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Sample records for optically activated high

  1. Magneto-Optical Activity in High Index Dielectric Nanoantennas

    CERN Document Server

    de Sousa, N; Sáenz, J J; García-Martín, A

    2016-01-01

    The magneto-optical activity, namely the polarization conversion capabilities of high-index, non-absorbing, core-shell dielectric nanospheres is theoretically analyzed. We show that, in analogy with their plasmonic counterparts, the polarization conversion in resonant dielectric particles is linked to the amount of electromagnetic field probing the magneto-optical material in the system. However, in strong contrast with plasmon nanoparticles, due to the peculiar distribution of the internal fields in resonant dielectric spheres, the magneto-optical response is fully governed by the magnetic (dipolar and quadrupolar) resonances with little effect of the electric ones.

  2. Active optics for high-dynamic variable curvature mirrors

    CERN Document Server

    Hugot, Emmanuel; Lemaitre, Gerard R; Madec, Fabrice; Vives, Sebastien; Chardin, Elodie; Mignant, David Le; Cuby, Jean Gabriel

    2014-01-01

    Variable curvature mirrors of large amplitude are designed by using finite element analysis. The specific case studied reaches at least a 800 {\\mu}m sag with an optical quality better than {\\lambda}/5 over a 120 mm clear aperture. We highlight the geometrical nonlinearity and the plasticity effect.

  3. High-temperature optically activated GaAs power switching for aircraft digital electronic control

    Science.gov (United States)

    Berak, J. M.; Grantham, D. H.; Swindal, J. L.; Black, J. F.; Allen, L. B.

    1983-01-01

    Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas.

  4. High-power fiber optic cable with integrated active sensors for live process monitoring

    Science.gov (United States)

    Blomster, Ola; Blomqvist, Mats; Bergstrand, Hans; Pålsson, Magnus

    2012-03-01

    In industrial applications using high-brilliance lasers at power levels up to and exceeding 20 kW and similarly direct diode lasers of 10 kW, there is an increasing demand to continuously monitor component status even in passive components such as fiber-optic cables. With fiber-optic cables designed according to the European Automotive Industry fiber standard interface there is room for integrating active sensors inside the connectors. In this paper we present the integrated active sensors in the new Optoskand QD fiber-optic cable designed to handle extreme levels of power losses, and how these sensors can be employed in industrial manufacturing. The sensors include photo diodes for detection of scattered light inside the fiber connector, absolute temperature of the fiber connector, difference in temperature of incoming and outgoing cooling water, and humidity measurement inside the fiber connector. All these sensors are connected to the fiber interlock system, where interlock break enable functions can be activated when measured signals are higher than threshold levels. It is a very fast interlock break system as the control of the signals is integrated in the electronics inside the fiber connector. Also, since all signals can be logged it is possible to evaluate what happened inside the connector before the interlock break instance. The communication to the fiber-optic connectors is via a CAN interface. Thus it is straightforward to develop the existing laser host control to also control the CAN-messages from the QD sensors.

  5. Active learning of geometrical optics in high school: the ALOP approach

    Science.gov (United States)

    Alborch, Alejandra; Pandiella, Susana; Benegas, Julio

    2017-09-01

    A group comparison experiment of two high school classes with pre and post instruction testing has been carried out to study the suitability and advantages of using the active learning of optics and photonics (ALOP) curricula in high schools of developing countries. Two parallel, mixed gender, 12th grade classes of a high school run by the local university were chosen. One course was randomly selected to follow the experimental instruction, based on teacher and student activities contained in the ALOP Manual. The other course followed the traditional, teacher-centered, instruction previously practiced. Conceptual knowledge of the characteristics of image formation by plane mirrors and single convergent and divergent lenses was measured by applying, in both courses, the multiple-choice test, light and optics conceptual evaluation (LOCE). Measurement before instruction showed that initial knowledge was almost null, and therefore equivalent, in both courses. After instruction testing showed that the conceptual knowledge of students following the ALOP curricula more than doubled that achieved by students in the control course, a situation maintained throughout the six conceptual dimensions tested by the 34 questions of the LOCE test used in this experiment. Using a 60% performance level on the LOCE test as the threshold of satisfactory performance, most (about 90%) of the experimental group achieved this level—independent of initial knowledge, while no student following traditional instruction reached this level of understanding. Some considerations and recommendations for prospective users are also included.

  6. Active optical zoom system

    Science.gov (United States)

    Wick, David V.

    2005-12-20

    An active optical zoom system changes the magnification (or effective focal length) of an optical imaging system by utilizing two or more active optics in a conventional optical system. The system can create relatively large changes in system magnification with very small changes in the focal lengths of individual active elements by leveraging the optical power of the conventional optical elements (e.g., passive lenses and mirrors) surrounding the active optics. The active optics serve primarily as variable focal-length lenses or mirrors, although adding other aberrations enables increased utility. The active optics can either be LC SLMs, used in a transmissive optical zoom system, or DMs, used in a reflective optical zoom system. By appropriately designing the optical system, the variable focal-length lenses or mirrors can provide the flexibility necessary to change the overall system focal length (i.e., effective focal length), and therefore magnification, that is normally accomplished with mechanical motion in conventional zoom lenses. The active optics can provide additional flexibility by allowing magnification to occur anywhere within the FOV of the system, not just on-axis as in a conventional system.

  7. Long Term Optical and Infrared Reverberation Mapping of High and Low Luminosity Active Galactic Nuclei

    Science.gov (United States)

    Gorjian, Varoujan; Barth, Aaron; Brandt, Niel; Dawson, Kyle; Green, Paul; Ho, Luis; Horne, Keith; Jiang, Linhua; Joner, Mike; Kenney, John; McGreer, Ian; Nordgren, Tyler; Schneider, Donald; Shen, Yue; Tao, Charling

    2016-08-01

    Previous Spitzer reverberation monitoring projects looking for UV/optical light absorbed and re-emitted in the IR by dust have been limited to very low luminosity active galactic nuclei (AGN) that could potentially show reverberation within a single cycle (~1 year). Cycle 11-12's two year baseline allowed for the reverberation mapping of 17 high luminosity quasars from the Sloan Digital Sky Survey Reverberation Mapping project. By combining ground based monitoring from Pan-STARRS, CFHT, and Steward Observatory telescopes with Spitzer data we have for the first time detected dust reverberation in quasars. We propose to continue this project to capitalize on the continuing optical motnoring from the ground and to increase the confidence in the detected lags. Additionally, the Call for Proposals asks for up to 1000 hours of observations in the Spitzer CVZ to accommodate battery charging needs. We propose to add to our quasar sample five lower luminosity Seyfert galaxies from the Pan-STARRS ground based optical survey that are in the Spitzer CVZ, which will increase the luminosity range of AGN we are studying and, combined with additional ground based observatories, provide for a continuous monitoring campaign lasting 2 years and thus provide the most detailed study of dust around AGN to date.

  8. Optical Design and Active Optics Methods in Astronomy

    CERN Document Server

    Lemaitre, Gerard R

    2013-01-01

    Optical designs for astronomy involve implementation of active optics and adaptive optics from X-ray to the infrared. Developments and results of active optics methods for telescopes, spectrographs and coronagraph planet finders are presented. The high accuracy and remarkable smoothness of surfaces generated by active optics methods also allow elaborating new optical design types with high aspheric and/or non-axisymmetric surfaces. Depending on the goal and performance requested for a deformable optical surface analytical investigations are carried out with one of the various facets of elasticity theory: small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, weakly conical shell theory. The resulting thickness distribution and associated bending force boundaries can be refined further with finite element analysis. Keywords: active optics, optical design, elasticity theory, astronomical optics, diffractive optics, X-ray optics

  9. High-speed linear optics quantum computing using active feed-forward.

    Science.gov (United States)

    Prevedel, Robert; Walther, Philip; Tiefenbacher, Felix; Böhi, Pascal; Kaltenbaek, Rainer; Jennewein, Thomas; Zeilinger, Anton

    2007-01-04

    As information carriers in quantum computing, photonic qubits have the advantage of undergoing negligible decoherence. However, the absence of any significant photon-photon interaction is problematic for the realization of non-trivial two-qubit gates. One solution is to introduce an effective nonlinearity by measurements resulting in probabilistic gate operations. In one-way quantum computation, the random quantum measurement error can be overcome by applying a feed-forward technique, such that the future measurement basis depends on earlier measurement results. This technique is crucial for achieving deterministic quantum computation once a cluster state (the highly entangled multiparticle state on which one-way quantum computation is based) is prepared. Here we realize a concatenated scheme of measurement and active feed-forward in a one-way quantum computing experiment. We demonstrate that, for a perfect cluster state and no photon loss, our quantum computation scheme would operate with good fidelity and that our feed-forward components function with very high speed and low error for detected photons. With present technology, the individual computational step (in our case the individual feed-forward cycle) can be operated in less than 150 ns using electro-optical modulators. This is an important result for the future development of one-way quantum computers, whose large-scale implementation will depend on advances in the production and detection of the required highly entangled cluster states.

  10. Active optical clock

    Institute of Scientific and Technical Information of China (English)

    CHEN JingBiao

    2009-01-01

    This article presents the principles and techniques of active optical clock, a special laser combining the laser physics of one-atom laser, bad-cavity gas laser, super-cavity stabilized laser and optical atomic clock together. As a simple example, an active optical clock based on thermal strontium atomic beam shows a quantum-limited linewidth of 0.51 Hz, which is insensitive to laser cavity-length noise, and may surpass the recorded narrowest 6.7 Hz of Hg ion optical clock and 1.5 Hz of very recent optical lattice clock. The estimated 0.1 Hz one-second instability and 0.27 Hz uncertainty are limited only by the rela-tivistic Doppler effect, and can be improved by cold atoms.

  11. Active Optics in LAMOST

    Institute of Scientific and Technical Information of China (English)

    Ding-Qiang Su; Xiang-Qun Cui

    2004-01-01

    Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)is one of the major national projects under construction in China. Active optics is one of the most important technologies for new large telescopes. It is used for correcting telescope errors generated by gravitational and thermal changes. Here,however, we use this technology to realize the configuration of LAMOST, -a task that cannot be done in the traditional way. A comprehensive and intensive research on the active optics used in LAMOST is also reported, including an open-loop control method and an auxiliary closed-loop control method. Another important development is in our pre-calibration method of open-loop control, which is with some new features: simultaneous calculation of the forces and displacements of force actuators and displacement actuators; the profile of mirror can be arbitrary;the mirror surface shape is not expressed by a fitting polynomial, but is derived from the mirror surface shape formula which is highly accurate; a proof is given that the solution of the pre-calibration method is the same as the least squares solution.

  12. Toroidal optical activity

    CERN Document Server

    Raybould, T A; Papasimakis, N; Kuprov, I; Youngs, I; Chen, W T; Tsai, D P; Zheludev, N I

    2015-01-01

    Optical activity is ubiquitous across natural and artificial media and is conventionally understood in terms of scattering from electric and magnetic moments. Here we demonstrate experimentally and confirm numerically a type of optical activity that cannot be attributed to electric and magnetic multipoles. We show that our observations can only be accounted for by the inclusion of the toroidal dipole moment, the first term of the recently established peculiar family of toroidal multipoles.

  13. Highly Sensitive Optical Receivers

    CERN Document Server

    Schneider, Kerstin

    2006-01-01

    Highly Sensitive Optical Receivers primarily treats the circuit design of optical receivers with external photodiodes. Continuous-mode and burst-mode receivers are compared. The monograph first summarizes the basics of III/V photodetectors, transistor and noise models, bit-error rate, sensitivity and analog circuit design, thus enabling readers to understand the circuits described in the main part of the book. In order to cover the topic comprehensively, detailed descriptions of receivers for optical data communication in general and, in particular, optical burst-mode receivers in deep-sub-µm CMOS are presented. Numerous detailed and elaborate illustrations facilitate better understanding.

  14. Conformal metasurface-coated dielectric waveguides for highly confined broadband optical activity with simultaneous low-visibility and reduced crosstalk.

    Science.gov (United States)

    Jiang, Zhi Hao; Kang, Lei; Werner, Douglas H

    2017-08-25

    The ability to achieve simultaneous control over the various electromagnetic properties of dielectric waveguides, including mode confinement, polarization, scattering signature, and crosstalk, which are critical to system miniaturization, diversity in functionality, and non-invasive integration, has been a highly sought after yet elusive goal. Currently existing methods, which rely on three-dimensional artificial cores or claddings and/or structural chirality, provide efficient paths for obtaining either highly confined modes, optical activity, or a low-scattering signature, but at the expense of increased propagation loss, form factor and weight. Here, by tailoring the unique anisotropy and exploiting the inter-cell coupling of metasurface coatings, we report a unified approach for simultaneously controlling the diverse optical properties of dielectric waveguides. The experimentally demonstrated highly confined sub-wavelength dielectric waveguide with a low-visibility and broadband optical activity represents a transformative wave manipulation capability with far reaching implications, offering new pathways for future miniaturization of dielectric waveguide-based systems with simultaneous polarization and scattering control.Controlling all the optical properties of dielectric waveguides is a challenging task and often requires complicated core- and cladding designs. Here, Jiang et al. demonstrate that a thin metasurface coating can control several optical properties simultaneously over a broad frequency range.

  15. High speed optical networks

    Science.gov (United States)

    Frankel, Michael Y.; Livas, Jeff

    2005-02-01

    This overview will discuss core network technology and cost trade-offs inherent in choosing between "analog" architectures with high optical transparency, and ones heavily dependent on frequent "digital" signal regeneration. The exact balance will be related to the specific technology choices in each area outlined above, as well as the network needs such as node geographic spread, physical connectivity patterns, and demand loading. Over the course of a decade, optical networks have evolved from simple single-channel SONET regenerator-based links to multi-span multi-channel optically amplified ultra-long haul systems, fueled by high demand for bandwidth at reduced cost. In general, the cost of a well-designed high capacity system is dominated by the number of optical to electrical (OE) and electrical to optical (EO) conversions required. As the reach and channel capacity of the transport systems continued to increase, it became necessary to improve the granularity of the demand connections by introducing (optical add/drop multiplexers) OADMs. Thus, if a node requires only small demand connectivity, most of the optical channels are expressed through without regeneration (OEO). The network costs are correspondingly reduced, partially balanced by the increased cost of the OADM nodes. Lately, the industry has been aggressively pursuing a natural extension of this philosophy towards all-optical "analog" core networks, with each demand touching electrical digital circuitry only at the in/egress nodes. This is expected to produce a substantial elimination of OEO costs, increase in network capacity, and a notionally simpler operation and service turn-up. At the same time, such optical "analog" network requires a large amount of complicated hardware and software for monitoring and manipulating high bit rate optical signals. New and more complex modulation formats that provide resiliency to both optical noise and nonlinear propagation effects are important for extended

  16. Optically active quantum dots

    Science.gov (United States)

    Gerard, Valerie; Govan, Joseph; Loudon, Alexander; Baranov, Alexander V.; Fedorov, Anatoly V.; Gun'ko, Yurii K.

    2015-10-01

    The main goal of our research is to develop new types of technologically important optically active quantum dot (QD) based materials, study their properties and explore their biological applications. For the first time chiral II-VI QDs have been prepared by us using microwave induced heating with the racemic (Rac), D- and L-enantiomeric forms of penicillamine as stabilisers. Circular dichroism (CD) studies of these QDs have shown that D- and L-penicillamine stabilised particles produced mirror image CD spectra, while the particles prepared with a Rac mixture showed only a weak signal. It was also demonstrated that these QDs show very broad emission bands between 400 and 700 nm due to defects or trap states on the surfaces of the nanocrystals. These QDs have demonstrated highly specific chiral recognition of various biological species including aminoacids. The utilisation of chiral stabilisers also allowed the preparation of new water soluble white emitting CdS nano-tetrapods, which demonstrated circular dichroism in the band-edge region of the spectrum. Biological testing of chiral CdS nanotetrapods displayed a chiral bias for an uptake of the D- penicillamine stabilised nano-tetrapods by cancer cells. It is expected that this research will open new horizons in the chemistry of chiral nanomaterials and their application in nanobiotechnology, medicine and optical chemo- and bio-sensing.

  17. Highly selective anti-Prelog synthesis of optically active aryl alcohols by recombinant Escherichia coli expressing stereospecific alcohol dehydrogenase.

    Science.gov (United States)

    Li, Ming; Nie, Yao; Mu, Xiao Qing; Zhang, Rongzhen; Xu, Yan

    2016-07-03

    Biocatalytic asymmetric synthesis has been widely used for preparation of optically active chiral alcohols as the important intermediates and precursors of active pharmaceutical ingredients. However, the available whole-cell system involving anti-Prelog specific alcohol dehydrogenase is yet limited. A recombinant Escherichia coli system expressing anti-Prelog stereospecific alcohol dehydrogenase from Candida parapsilosis was established as a whole-cell system for catalyzing asymmetric reduction of aryl ketones to anti-Prelog configured alcohols. Using 2-hydroxyacetophenone as the substrate, reaction factors including pH, cell status, and substrate concentration had obvious impacts on the outcome of whole-cell biocatalysis, and xylose was found to be an available auxiliary substrate for intracellular cofactor regeneration, by which (S)-1-phenyl-1,2-ethanediol was achieved with an optical purity of 97%e.e. and yield of 89% under the substrate concentration of 5 g/L. Additionally, the feasibility of the recombinant cells toward different aryl ketones was investigated, and most of the corresponding chiral alcohol products were obtained with an optical purity over 95%e.e. Therefore, the whole-cell system involving recombinant stereospecific alcohol dehydrogenase was constructed as an efficient biocatalyst for highly enantioselective anti-Prelog synthesis of optically active aryl alcohols and would be promising in the pharmaceutical industry.

  18. An investigation of the influence of reconceptualization of demonstrative experimental activities of optics in high school

    Directory of Open Access Journals (Sweden)

    Jair Lúcio Prados Ribeiro

    2013-08-01

    Full Text Available In this work, we analyze the influence that the use of demonstrative experiments can bring to the learning of optics. It is assumed that the development of experimental activities, when reconceptualized according to Hodson proposal, tends to contribute to the generation of cognitive conflicts when compared to traditional didactic experience. Justifications are given for an analysis of changes under a Piagetian bias, reconciled with Hodson proposal. The methodology used to structure the topics presentations was quasi-experimental, contrasting an experimental group with a control group. The measuring of the effectiveness of the suggested working method was made from a quantitative analysis, which identified some of the topics discussed had better results in learning, being more tied to the experiments carried out.

  19. Optical design and active optics methods in astronomy

    Science.gov (United States)

    Lemaitre, Gerard R.

    2013-03-01

    Optical designs for astronomy involve implementation of active optics and adaptive optics from X-ray to the infrared. Developments and results of active optics methods for telescopes, spectrographs and coronagraph planet finders are presented. The high accuracy and remarkable smoothness of surfaces generated by active optics methods also allow elaborating new optical design types with high aspheric and/or non-axisymmetric surfaces. Depending on the goal and performance requested for a deformable optical surface analytical investigations are carried out with one of the various facets of elasticity theory: small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, weakly conical shell theory. The resulting thickness distribution and associated bending force boundaries can be refined further with finite element analysis.

  20. A tunnel regenerated coupled multi-active-region large optical cavity laser with a high quality beam

    Institute of Scientific and Technical Information of China (English)

    Cui Bi-Feng; Guo Wei-Ling; Du Xiao-Dong; Li Jian-Jun; Zou De-Shu; Shen Guang-Di

    2012-01-01

    A novel coupled multi-active-region large optical cavity structure cascaded by a tunnel junction is proposed to solve the problems of facet catastrophic optical damage (COD) and the large vertical divergence caused by the thin emitting area in conventional laser diodes.For a laser with three active regions,a slope efficiency as high as 1.49 W/A,a vertical divergence angle of 17.4°,and a threshold current density of 271 A/cm2 are achieved.By optimizing the structural parameters,the beam quality is greatly improved,and the level of the COD power increases by more than two times compared with that of the conventional laser.

  1. Actively coupled optical waveguides

    OpenAIRE

    Alexeeva, N. V.; Barashenkov, I. V.; Rayanov, K.; Flach, S.

    2013-01-01

    We consider light propagation through a pair of nonlinear optical waveguides with absorption, placed in a medium with power gain. The active medium boosts the in-phase component of the overlapping evanescent fields of the guides, while the nonlinearity of the guides couples it to the damped out-of-phase component creating a feedback loop. As a result, the structure exhibits stable stationary and oscillatory regimes in a wide range of gain-loss ratios. We show that the pair of actively-coupled...

  2. Actively coupled optical waveguides

    Science.gov (United States)

    Alexeeva, N. V.; Barashenkov, I. V.; Rayanov, K.; Flach, S.

    2014-01-01

    We consider light propagation through a pair of nonlinear optical waveguides with absorption, placed in a medium with power gain. The active medium boosts the in-phase component of the overlapping evanescent fields of the guides, while the nonlinearity of the guides couples it to the damped out-of-phase component creating a feedback loop. As a result, the structure exhibits stable stationary and oscillatory regimes in a wide range of gain-loss ratios. We show that the pair of actively coupled (AC) waveguides can act as a stationary or integrate-and-fire comparator sensitive to tiny differences in their input powers.

  3. High-resolution wind speed measurements using actively heated fiber optics

    Science.gov (United States)

    Sayde, Chadi; Thomas, Christoph K.; Wagner, James; Selker, John

    2015-11-01

    We present a novel technique to simultaneously measure wind speed (U) at thousands of locations continuously in time based on measurement of velocity-dependent heat transfer from a heated surface. Measuring temperature differences between paired passive and actively heated fiber-optic (AHFO) cables with a distributed temperature sensing system allowed estimation of U at over 2000 sections along the 230 m transect (resolution of 0.375 m and 5.5 s). The underlying concept is similar to that of a hot wire anemometer extended in space. The correlation coefficient between U measured by two colocated sonic anemometers and the AHFO were 0.91 during the day and 0.87 at night. The combination of classical passive and novel AHFO provides unprecedented dynamic observations of both air temperature and wind speed spanning 4 orders of magnitude in spatial scale (0.1-1000 m) while resolving individual turbulent motions, opening new opportunities for testing basic theories for near-surface geophysical flows.

  4. Active X-ray Optics for Generation-X, the Next High Resolution X-ray Observatory

    CERN Document Server

    Elvis, M; Fabbiano, G; Schwartz, D A; Reid, P; Podgorski, W; Eisenhower, M; Juda, M; Phillips, J; Cohen, L; Wolk, S; Elvis, Martin

    2006-01-01

    X-rays provide one of the few bands through which we can study the epoch of reionization, when the first galaxies, black holes and stars were born. To reach the sensitivity required to image these first discrete objects in the universe needs a major advance in X-ray optics. Generation-X (Gen-X) is currently the only X-ray astronomy mission concept that addresses this goal. Gen-X aims to improve substantially on the Chandra angular resolution and to do so with substantially larger effective area. These two goals can only be met if a mirror technology can be developed that yields high angular resolution at much lower mass/unit area than the Chandra optics, matching that of Constellation-X (Con-X). We describe an approach to this goal based on active X-ray optics that correct the mid-frequency departures from an ideal Wolter optic on-orbit. We concentrate on the problems of sensing figure errors, calculating the corrections required, and applying those corrections. The time needed to make this in-flight calibrat...

  5. Integration of active optical components

    Science.gov (United States)

    Wipiejewski, Torsten; Akulova, Yuliya A.; Fish, Gregory A.; Schow, Clint L.; Koh, Ping; Karim, Adil; Nakagawa, Shigeru; Dahl, Anders; Kozodoy, Peter; Matson, Alex; Short, Bradley W.; Turner, Chuck M.; Penniman, Steven; Larson, Michael C.; Coldren, Christopher W.; Coldren, Larry A.

    2003-06-01

    Integration of active optical components typically serves five goals: enhanced performance, smaller space, lower power dissipation, higher reliability, and lower cost. We are manufacturing widely tunable laser diodes with an integrated high speed electro absorption modulator for metro and all-optical switching applications. The monolithic integration combines the functions of high power laser light generation, wavelength tuning over the entire C-band, and high speed signal modulation in a single chip. The laser section of the chip contains two sampled grating DBRs with a gain and a phase section between them. The emission wavelength is tuned by current injection into the waveguide layers of the DBR and phase sections. The laser light passes through an integrated optical amplifier before reaching the modulator section on the chip. The amplifier boosts the cw output power of the laser and provides a convenient way of power leveling. The modulator is based on the Franz-Keldysh effect for a wide band of operation. The common waveguide through all sections minimizes optical coupling losses. The packaging of the monolithically integrated chip is much simpler compared to a discrete or hybrid solution using a laser chip, an SOA, and an external modulator. Since only one optical fiber coupling is required, the overall packaging cost of the transmitter module is largely reduced. Error free transmission at 2.5Gbit/s over 200km of standard single mode fiber is obtained with less than 1dB of dispersion penalty.

  6. Nondispersive optical activity of meshed helical metamaterials.

    Science.gov (United States)

    Park, Hyun Sung; Kim, Teun-Teun; Kim, Hyeon-Don; Kim, Kyungjin; Min, Bumki

    2014-11-17

    Extreme optical properties can be realized by the strong resonant response of metamaterials consisting of subwavelength-scale metallic resonators. However, highly dispersive optical properties resulting from strong resonances have impeded the broadband operation required for frequency-independent optical components or devices. Here we demonstrate that strong, flat broadband optical activity with high transparency can be obtained with meshed helical metamaterials in which metallic helical structures are networked and arranged to have fourfold rotational symmetry around the propagation axis. This nondispersive optical activity originates from the Drude-like response as well as the fourfold rotational symmetry of the meshed helical metamaterials. The theoretical concept is validated in a microwave experiment in which flat broadband optical activity with a designed magnitude of 45° per layer of metamaterial is measured. The broadband capabilities of chiral metamaterials may provide opportunities in the design of various broadband optical systems and applications.

  7. Parallel optical control of spatiotemporal neuronal spike activity using high-frequency digital light processingtechnology

    Directory of Open Access Journals (Sweden)

    Jason eJerome

    2011-08-01

    Full Text Available Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses Digital-Light-Processing (DLP technology to generate 2-dimensional (2D stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 µm and temporal (>13kHz resolution. Light is projected through the quartz-glass bottom of the perfusion chamber providing access to a large area (2.76 x 2.07 mm2 of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales.

  8. Parallel optical control of spatiotemporal neuronal spike activity using high-speed digital light processing.

    Science.gov (United States)

    Jerome, Jason; Foehring, Robert C; Armstrong, William E; Spain, William J; Heck, Detlef H

    2011-01-01

    Neurons in the mammalian neocortex receive inputs from and communicate back to thousands of other neurons, creating complex spatiotemporal activity patterns. The experimental investigation of these parallel dynamic interactions has been limited due to the technical challenges of monitoring or manipulating neuronal activity at that level of complexity. Here we describe a new massively parallel photostimulation system that can be used to control action potential firing in in vitro brain slices with high spatial and temporal resolution while performing extracellular or intracellular electrophysiological measurements. The system uses digital light processing technology to generate 2-dimensional (2D) stimulus patterns with >780,000 independently controlled photostimulation sites that operate at high spatial (5.4 μm) and temporal (>13 kHz) resolution. Light is projected through the quartz-glass bottom of the perfusion chamber providing access to a large area (2.76 mm × 2.07 mm) of the slice preparation. This system has the unique capability to induce temporally precise action potential firing in large groups of neurons distributed over a wide area covering several cortical columns. Parallel photostimulation opens up new opportunities for the in vitro experimental investigation of spatiotemporal neuronal interactions at a broad range of anatomical scales.

  9. High Prf Metal Vapor Laser Active Media For Visual And Optical Monitoring

    Science.gov (United States)

    Torgaev, S. N.; Trigub, M. V.; Evtushenko, G. S.; Evtushenko, T. G.

    2016-01-01

    In this paper the feasibility of using metal vapor lasers for visual and optical monitoring of fast processes is discussed. The theoretical calculations consistent with the experimental study have been performed. The possibility of visualizing objects with pulse repetition frequency of the brightness amplifier up to 60 kHz has been demonstrated. The visualization results of the corona discharge are also given.

  10. The Study of Active Atoms in High-Voltage Pulsed Coronal Discharge by Optical Diagnostics

    Institute of Scientific and Technical Information of China (English)

    Liu Feng; Wang Wenchun; Wang Su; Ren Chunsheng; Wang Younian

    2005-01-01

    In this study, the emission spectra of active atoms O (3p5P → 3s5S20 777.4 nm),Ha (3P → 2S 656.3 nm) and N (3p4P → 3s4S0 742.3 nm, 744.2 nm, 746.8 nm) produced by thepositive high-voltage pulsed corona discharge (HVPCD) of N2 and H2O mixture in a needle-platereactor have successfully been recorded against a severe electromagnetic interference coming fromthe HVPCD at one atmosphere. The effects of the peak voltage, the repetition rate of pulseddischarge and the flow rate of oxygen on the production of those active atoms are investigated. Itis found that when the peak voltage and the repetition rate of the pulsed discharge are increased,the emission intensities of those active atoms rise correspondingly. And the emission intensities ofO (3p5P → 3s5S20 777.4 nm), Ha (3P → 2S 656.3 nm) and N (3p4P → 3s4S0 742.3 nm, 744.2 nm,746.8 nm) increase with the flow rate of oxygen (from 0 to 25 ml/min) and achieve a maximumvalue at a flow rate of 25 ml/min. When the flow rate of oxygen is increased further, the emissionintensities of those atoms visibly decrease correspondingly. The main physicochemical processesof interaction involved between electrons, neutrals and ions are also discussed.

  11. Optical engineering application of modeled photosynthetically active radiation (PAR) for high-speed digital camera dynamic range optimization

    Science.gov (United States)

    Alves, James; Gueymard, Christian A.

    2009-08-01

    As efforts to create accurate yet computationally efficient estimation models for clear-sky photosynthetically active solar radiation (PAR) have succeeded, the range of practical engineering applications where these models can be successfully applied has increased. This paper describes a novel application of the REST2 radiative model (developed by the second author) in optical engineering. The PAR predictions in this application are used to predict the possible range of instantaneous irradiances that could impinge on the image plane of a stationary video camera designed to image license plates on moving vehicles. The overall spectral response of the camera (including lens and optical filters) is similar to the 400-700 nm PAR range, thereby making PAR irradiance (rather than luminance) predictions most suitable for this application. The accuracy of the REST2 irradiance predictions for horizontal surfaces, coupled with another radiative model to obtain irradiances on vertical surfaces, and to standard optical image formation models, enable setting the dynamic range controls of the camera to ensure that the license plate images are legible (unsaturated with adequate contrast) regardless of the time of day, sky condition, or vehicle speed. A brief description of how these radiative models are utilized as part of the camera control algorithm is provided. Several comparisons of the irradiance predictions derived from the radiative model versus actual PAR measurements under varying sky conditions with three Licor sensors (one horizontal and two vertical) have been made and showed good agreement. Various camera-to-plate geometries and compass headings have been considered in these comparisons. Time-lapse sequences of license plate images taken with the camera under various sky conditions over a 30-day period are also analyzed. They demonstrate the success of the approach at creating legible plate images under highly variable lighting, which is the main goal of this

  12. High-quality MOVPE butt-joint integration of InP/AlGaInAs/InGaAsP-based all-active optical components

    DEFF Research Database (Denmark)

    Kulkova, Irina; Kadkhodazadeh, Shima; Kuznetsova, Nadezda

    2014-01-01

    In this paper, we demonstrate the applicability of MOVPE butt-joint regrowth for integration of all-active InP/AlGaAs/InGaAsP optical components and the realization of high-functionality compact photonic devices. Planar high-quality integration of semiconductor optical amplifiers of various epi......-structures with a multi-quantum well electro-absorption modulator has been successfully performed and their optical and crystalline quality was experimentally investigated. The regrown multi-quantum well material exhibits a slight bandgap blue-shift of less than 20 meV, when moving away from the regrowth interface...

  13. Active Faraday optical frequency standard.

    Science.gov (United States)

    Zhuang, Wei; Chen, Jingbiao

    2014-11-01

    We propose the mechanism of an active Faraday optical clock, and experimentally demonstrate an active Faraday optical frequency standard based on narrow bandwidth Faraday atomic filter by the method of velocity-selective optical pumping of cesium vapor. The center frequency of the active Faraday optical frequency standard is determined by the cesium 6 (2)S(1/2) F=4 to 6 (2)P(3/2) F'=4 and 5 crossover transition line. The optical heterodyne beat between two similar independent setups shows that the frequency linewidth reaches 281(23) Hz, which is 1.9×10(4) times smaller than the natural linewidth of the cesium 852-nm transition line. The maximum emitted light power reaches 75 μW. The active Faraday optical frequency standard reported here has advantages of narrow linewidth and reduced cavity pulling, which can readily be extended to other atomic transition lines of alkali and alkaline-earth metal atoms trapped in optical lattices at magic wavelengths, making it useful for new generation of optical atomic clocks.

  14. Optically Active Organic Microrings

    DEFF Research Database (Denmark)

    Balzer, Frank; Beermann, J.; Bozhevolnyi, S.I.

    2003-01-01

    -hexaphenyl molecules are generated on mica surfaces, possessing narrow size distributions with mean diameters of a few micrometers, wall widths of 100 to 200 nm, and wall heights of several hundred nanometers. Polarized linear and nonlinear optics reveals that the rings are made up of radially...

  15. Simultaneous production of l-lactic acid with high optical activity and a soil amendment with food waste that demonstrates plant growth promoting activity.

    Science.gov (United States)

    Kitpreechavanich, Vichien; Hayami, Arisa; Talek, Anfal; Chin, Clament Fui Seung; Tashiro, Yukihiro; Sakai, Kenji

    2016-07-01

    A unique method to produce highly optically-active l-lactic acid and soil amendments that promote plant growth from food waste was proposed. Three Bacillus strains Bacillus subtilis KBKU21, B. subtilis N3-9 and Bacillus coagulans T27, were used. Strain KBKU21 accumulated 36.9 g/L l-lactic acid with 95.7% optical activity and 98.2% l-lactic acid selectivity when fermented at 43°C for 84 h in a model kitchen refuse (MKR) medium. Residual precipitate fraction (anaerobically-fermented MKR (AFM) compost) analysis revealed 4.60%, 0.70% and 0.75% of nitrogen (as N), phosphorous (as P2O5), and potassium (as K2O), respectively. Additionally, the carbon to nitrogen ratio decreased from 13.3 to 10.6. AFM compost with KBKU21 promoted plant growth parameters, including leaf length, plant height and fresh weight of Brassica rapa (Komatsuna), than that by chemical fertilizers or commercial compost. The concept provides an incentive for the complete recycling of food waste, contributing towards a sustainable production system.

  16. Force-activated substrates for high-precision, high-throughput optical trapping assays of ssDNA motor proteins (Conference Presentation)

    Science.gov (United States)

    Okoniewski, Stephen; Perkins, Thomas T.

    2016-09-01

    Optical-trapping-based assays can measure individual proteins bind to and move along DNA with sub-nm resolution, and have yielded insight into a broad array of protein-DNA interactions. Unfortunately, collecting large numbers of high-resolution traces remains an ongoing challenge. Studying helicase motion along DNA exemplifies this challenge. One major difficulty is that helicase binding often requires a single stranded (ss)-double stranded (ds) DNA junction flanked by ssDNA with a minimum size and orientation. Historically, creating such DNA substrates is inefficient. More problematic is that data throughput is low in standard surface-based assays since all substrates are unwound upon introduction of ATP. The net result is 2-4 high-resolution traces on a good day. To improve throughput, we sought to turn-on or activate a substrate for a helicase one molecule at a time and thereby sequentially study many molecules on an individual microscope slide. As a first step towards this goal, we engineered a dsDNA that contains two site-specific nicks along the same strand of the dsDNA but no ssDNA. Upon overstretching the DNA (F = 65 pN), the strand between the two nicks was mechanically dissociated. We demonstrated this with two different substrates: one yielding an internal ssDNA region of 1100 nt and the other yielding a 20-bp long hairpin flanked by 30 nt of ssDNA. Unwinding a hairpin yields a 3-fold larger signal while the 30-nt ssDNA serves as the binding site for the helicase. We expect that these force-activated substrates to significantly accelerate high-resolution optical-trapping studies of DNA helicases.

  17. Quasi-optical active antennas

    Science.gov (United States)

    Moussessian, Alina

    Quasi-optical power combiners such as quasi-optical grids provide an efficient means of combining the output power of many solid-state devices in free space. Unlike traditional power combiners no transmission lines are used, therefore, high output powers with less loss can be achieved at higher frequencies. This thesis investigates four different active antenna grids. The first investigation is into X-band High Electron Mobility Transistor (HEMT) grid amplifiers. Modelling and stability issues of these grids are discussed, and gain and power measurements are presented. A grid amplifier with a maximum efficiency of 22.5% at 10 GHz and a peak gain of 11dB is presented. The second grid is a varactor grid used as a positive feedback network for a grid amplifier to construct a tunable grid oscillator. Reflection measurements for the varactor grid show a tuning range of 1.2 GHz. The third grid is a self- complementary grid amplifier. The goal is to design a new amplifier with a unit cell structure that can be directly modelled using CAD tools. The properties of self- complementary structures are studied and used in the design of this new amplifier grid. The fourth grid is a 12 x 12 terahertz Schottky grid frequency doubler with a measured output power of 24 mW at 1 THz for 3.1-μs 500-GHz input pulses with a peak power of 47 W. A passive millimeter-wave travelling-wave antenna built on a dielectric substrate is also presented. Calculations indicate that the antenna has a gain of 15 dB with 3-dB beamwidths of 10o in the H-plane and 64o in the E-plane. Pattern measurements at 90 GHz support the theory. The antenna is expected to have an impedance in the range of 50/Omega to 80/Omega.

  18. The Adaptive Optics Summer School Laboratory Activities

    CERN Document Server

    Ammons, S Mark; Armstrong, J D; Crossfield, Ian; Do, Tuan; Fitzgerald, Mike; Harrington, David; Hickenbotham, Adam; Hunter, Jennifer; Johnson, Jess; Johnson, Luke; Li, Kaccie; Lu, Jessica; Maness, Holly; Morzinski, Katie; Norton, Andrew; Putnam, Nicole; Roorda, Austin; Rossi, Ethan; Yelda, Sylvana

    2011-01-01

    Adaptive Optics (AO) is a new and rapidly expanding field of instrumentation, yet astronomers, vision scientists, and general AO practitioners are largely unfamiliar with the root technologies crucial to AO systems. The AO Summer School (AOSS), sponsored by the Center for Adaptive Optics, is a week-long course for training graduate students and postdoctoral researchers in the underlying theory, design, and use of AO systems. AOSS participants include astronomers who expect to utilize AO data, vision scientists who will use AO instruments to conduct research, opticians and engineers who design AO systems, and users of high-bandwidth laser communication systems. In this article we describe new AOSS laboratory sessions implemented in 2006-2009 for nearly 250 students. The activity goals include boosting familiarity with AO technologies, reinforcing knowledge of optical alignment techniques and the design of optical systems, and encouraging inquiry into critical scientific questions in vision science using AO sys...

  19. Different ways to active optical frequency standards

    Science.gov (United States)

    Pan, Duo; Xue, Xiaobo; Zhang, Xiaogang; Chen, Jingbiao

    2016-06-01

    Active optical frequency standard, or active optical clock, is a new concept of optical frequency standard, where a weak feedback with phase coherence information in optical bad-cavity limitation is formed, and the continuous self-sustained coherent stimulated emission between two atomic transition levels with population inversion is realized. Through ten years of both theoretical and experimental exploration, the narrow linewidth and suppression of cavity pulling effect of active optical frequency standard have been initially proved. In this paper, after a simple review, we will mainly present the most recent experimental progresses of active optical frequency standards in Peking University, including 4-level cesium active optical frequency standards and active Faraday optical frequency standards. The future development of active optical frequency standards is also discussed.

  20. Actively Pumped Faraday Optical Filter

    Science.gov (United States)

    1996-04-30

    Richard I. Billmers Vincent M. Contarino David M. Allocca Martin F. Squicciarini William J. Scharpf 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...States Patent [i9] Billmers et al. iiiiiiifflimi iilliiiiiii US005513032A [ii] Patent Number: [45] Date of Patent: 5,513,032 Apr. 30, 1996...54] ACTIVELY PUMPED FARADAY OPTICAL FILTER [75] Inventors: Richard I. Billmers , Bensalem; Vincent M. Contarino, Warrington; David M

  1. Human psychophysiological activity monitoring methods using fiber optic sensors

    Science.gov (United States)

    Zyczkowski, M.; Uzieblo-Zyczkowska, B.

    2010-10-01

    The paper presents the concept of fiber optic sensor system for human psycho-physical activity detection. A fiber optic sensor that utilizes optical phase interferometry or intensity in modalmetric to monitor a patient's vital signs such as respiration cardiac activity, blood pressure and body's physical movements. The sensor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acusto-mechanical signals from the patient are coupled into the optical fiber. The system can be implemented in embodiments ranging form a low cost in-home to a high end product for in hospital use.

  2. High-Temperature Optical Sensor

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  3. Active optics with a minimum number of actuators

    Science.gov (United States)

    Lemaitre, Gerard R.

    2014-06-01

    Optics for astronomy implies powerful developments of active and adaptive optics methods applied to instrumentation from X-rays to the near infrared for the design of telescopes, spectrographs, and coronagraph planet finders. This presentation particularly emphasizes the development of active optics methods. Highly accurate and remarkably smooth surfaces from active optics methods allow new optical systems that use highly aspheric and non-axisymmetric - freeform - surfaces. Depending on the goal and performance required for a deformable optical surface, elasticity theory analysis is carried out either with small deformation thin plate theory, large deformation thin plate theory, shallow spherical shell theory, or the weakly conical shell theory. A mirror thickness distribution is then determined as a function of associated bending actuators and boundary conditions. For a given optical shape to generate, one searches for optical solutions with a minimum number of actuators.

  4. Optics assembly for high power laser tools

    Science.gov (United States)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  5. Optics assembly for high power laser tools

    Energy Technology Data Exchange (ETDEWEB)

    Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

    2016-06-07

    There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

  6. International Standardization Activities for Optical Amplifiers

    Institute of Scientific and Technical Information of China (English)

    Haruo Okamura

    2003-01-01

    International standardization activities for Optical Amplifiers at IECTC86 and ITU-T SG15 are reviewed. Current discussions include Optical Amplifier safety guideline, Reliability standard, Rest methods of Noise and PMD, Definitions of Raman amplifier parameters and OA classification.

  7. Active optical zoom for space-based imaging

    Science.gov (United States)

    Wick, David V.; Bagwell, Brett E.; Sweatt, William C.; Peterson, Gary L.; Martinez, Ty; Restaino, Sergio R.; Andrews, Jonathan R.; Wilcox, Christopher C.; Payne, Don M.; Romeo, Robert

    2006-08-01

    The development of sensors that are compact, lighter weight, and adaptive is critical for the success of future military initiatives. Space-based systems need the flexibility of a wide FOV for surveillance while simultaneously maintaining high-resolution for threat identification and tracking from a single, nonmechanical imaging system. In order to meet these stringent requirements, the military needs revolutionary alternatives to conventional imaging systems. We will present recent progress in active optical (aka nonmechanical) zoom for space applications. Active optical zoom uses multiple active optics elements to change the magnification of the imaging system. In order to optically vary the magnification of an imaging system, continuous mechanical zoom systems require multiple optical elements and use fine mechanical motion to precisely adjust the separations between individual or groups of elements. By incorporating active elements into the optical design, we have designed, demonstrated, and patented imaging systems that are capable of variable optical magnification with no macroscopic moving parts.

  8. High pressure optical combustion probe

    Energy Technology Data Exchange (ETDEWEB)

    Woodruff, S.D.; Richards, G.A.

    1995-06-01

    The Department of Energy`s Morgantown Energy Technology Center has developed a combustion probe for monitoring flame presence and heat release. The technology involved is a compact optical detector of the OH radical`s UV fluorescence. The OH Monitor/Probe is designed to determine the flame presence and provide a qualitative signal proportional to the flame intensity. The probe can be adjusted to monitor a specific volume in the combustion zone to track spatial fluctuations in the flame. The probe is capable of nanosecond time response and is usually slowed electronically to fit the flame characteristics. The probe is a sapphire rod in a stainless steel tube which may be inserted into the combustion chamber and pointed at the flame zone. The end of the sapphire rod is retracted into the SS tube to define a narrow optical collection cone. The collection cone may be adjusted to fit the experiment. The fluorescence signal is collected by the sapphire rod and transmitted through a UV transmitting, fused silica, fiber optic to the detector assembly. The detector is a side window photomultiplier (PMT) with a 310 run line filter. A Hamamatsu photomultiplier base combined with a integral high voltage power supply permits this to be a low voltage device. Electronic connections include: a power lead from a modular DC power supply for 15 VDC; a control lead for 0-1 volts to control the high voltage level (and therefore gain); and a lead out for the actual signal. All low voltage connections make this a safe and easy to use device while still delivering the sensitivity required.

  9. Baker's Yeast Mediated Reduction of Optically Active Diketone

    Institute of Scientific and Technical Information of China (English)

    ZHENG, Guo-Jun(郑国君); GAO, Xiao-Lei(高晓蕾); CHEN, Jin-Chun(陈锦春); LI, Yu-Lin(李裕林)

    2004-01-01

    Baker's yeast mediated reduction of optically active diketone is described. The two keto groups are efficiently differentiated and the ee value of the recovered material is considerably raised. It affords highly optically active key intermediates efficiently for the synthesis of natural polyhydroxylated agarofuran products.

  10. Production of high optical purity l-lactic acid from waste activated sludge by supplementing carbohydrate: effect of temperature and pretreatment time.

    Science.gov (United States)

    Jian, Qiwei; Li, Xiang; Chen, Yinguang; Liu, Yanan; Pan, Yin

    2016-10-01

    It has been widely accepted that the most environmentally beneficial way to treat waste activated sludge (WAS), the byproduct of municipal wastewater treatment plant, is to recover the valuable organic acid. However, the bio-conversion of lactic acid, one of the high added-value chemical, is seldom reported from WAS fermentation. In this paper, l-lactic acid was observed dominant in the WAS fermentation liquid with carbohydrate addition at ambient temperature. Furthermore, the effect of temperature on l-lactic acid and d-lactic acid production was fully discussed: two isomers were rapidly produced and consumed up in one day at mesophilic condition; and almost optically pure l-lactic acid was generated at thermophilic condition, yet time-consuming with yield of l-lactic acid enhancing by 52.9% compared to that at ambient temperature. The study mechanism showed that mesophilic condition was optimal for both production and consumption of l-lactic acid and d-lactic acid, while consumption of l-lactic acid and production of d-lactic acid were severely inhibited at thermophilic condition. Therefore, by maintaining thermophilic for 4 h in advance and subsequently fermenting mesophilic for 34 h, the concentration of l-lactic acid with optical activity of 98.3% was improved to 16.6 ± 0.5 g COD/L at a high specific efficiency of 0.6097/d.

  11. Evolution of the optical and hard X-ray activity of AM Her in a season dominated by the high states

    Science.gov (United States)

    Šimon, Vojtěch

    2016-07-01

    The long-term activity of AM Her, the prototype of polars, consists of interchanging high and low states. This analysis uses the data from the BAT/ Swift, MAXI/ ISS, and AAVSO data archives (including long CCD V-band night series) for investigating the relation of the time evolution of intensities in the hard X-ray, medium/hard X-ray, and the optical bands on super-orbital timescale in a season dominated by the long high-state episodes. The observations mapped the relation of the cyclotron and bremsstrahlung luminosities in such episodes. Although an increase of intensity of the cyclotron emission is generally accompanied by a brightening of the bremsstrahlung component, this relation differs for the individual high-state episodes. These variations were accompanied by the large changes of the optical modulation. In my view, all of these variations suggest variations of the dimensions and structure of the cyclotron emitting region(s), not only the changes of the mass accretion rate. The activity during a decline (much less steep than the state transition) from an initial very bright peak can be explained by a gradual evolution of the conditions in stratified shock regions in a single high state episode. The observed behavior in the neighboring high-state episodes is also important for explaining the mechanisms which cause the low state between them. In the interpretation, some low-state episodes cause that AM Her develops a different accretion mode than the one before entering the low state. Each high-state episode is a complex phenomenon in the history of accretion in this system.

  12. High-power optics lasers and applications

    CERN Document Server

    Apollonov, Victor V

    2015-01-01

    This book covers the basics, realization and materials for high power laser systems and high power radiation interaction with  matter. The physical and technical fundamentals of high intensity laser optics and adaptive optics and the related physical processes in high intensity laser systems are explained. A main question discussed is: What is power optics? In what way is it different from ordinary optics widely used in cameras, motion-picture projectors, i.e., for everyday use? An undesirable consequence of the thermal deformation of optical elements and surfaces was discovered during studies of the interaction with powerful incident laser radiation. The requirements to the fabrication, performance and quality of optical elements employed within systems for most practical applications are also covered. The high-power laser performance is generally governed by the following: (i) the absorption of incident optical radiation (governed primarily by various absorption mechanisms), (ii) followed by a temperature ...

  13. Active materials for integrated optic applications

    Science.gov (United States)

    Hayden, Joseph S.; Funk, David S.; Veasey, David L.; Peters, Philip M.; Sanford, Norman A.

    1999-11-01

    The ability to engineer glass properties through the selection and adjustment of chemical composition continues to make glass a leading material in both active and passive applications. The development of optimal glass compositions for integrated optical applications requires a number of considerations that are often at variance with one another. Of critical importance is that the glass offers compatibility with standard ion exchange technologies, allowing fabrication of guided wave structures. In addition, for application as an active material, the resultant structures must be characterized by absence of inclusions and low absorption at the lasing wavelength, putting demands on both the selection and identity of the raw materials used to prepare the glass. We report on the development of an optimized glass composition for integrated optic applications that combines good laser properties with good chemical durability allowing for a wide range of chemical processing steps to be employed without substrate deterioration. In addition, care was taken during the development of this glass to insure that the selected composition was consistent with manufacturing technology for producing high optical quality glass. We present the properties of the resultant glasses, including results of detailed chemical and laser properties, for use in the design and modeling of active waveguides prepared with these glasses.

  14. Optical Activity of Planar Achiral Metamaterials

    CERN Document Server

    Plum, E; Zheludev, N I

    2008-01-01

    We report that the classical phenomena of optical activity and circular dichroism, which are traditionally associated with chirality (helicity) of organic molecules, proteins and inorganic structures, can be observed in non-chiral artificial media. Intriguingly, our metamaterial structure yields exceptionally strong resonant optical activity, which also leads to the appearance of a backward wave, a characteristic sign of negative-index media.

  15. Section on High Resolution Optical Imaging (HROI)

    Data.gov (United States)

    Federal Laboratory Consortium — The Section on High Resolution Optical Imaging (HROI) develops novel technologies for studying biological processes at unprecedented speed and resolution. Research...

  16. Optical magnetism and optical activity in nonchiral planar plasmonic metamaterials.

    Science.gov (United States)

    Li, Guozhou; Li, Qiang; Yang, Lizhen; Wu, Lijun

    2016-07-01

    We investigate optical magnetism and optical activity in a simple planar metamolecule composed of double U-shaped metal split ring resonators (SRRs) twisted by 90° with respect to one another. Compared to a single SRR, the resonant energy levels are split and strong magnetic response can be observed due to inductive and conductive coupling. More interestingly, the nonchiral structures exhibit strong optical gyrotropy (1100°/λ) under oblique incidence, benefiting from the strong electromagnetic coupling. A chiral molecule model is proposed to shed light on the physical origin of optical activity. These artificial chiral metamaterials could be utilized to control the polarization of light and promise applications in enantiomer sensing-based medicine, biology, and drug development.

  17. Efficient Synthesis of Optically Active Alcohols

    Institute of Scientific and Technical Information of China (English)

    J.S. Chen; Z.R. Dong; Y.Y. Li; B.Z. Li; Y. Xing; W.Y. Shen; G. Chen; X.Q. Zhang; J. X. Gao

    2005-01-01

    @@ 1Introduction Optically active secondary alcohols are versatile building blocks for synthesis of unnatural biological active compounds and functional materials. Therefore, study on efficient synthesis of optically active alcohols is becoming an important subject in synthetic organic chemistry. Catalytic asymmetric reduction of carbonyl compounds is a practical method to create chiral alcohols. For the past decades, a large number of catalytic methods have been developed to achieve this goal.

  18. Semiconductor optical amplifier-based all-optical gates for high-speed optical processing

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    2000-01-01

    Semiconductor optical amplifiers are useful building blocks for all-optical gates as wavelength converters and OTDM demultiplexers. The paper reviews the progress from simple gates using cross-gain modulation and four-wave mixing to the integrated interferometric gates using cross-phase modulation....... These gates are very efficient for high-speed signal processing and open up interesting new areas, such as all-optical regeneration and high-speed all-optical logic functions...

  19. An optical fan for light beams for high-precision optical measurements and optical switching

    CERN Document Server

    Zhou, Zhi-Yuan; Ding, Dong-Sheng; Jiang, Yun-Kun; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2014-01-01

    The polarization and orbital angular momentum properties of light are of great importance in optical science and technology in the fields of high precision optical measurements and high capacity and high speed optical communications. Here we show, a totally new method, based on a combination of these two properties and using the thermal dispersion and electro-optical effect of birefringent crystals, the construction of a simple and robust scheme to rotate a light beam like a fan. Using a computer-based digital image processing technique, we determine the temperature and the thermal dispersion difference of the crystal with high resolution. We also use the rotation phenomenon to realize thermo-optic and electro-optic switches. The basic operating principles for measurement and switching processes are presented in detail. The methods developed here will have wide practical applicability in various fields, including remote sensing, materials science and optical communication networks.

  20. Optically active mechanical modes of tapered optical fibers

    CERN Document Server

    Wuttke, Chrisitan; Rauschenbeutel, Arno

    2013-01-01

    Tapered optical fibers with a nanofiber waist are widely used tools for efficient coupling of light to photonic devices or quantum emitters via the nanofiber's evanescent field. In order to ensure well-controlled coupling, the phase and polarization of the nanofiber guided light field have to be stable. Here, we show that in typical tapered optical fibers these quantities exhibit high-frequency thermal fluctuations. They originate from high-Q torsional oscillations that opto-mechanically couple to the nanofiber-guided light. We present a simple ab-initio theoretical model that quantitatively explains the torsional mode spectrum and that can be used to design tapered optical fibers with tailored mechanical properties.

