind-1 and the Pielou index was 82%, expressing the good conservation condition and the high diversity of the vegetation. The diameter distribution curve showed an "inverted J" pattern.

  17. PENINGKATAN AKTIVITAS DAN HASIL BELAJAR AKUNTANSI MATERI LAPORAN KEUANGAN MELALUI METODE GALLERY WALK DUATI-DUATA

    Directory of Open Access Journals (Sweden)

    Nining Mariyaningsih

    2014-06-01

    Full Text Available In learning accounting, conventional learning models are still frequently used by the teacher. As a result, the learning become monotonous and it’s not maximum. The problem of this study is wheather through Gallery Walk Duati-Duata can improve the activity and learning outcomes of accounting students.This study was class action research which was designed into two main cycles. Each cycle consisted of four stages started from planning, acting, observing and reflecting. The result showed that : (1 Learning activities increase from 27,78% before cycle, 69,45% in first cycle and 93,88% in second cycle, (2 The learning outcomes increase, from 22,22% before siklus, 75% in first cycle and 94,44% in second cycle. Therefore the use of this methods could be one of the reference of teachers in implementing the learning process.

  18. Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery : [luuletused] / Artur Alliksaar

    Index Scriptorium Estoniae

    Alliksaar, Artur, 1923-1966

    2001-01-01

    Tekst eesti ja inglise k. A. Alliksaare lühibiograafia eesti ja inglise k. lk. 55. Sisu: Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery ; "Olen määratusuur mets..." = "I am infinitely vast forest..." ; "Olen koredate külgedega kalju..." = "I am rough-sided cliff..." ; "Olen meri, millel puudub äär..." = "I am sea that knows no bounds..." ; "Liikumine on niivõrd liitunud mu loomusega..." = "Movement is so much part of me..." ; "Ma ei söandaks öelda, et olen rikas..." = "I would not claim that I am rich..." ; Pöördehetk = Turning point ; Kuigi on nii palju lilli... = Though there are so many flowers ; Antidolorosum

  19. 3-D density imaging with muon flux measurements from underground galleries

    Science.gov (United States)

    Lesparre, N.; Cabrera, J.; Marteau, J.

    2017-03-01

    Atmospheric muon flux measurements provide information on subsurface density distribution. In this study, muon flux was measured underground, in the Tournemire experimental platform (France). The objective was to image the medium between the galleries and the surface and evaluate the feasibility to detect the presence of discontinuities, for example, produced by secondary subvertical faults or by karstic networks. Measurements were performed from three different sites with a partial overlap of muon trajectories, offering the possibility to seek density variations at different depths. The conversion of the measured muon flux to average density values showed global variations further analysed through a 3-D nonlinear inversion procedure. Main results are the presence of a very low density region at the level of the upper aquifer, compatible with the presence of a karstic network hosting local cavities, and the absence of secondary faults. We discuss the validity of the present results and propose different strategies to improve the accuracy of such measurements and analysis.

  20. PENINGKATAN AKTIVITAS DAN HASIL BELAJAR AKUNTANSI MATERI LAPORAN KEUANGAN MELALUI METODE GALLERY WALK DUATI-DUATA

    Directory of Open Access Journals (Sweden)

    Nining Mariyaningsih

    2015-03-01

    Full Text Available In learning accounting, conventional learning models are still frequently used by the teacher. As a result, the learning become monotonous and it’s not maximum. The problem of this study is wheather through Gallery Walk Duati-Duata can improve the activity and learning outcomes of accounting students.This study was class action research which was designed into two main cycles. Each cycle consisted of four stages started from planning, acting, observing and reflecting. The result showed that : (1 Learning activities increase from 27,78% before cycle, 69,45% in first cycle and 93,88% in second cycle, (2 The learning outcomes increase, from 22,22% before siklus, 75% in first cycle and 94,44% in second cycle. Therefore the use of this methods could be one of the reference of teachers in implementing the learning process.

  1. Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery : [luuletused] / Artur Alliksaar

    Index Scriptorium Estoniae

    Alliksaar, Artur, 1923-1966

    2001-01-01

    Tekst eesti ja inglise k. A. Alliksaare lühibiograafia eesti ja inglise k. lk. 55. Sisu: Tikutõmbeid kottpimedas galeriis = Striking matches in a pitch-dark gallery ; "Olen määratusuur mets..." = "I am infinitely vast forest..." ; "Olen koredate külgedega kalju..." = "I am rough-sided cliff..." ; "Olen meri, millel puudub äär..." = "I am sea that knows no bounds..." ; "Liikumine on niivõrd liitunud mu loomusega..." = "Movement is so much part of me..." ; "Ma ei söandaks öelda, et olen rikas..." = "I would not claim that I am rich..." ; Pöördehetk = Turning point ; Kuigi on nii palju lilli... = Though there are so many flowers ; Antidolorosum

  2. Analysis of borehole expansion and gallery tests in anisotropic rock masses

    Science.gov (United States)

    Amadei, B.; Savage, W.Z.