  1. Chiral THz metamaterial with tunable optical activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jiangfeng [Los Alamos National Laboratory; Taylor, Antoinette [Los Alamos National Laboratory; O' Hara, John [Los Alamos National Laboratory; Chowdhury, Roy [Los Alamos National Laboratory; Zhao, Rongkuo [IOWA STATE UNIV; Soukoullis, Costas M [IOWA STATE UNIV

    2010-01-01

    Optical activity in chiral metamaterials is demonstrated in simulation and shows actively tunable giant polarization rotation at THz frequencies. Electric current distributions show that pure chirality is achieved by our bi-Iayer chiral metamaterial design. The chirality can be optically controlled by illumination with near-infrared light. Optical activity, occurring in chiral materials such as DNA, sugar and many other bio-molecules, is a phenomenon of great importance to many areas of science including molecular biology, analytical chemistry, optoelectronics and display applications. This phenomenon is well understood at an effective medium level as a magnetic/electric moment excited by the electric/magnetic field of the incident electromagnetic (EM) wave. Usually, natural chiral materials exhibit very weak optical activity e.g. a gyrotropic quartz crystal. The optical activity of chiral metamaterials, however, can be five orders of magnitude stronger. Chiral metamaterials are made of sub-wavelength resonators lacking symmetry planes. The asymmetry allows magnetic moments to be excited by the electric field of the incident EM wave and vice versa. Recently, chiral metamaterials have been demonstrated and lead to prospects in giant optical activity, circular dichroism, negative refraction and reversing the Casmir force. These fascinating optical properties require strong chirality, which may be designed through the microscopic structure of chiral metamaterials. However, these metamaterials have a fixed response function, defined by the geometric structuring, which limits their ability to manipulate EM waves. Active metamaterials realize dynamic control of response functions and have produced many influential applications such as ultra-fast switching devices, frequency and phase modulation and memory devices. Introducing active designs to chiral metamaterials will give additional freedom in controlling the optical activity, and therefore enable dynamic manipulation

  2. Optical changes in cortical tissue during seizure activity using optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Ornelas, Danielle; Hasan, Md.; Gonzalez, Oscar; Krishnan, Giri; Szu, Jenny I.; Myers, Timothy; Hirota, Koji; Bazhenov, Maxim; Binder, Devin K.; Park, Boris H.

    2017-02-01

    Epilepsy is a chronic neurological disorder characterized by recurrent and unpredictable seizures. Electrophysiology has remained the gold standard of neural activity detection but its resolution and high susceptibility to noise and motion artifact limit its efficiency. Optical imaging techniques, including fMRI, intrinsic optical imaging, and diffuse optical imaging, have also been used to detect neural activity yet these techniques rely on the indirect measurement of changes in blood flow. A more direct optical imaging technique is optical coherence tomography (OCT), a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. In this study, OCT was used to detect non-vascular depth-dependent optical changes in cortical tissue during 4-aminopyridine (4-AP) induced seizure onset. Calculations of localized optical attenuation coefficient (µ) allow for the assessment of depth-resolved volumetric optical changes in seizure induced cortical tissue. By utilizing the depth-dependency of the attenuation coefficient, we demonstrate the ability to locate and remove the optical effects of vasculature within the upper regions of the cortex on the attenuation calculations of cortical tissue in vivo. The results of this study reveal a significant depth-dependent decrease in attenuation coefficient of nonvascular cortical tissue both ex vivo and in vivo. Regions exhibiting decreased attenuation coefficient show significant temporal correlation to regions of increased electrical activity during seizure onset and progression. This study allows for a more thorough and biologically relevant analysis of the optical signature of seizure activity in vivo using OCT.

  3. LDEF active optical system components experiment

    Science.gov (United States)

    Blue, M. D.

    1992-01-01

    A preliminary report on the Active Optical System Components Experiment is presented. This experiment contained 136 components in a six inch deep tray including lasers, infrared detectors and arrays, ultraviolet light detectors, light-emitting diodes, a light modulator, flash lamps, optical filters, glasses, and samples of surface finishes. Thermal, mechanical, and structural considerations leading to the design of the tray hardware are discussed. In general, changes in the retested component characteristics appear as much related to the passage of time as to the effects of the space environment, but organic materials, multilayer optical interference filters, and extreme-infrared reflectivity of black paints show unexpected changes.

  4. Synthesis of Optically Active trans-2-Aminocyclopropane-carboxylic Esters

    Institute of Scientific and Technical Information of China (English)

    Jiang Chun ZHONG; Shang Zhong LIU; Qing Hua BIAN; Ming Ming YIN; Min WANG

    2006-01-01

    Two new optically active trans-2-aminocyclopropanecarboxylic esters (β-ACCs) of optical purity 91%-96% were concisely synthesized via ozonization, oxidation, Curtius rearrangement from commercial available optically active trans-chrysanthemate in total yield 36%.

  5. Photovoltaic concentrator assembly with optically active cover

    Science.gov (United States)

    Plesniak, Adam P

    2014-01-21

    A photovoltaic concentrator assembly that includes a housing that defines an internal volume and includes a rim, wherein the rim defines an opening into the internal volume, a photovoltaic cell positioned in the internal volume, and an optical element that includes an optically active body and a flange extending outward from the body, wherein the flange is sealingly engaged with the rim of the housing to enclose the internal volume.

  6. Actively heated high-resolution fiber-optic-distributed temperature sensing to quantify streambed flow dynamics in zones of strong groundwater upwelling

    Science.gov (United States)

    Briggs, Martin A.; Buckley, Sean F.; Bagtzoglou, Amvrossios C.; Werkema, Dale D.; Lane, John W.

    2016-07-01

    Zones of strong groundwater upwelling to streams enhance thermal stability and moderate thermal extremes, which is particularly important to aquatic ecosystems in a warming climate. Passive thermal tracer methods used to quantify vertical upwelling rates rely on downward conduction of surface temperature signals. However, moderate to high groundwater flux rates (>-1.5 m d-1) restrict downward propagation of diurnal temperature signals, and therefore the applicability of several passive thermal methods. Active streambed heating from within high-resolution fiber-optic temperature sensors (A-HRTS) has the potential to define multidimensional fluid-flux patterns below the extinction depth of surface thermal signals, allowing better quantification and separation of local and regional groundwater discharge. To demonstrate this concept, nine A-HRTS were emplaced vertically into the streambed in a grid with ˜0.40 m lateral spacing at a stream with strong upward vertical flux in Mashpee, Massachusetts, USA. Long-term (8-9 h) heating events were performed to confirm the dominance of vertical flow to the 0.6 m depth, well below the extinction of ambient diurnal signals. To quantify vertical flux, short-term heating events (28 min) were performed at each A-HRTS, and heat-pulse decay over vertical profiles was numerically modeled in radial two dimension (2-D) using SUTRA. Modeled flux values are similar to those obtained with seepage meters, Darcy methods, and analytical modeling of shallow diurnal signals. We also observed repeatable differential heating patterns along the length of vertically oriented sensors that may indicate sediment layering and hyporheic exchange superimposed on regional groundwater discharge.

  7. High Spectral Density Optical Communication Technologies

    CERN Document Server

    Nakazawa, Masataka; Miyazaki, Tetsuya

    2010-01-01

    The latest hot topics of high-spectral density optical communication systems using digital coherent optical fibre communication technologies are covered by this book. History and meaning of a "renaissance" of the technology, requirements to the Peta-bit/s class "new generation network" are also covered in the first part of this book. The main topics treated are electronic and optical devices, digital signal processing including forward error correction, modulation formats as well as transmission and application systems. The book serves as a reference to researchers and engineers.

  8. Optically active quantum-dot molecules.

    Science.gov (United States)

    Shlykov, Alexander I; Baimuratov, Anvar S; Baranov, Alexander V; Fedorov, Anatoly V; Rukhlenko, Ivan D

    2017-02-20

    Chiral molecules made of coupled achiral semiconductor nanocrystals, also known as quantum dots, show great promise for photonic applications owing to their prospective uses as configurable building blocks for optically active structures, materials, and devices. Here we present a simple model of optically active quantum-dot molecules, in which each of the quantum dots is assigned a dipole moment associated with the fundamental interband transition between the size-quantized states of its confined charge carriers. This model is used to analytically calculate the rotatory strengths of optical transitions occurring upon the excitation of chiral dimers, trimers, and tetramers of general configurations. The rotatory strengths of such quantum-dot molecules are found to exceed the typical rotatory strengths of chiral molecules by five to six orders of magnitude. We also study how the optical activity of quantum-dot molecules shows up in their circular dichroism spectra when the energy gap between the molecular states is much smaller than the states' lifetime, and maximize the strengths of the circular dichroism peaks by optimizing orientations of the quantum dots in the molecules. Our analytical results provide clear design guidelines for quantum-dot molecules and can prove useful in engineering optically active quantum-dot supercrystals and photonic devices.

  9. Optics of high-performance electron microscopes*

    OpenAIRE

    H H Rose

    2016-01-01

    During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by...

  10. Active Optical Fibers Doped with Ceramic Nanocrystals

    Directory of Open Access Journals (Sweden)

    Jan Mrazek

    2014-01-01

    Full Text Available Erbium-doped active optical fiber was successfully prepared by incorporation of ceramic nanocrystals inside a core of optical fiber. Modified chemical vapor deposition was combined with solution-doping approach to preparing preform. Instead of inorganic salts erbium-doped yttrium-aluminium garnet nanocrystals were used in the solution-doping process. Prepared preform was drawn into single-mode optical fiber with a numerical aperture 0.167. Optical and luminescence properties of the fiber were analyzed. Lasing ability of prepared fiber was proofed in a fiber-ring set-up. Optimal laser properties were achieved for a fiber length of 20~m. The slope efficiency of the fiber-laser was about 15%. Presented method can be simply extended to the deposition of other ceramic nanomaterials.

  11. Spontaneous natural optical activity in disordered media

    CERN Document Server

    Pinheiro, F A; Papasimakis, N; Zheludev, N I

    2016-01-01

    We demonstrate natural optical activity in disordered ensembles of non-chiral plasmonic resonators. We show that the statistical distributions of rotatory power and spatial dichroism are strongly dependent on the scattering mean free path in diffusive random media. This result is explained in terms of the intrinsic geometric chirality of disordered media, as they lack mirror symmetry. We argue that chirality and natural optical activity of disordered systems can be quantified by the standard deviation of both rotatory power and spatial dichroism. Our results are based on microscopic electromagnetic wave transport theory coupled to vectorial Green's matrix method for pointlike scatterers, and are independently confirmed by full-wave simulations.

  12. High-speed signal processing using highly nonlinear optical fibres

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Oxenløwe, Leif Katsuo; Mulvad, Hans Christian Hansen

    2009-01-01

    relying on the phase of the optical field. Topics covered include all-optical switching of 640 Gbit/s and 1.28 Tbit/s serial data, wavelength conversion at 640 Gbit/s, optical amplitude regeneration of differential phase shift keying (DPSK) signals, as well as midspan spectral inversion for differential 8......We review recent progress in all-optical signal processing techniques making use of conventional silica-based highly nonlinear fibres. In particular, we focus on recent demonstrations of ultra-fast processing at 640 Gbit/s and above, as well as on signal processing of novel modulation formats...

  13. Detection of cortical optical changes during seizure activity using optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Ornelas, Danielle; Hasan, Md.; Gonzalez, Oscar; Krishnan, Giri; Szu, Jenny I.; Myers, Timothy; Hirota, Koji; Bazhenov, Maxim; Binder, Devin K.; Park, Boris H.

    2017-02-01

    Electrophysiology has remained the gold standard of neural activity detection but its resolution and high susceptibility to noise and motion artifact limit its efficiency. Imaging techniques, including fMRI, intrinsic optical imaging, and diffuse optical imaging, have been used to detect neural activity, but rely on indirect measurements such as changes in blood flow. Fluorescence-based techniques, including genetically encoded indicators, are powerful techniques, but require introduction of an exogenous fluorophore. A more direct optical imaging technique is optical coherence tomography (OCT), a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. In this study, we sought to examine non-vascular depth-dependent optical changes directly related to neural activity. We used an OCT system centered at 1310 nm to search for changes in an ex vivo brain slice preparation and an in vivo model during 4-AP induced seizure onset and propagation with respect to electrical recording. By utilizing Doppler OCT and the depth-dependency of the attenuation coefficient, we demonstrate the ability to locate and remove the optical effects of vasculature within the upper regions of the cortex from in vivo attenuation calculations. The results of this study show a non-vascular decrease in intensity and attenuation in ex vivo and in vivo seizure models, respectively. Regions exhibiting decreased optical changes show significant temporal correlation to regions of increased electrical activity during seizure. This study allows for a thorough and biologically relevant analysis of the optical signature of seizure activity both ex vivo and in vivo using OCT.

  14. Preliminary optical design of an Active Optics test bench for space applications.

    Science.gov (United States)

    Calcines, A.; Bitenc, U.; Rolt, S.; Reeves, S.; Doelman, N.; Human, J.; Morris, T.; Myers, R.; Talbot, G.

    2017-03-01

    This communication presents a preliminary optical design for a test bench conceived within the European Space Agency's TRP project (Active Optics Correction Chain (AOCC) for large monolithic mirrors) with the goal of designing and developing an Active Optics system able to correct in space on telescopes apertures larger than 3 meters. The test bench design uses two deformable mirrors of 37.5 mm and 116 mm, the smallest mirror to generate aberrations and the largest one to correct them. The system is configured as a multi-functional test bench capable of verifying the performance of a Shack-Hartmann wavefront sensor as well as of a Phase Diversity based wavefront sensor. A third optical path leads to a high-order Shack-Hartmann wavefront sensor to monitor the entire system performance.

  15. Technology Development for High Efficiency Optical Communications

    Science.gov (United States)

    Farr, William H.

    2012-01-01

    Deep space optical communications is a significantly more challenging operational domain than near Earth space optical communications, primarily due to effects resulting from the vastly increased range between transmitter and receiver. The NASA Game Changing Development Program Deep Space Optical Communications Project is developing four key technologies for the implementation of a high efficiency telecommunications system that will enable greater than 10X the data rate of a state-of-the-art deep space RF system (Ka-band) for similar transceiver mass and power burden on the spacecraft. These technologies are a low mass spacecraft disturbance isolation assembly, a flight qualified photon counting detector array, a high efficiency flight laser amplifier and a high efficiency photon counting detector array for the ground-based receiver.

  16. Optically transparent high temperature shape memory polymers.

    Science.gov (United States)

    Xiao, Xinli; Qiu, Xueying; Kong, Deyan; Zhang, Wenbo; Liu, Yanju; Leng, Jinsong

    2016-03-21

    Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450-800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles.

  17. Surface enhanced Raman optical activity (SEROA)

    DEFF Research Database (Denmark)

    Abdali, Salim; Blanch, E.W.

    2008-01-01

    Raman optical activity (ROA) directly monitors the stereochemistry of chiral molecules and is now an incisive probe of biomolecular structure. ROA spectra contain a wealth of information on tertiary folding, secondary structure and even the orientation of individual residues in proteins and nucleic...

  18. High Optical Access Trap 2.0.

    Energy Technology Data Exchange (ETDEWEB)

    Maunz, Peter Lukas Wilhelm [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-26

    The High Optical Access (HOA) trap was designed in collaboration with the Modular Universal Scalable Ion-trap Quantum Computer (MUSIQC) team, funded along with Sandia National Laboratories through IARPA's Multi Qubit Coherent Operations (MQCO) program. The design of version 1 of the HOA trap was completed in September 2012 and initial devices were completed and packaged in February 2013. The second version of the High Optical Access Trap (HOA-2) was completed in September 2014 and is available at IARPA's disposal.

  19. FTTA System Demo Using Optical Fiber-Coupled Active Antennas

    Directory of Open Access Journals (Sweden)

    Niels Neumann

    2014-08-01

    Full Text Available The convergence of optical and wireless systems such as Radio-over-Fiber (RoF networks is the key to coping with the increasing bandwidth demands due to the increasing popularity of video and other high data rate applications. A high level of integration of optical technologies enables simple base stations with a fiber-to-the-antenna (FTTA approach. In this paper, we present a complete full-duplex RoF–FTTA system consisting of integrated active fiber-coupled optical receiving and transmitting antennas that are directly connected to a standard single mode fiber optical link. Data rates up to 1 Gbit/s could be shown without advanced modulation formats on a 1.5 GHz carrier frequency. The antennas as well as the whole system are explained and the results of the system experiments are discussed.

  20. Active learning in optics and photonics

    Science.gov (United States)

    Niemela, Joseph J.

    2016-09-01

    Active learning in optics and photonics (ALOP) is a program of the International Basic Sciences Program at UNESCO, in collaboration with the Abdus Salam International Centre for Theoretical Physics (ICTP) and supported by SPIE, which is designed to help teachers in the developing world attract and retain students in the physical sciences. Using optics and photonics, it naturally attracts the interest of students and can be implemented using relatively low cost technologies, so that it can be more easily reproduced locally. The active learning methodology is student-centered, meaning the teachers give up the role of lecturer in favor of guiding and facilitating a learning process in which students engage in hands-on activities and active peer-peer discussions, and is shown to effectively enhance basic conceptual understanding of physics.

  1. Advanced Functionalities for Highly Reliable Optical Networks

    DEFF Research Database (Denmark)

    An, Yi

    This thesis covers two research topics concerning optical solutions for networks e.g. avionic systems. One is to identify the applications for silicon photonic devices for cost-effective solutions in short-range optical networks. The other one is to realise advanced functionalities in order to in......) using two exclusive OR (XOR) gates realised by four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is experimentally demonstrated and very low (~ 1 dB) total operation penalty is achieved....... to increase the availability of highly reliable optical networks. A cost-effective transmitter based on a directly modulated laser (DML) using a silicon micro-ring resonator (MRR) to enhance its modulation speed is proposed, analysed and experimentally demonstrated. A modulation speed enhancement from 10 Gbit...... interconnects and network-on-chips. A novel concept of all-optical protection switching scheme is proposed, where fault detection and protection trigger are all implemented in the optical domain. This scheme can provide ultra-fast establishment of the protection path resulting in a minimum loss of data...

  2. High performance fluoride optical coatings for DUV optics

    Science.gov (United States)

    Zhang, Lichao; Cai, Xikun

    2014-08-01

    In deep ultraviolet region that typical applications are used on the ArF wavelength, coated optics should meet stringent requirements of optical systems. To meet these requirements, systematical researches are carried out on fabrication and characterization methods of fluoride coatings. First, by optimizing of deposition processes, dense coatings with the refractive index of ~1.7 for LaF3 and ~1.4 for MgF2, together with extinction coefficients of ~2×10-4 on 193nm were realized. The transmission of AR coating for 193nm achieved by using optimized deposition techniques is 99.8%. Second, a method of designing shadowing masks was developed to solve the problem of correcting coating thickness distributions for complex DUV systems. By using the method, the thickness distribution error specification of 3% PV has been achieved on substrates with ~300mm diameters and large curvatures. Finally, the laser calorimetry method is used to evaluate the laser radiation stability of fluoride coatings. It is turned out that the damage coefficients of fluoride coatings, which are defined as the values of unrecoverable increase of the absorption during the laser irradiation process, are much lower than that of fused silica substrates. The above progresses could further support the realization of high performance DUV optical systems.

  3. Molecular origins of nonlinear optical activity in zinc tris(thiourea)sulfate revealed by high-resolution x-ray diffraction data and ab initio calculations

    Science.gov (United States)

    Cole, Jacqueline M.; Hickstein, Daniel D.

    2013-11-01

    Structure-property relationships are established in the nonlinear optical (NLO) material, zinc tris(thiourea)sulfate (ZTS), via an experimental charge-density study, x-ray constrained wave-function refinement, and quantum-mechanical calculations. The molecular charge-transfer characteristics of ZTS, that are important for NLO activity, are topologically analyzed via a multipolar refinement of high-resolution x-ray diffraction data, which is supported by neutron diffraction measurements. The extent to which each chemical bond is ionic or covalent in nature is categorized by Laplacian-based bonding classifiers of the electron density; these include bond ellipticities, energy densities, and the local source function. Correspondingly, the NLO origins of ZTS are judged to best resemble those of organic NLO materials. The molecular dipole moment, μi, and (hyper)polarizability coefficients, αij and βijk, are calculated from the experimental diffraction data using the x-ray constrained wave-function method. Complementary gas-phase ab initio quantum-mechanical calculations of μi, αij, and βijk offer a supporting comparison. When taken alone, the experimental charge-density analysis does not fare well in deriving μi, αij, or βijk, which is not entirely surprising given that the associated calculations are only generally valid for organic molecules. However, by refining the x-ray data within the constrained wave-function method, the evaluations of μi, αij, and βijk are shown to agree very well with those from ab initio calculations and show remarkable normalization to experimental refractive index measurements. The small differences observed between ab initio and x-ray constrained wave-function refinement results can be related directly to gas- versus solid-state phase differences. μi is found to be 28.3 Debye (gas phase) and 29.7 Debye (solid state) while βijk coefficients are not only significant but are also markedly three dimensional in form. Accordingly

  4. High capacity optical links for datacentre connectivity

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Usuga, Mario; Vegas Olmos, Juan José

    There is a timely and growing demand for high capacity optical data transport solutions to provide connectivity inside data centres and between data centres located at different geographical locations. The requirements for reach are in the order of 2 km for intra-datacentre and up to 100 km for i...

  5. Optical fiber sensor having an active core

    Science.gov (United States)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1993-01-01

    An optical fiber is provided. The fiber is comprised of an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable a is the radius of the active fiber core and k is defined as 2 pi/lambda wherein lambda is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

  6. High sensitivity optically pumped quantum magnetometer.

    Science.gov (United States)

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  7. Optical high-performance computing: introduction to the JOSA A and Applied Optics feature.

    Science.gov (United States)

    Caulfield, H John; Dolev, Shlomi; Green, William M J

    2009-08-01

    The feature issues in both Applied Optics and the Journal of the Optical Society of America A focus on topics of immediate relevance to the community working in the area of optical high-performance computing.

  8. Fiber Optic Component Tests In High Speed Data Bus Applications

    Science.gov (United States)

    Creswell, R.; Drake, M. D.; Husbands, C. R.

    1982-12-01

    A series of tests was performed to evaluate off-the-shelf components for the design of a fiber optic channel for the Nascom System Improvements Project in support of the NASA Goddard Space Flight Center. This paper describes the results of this series of tests, establishing operational performance of active and passive fiber optic components at data rates up to 150 Mb/s. These tests determine the transmission characteristics of the fiber optic transmitters and receivers and the effects of data rate, bit pattern sensitivity, and vestigial optical energy on the performance of these devices. Tests were also performed to evaluate the capability of fused biconical couplers to Function properly at these high data rates.

  9. High Stability Optical Mount for Space Laser Applications

    Science.gov (United States)

    Mosciarello, P.; Di Carmine, E.

    2014-06-01

    In the frame of Atmospheric Lidar (ATLID) project, one of the active instruments foreseen to be boarded on the EarthCARE satellite, a high stability optical mount has been designed, developed and tested in order to fulfil the tight program requirements.A description of the design solution developed, manufactured and qualified for the most critical optical mount inside the PLH, located on the Laser Master Oscillator Plate (the laser resonance cavity), is presented. In order to minimize optical mount mass and envelope, the developed solution foresees a glued interface (I/F) between the mechanical support and the mirror.A collection of stability results obtained on the optical mount breadboards is also presented, including a description of environmental tests performed and the way to assess the mirror stability after each environmental test, as well as the acceptance criteria derived in order to establish the flight worthiness of the manufactured and assembled hardware.

  10. Highly Sensitive Electro-Optic Modulators

    Energy Technology Data Exchange (ETDEWEB)

    DeVore, Peter S [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2015-10-26

    There are very important diagnostic and communication applications that receive faint electrical signals to be transmitted over long distances for capture. Optical links reduce bandwidth and distance restrictions of metal transmission lines; however, such signals are only weakly imprinted onto the optical carrier, resulting in low fidelity transmission. Increasing signal fidelity often necessitates insertion of radio-frequency (RF) amplifiers before the electro-optic modulator, but (especially at high frequencies) RF amplification results in large irreversible distortions. We have investigated the feasibility of a Sensitive and Linear Modulation by Optical Nonlinearity (SALMON) modulator to supersede RF-amplified modulators. SALMON uses cross-phase modulation, a manifestation of the Kerr effect, to enhance the modulation depth of an RF-modulated optical wave. This ultrafast process has the potential to result in less irreversible distortions as compared to a RF-amplified modulator due to the broadband nature of the Kerr effect. Here, we prove that a SALMON modulator is a feasible alternative to an RFamplified modulator, by demonstrating a sensitivity enhancement factor greater than 20 and significantly reduced distortion.

  11. Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

    Science.gov (United States)

    Fazal, Muhammad Irfan

    The unabated demand for more capacity due to the ever-increasing internet traffic dictates that the boundaries of the state of the art maybe pushed to send more data through the network. Traditionally, this need has been satisfied by multiple wavelengths (wavelength division multiplexing), higher order modulation formats and coherent communication (either individually or combined together). WDM has the ability to reduce cost by using multiple channels within the same physical fiber, and with EDFA amplifiers, the need for O-E-O regenerators is eliminated. Moreover the availability of multiple colors allows for wavelength-based routing and network planning. Higher order modulation formats increases the capacity of the link by their ability to encode data in both the phase and amplitude of light, thereby increasing the bits/sec/Hz as compared to simple on-off keyed format. Coherent communications has also emerged as a primary means of transmitting and receiving optical data due to its support of formats that utilize both phase and amplitude to further increase the spectral efficiency of the optical channel, including quadrature amplitude modulation (QAM) and quadrature phase shift keying (QPSK). Polarization multiplexing of channels can double capacity by allowing two channels to share the same wavelength by propagating on orthogonal polarization axis and is easily supported in coherent systems where the polarization tracking can be performed in the digital domain. Furthermore, the forthcoming IEEE 100 Gbit/s Ethernet Standard, 802.3ba, provides greater bandwidth, higher data rates, and supports a mixture of modulation formats. In particular, Pol-MUX QPSK is increasingly becoming the industry's format of choice as the high spectral efficiency allows for 100 Gbit/s transmission while still occupying the current 50 GHz/channel allocation of current 10 Gbit/s OOK fiber systems. In this manner, 100 Gbit/s transfer speeds using current fiber links, amplifiers, and filters

  12. Hybrid optical antenna with high directivity gain.

    Science.gov (United States)

    Bonakdar, Alireza; Mohseni, Hooman

    2013-08-01

    Coupling of a far-field optical mode to electronic states of a quantum absorber or emitter is a crucial process in many applications, including infrared sensors, single molecule spectroscopy, and quantum metrology. In particular, achieving high quantum efficiency for a system with a deep subwavelength quantum absorber/emitter has remained desirable. In this Letter, a hybrid optical antenna based on coupling of a photonic nanojet to a metallo-dielectric antenna is proposed, which allows such efficient coupling. A quantum efficiency of about 50% is predicted for a semiconductor with volume of ~λ³/170. Despite the weak optical absorption coefficient of 2000 cm(-1) in the long infrared wavelength of ~8 μm, very strong far-field coupling has been achieved, as evidenced by an axial directivity gain of 16 dB, which is only 3 dB below of theoretical limit. Unlike the common phased array antenna, this structure does not require coherent sources to achieve a high directivity. The quantum efficiency and directivity gain are more than an order of magnitude higher than existing metallic, dielectric, or metallo-dielectric optical antenna.

  13. Optical activity of chirally distorted nanocrystals

    Science.gov (United States)

    Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

    2016-05-01

    We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

  14. On the classical theory of molecular optical activity

    CERN Document Server

    Frolov, Alexei M

    2010-01-01

    The basic principles of classical and semi-classical theories of molecular optical activity are discussed. These theories are valid for dilute solutions of optically active organic molecules. It is shown that all phenomena known in the classical theory of molecular optical activity can be described with the use of one pseudo-scalar which is a uniform function of the incident light frequency $\\omega$. The relation between optical rotation and circular dichroism is derived from the basic Kramers-Kronig relations. In our discussion of the general theory of molecular optical activity we introduce the tensor of molecular optical activity. It is shown that to evaluate the optical rotation and circular dichroism at arbitrary frequencies one needs to know only nine (3 + 6) molecular tensors. The quantum (or semi-classical) theory of molecular optical activity is also briefly discussed. We also raise the possibility of measuring the optical rotation and circular dichroism at wavelengths which correspond to the vacuum ...

  15. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  16. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  17. High-speed analog fiber optic links for satellite communication

    Science.gov (United States)

    Daryoush, A. S.; Herczfeld, P. R.; Kunath, R. R.

    1988-01-01

    Large-aperture phased array antennas operating at millimeter wave frequencies are designed for space-based communications and imaging. Array elements are comprised of active transmit/receive (T/R) modules which are linked to the central processing unit through a high-speed fiberoptic network. This paper demonstrates optical control of active modules for satellite communication at 24 GHz. An approach called T/R level data mixing, which utilizes fiberoptic transmission of a data signal to individual T/R modules to be upconverted by an optically synchronized local oscillator, is demonstrated at 24 GHz. A free-running HEMT oscillator, used as local oscillator at 24 GHz, is synchronized using indirect subharmonic optical injection locking over a locking range of 14 MHz. Results of data link performance over 500-1000 MHz is also reported in terms of gain-bandwidth, linearity and third-order intercept, sensitivity, and dynamic range.

  18. Traceability of high focal length cameras with diffractive optical elements

    Science.gov (United States)

    Lages Martins, L.; Silva Ribeiro, A.; Sousa, J. Alves e.

    2016-11-01

    This paper describes the use of diffractive optical elements (DOEs) for metrological traceable geometrical testing of high focal length cameras applied in the observation of large- scale structures. DOEs and related mathematical models are briefly explained. Laboratorial activities and results are described for the case of a high focal length camera used for longdistance displacement measurement of a long-span (2278 m) suspension bridge.

  19. Towards green high capacity optical networks

    Science.gov (United States)

    Glesk, I.; Mohd Warip, M. N.; Idris, S. K.; Osadola, T. B.; Andonovic, I.

    2012-02-01

    The demand for fast, secure, energy efficient high capacity networks is growing. It is fuelled by transmission bandwidth needs which will support among other things the rapid penetration of multimedia applications empowering smart consumer electronics and E-businesses. All the above trigger unparallel needs for networking solutions which must offer not only high-speed low-cost "on demand" mobile connectivity but should be ecologically friendly and have low carbon footprint. The first answer to address the bandwidth needs was deployment of fibre optic technologies into transport networks. After this it became quickly obvious that the inferior electronic bandwidth (if compared to optical fiber) will further keep its upper hand on maximum implementable serial data rates. A new solution was found by introducing parallelism into data transport in the form of Wavelength Division Multiplexing (WDM) which has helped dramatically to improve aggregate throughput of optical networks. However with these advancements a new bottleneck has emerged at fibre endpoints where data routers must process the incoming and outgoing traffic. Here, even with the massive and power hungry electronic parallelism routers today (still relying upon bandwidth limiting electronics) do not offer needed processing speeds networks demands. In this paper we will discuss some novel unconventional approaches to address network scalability leading to energy savings via advance optical signal processing. We will also investigate energy savings based on advanced network management through nodes hibernation proposed for Optical IP networks. The hibernation reduces the network overall power consumption by forming virtual network reconfigurations through selective nodes groupings and by links segmentations and partitionings.

  20. Bidirectional all-optical switches based on highly nonlinear optical fibers

    Science.gov (United States)

    Liu, Wenjun; Yang, Chunyu; Liu, Mengli; Yu, Weitian; Zhang, Yujia; Lei, Ming; Wei, Zhiyi

    2017-05-01

    All-optical switches have become one of the research focuses of nonlinear optics due to their fast switching speed. They have been applied in such fields as ultrafast optics, all-optical communication and all-optical networks. In this paper, based on symbolic computation, bidirectional all-optical switches are presented using analytic two-soliton solutions. Various types of soliton interactions are analyzed through choosing the different parameters of high-order dispersion and nonlinearity. Results indicate that bidirectional all-optical switches can be effectively achieved using highly nonlinear optical fibers.

  1. LSST active optics system software architecture

    Science.gov (United States)

    Thomas, Sandrine J.; Chandrasekharan, Srinivasan; Lotz, Paul; Xin, Bo; Claver, Charles; Angeli, George; Sebag, Jacques; Dubois-Felsmann, Gregory P.

    2016-08-01

    The Large Synoptic Survey Telescope (LSST) is an 8-meter class wide-field telescope now under construction on Cerro Pachon, near La Serena, Chile. This ground-based telescope is designed to conduct a decade-long time domain survey of the optical sky. In order to achieve the LSST scientific goals, the telescope requires delivering seeing limited image quality over the 3.5 degree field-of-view. Like many telescopes, LSST will use an Active Optics System (AOS) to correct in near real-time the system aberrations primarily introduced by gravity and temperature gradients. The LSST AOS uses a combination of 4 curvature wavefront sensors (CWS) located on the outside of the LSST field-of-view. The information coming from the 4 CWS is combined to calculate the appropriate corrections to be sent to the 3 different mirrors composing LSST. The AOS software incorporates a wavefront sensor estimation pipeline (WEP) and an active optics control system (AOCS). The WEP estimates the wavefront residual error from the CWS images. The AOCS determines the correction to be sent to the different degrees of freedom every 30 seconds. In this paper, we describe the design and implementation of the AOS. More particularly, we will focus on the software architecture as well as the AOS interactions with the various subsystems within LSST.

  2. Feasibility of Extreme Ultraviolet Active Optical Clock

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Wei; CHEN Jing-Biao

    2011-01-01

    @@ We propose an experimental scheme of vacuum ultraviolet(VUV)and extreme ultraviolet(XUV)optical fre-quency standards with noble gas atoms.Considering metastable state 3P2 noble atoms pumped by a conventional discharging method,the atomic beam is collimated with transverse laser cooling at the metastable state and en-ters into the laser cavity in the proposed setup.Due to stimulated emission from the metasable state to the ground state inside the laser cavity consisting of VUV reflection coating mirrors,our calculations show that with enough population inversion to compensate for the cavity loss,an active optical frequency standard at VUV and XUV is feasible.

  3. Low-cost active optical system for fire surveillance

    Science.gov (United States)

    Utkin, A. B.; Lavrov, A. V.; Vilar, R. M.

    2009-06-01

    Detection of smoke plumes using active optical sensors provides many advantages with respect to passive methods of fire surveillance. However, the price of these sensors is often too high as compared to passive fire detection instruments, such as infrared and video cameras. This article describes robust and cost effective diode-laser optical sensor for automatic fire surveillance in industrial environment. Physical aspects of the sensing process allowing to simplify the hardware and software design, eventually leading to significant reduction of manufacturing and maintenance costs, are discussed.

  4. High-resolution CT of lesions of the optic nerve

    Energy Technology Data Exchange (ETDEWEB)

    Peyster, R.G.; Hoover, E.D.; Hershey, B.L.; Haskin, M.E.

    1983-05-01

    The optic nerves are well demonstrated by high-resolution computed tomography. Involvement of the optic nerve by optic gliomas and optic nerve sheath meningiomas is well known. However, nonneoplastic processes such as increased intracranial pressure, optic neuritis, Grave ophthalmopathy, and orbital pseudotumor may also alter the appearance of the optic nerve/sheath on computed tomography. Certain clinical and computed tomographic features permit distinction of these nonneoplastic tumefactions from tumors.

  5. HIGH-EFFICIENCY AUTONOMOUS LASER ADAPTIVE OPTICS

    Energy Technology Data Exchange (ETDEWEB)

    Baranec, Christoph [Institute for Astronomy, University of Hawai' i at Mānoa, Hilo, HI, NZ 96720-2700 (United States); Riddle, Reed; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Dekany, Richard; Kulkarni, Shrinivas [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Law, Nicholas M. [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-3255 (United States); Ramaprakash, A. N.; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Punnadi, Sujit, E-mail: baranec@hawaii.edu [Inter-University Centre for Astronomy and Astrophysics, Ganeshkhind, Pune 411007 (India)

    2014-07-20

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limit their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  6. Optics of high-performance electron microscopes.

    Science.gov (United States)

    Rose, H H

    2008-01-01

    During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by multipole fields and to a discussion of the most advanced design that take advantage of these techniques. The theory of electron mirrors is developed and it is shown how this can be used to correct aberrations and to design energy filters. Finally, different types of energy filters are described.

  7. High-sensitivity fiber optic acoustic sensors

    Science.gov (United States)

    Lu, Ping; Liu, Deming; Liao, Hao

    2016-11-01

    Due to the overwhelming advantages compared with traditional electronicsensors, fiber-optic acoustic sensors have arisen enormous interest in multiple disciplines. In this paper we present the recent research achievements of our group on fiber-optic acoustic sensors. The main point of our research is high sensitivity interferometric acoustic sensors, including Michelson, Sagnac, and Fabry-Pérot interferometers. In addition, some advanced technologies have been proposed for acoustic or acoustic pressure sensing such as single-mode/multimode fiber coupler, dual FBGs and multi-longitudinal mode fiber laser based acoustic sensors. Moreover, our attention we have also been paid on signal demodulation schemes. The intensity-based quadrature point (Q-point) demodulation, two-wavelength quadrature demodulation and symmetric 3×3 coupler methodare discussed and compared in this paper.

  8. High-efficiency Autonomous Laser Adaptive Optics

    CERN Document Server

    Baranec, Christoph; Law, Nicholas M; Ramaprakash, A N; Tendulkar, Shriharsh; Hogstrom, Kristina; Bui, Khanh; Burse, Mahesh; Chordia, Pravin; Das, Hillol; Dekany, Richard; Kulkarni, Shrinivas; Punnadi, Sujit

    2014-01-01

    As new large-scale astronomical surveys greatly increase the number of objects targeted and discoveries made, the requirement for efficient follow-up observations is crucial. Adaptive optics imaging, which compensates for the image-blurring effects of Earth's turbulent atmosphere, is essential for these surveys, but the scarcity, complexity and high demand of current systems limits their availability for following up large numbers of targets. To address this need, we have engineered and implemented Robo-AO, a fully autonomous laser adaptive optics and imaging system that routinely images over 200 objects per night with an acuity 10 times sharper at visible wavelengths than typically possible from the ground. By greatly improving the angular resolution, sensitivity, and efficiency of 1-3 m class telescopes, we have eliminated a major obstacle in the follow-up of the discoveries from current and future large astronomical surveys.

  9. Vibrational optical activity principles and applications

    CERN Document Server

    Nafie, Laurence A

    2011-01-01

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

  10. Fabrication and tolerances of optics for high concentration photovoltaics

    OpenAIRE

    Benitez Gimenez, Pablo; Miñano Dominguez, Juan Carlos; Ahmadpanaih, Hamed; Mendes Lopes, Joao; Zamora Herranz, Pablo

    2014-01-01

    High Concentration Photovoltaics (HCPV) require an optical system with high efficiency, low cost and large tolerance. We describe the particularities of the HCPV applications, which constrain the optics design and the manufacturing techonologies.

  11. A special issue on High.Speed Optical Transmission and Processing

    Institute of Scientific and Technical Information of China (English)

    Jian WANG

    2013-01-01

    The rapid growth in network capacity and traffic rates raises the significance of high-speed optical transmission and processing. Recent progress in optical communication systems in relation to multiplexing technologies in different degrees of freedom, advanced multi-level modulation formats, coherent detection and digital signal processing has facilitated dramatic increases in transmission capacity. To be compatible with high-speed optical transmission, high- speed optical processing has gained increased interest to enable fast data manipulation in the optical domain and avoid cumbersome optical-electrical-optical conversions at network nodes. Recent progress in nonlinear-optical devices has led to enhanced efficiency, flexibility and functionality of ultrafast nonlinear-optical signal processing. It is expected that these advances in high-speed optical transmission and processing will pave the way to achieve superior performance of high-speed optical networks. It is our intention to bring the research community's attention to these hot topics in optical communication systems and networks. In this "Special Issue on High-Speed Optical Transmission and Processing", 8 review articles and 2 research articles focusing on relevant subjects by internationally active groups in the field are specially presented.

  12. High data rate optical transceiver terminal

    Science.gov (United States)

    Clarke, E. S.

    1973-01-01

    The objectives of this study were: (1) to design a 400 Mbps optical transceiver terminal to operate from a high-altitude balloon-borne platform in order to permit the quantitative evaluation of a space-qualifiable optical communications system design, (2) to design an atmospheric propagation experiment to operate in conjunction with the terminal to measure the degrading effects of the atmosphere on the links, and (3) to design typical optical communications experiments for space-borne laboratories in the 1980-1990 time frame. As a result of the study, a transceiver package has been configured for demonstration flights during late 1974. The transceiver contains a 400 Mbps transmitter, a 400 Mbps receiver, and acquisition and tracking receivers. The transmitter is a Nd:YAG, 200 Mhz, mode-locked, CW, diode-pumped laser operating at 1.06 um requiring 50 mW for 6 db margin. It will be designed to implement Pulse Quaternary Modulation (PQM). The 400 Mbps receiver utilizes a Dynamic Crossed-Field Photomultiplier (DCFP) detector. The acquisition receiver is a Quadrant Photomultiplier Tube (QPMT) and receives a 400 Mbps signal chopped at 0.1 Mhz.

  13. The Parameters Selection of SMA Optically Activated an Its Application

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhi-min; CHEN Yu-ming; YU Xiao-lei

    2002-01-01

    Shape Memory Alloy ( SMA ) optically activated is the key technology of optical SMA activator.According to the shape memory mechanism of SMA, researches are done on the activating response time and light wavelength of activating source etc of SMA optically activated to approach the parameters selection of optical activation. SMA has the optimum efficiency in the range of 13 seconds to 27 seconds when SMA is illuminated continuously by wavelength of 675um; The power of light wave has a low effect on SMA; The longer the activating wavelength, the quicker the response time of SMA activated. If the proper activating time and activating wavelength are adopted, and the structure deformation of composite material of SMA imbedded may be actively controlled, an ideal effect will be gotten. The research provides an evidence for the design of optical SMA activator and is of great significance to its application. The research on smart structure has a wide application prospect.

  14. Current Trends of High capacity Optical Interconnection Data Link in High Performance Optical Communication Systems

    Directory of Open Access Journals (Sweden)

    Ahmed Nabih Zaki Rashed

    2013-02-01

    Full Text Available Optical technologies are ubiquitous in telecommunications networks and systems, providing multiple wavelength channels of transport at 2.5 Gbit/sec to 40 Gbit/sec data rates over single fiber optic cables. Market pressures continue to drive the number of wavelength channels per fiber and the data rate per channel. This trend will continue for many years to come as electronic commerce grows and enterprises demand higher and reliable bandwidth over long distances. Electronic commerce, in turn, is driving the growth curves for single processor and multiprocessor performance in data base transaction and Web based servers. Ironically, the insatiable taste for enterprise network bandwidth, which has driven up the volume and pushed down the price of optical components for telecommunications, is simultaneously stressing computer system bandwidth increasing the need for new interconnection schemes and providing for the first time commercial opportunities for optical components in computer systems. The evolution of integrated circuit technology is causing system designs to move towards communication based architectures. We have presented the current tends of high performance system capacity of optical interconnection data transmission link in high performance optical communication and computing systems over wide range of the affecting parameters.

  15. Broadband angle- and permittivity-insensitive nondispersive optical activity based on chiral metamaterials

    CERN Document Server

    Song, Kun; Su, Zhaoxian; Ding, Changlin; Liu, Yahong; Luo, Chunrong; Zhao, Xiaopeng; Bhattarai, Khagendra; Zhou, Jiangfeng

    2016-01-01

    Because of the strong inherent resonances, the giant optical activity obtained via chiral metamaterials generally suffers from high dispersion, which has been a big stumbling block to broadband applications. In this paper, we propose a type of chiral metamaterial consisting of interconnected metal helix structures with four-fold symmetry, which exhibits nonresonant Drude-like response and can therefore avoid the highly dispersive optical activity resulting from resonances. It shows that the well-designed chiral metamaterial can achieve nondispersive and pure optical activity with high transmittance in a broadband frequency range. And the optical activity of multi-layer chiral metamaterials is proportional to the layer numbers of single-layer chiral metamaterial. Most remarkably, the broadband behaviors of nondispersive optical activity and high transmission are insensitive to the incident angles of electromagnetic waves and permittivity of dielectric substrate, thereby enabling more flexibility in polarizatio...

  16. Symbolic modeling of high energy beam optics

    CERN Document Server

    Autin, Bruno

    1999-01-01

    A classical problem of computational physics consists of finding the minimum of a chi /sup 2/ like function of many variables. Powerful optimization algorithms have been developed but do not guarantee convergence towards an absolute minimum. Analytical methods can improve the insight into a physical problem but calculations quickly exceed the power of a human brain. There comes the interest of optical design of high energy particle accelerators. The physics background is sketched and emphasis is put on the methodology. In practice, algebraic models may not be precise enough but they usually provide excellent initial conditions for a final numerical optimization. (4 refs).

  17. Detecting eavesdropping activity in fiber optic networks

    Science.gov (United States)

    MacDonald, Gregory G.

    The secure transmission of data is critical to governments, military organizations, financial institutions, health care providers and other enterprises. The primary method of securing in-transit data is though data encryption. A number of encryption methods exist but the fundamental approach is to assume an eavesdropper has access to the encrypted message but does not have the computing capability to decrypt the message in a timely fashion. Essentially, the strength of security depends on the complexity of the encryption method and the resources available to the eavesdropper. The development of future technologies, most notably quantum computers and quantum computing, is often cited as a direct threat to traditional encryption schemes. It seems reasonable that additional effort should be placed on prohibiting the eavesdropper from coming into possession of the encrypted message in the first place. One strategy for denying possession of the encrypted message is to secure the physical layer of the communications path. Because the majority of transmitted information is over fiber-optic networks, it seems appropriate to consider ways of enhancing the integrity and security of the fiber-based physical layer. The purpose of this research is to investigate the properties of light, as they are manifested in single mode fiber, as a means of insuring the integrity and security of the physical layer of a fiber-optic based communication link. Specifically, the approach focuses on the behavior of polarization in single mode fiber, as it is shown to be especially sensitive to fiber geometry. Fiber geometry is necessarily modified during the placement of optical taps. The problem of detecting activity associated with the placement of an optical tap is herein approached as a supervised machine learning anomaly identification task. The inputs include raw polarization measurements along with additional features derived from various visualizations of the raw data (the inputs are

  18. WIYN active optics: a platform for AO

    Science.gov (United States)

    Code, Arthur D.; Claver, Charles F.; Goble, Larry W.; Jacoby, George H.; Sawyer, David G.

    1998-09-01

    The WIYN 3.5 meter telescope is situated on the southwest ridge of Kitt Peak yielding excellent atmosphere seeing conditions. As such, the telescope and enclosure design was directed towards exploiting this feature. The primary mirror was spun cast and figured by the Steward Observatory Mirror Laboratory and the secondary mirror by Contraves. In both cases the performance exceeded the design specifications. The borosilicate primary is actively temperature controlled to within 0.2 C of the desired temperature, typically 0.5 degrees C below the ambient air. The telescope structure is also temperature controlled and the enclosure is opened to the outside ion all sides, which all heat sources are vented to ducts carrying air downwind of the facility. The primary mirror is actively controlled for low order aberrations by 66 axial actuators which are adjusted open loop via force matrix look-up tables and closed loop via real-time wavefront curvature sensing measurements. The active optics also included real-time collimation and focus control. The telescope drive and guider are capable of providing tracking to a few hundredths of a second of arc. By employing active telescope control at this level, it is possible to maintain telescope and local wavefront distortion to a level where atmospheric effects dominate the image quality. Since a significant fraction of the power in the atmospheric disturbances is contained in image motion the first step in adaptive optics control will be simple tip tilt. Studies of higher order AO system are being carried out, as well as additional test characterizing the telescope and site. It is intended to continue such studies in an attempt to establish long term variances.

  19. Optical alignment of high resolution Fourier transform spectrometers

    Science.gov (United States)

    Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

    1980-01-01

    Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

  20. Highly stable piezoelectrically tunable optical cavities

    CERN Document Server

    Möhle, Katharina; Döringshoff, Klaus; Nagel, Moritz; Peters, Achim

    2013-01-01

    We have implemented highly stable and tunable frequency references using optical high finesse cavities which incorporate a piezo actuator. As piezo material we used ceramic PZT, crystalline quartz, or PZN-PT single crystals. Lasers locked to these cavities show a relative frequency stability better than 1 x 10^{-14}, which is most likely not limited by the piezo actuators. The piezo cavities can be electrically tuned over more than one free spectral range (> 1.5 GHz) with only a minor decrease in frequency stability. Furthermore, we present a novel cavity design, where the piezo actuator is prestressed between the cavity spacer components. This design features a hermetically sealable intra cavity volume suitable for, e.g., cavity enhanced spectroscopy.

  1. Active optics in Large Synoptic Survey Telescope

    Science.gov (United States)

    Liang, Ming; Krabbendam, Victor; Claver, Charles F.; Chandrasekharan, Srinivasan; Xin, Bo

    2012-09-01

    The Large Synoptic Survey Telescope (LSST) has a 3.5º field of view and F/1.2 focus that makes the performance quite sensitive to the perturbations of misalignments and mirror surface deformations. In order to maintain the image quality, LSST has an active optics system (AOS) to measure and correct those perturbations in a closed loop. The perturbed wavefront errors are measured by the wavefront sensors (WFS) located at the four corners of the focal plane. The perturbations are solved by the non-linear least square algorithm by minimizing the rms variation of the measured and baseline designed wavefront errors. Then the correction is realized by applying the inverse of the perturbations to the optical system. In this paper, we will describe the correction processing in the LSST AOS. We also will discuss the application of the algorithm, the properties of the sensitivity matrix and the stabilities of the correction. A simulation model, using ZEMAX as a ray tracing engine and MATLAB as an analysis platform, is set up to simulate the testing and correction loop of the LSST AOS. Several simulation examples and results are presented.

  2. Method for high-speed Manchester encoded optical signal generation

    DEFF Research Database (Denmark)

    Zhang, Jianfeng; Chi, Nan; Holm-Nielsen, Pablo Villanueva

    2004-01-01

    A method for high-speed Manchester encoded optical signal generation is proposed and demonstrated with a specially configured electro-optical modulator. A 10 Gb/s Manchester encoded optical signal was generated, and its bit-error-ratio (BER) performance was evaluated.......A method for high-speed Manchester encoded optical signal generation is proposed and demonstrated with a specially configured electro-optical modulator. A 10 Gb/s Manchester encoded optical signal was generated, and its bit-error-ratio (BER) performance was evaluated....

  3. Integration of active and passive polymer optics

    DEFF Research Database (Denmark)

    Christiansen, Mads Brøkner; Schøler, Mikkel; Kristensen, Anders

    2007-01-01

    protrusions and an integrated metal shadow mask. In the CNP process, a combined UV mask and nanoimprint stamp is embossed into the resist, which is softened by heating, and UV exposed. Hereby the mm to m m sized features are defined by the UV exposure through the metal mask, while nm-scale features are formed......We demonstrate a wafer scale fabrication process for integration of active and passive polymer optics: Polymer DFB lasers and waveguides. Polymer dye DFB lasers are fabricated by combined nanoimprint and photolithography (CNP). The CNP fabrication relies on an UV transparent stamp with nm sized...... by mechanical deformation (nanoimprinting). The lasers are integrated with undoped SU-8 polymer waveguides. The waferscale fabrication process has a yield above 90% and the emission wavelengths are reproduced within 2 nm. Confinement of the light on the chip is demonstrated, and the influence on the laser...

  4. High pressure fiber optic sensor system

    Science.gov (United States)

    Guida, Renato; Xia, Hua; Lee, Boon K; Dekate, Sachin N

    2013-11-26

    The present application provides a fiber optic sensor system. The fiber optic sensor system may include a small diameter bellows, a large diameter bellows, and a fiber optic pressure sensor attached to the small diameter bellows. Contraction of the large diameter bellows under an applied pressure may cause the small diameter bellows to expand such that the fiber optic pressure sensor may measure the applied pressure.

  5. High nonlinear optical anisotropy of urea nanofibers

    Science.gov (United States)

    Isakov, D.; de Matos Gomes, E.; Belsley, M.; Almeida, B.; Martins, A.; Neves, N.; Reis, R.

    2010-07-01

    Nanofibers consisting of the optically nonlinear organic molecule urea embedded in both poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) polymers were produced by the electrospinning technique. The second-harmonic generation produced by aligned fiber mats of these materials displays a strong dependence on the polarization of the incident light. In PVA-urea nanofibers the effectiveness in generating of the second-harmonic light is as high as that of a pure urea powder with an average grain size of 110 μm. The results suggest that single crystalline urea nanofibers were achieved with a long-range crystalline order extending into the range of 2-4 μm with PVA as the host polymer.

  6. Optical Assessment of Caries Lesion Structure and Activity

    Science.gov (United States)

    Lee, Robert Chulsung

    New, more sophisticated diagnostic tools are needed for the detection and characterization of caries lesions in the early stages of development. It is not sufficient to simply detect caries lesions, methods are needed to assess the activity of the lesion and determine if chemical or surgical intervention is needed. Previous studies have demonstrated that polarization sensitive optical coherence tomography (PS-OCT) can be used to nondestructively image the subsurface lesion structure and measure the thickness of the highly mineralized surface zone. Other studies have demonstrated that the rate of dehydration can be correlated with the lesion activity and that the rate can be measured using optical methods. The main objective of this work was to test the hypothesis that optical methods can be used to assess lesion activity on tooth coronal and root surfaces. Simulated caries models were used to develop and validate an algorithm for detecting and measuring the highly mineralized surface layer using PS-OCT. This work confirmed that the algorithm was capable of estimating the thickness of the highly mineralized surface layer with high accuracy. Near-infrared (NIR) reflectance and thermal imaging methods were used to assess activity of caries lesions by measuring the state of lesion hydration. NIR reflectance imaging performed the best for artificial enamel and natural coronal caries lesion samples, particularly at wavelengths coincident with the water absorption band at 1460-nm. However, thermal imaging performed the best for artificial dentin and natural root caries lesion samples. These novel optical methods outperformed the conventional methods (ICDAS II) in accurately assessing lesion activity of natural coronal and root caries lesions. Infrared-based imaging methods have shown potential for in-vivo applications to objectively assess caries lesion activity in a single examination. It is likely that if future clinical trials are a success, this novel imaging

  7. All-Optical Temporal Differentiator Using a High Resolution Optical Arbitrary Waveform Shaper

    Institute of Scientific and Technical Information of China (English)

    DONG Jian-Ji; LUO Bo-Wen; ZHANG Yin; LEI Lei; HUANG De-Xiu; ZHANG Xin-Liang

    2012-01-01

    We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper, which is based on liquid crystal on silicon switching elements, and both amplitude and phase of the spectrum are programmable. By designing specific transfer functions with the optical waveform shaper, we obtain first-, second-, and third-order differentiators for periodic pulses with small average errors. We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.%We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper,which is based on liquid crystal on silicon switching elements,and both amplitude and phase of the spectrum are programmable.By designing specific transfer functions with the optical waveform shaper,we obtain first-,second-,and third-order differentiators for periodic pulses with small average errors.We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.

  8. High-performance quantitative robust switching control for optical telescopes

    Science.gov (United States)

    Lounsbury, William P.; Garcia-Sanz, Mario

    2014-07-01

    This paper introduces an innovative robust and nonlinear control design methodology for high-performance servosystems in optical telescopes. The dynamics of optical telescopes typically vary according to azimuth and altitude angles, temperature, friction, speed and acceleration, leading to nonlinearities and plant parameter uncertainty. The methodology proposed in this paper combines robust Quantitative Feedback Theory (QFT) techniques with nonlinear switching strategies that achieve simultaneously the best characteristics of a set of very active (fast) robust QFT controllers and very stable (slow) robust QFT controllers. A general dynamic model and a variety of specifications from several different commercially available amateur Newtonian telescopes are used for the controller design as well as the simulation and validation. It is also proven that the nonlinear/switching controller is stable for any switching strategy and switching velocity, according to described frequency conditions based on common quadratic Lyapunov functions (CQLF) and the circle criterion.

  9. Rapid Polarization Activity in Optical Communication Systems

    Science.gov (United States)

    Yevick, David; Reimer, Michael; Soliman, George

    2010-03-01

    We have recently analyzed the high-speed polarization and polarization-mode-dispersion (PMD) transients associated with mechanical impacts on a dispersion compensation module consisting of several km of optical fiber. These generate in our experiments rotational frequencies of up to several hundred radians/sec on the Poincare sphere that can severely degrade the performance of both standard and non-conventional communications systems. Accordingly, we implemented several procedures for performing high-speed polarization measurements, employed these to analyze small and large amplitude excitations and compared the results with a heuristic fiber model. Theoretically, we extended our previous work on applying the Magnus expansion to the analysis of the dependence of the PMD and polarization-dependent-loss (PDL) on frequency. From these, we obtained simple procedures for modeling polarization behavior over a wide frequency range from a small number of experimental measurements. Finally, we analyzed the applicability of various models of stochastic time-dependent refractive index variations to system outage prediction.

  10. Optical Switching for Dynamic Distribution of Wireless-Over-Fiber Signals in Active Optical Networks

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Rodes, Guillermo; Tafur Monroy, Idelfonso

    2012-01-01

    of a four wavelength-division-multiplexed channel system operating on a WiMax frequency band and employing an orthogonal-frequency-division-multiplexing modulation at 625 Mbits/s per channel, transmission of the data over 20 km of optical fiber, and active switching in a 1 × 16 active optical switch...

  11. The design of space optical communications terminal with high efficient

    Science.gov (United States)

    Deng, Xiaoguo; Li, Gang; Jiang, Bo; Yang, Xiaoxu; Yan, Peipei

    2015-02-01

    In order to improve high-speed laser space optical communications terminal receive energy and emission energy, meet the demand of mini-type and light-type for space-based bear platform, based on multiple-reflect coaxial optical receiving antenna structure, while considering the installation difficulty, a high-efficient optical system had been designed, which aperture is off-axial, both signal-receiving sub-optical system and emission sub-optical system share a same primary optical path. By the separating light lens behind the primary optical path, the received light with little energy will be filtered and shaped and then transmitted to each detector, at the same time, by the coupling element, the high-power laser will be coupling into optical antenna, and then emitted to outside. Applied the power-detected optical system evaluate principle, the optimized off-axial optical system's efficiency had been compared with the coaxial optical system. While, analyzed the Gauss beam energy distribution by numerical theory, discussed that whether off-axis optical system can be an emission terminal, verify the feasibility of the theory of the design of the system.

  12. A note on optical activity and extrinsic chirality

    CERN Document Server

    Arteaga, Oriol

    2015-01-01

    It has been assumed that optical activity can be measured by illuminating alternatively a material with left- and right- handed circular polarized light and analyzing the differential response. This simple and intuitive approach is in general incorrect, and has led to misleading idea that extrinsic chirality involves optical activity.

  13. Active Learning Environment with Lenses in Geometric Optics

    Science.gov (United States)

    Tural, Güner

    2015-01-01

    Geometric optics is one of the difficult topics for students within physics discipline. Students learn better via student-centered active learning environments than the teacher-centered learning environments. So this study aimed to present a guide for middle school teachers to teach lenses in geometric optics via active learning environment…

  14. Active Learning Environment with Lenses in Geometric Optics

    Science.gov (United States)

    Tural, Güner

    2015-01-01

    Geometric optics is one of the difficult topics for students within physics discipline. Students learn better via student-centered active learning environments than the teacher-centered learning environments. So this study aimed to present a guide for middle school teachers to teach lenses in geometric optics via active learning environment…

  15. The catalystic asymmetric synthesis of optically active epoxy ketones

    NARCIS (Netherlands)

    Marsman, Bertha Gerda

    1981-01-01

    In this thesis the use of catalytic asymmetric synthesis to prepare optically active epoxy ketones is described. This means that the auxiliary chirality, necessary to obtain an optically active product, is added in a catalytic quantity . In principle this is a very efficient way to make opticlly

  16. Optical Transmitter Terminal for Selective RF High Frequency Bans Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the proposal work is to investigate the highly innovative conceptual design of an optical communication selective frequency transmitter terminal...

  17. TOCUSO: Test of Conceptual Understanding on High School Optics Topics

    Science.gov (United States)

    Akarsu, Bayram

    2012-01-01

    Physics educators around the world often need reliable diagnostic materials to measure students' understanding of physics concept in high school. The purpose of this study is to evaluate a new diagnostic tool on High School Optics concept. Test of Conceptual Understanding on High School Optics (TOCUSO) consists of 25 conceptual items that…

  18. High-speed digital fiber optic links for satellite traffic

    Science.gov (United States)

    Daryoush, A. S.; Ackerman, E.; Saedi, R.; Kunath, R. R.; Shalkhauser, K.

    1989-09-01

    Large aperture phased array antennas operating at millimeter wave frequencies are designed for space-based communications and imaging platforms. Array elements are comprised of active T/R modules which are linked to the central processing unit through high-speed fiber-optic networks. The system architecture satisfying system requirements at millimeter wave frequency is T/R level data mixing where data and frequency reference signals are distributed independently before mixing at the T/R modules. This paper demonstrates design procedures of a low loss high-speed fiber-optic link used for transmission of data signals over 600-900 MHz bandwidth inside satellite. The fiber-optic link is characterized for transmission of analog and digital data. A dynamic range of 79 dB/MHz was measured for analog data over the bandwidth. On the other hand, for bursted SMSK satellite traffic at 220 Mbps rates, BER of 2 x 10 to the -7th was measured for E(b)/N(o) of 14.3 dB.

  19. High Speed Fibre Optic Backbone LAN

    Science.gov (United States)

    Tanimoto, Masaaki; Hara, Shingo; Kajita, Yuji; Kashu, Fumitoshi; Ikeuchi, Masaru; Hagihara, Satoshi; Tsuzuki, Shinji

    1987-09-01

    Our firm has developed the SUMINET-4100 series, a fibre optic local area network (LAN), to serve the communications system trunk line needs for facilities, such as steel refineries, automobile plants and university campuses, that require large transmission capacity, and for the backbone networks used in intelligent building systems. The SUMINET-4100 series is already in service in various fields of application. Of the networks available in this series, the SUMINET-4150 has a trunk line speed of 128 Mbps and the multiplexer used for time division multiplexing (TDM) was enabled by designing an ECL-TTL gate array (3000 gates) based custom LSI. The synchronous, full-duplex V.24 and V.3.5 interfaces (SUMINET-2100) are provided for use with general purpose lines. And the IBM token ring network, the SUMINET-3200, designed for heterogeneous PCs and the Ethernet can all be connected to sub loops. Further, the IBM 3270 TCA and 5080 CADAM can be connected in the local mode. Interfaces are also provided for the NTT high-speed digital service, the digital PBX systems, and the Video CODEC system. The built-in loop monitor (LM) and network supervisory processor (NSP) provide management of loop utilization and send loop status signals to the host CPU's network configuration and control facility (NCCF). These built-in functions allow both the computer system and LAN to be managed from a single source at the host. This paper outlines features of the SUMINET-4150 and provides an example of its installation.

  20. Application of portable optical laboratory in high schools and colleges

    Science.gov (United States)

    Altshuler, Gregory B.; Belashenkov, Nickolai R.; Ermolaev, Vladimir S.; Inochkin, Mickle V.; Karasev, Vyatcheslav B.

    1995-10-01

    The present paper describes the experience of application of portable optical laboratory in optical practicum developed directly for training and demonstrations of basic optical laws and phenomena in high-schools, colleges and nontechnical universities all over Russia. The laboratory includes the portable optical platform with built-in laser and lamp sources, kit of optical components and software. These accessories provide the attractive and smart teaching in general optics during lectures, lessons and practice at schools and colleges. The portable optical laboratory provides 28 basic lab works and demonstrations in reflection, refraction, absorption and dispersion of light, interference, diffraction, polarization of light, image formation and waveguide propagation of light in optical fibers. Due to their interdependence one can teach and learn a whole course of general optics. The individual work of students and school children with optical kit stimulates and develops their creative abilities and experimental skills, as well increases the effectiveness of education. The kit is provided with optional elements for a number of extra experiments with holography, polarizing light propagation, simple optical devices etc. These extensions allow to modify the education process according to teacher's point of view. The conception of optical class-room based on portable optical laboratories is discussed. The effectiveness of individual and small-group training is analyzed.

  1. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators ...

  2. A new generation active arrays for optical flexibility in astronomical instrumentation

    Science.gov (United States)

    Kroes, G.; Jaskó, A.; Pragt, J. H.; Venema, L.; De Haan, M.

    2012-09-01

    Throughout the history of telescopes and astronomical instrumentation, new ways were found to open up unexplored possibilities in fundamental astronomical research by increasing the telescope size and instrumentation complexity. The ever demanding requirements on instrument performance pushes instrument complexity to the edge. In order to take the next leap forward in instrument development the optical design freedom needs to be increased drastically. The use of more complex and more accurate optics allows for shorter optical trains with smaller sizes, smaller number of components and reduced fabrication and alignment verification time and costs. Current optics fabrication is limited in surface form complexity and/or accuracy. Traditional active and adaptive optics lack the needed intrinsic long term stability and simplicity in design, manufacturing, verification and control. This paper explains how and why active arrays literally provide a flexible but stable basis for the next generation optical instruments. Combing active arrays with optically high quality face sheets more complex and accurate optical surface forms can be provided including extreme a-spherical (freeform) surfaces and thus allow for optical train optimization and even instrument reconfiguration. A zero based design strategy is adopted for the development of the active arrays addressing fundamental issues in opto-mechanical engineering. The various choices are investigated by prototypes and Finite Element Analysis. Finally an engineering concept will be presented following a highly stable adjustment strategy allowing simple verification and control. The Optimization metrology is described in an additional paper for this conference by T. Agócs et al.

  3. High-speed optical correlation-domain reflectometry without using acousto-optic modulator

    CERN Document Server

    Shizuka, Makoto; Hayashi, Neisei; Mizuno, Yosuke; Nakamura, Kentaro

    2015-01-01

    To achieve a distributed reflectivity measurement along an optical fiber, we develop a simplified cost-effective configuration of optical correlation- (or coherence-) domain reflectometry based on a synthesized optical coherence function by sinusoidal modulation. By excluding conventional optical heterodyne detection (practically, without using an acousto-optic modulator) and by exploiting the foot of the Fresnel reflection spectrum, the electrical bandwidth required for signal processing is lowered down to several megahertz. We evaluate the basic system performance and demonstrate its high-speed operation (10 ms for one scan) by tracking a moving reflection point in real time.

  4. Configurational Molecular Glue: One Optically Active Polymer Attracts Two Oppositely Configured Optically Active Polymers.

    Science.gov (United States)

    Tsuji, Hideto; Noda, Soma; Kimura, Takayuki; Sobue, Tadashi; Arakawa, Yuki

    2017-03-24

    D-configured poly(D-lactic acid) (D-PLA) and poly(D-2-hydroxy-3-methylbutanoic acid) (D-P2H3MB) crystallized separately into their homo-crystallites when crystallized by precipitation or solvent evaporation, whereas incorporation of L-configured poly(L-2-hydroxybutanoic acid) (L-P2HB) in D-configured D-PLA and D-P2H3MB induced co-crystallization or ternary stereocomplex formation between D-configured D-PLA and D-P2H3MB and L-configured L-P2HB. However, incorporation of D-configured poly(D-2-hydroxybutanoic acid) (D-P2HB) in D-configured D-PLA and D-P2H3MB did not cause co-crystallization between D-configured D-PLA and D-P2H3MB and D-configured D-P2HB but separate crystallization of each polymer occurred. These findings strongly suggest that an optically active polymer (L-configured or D-configured polymer) like unsubstituted or substituted optically active poly(lactic acid)s can act as "a configurational or helical molecular glue" for two oppositely configured optically active polymers (two D-configured polymers or two L-configured polymers) to allow their co-crystallization. The increased degree of freedom in polymer combination is expected to assist to pave the way for designing polymeric composites having a wide variety of physical properties, biodegradation rate and behavior in the case of biodegradable polymers.

  5. Miniaturized High Performance Optical Gyroscope Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a new approach for to the design and fabrication of miniaturized Interferometric Fiber Optical Gyroscope (FOG) that enables the production of smaller IRU...

  6. Amorphous silicon rich silicon nitride optical waveguides for high density integrated optics

    DEFF Research Database (Denmark)

    Philipp, Hugh T.; Andersen, Karin Nordström; Svendsen, Winnie Edith

    2004-01-01

    Amorphous silicon rich silicon nitride optical waveguides clad in silica are presented as a high-index contrast platform for high density integrated optics. Performance of different cross-sectional geometries have been measured and are presented with regards to bending loss and insertion loss...

  7. Amorphous silicon rich silicon nitride optical waveguides for high density integrated optics

    DEFF Research Database (Denmark)

    Philipp, Hugh T.; Andersen, Karin Nordström; Svendsen, Winnie Edith

    2004-01-01

    Amorphous silicon rich silicon nitride optical waveguides clad in silica are presented as a high-index contrast platform for high density integrated optics. Performance of different cross-sectional geometries have been measured and are presented with regards to bending loss and insertion loss....... A sample double ring add-drop filter is presented....

  8. Fast optical signal processing in high bit rate OTDM systems

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Jepsen, Kim Stokholm; Clausen, Anders;

    1998-01-01

    As all-optical signal processing is maturing, optical time division multiplexing (OTDM) has also gained interest for simple networking in high capacity backbone networks. As an example of a network scenario we show an OTDM bus interconnecting another OTDM bus, a single high capacity user...

  9. Fiber optic chemical sensors: The evolution of high- density fiber-optic DNA microarrays

    Science.gov (United States)

    Ferguson, Jane A.

    2001-06-01

    Sensors were developed for multianalyte monitoring, fermentation monitoring, lactate analysis, remote oxygen detection for use in bioremediation monitoring and in a fuel spill clean-up project, heavy metal analysis, and high density DNA microarrays. The major focus of this thesis involved creating and improving high-density DNA gene arrays. Fiber optic sensors are created using fluorescent indicators, polymeric supports, and optical fiber substrates. The fluorescent indicator is entrapped in a polymer layer and attached to the tip of the optical fiber. The tip of the fiber bearing the sensing layer (the distal end) is placed in the sample of interest while the other end of the fiber (the proximal end) is connected to an analysis system. Any length of fiber can be used without compromising the integrity or sensitivity of the system. A fiber optic oxygen sensor was designed incorporating an oxygen sensitive fluorescent dye and a gas permeable polymer attached to an optical fiber. The construction simplicity and ruggedness of the sensor enabled its deployment for in situ chemical oxidation and bioremediation studies. Optical fibers were also used as the substrate to detect biomolecules in solution. To monitor bioprocesses, the production of the analyte of interest must be coupled with a species that is optically measurable. For example, oxygen is consumed in many metabolic functions. The fiber optic oxygen sensor is equipped with an additional sensing layer. Upon contact with a specific biochemical in the sample, a reaction occurs in the additional sensing layer that either consumes or produces oxygen. This dual layer system was used to monitor the presence of lactate, an important metabolite for clinical and bioprocess analysis. In many biological and environmental systems, the generation of one species occurs coincidentally with the generation or consumption of another species. A multianalyte sensor was prepared that can monitor the simultaneous activity of pH, CO2

  10. (Bio)hybrid materials based on optically active particles

    Science.gov (United States)

    Reitzig, Manuela; Härtling, Thomas; Opitz, Jörg

    2014-03-01

    In this contribution we provide an overview of current investigations on optically active particles (nanodiamonds, upconversion phospors) for biohybrid and sensing applications. Due to their outstanding properties nanodiamonds gain attention in various application elds such as microelectronics, optical monitoring, medicine, and biotechnology. Beyond the typical diamond properties such as high thermal conductivity and extreme hardness, the carbon surface and its various functional groups enable diverse chemical and biological surface functionalization. At Fraunhofer IKTS-MD we develop a customization of material surfaces via integration of chemically modi ed nanodiamonds at variable surfaces, e.g bone implants and pipelines. For the rst purpose, nanodiamonds are covalently modi ed at their surface with amino or phosphate functionalities that are known to increase adhesion to bone or titanium alloys. The second type of surface is approached via mechanical implementation into coatings. Besides nanodiamonds, we also investigate the properties of upconversion phosphors. In our contribution we show how upconversion phosphors are used to verify sterilization processes via a change of optical properties due to sterilizing electron beam exposure.

  11. Nonlinear optical signal processing for high-speed, spectrally efficient fiber optic systems and networks

    Science.gov (United States)

    Zhang, Bo

    The past decade has witnessed astounding boom in telecommunication network traffic. With the emergence of multimedia over Internet, the high-capacity optical transport systems have started to shift focus from the core network towards the end users. This trend leads to diverse optical networks with transparency and reconfigurability requirement. As single channel data rate continues to increase and channel spacing continues to shrink for high capacity, high spectral efficiency, the workload on conventional electronic signal processing elements in the router nodes continues to build up. Performing signal processing functions in the optical domain can potentially alleviate the speed bottleneck if the unique optical properties are efficiently leveraged to assist electronic processing methodologies. Ultra-high bandwidth capability along with the promise for multi-channel and format-transparent operation make optical signal processing an attractive technology which is expected to have great impact on future optical networks. For optical signal processing applications in fiber-optic network and systems, a laudable goal would be to explore the unique nonlinear optical processes in novel photonic devices. This dissertation investigates novel optical signal processing techniques through simulations and experimental demonstrations, analyzes limitations of these nonlinear processing elements and proposes techniques to enhance the system performance or designs for functional photonic modules. Two key signal-processing building blocks for future optical networks, namely slow-light-based tunable optical delay lines and SOA-based high-speed wavelength converters, are presented in the first part of the dissertation. Phase preserving and spectrally efficient slow light are experimentally demonstrated using advanced modulation formats. Functional and novel photonic modules, such as multi-channel synchronizer and variable-bit-rate optical time division multiplexer are designed and

  12. An inexpensive high-temperature optical fiber thermometer

    Science.gov (United States)

    Moore, Travis J.; Jones, Matthew R.; Tree, Dale R.; Allred, David D.

    2017-01-01

    An optical fiber thermometer consists of an optical fiber whose tip is coated with a highly conductive, opaque material. When heated, this sensing tip becomes an isothermal cavity that emits like a blackbody. This emission is used to predict the sensing tip temperature. In this work, analytical and experimental research has been conducted to further advance the development of optical fiber thermometry. An inexpensive optical fiber thermometer is developed by applying a thin coating of a high-temperature cement onto the tip of a silica optical fiber. An FTIR spectrometer is used to detect the spectral radiance exiting the fiber. A rigorous mathematical model of the irradiation incident on the detection system is developed. The optical fiber thermometer is calibrated using a blackbody radiator and inverse methods are used to predict the sensing tip temperature when exposed to various heat sources.

  13. High-speed optical phase-shifting apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Zortman, William A.

    2016-11-08

    An optical phase shifter includes an optical waveguide, a plurality of partial phase shifting elements arranged sequentially, and control circuitry electrically coupled to the partial phase shifting elements. The control circuitry is adapted to provide an activating signal to each of the N partial phase shifting elements such that the signal is delayed by a clock cycle between adjacent partial phase shifting elements in the sequence. The transit time for a guided optical pulse train between the input edges of consecutive partial phase shifting elements in the sequence is arranged to be equal to a clock cycle, thereby enabling pipelined processing of the optical pulses.

  14. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    Science.gov (United States)

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  15. High energy laser optics manufacturing: a preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Baird, E.D.

    1980-07-01

    This report presents concepts and methods, major conclusions, and major recommendations concerning the fabrication of high energy laser optics (HELO) that are to be machined by the Large Optics Diamond Turning Machine (LODTM) at the Lawrence Livermore National Laboratory (LLNL). Detailed discussions of concepts and methods proposed for metrological operations, polishing of reflective surfaces, mounting of optical components, construction of mirror substrates, and applications of coatings are included.

  16. The high education of optical engineering in East China

    Science.gov (United States)

    Liu, Xu; Liu, Xiangdong; Wang, Xiaoping; Bai, Jian; Liu, Yuling

    2014-07-01

    The history and the development of the high education in the field of optical engineering in the area of East China will be presented in the paper. The overall situation of research and human resource training in optics and photonics will also be reviewed, it shows that China needs lots of talents and experts in this field to support the world optical industry in East China.

  17. High-speed optical frequency-domain imaging

    OpenAIRE

    Yun, S. H.; Tearney, G. J.; Boer; Iftimia, N. V.; Bouma, B. E.

    2003-01-01

    We demonstrate high-speed, high-sensitivity, high-resolution optical imaging based on optical frequency-domain interferometry using a rapidly-tuned wavelength-swept laser. We derive and show experimentally that frequency-domain ranging provides a superior signal-to-noise ratio compared with conventional time-domain ranging as used in optical coherence tomography. A high sensitivity of −110 dB was obtained with a 6 mW source at an axial resolution of 13.5 µm and an A-line rate of 15.7 kHz, rep...

  18. Proposal for loadable and erasable optical memory unit based on dual active microring optical integrators

    Science.gov (United States)

    Ding, Yunhong; Zhang, Xiaobei; Zhang, Xinliang; Huang, Dexiu

    2008-11-01

    A novel approach for loadable and erasable optical memory unit based on dual microring optical integrators is proposed and studied. The optical integrator, which can generate an optical step function for data storing, is synthesized using active media for loss compensation and a tunable phase shifter for data reading at any time. The input data into the memory is return-to-zero (RZ) signal, and the output data read from the memory is also RZ format with a narrower pulse width. An optical digital register based on the proposed optical memory unit is also investigated and simulated, which shows the potential for large scale data storage and serial-to-parallel data conversion. A great number of such memory units can be densely integrated on a photonic circuit for future large scale data storage and buffer.

  19. Coherent control of optical activity and optical anisotropy of thin metamaterials

    CERN Document Server

    Mousavi, Seyedmohammad A; Shi, Jinhui; Zheludev, Nikolay I

    2013-01-01

    The future fibre optic communications network will rely on photons as carriers of information, which may be stored in intensity, polarization or phase of light. However, processing of such optical information usually relies on electronics. Aiming to avoid the conversion between optical and electronic signals, modulation of light with light based on optical nonlinearity has become a major research field, but real integrated all-optical systems face thermal management and energy challenges. On the other hand, it has recently been demonstrated that the interaction of two coherent light beams on a thin, lossy, linear material can lead to large and ultrafast intensity modulation at arbitrarily low power resulting from coherent absorption. Here we demonstrate that birefringence and optical activity (linear and circular birefringence and dichroism) of functional materials can be coherently controlled by placing a thin material slab into a standing wave formed by the signal and control waves. Efficient control of the...

  20. Coherent phonon optics in a chip with an electrically controlled active device.

    Science.gov (United States)

    Poyser, Caroline L; Akimov, Andrey V; Campion, Richard P; Kent, Anthony J

    2015-02-05

    Phonon optics concerns operations with high-frequency acoustic waves in solid media in a similar way to how traditional optics operates with the light beams (i.e. photons). Phonon optics experiments with coherent terahertz and sub-terahertz phonons promise a revolution in various technical applications related to high-frequency acoustics, imaging, and heat transport. Previously, phonon optics used passive methods for manipulations with propagating phonon beams that did not enable their external control. Here we fabricate a phononic chip, which includes a generator of coherent monochromatic phonons with frequency 378 GHz, a sensitive coherent phonon detector, and an active layer: a doped semiconductor superlattice, with electrical contacts, inserted into the phonon propagation path. In the experiments, we demonstrate the modulation of the coherent phonon flux by an external electrical bias applied to the active layer. Phonon optics using external control broadens the spectrum of prospective applications of phononics on the nanometer scale.

  1. Lewis acid promoted highly diastereoselective Petasis Borono-Mannich reaction: efficient synthesis of optically active β,γ-unsaturated α-amino acids.

    Science.gov (United States)

    Li, Yi; Xu, Ming-Hua

    2012-04-20

    An efficient and straightforward method for the preparation of highly enantiomerically enriched β,γ-unsaturated α-amino acid derivatives by a Lewis acid promoted diastereoselective Petasis reaction of vinylboronic acid, N-tert-butanesulfinamide, and glyoxylic acid has been developed. The synthetic utilities of the approach were demonstrated by the rapid and convenient construction of challenging cyclopenta[c]proline derivatives. © 2012 American Chemical Society

  2. Active Learning Strategies for Introductory Light and Optics

    Science.gov (United States)

    Sokoloff, David R.

    2016-01-01

    There is considerable evidence that traditional approaches are ineffective in teaching physics concepts, including light and optics concepts. A major focus of the work of the Activity Based Physics Group has been on the development of active learning curricula like RealTime Physics (RTP) labs and Interactive Lecture Demonstrations (ILDs). Among the characteristics of these curricula are: (1) use of a learning cycle in which students are challenged to compare predictions—discussed with their peers in small groups—to observations of the physical world, (2) use of guided hands-on work to construct basic concepts from observations, and (3) use of computer-based tools. It has been possible to change the lecture and laboratory learning environments at a large number of universities, colleges, and high schools without changing the structure of the introductory course. For example, in the United States, nearly 200 physics departments have adopted RTP, and many others use pre-publication, open-source versions or have adopted the RTP approach to develop their own labs. Examples from RTP and ILDs (including optics magic tricks) are described in this paper.

  3. DISSYMMETRY MODEL OF MOLECULAR POLARIZABILITY AND OPTICAL ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    周志华; 汤杰

    1991-01-01

    Dissymmetry model of molecular polarizability divided into some layers within a sphere,some rules and sequence according to the magnitude of polarizability replaced by bond refraction for many groups have been suggested.The relationship between the dissymmetry of molecular polarizability arrounding the dissymmetric carbon atom and the direction of optical activity has been discussed .The accuracy is above 95 persent to use our model and rules to determine over 6000 compounds of optical activity.

  4. Ultrafast chiroptical spectroscopy: Monitoring optical activity in quick time

    Directory of Open Access Journals (Sweden)

    Hanju Rhee

    2011-12-01

    Full Text Available Optical activity spectroscopy provides rich structural information of biologically important molecules in condensed phases. However, a few intrinsic problems of conventional method based on electric field intensity measurement scheme prohibited its extension to time domain technique. We have recently developed new types of optical activity spectroscopic methods capable of measuring chiroptical signals with femtosecond pulses. It is believed that these novel approaches will be applied to a variety of ultrafast chiroptical studies.

  5. High-accurate optical vector analysis based on optical single-sideband modulation

    Science.gov (United States)

    Xue, Min; Pan, Shilong

    2016-11-01

    Most of the efforts devoted to the area of optical communications were on the improvement of the optical spectral efficiency. Varies innovative optical devices are thus developed to finely manipulate the optical spectrum. Knowing the spectral responses of these devices, including the magnitude, phase and polarization responses, is of great importance for their fabrication and application. To achieve high-resolution characterization, optical vector analyzers (OVAs) based on optical single-sideband (OSSB) modulation have been proposed and developed. Benefiting from the mature and highresolution microwave technologies, the OSSB-based OVA can potentially achieve a resolution of sub-Hz. However, the accuracy is restricted by the measurement errors induced by the unwanted first-order sideband and the high-order sidebands in the OSSB signal, since electrical-to-optical conversion and optical-to-electrical conversion are essentially required to achieve high-resolution frequency sweeping and extract the magnitude and phase information in the electrical domain. Recently, great efforts have been devoted to improve the accuracy of the OSSB-based OVA. In this paper, the influence of the unwanted-sideband induced measurement errors and techniques for implementing high-accurate OSSB-based OVAs are discussed.

  6. Optical glass with tightest refractive index and dispersion tolerances for high-end optical designs

    Science.gov (United States)

    Jedamzik, R.; Reichel, S.; Hartmann, P.

    2014-03-01

    In high end optical designs the quality of the optical system not only depends on the chosen optical glasses but also on the available refractive index and Abbe number tolerances. The primary optical design is based on datasheet values of the refractive index and Abbe number. In general the optical position of the delivered glass will deviate from the catalog values by given tolerances due to production tolerances. Therefore in many cases the final optical design needs to be modified based on real glass data. Tighter refractive index and Abbe number tolerances can greatly reduce this additional amount of work. The refractive index and Abbe number of an optical glass is a function of the chemical composition and the annealing process. Tight refractive index tolerances require not only a close control and high reliability of the melting and fine annealing process but also best possible material data. These data rely on high accuracy measurement and accurate control during mass production. Modern melting and annealing procedure do not only enable tight index tolerances but also a high homogeneity of the optical properties. Recently SCHOTT was able to introduce the tightest available refractive index and Abbe number tolerance available in the market: step 0.5 meaning a refractive index tolerance of +/- 0.0001 and an Abbe number tolerance of +/- 0.1%. This presentation describes how the refractive index depends on the glass composition and annealing process and describes the requirements to get to this tightest refractive index and Abbe number tolerance.

  7. Using an Active-Optical Sensor to Develop an Optimal NDVI Dynamic Model for High-Yield Rice Production (Yangtze, China).

    Science.gov (United States)

    Liu, Xiaojun; Ferguson, Richard B; Zheng, Hengbiao; Cao, Qiang; Tian, Yongchao; Cao, Weixing; Zhu, Yan

    2017-03-24

    The successful development of an optimal canopy vegetation index dynamic model for obtaining higher yield can offer a technical approach for real-time and nondestructive diagnosis of rice (Oryza sativa L) growth and nitrogen (N) nutrition status. In this study, multiple rice cultivars and N treatments of experimental plots were carried out to obtain: normalized difference vegetation index (NDVI), leaf area index (LAI), above-ground dry matter (DM), and grain yield (GY) data. The quantitative relationships between NDVI and these growth indices (e.g., LAI, DM and GY) were analyzed, showing positive correlations. Using the normalized modeling method, an appropriate NDVI simulation model of rice was established based on the normalized NDVI (RNDVI) and relative accumulative growing degree days (RAGDD). The NDVI dynamic model for high-yield production in rice can be expressed by a double logistic model: RNDVI = ( 1 + e - 15.2829 × ( R A G D D i - 0.1944 ) ) - 1 - ( 1 + e - 11.6517 × ( R A G D D i - 1.0267 ) ) - 1 (R2 = 0.8577**), which can be used to accurately predict canopy NDVI dynamic changes during the entire growth period. Considering variation among rice cultivars, we constructed two relative NDVI (RNDVI) dynamic models for Japonica and Indica rice types, with R2 reaching 0.8764** and 0.8874**, respectively. Furthermore, independent experimental data were used to validate the RNDVI dynamic models. The results showed that during the entire growth period, the accuracy (k), precision (R2), and standard deviation of RNDVI dynamic models for the Japonica and Indica cultivars were 0.9991, 1.0170; 0.9084**, 0.8030**; and 0.0232, 0.0170, respectively. These results indicated that RNDVI dynamic models could accurately reflect crop growth and predict dynamic changes in high-yield crop populations, providing a rapid approach for monitoring rice growth status.

  8. Alternative high-resolution lithographic technologies for optical applications

    Science.gov (United States)

    Zeitner, Uwe D.; Weichelt, Tina; Bourgin, Yannick; Kinder, Robert

    2016-03-01

    Modern optical applications have special demands on the lithographic fabrication technologies. This relates to the lateral shape of the structures as well as to their three dimensional surface profile. On the other hand optical nano-structures are often periodic which allows for the use of dedicated lithographic exposure principles. The paper briefly reviews actual developments in the field of optical nano-structure generation. Special emphasis will be given to two technologies: electron-beam lithography based on a flexible cell-projection method and the actual developments in diffractive mask aligner lithography. Both offer a cost effective fabrication alternative for high resolution structures or three-dimensional optical surface profiles.

  9. Recent Advances in Ultra-High-Speed Optical Signal Processing

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao;

    2012-01-01

    We review recent advances in the optical signal processing of ultra-high-speed serial data signals up to 1.28 Tbit/s, with focus on applications of time-domain optical Fourier transformation. Experimental methods for the generation of symbol rates up to 1.28 Tbaud are also described....

  10. Activities to investigate wavelength-shifting optical fibers

    Science.gov (United States)

    Anderson, Megan; Strong, Denver; Baker, Blane

    2017-07-01

    Understanding principles and operation of optical fibers is important for students of physics due to increased applications of fiber optics in today’s technological world. In an effort to devise new activities to study such fibers, we obtained samples of wavelength-shifting WLS optical fibers, used in construction of research-grade particle detectors. Qualitative experiments in our laboratories examined how these fibers interact with various colors of visible light. From these results, student activities were developed to increase critical thinking in introductory physics courses and to facilitate students’ progression from traditional-classroom to research-oriented settings.

  11. Improved optical performance monitoring technique based on nonlinear optics for high-speed WDM Nyquist systems

    Science.gov (United States)

    Guesmi, Latifa; Menif, Mourad

    2016-04-01

    The field of fiber optics nonlinearity is more discussed last years due to such remarkable enhancement in the nonlinear processes efficiency. In this paper, and for optical performance monitoring (OPM), a new achievement of nonlinear effects has been investigated. The use of cross-phase modulation (XPM) and four-wave mixing (FWM) effects between input optical signal and inserted continuous-wave probe has proposed for impairments monitoring. Indeed, transmitting a multi-channels phase modulated signal at high data rate (1 Tbps WDM Nyquist NRZ- DP-QPSK) improves the sensitivity and the dynamic range monitoring. It was observed by simulation results that various optical parameters including optical power, wavelength, chromatic dispersion (CD), polarization mode dispersion (PMD), optical signal-to-noise ratio (OSNR), Q-factor and so on, can be monitored. Also, the effect of increasing the channel spacing between WDM signals is studied and proved its use for FWM power monitoring.

  12. Optical Processing of High Dimensionality Signals

    DEFF Research Database (Denmark)

    Da Ros, Francesco

    signal processing, including wavelength conversion, optical phase conjugation (OPC), and signal regeneration. This project focuses precisely on the applications of OPAs for all-optical signal processing with a two-fold focus: on the one hand, processing the advanced modulation formats required......) waveguides, are investigated. The limits of parametric amplification for 16-quadrature amplitude modulation (QAM) signals are first characterized. The acquired knowledge is then applied to the design of a black-box OPC-device used to provide Kerr nonlinearity compensation for a 5-channel polarization......-division multiplexing (PDM) 16-QAM signal at 1.12 Tbps with significant improvements in received signal quality. Furthermore, the first demonstration of phase regeneration for binary phase-shift keying (BPSK) signals using the silicon platform is presented. The silicon-based OPA relies on a novel design where a reverse...

  13. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    Science.gov (United States)

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-01-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors. PMID:27456691

  14. Highly efficient metallic optical incouplers for quantum well infrared photodetectors

    Science.gov (United States)

    Liu, Long; Chen, Yu; Huang, Zhong; Du, Wei; Zhan, Peng; Wang, Zhenlin

    2016-07-01

    Herein, we propose a highly efficient metallic optical incoupler for a quantum well infrared photodetector (QWIP) operating in the spectrum range of 14~16 μm, which consists of an array of metal micropatches and a periodically corrugated metallic back plate sandwiching a semiconductor active layer. By exploiting the excitations of microcavity modes and hybrid spoof surface plasmons (SSPs) modes, this optical incoupler can convert infrared radiation efficiently into the quantum wells (QWs) layer of semiconductor region with large electrical field component (Ez) normal to the plane of QWs. Our further numerical simulations for optimization indicate that by tuning microcavity mode to overlap with hybrid SSPs mode in spectrum, a coupled mode is formed, which leads to 33-fold enhanced light absorption for QWs centered at wavelength of 14.5 μm compared with isotropic absorption of QWs without any metallic microstructures, as well as a large value of coupling efficiency (η) of |Ez|2 ~ 6. This coupled mode shows a slight dispersion over ~40° and weak polarization dependence, which is quite beneficial to the high performance infrared photodetectors.

  15. Optical transmission of PMMA optical fibres exposed to high intensity UVA and visible blue light

    Science.gov (United States)

    Alobaidani, A. D.; Furniss, D.; Johnson, M. S.; Endruweit, A.; Seddon, A. B.

    2010-05-01

    Optical transmission of PMMA (polymethylmethacrylate) POF (polymer optical fibre) in the spectral range from 280 to 450 nm is investigated with a high radiation emission source comprising a mercury lamp delivering 40 W/cm 2 at the PMMA POF launch face. The heat generated from the radiation source causes a sudden drop in the launched radiation due to thermal-oxidation and photo-degradation of the launch face of the PMMA POF; this results in a loss of 53% of the total launched power within 13 min of exposure to the source. The thermal-oxidation degradation is controlled by a cooling device which improves the transmission stability of the fibre. However, photo-degradation is still active and causes a loss in power of 7% in 13 min. The spectral output of the transmitted radiation through the PMMA POF was monitored and indicates the variation in optical loss with wavelength. High rates of nominal absorption for the irradiated PMMA POF are found below 320 nm wavelength. From the Beer-Lambert law, the photo-degradation effect with time of a fixed path length of PMMA POF is described by the absorption coefficient ( αλ, cm -1) . The nominal absorption coefficient αλ values in the range 335-368 nm wavelength are found to be higher after 1 h of irradiation than the values in the range 406-438 nm. However, the relative change in the nominal absorption coefficient Δ αλ is greater at 438 nm than at 335 nm, 368 or 406 nm. After 1 h of irradiation with the cooling device in place, the PMMA POF transmission was reduced to 44.8% of its initial value; this recovered to a maximum of 86% of the original transmission of the total launched power after 5 weeks in ambient conditions.

  16. Design and performance of ultra-high-density optical fiber cable with rollable optical fiber ribbons

    Science.gov (United States)

    Hogari, Kazuo; Yamada, Yusuke; Toge, Kunihiro

    2010-08-01

    This paper proposes a novel ultra-high-density optical fiber cable that employs rollable optical fiber ribbons. The cable has great advantages in terms of cable weight and diameter, and fiber splicing workability. Moreover, it will be easy to install in a small space in underground ducts and on residential and business premises. The structural design of the rollable optical fiber ribbon is evaluated theoretically and experimentally, and an optimum adhesion pitch P in the longitudinal direction is obtained. In addition, we examined the performance of ultra-high-density cables with a small diameter that employ rollable optical fiber ribbons and bending-loss insensitive optical fibers. The transmission, mechanical and mid-span access performance of these cables was confirmed to be excellent.

  17. Depth profilometry via multiplexed optical high-coherence interferometry

    National Research Council Canada - National Science Library

    Kazemzadeh, Farnoud; Wong, Alexander; Behr, Bradford B; Hajian, Arsen R

    2015-01-01

    ... such as defect detection, corrosion assessment, and dental assessment to name a few. In this study, we investigate the feasibility of depth profilometry using an Multiplexed Optical High-coherence Interferometry MOHI instrument...

  18. Decay of high order optical vortices in anisotropic nonlinear optical media

    DEFF Research Database (Denmark)

    Mamaev, A.V.; Saffman, M.; Zozulya, A.A.

    1997-01-01

    We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge.......We present an experimental and theoretical study of the decay of high order optical vortices in media with an anisotropic nonlocal nonlinearity. Vortices with charge n decay into an aligned array of n vortices of unit charge....

  19. Magneto-optical system for high speed real time imaging

    Science.gov (United States)

    Baziljevich, M.; Barness, D.; Sinvani, M.; Perel, E.; Shaulov, A.; Yeshurun, Y.

    2012-08-01

    A new magneto-optical system has been developed to expand the range of high speed real time magneto-optical imaging. A special source for the external magnetic field has also been designed, using a pump solenoid to rapidly excite the field coil. Together with careful modifications of the cryostat, to reduce eddy currents, ramping rates reaching 3000 T/s have been achieved. Using a powerful laser as the light source, a custom designed optical assembly, and a high speed digital camera, real time imaging rates up to 30 000 frames per seconds have been demonstrated.

  20. Application of Beyond Bound Decoding for High Speed Optical Communications

    DEFF Research Database (Denmark)

    Li, Bomin; Larsen, Knud J.; Vegas Olmos, Juan José;

    2013-01-01

    This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB.......This paper studies the application of beyond bound decoding method for high speed optical communications. This hard-decision decoding method outperforms traditional minimum distance decoding method, with a total net coding gain of 10.36 dB....

  1. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu;

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  2. Development of large aperture elements for active and adaptive optics

    Directory of Open Access Journals (Sweden)

    Stranakova E.

    2013-05-01

    Full Text Available Large-aperture elements for laser active and adaptive optics are investigated in collaboration within IOP AcSci CR, FEng CTU and 5M. A bimorph deformable mirror for high-power lasers based on a lightweight structure with a composite core is currently in development. In order to realize a sufficiently large working aperture we are using new technologies for production of core, bimorph actuator and DM reflector. Detailed simulation of components and structure is validated by measurement and testing. A research of DM actuation and response of a complicated mirror structure needed for an accurate control of a deformation is performed. Testing of samples and subscale measurements are currently performed, measurement of a complete structure is in preparation.

  3. Reverberation Mapping of Optical Emission Lines in Five Active Galaxies

    CERN Document Server

    Fausnaugh, M M; Bentz, M C; Denney, K D; De Rosa, G; Peterson, B M; Kochanek, C S; Pogge, R W; Adams, S M; Barth, A J; Beatty, Thomas G; Bhattacharjee, A; Borman, G A; Boroson, T A; Bottorff, M C; Brown, Jacob E; Brown, Jonathan S; Brotherton, M S; Coker, C T; Crawford, S M; Croxall, K V; Eftekharzadeh, Sarah; Eracleous, Michael; Joner, M D; Henderson, C B; Holoien, T W -S; Horne, Keith; Hutchison, T; Kaspi, Shai; Kim, S; King, Anthea L; Li, Miao; Lochhaas, Cassandra; Ma, Zhiyuan; MacInnis, F; Manne-Nicholas, E R; Mason, M; Montuori, Carmen; Mosquera, Ana; Mudd, Dale; Musso, R; Nazarov, S V; Nguyen, M L; Okhmat, D N; Onken, Christopher A; Ou-Yang, B; Pancoast, A; Pei, L; Penny, Matthew T; Poleski, Radoslaw; Rafter, Stephen; Romero-Colmenero, E; Runnoe, Jessie; Sand, David J; Schimoia, Jaderson S; Sergeev, S G; Shappee, B J; Simonian, Gregory V; Somers, Garrett; Spencer, M; Starkey, D; Stevens, Daniel J; Tayar, Jamie; Treu, T; Valenti, Stefano; Van Saders, J; Villanueva, S; Villforth, C; Weiss, Yaniv; Winkler, H; Zhu, W

    2016-01-01

    We present the first results from an optical reverberation mapping campaign executed in 2014, targeting the active galactic nuclei (AGN) MCG+08-11-011, NGC 2617, NGC 4051, 3C 382, and Mrk 374. Our targets have diverse and interesting observational properties, including a "changing look" AGN and a broad-line radio galaxy. Based on continuum-H$\\beta$ lags, we measure black hole masses for all five targets. We also obtain H$\\gamma$ and He{\\sc ii}\\,$\\lambda 4686$ lags for all objects except 3C 382. The He{\\sc ii}\\,$\\lambda 4686$ lags indicate radial stratification of the BLR, and the masses derived from different emission lines are in general agreement. The relative responsivities of these lines are also in qualitative agreement with photoionization models. These spectra have extremely high signal-to-noise ratios (100--300 per pixel) and there are excellent prospects for obtaining velocity-resolved reverberation signatures.

  4. New Architecture of Optical Interconnect for High-Speed Optical Computerized Data Networks (Nonlinear Response

    Directory of Open Access Journals (Sweden)

    El-Sayed A. El-Badawy

    2008-02-01

    Full Text Available Although research into the use of optics in computers has increased in the last and current decades, the fact remains that electronics is still superior to optics in almost every way. Research into the use of optics at this stage mirrors the research into electronics after the 2nd World War. The advantages of using fiber optics over wiring are the same as the argument for using optics over electronics in computers. Even through totally optical computers are now a reality, computers that combine both electronics and optics, electro-optic hybrids, have been in use for some time. In the present paper, architecture of optical interconnect is built up on the bases of four Vertical-Cavity Surface- Emitting Laser Diodes (VCSELD and two optical links where thermal effects of both the diodes and the links are included. Nonlinear relations are correlated to investigate the power-current and the voltage-current dependences of the four devices. The good performance (high speed of the interconnect is deeply and parametrically investigated under wide ranges of the affecting parameters. The high speed performance is processed through three different effects, namely the device 3-dB bandwidth, the link dispersion characteristics, and the transmitted bit rate (soliton. Eight combinations are investigated; each possesses its own characteristics. The best architecture is the one composed of VCSELD that operates at 850 nm and the silica fiber whatever the operating set of causes. This combination possesses the largest device 3-dB bandwidth, the largest link bandwidth and the largest soliton transmitted bit rate. The increase of the ambient temperature reduces the high-speed performance of the interconnect

  5. New Architecture of Optical Interconnect for High-Speed Optical Computerized Data Networks (Nonlinear Response

    Directory of Open Access Journals (Sweden)

    El-Sayed A. El-Badawy

    2008-02-01

    Full Text Available Although research into the use of optics in computers has increased in the last and current decades, the fact remains that electronics is still superior to optics in almost every way. Research into the use of optics at this stage mirrors the research into electronics after the 2nd World War. The advantages of using fiber optics over wiring are the same as the argument for using optics over electronics in computers. Even through totally optical computers are now a reality, computers that combine both electronics and optics, electro-optic hybrids, have been in use for some time. In the present paper, architecture of optical interconnect is built up on the bases of four Vertical-Cavity Surface- Emitting Laser Diodes (VCSELD and two optical links where thermal effects of both the diodes and the links are included. Nonlinear relations are correlated to investigate the power-current and the voltage-current dependences of the four devices. The good performance (high speed of the interconnect is deeply and parametrically investigated under wide ranges of the affecting parameters. The high speed performance is processed through three different effects, namely the device 3-dB bandwidth, the link dispersion characteristics, and the transmitted bit rate (soliton. Eight combinations are investigated; each possesses its own characteristics. The best architecture is the one composed of VCSELD that operates at 850 nm and the silica fiber whatever the operating set of causes. This combination possesses the largest device 3-dB bandwidth, the largest link bandwidth and the largest soliton transmitted bit rate. The increase of the ambient temperature reduces the high-speed performance of the interconnect

  6. Calculations for the Pre-Calibration of LAMOST Active Optics

    Institute of Scientific and Technical Information of China (English)

    Yong Zhang; Xiang-Qun Cui

    2005-01-01

    Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) is one of the major on-going national large scientific projects in China.Active optics is a key technology for the LAMOST with which the thin-mirror active optics and segmented-mirror active optics are tied in. A pre-calibration method considering all active forces and displacements specially for LAMOST has been developed in early 2004. We give a detailed mathematical derivation and calculation including numerical simulation and computer program realization of the pre-calibration method of LAMOST open-loop control for the third-order aspherical aberration. We have also carried out calculations on the application of the pre-calibration method and the parameters of actuator design in LAMOST active optics in observation mode, including estimations of the actuator ranges,the interval of active optics correction and the ranges and trends of load changes on all the actuators during LAMOST tracking a given star.

  7. Optical response and activity of ultrathin films of topological insulators

    Science.gov (United States)

    Parhizgar, Fariborz; Moghaddam, Ali G.; Asgari, Reza

    2015-07-01

    We investigate the optical properties of ultrathin film of a topological insulator in the presence of an in-plane magnetic field. We show that due to the combination of the overlap between the surface states of the two layers and the magnetic field, the optical conductivity can show strong anisotropy. This leads to the effective optical activity of the ultrathin film by influencing the circularly polarized incident light. Intriguingly, for a range of magnetic fields, the reflected and transmitted lights exhibit elliptic character. Even for certain values almost linear polarizations are obtained, indicating that the thin film can act as a polaroid in reflection. All these features are discussed in the context of the time-reversal symmetry breaking as one of the key ingredients for the optical activity.

  8. Active stabilization of the optical part in fiber optic quantum cryptography

    Science.gov (United States)

    Balygin, K. A.; Klimov, A. N.; Kulik, S. P.; Molotkov, S. N.

    2016-03-01

    The method of active stabilization of the polarization and other parameters of the optical part of a two-pass fiber optic quantum cryptography has been proposed and implemented. The method allows the completely automated maintenance of the visibility of interference close to an ideal value ( V ≥ 0.99) and the reduction of the instrumental contribution to the error in primary keys (QBER) to 0.5%.

  9. Influence of load by high power on the optical coupler

    Science.gov (United States)

    Bednarek, Lukas; Poboril, Radek; Vanderka, Ales; Hajek, Lukas; Nedoma, Jan; Vasinek, Vladimir

    2016-12-01

    Nowadays, aging of the optical components is a very current topic. Therefore, some investigations are focused on this area, so that the aging of the optical components is accelerated by thermal, high power and gamma load. This paper deals by findings of the influence of the load by laser with high optical power on the transmission parameters of the optical coupler. The investigated coupler has one input and eight outputs (1x8). Load by laser with high optical power is realized using a fiber laser with a cascade configuration EDFA amplifiers. The output power of the amplifier is approximately 250 mW. Duration of the load is moving from 104 hours to 139 hours. After each load, input power and output powers of all branches are measured. Following parameters of the optical coupler are calculated using formulas: the insertion losses of the individual branches, split ratio, total losses, homogeneity of the losses and cross-talk between different branches. All measurements are performed at wavelengths 1310 nm and 1550 nm. Individual optical powers are measured 20 times, due to the exclusion of statistical error of the measurement. After measuring, the coupler is connected to the amplifier for next cycle of the load. The paper contains an evaluation of the results of the coupler before and after four cycles of the burden.

  10. Ultra-high-speed Optical Signal Processing using Silicon Photonics

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Ji, Hua; Jensen, Asger Sellerup

    on silicon photonics. In particular we use nano-engineered silicon waveguides (nanowires) [1] enabling efficient phasematched four-wave mixing (FWM), cross-phase modulation (XPM) or self-phase modulation (SPM) for ultra-high-speed optical signal processing of ultra-high bit rate serial data signals. We show......— In supercomputers, the optical inter-connects are getting closer and closer to the processing cores. Today, a single supercomputer system has as many optical links as the whole worldwide web together, and it is envisaged that future computing chips will contain multiple electronic processor cores...... with a photonic layer on top to interconnect them. For such systems, silicon is an attractive candidate enabling both electronic and photonic control. For some network scenarios, it may be beneficial to use optical on-chip packet switching, and for high data-density environments one may take advantage...

  11. The simulation study on optical target laser active detection performance

    Science.gov (United States)

    Li, Ying-chun; Hou, Zhao-fei; Fan, Youchen

    2014-12-01

    According to the working principle of laser active detection system, the paper establishes the optical target laser active detection simulation system, carry out the simulation study on the detection process and detection performance of the system. For instance, the performance model such as the laser emitting, the laser propagation in the atmosphere, the reflection of optical target, the receiver detection system, the signal processing and recognition. We focus on the analysis and modeling the relationship between the laser emitting angle and defocus amount and "cat eye" effect echo laser in the reflection of optical target. Further, in the paper some performance index such as operating range, SNR and the probability of the system have been simulated. The parameters including laser emitting parameters, the reflection of the optical target and the laser propagation in the atmosphere which make a great influence on the performance of the optical target laser active detection system. Finally, using the object-oriented software design methods, the laser active detection system with the opening type, complete function and operating platform, realizes the process simulation that the detection system detect and recognize the optical target, complete the performance simulation of each subsystem, and generate the data report and the graph. It can make the laser active detection system performance models more intuitive because of the visible simulation process. The simulation data obtained from the system provide a reference to adjust the structure of the system parameters. And it provides theoretical and technical support for the top level design of the optical target laser active detection system and performance index optimization.

  12. Actively Pumped Optical Filters at 532 nm

    Science.gov (United States)

    Billmers, Richard I.; Gayen, S. K.; Contarino, Vincent M.; Scharpf, William J.; Squicciarini, Martin F.; Allocca, David A.

    1995-01-01

    The operation of two narrow-band optical filters at 532.33 nm is presented. Both of these filters operate on the 4P(sub 1/2) to 8S(sub 1/2) excited-state transition in potassium vapor. One of the filters is based on excited-state Faraday effect, and requires the application of an external axial magnetic field. The peak transmission of this filter is approximately 3.5% with a linewidth of less than 10 GHz. The second filter does not require a magnetic field for its operation, but readily attains peak transmissions of 25-30%. The 4P(sub 1/2) state is excited by a 769.9 nm light pulse which is linearly polarized for the first scheme and circularly polarized for the second.

  13. All-optical high performance graphene-photonic crystal switch

    Science.gov (United States)

    Hoseini, Mehrdad; Malekmohammad, Mohammad

    2017-01-01

    The all-optical switch is realized based on nonlinear transmission changes in Fano resonance of 2D photonic crystals (PhC) which enhances the light intensity on the graphene in PhC; and in this study, the graphene layer is used as the nonlinear material. The refractive index change of graphene layer leads to a shift in the Fano resonance frequency due to the input light intensity through the Kerr nonlinear effect. Through finite-difference time-domain simulation, it is found that the high performance of all-optical switching can be achieved by the designed structure with a threshold pump intensity as low as MW/cm2. This structure is featured by optical bistability. The obtained results are applicable in micro optical integrated circuits for modulators, switches and logic elements for optical computation.

  14. Ultra-high Frequency Linear Fiber Optic Systems

    CERN Document Server

    Lau, Kam

    2011-01-01

    This book provides an in-depth treatment of both linear fiber-optic systems and their key enabling devices. It presents a concise but rigorous treatment of the theory and practice of analog (linear) fiber-optics links and systems that constitute the foundation of Hybrid Fiber Coax infrastructure in present-day CATV distribution and cable modem Internet access. Emerging applications in remote fiber-optic feed for free-space millimeter wave enterprise campus networks are also described. Issues such as dispersion and interferometric noise are treated quantitatively, and means for mitigating them are explained. This broad but concise text will thus be invaluable not only to students of fiber-optics communication but also to practicing engineers. To the second edition of this book important new aspects of linear fiber-optic transmission technologies are added, such as high level system architectural issues, algorithms for deriving the optimal frequency assignment, directly modulated or externally modulated laser t...

  15. Active Learning Strategies for Introductory Light and Optics

    Science.gov (United States)

    Sokoloff, David R.