    1991-01-01

    Closed-form solutions are used to show how rock anisotropy affects the variation of the modulus of deformation around the walls of a hole in which expansion tests are conducted. These tests include dilatometer and NX-jack tests in boreholes and gallery tests in tunnels. The effects of rock anisotropy on the modulus of deformation are shown for transversely isotropic and regularly jointed rock masses with planes of transverse isotropy or joint planes parallel or normal to the hole longitudinal axis for plane strain or plane stress condition. The closed-form solutions can also be used when determining the elastic properties of anisotropic rock masses (intact or regularly jointed) in situ. ?? 1991.

  3. An Allergen Portrait Gallery: Representative Structures and an Overview of IgE Binding Surfaces

    Directory of Open Access Journals (Sweden)

    Ovidiu Ivanciuc

    2010-10-01

    Full Text Available Recent progress in the biochemical classification and structural determination of allergens and allergen–antibody complexes has enhanced our understanding of the molecular determinants of allergenicity. Databases of allergens and their epitopes have facilitated the clustering of allergens according to their sequences and, more recently, their structures. Groups of similar sequences are identified for allergenic proteins from diverse sources, and all allergens are classified into a limited number of protein structural families. A gallery of experimental structures selected from the protein classes with the largest number of allergens demonstrate the structural diversity of the allergen universe. Further comparison of these structures and identification of areas that are different from innocuous proteins within the same protein family can be used to identify features specific to known allergens. Experimental and computational results related to the determination of IgE binding surfaces and methods to define allergen-specific motifs are highlighted.

  4. Strike-slip faults imaging from galleries with seismic waveform imaging methods

    Science.gov (United States)

    Bretaudeau, F.; Gélis, C.; Leparoux, D.; Cabrera, J.; Côte, P.

    2011-12-01

    Deep argillaceous formations are potential host media for radioactive waste due to their physical properties such as low intrinsic permeability and radionuclide retention (Boisson et al 2001). The experimental station of Tournemire is composed of an old tunnel excavated in 1885 in a 250m thick Toarcien argilitte layer, and of several galleries excavated more recently in directions perpendicular and parallel to the tunnel. This station is operated by the French Institute for Radiological protection and Nuclear Safety (IRSN) in order to expertise possible projects of radioactive waste disposal in a geological clay formation. The presence of secondary strike-slip faults in argillaceous formations must be well assessed since they could change any rock properties such as permeability. The ones with small vertical offsets as observed in the station cannot be seen from the surface, indeed we investigate on new approaches to image them directly from the underground works. We investigate here on the potential of new imaging methods that take advantage of the full seismic waveforms in order to optimise the imaging performances: Full Waveform Inversion (FWI) and Reverse Time Migration (RTM). We try to assess the capacities and limits of those methods in this specific context, and to determine the optimum acquisition and processing parameters. The subvertical fault in the nearly homogeneous subhorizontal structure of the clay layer allows us to consider a 2D imaging problem with no anisotropy where the fault is surrounded by three galleries. The waveform inversion strategy used is based on the frequency domain formulation proposed by Pratt et al. (1990). Non linearity is mitigated by introducing sequentially information from 50Hz to 1000Hz and starting from an homogeneous medium as initial model. Preliminary tests on synthetic data (fig. 1) show the ability of FWI to quantitatively image the fault zone and illustrate the impact of the illumniation configuration. RTM suceeds to

  5. Formation of silicon nanocrystals in sapphire by ion implantation and the origin of visible photoluminescence

    Science.gov (United States)

    Yerci, S.; Serincan, U.; Dogan, I.; Tokay, S.; Genisel, M.; Aydinli, A.; Turan, R.

    2006-10-01

    Silicon nanocrystals, average sizes ranging between 3 and 7nm, were formed in sapphire matrix by ion implantation and subsequent annealing. Evolution of the nanocrystals was detected by Raman spectroscopy and x-ray diffraction (XRD). Raman spectra display that clusters in the matrix start to form nanocrystalline structures at annealing temperatures as low as 800°C in samples with high dose Si implantation. The onset temperature of crystallization increases with decreasing dose. Raman spectroscopy and XRD reveal gradual transformation of Si clusters into crystalline form. Visible photoluminescence band appears following implantation and its intensity increases with subsequent annealing process. While the center of the peak does not shift, the intensity of the peak decreases with increasing dose. The origin of the observed photoluminescence is discussed in terms of radiation induced defects in the sapphire matrix.