    2016-01-01

    There is considerable evidence that traditional approaches are ineffective in teaching physics concepts, including light and optics concepts. A major focus of the work of the Activity Based Physics Group has been on the development of active learning curricula like RealTime Physics (RTP) labs and Interactive Lecture Demonstrations (ILDs). Among…

  16. The in vivo activation of persistent nanophosphors for optical imaging of vascularization, tumours and grafted cells

    Science.gov (United States)

    Maldiney, Thomas; Bessière, Aurélie; Seguin, Johanne; Teston, Eliott; Sharma, Suchinder K.; Viana, Bruno; Bos, Adrie J. J.; Dorenbos, Pieter; Bessodes, Michel; Gourier, Didier; Scherman, Daniel; Richard, Cyrille

    2014-04-01

    Optical imaging for biological applications requires more sensitive tools. Near-infrared persistent luminescence nanoparticles enable highly sensitive in vivo optical detection and complete avoidance of tissue autofluorescence. However, the actual generation of persistent luminescence nanoparticles necessitates ex vivo activation before systemic administration, which prevents long-term imaging in living animals. Here, we introduce a new generation of optical nanoprobes, based on chromium-doped zinc gallate, whose persistent luminescence can be activated in vivo through living tissues using highly penetrating low-energy red photons. Surface functionalization of this photonic probe can be adjusted to favour multiple biomedical applications such as tumour targeting. Notably, we show that cells can endocytose these nanoparticles in vitro and that, after intravenous injection, we can track labelled cells in vivo and follow their biodistribution by a simple whole animal optical detection, opening new perspectives for cell therapy research and for a variety of diagnosis applications.

  17. Recent progress on high-speed optical transmission

    Directory of Open Access Journals (Sweden)

    Jianjun Yu

    2016-05-01

    Full Text Available The recently reported high spectral efficiency (SE and high-baud-rate signal transmission are all based on digital coherent optical communications and digital signal processing (DSP. DSP simplifies the reception of advanced modulation formats and also enables the major electrical and optical impairments to be processed and compensated in the digital domain, at the transmitter or receiver side. In this paper, we summarize the research progress on high-speed signal generation and detection and also show the progress on DSP for high-speed signal detection. We also report the latest progress on multi-core and multi-mode multiplexing.

  18. Optical sensing in high voltage transmission lines using power over fiber and free space optics

    Science.gov (United States)

    Rosolem, João Batista; Bassan, Fabio Renato; Penze, Rivael Strobel; Leonardi, Ariovaldo Antonio; Fracarolli, João Paulo Vicentini; Floridia, Claudio

    2015-12-01

    In this work we propose the use of power over fiber (PoF) and free space optics (FSO) techniques to powering and receive signals from an electrical current sensor placed at high voltage potential using a pair of optical collimators. The technique evaluation was performed in a laboratorial prototype using 62.5/125 μm multimode fiber to study the sensitivity of the optical alignment and the influence of the collimation process in the sensing system wavelengths: data communication (1310 nm) and powering (830 nm). The collimators were installed in a rigid electric insulator in order to maintain the stability of transmission.

  19. Peptide-modified optical filters for detecting protease activity.

    Science.gov (United States)

    Kilian, Kristopher A; Böcking, Till; Gaus, Katharina; Gal, Michael; Gooding, J Justin

    2007-11-01

    The organic derivatization of silicon-based nanoporous photonic crystals is presented as a method to immobilize peptides for the detection of protease enzymes in solution. A narrow-line-width rugate filter, a one-dimensional photonic crystal, is fabricated that exhibits a high-reflectivity optical resonance that is sensitive to small changes in the refractive index at the pore walls. To immobilize peptide in the pore of the photonic crystal, the hydrogen-terminated silicon surface was first modified with the alkene 10-succinimidyl undecenoate via hydrosilylation. The monolayer with the succinimide ester moiety at the distal end served the dual function of protecting the underlying silicon from oxidation as well as providing a surface suitable for subsequent derivatization with amines. The surface was further modified with 1-aminohexa(ethylene glycol) (EG(6)) to resist nonspecific adsorption of proteins common in complex biological samples. The distal hydroxyl of the EG(6) is activated using the solid-phase coupling reagent disuccinimidyl carbonate for selective immobilization of peptides as protease recognition elements. X-ray photoelectron spectroscopy analysis reveals high activation and coupling efficiency at each stage of the functionalization. Exposure of the peptide-modified crystals to the protease subtilisin in solution causes a change in the refractive index, resulting in a shift of the resonance to shorter wavelengths, indicating cleavage of organic material within the pores. The lowest detected concentration of enzyme was 37 nM (7.4 pmol in 200 microL).

  20. Second Approximation Model for Optical Head in Super High Density Storage Technology

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The paper presents second approximation model for optical head in super high-density storage technology firstly and it is an important part for three grades approximate model of ultra-small-size quantum well corn-shaped laser and simulative calculations. It supplies the important and useful results for the NFOD optical head design with ultra thin active layer and ultra small spot laser.

  1. High-throughput proteomics : optical approaches.

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, George S.

    2008-09-01

    Realistic cell models could greatly accelerate our ability to engineer biochemical pathways and the production of valuable organic products, which would be of great use in the development of biofuels, pharmaceuticals, and the crops for the next green revolution. However, this level of engineering will require a great deal more knowledge about the mechanisms of life than is currently available. In particular, we need to understand the interactome (which proteins interact) as it is situated in the three dimensional geometry of the cell (i.e., a situated interactome), and the regulation/dynamics of these interactions. Methods for optical proteomics have become available that allow the monitoring and even disruption/control of interacting proteins in living cells. Here, a range of these methods is reviewed with respect to their role in elucidating the interactome and the relevant spatial localizations. Development of these technologies and their integration into the core competencies of research organizations can position whole institutions and teams of researchers to lead in both the fundamental science and the engineering applications of cellular biology. That leadership could be particularly important with respect to problems of national urgency centered around security, biofuels, and healthcare.

  2. Exploring the origin of high optical absorption in conjugated polymers

    KAUST Repository

    Vezie, Michelle S.

    2016-05-16

    The specific optical absorption of an organic semiconductor is critical to the performance of organic optoelectronic devices. For example, higher light-harvesting efficiency can lead to higher photocurrent in solar cells that are limited by sub-optimal electrical transport. Here, we compare over 40 conjugated polymers, and find that many different chemical structures share an apparent maximum in their extinction coefficients. However, a diketopyrrolopyrrole-thienothiophene copolymer shows remarkably high optical absorption at relatively low photon energies. By investigating its backbone structure and conformation with measurements and quantum chemical calculations, we find that the high optical absorption can be explained by the high persistence length of the polymer. Accordingly, we demonstrate high absorption in other polymers with high theoretical persistence length. Visible light harvesting may be enhanced in other conjugated polymers through judicious design of the structure.

  3. Optical levitation of high purity nanodiamonds in vacuum without heating

    CERN Document Server

    Frangeskou, A C; Gines, L; Mandal, S; Williams, O A; Barker, P F; Morley, G W

    2016-01-01

    Levitated nanodiamonds containing nitrogen vacancy centres in high vacuum are a potential test bed for numerous phenomena in fundamental physics. However, experiments so far have been limited to low vacuum due to heating arising from optical absorption of the trapping laser. We show that milling pure diamond creates nanodiamonds that do not heat up as the optical intensity is raised above 700 GW/m$^2$ below 5 mbar of pressure. This advance now means that the level of attainable vacuum for nanodiamonds in optical dipole traps is no longer temperature limited.

  4. Research of high speed optical switch based on compound semiconductor

    Institute of Scientific and Technical Information of China (English)

    WANG MingHua; QI Wei; YU Hui; JIANG XiaoQing; YANG JianYi

    2009-01-01

    High-speed optical switch and its array are the crucial components of all-optical switching system. This paper presents the analytical model of a total-internal-reflection (TIR) optical switch. By employing the carrier injection effect in GaAs and the GaAs/AlGaAs double heterojunction structure, the X-junction TIR switch and the Mach-Zehnder interference (MZI) switch are demonstrated at 1.55 IJm. The measured results show that the extinction ratio of both switches exceeds 20 dB. The switching speed reaches the scale of 10 ns.

  5. High-speed image matching with coaxial holographic optical correlator

    Science.gov (United States)

    Ikeda, Kanami; Watanabe, Eriko

    2016-09-01

    A computation speed of more than 100 Gbps is experimentally demonstrated using our developed ultrahigh-speed optical correlator. To verify this high computation speed practically, the computation speeds of our optical correlator and conventional digital image matching are quantitatively compared. We use a population count function that achieves the fastest calculation speed when calculating binary matching by a central processing unit (CPU). The calculation speed of the optical correlator is dramatically faster than that using a CPU (2.40 GHz × 4) and 16 GB of random access memory, especially when the calculation data are large-scale.

  6. Soliton-based ultra-high speed optical communications

    Indian Academy of Sciences (India)

    Akira Hasegawa

    2001-11-01

    Multi-terabit/s, ultra-high speed optical transmissions over several thousands kilometers on fibers are becoming a reality. Most use RZ (Return to Zero) format in dispersion-managed fibers. This format is the only stable waveform in the presence of fiber Kerr nonlinearity and dispersion in all optical transmission lines with loss compensated by periodic amplifications. The nonlinear Schrödinger equation assisted by the split step numerical solutions is commonly used as the master equation to describe the information transfer in optical fibers. All these facts are the outcome of research on optical solitons in fibers in spite of the fact that the commonly used RZ format is not always called a soliton format. The overview presented here attempts to incorporate the role of soliton-based communications research in present day ultra-high speed communications.

  7. High-Order Modulation for Optical Fiber Transmission

    CERN Document Server

    Seimetz, Matthias

    2009-01-01

    Catering to the current interest in increasing the spectral efficiency of optical fiber networks by the deployment of high-order modulation formats, this monograph describes transmitters, receivers and performance of optical systems with high-order phase and quadrature amplitude modulation. In the first part of the book, the author discusses various transmitter implementation options as well as several receiver concepts based on direct and coherent detection, including designs of new structures. Hereby, both optical and electrical parts are considered, allowing the assessment of practicability and complexity. In the second part, a detailed characterization of optical fiber transmission systems is presented, regarding a wide range of modulation formats. It provides insight in the fundamental behavior of different formats with respect to relevant performance degradation effects and identifies the major trends in system performance.

  8. Synthesis of high purity metal oxide nanoparticles for optical applications

    Science.gov (United States)

    Baker, C.; Kim, W.; Friebele, E. J.; Villalobos, G.; Frantz, J.; Shaw, L. B.; Sadowski, B.; Fontana, J.; Dubinskii, M.; Zhang, J.; Sanghera, J.

    2014-09-01

    In this paper we present our recent research results in synthesizing various metal oxide nanoparticles for use as laser gain media (solid state as well as fiber lasers) and transparent ceramic windows via two separate techniques, co-precipitation and flame spray pyrolysis. The nanoparticles were pressed into ceramic discs that exhibited optical transmission approaching the theoretical limit and showed very high optical-to-optical lasing slope efficiency. We have also synthesized sesquioxide nanoparticles using a Flame Spray Pyrolysis (FSP) technique that leads to the synthesis of a metastable phase of sesquioxide which allows fabricating excellent optical quality transparent windows with very fine grain sizes. Finally, we present our research in the synthesis of rare earth doped boehmite nanoparticles where the rareearth ion is encased in a cage of aluminum and oxygen to prevent ion-ion proximity and energy transfer. The preforms have been drawn into fibers exhibiting long lifetimes and high laser efficiencies.

  9. High speed nonlinear optical components for next-generation optical communications

    OpenAIRE

    Cleary, Ciaran Sean

    2013-01-01

    Electronic signal processing systems currently employed at core internet routers require huge amounts of power to operate and they may be unable to continue to satisfy consumer demand for more bandwidth without an inordinate increase in cost, size and/or energy consumption. Optical signal processing techniques may be deployed in next-generation optical networks for simple tasks such as wavelength conversion, demultiplexing and format conversion at high speed (≥100Gb.s-1) to alleviate the pres...

  10. HIGH-STABLE ERBIUM SUPERLUMINESCENT FIBER OPTICAL SOURCES CREATION METHODS

    Directory of Open Access Journals (Sweden)

    A. S. Aleynik

    2016-07-01

    Full Text Available We present the overview of wideband Erbium doped superluminescent fiber sources (EDSFS creation methods. This type of optical sources is mainly used in navigation accuracy class fiber-optical gyroscopes (FOG production. For this application an optical source should have small coherence length to reduce FOG output signal error rate. Output signal errors are caused by different parasitic effects: reverse Rayleigh scattering, optical components mode swapping, Kerr effect. Consequently, the most important characteristics of EDSFS are central wavelength time and wide temperature range stability and optical spectrum width and shape. The spectrum shape is needed to be close to the Gaussian distribution to minimize time coherence function. The paper deals with major EDSFS instability reasons and their most effective spectral parameters stabilization and optimization methods. We consider various methods of output optical radiation spectrum correction, and problems connected with output radiation residual polarization, the EDSFS principle of operation, structure and their basic construction schemes, the overview of Erbium-doped active fibers for EDSFS creation. The conclusions on most effective output optical radiation stabilization methods are drawn.

  11. Influence of optical activity on rogue waves propagating in chiral optical fibers

    Science.gov (United States)

    Temgoua, D. D. Estelle; Kofane, T. C.

    2016-06-01

    We derive the nonlinear Schrödinger (NLS) equation in chiral optical fiber with right- and left-hand nonlinear polarization. We use the similarity transformation to reduce the generalized chiral NLS equation to the higher-order integrable Hirota equation. We present the first- and second-order rational solutions of the chiral NLS equation with variable and constant coefficients, based on the modified Darboux transformation method. For some specific set of parameters, the features of chiral optical rogue waves are analyzed from analytical results, showing the influence of optical activity on waves. We also generate the exact solutions of the two-component coupled nonlinear Schrödinger equations, which describe optical activity effects on the propagation of rogue waves, and their properties in linear and nonlinear coupling cases are investigated. The condition of modulation instability of the background reveals the existence of vector rogue waves and the number of stable and unstable branches. Controllability of chiral optical rogue waves is examined by numerical simulations and may bring potential applications in optical fibers and in many other physical systems.

  12. High directivity optical antenna substrates for surface enhanced Raman scattering.

    Science.gov (United States)

    Wang, Dongxing; Zhu, Wenqi; Chu, Yizhuo; Crozier, Kenneth B

    2012-08-22

    A two-dimensional array of gold optical antennas integrated with a one-dimensional array of gold strips and mirrors is introduced and fabricated. The experimental results show that this design achieves average surface-enhanced Raman scattering (SERS) enhancement factors as high as 1.2 × 10(10) , which is more than two orders of magnitude larger than optical antennas without the gold strips and gold mirror.

  13. Electrophoretic High Molecular Weight DNA Purification Enables Optical Mapping

    OpenAIRE

    Maydan, Jason; THOMAS, Matthew; Tabanfar, Leyla; Mai, Laura; Poon, Hau-Ling; Pe, Joel; HAHN, KRISTEN; Goji, Noriko; Amoako, Kingsley; Marziali, Andre; Hanson, Dan

    2013-01-01

    Optical mapping generates an ordered restriction map from single, long DNA molecules. By overlapping restriction maps from multiple molecules, a physical map of entire chromosomes and genomes is constructed, greatly facilitating genome assembly in next generation sequencing projects, comparative genomics and strain typing. However, optical mapping relies on a method of preparing high quality DNA >250 kb in length, which can be challenging from some organisms and sample types. Here we demonstr...

  14. TOPICAL REVIEW: Optics of high-performance electron microscopes

    OpenAIRE

    H H Rose

    2008-01-01

    During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by...

  15. High Average Power Optical FEL Amplifiers

    CERN Document Server

    Ben-Zvi, I; Litvinenko, V

    2005-01-01

    Historically, the first demonstration of the FEL was in an amplifier configuration at Stanford University. There were other notable instances of amplifying a seed laser, such as the LLNL amplifier and the BNL ATF High-Gain Harmonic Generation FEL. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance a 100 kW average power FEL. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting energy recovery linacs combine well with the high-gain FEL amplifier to produce unprecedented average power FELs with some advantages. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Li...

  16. Polarized Raman optical activity of menthol and related molecules

    Science.gov (United States)

    Barron, L. D.; Hecht, L.; Blyth, S. M.

    1989-01-01

    Polarized and depolarized Raman optical activity spectra of menthol, menthyl chloride, neomenthol and neothiomenthol from 800 to 1500 cm -1 are reported. Despite axial symmetry in all the bonds, the presence of the heteroatoms O or S seems to induce large deviations from the expected ratio of 2:1 between the polarized and depolarized Raman optical activity intensities, but Cl does not. These deviations might originate in large electric quadrupole contributions induced by excited state interactions involving O or S Rydberg p orbitals and valence orbitals on other parts of the molecule. Such interactions appear to undermine the bond polarizability theory of Raman intensities.

  17. Enhanced sensing of molecular optical activity with plasmonic nanohole arrays

    CERN Document Server

    Gorkunov, Maxim V; Kondratov, Alexey V

    2016-01-01

    Prospects of using metal hole arrays for the enhanced optical detection of molecular chirality in nanosize volumes are investigated. Light transmission through the holes filled with an optically active material is modeled and the activity enhancement by more than an order of magnitude is demonstrated. The spatial resolution of the chirality detection is shown to be of a few tens of nanometers. From comparing the effect in arrays of cylindrical holes and holes of complex chiral shape, it is concluded that the detection sensitivity is determined by the plasmonic near field enhancement. The intrinsic chirality of the arrays due to their shape appears to be less important.

  18. Mode profiling of optical fibers at high laser powers

    DEFF Research Database (Denmark)

    Nielsen, Peter Carøe; Pedersen, David Bue; Simonsen, R.B.

    2008-01-01

    This paper describes the development of a measuring equipment capable of analysing the beam profile at high optical powers emitted by delivery fibers used in manufacturing processes. Together with the optical delivery system, the output beam quality from the delivery fiber and the shape...... of the focused spot can be determined. The analyser is based on the principle of a rotating wire being swept though the laser beam, while the reflected signal is recorded [1]. By changing the incident angle of the rotating rod from 0° to 360° in relation to the fiber, the full profile of the laser beam...... is obtained. Choosing a highly reflective rod material and a sufficiently high rotation speed, these measurements can be done with high laser powers, without any additional optical elements between the fiber and analyzer. The performance of the analyzer was evaluated by coupling laser light into different...

  19. Ultra-high accuracy optical testing: creating diffraction-limitedshort-wavelength optical systems

    Energy Technology Data Exchange (ETDEWEB)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman,Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli,Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-08-03

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-{angstrom} and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date.

  20. High-resolution optical functional mapping of the human somatosensory cortex

    Directory of Open Access Journals (Sweden)

    Stefan P Koch

    2010-06-01

    Full Text Available Non-invasive optical imaging of brain function has been promoted in a number of fields in which functional magnetic resonance imaging (fMRI is limited due to constraints induced by the scanning environment. Beyond physiological and psychological research, bedside monitoring and neurorehabilitation may be relevant clinical applications that are yet little explored. A major obstacle to advocate the tool in clinical research is insufficient spatial resolution. Based on a multi-distance high-density optical imaging setup, we here demonstrate a dramatic increase in sensitivity of the method. We show that optical imaging allows for the differentiation between activations of single finger representations in the primary somatosensory cortex (SI. Methodologically our findings confirm results in a pioneering study by Zeff et al. (2007 and extend them to the homuncular organization of SI. After performing a motor task, 8 subjects underwent vibrotactile stimulation of the little finger and the thumb. We used a high-density diffuse-optical sensing array in conjunction with optical tomographic reconstruction. Optical imaging disclosed three discrete activation foci one for motor and 2 discrete foci for vibrotactile stimulation of the 1st and 5th finger respectively. The results were co-registered to the individual anatomical brain anatomy (MRI which confirmed the localization in the expected cortical gyri in 4 subjects. This advance in spatial resolution opens new perspectives to apply optical imaging in the research on plasticity notably in patients undergoing neurorehabilitation.

  1. Optical properties of active photonic materials

    OpenAIRE

    Zeng, Yong

    2007-01-01

    Because of the generation of polaritons, which are quasiparticles possessing the characteristics of both photonics and electronics, active photonic materials offer a possible solution to transfer electromagnetic energy below the diffraction limit and further increase the density of photonic integrated circuits. A theoretical investigation of these exciting materials is, therefore, very important for practical applications. Four different kinds of polaritons have been studied in this thesis, (...

  2. A highly sensitive optical detector for use in deep underwater.

    Science.gov (United States)

    Hanada, H.; Hayashino, T.; Ito, M.; Iwasaki, A.; Kawamorita, K.; Kawamoto, H.; Matsumoto, T.; Narita, S.; Takayama, T.; Tanaka, S.; Yamaguchi, A.; Aoki, T.; Mitsui, K.; Ohashi, Y.; Okada, A.; Fukawa, M.; Uehara, S.; Bolesta, J. W.; Gorham, P. W.; Kondo, S.; Learned, J. G.; Matsuno, S.; Mignard, M.; Mitiguy, R.; O'Connor, D. J.; Peterson, V. Z.; Roberts, A.; Rosen, M.; Stenger, V. J.; Takemori, D.; Wilkins, G.; Grieder, P. K. F.; Minkowski, P.; Kitamura, T.; Camerini, U.; Grogan, W.; Jaworski, M.; March, R.; Narita, T.; Nicklaus, D.

    1998-05-01

    The authors have developed an optical detector module for use in deep underwater experiments that will search for high-energy neutrinos from cosmic rays and astronomical sources. This module is sensitive to single photons, is operable under high pressure, functions automatically and is remotely controlled.

  3. Special issue on high-resolution optical imaging

    Science.gov (United States)

    Smith, Peter J. S.; Davis, Ilan; Galbraith, Catherine G.; Stemmer, Andreas

    2013-09-01

    The pace of development in the field of advanced microscopy is truly breath-taking, and is leading to major breakthroughs in our understanding of molecular machines and cell function. This special issue of Journal of Optics draws attention to a number of interesting approaches, ranging from fluorescence and imaging of unlabelled cells, to computational methods, all of which are describing the ever increasing detail of the dynamic behaviour of molecules in the living cell. This is a field which traditionally, and currently, demonstrates a marvellous interplay between the disciplines of physics, chemistry and biology, where apparent boundaries to resolution dissolve and living cells are viewed in ever more clarity. It is fertile ground for those interested in optics and non-conventional imaging to contribute high-impact outputs in the fields of cell biology and biomedicine. The series of articles presented here has been selected to demonstrate this interdisciplinarity and to encourage all those with a background in the physical sciences to 'dip their toes' into the exciting and dynamic discoveries surrounding cell function. Although single molecule super-resolution microscopy is commercially available, specimen preparation and interpretation of single molecule data remain a major challenge for scientists wanting to adopt the techniques. The paper by Allen and Davidson [1] provides a much needed detailed introduction to the practical aspects of stochastic optical reconstruction microscopy, including sample preparation, image acquisition and image analysis, as well as a brief description of the different variants of single molecule localization microscopy. Since super-resolution microscopy is no longer restricted to three-dimensional imaging of fixed samples, the review by Fiolka [2] is a timely introduction to techniques that have been successfully applied to four-dimensional live cell super-resolution microscopy. The combination of multiple high-resolution techniques

  4. Design of a high-quality optical conjugate structure in optical tweezers.

    Science.gov (United States)

    Hu, Chunguang; An, Ran; Zhang, Chengwei; Lei, Hai; Hu, Xiaodong; Li, Hongbin; Hu, Xiaotang

    2015-02-20

    We propose an approach to realize a high-quality optical conjugate of a piezo-driven mirror (PM) in optical tweezers. Misalignments between the optical beam and the steering center of the PM are analyzed mathematically. The decentrations in different directions cause different changes, either a position change of the conjugate plane or a spot variation of the beam during PM steering. On the other hand, these misalignment-introduced problems provide the information to check the assembling errors. Thus a wanted conjugate plane of the PM can be effectively and precisely achieved according to the detection signals. This approach is also available to deal with multifactor coupling error. At the end, the procedure for error analysis is given by testing homebuilt optical tweezers.

  5. Electrophoretic High Molecular Weight DNA Purification Enables Optical Mapping

    Science.gov (United States)

    Maydan, Jason; Thomas, Matthew; Tabanfar, Leyla; Mai, Laura; Poon, Hau-Ling; Pe, Joel; Hahn, Kristen; Goji, Noriko; Amoako, Kingsley; Marziali, Andre; Hanson, Dan

    2013-01-01

    Optical mapping generates an ordered restriction map from single, long DNA molecules. By overlapping restriction maps from multiple molecules, a physical map of entire chromosomes and genomes is constructed, greatly facilitating genome assembly in next generation sequencing projects, comparative genomics and strain typing. However, optical mapping relies on a method of preparing high quality DNA >250 kb in length, which can be challenging from some organisms and sample types. Here we demonstrate the ability of Boreal Genomics' Aurora instrument to provide pure, high molecular weight (HMW) DNA 250-1,100 kb in length, ideally suited for optical mapping. The Aurora performs electrophoretic DNA purification within an agarose gel in reusable cartridges, protecting long DNA molecules from shearing forces associated with liquid handling steps common to other purification methods. DNA can be purified directly from intact cells embedded and lysed within an agarose gel, preserving the highest molecular weight DNA possible while achieving exceptional levels of purity. The Aurora delivers DNA in a buffer solution, where DNA can be condensed and protected from shearing during recovery with a pipette. DNA is then returned to its regular coiled state by simple dilution prior to optical mapping. Here we present images showing HMW DNA purification taking place in the Aurora and subsequent images of single DNA molecules on OpGen's Argus® Optical Mapping System. Future work will focus on further optimizing Aurora HMW DNA purification to bias DNA recovery in favor of only the longest molecules in a sample, maximizing the benefits of optical mapping.

  6. High-energy nuclear optics of polarized particles

    CERN Document Server

    Baryshevsky, Vladimir G

    2012-01-01

    The various phenomena caused by refraction and diffraction of polarized elementary particles in matter have opened up a new research area in the particle physics: nuclear optics of polarized particles. Effects similar to the well-known optical phenomena such as birefringence and Faraday effects, exist also in particle physics, though the particle wavelength is much less than the distance between atoms of matter. Current knowledge of the quasi-optical effects, which exist for all particles in any wavelength range (and energies from low to extremely high), will enable us to investigate different properties of interacting particles (nuclei) in a new aspect. This pioneering book will provide detailed accounts of quasi-optical phenomena in the particle polarization, and will interest physicists and professionals in experimental particle physics.

  7. Thermal lensing compensation for AIGO high optical power test facility

    Science.gov (United States)

    Degallaix, Jérôme; Zhao, Chunnong; Ju, Li; Blair, David

    2004-03-01

    We present finite element modelling of thermal lensing occurring in an interferometer test mass. Our simulations include the thermo-optic effect and mechanical expansion of the optics. For the High Optical Power Test Facility (HOPTF) operated by the Australian International Gravitational Observatory (AIGO), the optical path length measured across the laser beam radius is 45 nm for 1.2 W absorbed power for the input sapphire test mass. The AIGO thermal lens is much stronger than the one in Advanced LIGO and will degrade the interferometer performance. Direct thermal compensation and the use of an external compensation plate were investigated to minimize thermal lensing consequences in the interferometer. For the AIGO situation, a fused silica external plate is the most practical solution to correct thermally induced wavefront distortions. The compensation plate requires lower thermal power than direct compensation and does not increase the test mass temperature.

  8. Thermal lensing compensation for AIGO high optical power test facility

    Energy Technology Data Exchange (ETDEWEB)

    Degallaix, Jerome [School of Physics, University of Western Australia, Stirling Highway, Crawley, WA 6009 (Australia); Zhao Chunnong [Computer and Information Science, Edith Cowan University, Mount Lawley, WA 6050 (Australia); Ju Li [School of Physics, University of Western Australia, Stirling Highway, Crawley, WA 6009 (Australia); Blair, David [School of Physics, University of Western Australia, Stirling Highway, Crawley, WA 6009 (Australia)

    2004-03-07

    We present finite element modelling of thermal lensing occurring in an interferometer test mass. Our simulations include the thermo-optic effect and mechanical expansion of the optics. For the High Optical Power Test Facility (HOPTF) operated by the Australian International Gravitational Observatory (AIGO), the optical path length measured across the laser beam radius is 45 nm for 1.2 W absorbed power for the input sapphire test mass. The AIGO thermal lens is much stronger than the one in Advanced LIGO and will degrade the interferometer performance. Direct thermal compensation and the use of an external compensation plate were investigated to minimize thermal lensing consequences in the interferometer. For the AIGO situation, a fused silica external plate is the most practical solution to correct thermally induced wavefront distortions. The compensation plate requires lower thermal power than direct compensation and does not increase the test mass temperature.

  9. Strain-optic active control for quantum integrated photonics

    CERN Document Server

    Humphreys, Peter C; Spring, Justin B; Moore, Merritt; Salter, Patrick S; Booth, Martin J; Kolthammer, W Steven; Walmsley, Ian A

    2014-01-01

    We present a practical method for active phase control on a photonic chip that has immediate applications in quantum photonics. Our approach uses strain-optic modification of the refractive index of individual waveguides, effected by a millimeter-scale mechanical actuator. The resulting phase change of propagating optical fields is rapid and polarization-dependent, enabling quantum applications that require active control and polarization encoding. We demonstrate strain-optic control of non-classical states of light in silica, showing the generation of 2-photon polarisation N00N states by manipulating Hong-Ou-Mandel interference. We also demonstrate switching times of a few microseconds, which are sufficient for silica-based feed-forward control of photonic quantum states.

  10. Human brain activity with functional NIR optical imager

    Science.gov (United States)

    Luo, Qingming

    2001-08-01

    In this paper we reviewed the applications of functional near infrared optical imager in human brain activity. Optical imaging results of brain activity, including memory for new association, emotional thinking, mental arithmetic, pattern recognition ' where's Waldo?, occipital cortex in visual stimulation, and motor cortex in finger tapping, are demonstrated. It is shown that the NIR optical method opens up new fields of study of the human population, in adults under conditions of simulated or real stress that may have important effects upon functional performance. It makes practical and affordable for large populations the complex technology of measuring brain function. It is portable and low cost. In cognitive tasks subjects could report orally. The temporal resolution could be millisecond or less in theory. NIR method will have good prospects in exploring human brain secret.

  11. Design of an Optically Controlled MR-Compatible Active Needle

    Science.gov (United States)

    Ryu, Seok Chang; Quek, Zhan Fan; Koh, Je-Sung; Renaud, Pierre; Black, Richard J.; Moslehi, Behzad; Daniel, Bruce L.; Cho, Kyu-Jin; Cutkosky, Mark R.

    2015-01-01

    An active needle is proposed for the development of magnetic resonance imaging (MRI)-guided percutaneous procedures. The needle uses a low-transition-temperature shape memory alloy (LT SMA) wire actuator to produce bending in the distal section of the needle. Actuation is achieved with internal optical heating using laser light transported via optical fibers and side coupled to the LT SMA. A prototype, with a size equivalent to a standard 16-gauge biopsy needle, exhibits significant bending, with a tip deflection of more than 14° in air and 5° in hard tissue. A single-ended optical sensor with a gold-coated tip is developed to measure the curvature independently of temperature. The experimental results in tissue phantoms show that human tissue causes fast heat dissipation from the wire actuator; however, the active needle can compensate for typical targeting errors during prostate biopsy. PMID:26512231

  12. Novel method for high accuracy figure measurement of optical flat

    Science.gov (United States)

    E, Kewei; Li, Dahai; Yang, Lijie; Guo, Guangrao; Li, Mengyang; Wang, Xuemin; Zhang, Tao; Xiong, Zhao

    2017-01-01

    Phase Measuring Deflectometry (PMD) is a non-contact, high dynamic-range and full-field metrology which becomes a serious competitor to interferometry. However, the accuracy of deflectometry metrology is strongly influenced by the level of the calibrations, including test geometry, imaging pin-hole camera and digital display. In this paper, we propose a novel method that can measure optical flat surface figure to a high accuracy. We first calibrate the camera using a checker pattern shown on a LCD display at six different orientations, and the last orientation is aligned at the same position as the test optical flat. By using this method, lens distortions and the mapping relationship between the CCD pixels and the subaperture coordinates on the test optical flat can be determined at the same time. To further reduce the influence of the calibration errors on measurements, a reference optical flat with a high quality surface is measured, and then the system errors in our PMD setup can be eliminated by subtracting the figure of the reference flat from the figure of the test flat. Although any expensive coordinates measuring machine, such as laser tracker and coordinates measuring machine are not applied in our measurement, our experimental results of optical flat figure from low to high order aberrations still show a good agreement with that from the Fizeau interferometer.

  13. Active Optical Devices and Applications. Volume 228

    Science.gov (United States)

    1980-04-01

    array (supplied by Reticon Corporation), with center-to-center spacing of 100 ym between two adjacent photodiodes, is shown in Figure 6b. This array...survey stage to the detailed study stage of its evolution. Gamma ray measurements reveal the explosive high energy nuclear and elementary particle...provide direct evidence for the occurrence of nuclear reactions leading to element synthesis. Gamma rays produced by interactions of cosmic rays with the

  14. Optical-radio positional offsets for active galactic nuclei

    CERN Document Server

    Orosz, G

    2013-01-01

    Context. It will soon become possible to directly link the most accurate radio reference frame with the Gaia optical reference frame using many common extragalactic objects. It is important to know the level of coincidence between the radio and optical positions of compact active galactic nuclei (AGN). Aims. Using the best catalogues available at present, we investigate how many AGN with significantly large optical-radio positional offsets exist as well as the possible causes of these offsets. Methods. We performed a case study by finding optical counterparts to the International Celestial Reference Frame (ICRF2) radio sources in the Sloan Digital Sky Survey (SDSS) Data Release 9 (DR9). The ICRF2 catalogue was used as a reference because the radio positions determined by Very Long Baseline Interferometry (VLBI) observations are about two orders of magnitude more accurate than the optical positions. Results. We find 1297 objects in common for ICRF2 and SDSS DR9. Statistical analysis of the optical-radio differ...

  15. Transport of Optically Active Particles from the Surface Mixed Layer

    Science.gov (United States)

    2005-09-30

    aragonite in the form of abundant coccoliths and coccospheres, and occasional forams, pteropods and larval gastropods . The δ18O signature of the 2003... APPLICATIONS These experiments were designed to identify the major loss terms of optically-active particles. This indeed was accomplished. Such

  16. New high performance Si for optical devices

    Science.gov (United States)

    Tenma, T.; Matsuzaka, M.; Sako, R.; Takase, K.; Chiba, K.

    2016-05-01

    Against the backdrop of a growing demand in the areas of smart buildings, security, vehicle installation, and other applications, the market for far infrared cameras is expected to grow significantly in the future. However, since germanium (Ge) and chalcogenide glass, which have been used as the lens materials of far infrared cameras, are very expensive or highly toxic, there are some problems supporting the growing demand. We have therefore focused attention on silicon, which is inexpensive and less toxic. Although silicon has been used as a lens material of far infrared cameras, there are some problems remaining to be solved: Cz silicon is inexpensive but delivers low transmittance, and Fz silicon delivers sufficient transmittance but is expensive. We have developed New Cz silicon, which delivers high transmittance as Fz silicon does, and is inexpensive as conventional Cz silicon is. We have already started its sample work at both companies in Japan and overseas and have obtained excellent performance results. Mass production is scheduled to start in this fiscal year.

  17. Modeling, fabrication and high power optical characterization of plasmonic waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Lysenko, Oleg

    2015-01-01

    This paper describes modeling, fabrication and high power optical characterization of thin gold films embedded in silicon dioxide. The propagation vector of surface plasmon polaritons has been calculated by the effective index method for the wavelength range of 750-1700 nm and film thickness of 15......, 30 and 45 nm. The fabrication process of such plasmonic waveguides with width in the range of 1-100 μm and their quality inspection are described. The results of optical characterization of plasmonic waveguides using a high power laser with the peak power wavelength 1064 nm show significant deviation...

  18. High-resolution second harmonic optical coherence tomography

    Science.gov (United States)

    Jiang, Yi; Tomov, Ivan V.; Wang, Yimin; Chen, Zhongping

    2005-04-01

    A high-resolution Second Harmonic Optical Coherence Tomography (SH-OCT) system is demonstrated using a spectrum broadened femtosecond Ti:sapphire laser. An axial resolution of 4.2 μm at the second harmonic wave center wavelength of 400 nm has been achieved. Because the SH-OCT system uses the second harmonic generation signals that strongly depend on the orientation, polarization and local symmetry properties of chiral molecules, this technique provides unique contrast enhancement to conventional optical coherence tomography. The system is applied to image biological tissues like the rat-tail tendon. Images of highly organized collagen fibrils in the rat-tail tendon have been demonstrated.

  19. Optical imaging of neural and hemodynamic brain activity

    Science.gov (United States)

    Schei, Jennifer Lynn

    Optical imaging technologies can be used to record neural and hemodynamic activity. Neural activity elicits physiological changes that alter the optical tissue properties. Specifically, changes in polarized light are concomitant with neural depolarization. We measured polarization changes from an isolated lobster nerve during action potential propagation using both reflected and transmitted light. In transmission mode, polarization changes were largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. To overcome irregular cell orientation found in the brain, we measured polarization changes from a nerve tied in a knot. Our results show that neural activation produces polarization changes that can be imaged even without regular cell orientations. Neural activation expends energy resources and elicits metabolic delivery through blood vessel dilation, increasing blood flow and volume. We used spectroscopic imaging techniques combined with electrophysiological measurements to record evoked neural and hemodynamic responses from the auditory cortex of the rat. By using implantable optics, we measured responses across natural wake and sleep states, as well as responses following different amounts of sleep deprivation. During quiet sleep, evoked metabolic responses were larger compared to wake, perhaps because blood vessels were more compliant. When animals were sleep deprived, evoked hemodynamic responses were smaller following longer periods of deprivation. These results suggest that prolonged neural activity through sleep deprivation may diminish vascular compliance as indicated by the blunted vascular response. Subsequent sleep may allow vessels to relax, restoring their ability to deliver blood. These results also suggest that severe sleep deprivation or chronic

  20. Activities at Los Alamos for the optical model segment of the RIPL CRP

    Energy Technology Data Exchange (ETDEWEB)

    Young, P.G.

    1997-05-10

    This report discusses activity at Los Alamos on the nuclear optical model. In particular, the following topics are discussed: format of the optical model parameter library; contents of the library; validation of the optical model library; and conclusions and recommendations.

  1. Reliability of high power laser diodes with external optical feedback

    Science.gov (United States)

    Bonsendorf, Dennis; Schneider, Stephan; Meinschien, Jens; Tomm, Jens W.

    2016-03-01

    Direct diode laser systems gain importance in the fields of material processing and solid-state laser pumping. With increased output power, also the influence of strong optical feedback has to be considered. Uncontrolled optical feedback is known for its spectral and power fluctuation effects, as well as potential emitter damage. We found that even intended feedback by use of volume Bragg gratings (VBG) for spectral stabilization may result in emitter lifetime reduction. To provide stable and reliable laser systems design, guidelines and maximum feedback ratings have to be found. We present a model to estimate the optical feedback power coupled back into the laser diode waveguide. It includes several origins of optical feedback and wide range of optical elements. The failure thresholds of InGaAs and AlGaAs bars have been determined not only at standard operation mode but at various working points. The influence of several feedback levels to laser diode lifetime is investigated up to 4000h. The analysis of the semiconductor itself leads to a better understanding of the degradation process by defect spread. Facet microscopy, LBIC- and electroluminescence measurements deliver detailed information about semiconductor defects before and after aging tests. Laser diode protection systems can monitor optical feedback. With this improved understanding, the emergency shutdown threshold can be set low enough to ensure laser diode reliability but also high enough to provide better machine usability avoiding false alarms.

  2. Impact of optical antennas on active optoelectronic devices.

    Science.gov (United States)

    Bonakdar, Alireza; Mohseni, Hooman

    2014-10-07

    Remarkable progress has been made in the fabrication and characterization of optical antennas that are integrated with optoelectronic devices. Herein, we describe the fundamental reasons for and experimental evidence of the dramatic improvements that can be achieved by enhancing the light-matter interaction via an optical antenna in both photon-emitting and -detecting devices. In addition, integration of optical antennas with optoelectronic devices can lead to the realization of highly compact multifunctional platforms for future integrated photonics, such as low-cost lab-on-chip systems. In this review paper, we further focus on the effect of optical antennas on the detectivity of infrared photodetectors. One particular finding is that the antenna can have a dual effect on the specific detectivity, while it can elevate light absorption efficiency of sub-wavelength detectors, it can potentially increase the noise of the detectors due to the enhanced spontaneous emission rate. In particular, we predict that the detectivity of interband photon detectors can be negatively affected by the presence of optical antennas across a wide wavelength region covering visible to long wavelength infrared bands. In contrast, the detectivity of intersubband detectors could be generally improved with a properly designed optical antenna.

  3. Optics of High-Energy Beams

    Energy Technology Data Exchange (ETDEWEB)

    Chamberlain, Owen

    1960-05-01

    Many of the experiments now being conducted on high-energy accelerators requires the use of beams of charged secondary particles. It is worth while at this time to attempt to summarize information about some of the most useful methods of setting up such beams. We are not concerned here with the primary beam of the accelerator. Rather, they assume that a target is struck by the primary beam and that it is desired to form a beam from the secondary charged particles that emerge from collisions within the target. The simplest system of forming this beam of secondary particles involves the use of magnetic fields only. In most cases it is desirable to obtain a beam of particles of known magnetic rigidity, or momentum. The bulk of this article is addressed to this problem. Some comments are also made about the use of electric fields in conjunction with magnetic fields. The inclusion of electric fields allows the separation of a beam of known momentum into its various components according to the velocities of the particles, hence according to the masses of the particles. These are referred to as ''separated beams''.

  4. High efficiency coherent beam combining of semiconductor optical amplifiers.

    Science.gov (United States)

    Creedon, Kevin J; Redmond, Shawn M; Smith, Gary M; Missaggia, Leo J; Connors, Michael K; Kansky, Jan E; Fan, Tso Yee; Turner, George W; Sanchez-Rubio, Antonio

    2012-12-01

    We demonstrate 40 W coherently combined output power in a single diffraction-limited beam from a one-dimensional 47-element array of angled-facet slab-coupled optical waveguide amplifiers at 1064 nm. The output from each emitter was collimated and overlapped onto a diffractive optical element combiner using a common transform lens. Phase locking was achieved via active feedback on each amplifier's drive current to maximize the power in the combined beam. The combining efficiency at all current levels was nearly constant at 87%.

  5. High-fidelity angle-modulated analog optical link.

    Science.gov (United States)

    Che, Di; Yuan, Feng; Shieh, William

    2016-07-25

    There has long existed a debate over whether analog or digital optical link is more suitable for wireless convergence applications. Digital link achieves the highest fidelity, with the sacrifice of huge bandwidth due to the high resolution of digitization, and large power consumption due to the exhaustive digital data recovery. Analog link avoids these drawbacks, but it inevitably suffers from the SNR degradation. In this paper, we propose the angle modulation for analog optical link, which successfully breaks the SNR ceiling of amplitude modulation, and achieves ultrahigh link fidelity. Using the digital link (CPRI) equivalent bandwidth, angle modulation exhibits around 30-dB SNR advantage over the conventional amplitude modulation. Combined with its high tolerance on link nonlinearity, angle modulation has great potential in the future SNR-hungry analog optical applications.

  6. A novel optical burst switching architecture for high speed networks

    Institute of Scientific and Technical Information of China (English)

    Amit Kumar Garg; R. S. Kaler

    2008-01-01

    A novel optical burst switching (OBS) high speed network architecture has been proposed. To verify its feasibility and evaluate its performance, just-enough-time (JET) signaling has been considered as a high performance protocol. In the proposed architecture, to avoid burst losses, firstly, a short-priorconfirrnation-packet (SPCP) is sent over the control channel that simulates the events that the actual packet will experience. Once SPCP detects a drop at any of the intermediate nodes, the actual packet is not sent but the process repeats. In order to increase network utilization, cost effectiveness and to overcome some limitations of conventional OBS, inherent codes (e.g., orthogonal optical codes (OOC)),which are codified only in intensity, has been used. Through simulations, it shows that a decrease in burst loss probability, cost effectiveness and a gain in processing time are obtained when optical label processing is used as compared with electronic processing.

  7. Pattern matching based active optical sorting of colloids/cells

    Science.gov (United States)

    Verma, R. S.; Dasgupta, R.; Ahlawat, S.; Kumar, N.; Uppal, A.; Gupta, P. K.

    2013-08-01

    We report active optical sorting of colloids/cells by employing a cross correlation based pattern matching technique for selection of the desired objects and thereafter sorting using dynamically controllable holographic optical traps. The problem of possible collision between the different sets of objects during sorting was avoided by raising one set of particles to a different plane. We also present the results obtained on using this approach for some representative applications such as sorting of silica particles of two different sizes, of closely packed colloids and of white blood cells and red blood cells from a mixture of the two.

  8. Kepler Observations of Rapid Optical Variability in Active Galactic Nuclei

    CERN Document Server

    Mushotzky, Richard F; Baumgartner, Wayne H; Gandhi, Poshak

    2011-01-01

    Over three quarters in 2010-2011, Kepler monitored optical emission from four active galactic nuclei (AGN) with ~30 min sampling, >90% duty cycle, and <~0.1% repeatability. These data determined the AGN optical fluctuation power spectral density functions (PSDs) over a wide range in temporal frequency. Fits to these PSDs yielded power law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGN exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN variability models but seem consistent with first order MRI theoretical calculations of accretion disk fluctuations.

  9. Comparison of different technologies for high-quality optical coatings

    Science.gov (United States)

    Flory, Francois

    1990-08-01

    Modern optical systems require still higher quality optical coatings. Conventional production techniques are not able to give such high quality layers. One of the main defaults comes from the relatively porous structure of the thin films; as a consequence the sensitiveness of the materials to the moisture gives noticeably unstable properties versus time. In this work, after a very short review of the different techniques nowaday used to perform high quality optical thin films, we will be especially interested in oxide layer production (Si02, Ta2O5, Ti02). To give a good comparison of the performances obtained with techniques such as TAD and ion plating we need extremely powerful characterization means: - In vacuo measurements of optical properties allowing the study of spontaneous water adsorption during air entrance; - Absorption measurement with photothermal deflection spectroscopy; - Scattering losses measurements and consequently determination of the grain size of the microstructure. Refractive index measurements, and optical anisotropy determined by guided mode study. Finally some views from electron microscopy justify the validity of the model used with our characterization techniques. To end, we will show the interest of ion plating technique when we are looking for very uniform deposition on large surfaces.

  10. Optical packaging activities at Institute of Microelectronics (IME), Singapore

    Science.gov (United States)

    Teo, Keng-Hwa; Sudharsanam, Krishnamachari; Pamidighantam, Ramana V.; Yeo, Yongkee; Iyer, Mahadevan K.

    2002-08-01

    The development of optoelectronic components for gigabit Ethernet communications is converging towards access networks where the cost of device makes a significant impact on the market acceptance. Device fabrication and packaging cost have to be brought down with novel assembly and packaging methods. Singapore has established a reputation in semiconductor device development and fabrication with excellent process and packaging facilities. Institute of Microelectronics (IME) was founded in 1991 to add value to the Singapore electronics industry. IME is involved in the development of active and passive photonics components using Silicon and polymer materials. We present a brief report on the development activities taking place in the field of optical component packaging at IME in recent years. We present a review of our competence and some of the optical device packaging activities that are being undertaken.

  11. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    Science.gov (United States)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  12. New insight into the solution structures of wheat gluten proteins from Raman optical activity

    DEFF Research Database (Denmark)

    Blanch, E.W.; Kasarda, D.D.; Hecht, L.

    2003-01-01

    Vibrational Raman optical activity (ROA) spectra of the wheat proteins a-gliadin (A-gliadin), omega-liadin, and a 30 kDa peptide called T-A-1 from the high molecular weight glutenin subunit (HMW-GS) Dx5 were measured to obtain new information about their solution structures. The spectral data sho...

  13. New insight into the solution structures of wheat gluten proteins from Raman optical activity

    DEFF Research Database (Denmark)

    Blanch, E.W.; Kasarda, D.D.; Hecht, L.

    2003-01-01

    Vibrational Raman optical activity (ROA) spectra of the wheat proteins a-gliadin (A-gliadin), omega-liadin, and a 30 kDa peptide called T-A-1 from the high molecular weight glutenin subunit (HMW-GS) Dx5 were measured to obtain new information about their solution structures. The spectral data sho...

  14. Optical Illusions: A Presentation for High School Mathematics Students.

    Science.gov (United States)

    Brandes, Louis Grant

    1983-01-01

    Optical illusions are assumed to be of interest to high school mathematics students. The article indicates how a topic can be both educational and entertaining. Readers are invited to try to construct some illusions on their own, and to see if they can classify them. (MP)

  15. Modeling, fabrication and high power optical characterization of plasmonic waveguides

    DEFF Research Database (Denmark)

    Lavrinenko, Andrei; Lysenko, Oleg

    2015-01-01

    This paper describes modeling, fabrication and high power optical characterization of thin gold films embedded in silicon dioxide. The propagation vector of surface plasmon polaritons has been calculated by the effective index method for the wavelength range of 750-1700 nm and film thickness of 1...

  16. Bio-optofluidics and Bio-photonics: Programmable Phase Optics activities at DTU Fotonik

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Palima, Darwin; Pedersen, Finn

    We present ongoing research and development activities for constructing a compact next generation BioPhotonics Workstation and a Bio-optofluidic Cell Sorter (cell-BOCS) for all-optical micromanipulation platforms utilizing low numerical aperture beam geometries. Unlike conventional high NA optica...... the BioPhotonics Workstation platform more photon efficient by studying the 3D distribution of the counter propagating beams and utilizing the Generalized Phase Contrast (GPC) method for illuminating the applied spatial light modulators.......We present ongoing research and development activities for constructing a compact next generation BioPhotonics Workstation and a Bio-optofluidic Cell Sorter (cell-BOCS) for all-optical micromanipulation platforms utilizing low numerical aperture beam geometries. Unlike conventional high NA optical...

  17. Development of fluorides for high power laser optics

    Energy Technology Data Exchange (ETDEWEB)

    Ready, J.F.; Vora, H.

    1980-07-01

    The laser-assisted thermonuclear fusion program has significant needs for improved optical materials with high transmission in the ultraviolet, and with low values of nonlinear index of refraction. Lithium fluoride (LiF) possesses a combination of optical properties which are of potential use. Single-crystalline LiF is limited by low mechanical strength. In this program, we investigated the technique of press-forging to increase the mechanical strength. LiF single crystals were press-forged over the temperature range 300 to 600/sup 0/C to produce fine-grained polycrystalline material.

  18. Gigahertz planar photoconducting antenna activated by picosecond optical pulses.

    Science.gov (United States)

    Liu, D W; Thaxter, J B; Bliss, D F

    1995-07-15

    We have generated 1-20-GHz microwave pulses by illuminating an Fe-compensated InP wafer with 50-ps optical pulses at normal incidence. The process of the generation of microwave radiation was monitored and analyzed directly through a 40-GHz sampling oscilloscope with precision. The saturation properties, the waveform evolution, and the optical coupling efficiency of the gigahertz photoconducting antenna are discussed. The flexibility, compactness, and high-resolution features offered by this technique merit new applications for radar communication as well as for other microwave detecting devices.

  19. High-Resolution Mammography Detector Employing Optical Switching Readout

    Science.gov (United States)

    Irisawa, Kaku; Kaneko, Yasuhisa; Yamane, Katsutoshi; Sendai, Tomonari; Hosoi, Yuichi

    Conceiving a new detector structure, FUJIFILM Corporation has successfully put its invention of an X-ray detector employing "Optical Switching" into practical use. Since Optical Switching Technology allows an electrode structure to be easily designed, both high resolution of pixel pitch and low electrical noise readout have been achieved, which have consequently realized the world's smallest pixel size of 50×50 μm2 from a Direct-conversion FPD system as well as high DQE. The digital mammography system equipped with this detector enables to acquire high definition images while maintaining granularity. Its outstanding feature is to be able to acquire high-precision images of microcalcifications which is an important index in breast examination.

  20. Towards optical intensity interferometry for high angular resolution stellar astrophysics

    CERN Document Server

    Nunez, Paul D

    2012-01-01

    Most neighboring stars are still detected as point sources and are beyond the angular resolution reach of current observatories. Methods to improve our understanding of stars at high angular resolution are investigated. Air Cherenkov telescopes (ACTs), primarily used for Gamma-ray astronomy, enable us to increase our understanding of the circumstellar environment of a particular system. When used as optical intensity interferometers, future ACT arrays will allow us to detect stars as extended objects and image their surfaces at high angular resolution. Optical stellar intensity interferometry (SII) with ACT arrays, composed of nearly 100 telescopes, will provide means to measure fundamental stellar parameters and also open the possibility of model-independent imaging. A data analysis algorithm is developed and permits the reconstruction of high angular resolution images from simulated SII data. The capabilities and limitations of future ACT arrays used for high angular resolution imaging are investigated via ...

  1. Compact silica-on-silicon planar lightwave circuits for high speed optical signal processing

    Science.gov (United States)

    Callender, C. L.; Dumais, P.; Blanchetiere, C.; Jacob, S.; Ledderhof, C.; Smelser, C. W.; Yadav, K.; Albert, J.

    2012-02-01

    Silica-on-silicon planar lightwave circuit (PLC) technology is well established and provides a low loss and stable photonic device platform. However, limitations in size and integration of active components remain. Engineering of the layer structure in silica PLCs to achieve high-index contrast, compact device architectures and monolithically integrated optical nonlinearities is described. Modeling of properties of doped-silica layers provides a design strategy for optimization of waveguide loss and birefringence. Optical nonlinearities in poled silica layers have been demonstrated, and recent work to incorporate these into functional device structures and exploit them for high speed modulation is reported.