  6. Process for the Φ130 sapphire window element with long distance and high resolution

    Science.gov (United States)

    Xu, Zengqi; Su, Ying; Lei, Jianli; Guo, Rui; Zhang, Feng; Guo, Xinlong; Liu, Xuanmin; Sun, Taohui

    2016-10-01

    With the process test for the choice of materials, the test materials and the molds, the abrasives, the temperature and the different machining process monitoring parameters of the polishing machine, the process method and the quality control technology were figured out for the Φ130 sapphire window element with long distance and high resolution (hereinafter referred to as window element), meantime, the optimum process condition was determined to machine the element. The results were that the high resolution imaging window was processed with the surface roughness Ra of 0.639nm, the transmission distortion of λ/10 (λ=632.8nm), the parallel error of 5″, the resolution of 1.47″ and the focal length of 5 km, which can satisfy the imaging requirements better for the military photoelectric device for sapphire window with long distance and high resolution.

  7. Growth and Characterization of InN Thin Films on Sapphire by MOCVD

    Institute of Scientific and Technical Information of China (English)

    XIE Zi-Li; ZHANG Rong; XIU Xiang-Qian; LIU Bin; LI Liang; HAN Ping; GU Shu-Lin; SHI Yi; ZHENG You-Dou

    2007-01-01

    Indium nitride thin films are grown on sapphire substrates by metal-organic chemical vapour deposition(MOCVD).By employing three-step layer buffers,the mirror-like layers on two-inch sapphire wafers have been obtained.The structural,optical and electrical characteristics of InN are investigated by x-ray diffraction,scanning electron microscopy,atomic force microscopy,photoluminescence and infrared optical absorpton.The photoluminescence and the absorption studies of the materials reveal a marked energy bandgap structure around 0.70 eV at room temperature.The room-temperature Hall mobility and carrier concentration of the film are typically 939 cm2/Vs,and 3.9×1018cm-3,respectively.

  8. Degradation of picosecond temporal contrast of Ti:sapphire lasers with coherent pedestals.

    Science.gov (United States)

    Khodakovskiy, Nikita; Kalashnikov, Mikhail; Gontier, Emilien; Falcoz, Franck; Paul, Pierre-Mary

    2016-10-01

    Recompressed pulses from Ti:sapphire chirped-pulse lasers are accompanied by a slowly decaying post-pulse pedestal that is coherent with the main pulse. The pedestal typically consists of numerous pulses with temporal separation in the picosecond range. The source of this artifact lies in the Ti:sapphire active medium itself, both in the Kerr-lens mode-locked oscillator and in subsequent amplifiers. In the presence of substantial self-phase modulation, after recompression the post-pedestal generates a mirror-symmetric pre-pulse pedestal. This pedestal severely degrades the leading edge of the output pulse. This degradation is far more limiting than the original post-pedestal and severely lowers the achievable temporal contrast.

  9. Achieving λ/10 resolution CW STED nanoscopy with a Ti:Sapphire oscillator.

    Directory of Open Access Journals (Sweden)

    Yujia Liu

    Full Text Available In this report, a Ti:Sapphire oscillator was utilized to realize synchronization-free stimulated emission depletion (STED microscopy. With pump power of 4.6 W and sample irradiance of 310 mW, we achieved super-resolution as high as 71 nm. With synchronization-free STED, we imaged 200 nm nanospheres as well as all three cytoskeletal elements (microtubules, intermediate filaments, and actin filaments, clearly demonstrating the resolving power of synchronization-free STED over conventional diffraction limited imaging. It also allowed us to discover that, Dylight 650, exhibits improved performance over ATTO647N, a fluorophore frequently used in STED. Furthermore, we applied synchronization-free STED to image fluorescently-labeled intracellular viral RNA granules, which otherwise cannot be differentiated by confocal microscopy. Thanks to the widely available Ti:Sapphire oscillators in multiphoton imaging system, this work suggests easier access to setup super-resolution microscope via the synchronization-free STED.