  2. High throughput optoelectronic smart pixel systems using diffractive optics

    Science.gov (United States)

    Chen, Chih-Hao

    1999-12-01

    Recent developments in digital video, multimedia technology and data networks have greatly increased the demand for high bandwidth communication channels and high throughput data processing. Electronics is particularly suited for switching, amplification and logic functions, while optics is more suitable for interconnections and communications with lower energy and crosstalk. In this research, we present the design, testing, integration and demonstration of several optoelectronic smart pixel devices and system architectures. These systems integrate electronic switching/processing capability with parallel optical interconnections to provide high throughput network communication and pipeline data processing. The Smart Pixel Array Cellular Logic processor (SPARCL) is designed in 0.8 m m CMOS and hybrid integrated with Multiple-Quantum-Well (MQW) devices for pipeline image processing. The Smart Pixel Network Interface (SAPIENT) is designed in 0.6 m m GaAs and monolithically integrated with LEDs to implement a highly parallel optical interconnection network. The Translucent Smart Pixel Array (TRANSPAR) design is implemented in two different versions. The first version, TRANSPAR-MQW, is designed in 0.5 m m CMOS and flip-chip integrated with MQW devices to provide 2-D pipeline processing and translucent networking using the Carrier- Sense-MultipleAccess/Collision-Detection (CSMA/CD) protocol. The other version, TRANSPAR-VM, is designed in 1.2 m m CMOS and discretely integrated with VCSEL-MSM (Vertical-Cavity-Surface- Emitting-Laser and Metal-Semiconductor-Metal detectors) chips and driver/receiver chips on a printed circuit board. The TRANSPAR-VM provides an option of using the token ring network protocol in addition to the embedded functions of TRANSPAR-MQW. These optoelectronic smart pixel systems also require micro-optics devices to provide high resolution, high quality optical interconnections and external source arrays. In this research, we describe an innovative

  3. Optical studies of high-temperature superconducting cuprates

    Science.gov (United States)

    Tajima, Setsuko

    2016-09-01

    The optical studies of high-temperature superconducting cuprates (HTSC) are reviewed. From the doping dependence of room temperature spectra, a dramatic change of the electronic state from a Mott (charge transfer) insulator to a Fermi liquid has been revealed. Additionally, the unusual 2D nature of the electronic state has been found. The temperature dependence of the optical spectra provided a rich source of information on the pseudogap, superconducting gap, Josephson plasmon, transverse Josephson plasma mode and precursory superconductivity. Among these issues, Josephson plasmons and transverse Josephson plasma mode were experimentally discovered by optical measurements, and thus are unique to HTSC. The effect of the spin/charge stripe order is also unique to HTSC, reflecting the conducting nature of the stripe order in this system. The pair-breaking due to the stripe order seems stronger in the out-of-plane direction than in the in-plane one.

  4. Propagation of Optical Pulses in Polarization Maintaining Highly Birefringent Fibers

    Science.gov (United States)

    Leiva, Ariel; Olivares, Ricardo

    2008-04-01

    The propagation of Gaussian optical pulses through optical PM-HiBi (Polarization Maintaining Highly Birefringent) fibers is analyzed and simulated. Based upon a model of propagation as described by Marcuse, et al., [1] and Sunnerud, et al., [2], and the use of PMD (Polarization Mode Dispersion) compensators and emulators used by Kogelnik, et al. [2], [3] and Lima, et al. [4], we construct a simple model that allows graphical representation of the distortion experienced by optical pulses when propagating in a PM-HiBi fiber for different initial polarizations. The results of our analysis have the benefit of being identical to the more elaborate models of [1], [2], while also providing the additional advantage of simple graphical representation.

  5. Bendable X-ray Optics for High Resolution Imaging

    Science.gov (United States)

    Gubarev, M.; Ramsey, B.; Kilaru, K.; Atkins, C.; Broadway, D.

    2014-01-01

    Current state-of the-art for x-ray optics fabrication calls for either the polishing of massive substrates into high-angular-resolution mirrors or the replication of thin, lower-resolution, mirrors from perfectly figured mandrels. Future X-ray Missions will require a change in this optics fabrication paradigm in order to achieve sub-arcsecond resolution in light-weight optics. One possible approach to this is to start with perfectly flat, light-weight surface, bend it into a perfect cone, form the desired mirror figure by material deposition, and insert the resulting mirror into a telescope structure. Such an approach is currently being investigated at MSFC, and a status report will be presented detailing the results of finite element analyses, bending tests and differential deposition experiments.

  6. Ultra-high-speed serial optical communications: Enabling technologies

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2008-01-01

    This paper will present recently identified and demonstrated key technologies for ultra-high-speed serial communications. Certain key components such as stabilised highly non-linear fibre switches, periodically poled Lithium Niobate devices and semiconductor optical amplifiers will be described...... with demonstrations of 640 Gb/s transmission, clock recovery, demultiplexing, add/drop, wavelength conversion and channel identification. Timing jitter tolerance is addressed through techniques to create flat-top pulses....

  7. Fluctuating nanomechanical systems in a high finesse optical microcavity

    CERN Document Server

    Favero, I; Hunger, D; Paulitschke, P; Reichel, J; Lorenz, H; Weig, E M; Karrai, K

    2009-01-01

    Confining a laser field between two high reflectivity mirrors of a high-finesse cavity can increase the probability of a given cavity photon to be scattered by an atom traversing the confined photon mode. This enhanced coupling between light and atoms is successfully employed in cavity quantum electrodynamics experiments and led to a very prolific research in quantum optics. The idea of extending such experiments to sub-wavelength sized nanomechanical systems has been recently proposed in the context of optical cavity cooling. Here we present an experiment involving a single nanorod consisting of about 10^9 atoms precisely positioned to plunge into the confined mode of a miniature high finesse Fabry-Perot cavity. We show that the optical transmission of the cavity is affected not only by the static position of the nanorod but also by its vibrational fluctuation. While an imprint of the vibration dynamics is directly detected in the optical transmission, back-action of the light field is also anticipated to qu...

  8. Optical micromachined ultrasound transducers (OMUT) - a new approach for high resolution imaging

    Science.gov (United States)

    Tadayon, M. A.; Ashkenazi, S.

    2013-03-01

    Piezoelectric ultrasound (US) transducers are at the heart of almost any ultrasonic medical imaging probe. However, their sensitivity and reliability severely degrade in applications requiring high frequency (>20 MHz) and small element size (construct micron-size air cavities capped by an elastic membrane. The membrane functions as the active ultrasound transmitter and receiver. We will describe the design and testing of prototype OMUT devices which implement a receive-only function. The cavity detector is an optical cavity which its top mirror is deflected under the application of pressure. The intensity of a reflected light beam is highly sensitive to displacement of the top membrane if the optical wavelength is at near-resonance condition. Therefore, US pulses can be detected by recording the reflected light intensity. The sensitivity of the device depends on the mechanical properties of the top membrane and optical characteristics of the optical cavity. The device was fabricated using SU8 as a structural material and gold as a mirror. We have developed a new bonding method to fabricate a sealed, low roughness, high quality optical cavity. The 60μm cavity with the 8.5 μm top membrane is tested in water with 25MHz ultrasound transducer. The NEP of the device for bandwidth of 28MHz was 9.25kPa. The optical cavity has a finesse of around 23.

  9. Coherent DWDM technology for high speed optical communications

    Science.gov (United States)

    Saunders, Ross

    2011-10-01

    The introduction of coherent digital optical transmission enables a new generation of high speed optical data transport and fiber impairment mitigation. An initial implementation of 40 Gb/s coherent systems using Dual Polarization Quadrature Phase Shift Keying (DP-QPSK) is already being installed in carrier networks. New systems running at 100 Gb/s DP-QPSK data rate are in development and early technology lab and field trial phase. Significant investment in the 100 Gb/s ecosystem (optical components, ASICs, transponders and systems) bodes well for commercial application in 2012 and beyond. Following in the footsteps of other telecommunications fields such as wireless and DSL, we can expect coherent optical transmission to evolve from QPSK to higher order modulations schemes such as Mary PSK and/or QAM. This will be an interesting area of research in coming years and poses significant challenges in terms of electro-optic, DSP, ADC/DAC design and fiber nonlinearity mitigation to reach practical implementation ready for real network deployments.

  10. High-resolution optical tweezers for single-molecule manipulation.

    Science.gov (United States)

    Zhang, Xinming; Ma, Lu; Zhang, Yongli

    2013-09-01

    Forces hold everything together and determine its structure and dynamics. In particular, tiny forces of 1-100 piconewtons govern the structures and dynamics of biomacromolecules. These forces enable folding, assembly, conformational fluctuations, or directional movements of biomacromolecules over sub-nanometer to micron distances. Optical tweezers have become a revolutionary tool to probe the forces, structures, and dynamics associated with biomacromolecules at a single-molecule level with unprecedented resolution. In this review, we introduce the basic principles of optical tweezers and their latest applications in studies of protein folding and molecular motors. We describe the folding dynamics of two strong coiled coil proteins, the GCN4-derived protein pIL and the SNARE complex. Both complexes show multiple folding intermediates and pathways. ATP-dependent chromatin remodeling complexes translocate DNA to remodel chromatin structures. The detailed DNA translocation properties of such molecular motors have recently been characterized by optical tweezers, which are reviewed here. Finally, several future developments and applications of optical tweezers are discussed. These past and future applications demonstrate the unique advantages of high-resolution optical tweezers in quantitatively characterizing complex multi-scale dynamics of biomacromolecules.

  11. Design method for automotive high-beam LED optics

    Science.gov (United States)

    Byzov, Egor V.; Moiseev, Mikhail A.; Doskolovich, Leonid L.; Kazanskiy, Nikolay L.

    2015-09-01

    New analytical method for the calculation of the LED secondary optics for automotive high-beam lamps is presented. Automotive headlamps should illuminate the road and the curb at the distance of 100-150 meters and create a bright, flat, relatively powerful light beam. To generate intensity distribution of this kind we propose to use TIR optical element (collimator working on the total internal reflection principle) with array of microlenses (optical corrector) on the upper surface. TIR part of the optical element enables reflection of the side rays to the front direction and provides a collimated beam which incidents on the microrelief. Microrelief, in its turn, dissipates the light flux in horizontal direction to meet the requirements of the Regulations 112, 113 and to provide well-illuminated area across the road in the far field. As an example, we computed and simulated the optical element with the diameter of 33 millimeters and the height of 22 millimeters. Simulation data shows that three illuminating modules including Cree XP-G2 LED and lens allow generating an appropriate intensity distribution for the class D of UNECE Regulations.

  12. Integrated optical gyroscope using active long-range surface plasmon-polariton waveguide resonator.

    Science.gov (United States)

    Zhang, Tong; Qian, Guang; Wang, Yang-Yang; Xue, Xiao-Jun; Shan, Feng; Li, Ruo-Zhou; Wu, Jing-Yuan; Zhang, Xiao-Yang

    2014-01-24

    Optical gyroscopes with high sensitivity are important rotation sensors for inertial navigation systems. Here, we present the concept of integrated resonant optical gyroscope constructed by active long-range surface plasmon-polariton (LRSPP) waveguide resonator. In this gyroscope, LRSPP waveguide doped gain medium is pumped to compensate the propagation loss, which has lower pump noise than that of conventional optical waveguide. Peculiar properties of single-polarization of LRSPP waveguide have been found to significantly reduce the polarization error. The metal layer of LRSPP waveguide is electro-optical multiplexed for suppression of reciprocal noises. It shows a limited sensitivity of ~10(-4) deg/h, and a maximum zero drift which is 4 orders of magnitude lower than that constructed by conventional single-mode waveguide.

  13. Estuarine morphometry governs optically active substances, Kd(PAR) and beam attenuation

    DEFF Research Database (Denmark)

    Lund-Hansen, L. C.; Nielsen, J. M.; Blüthgen, J.

    2013-01-01

    Data on optical properties such as diffuse attenuation coefficient Kd(PAR), beam attenuation coefficient (cp) and the optically active constituents (OACs) CDOM, Chl-a and suspended particulate matter were obtained in a Danish temperate coastal plain estuary (56°N) and a Vietnamese tropical ria (12......°N) at high discharges. The major difference was the spatial distribution of the optical properties against distance, best described by significant power functions in the ria, compared to significant linear functions in the coastal plain. It was hypothesized that estuarine morphometry could explain...... estuaries using OACs as input parameters. It is concluded that there are no large differences in OAC concentrations between the two estuaries. The spatial distributions of OACs and optical properties were significantly different and governed by the estuary morphometry, i.e. a power distribution...

  14. High numerical aperture imaging by using multimode fibers with micro-fabricated optics

    KAUST Repository

    Bianchi, Silvio

    2014-01-01

    Controlling light propagation into multimode optical fibers through spatial light modulators provides highly miniaturized endoscopes and optical micromanipulation probes. We increase the numerical aperture up to nearly 1 by micro-optics fabricated on the fiber-end.

  15. High magneto-optical characteristics of Holmium-doped terbium gallium garnet crystal.

    Science.gov (United States)

    Chen, Zhe; Yang, Lei; Wang, Xiangyong; Yin, Hang

    2016-06-01

    Magneto-optical characteristics of a new magneto-active material, (Tb(1-x)Hox)3Ga5O12 crystal, have been grown by the Czochralski (Cz) method. A high value of the Verdet constant was obtained at room temperature-namely, 214.9 and 77.8  rad·m-1 T-1 for 632.8 and 1064 nm, respectively. The Verdet constant of the Ho-doped terbium gallium garnet crystal at 1064 nm is about 2 times higher than that of terbium gallium garnet crystal. High value of magneto-optical figure-of-merit makes it an attractive next-generation magneto-optics material for high-power Faraday isolators.

  16. Physical Properties and Behaviour of Highly Bi-Substituted Magneto-Optic Garnets for Applications in Integrated Optics and Photonics

    Directory of Open Access Journals (Sweden)

    Mohammad Nur-E-Alam

    2011-01-01

    Full Text Available Rare-earth and Bi-substituted iron garnet thin film materials exhibit strong potential for application in various fields of science and frontier optical technologies. Bi-substituted iron garnets possess extraordinary optical and MO properties and are still considered as the best MO functional materials for various emerging integrated optics and photonics applications. However, these MO garnet materials are rarely seen in practical photonics use due to their high optical losses in the visible spectral region. In this paper, we report on the physical properties and magneto-optic behaviour of high-performance RF sputtered highly bismuth-substituted iron garnet and garnet-oxide nanocomposite films of generic composition type (Bi, Dy/Lu3(Fe, Ga/Al5O12. Our newly synthesized garnet materials form high-quality nanocrystalline thin film layers which demonstrate excellent optical and MO properties suitable for a wide range of applications in integrated optics and photonics.

  17. Laser-heating-based active optics for synchrotron radiation applications

    CERN Document Server

    Yang, Fugui; Zhang, Xiaowei

    2016-01-01

    Active optics has attracted considerable interest from researchers in synchrotron radiation facilities, because of its capacity for x-ray wavefront correction. Here, we report a novel and efficient technique for correcting or modulating a mirror surface profile based on laser-heating-induced thermal expansion. An experimental study of the characteristics of the surface thermal deformation response indicates that the power of a milliwatt laser yields a bump height as low as sub-nanometer scale, and that variation of the spot size modulates the response function width effectively. In addition, the capacity of the laser-heating technique for free-form surface modulation is demonstrated via a surface correction experiment. The developed method is a promising new approach towards effective x-ray active optics coupled with at-wavelength metrology techniques.

  18. Diamagnetic Raman Optical Activity of Chlorine, Bromine, and Iodine Gases.

    Science.gov (United States)

    Šebestík, Jaroslav; Kapitán, Josef; Pačes, Ondřej; Bouř, Petr

    2016-03-01

    Magnetic Raman optical activity of gases provides unique information about their electric and magnetic properties. Magnetic Raman optical activity has recently been observed in a paramagnetic gas (Angew. Chem. Int. Ed. 2012, 51, 11058; Angew. Chem. 2012, 124, 11220). In diamagnetic molecules, it has been considered too weak to be measurable. However, in chlorine, bromine and iodine vapors, we could detect a significant signal as well. Zeeman splitting of electronic ground-state energy levels cannot rationalize the observed circular intensity difference (CID) values of about 10(-4). These are explicable by participation of paramagnetic excited electronic states. Then a simple model including one electronic excited state provides reasonable spectral intensities. The results suggest that this kind of scattering by diamagnetic molecules is a general event observable under resonance conditions. The phenomenon sheds new light on the role of excited states in the Raman scattering, and may be used to probe molecular geometry and electronic structure.

  19. All-Optical Ultra-High-Speed OFDM to Nyquist-WDM Conversion Based on Complete Optical Fourier Transformation

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Mulvad, Hans Christian Hansen

    2016-01-01

    We propose a novel all-optical ultra-high-speed orthogonal frequency-division multiplexing (OFDM) to Nyquist wavelength-division multiplexing (Nyquist-WDM) conversion scheme, achieved by exchanging the temporal and spectral profiles using a complete optical Fourier transformation (OFT). This scheme...... enables high-speed OFDM to Nyquist-WDM conversion without complex optical/electrical/optical conversion. The all-optical OFDM transmitter is based on the generation of OFDM symbols with a low duty cycle by rectangular temporal gating, which in combination with optical time-division multiplexing yields...... a higher symbol-rate OFDM signal. In the receiver, the converted Nyquist-WDM super-channel is WDM demultiplexed into individual Nyquist-WDM channels using a rectangular optical bandpass filter, followed by optical sampling at the intersymbol-interference free point. In the experimental demonstration...

  20. High-irradiance reactors with unfolded aplanatic optics.

    Science.gov (United States)

    Feuermann, Daniel; Gordon, Jeffrey M

    2008-11-01

    Reconstituting the intense irradiance of short-arc discharge lamps at a remote target, at high radiative efficiency, represents a central challenge in the design of high-temperature chemical reactors, heightened by the need for high numerical aperture at both the target and the source. Separating the optical system from both the source and the reactor allows pragmatic operation, monitoring, and control. We explore near-field unfolded aplanats as feasible solutions and report measurements for a prototype that constitutes a double-ellipsoid mirror. We also propose compound unfolded aplanats that collect lamp emission over all angles (in lieu of light recycling optics) and irradiate the reactor over nearly its full circumference.

  1. Compact and high-resolution optical orbital angular momentum sorter

    Directory of Open Access Journals (Sweden)

    Chenhao Wan

    2017-03-01

    Full Text Available A compact and high-resolution optical orbital angular momentum (OAM sorter is proposed and demonstrated. The sorter comprises a quadratic fan-out mapper and a dual-phase corrector positioned in the pupil plane and the Fourier plane, respectively. The optical system is greatly simplified compared to previous demonstrations of OAM sorting, and the performance in resolution and efficiency is maintained. A folded configuration is set up using a single reflective spatial light modulator (SLM to demonstrate the validity of the scheme. The two phase elements are implemented on the left and right halves of the SLM and connected by a right-angle prism. Experimental results demonstrate the high resolution of the compact OAM sorter, and the current limit in efficiency can be overcome by replacing with transmissive SLMs and removing the beam splitters. This novel scheme paves the way for the miniaturization and integration of high-resolution OAM sorters.

  2. Activities report of the Division of Optical Technology (FOA 33)

    Science.gov (United States)

    Letalick, Dietmar

    1988-11-01

    Research on hydro-optics; laser remote sensing; coherent CO2 laser radar; optical signatures; atmospheric transmission; ionizing radiation effects on electronics; fiber optics; optical processing; and terrain models is summarized.

  3. Synthesis of Optically Active Polystyrene Catalyzed by Monophosphine Pd Complexes.

    Science.gov (United States)

    Jouffroy, Matthieu; Armspach, Dominique; Matt, Dominique; Osakada, Kohtaro; Takeuchi, Daisuke

    2016-07-11

    Cationic Pd(II) monophosphine complexes derived from α- and β-cyclodextrins (CDs) promote the homopolymerization of styrene under carbon monoxide pressure. Although reversible CO coordination takes place under catalytic conditions according to (13) C NMR studies with (13) C-enriched CO, both complexes catalyze the formation of CO-free styrene polymers. These macromolecules display optical activity as a result of the presence of stereoregular sequences within the overall atactic polymer.

  4. High-Activity Dealloyed Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Kongkanand, Anusorn [General Motors LLC, Pontiac, MI (United States)

    2014-09-30

    Reduction of costly Pt usage in proton exchange membrane fuel cell electrodes is one of the major challenges towards development and commercialization of fuel cell vehicles. Although few have met the initial-kinetic activity requirements in a realistic fuel cell device, no catalyst material has ever met the demanding fuel cell durability targets set by DOE. In this project, a team of 4 universities and 2 companies came together to investigate a concept that appeared promising in preliminary non-fuel cell tests then to further develop the catalyst to a mature level ready for vehicle implementation. The team consists of academia with technical leadership in their respective areas, a catalyst supplier, and a fuel cell system integrator.The tightly collaborative project enabled development of a highly active and durable catalyst with performance that significantly exceeds that of previous catalysts and meets the DOE targets for the first time (Figure 1A). The catalyst was then further evaluated in full-active-area stack in a realistic vehicle operating condition (Figure 1B). This is the first public demonstration that one can realize the performance benefit and Pt cost reduction over a conventional pure Pt catalyst in a long-term realistic PEMFC system. Furthermore, systematic analyses of a range of catalysts with different performance after fuel cell testing allowed for correlation between catalyst microstructure and its electrocatalytic activity and durability. This will in turn aid future catalyst development.

  5. High performance fiber-based optical coherent detection

    Science.gov (United States)

    Chen, Youming

    The sensitivity of signal detection is of major interest for optical high speed communication systems and LIght Detection And Ranging (lidar) systems. Sensitive receivers in fiber-optical networks can reduce transmitter power or amplifier amplification requirements and extend link spans. High receiver sensitivity allows links to be established over long distances in deep space satellite communication systems and large atmospheric attenuation to be overcome in terrestrial free space communications. For lidar systems, the sensitivity of signal detection determines how far and how accurately the lidar can detect the remote objects. Optical receivers employ either coherent or direct detection. In addition to amplitude, coherent detection extracts frequency and phase information from received signals, whereas direct detection extracts the received pulse amplitude only. In theory, coherent detection should yield the highest receiver sensitivity. Another possible technique to improve detection sensitivity is to employ a fiber preamplifier. This technique has been successfully demonstrated in direct detection systems but not in the coherent detection systems. Due to the existence of amplified spontaneous emission (ASE) inside the amplifier, the sensitivity of coherent detection varies with the data rate or pulse rate. For this reason, optically preamplified coherent detection is not used in applications as commonly as optically preamplified direct detection. We investigate the performance of coherent detection employing a fiber amplifier and time-domain-filter. The fiber amplifier is used as the optical preamplifier of the coherent detection system. To reduce the noise induced by the preamplifier to a maximum extent, we investigate the noise properties for both a single pass amplifier and a double pass amplifier. The relative intensity noise and linewidth broadening caused by ASE have been experimentally characterized. The results show that the double pass amplifier has

  6. High precision optical finishing of lightweight silicon carbide aspheric mirror

    Science.gov (United States)

    Kong, John; Young, Kevin

    2010-10-01

    Critical to the deployment of large surveillance optics into the space environment is the generation of high quality optics. Traditionally, aluminum, glass and beryllium have been used; however, silicon carbide becomes of increasing interest and availability due to its high strength. With the hardness of silicon carbide being similar to diamond, traditional polishing methods suffer from slow material removal rates, difficulty in achieving the desired figure and inherent risk of causing catastrophic damage to the lightweight structure. Rather than increasing structural capacity and mass of the substrate, our proprietary sub-aperture aspheric surface forming technology offers higher material removal rates (comparable to that of Zerodur or Fused Silica), a deterministic approach to achieving the desired figure while minimizing contact area and the resulting load on the optical structure. The technology performed on computer-controlled machines with motion control software providing precise and quick convergence of surface figure, as demonstrated by optically finishing lightweight silicon carbide aspheres. At the same time, it also offers the advantage of ideal pitch finish of low surface micro-roughness and low mid-spatial frequency error. This method provides a solution applicable to all common silicon carbide substrate materials, including substrates with CVD silicon carbide cladding, offered by major silicon carbide material suppliers. This paper discusses a demonstration mirror we polished using this novel technology. The mirror is a lightweight silicon carbide substrate with CVD silicon carbide cladding. It is a convex hyperbolic secondary mirror with 104mm diameter and approximately 20 microns aspheric departure from best-fit sphere. The mirror has been finished with surface irregularity of better than 1/50 wave RMS @632.8 nm and surface micro-roughness of under 2 angstroms RMS. The technology has the potential to be scaled up for manufacturing capabilities of

  7. HIGH RESOLUTION OPTICAL AND NIR SPECTRA OF HBC 722

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong-Eun; Park, Sunkyung [School of Space Research, Kyung Hee University, 1732 Deogyeong-daero, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Green, Joel D.; Cochran, William D. [Department of Astronomy, University of Texas at Austin, TX (United States); Kang, Wonseok; Lee, Sang-Gak [National Youth Space Center, 200 Deokheungyangjjok-gil, Dongil-myeon, Goheung-gun, Jeollanam-do 548-951 (Korea, Republic of); Sung, Hyun-Il, E-mail: jeongeun.lee@khu.ac.kr, E-mail: sunkyung@khu.ac.kr, E-mail: joel@astro.as.utexas.edu, E-mail: wdc@astro.as.utexas.edu, E-mail: wskang@kywa.or.kr, E-mail: sanggak@kywa.or.kr, E-mail: hisung@kasi.re.kr [Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu, Daejeon 305-348 (Korea, Republic of)

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s{sup −1} while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s{sup −1}. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R{sub ⊙}, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

  8. Adaptive optics with pupil tracking for high resolution retinal imaging.

    Science.gov (United States)

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  9. GFOC Project results: High Temperature / High Pressure, Hydrogen Tolerant Optical Fiber

    Energy Technology Data Exchange (ETDEWEB)

    E. Burov; A. Pastouret; E. Aldea; B. Overton; F. Gooijer; A. Bergonzo

    2012-02-12

    Tests results are given for exposure of multimode optical fiber to high temperatures (300 deg. C) and high partial pressure (15 bar) hydrogen. These results demonstrate that fluorine down doped optical fibers are much more hydrogen tolerant than traditional germanium doped multimode optical fibers. Also demonstrated is the similar hydrogen tolerance of carbon coated and non-carbon coated fibers. Model for reversible H2 impact in fiber versus T{sup o}C and H2 pressure is given. These results have significant impact for the longevity of use for distributed temperature sensing applications in harsh environments such as geothermal wells.

  10. High-speed Light Peak optical link for high energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Chang, F.X. [Academia Sinica, Taipei, Taiwan (China); Chiang, F. [FOCI Fiber Optic Comm., Inc., Hsinchu, Taiwan (China); Deng, B. [Hubei Polytechnic University, Huangshi, Hubei (China); Southern Methodist University, Dallas, TX (United States); Hou, J. [FOCI Fiber Optic Comm., Inc., Hsinchu, Taiwan (China); Hou, S., E-mail: suen@gate.sinica.edu.tw [Academia Sinica, Taipei, Taiwan (China); Liu, C.; Liu, T. [Southern Methodist University, Dallas, TX (United States); Teng, P.K. [Academia Sinica, Taipei, Taiwan (China); Wang, C.H. [National United University, Miaoli, Taiwan (China); Xu, T. [Shandong University, Ji' nan (China); Southern Methodist University, Dallas, TX (United States); Ye, J. [Southern Methodist University, Dallas, TX (United States)

    2014-11-21

    Optical links provide high speed data transmission with low mass fibers favorable for applications in high energy experiments. We report investigation of a compact Light Peak optical engine designed for data transmission at 4.8 Gbps. The module is assembled with bare die VCSEL, PIN diodes and a control IC aligned within a prism receptacle for light coupling to fiber ferrule. Radiation damage in the receptacle was examined with {sup 60}Co gamma ray. Radiation induced single event effects in the optical engine were studied with protons, neutrons and X-ray tests.

  11. Design of high-capacity fiber-optic transport systems

    Science.gov (United States)

    Liao, Zhi Ming

    2001-08-01

    We study the design of fiber-optic transport systems and the behavior of fiber amplifiers/lasers with the aim of achieving higher capacities with larger amplifier spacing. Solitons are natural candidates for transmitting short pulses for high-capacity fiber-optic networks because of its innate ability to use two of fiber's main defects, fiber dispersion and fiber nonlinearity to balance each other. In order for solitons to retain its dynamic nature, amplifiers must be placed periodically to restore powers to compensate for fiber loss. Variational analysis is used to study the long-term stability of a periodical- amplifier system. A new regime of operation is identified which allows the use of a much longer amplifier spacing. If optical fibers are the blood vessels of an optical communication system, then the optical amplifier based on erbium-doped fiber is the heart. Optical communication systems can avoid the use of costly electrical regenerators to maintain system performance by being able to optically amplify the weakened signals. The length of amplifier spacing is largely determined by the gain excursion experienced by the solitons. We propose, model, and demonstrate a distributed erbium-doped fiber amplifier which can drastically reduce the amount of gain excursion experienced by the solitons, therefore allowing a much longer amplifier spacing and superior stability. Dispersion management techniques have become extremely valuable tools in the design of fiber-optic communication systems. We have studied in depth the advantage of different arnplification schemes (lumped and distributed) for various dispersion compensation techniques. We measure the system performance through the Q factor to evaluate the added advantage of effective noise figure and smaller gain excursion. An erbium-doped fiber laser has been constructed and characterized in an effort to develop a test bed to study transmission systems. The presence of mode-partition noise in an erbium

  12. In vivo skin elastography with high-definition optical videos.

    Science.gov (United States)

    Zhang, Yong; Brodell, Robert T; Mostow, Eliot N; Vinyard, Christopher J; Marie, Hazel

    2009-08-01

    Continuous measurements of biomechanical properties of skin provide potentially valuable information to dermatologists for both clinical diagnosis and quantitative assessment of therapy. This paper presents an experimental study on in vivo imaging of skin elastic properties using high-definition optical videos. The objective is to (i) investigate whether skin property abnormalities can be detected in the computed strain elastograms, (ii) quantify property abnormalities with a Relative Strain Index (RSI), so that an objective rating system can be established, (iii) determine whether certain skin diseases are more amenable to optical elastography and (iv) identify factors that may have an adverse impact on the quality of strain elastograms. There are three steps in optical skin elastography: (i) skin deformations are recorded in a video sequence using a high-definition camcorder, (ii) a dense motion field between two adjacent video frames is obtained using a robust optical flow algorithm, with which a cumulative motion field between two frames of a larger interval is derived and (iii) a strain elastogram is computed by applying two weighted gradient filters to the cumulative motion data. Experiments were carried out using videos of 25 patients. In the three cases presented in this article (hypertrophic lichen planus, seborrheic keratosis and psoriasis vulgaris), abnormal tissues associated with the skin diseases were successfully identified in the elastograms. There exists a good correspondence between the shape of property abnormalities and the area of diseased skin. The computed RSI gives a quantitative measure of the magnitude of property abnormalities that is consistent with the skin stiffness observed on clinical examinations. Optical elastography is a promising imaging modality that is capable of capturing disease-induced property changes. Its main advantage is that an elastogram presents a continuous description of the spatial variation of skin properties on

  13. Ultra-high-speed optical and electronic distributed devices

    Energy Technology Data Exchange (ETDEWEB)

    Hietala, V.M.; Plut, T.A.; Kravitz, S.H.; Vawter, G.A.; Wendt, J.R.; Armendariz, M.G.

    1995-08-01

    This report summarizes work on the development of ultra-high-speed semiconductor optical and electronic devices. High-speed operation is achieved by velocity matching the input stimulus to the output signal along the device`s length. Electronic devices such as field-effect transistors (FET`s), should experience significant speed increases by velocity matching the electrical input and output signals along the device. Likewise, optical devices, which are typically large, can obtain significant bandwidths by velocity matching the light being generated, detected or modulated with the electrical signal on the device`s electrodes. The devices discussed in this report utilize truly distributed electrical design based on slow-wave propagation to achieve velocity matching.

  14. High speed sub-micrometric microscopy using optical polymer microlens

    Institute of Scientific and Technical Information of China (English)

    X.H.Zeng; J.Plain; S.Jradi; P.Renaud Goud; R.Deturche; P.Royer; R.Bachelot

    2009-01-01

    We report the high speed scanning submicronic microscopy (SSM) using a low cost polymer microlens integrated at the extremity of an optical fiber.These microlenses are fabricated by a free-radical photopolymerization method.Using a polymer microlens with a radius of curvature of 250 nm,a sub-micrometric gold pattern is imaged experimentally by SSM.Different distances between the tip and the sample are used with a high scanning speed of 200 cm/s.In particular,metallic absorption contrasts are described with an optical spatial resolution of 250 nm at the wavelength of 532 nm.Moreover,finite-difference time-domain (FDTD) simulations concerning the focal lengths of microlenses with different geometries and heights support the experimental data.

  15. Optical Variability Properties of High Luminosity AGN Classes

    Indian Academy of Sciences (India)

    C. S. Stalin; Gopal-Krishna; Ram Sagar; Paul J. Wiita

    2004-03-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range ≃ 0.2 to ≃ 2.2. The sample, matched in the optical luminosity – redshift (-) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single qusar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of INOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOVamplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020; 5GHz

  16. High field optical nonlinearity and the Kramers-Kronig relations.

    Science.gov (United States)

    Wahlstrand, J K; Cheng, Y-H; Milchberg, H M

    2012-09-14

    The nonlinear optical response to high fields is absolutely measured for the noble gas atoms He, Ne, Ar, Kr, and Xe. We find that the response is quadratic in the laser field magnitude up to the ionization threshold of each gas. Its size and quadratic dependence are well predicted by a Kramers-Kronig analysis employing known ionization probabilities, and the results are consistent with calculations using the time-dependent Schrödinger equation.

  17. Köhler illumination in high-resolution optical metrology

    Science.gov (United States)

    Sohn, Yeung Joon; Barnes, Brian M.; Howard, Lowell; Silver, Richard M.; Attota, Ravikiran; Stocker, Michael T.

    2006-03-01

    Accurate preparation of illumination is critical for high-resolution optical metrology applications such as linewidth and overlay measurements. To improve the detailed evaluation and alignment of the illumination optics, we have separated Koehler illumination into three components. The three Koehler illumination components are defined as full field spatial intensity variation (Koehler factor 1), angular intensity homogeneity (Koehler factor 2), and wavefront phase/intensity homogeneity (Koehler factor 3). We have also proposed a field aperture pattern transfer method to analyze the illumination properties with respect to systematic variations, such as the shape of the source, the intensity distribution at the back focal plane, and the displacements of elements along and off the optical axis. These factors were investigated in both ideal and practical illumination systems. In particular, any angular asymmetry in the illumination proves to have a detrimental effect upon the distribution of light that illuminates the target. Wavefront asymmetry is also studied in the context of an optical system with a coherent or partially coherent light source.

  18. Characterization of the optical parameters of high aspect ratio polymer micro-optical components

    Science.gov (United States)

    Krajewski, Rafal; Van Erps, Jurgen; Wissmann, Markus; Kujawinska, Malgorzata; Parriaux, Olivier; Tonchev, S.; Mohr, Jurgen; Thienpont, Hugo

    2008-04-01

    Over the last decades the significant grow of interest of photonics devices is observed in various fields of applications. Due to the market demands, the current research studies are focused on the technologies providing miniaturized, reliable low-cost micro-optical systems, particularly the ones featuring the fabrication of high aspect ratio structures. A high potential of these technologies comes from the fact that fabrication process is not limited to single optical components, but entire systems integrating sets of elements could be fabricated. This could in turn result in a significant saving on the assembly and packaging costs. We present a brief overview of the most common high aspect ratio fabrication technologies for micro-optical components followed by some characterization studies of these techniques. The sidewall quality and internal homogeneity will be considered as the most crucial parameters, having an impact on the wavefront propagation in the fabricated components. We show the characterization procedure and measurement results for components prototyped with Deep Proton Writing and glass micromachining technology replicated with Hot Embossing and Elastomeric Mould Vacuum Casting technology. We discuss the pros and cons for using these technologies for the production of miniaturized interferometers blocks. In this paper we present the status of our research on the new technology chain and we show the concept of microinterferometers to be fabricated within presented technology chain.

  19. Three-dimensional optical topography of brain activity in infants watching videos of human movement

    Science.gov (United States)

    Correia, Teresa; Lloyd-Fox, Sarah; Everdell, Nick; Blasi, Anna; Elwell, Clare; Hebden, Jeremy C.; Gibson, Adam

    2012-03-01

    We present 3D optical topography images reconstructed from data obtained previously while infants observed videos of adults making natural movements of their eyes and hands. The optical topography probe was placed over the temporal cortex, which in adults is responsible for cognitive processing of similar stimuli. Increases in oxyhaemoglobin were measured and reconstructed using a multispectral imaging algorithm with spatially variant regularization to optimize depth discrimination. The 3D optical topography images suggest that similar brain regions are activated in infants and adults. Images were presented showing the distribution of activation in a plane parallel to the surface, as well as changes in activation with depth. The time-course of activation was followed in the pixel which demonstrated the largest change, showing that changes could be measured with high temporal resolution. These results suggest that infants a few months old have regions which are specialized for reacting to human activity, and that these subtle changes can be effectively analysed using 3D optical topography.

  20. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

    Science.gov (United States)

    Sheehy, Christy K.; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-01-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone. PMID:26203370

  1. Active eye-tracking for an adaptive optics scanning laser ophthalmoscope.

    Science.gov (United States)

    Sheehy, Christy K; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

    2015-07-01

    We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.

  2. Active Figure Control Effects on Mounting Strategy for X-Ray Optics

    Science.gov (United States)

    Kolodziejczak, Jeffery J.; Atkins, Carolyn; Roche, Jacqueline M.; ODell, Stephen L.; Ramsey, Brian D.; Elsner, Ronald F.; Weisskopf, Martin C.; Gubarev, Mikhail V.

    2014-01-01

    As part of ongoing development efforts at MSFC, we have begun to investigate mounting strategies for highly nested xray optics in both full-shell and segmented configurations. The analytical infrastructure for this effort also lends itself to investigation of active strategies. We expect that a consequence of active figure control on relatively thin substrates is that errors are propagated to the edges, where they might affect the effective precision of the mounting points. Based upon modeling, we describe parametrically, the conditions under which active mounts are preferred over fixed ones, and the effect of active figure corrections on the required number, locations, and kinematic characteristics of mounting points.

  3. SMART composite high pressure vessels with integrated optical fiber sensors

    Science.gov (United States)

    Blazejewski, Wojciech; Czulak, Andrzej; Gasior, Pawel; Kaleta, Jerzy; Mech, Rafal

    2010-04-01

    In this paper application of integrated Optical Fiber Sensors for strain state monitoring of composite high pressure vessels is presented. The composite tanks find broad application in areas such as: automotive industry, aeronautics, rescue services, etc. In automotive application they are mainly used for gaseous fuels storage (like CNG or compressed Hydrogen). In comparison with standard steel vessels, composite ones have many advantages (i.e. high mechanical strength, significant weight reduction, etc). In the present work a novel technique of vessel manufacturing, according to this construction, was applied. It is called braiding technique, and can be used as an alternative to the winding method. During braiding process, between GFRC layers, two types of optical fiber sensors were installed: point sensors in the form of FBGs as well as interferometric sensors with long measuring arms (SOFO®). Integrated optical fiber sensors create the nervous system of the pressure vessel and are used for its structural health monitoring. OFS register deformation areas and detect construction damages in their early stage (ensure a high safety level for users). Applied sensor system also ensured a possibility of strain state monitoring even during the vessel manufacturing process. However the main application of OFS based monitoring system is to detect defects in the composite structure. An idea of such a SMART vessel with integrated sensor system as well as an algorithm of defect detection was presented.

  4. Optical constants of refractory oxides at high temperatures

    CERN Document Server

    Zeidler, Simon; Mutschke, Harald; 10.1051/0004-6361/201220459

    2013-01-01

    Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. A high-temperature-high-pressure-cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum (alpha-Al$_2$O$_3$), spinel (MgAl$_2$O$_4$), and alpha-quartz (SiO$_2$), temperature-dependent optical constants were measured from 300 K up to more than 900 K. Small particle spectra were also calculated from these data. All three examined oxides show a significant temperature dependence of their mid-IR bands. For the case of corundum, we find that the 13$\\mu$m emission feature - seen in the IR spec...

  5. KEPLER OBSERVATIONS OF RAPID OPTICAL VARIABILITY IN ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Mushotzky, R. F.; Edelson, R. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Baumgartner, W. [Laboratory for High Energy Astrophysics, NASA/GSFC, Code 662, Greenbelt, MD 20771 (United States); Gandhi, P., E-mail: richard@astro.umd.edu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

    2011-12-10

    Over three quarters in 2010-2011, Kepler monitored optical emission from four active galactic nuclei (AGNs) with {approx}30 minute sampling, >90% duty cycle, and {approx}<0.1% repeatability. These data determined the AGN optical fluctuation power spectral density (PSD) functions over a wide range in temporal frequency. Fits to these PSDs yielded power-law slopes of -2.6 to -3.3, much steeper than typically seen in the X-rays. We find evidence that individual AGNs exhibit intrinsically different PSD slopes. The steep PSD fits are a challenge to recent AGN variability models but seem consistent with first-order magnetorotational instability theoretical calculations of accretion disk fluctuations.

  6. Free-standing terahertz chiral meta-foils exhibiting strong optical activity and negative refractive index

    Science.gov (United States)

    Wu, Jianfeng; Ng, Binghao; Turaga, Shuvan P.; Breese, Mark B. H.; Maier, Stefan A.; Hong, Minghui; Bettiol, Andrew A.; Moser, Herbert O.

    2013-09-01

    A chiral meta-foil consisting of a self-supported square array of interconnected conjugated rosettes is demonstrated at terahertz frequencies. It exhibits strong optical activity and circular dichroism. Negative refractive index with a figure-of-merit as high as 4.2 is achieved, attributed to its free-standing nature. Experimental results are in good agreement with numerical simulation. Free-standing chiral meta-foils provide a unique approach to create a completely all-metal chiral metamaterial, which can be flexibly integrated into optical setups while eliminating dielectric insertion losses.

  7. Bio-optofluidics and Bio-photonics: Programmable Phase Optics activities at DTU Fotonik

    DEFF Research Database (Denmark)

    Bañas, Andrew Rafael; Palima, Darwin; Pedersen, Finn

    We present ongoing research and development activities for constructing a compact next generation BioPhotonics Workstation and a Bio-optofluidic Cell Sorter (cell-BOCS) for all-optical micromanipulation platforms utilizing low numerical aperture beam geometries. Unlike conventional high NA optical...... tweezers, the BioPhotonics workstation is e.g. capable of long range 3D manipulation. This enables a variety of biological studies such as manipulation of intricate microfabricated assemblies or for automated and parallel optofluidic cell sorting. To further reduce its overhead, we propose ways of making...

  8. Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

    Science.gov (United States)

    Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

    2016-01-28

    Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported

  9. Automated packaging platform for low-cost high-performance optical components manufacturing

    Science.gov (United States)

    Ku, Robert T.

    2004-05-01

    Delivering high performance integrated optical components at low cost is critical to the continuing recovery and growth of the optical communications industry. In today's market, network equipment vendors need to provide their customers with new solutions that reduce operating expenses and enable new revenue generating IP services. They must depend on the availability of highly integrated optical modules exhibiting high performance, small package size, low power consumption, and most importantly, low cost. The cost of typical optical system hardware is dominated by linecards that are in turn cost-dominated by transmitters and receivers or transceivers and transponders. Cost effective packaging of optical components in these small size modules is becoming the biggest challenge to be addressed. For many traditional component suppliers in our industry, the combination of small size, high performance, and low cost appears to be in conflict and not feasible with conventional product design concepts and labor intensive manual assembly and test. With the advent of photonic integration, there are a variety of materials, optics, substrates, active/passive devices, and mechanical/RF piece parts to manage in manufacturing to achieve high performance at low cost. The use of automation has been demonstrated to surpass manual operation in cost (even with very low labor cost) as well as product uniformity and quality. In this paper, we will discuss the value of using an automated packaging platform.for the assembly and test of high performance active components, such as 2.5Gb/s and 10 Gb/s sources and receivers. Low cost, high performance manufacturing can best be achieved by leveraging a flexible packaging platform to address a multitude of laser and detector devices, integration of electronics and handle various package bodies and fiber configurations. This paper describes the operation and results of working robotic assemblers in the manufacture of a Laser Optical Subassembly

  10. Precision glass molding of high-resolution diffractive optical elements

    Science.gov (United States)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

    2016-04-01

    The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

  11. Coverage Options for a Low cost, High Resolution Optical Constellation

    OpenAIRE

    Price, M E; Levett, W.; Graham, K.

    2003-01-01

    This paper presents the range of coverage options available to TopSat like small satellites, both singly and in a small constellation. TopSat is a low-cost, high resolution and image quality, optical small satellite, due for launch in October 2004. In particular, the paper considers the use of tuned, repeat ground track orbits to improve coverage for selected ground targets, at the expense of global coverage. TopSat is designed to demonstrate the capabilities of small satellites for high valu...

  12. Applications of nonimaging optics for very high solar concentrations

    Energy Technology Data Exchange (ETDEWEB)

    O`Gallagher, J.; Winston, R.

    1997-12-31

    Using the principles and techniques of nonimaging optics, solar concentrations that approach the theoretical maximum can be achieved. This has applications in solar energy collection wherever concentration is desired. In this paper, we survey recent progress in attaining and using high and ultrahigh solar fluxes. We review a number of potential applications for highly concentrated solar energy and the current status of the associated technology. By making possible new and unique applications for intense solar flux, these techniques have opened a whole new frontier for research and development of potentially economic uses of solar energy.

  13. Workshop on high heat load x-ray optics

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    A workshop on High Heat Load X-Ray Optics'' was held at Argonne National Laboratory on August 3--5, 1989. The object of this workshop was to discuss recent advances in the art of cooling x-ray optics subject to high heat loads from synchrotron beams. The cooling of the first optical element in the intense photon beams that will be produced in the next generation of synchrotron sources is recognized as one of the major challenges that must be faced before one will be able to use these very intense beams in future synchrotron experiments. Considerable advances have been made in this art during the last few years, but much work remains to be done before the heating problem can be said to be completely solved. Special emphasis was placed on recent cooling experiments and detailed finite element'' and finite difference'' calculations comparing experiment with theory and extending theory to optimize performance.

  14. Logical optical line terminal technologies towards flexible and highly reliable metro- and access-integrated networks

    Science.gov (United States)

    Okamoto, Satoru; Sato, Takehiro; Yamanaka, Naoaki

    2017-01-01

    In this paper, flexible and highly reliable metro and access integrated networks with network virtualization and software defined networking technologies will be presented. Logical optical line terminal (L-OLT) technologies and active optical distribution networks (ODNs) are the key to introduce flexibility and high reliability into the metro and access integrated networks. In the Elastic Lambda Aggregation Network (EλAN) project which was started in 2012, a concept of the programmable optical line terminal (P-OLT) has been proposed. A role of the P-OLT is providing multiple network services that have different protocols and quality of service requirements by single OLT box. Accommodated services will be Internet access, mobile front-haul/back-haul, data-center access, and leased line. L-OLTs are configured within the P-OLT box to support the functions required for each network service. Multiple P-OLTs and programmable optical network units (P-ONUs) are connected by the active ODN. Optical access paths which have flexible capacity are set on the ODN to provide network services from L-OLT to logical ONUs (L-ONUs). The L-OLT to L-ONU path on the active ODN provides a logical connection. Therefore, introducing virtualization technologies becomes possible. One example is moving an L-OLT from one P-OLT to another P-OLT like a virtual machine. This movement is called L-OLT migration. The L-OLT migration provides flexible and reliable network functions such as energy saving by aggregating L-OLTs to a limited number of P-OLTs, and network wide optical access path restoration. Other L-OLT virtualization technologies and experimental results will be also discussed in the paper.

  15. Improving acousto-optical interaction by high aspect ratio electrodes

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    In recent years experiments have shown that optical waves in waveguides can be modulated by mechanical stresses from surface acoustic waves (SAW), which have most of their energy density concentrated at the surface. In these experiments the SAWs are generated in piezoelectric materials...... by conventional interdigital transducers consisting of thin electrodes deposited at the surface. In this work the finite element method is employed to investigate if the acousto-optical interaction can be enhanced by generating the SAWs by interdigital transducers consisting of high aspect ratio electrodes....... With a periodic model it is first shown that these tall electrodes introduce several new confined SAW modes with slow phase velocities because of mechanical energy storage in the electrodes. The periodic model is then extended to a finite model by using perfectly matched layers at the substrate borders...

  16. Optical fiber transmission of high power excimer laser radiation.

    Science.gov (United States)

    Pini, R; Salimbeni, R; Vannini, M

    1987-10-01

    An experimental investigation of optical fiber transmission of high power excimer laser radiation is presented. Different types of commercially available UV fiber have been tested, measuring energy handling capabilities and transmission losses of short samples at the XeCl (308-nm) and KrF (249-nm) wavelengths by using a standard excimer laser. A power density dependent damage process has been observed over 1 GW/cm(2). Fiber losses due to different radii of curvature are also reported. Experimental results have been examined to evaluate the effectiveness of excimer laser transmission through optical fibers for such medical uses as laser angioplasty, including also a comparison between the use of KrF or XeCl emission lines for this purpose. Finally, optimum excimer laser characteristics to increase the energy coupling in fibers are discussed.

  17. Classically entangled optical beams for high-speed kinematic sensing

    CERN Document Server

    Berg-Johansen, Stefan; Stiller, Birgit; Banzer, Peter; Ornigotti, Marco; Giacobino, Elisabeth; Leuchs, Gerd; Aiello, Andrea; Marquardt, Christoph

    2015-01-01

    Tracking the kinematics of fast-moving objects is an important diagnostic tool for science and engineering. Existing optical methods include high-speed CCD/CMOS imaging, streak cameras, lidar, serial time-encoded imaging and sequentially timed all-optical mapping. Here, we demonstrate an entirely new approach to positional and directional sensing based on the concept of classical entanglement in vector beams of light. The measurement principle relies on the intrinsic correlations existing in such beams between transverse spatial modes and polarization. The latter can be determined from intensity measurements with only a few fast photodiodes, greatly outperforming the bandwidth of current CCD/CMOS devices. In this way, our setup enables two-dimensional real-time sensing with temporal resolution in the GHz range. We expect the concept to open up new directions in photonics-based metrology and sensing.

  18. TOPICAL REVIEW: Optics of high-performance electron microscopes

    Directory of Open Access Journals (Sweden)

    H H Rose

    2008-01-01

    Full Text Available During recent years, the theory of charged particle optics together with advances in fabrication tolerances and experimental techniques has lead to very significant advances in high-performance electron microscopes. Here, we will describe which theoretical tools, inventions and designs have driven this development. We cover the basic theory of higher-order electron optics and of image formation in electron microscopes. This leads to a description of different methods to correct aberrations by multipole fields and to a discussion of the most advanced design that take advantage of these techniques. The theory of electron mirrors is developed and it is shown how this can be used to correct aberrations and to design energy filters. Finally, different types of energy filters are described

  19. A conceptual design for a Cassegrain-mounted high-resolution optical spectrograph for large-aperture telescopes

    Science.gov (United States)

    Froning, Cynthia S.; Osterman, Steven; Burgh, Eric; Beasley, Matthew; Scowen, Paul; Veach, Todd; Jordan, Steven; Ebbets, Dennis; Lieber, Michael; deCino, James; Castilho, Bruno Vaz; Gneiding, Clemens; César de Oliveira, Antonio

    2013-09-01

    We present a conceptual design for a high-resolution optical spectrograph appropriate for mounting at Cassegrain on a large aperture telescope. The design is based on our work for the Gemini High Resolution Optical Spectrograph (CUGHOS) project. Our design places the spectrograph at Cassegrain focus to maximize throughput and blue wavelength coverage, delivering R=40,000 resolving power over a continuous 320-1050 nm waveband with throughputs twice those of current instruments. The optical design uses a two-arm, cross-dispersed echelle format with each arm optimized to maximize efficiency. A fixed image slicer is used to minimize optics sizes. The principal challenge for the instrument design is to minimize flexure and degradation of the optical image. To ensure image stability, our opto-mechanical design combines a cost-effective, passively stable bench employing a honeycomb aluminum structure with active flexure control. The active flexure compensation consists of hexapod mounts for each focal plane with full 6-axis range of motion capability to correct for focus and beam displacement. We verified instrument performance using an integrated model that couples the optical and mechanical design to image performance. The full end-to-end modeling of the system under gravitational, thermal, and vibrational perturbations shows that deflections of the optical beam at the focal plane are active control to meet the stability requirement. The design elements and high fidelity modeling process are generally applicable to instruments requiring high stability under a varying gravity vector.

  20. Study on a transient optical fiber high temperature measurement system

    Science.gov (United States)

    Cai, Lulu; Liu, Yusha; Wang, Yutian

    2009-07-01

    High temperature is one of the most important parameters in the fields of scientific research and industrial production. At present, thermocouple, thermo resistive and radiance thermometer are already technologically mature which can be adopted to measure the general temperature, but when it comes to the transient high temperature that changes pretty quickly in wretched conditions, those traditional pyrometers can not meet the requirements any more. In this paper, we designed a transient optical high temperature measurement system. First, design of the temperature measurement probe. The system took blackbody cavity sensor together with optical fiber to receive the measured signal, here, the integrated emissivity model of the blackbody cavity was established and the optimum structure parameters were confirmed. Secondly, design of the entire temperature measurement system. A contact-noncontact measurement method was applied, which is to make the blackbody cavity and the measured high-temperature source contact, the fiber probe and the blackbody cavity noncontact, as a result, the error caused by contact measurement is overcame and the precision is guaranteed at the same time. In addition, a fiber grating was introduced as the wavelength filter device which can realize the dynamic filter of narrow-band signals and reduce the impact of background light. Thirdly, signal processing. In this part, we applied labVIEW software and wavelet analysis method. All of the signal acquisition and processing were realized in the labVIEW environment. Through calling matlab in labVIEW, the signals from optical fiber detector were wavelet denoised and decomposed, thus the temperature information was extracted, and the temperature value was obtained. On basis of wavelet transformation, the paper adopted the 4dB wavelet with horizontal scale of 5 to realize the feature extraction and noise removal, parts of the signals before and after the wavelet noise removal were given and analyzed

  1. Assembling optically active and nonactive metamaterials with chiral units

    Directory of Open Access Journals (Sweden)

    Xiang Xiong

    2012-12-01

    Full Text Available Metamaterials constructed with chiral units can be either optically active or nonactive depending on the spatial configuration of the building blocks. For a class of chiral units, their effective induced electric and magnetic dipoles, which originate from the induced surface electric current upon illumination of incident light, can be collinear at the resonant frequency. This feature provides significant advantage in designing metamaterials. In this paper we concentrate on several examples. In one scenario, chiral units with opposite chiralities are used to construct the optically nonactive metamaterial structure. It turns out that with linearly polarized incident light, the pure electric or magnetic resonance (and accordingly negative permittivity or negative permeability can be selectively realized by tuning the polarization of incident light for 90°. Alternatively, units with the same chirality can be assembled as a chiral metamaterial by taking the advantage of the collinear induced electric and magnetic dipoles. It follows that for the circularly polarized incident light, negative refractive index can be realized. These examples demonstrate the unique approach to achieve certain optical properties by assembling chiral building blocks, which could be enlightening in designing metamaterials.

  2. Activation of cell signaling via optical manipulation of gold-coated liposomes encapsulating signaling molecules

    Science.gov (United States)

    Orsinger, Gabriel V.; Leung, Sarah J.; Romanowski, Marek

    2013-02-01

    Many diseases involve changes in cell signaling cascades, as seen commonly in drug resistant cancers. To better understand these intricate signaling events in diseased cells and tissues, experimental methods of probing cellular communication at a single to multi-cell level are required. We recently introduced a general platform for activation of selected signaling pathways by optically controlled delivery and release of water soluble factors using gold-coated liposomes. In the example presented here, we encapsulated inositol trisphosphate (IP3), a ubiquitous intracellular secondary messenger involved in GPCR and Akt signaling cascades, within 100 nm gold-coated liposomes. The high polarizability of the liposome's unique gold pseudo-shell allows stable optical trapping for subcellular manipulation in the presence of cells. We take this optical manipulation further by optically injecting IP3-containing liposomes into the cytosol of a single cell to initiate localized cell signaling. Upon optical injection of liposomal IP3 into a single ovarian carcinoma cell, we observed localized activation as reported by changes in Indo-1 fluorescence intensity. With established gap junctions between the injected cell and neighboring cells, we monitored propagation of this signaling to and through nearby cells.

  3. Optically-gated Non-latched High Gain Power Device

    Science.gov (United States)

    2008-11-21

    INTENSITY MODULATION OF PSD SWITCHING DYNAMICS 39 5.1. Optically-modulated Active Gate Control (OMAG) architecture for full controllability of turn-on... architecture for next- generation avionics, electromagnetic interference (EMI) is a critical issue [2, 3]. EMI immunity of these actuators from external jamming...TlissMT (o] Ns * I utut*n I/a^l Rh-( J.52«5E»84 [ mVC ] I 0«| 1.20S2JE-02 [I/O cm] aloha =| 07t627 Ml: Bulk concenfcation M • Mobility O ! Bull

  4. Brillouin optical reflectometer with a Brillouin active filter

    Science.gov (United States)

    Budylin, G. S.; Gorshkov, B. G.; Gorshkov, G. B.; Zhukov, K. M.; Paramonov, V. M.; Simikin, D. E.

    2017-07-01

    A new scheme of a fibre-optic Brillouin reflectometer is experimentally studied, in which the spectral line of spontaneous Brillouin scattering is selected by an active Brillouin filter represented by the tested fibre itself. To improve the reflectometer characteristics, a cyclic code and Raman amplification of the scattering signal are applied. With an averaging time of 5 min, scanning of 25 km of fibre with a spatial resolution of 4 m and a sampling resolution of 1 m are provided. The root-mean-square deviation in determining the Brillouin frequency is less than 1.1 MHz. The reflectometer sensitivity is evaluated with respect to the temperature changes and mechanical deformation.

  5. High-Performance Airborne Optical Carbon Dioxide Analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental species measurement on airborne atmospheric research craft is a demanding application for optical sensing techniques. Yet optical techniques offer many...

  6. High-Performance Airborne Optical Carbon Dioxide Analyzer Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental species measurement on airborne atmospheric research craft is a demanding application for optical sensing techniques. Yet optical techniques offer...

  7. Optical gain from vertical Ge-on-Si resonant-cavity light emitting diodes with dual active regions

    Science.gov (United States)

    Lin, Guangyang; Wang, Jiaqi; Huang, Zhiwei; Mao, Yichen; Li, Cheng; Huang, Wei; Chen, Songyan; Lai, Hongkai; Huang, Shihao

    2017-09-01

    Vertical resonant-cavity light emitting diodes with dual active regions consisting of highly n-doped Ge/GeSi multiple quantum wells (MQWs) and a Ge epilayer are proposed to improve the light emitting efficiency. The MQWs are designed to optically pump the underlying Ge epilayer under electric injection. Abundant excess carriers can be optically pumped into the Γ valley of the Ge epilayer apart from electric pumping. With the combination of a vertical cavity, the efficiency of the optical-pumping process was effectively improved due to the elongation of the optical length in the cavity. With the unique feature, optical gain from the Ge epilayer is observed between 1625 and 1700 nm at injection current densities of >1.528 kA/cm2. The demonstration of optical gain from the Ge epilayer indicates that this strategy can be generally useful for Si-based light sources with indirect band materials.

  8. High Speed and High Spatial Density Parameter Measurement Using Fiber Optic Sensing Technology

    Science.gov (United States)

    Parker, Allen R. Jr. (Inventor); Chan, Hon Man (Inventor); Richards, William Lance (Inventor); Piazza, Anthony (Inventor); Hamory, Philip J (Inventor)

    2017-01-01

    The present invention is an improved fiber optic sensing system (FOSS) having the ability to provide both high spatial resolution and high frequency strain measurements. The inventive hybrid FOSS fiber combines sensors from high acquisition speed and low spatial resolution Wavelength-Division Multiplexing (WDM) systems and from low acquisition speed and high spatial resolution Optical Frequency Domain Reflection (OFDR) systems. Two unique light sources utilizing different wavelengths are coupled with the hybrid FOSS fiber to generate reflected data from both the WDM sensors and OFDR sensors operating on a single fiber optic cable without incurring interference from one another. The two data sets are then de-multiplexed for analysis, optionally with conventionally-available WDM and OFDR system analyzers.

  9. A high average power electro-optic switch using KTP

    Energy Technology Data Exchange (ETDEWEB)

    Ebbers, C.A.; Cook, W.M.; Velsko, S.P.

    1994-04-01

    High damage threshold, high thermal conductivity, and small thermo-optic coefficients make KTiOPO{sub 4} (KTP) an attractive material for use in a high average power Q-switch. However, electro-chromic damage and refractive index homogeneity have prevented the utilization of KTP in such a device in the past. This work shows that electro-chromic damage is effectively suppressed using capacitive coupling, and a KTP crystal can be Q-switched for 1.5 {times} 10{sup 9} shots without any detectable electro-chromic damage. In addition, KTP with the high uniformity and large aperture size needed for a KTP electro-optic Q-switch can be obtained from flux crystals grown at constant temperature. A thermally compensated, dual crystal KTP Q-switch, which successfully produced 50 mJ pulses with a pulse width of 8 ns (FWHM), has been constructed. In addition, in off-line testing the Q-switch showed less than 7% depolarization at an average power loading of 3.2 kW/cm{sup 2}.

  10. Optical monitoring of high power direct diode laser cladding

    Science.gov (United States)

    Liu, Shuang; Farahmand, Parisa; Kovacevic, Radovan

    2014-12-01

    Laser cladding is one of the most advanced surface modification techniques which can be used to build and repair high-value components. High power direct diode laser (HPDDL) offers unique quality and cost advantages over other lasers (CO2, Nd:YAG). Especially its rectangular laser beam with top-hat intensity distribution makes HPDDL an ideal tool for large area cladding. In order to utilize this technique successfully, the development of on-line monitoring and process control is necessary. In this study, an optical monitoring system consisting of a high-speed CCD camera, a pyrometer, and an infrared camera was used to analyze the mass- and heat-transfer in the cladding process. The particle transport in flight was viewed by a high-speed CCD camera; the interaction between powder flow and laser beam was observed by an infrared camera; and the thermal behavior of the molten pool was recorded by the pyrometer and the infrared camera. The effects of the processing parameters on the laser attenuation, particle heating and clad properties were investigated based on the obtained signals. The optical monitoring method improved the understanding about mutual interrelated phenomena in the cladding process.

  11. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators...... (EAMs). Wavelength conversion and signal regeneration in EAMs is discussed at 10 and 40 Gbit/s. The finite carrier sweep-out time is shown to limit the EAM performance. Four-wave mixing (FWM) in SOAs is almost instantaneous. However, with increasing bit rates and advanced processing functionalities some...... limitations arise. These limitations are elucidated by studying bi-directional simultaneous clear and drop (de-multiplexing) for a 4x40 Gbit/s signal. The simultaneous clearing and de-multiplexing (drop) of an optical time division multiplexing signal channel for an 8x40 Gbit/s signal is investigated...

  12. High Resolution Optical and NIR Spectra of HBC 722

    CERN Document Server

    Lee, Jeong-Eun; Green, Joel D; Cochran, William D; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il

    2015-01-01

    We present the results of high resolution (R$\\ge$30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in optical/near-IR with the BOES, HET-HRS, and IGRINS spectrographs, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first two years. The Half-Width at Half-Depth (HWHD) of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitt...

  13. Engineering near-infrared single-photon emitters with optically active spins in ultrapure silicon carbide

    Science.gov (United States)

    Fuchs, F.; Stender, B.; Trupke, M.; Simin, D.; Pflaum, J.; Dyakonov, V.; Astakhov, G. V.

    2015-07-01

    Vacancy-related centres in silicon carbide are attracting growing attention because of their appealing optical and spin properties. These atomic-scale defects can be created using electron or neutron irradiation; however, their precise engineering has not been demonstrated yet. Here, silicon vacancies are generated in a nuclear reactor and their density is controlled over eight orders of magnitude within an accuracy down to a single vacancy level. An isolated silicon vacancy serves as a near-infrared photostable single-photon emitter, operating even at room temperature. The vacancy spins can be manipulated using an optically detected magnetic resonance technique, and we determine the transition rates and absorption cross-section, describing the intensity-dependent photophysics of these emitters. The on-demand engineering of optically active spins in technologically friendly materials is a crucial step toward implementation of both maser amplifiers, requiring high-density spin ensembles, and qubits based on single spins.

  14. Actively phase-controlled coupling between plasmonic waveguides via in-between gain-assisted nanoresonator: nanoscale optical logic gates.

    Science.gov (United States)

    Ho, Kum-Song; Han, Yong-Ha; Ri, Chol-Song; Im, Song-Jin

    2016-08-15

    The development of nanoscale optical logic gates has attracted immense attention due to increasing demand for ultrahigh-speed and energy-efficient optical computing and data processing, however, suffers from the difficulty in precise control of phase difference of the two optical signals. We propose a novel conception of nanoscale optical logic gates based on actively phase-controlled coupling between two plasmonic waveguides via an in-between gain-assisted nanoresonator. Precise control of phase difference between the two plasmonic signals can be performed by manipulating pumping rate at an appropriate frequency detuning, enabling a high contrast between the output logic states "1" and "0." Without modification of the structural parameters, different logic functions can be provided. This active nanoscale optical logic device is expected to be quite energy-efficient with ideally low energy consumption on the order of 0.1 fJ/bit. Analytical calculations and numerical experiments demonstrate the validity of the proposed concept.

  15. Starburst-AGN mixing: II. Optically-selected active galaxies

    CERN Document Server

    Davies, Rebecca L; Ho, I-Ting; Dopita, Michael A

    2014-01-01

    We use 4 galaxies from the Calar Alto Legacy Integral Field Area (CALIFA) survey with clear signs of accretion onto supermassive black holes to investigate the relative contribution of star-formation and active galactic nucleus (AGN) activity to the line-emission of each galaxy as a function of radius. The combination of star-formation and AGN activity produces curved "mixing sequences" on standard optical diagnostic diagrams, and the fraction of emission due to AGN activity decreases smoothly with distance from the centre of the galaxy. We use the AGN activity profiles to calculate the size of the AGN narrow line regions, which have radii of ~ 6.3 kpc. We calculate the fractional contribution of the star-formation and the AGN activity to the global Halpha, [O II] $\\lambda \\lambda$ 3727,3729 and [O III] $\\lambda$ 5007 luminosities of each galaxy, and show that both ionization sources contribute significantly to the emission in all three lines. We use weighted combinations of stellar and AGN photoionization mo...

  16. A design of High-precision High-Voltage Fiber-Optic Analog Signal Isolation Converter

    Institute of Scientific and Technical Information of China (English)

    李建伟; 许留伟; 刘小宁; 杨雷

    2002-01-01

    This paper introduces a design of high-prectison high-voltage fiber-optic analog sig-nal isoaltion converter based on the technology of Voltage-to-Fequency (V/F)and Frequency -to Voltage(F/V) conversion It describes the principle ,system configuration and hardware design

  17. Optical activity studies of hydrogen-deuterium exchange

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, L.J.

    1990-01-01

    The potassium complexes of racemic and optically active forms of 1,2-propanediaminetriacetatoacetic acid nickel-ate (II) were prepared stoichiometrically by two different experimental procedures. The complexes were characterized by UV-VIS absorption spectroscopy, infrared spectroscopy, and thermal analysis. Circular dichroism and optical rotatory dispersion values were obtained on the optically active complexes. TGA and IR spectroscopy techniques suggest that {Delta}-K (Ni(R ({minus})HPDTA)) H{sub 2}O (1)and {Lambda}-K (Ni(S (+)HPDTA)) H{sub 2}O (2) have different configurations in solution than in the solid state. Solid complexes of (1) are theorized to have the nickel (II) ion bound pentadentate to the PDTA ligand and unidentate to a water molecule. The free carboxyl arm of the PDTA ligand is protonated. Dissolution of the complexes results in rotational changes which occur with time. The rate of rotational change has been kinetically measured, which results in three pH dependent rate constants. An isotope effect for such reactions in H{sub 2}O and D{sub 2}O has been measured. The base-catalyzed hydrogen-deuterium exchange of the out-of-plane glycinate rings of (1) and (2) complexes has been determined for three of the four glycinate protons by ORD. The rate of hydrogen-deuterium exchange is extremely slow and consecutive proton exchanges are not independent of one another over sufficiently long periods, such that measurement of {alpha}{sub {infinity}} are calculated by three differing mathematical models and applied to the calculation of the hydrogen-deuterium rate constants.

  18. 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.

  19. Combining an Optical Resonance Biosensor with Enzyme Activity Kinetics to Understand Protein Adsorption and Denaturation

    OpenAIRE

    Wilson, Kerry A.; Finch, Craig A.; Anderson, Phillip; Vollmer, Frank; Hickman, James J.

    2014-01-01

    Understanding protein adsorption and resultant conformation changes on modified and unmodified silicon dioxide surfaces is a subject of keen interest in biosensors, microfluidic systems and for medical diagnostics. However, it has been proven difficult to investigate the kinetics of the adsorption process on these surfaces as well as understand the topic of the denaturation of proteins and its effect on enzyme activity. A highly sensitive optical whispering gallery mode (WGM) resonator was us...

  20. Single-side-band optical modulation in SCM systems for high-speed optical transmission

    Institute of Scientific and Technical Information of China (English)

    李忠义; 廖同庆

    2009-01-01

    In order to decrease dispersion penalty and increase the optical bandwidth efficiency,an optical single-side-band modulation(SSBM) scheme in sub-carrier multiplexing(SCM) is proposed.The principle of the SSBM is analytically presented,and a configuration for generating optical SSB signal is proposed using a balanced Mach-Zehnder electro-optic modulator.

  1. Dispersion of optical activity of magnesium sulfite hexahydrate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Dimov, T; Bunzarov, Zh; Iliev, I; Petkova, P; Tzoukrovski, Y, E-mail: dimov@shu-bg.ne

    2010-11-01

    The magnesium sulfite hexahydrate (MgSO{sub 3}.6H{sub 2}O) crystals are unique because they are the only representative (with sodium periodate) of the crystallographic class C{sub 3} (without a center of symmetry). The crystal symmetry suggests presence of nonlinearity, piezo- and pyro-electric properties and gyrotropy as well. Single crystals of MgSO{sub 3}.6H{sub 2}O (pure and doped with Ni, Co and Zn) for the time being are grown only by the original method developed in the Laboratory for Crystal growth at the Faculty of Physics in Sofia University. The first results of optical activity of pure MgSO{sub 3}.6H{sub 2}O and Zn doped MgSO{sub 3}.6H{sub 2}O crystals are described and analyzed in a wide spectral range. The optical activity manifests itself in the direction (0001) as a rotation of the polarization plane.

  2. High-Speed Optical Home Network Using Graded Index Plastic Optical Fibers for a Smart House

    Directory of Open Access Journals (Sweden)

    Tetsuya Toma

    2013-11-01

    Full Text Available In this paper, we propose a home monitoring, management, and communication system (HMMCS with high-seed optical home network for a smart house in a smart city to optimize the energy usage and to create a comfortable environment. The HMMCS monitors the interior environment and the electricity consumption of all electric appliances. It also records log data, shares information and movies/images, and cross-connects with web services. We assembled small-scale prototype HMMCS and developed application software with an original user interface. The results of a test run reveal that the HMMCS can monitor electricity consumption and interior environments in real time and can control different types of electric appliances including servers that play movies. The maximum data traffic load in a smart house has been calculated using the measured traffic data. Moreover, we found that a smart house with HMMCS inevitably requires a high-speed optical network for real-time, high-quality responses.

  3. Highly Linear, Broadband Optical Modulator Based on Electro-optic Polymer

    CERN Document Server

    Zhang, Xingyu; Lin, Che-yun; Wang, Alan X; Hosseini, Amir; Chen, Ray T

    2014-01-01

    In this paper, we present the design, fabrication and characterization of a traveling wave directional coupler modulator based on electro-optic polymer, which is able to provide both high linearity and broad bandwidth. The high linearity is realized by introducing domain-inversion technique in the two-domain directional coupler. A travelling wave electrode is designed to function with bandwidth-length product of 302GHz cm, by achieving low microwave loss, excellent impedance matching and velocity matching, as well as smooth electric field profile transformation. The 3-dB bandwidth of the device is measured to be 10GHz. The spurious free dynamic range of about 110dB Hz^(2/3) is measured over the modulation frequency range 2-8GHz. To the best of our knowledge, such high linearity is first measured at the frequency up to 8GHz. In addition, a 1-to-2 multi-mode interference 3dB-splitter, a photobleached refractive index taper and a quasi-vertical taper are used to reduce the optical insertion loss of the device.

  4. Cycloaddition in peptides for high-capacity optical storage

    DEFF Research Database (Denmark)

    Lohse, Brian; Berg, Rolf Henrik; Hvilsted, Søren

    2006-01-01

    Photodimerization of chromophores attached to a short peptide chain is investigated for high-capacity optical digital storage with UV lasers. The length and rigidity of the peptide chain assure an optimal distance and orientation of the chromophores for effective photodimerization. Using a theory...... developed by Tomlinson, the absorption cross section for the dimerization process in a uracil-ornithine-based hexamer is determined to be 9 x 10(-20) cm(2). A large change in the transmission due to irradiation in the UV area may make it possible to realize multilevel storage in a thin film of the peptides....

  5. High Performance Small Optically Pumped Caesium Beam Frequency Standard

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-Wei; YANG Dong-Hai

    2007-01-01

    An experiment of a high performance small optically pumped caesium (Cs) beam frequency standard is reported. An extended cavity diode laser works as the probing laser, of which the frequency is stabilized by the Zeeman modulation method. The running parameters of the frequency standard are dynamically optimized via digital servo electronics. The experimental setup improves the frequency stability up to 1.8 × 10-12 atτ= 1 s and about 1.0 × 10~13 at τ= 105 s (Allan deviation).

  6. High Speed Optical Tomography System for Imaging Dynamic Transparent Media

    Science.gov (United States)

    McMackin, Lenore; Hugo, Ronald J.; Pierson, R. E.; Truman, C. R.

    1997-11-01

    We describe the design and operation of a high speed optical tomography system for measuring two-dimensional images of a dynamic phase object at a rate of 5 kHz. Data from a set of eight Hartmann wavefront sensors is back-projected to produce phase images showing the details of the inner structure of a heated air flow. The tomographic reconstructions have a spatial resolution of approximately 2.0 mm and can measure temperature variations across the flow with an accuracy of about 0.7 C. Series of animated reconstructions at different downstream locations illustrate the development of flow structure and the effect of acoustic flow forcing.

  7. High speed OFDM-CDMA optical access network.

    Science.gov (United States)

    Guo, X; Wang, Q; Zhou, L; Fang, L; Wonfor, A; Penty, R V; White, I H

    2016-04-15

    We demonstrate the feasibility of a 16 × 3.75 Gb/s (60 Gb/s aggregate) Orthogonal frequency division multiplexing-code division multiple access passive optical network for next-generation access applications. 3.75 Gb/s PON channel transmission over 25 km single-mode fiber shows 0.1 dB dispersion and 0.9 dB crosstalk penalties. Advantages of the system include high capacity, enhanced spectral efficiency, coding gain, and networking functions such as increased security and single-wavelength operation.

  8. Anomalous dynamic behaviour of optically trapped high aspect ratio nanowires

    CERN Document Server

    Toe, Wen Jun; Angstmann, Christopher; Gao, Qiang; Tan, Hark Hoe; Jagadish, Chennupati; Henry, Bruce; Reece, Peter J

    2015-01-01

    We investigate the dynamics of high aspect ratio nanowires trapped axially in a single gradient force optical tweezers. A power spectrum analysis of the Brownian dynamics reveals a broad spectral resonance of the order of a kHz with peak properties that are strongly dependent on the input trapping power. Modelling of the dynamical equations of motion of the trapped nanowire that incorporate non-conservative effects through asymmetric coupling between translational and rotational degrees of freedom provides excellent agreement with the experimental observations. An associated observation of persistent cyclical motion around the equilibrium trapping position using winding analysis provides further evidence for the influence of non-conservative forces.

  9. Reflectively Coupled Waveguide Photodetector for High Speed Optical Interconnection

    Directory of Open Access Journals (Sweden)

    Shih-Hsiang Hsu

    2010-12-01

    Full Text Available To fully utilize GaAs high drift mobility, techniques to monolithically integrate In0.53Ga0.47As p-i-n photodetectors with GaAs based optical waveguides using total internal reflection coupling are reviewed. Metal coplanar waveguides, deposited on top of the polyimide layer for the photodetector’s planarization and passivation, were then uniquely connected as a bridge between the photonics and electronics to illustrate the high-speed monitoring function. The photodetectors were efficiently implemented and imposed on the echelle grating circle for wavelength division multiplexing monitoring. In optical filtering performance, the monolithically integrated photodetector channel spacing was 2 nm over the 1,520–1,550 nm wavelength range and the pass band was 1 nm at the −1 dB level. For high-speed applications the full-width half-maximum of the temporal response and 3-dB bandwidth for the reflectively coupled waveguide photodetectors were demonstrated to be 30 ps and 11 GHz, respectively. The bit error rate performance of this integrated photodetector at 10 Gbit/s with 27-1 long pseudo-random bit sequence non-return to zero input data also showed error-free operation.

  10. High-grade optical polydimethylsiloxane for microfluidic applications.

    Science.gov (United States)

    Lovchik, Robert Dean; Wolf, Heiko; Delamarche, Emmanuel

    2011-12-01

    Commercially available polydimethylsiloxane (PDMS) elastomers, such as Sylgard 184® are widely used in soft lithography and for microfluidic applications. These PDMS elastomers contain fillers to enhance their mechanical stability. The reinforcing fillers, often sub-micrometer small SiO(2) particles, tend to aggregate, swell with water, and thereby become cognoscible in a way that can strongly interfere with the visualization of micro-scale events taking place next to PDMS structures. As PDMS microfluidics are often used for studying cells and micro-/nanoparticles and for creating/handling nanodroplets, it has become highly desirable to employ a PDMS having high optical quality and that allows microscopy observation without artifacts. Here, we present a PDMS formulation that is free of fillers and has sufficiently low viscosity to perform a filtration step of the mixed prepolymers before curing. By molding a bi-layer microfluidic network (MFN), composed of a thin filler-free PDMS layer and a thicker Sylgard 184® backing layer, PDMS MFNs featuring both high optical quality and mechanical stability, can be fabricated.

  11. High frame rate CCD camera with fast optical shutter

    Energy Technology Data Exchange (ETDEWEB)

    Yates, G.J.; McDonald, T.E. Jr. [Los Alamos National Lab., NM (United States); Turko, B.T. [Lawrence Berkeley National Lab., CA (United States)

    1998-09-01

    A high frame rate CCD camera coupled with a fast optical shutter has been designed for high repetition rate imaging applications. The design uses state-of-the-art microchannel plate image intensifier (MCPII) technology fostered/developed by Los Alamos National Laboratory to support nuclear, military, and medical research requiring high-speed imagery. Key design features include asynchronous resetting of the camera to acquire random transient images, patented real-time analog signal processing with 10-bit digitization at 40--75 MHz pixel rates, synchronized shutter exposures as short as 200pS, sustained continuous readout of 512 x 512 pixels per frame at 1--5Hz rates via parallel multiport (16-port CCD) data transfer. Salient characterization/performance test data for the prototype camera are presented, temporally and spatially resolved images obtained from range-gated LADAR field testing are included, an alternative system configuration using several cameras sequenced to deliver discrete numbers of consecutive frames at effective burst rates up to 5GHz (accomplished by time-phasing of consecutive MCPII shutter gates without overlap) is discussed. Potential applications including dynamic radiography and optical correlation will be presented.

  12. Optically Thin Metallic Films for High-radiative-efficiency Plasmonics

    CERN Document Server

    Yang, Yi; Hsu, Chia Wei; Miller, Owen D; Joannopoulos, John D; Soljačić, Marin

    2016-01-01

    Plasmonics enables deep-subwavelength concentration of light and has become important for fundamental studies as well as real-life applications. Two major existing platforms of plasmonics are metallic nanoparticles and metallic films. Metallic nanoparticles allow efficient coupling to far field radiation, yet their synthesis typically leads to poor material quality. Metallic films offer substantially higher quality materials, but their coupling to radiation is typically jeopardized due to the large momentum mismatch with free space. Here, we propose and theoretically investigate optically thin metallic films as an ideal platform for high-radiative-efficiency plasmonics. For far-field scattering, adding a thin high-quality metallic substrate enables a higher quality factor while maintaining the localization and tunability that the nanoparticle provides. For near-field spontaneous emission, a thin metallic substrate, of high quality or not, greatly improves the field overlap between the emitter environment and ...

  13. High Resolution Optical Spectra of HBC 722 after Outburst

    CERN Document Server

    Lee, Jeong-Eun; Lee, Sang-Gak; Sung, Hyun-Il; Lee, Byeong-Cheol; Sung, Hwankyung; Green, Joel D; Jeon, Young-Beom

    2011-01-01

    We report the results of our high resolution optical spectroscopic monitoring campaign ($\\lambda$ = 3800 -- 8800 A, R = 30000 -- 45000) of the new FU Orionis-type object HBC 722. We observed HBC 722 with the BOES 1.8-m telescope between 2010 November 26 and 2010 December 29 and FU Orionis itself on 2011 January 26. We detect a number of previously unreported high-resolution K I and Ca II lines beyond 7500 A. We resolve the H$\\alpha$ and Ca II line profiles into three velocity components, which we attribute to both disk and outflow. The increased accretion during outburst can heat the disk to produce the relatively narrow absorption feature and launch outflows appearing as high velocity blue and redshifted broad features.

  14. FSK Modulation Scheme for High-Speed Optical Transmission

    Institute of Scientific and Technical Information of China (English)

    Nan Chi; Wuliang Fang; Yufeng Shao; Junwen Zhang; Li Tao

    2012-01-01

    In this paper, we describe the generation, detection, and performance of frequency-shift keying (FSK) for high-speed optical transmission and label switching. A non-return-to-zero (NRZ) FSK signal is generated by using two continuous-wave (CW) lasers, one Mach-Zehnder modulator (MZM), and one Mach-Zehnder delay interferometer (MZDI). An RZ-FSK signal is generated by cascading a dual-arm MZM, which is driven by a sinusoidal voltage at half the bit rate. Demodulation can be achieved on 1 bit rate through one MZDI or an array waveguide grating (AWG) demultiplexer with balanced detection. We perform numerical simulation on two types of frequency modulation schemes using MZM or PM, and we determine the effect of frequency tone spacing (FTS) on the generated FSK signal. In the proposed scheme, a novel frequency modulation format has transmission advantages compared with traditional modulation formats such as RZ and differential phase-shift keying (DPSK), under varying dispersion management. The performance of an RZ-FSK signal in a 4 x 40 Gb/s WDM transmission system is discussed. We experiment on transparent wavelength conversion based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) and in a highly nonlinear dispersion shifted fiber (HNDSF) for a 40 Gb/s RZ-FSK signal. The feasibility of all-optical signal processing of a high-speed RZ-FSK signal is confirmed. We also determine the receiver power penalty for the RZ-FSK signal after a 100 km standard single-mode fiber (SMF) transmission link with matching dispersion compensating fiber (DCF), under the post-compensation management scheme. Because the frequency modulation format is orthogonal to intensity modulation and vector modulation (polarization shift keying), it can be used in the context of the combined modulation format to decrease the data rate or enhance the symbol rate. It can also be used in orthogonal label-switching as the modulation format for the payload or the label. As an example, we

  15. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry

    Science.gov (United States)

    Ha, Sohmyung; Khraiche, Massoud L.; Akinin, Abraham; Jing, Yi; Damle, Samir; Kuang, Yanjin; Bauchner, Sue; Lo, Yu-Hwa; Freeman, William R.; Silva, Gabriel A.; Cauwenberghs, Gert

    2016-10-01

    Objective. Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. Approach. The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. Main results. A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. Significance. Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.

  16. Magneto-Optic Fiber Bragg Gratings with Application to High-Resolution Magnetic Field Sensors

    Institute of Scientific and Technical Information of China (English)

    Bao-Jian Wu; Ying Yang; Kun Qiu

    2008-01-01

    Magneto-optic fiber Bragg gratings (MFBG) based on magneto-optic materials have a lot of potential applications for sensing and optical signal processing. The transmission and reflection spectra of guided optical waves in the MFBG are investigated. According to the sensitivity of MFBG spectral lines to the magneto-optic coupling intensity varying with applied magnetic field, a novel magnetic field sensor of high-resolution up to 0.01 nm/(kA/m) is predicted.

  17. Highly Reliable PON Optical Splitters for Optical Access Networks in Outside Environments

    Science.gov (United States)

    Watanabe, Hiroshi; Araki, Noriyuki; Fujimoto, Hisashi

    Broadband optical access services are spreading throughout the world, and the number of fiber to the home (FTTH) subscribers is increasing rapidly. Telecom operators are constructing passive optical networks (PONs) to provide optical access services. Externally installed optical splitters for PONs are very important passive devices in optical access networks, and they must provide satisfactory performance as outdoor plant over long periods. Therefore, we calculate the failure rate of optical access networks and assign a failure rate to the optical splitters in optical access networks. The maximum cumulative failure rate of 1 × 8 optical splitters was calculated as 0.025 for an optical access fiber length of 2.1km and a 20-year operating lifetime. We examined planar lightwave circuit (PLC) type optical splitters for use as outside plant in terms of their optical characteristics and environmental reliability. We confirmed that PLC type optical splitters have sufficient optical performance for a PON splitter and sufficient reliability as outside plant in accordance with ITU-T standard values. We estimated the lifetimes of three kinds of PLC type optical splitters by using accelerated aging tests. The estimated failure rate of these splitters installed in optical access networks was below the target value for the cumulative failure rate, and we confirmed that they have sufficient reliability to maintain the quality of the network service. We developed 1 × 8 optical splitter modules with plug and socket type optical connectors and optical fiber cords for optical aerial closures designed for use as outside plant. These technologies make it easy to install optical splitters in an aerial optical closure. The optical splitter modules have sufficient optical performance levels for PONs because the insertion loss at the commercially used wavelengths of 1.31 and 1.55µm is less than the criterion established by ITU-T Recommendation G.671 for optical splitters. We performed a

  18. A New, Adaptable, Optical High-Resolution 3-Axis Sensor

    Directory of Open Access Journals (Sweden)

    Niels Buchhold

    2017-01-01

    Full Text Available This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD. The downstream microcontroller’s software identifies the geometric shape’s center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels, the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user’s range of motion (stroke and force. This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability.

  19. A New, Adaptable, Optical High-Resolution 3-Axis Sensor.

    Science.gov (United States)

    Buchhold, Niels; Baumgartner, Christian

    2017-01-27

    This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller's software identifies the geometric shape's center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user's range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability.

  20. A New, Adaptable, Optical High-Resolution 3-Axis Sensor

    Science.gov (United States)

    Buchhold, Niels; Baumgartner, Christian

    2017-01-01

    This article presents a new optical, multi-functional, high-resolution 3-axis sensor which serves to navigate and can, for example, replace standard joysticks in medical devices such as electric wheelchairs, surgical robots or medical diagnosis devices. A light source, e.g., a laser diode, is affixed to a movable axis and projects a random geometric shape on an image sensor (CMOS or CCD). The downstream microcontroller’s software identifies the geometric shape’s center, distortion and size, and then calculates x, y, and z coordinates, which can be processed in attached devices. Depending on the image sensor in use (e.g., 6.41 megapixels), the 3-axis sensor features a resolution of 1544 digits from right to left and 1038 digits up and down. Through interpolation, these values rise by a factor of 100. A unique feature is the exact reproducibility (deflection to coordinates) and its precise ability to return to its neutral position. Moreover, optical signal processing provides a high level of protection against electromagnetic and radio frequency interference. The sensor is adaptive and adjustable to fit a user’s range of motion (stroke and force). This recommendation aims to optimize sensor systems such as joysticks in medical devices in terms of safety, ease of use, and adaptability. PMID:28134824

  1. High-sensitive scanning laser magneto-optical imaging system.

    Science.gov (United States)

    Murakami, Hironaru; Tonouchi, Masayoshi

    2010-01-01

    A high-sensitive scanning laser magneto-optical (MO) imaging system has been developed. The system is mainly composed of a laser source, galvano meters, and a high-sensitive differential optical-detector. Preliminary evaluation of system performance by using a Faraday indicator with a Faraday rotation coefficient of 3.47 x 10(-5) rad/microm Oe shows a magnetic sensitivity of about 5 microT, without any need for accumulation or averaging processing. Using the developed MO system we have succeeded in the fast and quantitative imaging of a rotationally symmetric magnetic field distribution around an YBa(2)Cu(3)O(7-delta) (YBCO) strip line applied with dc-biased current, and also succeeded in the detection of quantized fine signals corresponding to magnetic flux quantum generation in a superconducting loop of an YBCO Josephson vortex flow transistor. Thus, the developed system enables us not only to do fast imaging and local signal detection but also to directly evaluate both the strength and direction of a magnetic signal.

  2. Generalized OFDM (GOFDM) for ultra-high-speed optical transmission.

    Science.gov (United States)

    Djordjevic, Ivan; Arabaci, Murat; Xu, Lei; Wang, Ting

    2011-03-28

    We propose a coded N-dimensional modulation scheme suitable for ultra-high-speed serial optical transport. The proposed scheme can be considered as a generalization of OFDM, and hence, we call it as generalized OFDM (GOFDM). In this scheme, the orthogonal subcarriers are used as basis functions and the signal constellation points are defined over this N-dimensional linear space. To facilitate implementation, we propose using N-dimensional pulse-amplitude modulation (ND-PAM) as the signal constellation diagram, which is obtained as the N-ary Cartesian product of one-dimensional PAM. In conventional OFDM, QAM/PSK signal constellation points are transmitted over orthogonal subcarriers and then they are multiplexed together in an OFDM stream. Individual subcarriers, therefore, carry N parallel QAM/PSK streams. In the proposed GOFDM scheme instead, an N-dimensional signal constellation point is transmitted over all N subcarriers simultaneously. When some of the subcarriers are severely affected by channel impairments, the constellation points carried by those subcarriers may be lost in the conventional OFDM. In comparison, under such conditions, the overall signal constellation point will face only small distortion in GOFDM and it can be recovered successfully using the information on the other high fidelity subcarriers. Furthermore, because the channel capacity is a logarithmic function of signal-to-noise ratio but a linear function of the number of dimensions, the spectral efficiency of optical transmission systems can be improved with GOFDM.

  3. Characterizing the Optical Variability of Bright Blazars: Variability-based Selection of Fermi Active Galactic Nuclei

    Science.gov (United States)

    Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Burnett, T. H.; Davenport, James R. A.; Ivezić, Željko; Kochanek, Christopher S.; Plotkin, Richard M.; Sesar, Branimir; Stuart, J. Scott

    2012-11-01

    We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the ~30% of γ-ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability τ, and driving amplitudes on short timescales \\hat{\\sigma }. Imposing cuts on minimum τ and \\hat{\\sigma } allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several-arcminute error ellipses of γ-ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E >= 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r +5238 has optical variability consistent with other γ-ray blazars and is likely to be the γ-ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is ~3 years in the rest frame of the jet, in contrast with the ~320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics.

  4. CHARACTERIZING THE OPTICAL VARIABILITY OF BRIGHT BLAZARS: VARIABILITY-BASED SELECTION OF FERMI ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Ruan, John J.; Anderson, Scott F.; MacLeod, Chelsea L.; Becker, Andrew C.; Davenport, James R. A.; Ivezic, Zeljko [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Burnett, T. H. [Department of Physics, University of Washington, Seattle, WA 98195-1560 (United States); Kochanek, Christopher S. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Plotkin, Richard M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Sesar, Branimir [Division of Physics, Mathematics and Astronomy, Caltech, Pasadena, CA 91125 (United States); Stuart, J. Scott, E-mail: jruan@astro.washington.edu [Lincoln Laboratory, Massachusetts Institute of Technology, 244 Wood Street, Lexington, MA 02420-9108 (United States)

    2012-11-20

    We investigate the use of optical photometric variability to select and identify blazars in large-scale time-domain surveys, in part to aid in the identification of blazar counterparts to the {approx}30% of {gamma}-ray sources in the Fermi 2FGL catalog still lacking reliable associations. Using data from the optical LINEAR asteroid survey, we characterize the optical variability of blazars by fitting a damped random walk model to individual light curves with two main model parameters, the characteristic timescales of variability {tau}, and driving amplitudes on short timescales {sigma}-circumflex. Imposing cuts on minimum {tau} and {sigma}-circumflex allows for blazar selection with high efficiency E and completeness C. To test the efficacy of this approach, we apply this method to optically variable LINEAR objects that fall within the several-arcminute error ellipses of {gamma}-ray sources in the Fermi 2FGL catalog. Despite the extreme stellar contamination at the shallow depth of the LINEAR survey, we are able to recover previously associated optical counterparts to Fermi active galactic nuclei with E {>=} 88% and C = 88% in Fermi 95% confidence error ellipses having semimajor axis r < 8'. We find that the suggested radio counterpart to Fermi source 2FGL J1649.6+5238 has optical variability consistent with other {gamma}-ray blazars and is likely to be the {gamma}-ray source. Our results suggest that the variability of the non-thermal jet emission in blazars is stochastic in nature, with unique variability properties due to the effects of relativistic beaming. After correcting for beaming, we estimate that the characteristic timescale of blazar variability is {approx}3 years in the rest frame of the jet, in contrast with the {approx}320 day disk flux timescale observed in quasars. The variability-based selection method presented will be useful for blazar identification in time-domain optical surveys and is also a probe of jet physics.

  5. Butt-joint integration of active optical components based on InP/AlInGaAsP alloys

    DEFF Research Database (Denmark)

    Kulkova, Irina; Kuznetsova, Nadezda; Semenova, Elizaveta

    2014-01-01

    We demonstrate all-active planar high quality butt-joint (BJ) integration of a QW Semiconductor Optical Amplifier (SOA) and MQW Electro-Absorption Modulator (EAM) based on an InP/AlInGaAsP platform. The degradation of the optical properties in the vicinity of ~1 μm to the BJ interface was determi......We demonstrate all-active planar high quality butt-joint (BJ) integration of a QW Semiconductor Optical Amplifier (SOA) and MQW Electro-Absorption Modulator (EAM) based on an InP/AlInGaAsP platform. The degradation of the optical properties in the vicinity of ~1 μm to the BJ interface...

  6. Optically assisted trapping with high-permittivity dielectric rings: Towards optical aerosol filtration

    CERN Document Server

    Alaee, Rasoul; Rockstuhl, Carsten; Passian, Ali

    2016-01-01

    Controlling the transport, trapping, and filtering of nanoparticles is important for many applications. By virtue of their weak response to gravity and their thermal motion, various physical mechanisms can be exploited for such operations on nanoparticles. However, the manipulation based on optical forces is potentially most appealing since it constitutes a highly deterministic approach. Plasmonic nanostructures have been suggested for this purpose, but they possess the disadvantages of locally generating heat and trapping the nanoparticles directly on surface. Here, we propose the use of dielectric rings made of high permittivity materials for trapping nanoparticles. Thanks to their ability to strongly localize the field in space, nanoparticles can be trapped without contact. We use a semi-analytical method to study the ability of these rings to trap nanoparticles. Results are supported by full-wave simulations. Application of the trapping concept to nanoparticle filtration is suggested.

  7. Changing University Students’ Alternative Conceptions of Optics by Active Learning

    Directory of Open Access Journals (Sweden)

    Zalkida Hadžibegović

    2013-01-01

    Full Text Available Active learning is individual and group participation in effective activities such as in-class observing, writing, experimenting, discussion, solving problems, and talking about to-be-learned topics. Some instructors believe that active learning is impossible, or at least extremely difficult to achieve in large lecture sessions. Nevertheless, the truly impressive implementation results of theSCALE-UP learning environment suggest that such beliefs are false (Beichner et al., 2000. In this study, we present a design of an active learning environment with positive effect on students. The design is based on the following elements: (1 helping students to learn from interactive lecture experiment; (2 guiding students to use justified explanation and prediction after observing and exploring a phenomenon; (3 developing a conceptual question sequencedesigned for use in an interactive lecture with students answering questions in worksheets by writing and drawing; (4 evaluating students’ conceptual change and gains by questions related to light reflection, refraction, and image formation in an exam held a week after the active learning session. Data were collected from 95 science freshmen with different secondary school backgrounds. They participated in geometrical optics classes organized for collecting research results during and after only one active learning session.The results have showed that around 60% of the students changed their initial alternative conceptions of vision and of image formation. It was also found that a large group of university students is likely to be engaged in active learning, shifting from a passive role they usually play during teacher’s lectures.

  8. Read-only high accuracy volume holographic optical correlator

    Science.gov (United States)

    Zhao, Tian; Li, Jingming; Cao, Liangcai; He, Qingsheng; Jin, Guofan

    2011-10-01

    A read-only volume holographic correlator (VHC) is proposed. After the recording of all of the correlation database pages by angular multiplexing, a stand-alone read-only high accuracy VHC will be separated from the VHC recording facilities which include the high-power laser and the angular multiplexing system. The stand-alone VHC has its own low power readout laser and very compact and simple structure. Since there are two lasers that are employed for recording and readout, respectively, the optical alignment tolerance of the laser illumination on the SLM is very sensitive. The twodimensional angular tolerance is analyzed based on the theoretical model of the volume holographic correlator. The experimental demonstration of the proposed read-only VHC is introduced and discussed.

  9. Thermal effects in high average power optical parametric amplifiers.

    Science.gov (United States)

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  10. High-redshift quasar host galaxies with adaptive optics

    CERN Document Server

    Kuhlbrodt, B; Wisotzki, L; Jahnke, K

    2005-01-01

    We present K band adaptive optics observations of three high-redshift (z ~ 2.2) high-luminosity quasars, all of which were studied for the first time. We also bserved several point spread function (PSF) calibrators, non-simultaneously because of the small field of view. The significant temporal PSF variations on timescales of minutes inhibited a straightforward scaled PSF removal from the quasar images. Characterising the degree of PSF concentration by the radii encircling 20% and 80% of the total flux, respectively, we found that even under very different observing conditions the r20 vs. r80 relation varied coherently between individual short exposure images, delineating a well-defined relation for point sources. Placing the quasar images on this relation, we see indications that all three objects were resolved. We designed a procedure to estimate the significance of this result, and to estimate host galaxy parameters, by reproducing the statistical distribution of the individual short exposure images. We fi...

  11. High-speed Integrated Circuits for electrical/Optical Interfaces

    DEFF Research Database (Denmark)

    Jespersen, Christoffer Felix

    2008-01-01

    This thesis is a continuation of the effort to increase the bandwidth of communicationnetworks. The thesis presents the results of the design of several high-speed electrical ircuits for an electrical/optical interface. These circuits have been a contribution to the ESTA project in collaboration ...... as examples. Finally, it is concluded that the VIP-2 process is suitable technology for creating circuits for 100 Gb/s communication networks. Keywords: Indium Phosphide (InP), DHBT, VCO, Colpitt, Static Divider, CDR, PLL, Transceiver...... represents the avant-garde of InP technology, with ft and fmax well above 300 GHz. Principles of high speed design are presented and described as a useful background before proceeding to circuits. A static divider is used as an example to illustrate many of the design principles. Theory and fundamentals...

  12. Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, Kristie L.; Wang, Anbo; Pickrell, Gary R.

    2006-11-14

    This report summarizes technical progress during the program “Optical Fiber High Temperature Sensor Instrumentation for Energy Intensive Industries”, performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The objective of this program was to use technology recently invented at Virginia Tech to develop and demonstrate the application of self-calibrating optical fiber temperature and pressure sensors to several key energy-intensive industries where conventional, commercially available sensors exhibit greatly abbreviated lifetimes due primarily to environmental degradation. A number of significant technologies were developed under this program, including • a laser bonded silica high temperature fiber sensor with a high temperature capability up to 700°C and a frequency response up to 150 kHz, • the world’s smallest fiber Fabry-Perot high temperature pressure sensor (125 x 20 μm) with 700°C capability, • UV-induced intrinsic Fabry-Perot interferometric sensors for distributed measurement, • a single crystal sapphire fiber-based sensor with a temperature capability up to 1600°C. These technologies have been well demonstrated and laboratory tested. Our work plan included conducting major field tests of these technologies at EPRI, Corning, Pratt & Whitney, and Global Energy; field validation of the technology is critical to ensuring its usefulness to U.S. industries. Unfortunately, due to budget cuts, DOE was unable to follow through with its funding commitment to support Energy Efficiency Science Initiative projects and this final phase was eliminated.

  13. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Directory of Open Access Journals (Sweden)

    Heck Martijn J.R.

    2017-01-01

    Full Text Available Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  14. Highly integrated optical phased arrays: photonic integrated circuits for optical beam shaping and beam steering

    Science.gov (United States)

    Heck, Martijn J. R.

    2017-01-01

    Technologies for efficient generation and fast scanning of narrow free-space laser beams find major applications in three-dimensional (3D) imaging and mapping, like Lidar for remote sensing and navigation, and secure free-space optical communications. The ultimate goal for such a system is to reduce its size, weight, and power consumption, so that it can be mounted on, e.g. drones and autonomous cars. Moreover, beam scanning should ideally be done at video frame rates, something that is beyond the capabilities of current opto-mechanical systems. Photonic integrated circuit (PIC) technology holds the promise of achieving low-cost, compact, robust and energy-efficient complex optical systems. PICs integrate, for example, lasers, modulators, detectors, and filters on a single piece of semiconductor, typically silicon or indium phosphide, much like electronic integrated circuits. This technology is maturing fast, driven by high-bandwidth communications applications, and mature fabrication facilities. State-of-the-art commercial PICs integrate hundreds of elements, and the integration of thousands of elements has been shown in the laboratory. Over the last few years, there has been a considerable research effort to integrate beam steering systems on a PIC, and various beam steering demonstrators based on optical phased arrays have been realized. Arrays of up to thousands of coherent emitters, including their phase and amplitude control, have been integrated, and various applications have been explored. In this review paper, I will present an overview of the state of the art of this technology and its opportunities, illustrated by recent breakthroughs.

  15. Design guidelines for high dimensional stability of CFRP optical bench

    Science.gov (United States)

    Desnoyers, Nichola; Boucher, Marc-André; Goyette, Philippe

    2013-09-01

    In carbon fiber reinforced plastic (CFRP) optomechanical structures, particularly when embodying reflective optics, angular stability is critical. Angular stability or warping stability is greatly affected by moisture absorption and thermal gradients. Unfortunately, it is impossible to achieve the perfect laminate and there will always be manufacturing errors in trying to reach a quasi-iso laminate. Some errors, such as those related to the angular position of each ply and the facesheet parallelism (for a bench) can be easily monitored in order to control the stability more adequately. This paper presents warping experiments and finite-element analyses (FEA) obtained from typical optomechanical sandwich structures. Experiments were done using a thermal vacuum chamber to cycle the structures from -40°C to 50°C. Moisture desorption tests were also performed for a number of specific configurations. The selected composite material for the study is the unidirectional prepreg from Tencate M55J/TC410. M55J is a high modulus fiber and TC410 is a new-generation cyanate ester designed for dimensionally stable optical benches. In the studied cases, the main contributors were found to be: the ply angular errors, laminate in-plane parallelism (between 0° ply direction of both facesheets), fiber volume fraction tolerance and joints. Final results show that some tested configurations demonstrated good warping stability. FEA and measurements are in good agreement despite the fact that some defects or fabrication errors remain unpredictable. Design guidelines to maximize the warping stability by taking into account the main dimensional stability contributors, the bench geometry and the optical mount interface are then proposed.

  16. Circular polarization intrinsic optical signal recording of stimulus-evoked neural activity.

    Science.gov (United States)

    Lu, Rong-Wen; Zhang, Qiu-Xiang; Yao, Xin-Cheng

    2011-05-15

    Linear polarization intrinsic optical signal (LP-IOS) measurement can provide sensitive detection of neural activities in stimulus-activated neural tissues. However, the LP-IOS magnitude and signal-to-noise ratio (SNR) are highly correlated with the nerve orientation relative to the polarization plane of the incident light. Because of the complexity of orientation dependency, LP-IOS optimization and outcome interpretation are time consuming and complicated. In this study, we demonstrate the feasibility of circular polarization intrinsic optical signal (CP-IOS) measurement. Our theoretical modeling and experimental investigation indicate that CP-IOS magnitude and SNR are independent from the nerve orientation. Therefore, CP-IOS promises a practical method for polarization IOS imaging of complex neural systems.

  17. All-optical flip-flop operation based on asymmetric active-multimode interferometer bi-stable laser diodes

    DEFF Research Database (Denmark)

    Jiang, H.; Chaen, Y.; Hagio, T.;

    2011-01-01

    We demonstrate fast and low energy all optical flip-flop devices based on asymmetric active-multimode interferometer using high-mesa waveguide structure. The implemented devices showed high speed alloptical flip-flop operation with 25ps long pulses. The rising and falling times of the output sign...

  18. A Miniature Fiber-Optic Sensor for High-Resolution and High-Speed Temperature Sensing in Ocean Environment

    Science.gov (United States)

    2015-11-05

    fiber-optic sensor for high-resolution and high-speed temperature sensing in ocean environment Guigen Liu1, Ming Han1,* Weilin Hou2, Silvia Matt2... sensor performance. In this paper, we present an optical fiber sensor for the high-resolution and high-speed temperature profiling. The developed sensor ...silicon, such as large thermal diffusivity, notable thermo-optic effects and thermal expansion coefficients of silicon, the proposed sensor exhibits

  19. Optical bistability in a high-Q racetrack resonator based on small SU-8 ridge waveguides.

    Science.gov (United States)

    Jin, Li; Fu, Xin; Yang, Bo; Shi, Yaocheng; Dai, Daoxin

    2013-06-15

    A racetrack resonator with a high Q value (~34,000) is demonstrated experimentally based on small SU-8 optical ridge waveguides, which were fabricated with an improved etchless process. Optical bistability is observed in the present racetrack resonator even with a low input optical power (5.6-7.3 mW), which is attributed to the significant thermal nonlinear optical effect due to the high Q value and the large negative thermo-optical coefficient of SU-8. Theoretical modeling for the optical bistability is also given, and it agrees well with the experimental result.

  20. An analogy between optical turbulence and activator-inhibitor dynamics

    CERN Document Server

    Spineanu, F

    2016-01-01

    The propagation of laser beams through madia with cubic nonlinear polarization is part of a wide range of practical applications. The processes that are involved are at the limit of extreme (cuasi-singular) concentration of intensity and the transversal modulational instability, the saturation and defocusing effect of the plasma generated through avalanche and multi-photon (MPI) ionization are competing leading to a complicated pattern of intensity in the transversal plane. This regime has been named \\textquotedblleft optical turbulence\\textquotedblright and it has been studied in experiments and numerical simulations. Led by the similarity of the portraits we have investigated the possibility that the mechanism that underlies the creation of the complex pattern of the intensity field is the manifestation of the dynamics \\textit{activator-inhibitor}. In a previous work we have considered a unique connection, the \\textit{complex Landau-Ginzburg equation}, a common ground for the nonlinear Schrodinger equation ...

  1. Monolithic, High-Speed Fiber-Optic Switching Array for Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This NASA SBIR Phase II effort will develop a 1 x 10 prototype non-mechanical fiber optic switch for use with high power lasers. The proposed optical device is a...

  2. Potassium double tungstate waveguides with high ytterbium concentration for optical amplification

    NARCIS (Netherlands)

    Yong, Yean-Sheng

    2017-01-01

    In this thesis, the research work concerning high ytterbium concentration potassium double tungstate waveguides catered for optical amplification purpose is presented. The scope of the research work includes the investigation of spectroscopic and optical gain properties in epitaxy layers with

  3. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru Miyauchi; Yanjun Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirmlow optical loss and environmental stabilities.

  4. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru; Miyauchi; Yanjun; Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirm low optical loss and environmental stabilities.

  5. High-Frequency RIN Transfer in Fibre Optic Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Kang, Ning

    2011-01-01

    ibre optic parametric amplifiers (FOPAs) are versatile devices for amplification at arbitrary wavelengths, as well as a wide range of optical signal processing applications, including switching, wavelength conversion, regeneration, pulse generation etc [1]. Transfer of intensity fluctuations from...

  6. Performance and production requirements for the optical components in a high-average-power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Chow, R.; Doss, F.W.; Taylor, J.R.; Wong, J.N.

    1999-07-02

    Optical components needed for high-average-power lasers, such as those developed for Atomic Vapor Laser Isotope Separation (AVLIS), require high levels of performance and reliability. Over the past two decades, optical component requirements for this purpose have been optimized and performance and reliability have been demonstrated. Many of the optical components that are exposed to the high power laser light affect the quality of the beam as it is transported through the system. The specifications for these optics are described including a few parameters not previously reported and some component manufacturing and testing experience. Key words: High-average-power laser, coating efficiency, absorption, optical components

  7. High-Performance Optical Frequency References for Space

    Science.gov (United States)

    Schuldt, Thilo; Döringshoff, Klaus; Milke, Alexander; Sanjuan, Josep; Gohlke, Martin; Kovalchuk, Evgeny V.; Gürlebeck, Norman; Peters, Achim; Braxmaier, Claus

    2016-06-01

    A variety of future space missions rely on the availability of high-performance optical clocks with applications in fundamental physics, geoscience, Earth observation and navigation and ranging. Examples are the gravitational wave detector eLISA (evolved Laser Interferometer Space Antenna), the Earth gravity mission NGGM (Next Generation Gravity Mission) and missions, dedicated to tests of Special Relativity, e.g. by performing a Kennedy- Thorndike experiment testing the boost dependence of the speed of light. In this context we developed optical frequency references based on Doppler-free spectroscopy of molecular iodine; compactness and mechanical and thermal stability are main design criteria. With a setup on engineering model (EM) level we demonstrated a frequency stability of about 2·10-14 at an integration time of 1 s and below 6·10-15 at integration times between 100s and 1000s, determined from a beat-note measurement with a cavity stabilized laser where a linear drift was removed from the data. A cavity-based frequency reference with focus on improved long-term frequency stability is currently under development. A specific sixfold thermal shield design based on analytical methods and numerical calculations is presented.