  10. Characterization of superconducting magnesium-diboride films on glassy carbon and sapphire substrates

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, E.; Zavala, E. P. [Instituto de Fisica, UNAM, Apartado Postal 20-364, 01000 Mexico D. F. (Mexico); Rocha, M. F. [Escuela Superior de Ingenieria Mecanica y Electrica, IPN, Mexico D. F. (Mexico); Jergel, M.; Falcony, C. [Departamento de Fisica, CINVESTAV-IPN, Apartado postal 14-740, 07000 Mexico D. F. (Mexico)

    2008-02-15

    IBA methods were applied to measure elemental depth profiles of precursors and superconducting MgB{sub 2} thin films deposited on glassy carbon (Good Fellows) and sapphire (Al{sub 2}O{sub 3}) substrates. For each type of substrates we obtained a pair of samples i.e. one amorphous precursor and one superconducting film which were then characterized. A 3{sup H}e{sup +} beam was used to bombard both, precursors and superconducting films in order to obtain the samples elemental composition profiles. The zero resistance T{sub co} and the middle of transition T{sub cm} values were 26.0 K and 29.7 K for the MgB{sub 2} film deposited on glassy carbon substrate. In the case of sapphire substrate the T{sub co} and T{sub cm} values were 25.0 K and 27.9 K, respectively. (Author)

  11. Nearly octave-spanning frequency comb generation in AlN-on-sapphire microresonators

    CERN Document Server

    Liu, Xianwen; Xiong, Bing; Wang, Lai; Wang, Jian; Han, Yanjun; Hao, Zhibiao; Li, Hongtao; Luo, Yi; Yan, Jianchang; Wei, Tongbo; Zhang, Yun; Wang, Junxi

    2016-01-01

    We report a nearly octave-spanning optical frequency comb generation with a coverage of $\\sim$1000 nm in continuous-wave pumped aluminum nitride (AlN)-on-sapphire microring resonators. Thanks to optimized device design and fabrication process, high-quality-factor AlN microrings with high cavity finesse and low insertion loss are demonstrated. By tailoring the cavity dimension, a broadband anomalous dispersion is secured to facilitate the frequency comb generation. Blue-shifted dispersive wave emission as well as stimulated Raman scattering is observed, which helps extend the comb spectrum coverage. Our work suggests that AlN-on-sapphire can be an appealing platform for integrated nonlinear optics.

  12. Structural, transport and microwave properties of 123/sapphire films: Thickness effect

    Energy Technology Data Exchange (ETDEWEB)

    Predtechensky, MR.; Smal, A.N.; Varlamov, Y.D. [Institute of Thermophysics, Novosibirsk (Russian Federation)] [and others

    1994-12-31

    The effect of thickness and growth conditions on the structure and microwave properties has been investigated for the 123/sapphire films. It has been shown that in the conditions of epitaxial growth and Al atoms do not diffuse from substrate into the film and the films with thickness up to 100nm exhibit the excellent DC properties. The increase of thickness of GdBaCuO films causes the formation of extended line-mesh defects and the increase of the surface resistance (R{sub S}). The low value of surface resistance R{sub S}(75GHz,77K)=20 mOhm has been obtained for the two layer YBaCuO/CdBaCuO/sapphire films.

  13. Use of Be(p,{alpha}) and Be(p,d) Reactions to Determine Be Content in Sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Franklyn, C. B. [Radiation Science Department, Necsa, PO Box 582, Pretoria 0001 (South Africa)

    2011-12-13

    Since natural coloured sapphire ({alpha}-Al{sub 2}O{sub 3}) commands a high gem stone market price there is a need for a reliable method of identifying artificially coloured sapphire that has an inherently lower value. Diffusing beryllium into sapphire at high temperatures results in a coloured stone virtually indistinguishable from a natural one. Beryllium can occur naturally in sapphire but at levels of <1 ppma. Beryllium diffused sapphire typically contains >10 ppma, which is difficult to determine in a non destructive way. It is possible to utilize nuclear reaction analysis techniques to determine the beryllium content in a macroscopically non destructive way. Kinematically ideal reactions are Be(p,{alpha}) and Be(p,d) which, for Ep = 0.5 to 0.9 MeV, exhibit distinct reaction product signatures well separated from other proton induced reactions in aluminium or oxygen. Due to the lack of comprehensive cross section data for the Be(p,{alpha}) and Be(p,d) reactions in the energy range of interest, a series of measurements were made at the Van de Graaff accelerator facility at Necsa to create a new data base. A further outcome of these measurements was a deviation in reported values for the non-Rutherfordian proton back-scatter cross section. These new data bases, which extend to Ep = 2.6MeV, can now facilitate a procedure for determining beryllium content in sapphire.