  8. Depth profilometry via multiplexed optical high-coherence interferometry.

    Directory of Open Access Journals (Sweden)

    Farnoud Kazemzadeh

    Full Text Available Depth Profilometry involves the measurement of the depth profile of objects, and has significant potential for various industrial applications that benefit from non-destructive sub-surface profiling such as defect detection, corrosion assessment, and dental assessment to name a few. In this study, we investigate the feasibility of depth profilometry using an Multiplexed Optical High-coherence Interferometry MOHI instrument. The MOHI instrument utilizes the spatial coherence of a laser and the interferometric properties of light to probe the reflectivity as a function of depth of a sample. The axial and lateral resolutions, as well as imaging depth, are decoupled in the MOHI instrument. The MOHI instrument is capable of multiplexing interferometric measurements into 480 one-dimensional interferograms at a location on the sample and is built with axial and lateral resolutions of 40 μm at a maximum imaging depth of 700 μm. Preliminary results, where a piece of sand-blasted aluminum, an NBK7 glass piece, and an optical phantom were successfully probed using the MOHI instrument to produce depth profiles, demonstrate the feasibility of such an instrument for performing depth profilometry.

  9. Thin film detection of High Energy Materials: Optical Pumping Approach

    CERN Document Server

    Barthwal, Sachin

    2014-01-01

    We present our work on High Energy Material detection based on thin film of Lithium using the phenomenon of Optical Pumping. The Li atoms present in the thin film are optically pumped to one of the ground hyperfine energy levels so that they can no more absorb light from the resonant light source. Now in presence of a RF signal, which quantifies the ambient magnetic field, this polarized atomic system is again randomized thus making it reabsorb the resonant light. This gives a quantified measurement of the magnetic field surrounding the thin film detector. This is then mapped to the presence of magnetic HEM and hence the HEM are detected. Our approach in this regard starts with verifying the stability of Lithium atoms in various solvents so as to get a suitable liquid medium to form a thin film. In this regard, various UV-visible characterization spectra are presented to finally approach a stable system for the detection. We have worked on around 10 polar and non- polar solvents to see the stability criteria....

  10. High-speed optical coherence tomography signal processing on GPU

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiqi; Shi Guohua; Zhang Yudong, E-mail: lixiqi@yahoo.cn [Laboratory on Adaptive Optics, Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209 (China)

    2011-01-01

    The signal processing speed of spectral domain optical coherence tomography (SD-OCT) has become a bottleneck in many medical applications. Recently, a time-domain interpolation method was proposed. This method not only gets a better signal-to noise ratio (SNR) but also gets a faster signal processing time for the SD-OCT than the widely used zero-padding interpolation method. Furthermore, the re-sampled data is obtained by convoluting the acquired data and the coefficients in time domain. Thus, a lot of interpolations can be performed concurrently. So, this interpolation method is suitable for parallel computing. An ultra-high optical coherence tomography signal processing can be realized by using graphics processing unit (GPU) with computer unified device architecture (CUDA). This paper will introduce the signal processing steps of SD-OCT on GPU. An experiment is performed to acquire a frame SD-OCT data (400A-linesx2048 pixel per A-line) and real-time processed the data on GPU. The results show that it can be finished in 6.208 milliseconds, which is 37 times faster than that on Central Processing Unit (CPU).

  11. Modulator-Based, High Bandwidth Optical Links for HEP Experiments

    CERN Document Server

    Underwood, D G; Fernando, W S; Stanek, R W

    2012-01-01

    As a concern with the reliability, bandwidth and mass of future optical links in LHC experiments, we are investigating CW lasers and light modulators as an alternative to VCSELs. These links will be particularly useful if they utilize light modulators which are very small, low power, high bandwidth, and are very radiation hard. We have constructed a test system with 3 such links, each operating at 10 Gb/s. We present the quality of these links (jitter, rise and fall time, BER) and eye mask margins (10GbE) for 3 different types of modulators: LiNbO3-based, InP-based, and Si-based. We present the results of radiation hardness measurements with up to ~1012 protons/cm2 and ~65 krad total ionizing dose (TID), confirming no single event effects (SEE) at 10 Gb/s with either of the 3 types of modulators. These optical links will be an integral part of intelligent tracking systems at various scales from coupled sensors through intra-module and off detector communication. We have used a Si-based photonic transceiver to...

  12. Optical polarization of high-energy BL Lac objects

    CERN Document Server

    Hovatta, T; Blinov, D; Pavlidou, V; Nilsson, K; Kiehlmann, S; Angelakis, E; Ramazani, V Fallah; Liodakis, I; Myserlis, I; Panopoulou, G V; Pursimo, T

    2016-01-01

    We investigate the optical polarization properties of high-energy BL Lac objects using data from the RoboPol blazar monitoring program and the Nordic Optical Telescope. We wish to understand if there are differences in the BL Lac objects that are detected with the current-generation TeV instruments compared to those that have not yet been detected. The mean polarization fraction of the TeV-detected BL Lacs is 5% while the non-TeV sources show a higher mean polarization fraction of 7%. This difference in polarization fraction disappears when the dilution by the unpolarized light of the host galaxy is accounted for. The TeV sources show somewhat lower fractional polarization variability amplitudes than the non-TeV sources. Also the fraction of sources with a smaller spread in the Q/I - U/I -plane and a clumped distribution of points away from the origin, possibly indicating a preferred polarization angle, is larger in the TeV than in the non-TeV sources. These differences between TeV and non-TeV samples seems t...

  13. HIGH-STABLE ERBIUM SUPERLUMINESCENT FIBER OPTICAL SOURCES CREATION METHODS

    OpenAIRE

    A. S. Aleynik; N. E. Kikilich; V. N. Kozlov; A. A. Vlasov; NIKITENKO A.N.

    2016-01-01

    We present the overview of wideband Erbium doped superluminescent fiber sources (EDSFS) creation methods. This type of optical sources is mainly used in navigation accuracy class fiber-optical gyroscopes (FOG) production. For this application an optical source should have small coherence length to reduce FOG output signal error rate. Output signal errors are caused by different parasitic effects: reverse Rayleigh scattering, optical components mode swapping, Kerr effect. Consequently, the mos...

  14. Fiber-Optical Parametric Amplification of Sub-Picosecond Pulses for High-Speed Optical Communications

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Cristofori, Valentina; Rottwitt, Karsten

    2015-01-01

    This article reviews recent results of amplification of short optical pulses using fiber-optical parametric amplifiers. This includes chirped-pulse amplification of 400 fs pulses, error-free amplification of a 640-Gbit/s optical time-division multiplexed signal with less than a 1-dB power penalty...

  15. Vibration active control of smart structures incorporating ER actuators and fiber optic vibration sensors based on speckle detection

    Science.gov (United States)

    Leng, Jinsong; Asundi, Anand K.

    1999-06-01

    A smart structures system based on the fiber optic sensors and ER fluids actuators have been developed to used active vibration control in this paper. There are many advantages of this optical sensor such as high accurate, simple construction and low cost. A method of sensing vibration using the detection of changes in the spatial distribution of energy in the output of a multi-mode optic fiber has been demonstrated. A multi-mode optical fiber whose diameter is 200/230 micrometers is used in the present experiment. A multi- mode optical fiber vibration sensor based on the detection of the spatial speckle has been made. The experimental test have been finished. It has been found that this fiber optic sensor has higher sensitivity and better dynamic and static properties. At the meantime, the electrorheological (ER) fluids have been used as actuator to vibration control because of it's fast strong reversible change of the rheological properties under external electric field. A smart composite beam embedded ER fluids and fiber optic vibration sensor have been made in this paper. Finally, the experiment of structural vibration active control of smart structure incorporating the ER fluids and fiber optic vibration sensor have been finished.

  16. Ultrafast optical switching of infrared plasmon polaritons in high-mobility graphene

    Science.gov (United States)

    Ni, G. X.; Wang, L.; Goldflam, M. D.; Wagner, M.; Fei, Z.; McLeod, A. S.; Liu, M. K.; Keilmann, F.; Özyilmaz, B.; Castro Neto, A. H.; Hone, J.; Fogler, M. M.; Basov, D. N.

    2016-04-01

    The success of metal-based plasmonics for manipulating light at the nanoscale has been empowered by imaginative designs and advanced nano-fabrication. However, the fundamental optical and electronic properties of elemental metals, the prevailing plasmonic media, are difficult to alter using external stimuli. This limitation is particularly restrictive in applications that require modification of the plasmonic response at sub-picosecond timescales. This handicap has prompted the search for alternative plasmonic media, with graphene emerging as one of the most capable candidates for infrared wavelengths. Here we visualize and elucidate the properties of non-equilibrium photo-induced plasmons in a high-mobility graphene monolayer. We activate plasmons with femtosecond optical pulses in a specimen of graphene that otherwise lacks infrared plasmonic response at equilibrium. In combination with static nano-imaging results on plasmon propagation, our infrared pump-probe nano-spectroscopy investigation reveals new aspects of carrier relaxation in heterostructures based on high-purity graphene.

  17. Optically powered active sensing system for Internet Of Things

    Science.gov (United States)

    Gao, Chen; Wang, Jin; Yin, Long; Yang, Jing; Jiang, Jian; Wan, Hongdan

    2014-10-01

    Internet Of Things (IOT) drives a significant increase in the extent and type of sensing technology and equipment. Sensors, instrumentation, control electronics, data logging and transmission units comprising such sensing systems will all require to be powered. Conventionally, electrical powering is supplied by batteries or/and electric power cables. The power supply by batteries usually has a limited lifetime, while the electric power cables are susceptible to electromagnetic interference. In fact, the electromagnetic interference is the key issue limiting the power supply in the strong electromagnetic radiation area and other extreme environments. The novel alternative method of power supply is power over fiber (PoF) technique. As fibers are used as power supply lines instead, the delivery of the power is inherently immune to electromagnetic radiation, and avoids cumbersome shielding of power lines. Such a safer power supply mode would be a promising candidate for applications in IOT. In this work, we built up optically powered active sensing system, supplying uninterrupted power for the remote active sensors and communication modules. Also, we proposed a novel maximum power point tracking technique for photovoltaic power convertors. In our system, the actual output efficiency greater than 40% within 1W laser power. After 1km fiber transmission and opto-electric power conversion, a stable electric power of 210mW was obtained, which is sufficient for operating an active sensing system.

  18. High lightning activity in maritime clouds near Mexico

    Directory of Open Access Journals (Sweden)

    B. Kucienska

    2012-01-01

    Full Text Available Lightning activity detected by the World Wide Lightning Location Network (WWLLN over oceanic regions adjacent to Mexico is often as high as that observed over the continent. In order to explore the possible cause of the observed high flash density over those regions, the relationships between lightning, rainfall, vertical hydrometeor profiles, latent heating, wind variability and aerosol optical thickness are analyzed. The characteristics of lightning and precipitation over four oceanic zones adjacent to Mexican coastlines are contrasted against those over the continent. In addition, we compare two smaller regions over the Tropical Pacific Ocean: one located within the Inter-Tropical Converge Zone and characterized by high rainfall and weak lightning activity and the other influenced by a continental jet and presenting high rainfall and strong lightning activity over the Gulf of Tehuantepec. Maritime precipitating clouds that develop within the region influenced by offshore winds exhibit similar properties to continental clouds: large content of precipitation ice and an increased height range of coexistence of precipitation ice and cloud water. During the rainy season, monthly distribution of lightning within the region influenced by the continental jet is contrary to that of rainfall. Moreover, the monthly variability of lightning is very similar to the variability of the meridional wind component and it is also related to the variability of aerosol optical depth. The analysis strongly suggests that the high lightning activity observed over the Gulf of Tehuantepec is caused by continental cloud condensation nuclei advected over the ocean.

  19. High-Speed Electro-Optic Modulator Integrated with Graphene-Boron Nitride Heterostructure and Photonic Crystal Nanocavity

    CERN Document Server

    Gao, Yuanda; Gan, Xuetao; Li, Luozhou; Peng, Cheng; Meric, Inanc; Wang, Lei; Szep, Attila; Walker, Dennis; Hone, James; Englund, Dirk

    2014-01-01

    Nanoscale and power-efficient electro-optic (EO) modulators are essential components for optical interconnects that are beginning to replace electrical wiring for intra- and inter-chip communications. Silicon-based EO modulators show sufficient figures of merits regarding device footprint, speed, power consumption and modulation depth. However, the weak electro-optic effect of silicon still sets a technical bottleneck for these devices, motivating the development of modulators based on new materials. Graphene, a two-dimensional carbon allotrope, has emerged as an alternative active material for optoelectronic applications owing to its exceptional optical and electronic properties. Here, we demonstrate a high-speed graphene electro-optic modulator based on a graphene-boron nitride (BN) heterostructure integrated with a silicon photonic crystal nanocavity. Strongly enhanced light-matter interaction of graphene in a submicron cavity enables efficient electrical tuning of the cavity reflection. We observe a modul...

  20. 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.

  1. Towards highly multimode optical quantum memory for quantum repeaters

    CERN Document Server

    Jobez, Pierre; Laplane, Cyril; Etesse, Jean; Ferrier, Alban; Goldner, Philippe; Gisin, Nicolas; Afzelius, Mikael

    2015-01-01

    Long-distance quantum communication through optical fibers is currently limited to a few hundreds of kilometres due to fiber losses. Quantum repeaters could extend this limit to continental distances. Most approaches to quantum repeaters require highly multimode quantum memories in order to reach high communication rates. The atomic frequency comb memory scheme can in principle achieve high temporal multimode storage, without sacrificing memory efficiency. However, previous demonstrations have been hampered by the difficulty of creating high-resolution atomic combs, which reduces the efficiency for multimode storage. In this article we present a comb preparation method that allows one to increase the multimode capacity for a fixed memory bandwidth. We apply the method to a $^{151}$Eu$^{3+}$-doped Y$_2$SiO$_5$ crystal, in which we demonstrate storage of 100 modes for 51 $\\mu$s using the AFC echo scheme (a delay-line memory), and storage of 50 modes for 0.541 ms using the AFC spin-wave memory (an on-demand memo...

  2. Optical interconnection networks for high-performance computing systems.

    Science.gov (United States)

    Biberman, Aleksandr; Bergman, Keren

    2012-04-01

    Enabled by silicon photonic technology, optical interconnection networks have the potential to be a key disruptive technology in computing and communication industries. The enduring pursuit of performance gains in computing, combined with stringent power constraints, has fostered the ever-growing computational parallelism associated with chip multiprocessors, memory systems, high-performance computing systems and data centers. Sustaining these parallelism growths introduces unique challenges for on- and off-chip communications, shifting the focus toward novel and fundamentally different communication approaches. Chip-scale photonic interconnection networks, enabled by high-performance silicon photonic devices, offer unprecedented bandwidth scalability with reduced power consumption. We demonstrate that the silicon photonic platforms have already produced all the high-performance photonic devices required to realize these types of networks. Through extensive empirical characterization in much of our work, we demonstrate such feasibility of waveguides, modulators, switches and photodetectors. We also demonstrate systems that simultaneously combine many functionalities to achieve more complex building blocks. We propose novel silicon photonic devices, subsystems, network topologies and architectures to enable unprecedented performance of these photonic interconnection networks. Furthermore, the advantages of photonic interconnection networks extend far beyond the chip, offering advanced communication environments for memory systems, high-performance computing systems, and data centers.

  3. Epidermal segmentation in high-definition optical coherence tomography.

    Science.gov (United States)

    Li, Annan; Cheng, Jun; Yow, Ai Ping; Wall, Carolin; Wong, Damon Wing Kee; Tey, Hong Liang; Liu, Jiang

    2015-01-01

    Epidermis segmentation is a crucial step in many dermatological applications. Recently, high-definition optical coherence tomography (HD-OCT) has been developed and applied to imaging subsurface skin tissues. In this paper, a novel epidermis segmentation method using HD-OCT is proposed in which the epidermis is segmented by 3 steps: the weighted least square-based pre-processing, the graph-based skin surface detection and the local integral projection-based dermal-epidermal junction detection respectively. Using a dataset of five 3D volumes, we found that this method correlates well with the conventional method of manually marking out the epidermis. This method can therefore serve to effectively and rapidly delineate the epidermis for study and clinical management of skin diseases.

  4. High Sensitivity Polymer Optical Fiber-Bragg-Grating-Based Accelerometer

    DEFF Research Database (Denmark)

    Stefani, Alessio; Andresen, Søren; Yuan, Wu

    2012-01-01

    We report on the fabrication and characterization of the first accelerometer based on a polymer optical fiber Bragg grating (FBG) for operation at both 850 and 1550 nm. The devices have a flat frequency response over a 1-kHz bandwidth and a resonance frequency of about 3 kHz. The response is linear...... up to at least 15 g and sensitivities as high as 19 pm/g (shift in resonance wavelength per unit acceleration) have been demonstrated. Given that 15 g corresponds to a strain of less than 0.02% and that polymer fibers have an elastic limit of more than 1%, the polymer FBG accelerometer can measure...... very strong accelerations. We compare with corresponding silica FBG accelerometers and demonstrate that using polymer FBGs improves the sensitivity by more than a factor of four and increases the figure of merit, defined as the sensitivity times the resonance frequency squared....

  5. Highly sensitive optical sensor system for blood leakage detection

    Science.gov (United States)

    Ueda, Masahiro; Ishikawa, Kazuhiko; Jie, Chen; Sanae, Mizuno; Touma, Yasunori

    A highly sensitive method for the detection of blood leakage has been developed, and a practical sensor system for blood concentration measurement has been constructed. The present method is based on the attenuation of laser light by blood cells. The effects of the fluctuations of the incident laser light power are eliminated by normalizing the attenuated light intensity by the incident light intensity. A part of the incident laser light is reflected by a beam splitter mounted at the entrance of the test cell, of which the power is measured to provide base data for normalization. The optical path is extended to enhance sensitivity by using a pair of side mirrors. This multi-reflection method is very effective to increase sensitivity; the maximum sensitivity obtained for blood concentration is about 4 X 10 -6 by volume, which is significantly higher than that of the conventional sensors.

  6. Review of High-Speed Fiber Optic Grating Sensors Systems

    Energy Technology Data Exchange (ETDEWEB)

    Udd, E; Benterou, J; May, C; Mihailov, S J; Lu, P

    2010-03-24

    Fiber grating sensors can be used to support a wide variety of high speed measurement applications. This includes measurements of vibrations on bridges, traffic monitoring on freeways, ultrasonic detection to support non-destructive tests on metal plates and providing details of detonation events. This paper provides a brief overview of some of the techniques that have been used to support high speed measurements using fiber grating sensors over frequency ranges from 10s of kHz, to MHZ and finally toward frequencies approaching the GHz regime. Very early in the development of fiber grating sensor systems it was realized that a high speed fiber grating sensor system could be realized by placing an optical filter that might be a fiber grating in front of a detector so that spectral changes in the reflection from a fiber grating were amplitude modulated. In principal the only limitation on this type of system involved the speed of the output detector which with the development of high speed communication links moved from the regime of 10s of MHz toward 10s of GHz. The earliest deployed systems involved civil structures including measurements of the strain fields on composite utility poles and missile bodies during break tests, bridges and freeways. This was followed by a series of developments that included high speed fiber grating sensors to support nondestructive testing via ultrasonic wave detection, high speed machining and monitoring ship hulls. Each of these applications involved monitoring mechanical motion of structures and thus interest was in speeds up to a few 10s of MHz. Most recently there has been interest in using fiber grating to monitor the very high speed events such as detonations and this has led to utilization of fiber gratings that are consumed during an event that may require detection speeds of hundreds of MHz and in the future multiple GHz.

  7. Flood mapping by combining the strengths of optical and Sentinel active radar remote sensing

    Science.gov (United States)

    Winsemius, H. C.; Brakenridge, G. R.; Westerhoff, R.; Huizinga, J.; Villars, N.; Bishop, C.

    2012-04-01

    Flood mapping with remote sensing plays an important role in large scale disaster management procedures. For this purpose, the Dartmouth Flood Observatory (DFO) gained experience since 1993 with the production of flood maps from optical satellite imagery and has currently established, together with NASA collaborators, a fully automated, global, near real-time service. Another consortium is also presently working on an automated, near real-time, global flood mapping procedure called the 'Global Flood Observatory' (GFO), which will make use of high resolution Sentinel data. The procedure is currently tested on Envisat active radar (ASAR) imagery. Both the DFO and GFO projects provide open data output of their data and maps. The optical and radar approaches to flood mapping each have advantages and suffer from shortcomings. Optical remote sensing via the U.S. MODIS and VIIRS sensors is constrained by cloud cover but can attain a high revisit frequency (>2 /day), whereas the Envisat ASAR is not affected by cloud cover, but uses a lower revisit frequency (generally once/3 days, depending on the location). In this contribution, we demonstrate the combination of both approaches into one flood mapping result. This results in improved flood mapping in a case study over the Chao Phraya basin (Bangkok surroundings) during the recent October-November 2011 extreme flooding. The combined map shows that during overpass, ASAR reveals flooded regions over cloud-obscured areas, which clearly follow elevated features in the landscape such as roads, embankments and railways. Meanwhile, the high frequency of delivery of the optical information ensures timely information. Also, the quite different water classification methods used for the optical and ASAR data sources show good agreement and have been successfully merged into one GIS data product. This can also be automatically generated and disseminated on a global basis.

  8. Choroidal thinning in high myopia measured by optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Ikuno Y

    2013-05-01

    Full Text Available Yasushi Ikuno, Satoko Fujimoto, Yukari Jo, Tomoko Asai, Kohji NishidaDepartment of Ophthalmology, Osaka University Graduate School of Medicine, Osaka, JapanPurpose: To investigate the rate of choroidal thinning in highly myopic eyes.Patients and methods: A retrospective observational study of 37 eyes of 26 subjects (nine males and 17 females, mean age 39.6 ± 7.7 years with high myopia but no pathologies who had undergone spectral domain optical coherence tomography and repeated the test 1 year later (1 ± 0.25 year at Osaka University Hospital, Osaka, Japan. Patients older than 50 years with visual acuity worse than 20/40 or with whitish chorioretinal atrophy involving the macula were excluded. Two masked raters measured the choroidal thicknesses (CTs at the foveda, 3 mm superiorly, inferiorly, temporally, and nasally on the images and averaged the values. The second examination was about 365 days after the baseline examination. The CT reduction per year (CTRPY was defined as (CT 1 year after - baseline CT/days between the two examinations × 365. The retinal thicknesses were also investigated.Results: The CTRPY at the fovea was −1.0 ± 22.0 µm (range –50.2 to 98.5 at the fovea, –6.5 ± 24.3 µm (range −65.8 to 90.2 temporally, –0.5 ± 22.3 µm (range –27.1 to 82.5 nasally, –9.7 ± 21.7 µm (range –40.1 to 60.1 superiorly, and –1.4 ± 25.5 µm (range –85.6 to 75.2 inferiorly. There were no significant differences in the CTRPY at each location (P = 0.34. The CT decreased significantly (P < 0.05 only superiorly. The superior CTRPY was negatively correlated with the axial length (P < 0.05. The retinal thickness at the fovea did not change. Stepwise analysis for CTRPY selected axial length (P = 0.04, R2 = 0.13 and age (P = 0.08, R2 = 0.21 as relevant factors.Conclusions: The highly myopic choroid might gradually thin and be affected by many factors. Location and axial length are key factors to regulate the rate of choroidal

  9. A highly efficient thermo-optic microring modulator assisted by graphene

    Science.gov (United States)

    Gan, Sheng; Cheng, Chuantong; Zhan, Yaohui; Huang, Beiju; Gan, Xuetao; Li, Shaojuan; Lin, Shenghuang; Li, Xiaofeng; Zhao, Jianlin; Chen, Hongda; Bao, Qiaoliang

    2015-11-01

    Graphene's remarkable electrical and optical properties afford great potential for constructing various optoelectronic devices, including modulators, photodetectors and pulse lasers. In particular, graphene-based optical modulators were demonstrated to be featured with a broadband response, small footprint, ultrafast speed and CMOS-compatibility, which may provide an alternative architecture for light-modulation in integrated photonic circuits. While on-chip graphene modulators have been studied in various structures, most of them are based on a capacitance-like configuration subjected to complicated fabrication processes and providing a low yield of working devices. Here, we experimentally demonstrate a new type of graphene modulator by employing graphene's electrical and thermal properties, which can be achieved with a simple fabrication flow. On a graphene-coated microring resonator with a small active area of 10 μm2, we have obtained an effective optical modulation via thermal energy electrically generated in a graphene layer. The resonant wavelength of the ring resonator shifts by 2.9 nm under an electrical power of 28 mW, which enables a large modulation depth of 7 dB and a broad operating wavelength range of 6.2 nm with 3 dB modulation. Due to the extremely high electrical and thermal conductivity in graphene, the graphene thermo-optical modulator operates at a very fast switching rate compared with the conventional silicon thermo-optic modulator, i.e. 10%-90% rise (90%-10% fall) time of 750 ns (800 ns). The results promise a novel architecture for massive on-chip modulation of optical interconnects compatible with CMOS technology.

  10. Adapting an optical nanoantenna for high E-field probing applications to a waveguided optical waveguide (WOW)

    DEFF Research Database (Denmark)

    Rindorf, Lars Henning; Glückstad, Jesper

    2013-01-01

    light wavelength while admitting other wavelengths of light which address certain functionalities, e.g. drug release, in the WOW. In particular, we study a bow-tie optical nano-antenna to circular dielectric waveguides in aqueous environments. It is shown with finite element computer simulations......In the current work we intend to use the optical nano-antenna to include various functionalities for the recently demonstrated waveguided optical waveguide (WOW) by Palima et al. (Optics Express 2012). Specifically, we intend to study a WOW with an optical nano-antenna which can block the guiding...... that the nanoantenna can be made to operate in a bandstop mode around its resonant wavelength where there is a very high evanescent strong electrical probing field close to the antennas, and additionally the fluorescence or Raman excitations will be be unpolluted by stray light from the WOW due to the band...

  11. High contrast all-optical diode based on direction-dependent optical bistability within asymmetric ring cavity

    Science.gov (United States)

    Xia, Xiu-Wen; Zhang, Xin-Qin; Xu, Jing-Ping; Yang, Ya-Ping

    2016-08-01

    We propose a simple all-optical diode which is comprised of an asymmetric ring cavity containing a two-level atomic ensemble. Attributed to spatial symmetry breaking of the ring cavity, direction-dependent optical bistability is obtained in a classical bistable system. Therefore, a giant optical non-reciprocity is generated, which guarantees an all-optical diode with a high contrast up to 22 dB. Furthermore, its application as an all-optical logic AND gate is also discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274242, 11474221, and 11574229), the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. U1330203), and the National Key Basic Research Special Foundation of China (Grant Nos. 2011CB922203 and 2013CB632701).

  12. Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

    KAUST Repository

    Li, Yuan

    2014-12-03

    We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

  13. A surface-enhanced Raman scattering (SERS-active optical fiber sensor based on a three-dimensional sensing layer

    Directory of Open Access Journals (Sweden)

    Chunyu Liu

    2014-08-01

    Full Text Available To fabricate a new surface-enhanced Raman scattering (SERS-active optical fiber sensor, the design and preparation of SERS-active sensing layer is one of important topics. In this study, we fabricated a highly sensitive three-dimensional (3D SERS-active sensing layer on the optical fiber terminal via in situ polymerizing a porous polymer material on a flat optical fiber terminal through thermal-induced process, following with the photochemical silver nanoparticles growth. The polymerized polymer formed a 3D porous structure with the pore size of 0.29–0.81 μm, which were afterward decorated with abundant silver nanoparticles with the size of about 100 nm, allowing for higher SERS enhancement. This SERS-active optical fiber sensor was applied for the determination of 4-mercaptopyridine, crystal violet and maleic acid The enhancement factor of this SERS sensing layer can be reached as about 108. The optical fiber sensor with high sensitive SERS-active porous polymer is expected for online analysis and environment detection.

  14. High speed, high power one-dimensional beam steering from a 6-element optical phased array.

    Science.gov (United States)

    Huang, W Ronny; Montoya, Juan; Kansky, Jan E; Redmond, Shawn M; Turner, George W; Sanchez-Rubio, Antonio

    2012-07-30

    Beam steering at high speed and high power is demonstrated from a 6-element optical phased array using coherent beam combining (CBC) techniques. The steering speed, defined as the inverse of the time to required to sweep the beam across the steering range, is 40 MHz and the total power is 396 mW. The measured central lobe FWHM width is 565 μrad. High on-axis intensity is maintained periodically by phase-locking the array via a stochastic-parallel-gradient-descent (SPGD) algorithm. A master-oscillator-power-amplifier (MOPA) configuration is used where the amplifier array elements are semiconductor slab-coupled-optical-waveguide-amplifiers (SCOWAs). The beam steering is achieved by LiNbO(3) phase modulators; the phase-locking occurs by current adjustment of the SCOWAs. The system can be readily scaled to GHz steering speed and multiwatt-class output.

  15. High lightning activity in maritime clouds near Mexico

    Science.gov (United States)

    Kucienska, B.; Raga, G. B.; Romero-Centeno, R.

    2012-09-01

    Lightning activity detected by the World Wide Lightning Location Network (WWLLN) over oceanic regions adjacent to Mexico is often as high as that observed over the continent. In order to explore the possible causes of the observed high flash density over those regions, the relationships between lightning, rainfall, vertical hydrometeor profiles, latent heating, wind variability and aerosol optical depth are analyzed. The characteristics of lightning and precipitation over four oceanic zones adjacent to Mexican coastlines are contrasted against those over the continent. The number of flashes per rainfall over some coastal maritime regions is found to be higher than over the continent. The largest number of flashes per rainfall is observed during the biomass burning season. In addition, we compare two smaller areas of the Tropical Pacific Ocean: one located within the Inter-Tropical Convergence Zone and characterized by high rainfall and weak lightning activity and the other one influenced by a continental wind jet and characterized by high rainfall and strong lightning activity. During the rainy season, the monthly distribution of lightning within the region influenced by the continental wind jet is contrary to that of rainfall. Moreover, the monthly variability of lightning is very similar to the variability of the meridional wind component and it is also related to the variability of aerosol optical depth. The analysis suggests that the high lightning activity observed over coastal Pacific region is linked to the continental cloud condensation nuclei advected over the ocean. Analysis of daily observations indicates that the greatest lightning density is observed for moderate values of the aerosol optical depth, between 0.2 and 0.35.

  16. High pressure optical studies of crystalline anils and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Hockert, E.N.; Drickamer, H.G.

    1977-12-01

    High pressure optical studies have been made on a series of crystalline therochromic and photochromic anils and model compounds. Measurements include absorption and emission peak locations and the integrated intensities of various absorption peaks including the uv peak and visible peaks introduced thermally or by irradiation at various temperatures and pressures. Emission yields were also obtained. For the thermochromic compounds there was a large increase in the equilibrium yield of the thermally induced peak with pressure (piezochromism), corresponding to a volume decrease of approx.1.2 cc/mole for 5-bromosalicylidene aniline (5BrSA). The emission peak shifts to lower energy and decreases in intensity primarily because of increased rate of the radiationless conversion. For salicylidene aniline and related photochromic crystals the rate of photochromic conversion varied with both pressure and temperature in a manner which depends on the size of the energy barriers to the forward and reverse processes. The emission yield increases with pressure at low pressure, goes through a maximum, and decreases at high pressure. At low pressure the dominant feature is increase in occupation of the emitting state while at high pressure the increased rate of the radiationless process governs. For 2- (O-hydroxyphenyl) benzoxazole (OHBO) (see Fig. 1), where a keto--enol rearrangement is most probable, the changes in absorption and emission intensity can be related to the same diagram used for the anils. This diagram also describes the behavior of benzilidene aniline (BA), where only a cis--trans isomerization is possible.

  17. High-contrast self-imaging with ordered optical elements

    CERN Document Server

    Naqavi, Ali; Rossi, Markus

    2016-01-01

    Creating arbitrary light patterns finds applications in various domains including lithography, beam shaping, metrology, sensing and imaging. We study the formation of high-contrast light patterns that are obtained by transmission through an ordered optical element based on self-imaging.By applying the phase-space method, we explain phenomena such as the Talbot and the angular Talbot effects. We show that the image contrast is maximum when the source is either a plane wave or a point source, and it has a minimum for a source with finite spatial extent. We compare these regimes and address some of their fundamental differences. Specifically, we prove that increasing the source divergence reduces the contrast for the plane wave illumination but increases it for the point source. Also, we show that to achieve high contrast with a point source, tuning the source size and its distance to the element is crucial.We furthermore indicate and explore the possibility of realizing highly complex light patterns by using a ...

  18. High speed optical wireless data transmission system for particle sensors in high energy physics

    Science.gov (United States)

    Ali, W.; Corsini, R.; Ciaramella, E.; Dell'Orso, R.; Messineo, A.; Palla, F.

    2015-08-01

    High speed optical fiber or copper wire communication systems are frequently deployed for readout data links used in particle physics detectors. Future detector upgrades will need more bandwidth for data transfer, but routing requirements for new cables or optical fiber will be challenging due to space limitations. Optical wireless communication (OWC) can provide high bandwidth connectivity with an advantage of reduced material budget and complexity of cable installation and management. In a collaborative effort, Scuola Superiore Sant'Anna and INFN Pisa are pursuing the development of a free-space optical link that could be installed in a future particle physics detector or upgrade. We describe initial studies of an OWC link using the inner tracker of the Compact Muon Solenoid (CMS) detector as a reference architecture. The results of two experiments are described: the first to verify that the laser source transmission wavelength of 1550 nm will not introduce fake signals in silicon strip sensors while the second was to study the source beam diameter and its tolerance to misalignment. For data rates of 2.5 Gb/s and 10 Gb/s over a 10 cm working distance it was observed that a tolerance limit of ±0.25 mm to ±0.8 mm can be obtained for misaligned systems with source beam diameters of 0.38 mm to 3.5 mm, respectively.

  19. Large-aperture, high-damage-threshold optics for beamlet

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, J.H.; Atherton, L.J.; DeYoreo, J.J. [and others

    1996-06-01

    Beamlet serves as a test bed for the proposed National Ignition Facility (NIF) laser design and components. Therefore, its optics are similar in size and quality to those proposed for the NIF. In general, the optics in the main laser cavity and transport section of Beamlet are larger and have higher damage thresholds than the optics manufactured for any of the previous laser systems. In addition, the quality of the Beamlet optical materials is higher, leading to better wavefront quality, higher optical transmission, and lower-intensity modulation of the output laser beam than, for example, that typically achieved on Nova. In this article, the authors discuss the properties and characteristics of the large-aperture optics used on Beamlet.

  20. Advanced Modulation Techniques for High-Performance Computing Optical Interconnects

    DEFF Research Database (Denmark)

    Karinou, Fotini; Borkowski, Robert; Zibar, Darko

    2013-01-01

    We experimentally assess the performance of a 64 × 64 optical switch fabric used for ns-speed optical cell switching in supercomputer optical interconnects. More specifically, we study four alternative modulation formats and detection schemes, namely, 10-Gb/s nonreturn-to-zero differential phase......-shift keying with balanced direct detection, 10-Gb/s polarization division multiplexed (PDM) quadrature phase-shift keying, 40-Gb/s single-polarization 16-ary quadrature amplitude modulation (16QAM), and 80-Gb/s PDM-16QAM, with coherent intradyne detection, in conjunction with an optimized version...... of the optical shared memory supercomputer interconnect system switch fabric. In particular, we investigate the resilience of the aforementioned advanced modulation formats to the nonlinearities of semiconductor optical amplifiers, used as ON/OFF gates in the supercomputer optical switch fabric under study...

  1. High-dynamic-range rf fiber optic link for passive antenna remoting

    Science.gov (United States)

    LaGasse, Michael J.; Thaniyavarn, Suwat

    1996-11-01

    This paper describes a bias-free, high-dynamic range, phase- modulated fiber optic link. An optical delay line filter is used for both phase demodulation and optical carrier suppression. A spur free dynamic range of 114 dB-Hz2/3 is experimentally demonstrated at a frequency of 12.5 GHz.

  2. Optical Amplication for Terabit-per-Second Ultra-High Speed Communication Systems

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh

    The present thesis is concerned with fiber optical parametric amplification and regeneration for high-speed optical communication systems. Fiber optical parametric amplifiers (FOPAs) have multi-functional applications depending on their implementation in optical systems. Based on a few femtosecond...... amplification response time and flexible operation spectral range, FOPAs are able to simultaneously operate as amplifiers and all-optical signal processors in high-speed Tbaud networks. In this thesis, we study the performance of FOPAs in detail in the linear and nonlinear (saturated) regimes where they can...... be utilized as all-optical regenerators. The optical gain and amplitude regeneration properties of FOPAs are investigated for monochromatic waves, short optical pulses and data modulated signals up to 640 Gbit/s. In the fundamental study part of the thesis, an original physical explanation behind an observed...

  3. (HEL MRI) 3D Meta Optics for High Energy Lasers

    Science.gov (United States)

    2016-09-13

    optical communication link using orbital angular momentum multiplexing ." Optics express 24, no. 9 (2016): 9794-9805. 3. Li, Yuan, Wenzhe Li, J. Miller, and...Magnusson, R.; Binun, P.; McCormick, K., "Wavelength Selection and Polarization Multiplexing of Blue Laser Diodes," in Photonics Technology Letters, IEEE...spatial multiplexing can take advantage of a non-Gaussian beam profile. If the components are to be used as out-couplers in bulk lasers , the optics

  4. High-Throughput Analysis of Enzyme Activities

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Guoxin [Iowa State Univ., Ames, IA (United States)

    2007-01-01

    High-throughput screening (HTS) techniques have been applied to many research fields nowadays. Robot microarray printing technique and automation microtiter handling technique allows HTS performing in both heterogeneous and homogeneous formats, with minimal sample required for each assay element. In this dissertation, new HTS techniques for enzyme activity analysis were developed. First, patterns of immobilized enzyme on nylon screen were detected by multiplexed capillary system. The imaging resolution is limited by the outer diameter of the capillaries. In order to get finer images, capillaries with smaller outer diameters can be used to form the imaging probe. Application of capillary electrophoresis allows separation of the product from the substrate in the reaction mixture, so that the product doesn't have to have different optical properties with the substrate. UV absorption detection allows almost universal detection for organic molecules. Thus, no modifications of either the substrate or the product molecules are necessary. This technique has the potential to be used in screening of local distribution variations of specific bio-molecules in a tissue or in screening of multiple immobilized catalysts. Another high-throughput screening technique is developed by directly monitoring the light intensity of the immobilized-catalyst surface using a scientific charge-coupled device (CCD). Briefly, the surface of enzyme microarray is focused onto a scientific CCD using an objective lens. By carefully choosing the detection wavelength, generation of product on an enzyme spot can be seen by the CCD. Analyzing the light intensity change over time on an enzyme spot can give information of reaction rate. The same microarray can be used for many times. Thus, high-throughput kinetic studies of hundreds of catalytic reactions are made possible. At last, we studied the fluorescence emission spectra of ADP and obtained the detection limits for ADP under three different

  5. Development of active/adaptive lightweight optics for the next generation of telescopes

    Science.gov (United States)

    Ghigo, M.; Basso, S.; Citterio, O.; Mazzoleni, F.; Vernani, D.

    2006-02-01

    The future large optical telescopes will have such large dimensions to require innovative technical solutions either in the engineering and optical fields. Their optics will have dimensions ranging from 30 to 100 m. and will be segmented. It is necessary to develop a cost effective industrial process, fast and efficient, to create the thousands of segments neeededs to assemble the mirrors of these instruments. INAF-OAB (Astronomical Observatory of Brera) is developing with INAF-Arcetri (Florence Astronomical Observatory) a method of production of lightweight glass optics that is suitable for the manufacturing of these segments. These optics will be also probably active and therefore the segments have to be thin, light and relatively flexible. The same requirements are valid also for the secondary adaptive mirrors foreseen for these telescopes and that therefore will benefit from the same technology. The technique under investigation foresees the thermal slumping of thin glass segments using a high quality ceramic mold (master). The sheet of glass is placed onto the mold and then, by means of a suitable thermal cycle, the glass is softened and its shape is changed copying the master shape. At the end of the slumping the correction of the remaining errors will be performed using the Ion Beam Figuring technique, a non-contact deterministic technique. To reduce the time spent for the correction it will be necessary to have shape errors on the segments as small as possible. A very preliminary series of experiments already performed on reduced size segments have shown that it is possible to copy a master shape with high accuracy (few microns PV) and it is very likely that copy accuracies of 1 micron or less are possible. The paper presents in detail the concepts of the proposed process and describes our current efforts that are aimed at the production of a scaled demonstrative adaptive segment of 50 cm of diameter.

  6. On X-ray Optical Depth in the Coronae of Active Stars

    CERN Document Server

    Testa, Paola; Peres, Giovanni; Huenemoerder, David P

    2007-01-01

    We have investigated the optical thickness of the coronal plasma through the analysis of high-resolution X-ray spectra of a large sample of active stars observed with the High Energy Transmission Grating Spectrometer on Chandra. In particular, we probed for the presence of significant resonant scattering in the strong Lyman series lines arising from hydrogen-like oxygen and neon ions. The active RS CVn-type binaries II Peg and IM Peg and the single M dwarf EV Lac show significant optical depth. For these active coronae, the Lya/Lyb ratios are significantly depleted as compared with theoretical predictions and with the same ratios observed in similar active stars. Interpreting these decrements in terms of resonance scattering of line photons out of the line-of-sight, we are able to derive an estimate for the typical size of coronal structures, and from these we also derive estimates of coronal filling factors. For all three sources we find that the both the photon path length as a fraction of the stellar radiu...

  7. Wide-field optical mapping of neural activity and brain haemodynamics: considerations and novel approaches

    Science.gov (United States)

    Ma, Ying; Shaik, Mohammed A.; Kozberg, Mariel G.; Thibodeaux, David N.; Zhao, Hanzhi T.; Yu, Hang

    2016-01-01

    Although modern techniques such as two-photon microscopy can now provide cellular-level three-dimensional imaging of the intact living brain, the speed and fields of view of these techniques remain limited. Conversely, two-dimensional wide-field optical mapping (WFOM), a simpler technique that uses a camera to observe large areas of the exposed cortex under visible light, can detect changes in both neural activity and haemodynamics at very high speeds. Although WFOM may not provide single-neuron or capillary-level resolution, it is an attractive and accessible approach to imaging large areas of the brain in awake, behaving mammals at speeds fast enough to observe widespread neural firing events, as well as their dynamic coupling to haemodynamics. Although such wide-field optical imaging techniques have a long history, the advent of genetically encoded fluorophores that can report neural activity with high sensitivity, as well as modern technologies such as light emitting diodes and sensitive and high-speed digital cameras have driven renewed interest in WFOM. To facilitate the wider adoption and standardization of WFOM approaches for neuroscience and neurovascular coupling research, we provide here an overview of the basic principles of WFOM, considerations for implementation of wide-field fluorescence imaging of neural activity, spectroscopic analysis and interpretation of results. This article is part of the themed issue ‘Interpreting BOLD: a dialogue between cognitive and cellular neuroscience’. PMID:27574312

  8. Large High Performance Optics for Spaceborne Missions: L-3 Brashear Experience and Capability

    Science.gov (United States)

    Canzian, Blaise; Gardopee, George; Clarkson, Andrew; Hull, Tony; Borucki, William J.

    2010-01-01

    Brashear is a division of L-3 Communications, Integrated Optical Systems. Brashear is well known for the ground-based telescopes it has manufactured at its facilities and delivered to satisfied customers. Optics from meter-class up to 8.3 meters diameter have been fabricated in Brashear's facilities. Brashear has demonstrated capabilities for large spaceborne optics. We describe in this paper both legacy and new Brashear capabilities for high performance spaceborne optics.

  9. Twisted split-ring-resonator photonic metamaterial with huge optical activity

    CERN Document Server

    Decker, M; Soukoulis, C M; Linden, S; Wegener, M

    2010-01-01

    Coupled split-ring-resonator metamaterials have previously been shown to exhibit large coupling effects, which are a prerequisite for obtaining large effective optical activity. By a suitable lateral arrangement of these building blocks, we completely eliminate linear birefringence and obtain pure optical activity and connected circular optical dichroism. Experiments at around 100-THz frequency and corresponding modeling are in good agreement. Rotation angles of about 30 degrees for 205nm sample thickness are derived.

  10. Fibre-optic coupling to high-resolution CCD and CMOS image sensors

    Science.gov (United States)

    van Silfhout, R. G.; Kachatkou, A. S.

    2008-12-01

    We describe a simple method of gluing fibre-optic faceplates to complementary metal oxide semiconductor (CMOS) active pixel and charge coupled device (CCD) image sensors and report on their performance. Cross-sectional cuts reveal that the bonding layer has a thickness close to the diameter of the individual fibres and is uniform over the whole sensor area. Our method requires no special tools or alignment equipment and gives reproducible and high-quality results. The method maintains a uniform bond layer thickness even if sensor dies are mounted at slight angles with their package. These fibre-coupled sensors are of particular interest to X-ray imaging applications but also provide a solution for compact optical imaging systems.

  11. Fiber optical parametric oscillator based on highly nonlinear dispersion-shifted fiber

    Institute of Scientific and Technical Information of China (English)

    Sigang YANG; Kenneth K. Y. WONG; Minghua CHEN; Shizhong XIE

    2013-01-01

    The development of fiber optical parametric oscillators (FOPO) based on highly nonlinear dispersion- shifted fiber is reviewed in this paper. Firstly, the background and motivation are introduced, and it is pointed out that the FOPO is promising to act as optical source in non-conventional wavelength bands. Subsequently, the context focuses principally on the problem of inherent multiple-longitudinal-mode characteristic of FOPO and the corresponding solutions to it. The primary technique is by locking the phase of multiple longitudinal modes. The first reported actively mode locked FOPO is also presented in this article. However, it is not probable to realize passively mode locked FOPO because of the random phase dithering of the pump required for suppressing stimulated Brillouin scattering. Furthermore, a regeneratively mode locked FOPO is demonstrated, which can generate wide band tunable radiation in non- conventional wavelengths. Besides mode locked FOPO, the single-longitudinal-mode FOPO is also introduced. Finally, potential future directions are discussed.

  12. Beam divergence effects on high power optical parametric oscillation

    Institute of Scientific and Technical Information of China (English)

    Li Hui-Qing; Geng Ai-Cong; Bo Yong; Wu Ling-An; Cui Da-Fu; Xu Zu-Yan

    2005-01-01

    The beam divergence effects of the input pump laser on a high power nanosecond optical parametric oscillator (OPO) have been numerically simulated. The OPO conversion efficiency is affected due to the angular deviation of real laser beams from ideal phase matching conditions. Our theoretical model is based on the decomposition of the Gaussian beam and assumes each component has a single deviation angle and thus a Particular wave vector mismatch. We take into account the variable intensity profile in the spatial and temporal domains of the Gaussian beam, the pump depletion effects for large-signal processes as well as the oscillatory effects of the three waves. Two nonlinear crystals β-BaB2O4 (BBO) and LiB3O5 (LBO) have been investigated in detail. The results indicate that the degree of beam divergence strongly influences the maximum pump intensity, optimum crystal length and OPO conversion efficiency.The impact of beam divergence is much more severe in the case of critical phase-matching for BBO than in the case of non-critical phase-matching for LBO. The results provide a way to choose the optimum parameters for a high power ns OPO such as the nonlinear material, the crystal length and the pump intensity, etc. Good agreement is obtained with our experimental results.

  13. Bioinspired Superhydrophobic Highly Transmissive Films for Optical Applications.

    Science.gov (United States)

    Vüllers, Felix; Gomard, Guillaume; Preinfalk, Jan B; Klampaftis, Efthymios; Worgull, Matthias; Richards, Bryce; Hölscher, Hendrik; Kavalenka, Maryna N

    2016-11-01

    Inspired by the transparent hair layer on water plants Salvinia and Pistia, superhydrophobic flexible thin films, applicable as transparent coatings for optoelectronic devices, are introduced. Thin polymeric nanofur films are fabricated using a highly scalable hot pulling technique, in which heated sandblasted steel plates are used to create a dense layer of nano- and microhairs surrounding microcavities on a polymer surface. The superhydrophobic nanofur surface exhibits water contact angles of 166 ± 6°, sliding angles below 6°, and is self-cleaning against various contaminants. Additionally, subjecting thin nanofur to argon plasma reverses its surface wettability to hydrophilic and underwater superoleophobic. Thin nanofur films are transparent and demonstrate reflection values of less than 4% for wavelengths ranging from 300 to 800 nm when attached to a polymer substrate. Moreover, used as translucent self-standing film, the nanofur exhibits transmission values above 85% and high forward scattering. The potential of thin nanofur films for extracting substrate modes from organic light emitting diodes is tested and a relative increase of the luminous efficacy of above 10% is observed. Finally, thin nanofur is optically coupled to a multicrystalline silicon solar cell, resulting in a relative gain of 5.8% in photogenerated current compared to a bare photovoltaic device.

  14. Towards high-quality optical ceramic YAG fibers for high-energy laser (HEL) applications

    Science.gov (United States)

    Lee, HeeDong; Keller, Kristin; Sirn, Brian

    2012-06-01

    There is a critical demand for high quality, transparent ceramic YAG fibers for high powered fiber lasers. The production of laser quality ceramic fibers hinges on advanced ceramic processing technology, along with the availability of highly sinterable powder with high phase and chemical purity. These two fundamental technologies have been successfully developed at UES. Nd (1.1 a/o) and Yb (1.0 a/o)-doped yttrium aluminum garnet (YAG) fibers with high optical quality were produced by combining UES's tailored powders with advanced consolidation processes including fiber extrusion and vacuum sintering. The as-sintered and as-annealed fibers, approximately 30 microns in diameter, appeared transparent and successfully transmitted laser beams; further development will allow for the production of doped ceramic YAG fiber lasers for advanced high power and high energy fiber laser systems.

  15. High-order optical nonlinearities in nanocomposite films dispersed with semiconductor quantum dots at high concentrations

    Science.gov (United States)

    Tomita, Yasuo; Matsushima, Shun-suke; Yamagami, Ryu-ichi; Jinzenji, Taka-aki; Sakuma, Shohei; Liu, Xiangming; Izuishi, Takuya; Shen, Qing

    2017-06-01

    We describe the nonlinear optical properties of inorganic-organic nanocomposite films in which semiconductor CdSe quantum dots as high as 6.8 vol.% are dispersed. Open/closed Z-scan measurements, degenerate multi-wave mixing and femtosecond pump-probe/transient grating measurements are conducted. It is shown that the observed fifth-order optical nonlinearity has the cascaded third-order contribution that becomes prominent at high concentrations of CdSe QDs. It is also shown that there are picosecond-scale intensity-dependent and nanosecond-scale intensity-independent decay components in absorptive and refractive nonlinearities. The former is caused by the Auger process, while the latter comes from the electron-hole recombination process.

  16. High-power, high repetition-rate, green-pumped, picosecond LBO optical parametric oscillator.

    Science.gov (United States)

    Kienle, Florian; Teh, Peh Siong; Lin, Dejiao; Alam, Shaif-Ul; Price, Jonathan H V; Hanna, D C; Richardson, David J; Shepherd, David P

    2012-03-26

    We report on a picosecond, green-pumped, lithium triborate optical parametric oscillator with record-high output power. It was synchronously pumped by a frequency-doubled (530 nm), pulse-compressed (4.4 ps), high-repetition-rate (230 MHz), fiber-amplified gain-switched laser diode. For a pump power of 17 W, a maximum signal and idler power of 3.7 W and 1.8 W was obtained from the optical parametric oscillator. A signal pulse duration of ~3.2 ps was measured and wide tunability from 651 nm to 1040 nm for the signal and from 1081 nm to 2851 nm for the idler was achieved.

  17. Cavity Enhanced Optical Vernier Spectroscopy, Broad Band, High Resolution, High Sensitivity

    CERN Document Server

    Gohle, Christoph; Schliesser, Albert; Udem, Thomas; Hänsch, Theodor W

    2007-01-01

    A femtosecond frequency comb provides a vast number of equidistantly spaced narrow band laser modes that can be simultaneously tuned and frequency calibrated with 15 digits accuracy. Our Vernier spectrometer utilizes all of theses modes in a massively parallel manner to rapidly record both absorption and dispersion spectra with a sensitivity that is provided by a high finesse broad band optical resonator and a resolution that is only limited by the frequency comb line width while keeping the required setup simple.

  18. Calculation of Raman optical activity spectra for vibrational analysis.

    Science.gov (United States)

    Mutter, Shaun T; Zielinski, François; Popelier, Paul L A; Blanch, Ewan W

    2015-05-01

    By looking back on the history of Raman Optical Activity (ROA), the present article shows that the success of this analytical technique was for a long time hindered, paradoxically, by the deep level of detail and wealth of structural information it can provide. Basic principles of the underlying theory are discussed, to illustrate the technique's sensitivity due to its physical origins in the delicate response of molecular vibrations to electromagnetic properties. Following a short review of significant advances in the application of ROA by UK researchers, we dedicate two extensive sections to the technical and theoretical difficulties that were overcome to eventually provide predictive power to computational simulations in terms of ROA spectral calculation. In the last sections, we focus on a new modelling strategy that has been successful in coping with the dramatic impact of solvent effects on ROA analyses. This work emphasises the role of complementarity between experiment and theory for analysing the conformations and dynamics of biomolecules, so providing new perspectives for methodological improvements and molecular modelling development. For the latter, an example of a next-generation force-field for more accurate simulations and analysis of molecular behaviour is presented. By improving the accuracy of computational modelling, the analytical capabilities of ROA spectroscopy will be further developed so generating new insights into the complex behaviour of molecules.

  19. Origin invariance in vibrational resonance Raman optical activity

    Energy Technology Data Exchange (ETDEWEB)

    Vidal, Luciano N., E-mail: lnvidal@utfpr.edu.br; Cappelli, Chiara, E-mail: chiara.cappelli@unipi.it [Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Moruzzi 3, 56124 Pisa (Italy); Egidi, Franco [Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States); Barone, Vincenzo [Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa (Italy)

    2015-05-07

    A theoretical investigation on the origin dependence of the vibronic polarizabilities, isotropic and anisotropic rotational invariants, and scattering cross sections in Resonance Raman Optical Activity (RROA) spectroscopy is presented. Expressions showing the origin dependence of these polarizabilities were written in the resonance regime using the Franck-Condon (FC) and Herzberg-Teller (HT) approximations for the electronic transition moments. Differently from the far-from-resonance scattering regime, where the origin dependent terms cancel out when the rotational invariants are calculated, RROA spectrum can exhibit some origin dependence even for eigenfunctions of the electronic Hamiltonian. At the FC level, the RROA spectrum is completely origin invariant if the polarizabilities are calculated using a single excited state or for a set of degenerate states. Otherwise, some origin effects can be observed in the spectrum. At the HT level, RROA spectrum is origin dependent even when the polarizabilities are evaluated from a single excited state but the origin effect is expected to be small in this case. Numerical calculations performed for (S)-methyloxirane, (2R,3R)-dimethyloxirane, and (R)-4-F-2-azetidinone at both FC and HT levels using the velocity representation of the electric dipole and quadrupole transition moments confirm the predictions of the theory and show the extent of origin effects and the effectiveness of suggested ways to remove them.