  14. Evaluation of heat extraction through sapphire fibers for the GW observatory KAGRA

    OpenAIRE

    Khalaidovski, Alexander; Hofmann, Gerd; CHEN, DAN; Komma, Julius; Schwarz, Christian; Tokoku, Chihiro; Kimura, Nobuhiro; Suzuki, Toshikazu; Scheie, Allen O.; Majorana, Ettore; Nawrodt, Ronny; Yamamoto, Kazuhiro

    2014-01-01

    Currently, the Japanese gravitational wave laser interferometer KAGRA is under construction in the Kamioka mine. As one main feature, it will employ sapphire mirrors operated at a temperature of 20K to reduce the impact from thermal noise. To reduce seismic noise, the mirrors will also be suspended from multi-stage pendulums. Thus the heat load deposited in the mirrors by absorption of the circulating laser light as well as heat load from thermal radiation will need to be extracted through th...

  15. High energy terahertz pulses from organic crystals: DAST and DSTMS pumped at Ti:sapphire wavelength

    CERN Document Server

    Monoszlai, B; Jazbinsek, M; Hauri, C P

    2013-01-01

    High energy terahertz pulses are produced by optical rectification (OR) in organic crystals DAST and DSTMS by a Ti:sapphire amplifier system centered at 0.8 microns. The simple scheme provides broadband spectra between 1 and 5 THz, when pumped by collimated 60 fs near-infrared pump pulse and it is scalable in energy. Fluence-dependent conversion efficiency and damage threshold are reported as well as optimized OR at visible wavelength.

  16. Silicon-on-Sapphire Waveguides: Mode-converting Couplers and Four-wave Mixing

    Science.gov (United States)

    2014-09-01

    width of the waveguides was between 1600 and 1900 nm . Figure 1 shows gain bands for a waveguide with 500- nm height and 1700 - nm width, demonstrating...1. Calculated conversion efficiency of four-wave mixing in 1700 - nm wide silicon-on-sapphire waveguide. Color bar indicates conversion efficiency in...dominance. Previous investigations show that this spectral range is of interest for applications that include free-space communications, laser radar

  17. ZnO Nanostructures Grown on AlN/Sapphire Substrates by MOCVD

    Institute of Scientific and Technical Information of China (English)

    WEI Hong-Yuan; HU Wei-Guo; ZHANG Pan-Feng; LIU Xiang-Lin; ZHU Qin-Sheng; WANG Zhan-Guo

    2007-01-01

    ZnO nanorods and nanotubes are successful synthesized on AlN/sapphire substrates by metal-organic chemical vapour deposition (MOCVD). The different morphology and structure properties of ZnO nanorods and nanotubes are found to be affected by the A1N under-layer. The photoluminescence spectra show the optical properties of the ZnO nanorods and nanotubes, in which a blueshift of UV emission is observed and is attributed to the surface effect.

  18. Femtosecond Ti:sapphire cryogenic amplifier with high gain and MHz repetition rate.

    Science.gov (United States)

    Dantan, Aurélien; Laurat, Julien; Ourjoumtsev, Alexei; Tualle-Brouri, Rosa; Grangier, Philippe

    2007-07-09

    We demonstrate high gain amplification of 160-femtosecond pulses in a compact double-pass cryogenic Ti:sapphire amplifier. The setup involves a negative GVD mirrors recompression stage, and operates with a repetition rate between 0.2 and 4 MHz with a continuous pump laser. Amplification factors as high as 17 and 320 nJ Fourier-limited pulses are obtained at a 800 kHz repetition rate.

  19. Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika

    2011-01-01

    electro-optical efficiency of the diode laser. Autocorrelation measurements show that pulse widths of less than 20 fs can be expected with an average power of 52 mW when using our laser. These results indicate the high potential of direct diode laser pumped Ti: sapphire lasers to be used in applications...... like retinal optical coherence tomography (OCT) or pumping of photonic crystal fibers for CARS (coherent anti-stokes Raman spectroscopy) microscopy....

  20. A microwave exciter for Cs frequency standards based on a sapphire-loaded cavity oscillator.

    Science.gov (United States)

    Koga, Y; McNeilage, C; Searls, J H; Ohshima, S

    2001-01-01

    A low noise and highly stable microwave exciter system has been built for Cs atomic frequency standards using a tunable sapphire-loaded cavity oscillator (SLCO), which works at room temperature. This paper discusses the successful implementation of a control system for locking the SLCO to a long-term reference signal and reports an upper limit of the achieved frequency tracking error 6 x 10(-15) at tau = 1 s.