  20. Optical Breath Gas Sensor for Extravehicular Activity Application

    Science.gov (United States)

    Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Pilgrim, Jeffrey S.; Chullen, Cinda; Falconi, Eric A.; McMillin, Summer

    2013-01-01

    The function of the infrared gas transducer used during extravehicular activity in the current space suit is to measure and report the concentration of carbon dioxide (CO2) in the ventilation loop. The next generation portable life support system (PLSS) requires next generation CO2 sensing technology with performance beyond that presently in use on the Space Shuttle/International Space Station extravehicular mobility unit (EMU). Accommodation within space suits demands that optical sensors meet stringent size, weight, and power requirements. A laser diode spectrometer based on wavelength modulation spectroscopy is being developed for this purpose by Vista Photonics, Inc. Two prototype devices were delivered to NASA Johnson Space Center (JSC) in September 2011. The sensors incorporate a laser diode-based CO2 channel that also includes an incidental water vapor (humidity) measurement and a separate oxygen channel using a vertical cavity surface emitting laser. Both prototypes are controlled digitally with a field-programmable gate array/microcontroller architecture. The present development extends and upgrades the earlier hardware to the Advanced PLSS 2.0 test article being constructed and tested at JSC. Various improvements to the electronics and gas sampling are being advanced by this project. The combination of low power electronics with the performance of a long wavelength laser spectrometer enables multi-gas sensors with significantly increased performance over that presently offered in the EMU.

  1. Realistic Instrumentation Platform for Active and Passive Optical Remote Sensing.

    Science.gov (United States)

    Brydegaard, Mikkel; Merdasa, Aboma; Gebru, Alem; Jayaweera, Hiran; Svanberg, Sune

    2016-02-01

    We describe the development of a novel versatile optical platform for active and passive remote sensing of environmental parameters. Applications include assessment of vegetation status and water quality. The system is also adapted for ecological studies, such as identification of flying insects including agricultural pests. The system is based on two mid-size amateur astronomy telescopes, continuous-wave diode lasers at different wavelengths ranging from violet to the near infrared, and detector facilities including quadrant photodiodes, two-dimensional and line scan charge-coupled device cameras, and a compact digital spectrometer. Application examples include remote Ramanlaser-induced fluorescence monitoring of water quality at 120 m distance, and insect identification at kilometer ranges using the recorded wing beat frequency and its spectrum of overtones. Because of the low cost this developmental platform is very suitable for advanced research projects in developing countries and has, in fact, been multiplied during hands-on workshops and is now being used by a number of groups at African universities. © The Author(s) 2016.

  2. Opportunities for optics within high-tech of tomorrow

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner; Jakobsen, Michael Linde; Iversen, Theis F. Q.;

    2011-01-01

    The use of miniaturized optical sensors as input devices based on speckle phenomena will be discussed alongside with some considerations on the path to industrial implementation.......The use of miniaturized optical sensors as input devices based on speckle phenomena will be discussed alongside with some considerations on the path to industrial implementation....

  3. Parallel particle identification and separation for active optical sorting

    DEFF Research Database (Denmark)

    Perch-Nielsen, Ivan R.; Palima, Darwin; Dam, Jeppe Seidelin

    2009-01-01

    matched with a rapidly reconfigurable optical sorting field. We demonstrate the potential of such a system using colloidal polystyrene microspheres. By combining machine vision with a parallel add-on optical manipulation scheme, we were able to move identified particles over a distance of several hundred...

  4. Exploring the active site structure of photoreceptor proteins by Raman optical activity

    Science.gov (United States)

    Unno, Masashi

    2015-03-01

    Understanding protein function at the atomic level is a major challenge in a field of biophysics and requires the combined efforts of structural and functional methods. We use photoreceptor proteins as a model system to understand in atomic detail how a chromophore and a protein interact to sense light and send a biological signal. A potential technique for investigating molecular structures is Raman optical activity (ROA), which is a spectroscopic method with a high sensitivity to the structural details of chiral molecules. However, its application to photoreceptor proteins has not been reported. Thus we have constructed ROA spectrometer using near-infrared (NIR) laser excitation at 785 nm. The NIR excitation enables us to measure ROA spectra for a variety of biological samples, including photoreceptor proteins, without fluorescence from the samples. In the present study, we have applied the NIR-ROA to bacteriorhodopsin (BR) and photoactive yellow protein (PYP). BR is a light-driven proton pump and contains a protonated Schiff base of retinal as a chromophore. PYP is a blue light receptor, and this protein has the 4-hydroxycinnamyl chromophore, which is covalently linked to Cys69 through a thiolester bond. We have successfully obtained the ROA spectra of the chromophore within a protein environment. Furthermore, calculations of the ROA spectra utilizing density functional theory provide detailed structural information, such as data on out-of-plane distortions of the chromophore. The structural information obtained from the ROA spectra includes the positions of hydrogen atoms, which are usually not detected in the crystal structures of biological samples.

  5. Optical Basicity and Nepheline Crystallization in High Alumina Glasses

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Carmen P.; McCloy, John S.; Schweiger, M. J.; Crum, Jarrod V.; Winschell, Abigail E.

    2011-02-25

    The purpose of this study was to find compositions that increase waste loading of high-alumina wastes beyond what is currently acceptable while avoiding crystallization of nepheline (NaAlSiO4) on slow cooling. Nepheline crystallization has been shown to have a large impact on the chemical durability of high-level waste glasses. It was hypothesized that there would be some composition regions where high-alumina would not result in nepheline crystal production, compositions not currently allowed by the nepheline discriminator. Optical basicity (OB) and the nepheline discriminator (ND) are two ways of describing a given complex glass composition. This report presents the theoretical and experimental basis for these models. They are being studied together in a quadrant system as metrics to explore nepheline crystallization and chemical durability as a function of waste glass composition. These metrics were calculated for glasses with existing data and also for theoretical glasses to explore nepheline formation in Quadrant IV (passes OB metric but fails ND metric), where glasses are presumed to have good chemical durability. Several of these compositions were chosen, and glasses were made to fill poorly represented regions in Quadrant IV. To evaluate nepheline formation and chemical durability of these glasses, quantitative X-ray diffraction (XRD) analysis and the Product Consistency Test were conducted. A large amount of quantitative XRD data is collected here, both from new glasses and from glasses of previous studies that had not previously performed quantitative XRD on the phase assemblage. Appendix A critically discusses a large dataset to be considered for future quantitative studies on nepheline formation in glass. Appendix B provides a theoretical justification for choice of the oxide coefficients used to compute the OB criterion for nepheline formation.

  6. Monolithic integration of optical mode-size converter and high-speed electroabsorption modulators using laterally undercut waveguide

    Science.gov (United States)

    Wu, Tsu-Hsiu; Lin, Fang-Zheng; Yan, Hung-Jung; Wu, Jui-Pin; Chiu, Yi-Jen

    2010-02-01

    A new monolithic integration scheme of fabricating optical spot-size converter (SSC) is realized in this work. High-speed electroabsorption modulator (EAM) is used to integrate such SSC. By laterally tapering the active region of an optical waveguide through undercut active region, a vertically asymmetric waveguide coupler can be defined to form an SSC, where the top is a tapered active waveguide, and the bottom is a large core of passive waveguide mode-matched to single-mode fiber (SMF). Through the top tapered active waveguide, the effective index can be gradually varied in the propagation direction, momentarily matching the bottom low-index passive waveguide. It not only performs the resonant coupling in such asymmetric waveguide coupler, but also locks the transferred power by the tapered structure. InGaAsP/InP multiple quantum wells are used as active region of active waveguide. Based on the highly selective etching properties between InGaAsP and InP, the tapered active waveguide can be fabricated by a method, called selectively undercut-etching-active-region (UEAR), enabling the processing a narrow waveguide structure (up to submicron) by general wet etching from a large waveguide ridge. It also leads to good microwave performance of waveguide. By taking this advantage, a SSC-integrated EAM can perform high-speed electrical-to-optical (EO) response as well as low-insertion loss properties. A mode transfer efficiency of 70% is obtained in such SSC. By narrowing waveguide by UEAR, over 40 GHz of -3dB electrical-to-optical (EO) response is obtained from this device. The high efficient SSC integrated with high-speed EAM suggests that the UEAR technique can have potential for applications in high-speed optoelectronic fields.

  7. Infrared optical activity: electric field approaches in time domain.

    Science.gov (United States)

    Rhee, Hanju; Choi, Jun-Ho; Cho, Minhaeng

    2010-12-21

    Vibrational circular dichroism (VCD) spectroscopy provides detailed information about the absolute configurations of chiral molecules including biomolecules and synthetic drugs. This method is the infrared (IR) analogue of the more popular electronic CD spectroscopy that uses the ultraviolet and visible ranges of the electromagnetic spectrum. Because conventional electronic CD spectroscopy measures the difference in signal intensity, problems such as weak signal and low time-resolution can limit its utility. To overcome the difficulties associated with that approach, we have recently developed femtosecond IR optical activity (IOA) spectrometry, which directly measures the IOA free-induction-decay (FID), the impulsive chiroptical IR response that occurs over time. In this Account, we review the time-domain electric field measurement and calculation methods used to simultaneously characterize VCD and related vibrational optical rotatory dispersion (VORD) spectra. Although conventional methods measure the electric field intensity, this vibrational technique is based on a direct phase-and-amplitude measurement of the electric field of the chiroptical signal over time. This method uses a cross-polarization analyzer to carry out heterodyned spectral interferometry. The cross-polarization scheme enables us to selectively remove the achiral background signal, which is the dominant noise component present in differential intensity measurement techniques. Because we can detect the IOA FID signal in a phase-amplitude-sensitive manner, we can directly characterize the time-dependent electric dipole/magnetic dipole response function and the complex chiral susceptibility that contain information about the angular oscillations of charged particles. These parameters yield information about the VCD and VORD spectra. In parallel with such experimental developments, we have also calculated the IOA FID signal and the resulting VCD spectrum. These simulations use a quantum mechanical

  8. Chemoenzymatic collective synthesis of optically active hydroxyl(methyl)tetrahydronaphthalene-based bioactive terpenoids.

    Science.gov (United States)

    Batwal, Ramesh U; Argade, Narshinha P

    2015-12-14

    Starting from succinic anhydride and 2-methylanisole, a chemoenzymatic collective formal/total synthesis of several optically active tetrahydronaphthalene based bioactive natural products has been presented via advanced level common precursors; the natural product and antipode (-)/(+)-aristelegone B. Regioselective benzylic oxidations, stereoselective introduction of hydroxyl groups at the α-position of ketone moiety in syn-orientation, efficient enzymatic resolutions with high enantiomeric purity, stereoselective reductions, samarium iodide induced deoxygenations and tandem acylation-Wittig reactions without racemization and/or eliminative aromatization were the key features. An attempted diastereoselective synthesis of (±)-vallapin has also been described.

  9. Proven high-reliability assembly methods applied to avionics fiber-optics high-speed transceivers

    Science.gov (United States)

    Lauzon, Jocelyn; Leduc, Lorrain; Bessette, Daniel; Bélanger, Nicolas; Larose, Robert; Dion, Bruno

    2012-06-01

    Harsh environment avionics applications require operating temperature ranges that can extend to, and exceed -50 to 115°C. For obvious maintenance, management and cost arguments, product lifetimes as long as 20 years are also sought. This leads to mandatory long-term hermeticity that cannot be obtained with epoxy or silicone sealing; but only with glass seal or metal solder or brazing. A hermetic design can indirectly result in the required RF shielding of the component. For fiber-optics products, these specifications need to be compatible with the smallest possible size, weight and power consumption. The products also need to offer the best possible high-speed performances added to the known EMI immunity in the transmission lines. Fiber-optics transceivers with data rates per fiber channel up to 10Gbps are now starting to be offered on the market for avionics applications. Some of them are being developed by companies involved in the "normal environment" telecommunications market that are trying to ruggedize their products packaging in order to diversify their customer base. Another approach, for which we will present detailed results, is to go back to the drawing boards and design a new product that is adapted to proven MIL-PRF-38534 high-reliability packaging assembly methods. These methods will lead to the introduction of additional requirements at the components level; such as long-term high-temperature resistance for the fiber-optic cables. We will compare both approaches and demonstrate the latter, associated with the redesign, is the preferable one. The performance of the fiber-optic transceiver we have developed, in terms of qualification tests such as temperature cycling, constant acceleration, hermeticity, residual gaz analysis, operation under random vibration and mechanical shocks and accelerated lifetime tests will be presented. The tests are still under way, but so far, we have observed no performance degradation of such a product after more than

  10. Planning High-Risk High-Reward Activities.

    NARCIS (Netherlands)

    Casault, Sébastien

    2014-01-01

    This body of work addresses a gap in financial and economic theories related to assets that are typically associated with high uncertainty. Specifically, this thesis provides some foundational work towards a new way to quantify and explain how high-risk high-reward activities, such as exploration,

  11. Optical Diagnostics for High-Temperature Thermal Barrier Coatings

    Science.gov (United States)

    Eldridge, Jeffrey I.

    2009-01-01

    Thermal barrier coatings (TBCs) are typically composed of translucent ceramic oxides that provide thermal protection for metallic components exposed to high-temperature environments, such as in jet turbine engines. Taking advantage of the translucent nature of TBCs, optical diagnostics have been developed that can provide an informed assessment of TBC health that will allow mitigating action to be taken before TBC degradation threatens performance or safety. In particular, rare-earth-doped luminescent sublayers have been integrated into the TBC structure to produce luminescence that monitors TBC erosion, delamination, and temperature gradients. Erosion monitoring of TBC-coated specimens is demonstrated by utilizing visible luminescence that is excited from a sublayer that is exposed by erosion. TBC delamination monitoring is achieved in TBCs with a base rare-earth-doped luminescent sublayer by the reflectance-enhanced increase in luminescence produced in regions containing buried delamination cracks. TBC temperature monitoring is demonstrated using the temperature-dependent decay time for luminescence originating from the specific coating depth associated with a rare-earth-doped luminescent sublayer. The design and implementation of these TBCs with integrated luminescent sublayers is discussed, including co-doping strategies to produce more penetrating near-infrared luminescence. It is demonstrated that integration of the rare-earth-doped sublayers is achieved with no reduction in TBC life. In addition, results for multilayer TBCs designed to also perform as radiation barriers are also presented.

  12. High efficiency holographic Bragg grating with optically prolonged memory

    Science.gov (United States)

    Khoo, Iam Choon; Chen, Chun-Wei; Ho, Tsung-Jui

    2016-10-01

    In this paper, we show that photosensitive azo-dye doped Blue-phase liquid crystals (BPLC) formed by natural molecular self-assembly are capable of high diffraction efficiency holographic recording with memory that can be prolonged from few seconds to several minutes by uniform illumination with the reference beam. Operating in the Bragg regime, we have observed 50 times improvement in the grating diffraction efficiency and shorter recording time compared to previous investigations. The enabling mechanism is BPLC’s lattice distortion and index modulation caused by the action of light on the azo-dopant; upon photo-excitation, the azo-molecules undergo transformation from the oblong-shaped Trans-state to the bent-shaped Cis-state, imparting disorder and also cause the surrounding BPLC molecules to undergo coupled flow & reorientation leading to lattice distortion and index modulation. We also showed that the same mechanism at work here that facilitates lattice distortion can be used to frustrate free relaxation of the lattice distortion, thereby prolonging the lifetime of the written grating, provided the reference beam is kept on after recording. Due to the ease in BPLC fabrication and the availability of azo-dopants with photosensitivity throughout the entire visible spectrum, one can optimize the controlling material and optical parameters to obtain even better performance.

  13. Development of high $\\beta^*$-optics for ALICE

    CERN Document Server

    Hermes, Pascal Dominik; Wessels, Johannes Peter

    This thesis describes a feasibility study for a special optical configuration in Insertion Region 2 (IR2) of the Large Hadron Collider (LHC), which is host of the ALICE detector. This configuration allows the study of elastic and diffractive scattering during LHC high-intensity proton operation, in parallel to the nominal physics studies in all LHC experiments at the design energy of 7 TeV per beam. Such measurements require the instal- lation of additional Roman Pot (RP) detectors in the very forward region, at longitudinal distances of 150 m to 220 m from the Interaction Point (IP). Apart from being adjusted for a specific betatron phase advance between the IP and the RP detectors, such a configuration must be optimized for the largest possible $\\beta^*$ -value, to be sensitive for the smallest possible four-momentum transfer $|t|$. A value of $\\beta^*$ = 18 m is compatible with a bunch spacing of 25 ns, considering the LHC design emittance of N = 3.75 μm rad, and a required bunch-bunch separation of $12 \\...

  14. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  15. Focal-plane wavefront sensing for active optics in the VST based on an analytical optical aberration model

    Science.gov (United States)

    Holzlöhner, R.; Taubenberger, S.; Rakich, A. P.; Noethe, L.; Schipani, P.; Kuijken, K.

    2016-08-01

    We study a novel focal plane wavefront sensing and active optics control scheme at the VST on Cerro Paranal, an f/5.5 survey telescope with a 1x1 degree field of view and a 2.6m primary mirror. This scheme analyzes the elongation pattern of stellar PSFs across the full science image (256 Mpixels) and compares their second moments with an analytical model based on 5th-order geometrical optics. We consider 11 scalar degrees of freedom in mirror misalignments and deformations (M2 piston, tip/tilt and lateral displacement, detector tip/tilt, plus M1 figure astigmatism and trefoil). Using a numerical optimization method, we extract up to 4000 stars and complete the fitting process in under one minute. We demonstrate successful closed-loop active optics control based on maximum likelihood filtering.

  16. Radiation-hard/high-speed parallel optical links

    Energy Technology Data Exchange (ETDEWEB)

    Gan, K.K., E-mail: gan@mps.ohio-state.edu [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Buchholz, P.; Heidbrink, S. [Fachbereich Physik, Universität Siegen, Siegen (Germany); Kagan, H.P.; Kass, R.D.; Moore, J.; Smith, D.S. [Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Vogt, M.; Ziolkowski, M. [Fachbereich Physik, Universität Siegen, Siegen (Germany)

    2016-09-21

    We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

  17. Radiation-hard/high-speed parallel optical links

    Science.gov (United States)

    Gan, K. K.; Buchholz, P.; Heidbrink, S.; Kagan, H. P.; Kass, R. D.; Moore, J.; Smith, D. S.; Vogt, M.; Ziolkowski, M.

    2016-09-01

    We have designed and fabricated a compact parallel optical engine for transmitting data at 5 Gb/s. The device consists of a 4-channel ASIC driving a VCSEL (Vertical Cavity Surface Emitting Laser) array in an optical package. The ASIC is designed using only core transistors in a 65 nm CMOS process to enhance the radiation-hardness. The ASIC contains an 8-bit DAC to control the bias and modulation currents of the individual channels in the VCSEL array. The performance of the optical engine up at 5 Gb/s is satisfactory.

  18. High Speed 1.55 μm Lasers for Fiber Optic Transmission

    Science.gov (United States)

    Morton, Paul A.

    This paper describes the essential elements for creating a practical wide bandwidth directly modulated laser source. This includes considerations of the intrinsic limitations of the laser structure, due to the resonant frequency and damping of the laser output, together with carrier transport issues to allow carriers in the device active region to be efficiently modulated at high speeds. The use of a P-doped compressively strained multiple-quantum well active region to provide high intrinsic speed and remove transport limitations is described, together with record setting results of 25 GHz modulation bandwidth for a 1.55 μm Fabry-Perot laser and 26 GHz bandwidth for a 1.55 μm DFB laser. The challenges of providing high bandwidth electrical connections to the laser on a suitable submount, together with fiber attachment and microwave packaging are discussed. Results of fully packaged 1.55 μm DFB lasers with 25 GHz modulation bandwidth are shown. Digital modulation of the packaged 1.55 μm DFB including impedance matching is described, and the transient wavelength chirp is presented. This low chirp is reduced further using an optical filter, to provide a 10 GBit/s source that can transmit error free over 38.5 km of standard optical fiber.

  19. Large Optical Telescope Based on High Efficiency Thin Film Planar Diffractive Optics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In future ground-based receivers for deep-space optical communications with spacecraft, aperture diameters of the order of 10 meters are required even with the most...

  20. High Performance Fiber-Optic Sensor for Environmental Monitoring Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Los Gatos Research (LGR) proposes to develop a low-cost, compact, lightweight, rugged and easy-to-use environmental monitoring optical fiber sensor device based on...

  1. Ultra-high Frequency Linear Fiber Optic Systems

    CERN Document Server

    Lau, Kam Y

    2009-01-01

    Designed for a one-semester course on fiber-optics systems and communication links, this book provides a concise but rigorous treatment of the theory and practice of analog (linear) fiber-optics links and systems that constitute the foundation of Hybrid Fiber Coax infrastructure in present-day CATV distribution and cable modem Internet access. Emerging applications in remote fiber-optic feed for free-space millimeter wave enterprise campus networks are also described. Issues such as dispersion and interferometric noise are treated quantitatively, and means for mitigating them are explained. This broad but concise text will thus be invaluable not only to students of fiber-optics communication but also to practicing engineers.

  2. Application of Nanophotonic Devices in High Speed Optical Communications

    DEFF Research Database (Denmark)

    Vukovic, Dragana

    highcapacity fiber-optic transmission systems including switching nodes, crossconnectors and add-drop multiplexers. One of the expected key advantages of wavelength converters based on four-wave mixing in nonlinear media exhibiting third-order nonlinearities is the possibility for modulation format and bit......-chip photonic networks. In this thesis, the use of a indium phosphide (InP) photonic crystal nanocavity to perform optical switching that is compatible with telecommunication signals has been demonstrated. Cavity switching induced by free carrier generation was achieved in the GHz range with very low energy......All-optical signal processing has attracted a significant research interest in the past decade as it might become competitive with electronics in terms of compactness, energy consumption, and reliability. Furthermore it might solve the current bandwidth mismatch between optical transmission...

  3. Adaptive optics technology for high-resolution retinal imaging.

    Science.gov (United States)

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2012-12-27

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  4. Adaptive Optics Technology for High-Resolution Retinal Imaging

    Directory of Open Access Journals (Sweden)

    Giuseppe Lombardo

    2012-12-01

    Full Text Available Adaptive optics (AO is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  5. Optical sum rule anomalies in high-temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Toschi, Alessandro; Sangiovanni, Giorgio; Held, Karsten [Institut fuer Festkoerperphysik, Technische Universitaet Wien (Austria); Capone, Massimo [Dipartimento di Fisica, Universita ' ' La Sapienza' ' , Roma (Italy); SMC, CNR-INFM, Roma (Italy); Castellani, Claudio [Dipartimento di Fisica, Universita ' ' La Sapienza' ' , Roma (Italy)

    2009-07-01

    Many unusual features recently observed in the optical spectroscopy experiments in the cuprates can be simply understood as arising from the vicinity to the Mott transition, without invoking more involved and exotic mechanisms. Specifically, we compare calculations based on the Dynamical Mean Field Theory (DMFT) of the Hubbard model with the optical spectral weight W{sub opt} of different cuprates, explaining most of the anomalies found in the optical sum rules with respect to normal metals, including the existence of two different energy scales for the doping- and the T-dependence of W{sub opt}. A further support to this result is provided by the analysis of the optical conductivity in a typical case of the Mott-Hubbard metal-insulator transition, namely the V{sub 2}O{sub 3}.

  6. Three-dimensional packaging of very large scale integrated optics (VLSIO) for high-complexity optical systems

    Science.gov (United States)

    West, Lawrence C.; Roberts, Charles W.; Piscani, Emil C.; Dubey, Madan; Jones, Kenneth A.; McLane, George F.

    1996-03-01

    Optics has the fundamental capability of dramatically improving computer performance via the reduction of capacitance for intrinsic high bandwidth communications and low power usage. Yet optical devices have not displaced silicon VLSI in any measure to date. The reason is clear. When placed into systems, the optical devices have not had significantly greater performance in equally complex information processing circuits and similarly low manufacturing cost. An approach demonstrated here uses the same system integration techniques that have been successful for silicon electronics, only applied to optics. Essential for creation of very large scale integrated optics (VLSIO), with over 50,000 high speed logic gates per square centimeter, is a new class of ultra high confinement (UHC) waveguides. These waveguides are created with high index difference (as high as 4.0 to 1.0) between guide and cladding. The waveguides have been demonstrated with infrared cross sections less than 5% of a square free space wavelength. These waveguides can be manufactured today only in the mid-infrared, but the concepts should scale to the near-infrared as lithography improves. Waveguide corners have been designed and demonstrated with a bend radius of less than one free space wavelength. Resonators have been designed which have over 100 times smaller volume than VCSELs, yet efficiently inter-connected laterally in high densities. A connector to the UHC waveguides has been developed and demonstrated using diffractive optical element arrays on the back side of the substrate. The coupler arrays can allow up to 10,000 Gaussian beam connections per square centimeter. This connectivity also has advantages for low cost three dimensional packaging for reduced cost and thermal dissipation. Experimental results on the above concepts and components are presented.

  7. Computerized Stokes analysis of optically active polymer films

    CERN Document Server

    Georgiev, Georgi

    2010-01-01

    Optics labs are an integral part of the advanced curriculum for physics majors. Students majoring in other disciplines, like chemistry, biology or engineering rarely have the opportunity to learn about the most recent optical techniques and mathematical representation used in today’s science and industry optics. Stokes analysis of polarization of light is one of those methods that are increasingly necessary but are seldom taught outside advanced physics or optics classes that are limited to physics majors. On the other hand biology and chemistry majors already use matrix and polarization techniques in the labs for their specialty, which makes the transition to matrix calculations seamless. Since most of the students in those majors postpone their enrollment in physics, most of the registered in those classes are juniors and seniors, enabling them to handle those techniques. We chose to study polymer samples to aid students majoring in other disciplines, especially chemistry and engineering, with understa...

  8. Opportunities for optics within tomorrow’s high-tech

    OpenAIRE

    Hanson, Steen Grüner

    2012-01-01

    The use of miniaturized optical sensors as input devices based on speckle phenomena will be discussed alongside with some considerations on the path to industrial implementation. Based on two examples from the field of cursor control systems, the future opportunities for dissemination into industrial applications will be discussed, in particular, optically based systems for monitoring dynamics of solid structures, e.g. rotational speed, torsional vibrations and velocity. Here, the commonly re...

  9. High speed optical object recognition processor with massive holographic memory

    Science.gov (United States)

    Chao, T.; Zhou, H.; Reyes, G.

    2002-01-01

    Real-time object recognition using a compact grayscale optical correlator will be introduced. A holographic memory module for storing a large bank of optimum correlation filters, to accommodate the large data throughput rate needed for many real-world applications, has also been developed. System architecture of the optical processor and the holographic memory will be presented. Application examples of this object recognition technology will also be demonstrated.

  10. Multimode fiber for high-density optical interconnects

    Science.gov (United States)

    Bickham, Scott R.; Ripumaree, Radawan; Chalk, Julie A.; Paap, Mark T.; Hurley, William C.; McClure, Randy L.

    2017-02-01

    Data centers (DCs) are facing the challenge of delivering more capacity over longer distances. As line rates increase to 25 Gb/s and higher, DCs are being challenged with signal integrity issues due to the long electrical traces that require retiming. In addition, the density of interconnects on the front panel is limited by the size and power dissipation requirements of the pluggable modules. One proposal to overcome these issues is to use embedded optical transceivers in which optical fibers are used to transport data to and from the front panel. These embedded modules will utilize arrays of VCSEL or silicon-photonic transceivers, and in both cases, the capacity may be limited by the density of the optical connections on the chip. To address this constraint, we have prototyped optical fibers in which the glass and coating diameters are reduced to 80 and 125 microns, respectively. These smaller diameters enable twice as many optical interconnects in the same footprint, and this in turn will allow the transceiver arrays to be collinearly located on small chips with dimensions on the order of (5x5mm2)1,2. We have also incorporated these reduced diameter fibers into small, flexible 8-fiber ribbon cables which can simplify routing constraints inside modules and optical backplanes.

  11. Multimodal adaptive optics for depth-enhanced high-resolution ophthalmic imaging

    Science.gov (United States)

    Hammer, Daniel X.; Mujat, Mircea; Iftimia, Nicusor V.; Lue, Niyom; Ferguson, R. Daniel

    2010-02-01

    We developed a multimodal adaptive optics (AO) retinal imager for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa (RP). The development represents the first ever high performance AO system constructed that combines AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. The SSOCT channel operates at a wavelength of 1 μm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. The system is designed to operate on a broad clinical population with a dual deformable mirror (DM) configuration that allows simultaneous low- and high-order aberration correction. The system also includes a wide field line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation; an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of rotational eye motion; and a high-resolution LCD-based fixation target for presentation to the subject of stimuli and other visual cues. The system was tested in a limited number of human subjects without retinal disease for performance optimization and validation. The system was able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 μm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve targets deep into the choroid. In addition to instrument hardware development, analysis algorithms were developed for efficient information extraction from clinical imaging sessions, with functionality including automated image registration, photoreceptor counting, strip and montage stitching, and segmentation. The system provides clinicians and researchers with high-resolution, high performance adaptive optics imaging to help

  12. High effective silica fume alkali activator

    Indian Academy of Sciences (India)

    Vladimír Živica

    2004-04-01

    Growing demands on the engineering properties of cement based materials and the urgency to decrease unsuitable ecologic impact of Portland cement manufacturing represent significant motivation for the development of new cement corresponding to these aspects. One category represents prospective alkali activated cements. A significant factor influencing their properties is alkali activator used. In this paper we present a new high effective alkali activator prepared from silica fume and its effectiveness. According to the results obtained this activator seems to be more effective than currently used activators like natrium hydroxide, natrium carbonate, and water glass.

  13. High-resolution optical spectroscopy of Plaskett's star

    Science.gov (United States)

    Linder, N.; Rauw, G.; Martins, F.; Sana, H.; De Becker, M.; Gosset, E.

    2008-10-01

    Context: Plaskett's star (HD 47 129) is a very massive O + O binary that belongs to the Mon OB2 association. Previous work suggests that this system displays the Struve-Sahade effect although the measurements of the secondary radial velocities are very difficult and give controversial results. Both components have powerful stellar winds that collide and produce a strong X-ray emission. Aims: Our aim is to study the physical parameters of this system in detail and to investigate the relation between its spectral properties and its evolutionary status. Methods: We present here analysis of an extensive set of high-resolution optical spectra of HD 47 129. We used a disentangling method to separate the individual spectra of each star. We derived a new orbital solution and discuss the spectral classification of both components. A Doppler tomography technique applied to the emission lines Hα and He II λ 4686 yields a Doppler map that illustrates the wind interactions in the system. Finally, an atmosphere code is used to determine the different chemical abundances of the system components and the wind parameters. Results: HD 47 129 appears to be an O8 III/I + O7.5 III binary system in a post RLOF evolutionary stage, where matter has been transferred from the primary to the secondary star. The He overabundance of the secondary supports this scenario. In addition, the N overabundance and C underabundance of the primary component confirm previous results based on X-ray spectroscopy and indicate that the primary is an evolved massive star. We also determined a new orbital solution, with MP sin^3i = 45.4 ± 2.4 M⊙ and MS sin^3i = 47.3 ± 0.3 M⊙. Furthermore, the secondary star has a high rotational velocity (v sin i ˜ 300 km s-1) that deforms its surface, leading to a non-uniform distribution in effective temperature. This could explain the variations in the equivalent widths of the secondary lines with phase. We suggest that the wind of the secondary star is confined

  14. All-optical random number generation using highly nonlinear fibers by numerical simulation

    Science.gov (United States)

    Wang, Juanfen; Liang, Junqiang; Li, Pu; Yang, Lingzhen; Wang, Yuncai

    2014-06-01

    A new scheme of all-optical random number generation based on the nonlinear effects in highly nonlinear fibers (HNLF) is proposed. The scheme is comprised of ultra-wide band chaotic entropy source, all-optical sampler, all-optical comparator and all-optical exclusive-or (XOR), which are mainly realized by four-wave mixing (FWM) and cross-phase modulation (XPM) in highly nonlinear fibers. And we achieve 10 Gbit/s random numbers through numerically simulating all the processes. The entire operations are completed in the all-optical domain, which may overcome the bottleneck problem of electronic devices, and apply directly in high-speed all-optical communication network.

  15. High resolution mesospheric sodium properties for adaptive optics applications

    Science.gov (United States)

    Pfrommer, T.; Hickson, P.

    2014-05-01

    Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a

  16. Large motion high cycle high speed optical fibers for space based applications.

    Energy Technology Data Exchange (ETDEWEB)

    Stromberg, Peter G. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Tandon, Rajan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gibson, Cory S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Reedlunn, Benjamin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rasberry, Roger David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rohr, Garth David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-10-01

    Future remote sensing applications will require higher resolution and therefore higher data rates (up to perhaps 100 gigabits per second) while achieving lower mass and cost. A current limitation to the design space is high speed high bandwidth data does not cross movable gimbals because of cabling issues. This requires the detectors to be off gimbal. The ability to get data across the gimbal would open up efficiencies in designs where the detectors and the electronics can be placed anywhere on the system. Fiber optic cables provide light weight high speed high bandwidth connections. Current options are limited to 20,000 cycles as opposed to the 1,000,000 cycles needed for future space based applications. To extend this to the million+ regime, requires a thorough understanding of the failure mechanisms and the materials, proper selection of materials (e.g., glass and jacket material) allowable geometry changes to the cable, radiation hardness, etc.

  17. Evaluating a genetically encoded optical sensor of neural activity using electrophysiology in intact adult fruit flies

    Directory of Open Access Journals (Sweden)

    Gilles Laurent

    2007-11-01

    Full Text Available Genetically encoded optical indicators hold the promise of enabling non-invasive monitoring of activity in identified neurons in behaving organisms. However, the interpretation of images of brain activity produced using such sensors is not straightforward. Several recent studies of sensory coding used G-CaMP 1.3-a calcium sensor-as an indicator of neural activity; some of these studies characterized the imaged neurons as having narrow tuning curves, a conclusion not always supported by parallel electrophysiological studies. To better understand the possible cause of these conflicting results, we performed simultaneous in vivo 2-photon imaging and electrophysiological recording of G-CaMP 1.3 expressing neurons in the antennal lobe (AL of intact fruitflies. We find that G-CaMP has a relatively high threshold, that its signal often fails to capture spiking response kinetics, and that it can miss even high instantaneous rates of activity if those are not sustained. While G-CaMP can be misleading, it is clearly useful for the identification of promising neural targets: when electrical activity is well above the sensor's detection threshold, its signal is fairly well correlated with mean firing rate and G-CaMP does not appear to alter significantly the responses of neurons that express it. The methods we present should enable any genetically encoded sensor, activator, or silencer to be evaluated in an intact neural circuit in vivo in Drosophila.

  18. Recent Progress in Silicon Electro-optic Modulators for High Speed Applications

    Institute of Scientific and Technical Information of China (English)

    XIAO Xi; YU Jin-zhong

    2008-01-01

    Silicon-based high-speed electro-optical modulator is the key component of silicon photonics for future communiction and interconnection systems. In this paper, introduced are the optical mudulation mechanisms in silicon, reviewed are some recent progresses in high-speed silicon modulators, and analyzed are advantages and shortages of the silicon modulators of different types.

  19. Achieving High-Frequency Optical Control of Synaptic Transmission

    Science.gov (United States)

    Jackman, Skyler L.; Beneduce, Brandon M.; Drew, Iain R.

    2014-01-01

    The optogenetic tool channelrhodopsin-2 (ChR2) is widely used to excite neurons to study neural circuits. Previous optogenetic studies of synapses suggest that light-evoked synaptic responses often exhibit artificial synaptic depression, which has been attributed to either the inability of ChR2 to reliably fire presynaptic axons or to ChR2 elevating the probability of release by depolarizing presynaptic boutons. Here, we compare light-evoked and electrically evoked synaptic responses for high-frequency stimulation at three synapses in the mouse brain. At synapses from Purkinje cells to deep cerebellar nuclei neurons (PC→DCN), light- and electrically evoked synaptic currents were remarkably similar for ChR2 expressed transgenically or with adeno-associated virus (AAV) expression vectors. For hippocampal CA3→CA1 synapses, AAV expression vectors of serotype 1, 5, and 8 led to light-evoked synaptic currents that depressed much more than electrically evoked currents, even though ChR2 could fire axons reliably at up to 50 Hz. The disparity between optical and electrical stimulation was eliminated when ChR2 was expressed transgenically or with AAV9. For cerebellar granule cell to stellate cell (grc→SC) synapses, AAV1 also led to artificial synaptic depression and AAV9 provided superior performance. Artificial synaptic depression also occurred when stimulating over presynaptic boutons, rather than axons, at CA3→CA1 synapses, but not at PC→DCN synapses. These findings indicate that ChR2 expression methods and light stimulation techniques influence synaptic responses in a neuron-specific manner. They also identify pitfalls associated with using ChR2 to study synapses and suggest an approach that allows optogenetics to be applied in a manner that helps to avoid potential complications. PMID:24872574

  20. Optically active substituted polyacetylene@carbon nanotube hybrids: Preparation, characterization and infrared emissivity property study

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Xiaohai; Zhou, Yuming, E-mail: ymzhou@seu.edu.cn; Zhang, Tao; Wang, Yongjuan; Zhang, Zewu; He, Man

    2014-08-15

    Optically active substituted polyacetylene@multiwalled carbon nanotubes (SPA@MWCNTs) nanohybrids were fabricated by wrapping helical SPA copolymers onto the surface of modified nanotubes through ester bonding linkage. SPA copolymer based on chiral phenylalanine and serine was pre-polymerized by a rhodium zwitterion catalyst in THF, and evidently proved to possess strong optical activity and adopt a predominately one-handed helical conformation. Various characterizations including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) demonstrated that the SPA had been covalently grafted onto the nanotubes without destroying their original graphite structure. The wrapped SPA was found to exhibit an enhancement in thermal stability and still maintained considerable optical activity after grafting. The infrared emissivity property of the nanohybrids at 8–14 μm was investigated in addition. The results indicated that the SPA@MWCNTs hybrid matrix could possess a much lower infrared emissivity value (ε=0.707) than raw MWCNTs, which might be due to synergistic effect of the unique helical conformation of optically active SPA and strengthened interfacial interaction between the organic polymers and inorganic nanoparticles. - Graphical abstract: Optically active SPA@MWCNTs nanohybrids with low infrared emissivity. - Highlights: • Synthesis of optically active SPA copolymer derived from serine and phenylalanine. • Preparation and characterization of optically active SPA@MWCNTs nanohybrids. • Application study of the SPA@MWCNTs nanohybrids (ε=0.707) in lowering the infrared emissivity.

  1. High-Contrast Imaging using Adaptive Optics for Extrasolar Planet Detection

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Julia Wilhelmsen [Univ. of California, Davis, CA (United States)

    2006-01-01

    Direct imaging of extrasolar planets is an important, but challenging, next step in planetary science. Most planets identified to date have been detected indirectly--not by emitted or reflected light but through the effect of the planet on the parent star. For example, radial velocity techniques measure the doppler shift in the spectrum of the star produced by the presence of a planet. Indirect techniques only probe about 15% of the orbital parameter space of our solar system. Direct methods would probe new parameter space, and the detected light can be analyzed spectroscopically, providing new information about detected planets. High contrast adaptive optics systems, also known as Extreme Adaptive Optics (ExAO), will require contrasts of between 10-6 and 10-7 at angles of 4-24 λ/D on an 8-m class telescope to image young Jupiter-like planets still warm with the heat of formation. Contrast is defined as the intensity ratio of the dark wings of the image, where a planet might be, to the bright core of the star. Such instruments will be technically challenging, requiring high order adaptive optics with > 2000 actuators and improved diffraction suppression. Contrast is ultimately limited by residual static wavefront errors, so an extrasolar planet imager will require wavefront control with an accuracy of better than 1 nm rms within the low- to mid-spatial frequency range. Laboratory demonstrations are critical to instrument development. The ExAO testbed at the Laboratory for Adaptive Optics was designed with low wavefront error and precision optical metrology, which is used to explore contrast limits and develop the technology needed for an extrasolar planet imager. A state-of-the-art, 1024-actuator micro-electrical-mechanical-systems (MEMS) deformable mirror was installed and characterized to provide active wavefront control and test this novel technology. I present 6.5 x 10-8 contrast measurements with a prolate shaped pupil and

  2. On the Evolution of High-Redshift Active Galactic Nuclei

    CERN Document Server

    Mao, Jirong

    2016-01-01

    We build a simple physical model to study the high-redshift active galactic Nucleus (AGN) evolution within the co-evolution framework of central black holes (BHs) and their host galaxies. The correlation between the circular velocity of a dark halo $V_c$ and the velocity dispersion of a galaxy $\\sigma$ is used to link the dark matter halo mass and BH mass. The dark matter halo mass function is converted to the BH mass function for any given redshift. The high-redshift optical AGN luminosity functions (LFs) are constructed. At $z\\sim 4$, the flattening feature is not shown at the faint end of the optical AGN LF. This is consistent with observational results. If the optical AGN LF at $z\\sim 6$ can be reproduced in the case in which central BHs have the Eddington-limited accretion, it is possible for the AGN lifetime to have a small value of $2\\times 10^5$ yrs. The X-ray AGN LFs and X-ray AGN number counts are also calculated at $2.03$, respectively, using the same parameters adopted in the calculation for the o...

  3. Dispersive and nonlinear effects in high-speed reconfigurable WDM optical fiber communication systems

    Science.gov (United States)

    Yu, Changyuan

    Chromatic dispersion, polarization mode dispersion (PMD) and nonlinear effects are important issues on the physical layer of high-speed reconfigurable WDM optical fiber communication systems. For beyond 10 Gbit/s optical fiber transmission system, it is essential that chromatic dispersion and PMD be well managed by dispersion monitoring and compensation. One the other hand, dispersive and nonlinear effects in optical fiber systems can also be beneficial and has applications on pulse management, all-optical signal processing and network function, which will be essential for high bite-rate optical networks and replacing the expensive optical-electrical-optical (O/E/O) conversion. In this Ph.D. dissertation, we present a detailed research on dispersive and nonlinear effects in high-speed optical communication systems. We have demonstrated: (i) A novel technique for optically compensating the PMD-induced RF power fading that occurs in single-sideband (SSB) subcarrier-multiplexed systems. By aligning the polarization states of the optical carrier and the SSB, RF power fading due to all orders of PMD can be completely compensated. (ii) Chromatic-dispersion-insensitive PMD monitoring by using a narrowband FBG notch filter to recover the RF clock power for 10Gb/s NRZ data, and apply it as a control signal for PMD compensation. (iii) Chirp-free high-speed optical pulse generation with a repetition rate of 160 GHz (which is four times of the frequency of the electrical clock) using a phase modulator and polarization maintaining (PM) fiber. (iv) Polarization-insensitive all-optical wavelength conversion based on four-wave mixing in dispersion-shifted fiber (DSF) with a fiber Bragg grating and a Faraday rotator mirror. (v) Width-tunable optical RZ pulse train generation based on four-wave mixing in highly-nonlinear fiber. By electrically tuning the delay between two pump pulse trains, the pulse-width of a generated pulse train is continuously tuned. (vi) A high-speed all-optical

  4. Optical sampling of ultrahigh bitrate signals using highly nonlinear chalcogenide planar waveguides or tapered fibers

    Science.gov (United States)

    Van Erps, Jürgen; Luan, Feng; Pelusi, Mark D.; Mägi, Eric; Iredale, Tim; Madden, Steve; Choi, Duk Yong; Bulla, Douglas A.; Luther-Davies, Barry; Thienpont, Hugo; Eggleton, Benjamin J.

    2010-06-01

    As the bit rates of optical networks increase, the ability of accurate monitoring of optical waveforms has become increasingly important. In recent years, optical sampling has emerged as a technique to perform time-resolved measurements of optical data signals at high data rates with a bandwidth that cannot be reached by conventional photodetectors and oscilloscopes. In an optical sampling system, the optical signal is sampled in the optical domain by a nonlinear optical sampling gate before the resulting samples are converted to an electrical signal. This avoids the need for high bandwidth electronics if the optical sampling gate is operated with a modest repetition frequency. In this paper, we present an optical sampling system using the optical Kerr effect in a highly nonlinear chalcogenide device, enabling combined capability for femtosecond resolution and broadband signal wavelength tunability. A temporal resolution 450-fs is achieved using four-wave mixing (FWM) in dispersion-engineered chalcogenide waveguides: on one hand a 7-cm long planar waveguide (integrated on a photonic chip) and on the other hand a 5-cm long tapered fiber. The use of a short length, dispersion-shifted waveguide with ultrahigh nonlinearity (10000/W/km) enables high-resolution optical sampling without the detrimental effect of chromatic dispersion on the temporal distortion of the signal and sampling pulses, as well as their phase mismatch (which in turn would degrade the FWM efficiency and the sensitivity of the measurement). Using these chalcogenide devices, we successfully monitor a 640-Gb/s optical time-division multiplexing (OTDM) datastream, showcasing its potential for monitoring of signals at bitrates approaching and beyond Tb/s. We compare the advantages and disadvantages of both approaches and discuss fundamental limitations as well as potential improvements.

  5. Structural, optical and photo-catalytic activity of nanocrystalline NiO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Al-Ghamdi, Attieh A. [Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Abdel-wahab, M. Sh., E-mail: mshabaan90@yahoo.com [Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia); Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef (Egypt); Farghali, A.A. [Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences, Beni-Suef University, Beni-Suef (Egypt); Chemistry Department, Faculty of Science, Beni-Suef University, Beni-Suef (Egypt); Hasan, P.M.Z. [Center of Nanotechnology, King Abdulaziz University, Jeddah (Saudi Arabia)

    2016-03-15

    Highlights: • Synthesis of nanocrystalline NiO thin films with different thicknesses using DC magnetron sputtering technique. • Effect of film thickness and particle size on photo-catalytic degradation of methyl green dye under UV light was studied. • The deposited NiO thin films are efficient, stable and possess high photo-catalytic activity upon reuse. - Abstract: Physical deposition of nanocrystalline nickel oxide (NiO) thin films with different thickness 30, 50 and 80 nm have been done on glass substrate by DC magnetron sputtering technique and varying the deposition time from 600, 900 to 1200 s. The results of surface morphology and optical characterization of these films obtained using different characterization techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), photoluminescence (PL) and UV–vis spectrophotometry provide important information like formation of distinct nanostructures in different films and its effect on their optical band gap which has decreased from 3.74 to 3.37 eV as the film thickness increases. Most importantly these films have shown very high stability and a specialty to be recycled without much loss of their photo-catalytic activity, when tested as photo-catalysts for the degradation of methyl green dye (MG) from the wastewater under the exposure of 18 W energy of UV lamp.

  6. High-sensitive Optical Pulse-Shape Characterization using a Beating-Contrast-Measurement Technique

    CERN Document Server

    Roncin, Vincent; Millaud, Audrey; Cramer, Romain; Jaouën, Yves; Simon, Jean-Claude

    2014-01-01

    Ultrahigh-speed optical transmission technology, such as optical time domain multiplexing or optical signal processing is a key point for increasing the communication capacity. The system performances are strongly related to pulse properties. We present an original method dedicated to short pulse-shape characterization with high repetition rate using standard optical telecommunications equipments. Its principle is based on temporal measurement of the contrast produced by the beating of two delayed optical pulses in a high bandwidth photo detector. This technique returns firstly reliable information on the pulse-shape, such as pulse width, shape and pedestal. Simulation and experimental results evaluate the high-sensitivity and the high-resolution of the technique allowing the measurement of pulse extinction ratio up to 20 dB with typical timing resolution of about 100 fs. The compatibility of the technique with high repetition rate pulse measurement offers an efficient tool for short pulse analysis.

  7. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  8. ALL OPTICAL IMPLEMENTATION OF HIGH SPEED AND LOW POWER REVERSIBLE FULL ADDER USING SEMICONDUCTOR OPTICAL AMPLIFIER BASED MACH-ZEHNDER INTERFEROMETER

    Directory of Open Access Journals (Sweden)

    R. M. Bommi

    2014-01-01

    Full Text Available In the recent years reversible logic design has promising applications in low power computing, optical computing, quantum computing. VLSI design mainly concentrates on low power logic circuit design. In the present scenario researchers have made implementations of reversible logic gates in optical domain for its low energy consumption and high speed. This study is all about designing a reversible Full adder using combination of all optical Toffoli and all optical TNOR and to compare it with the Full adder designed using all optical Toffoli gate in terms of optical cost. All optical TNOR gate can work as a replacement of existing NAND based All optical Toffoli Gate (TG. The gates are designed using Mach-Zehnder Interferometer (MZI based optical switch. The proposed system is developed with the basic of reversibility to design all optical full Adder implemented with CMOS transistors. The design is efficient in terms of both architecture and in power consumption.

  9. Fabrication and characterization of cerium-doped terbium gallium garnet with high magneto-optical properties.

    Science.gov (United States)

    Chen, Zhe; Hang, Yin; Yang, Lei; Wang, Jun; Wang, Xiangyong; Hong, Jiaqi; Zhang, Peixiong; Shi, Chunjun; Wang, Yaqi

    2015-03-01

    High optical quality (Tb((1-x))Ce(x))₃Ga₅O₁₂ (TCGG) single crystal has been grown by the Czochralski method. The optical and magneto-optical properties of the TCGG are analyzed in detail and the Verdet constant (V) of TCGG is compared with that of undoped terbium gallium garnet (TGG) crystal. TCGG presents a very high transmittance, particularly in the visible-near infrared (VIS-NIR) region, and its V is obviously larger than that of TGG in the VIS-NIR region. The figure of merit and optical features point out the superior characteristics of TCGG with respect to TGG.

  10. Active photonic sensor communication cable for field application of optical data and power transmission

    Science.gov (United States)

    Suthau, Eike; Rieske, Ralf; Zerna, Thomas

    2014-10-01

    Omitting electrically conducting wires for sensor communication and power supply promises protection for sensor systems and monitored structures against lightning or high voltages, prevention of explosion hazards, and reduction of susceptibility to tampering. The ability to photonically power remote systems opens up the full range of electrical sensors. Power-over-fiber is an attractive option in electromagnetically sensitive environments, particularly for longterm, maintenance-free applications. It can deliver uninterrupted power sufficient for elaborate sensors, data processing or even actuators alongside continuous high speed data communication for remote sensor application. This paper proposes an active photonic sensor communication system, which combines the advantages of optical data links in terms of immunity to electromagnetic interference (EMI), high bandwidth, hardiness against tampering or eavesdropping, and low cable weight with the robustness one has come to expect from industrial or military electrical connectors. An application specific integrated circuit (ASIC) is presented that implements a closed-loop regulation of the sensor power supply to guarantee continuous, reliable data communications while maintaining a highly efficient, adaptive sensor supply scheme. It is demonstrated that the resulting novel photonic sensor communication cable can handle sensors and actuators differing orders of magnitude with respect to power consumption. The miniaturization of the electro-optical converters and driving electronics is as important to the presented development as the energy efficiency of the detached, optically powered sensor node. For this reason, a novel photonic packaging technology based on wafer-level assembly of the laser power converters by means of passive alignment will be disclosed in this paper.

  11. Ultra-fast coherent optical system for active remote sensing applications

    Science.gov (United States)

    Datta, Shubhashish; Becker, Don; Joshi, Abhay; Howard, Roy

    2008-04-01

    Active optical remote sensing has numerous applications including battlefield target recognition and tracking, atmospheric monitoring, structural monitoring, collision avoidance systems, and terrestrial mapping. The maximum propagation distance in LIDAR sensors is limited by the signal attenuation. Sensor range could be improved by increasing the transmitted pulse energy, at the expense of reduced resolution and information bandwidth. Coherent detection can operate at low optical power levels without sacrificing sensor bandwidth. Utilizing a high power LO laser to increase the receiver gain, coherent systems provide shot noise-limited gain thereby increasing the sensing range. To fully exploit high LO powers without incurring performance penalties due to the RIN of the LO, high power handling balanced photodiodes are used. The coherent system has superior dynamic range, bandwidth, and noise performance than small-signal APD-based systems. Coherent detection is a linear process that is sensitive to the amplitude, phase and polarization of the received signal. Therefore, Doppler shifts and vibration signatures can be easily recovered. RF adaptive filtering following photodetection enables channel equalization, atmospheric turbulence compensation, and efficient background light filtering. We demonstrate a coherent optical transmission system using 15mA high power handling balanced photodetectors. This system has an IF linewidth <1Hz, employing a proprietary phase locked loop design. Data is presented for 100ps pulsed transmission. We have demonstrated amplitude and phase modulated 10Gb/s communication links with sensitivities of 132 and 72 photons per bit respectively. Investigations into system performance in the presence of laboratory induced atmospheric turbulence are shown.

  12. High confinement, high yield Si3N4 waveguides for nonlinear optical application

    CERN Document Server

    Epping, Jörn P; Mateman, Richard; Leinse, Arne; Heideman, René G; van Rees, Albert; van der Slot, Peter J M; Lee, Chris J; Boller, Klaus-J

    2014-01-01

    In this paper we present a novel fabrication technique for silicon nitride (Si3N4) waveguides with a thickness of up to 900 nm, which are suitable for nonlinear optical applications. The fabrication method is based on etching trenches in thermally oxidized silicon and filling the trenches with Si3N4. Using this technique no stress-induced cracks in the Si3N4 layer were observed resulting in a high yield of devices on the wafer. The propagation losses of the obtained waveguides were measured to be as low as 0.4 dB/cm at a wavelength of around 1550 nm.

  13. High Resolution Time Series Observations of Bio-optical and Physical Variability in the Arabian Sea

    Science.gov (United States)

    1997-09-30

    Dynamics Program activities in the region. The Arabian Sea presents a very unique environment for study of bio -optical and physical processes and their...and biology of the upper layer. Thus, dynamical ranges in measured properties are great, enabling us to apply and test time dependent interdisciplinary models relevant to bio -optical properties and carbon fluxes.

  14. Advanced Components For Fiber-Optical Systems

    Science.gov (United States)

    Depaula, Ramon; Stowe, David W.

    1989-01-01

    Paper reviews statuses of some advanced passive and active optical components for use with optical fibers. Emphasis on highly birefringent components controling polarization, because control of polarization critical in applications as fiber-optical gyroscopes, interferometric sensors, and coherent communications.

  15. Maintaining high-Q in an optical microresonator coated with high-aspect-ratio gold nanorods

    Science.gov (United States)

    Ganta, D.; Dale, E. B.; Rosenberger, A. T.

    2013-10-01

    We report methods to coat fused-silica microresonators with solution-grown high-aspect-ratio (AR) gold nanorods (NRs). Microresonators coated using our method maintain an optical quality factor (Q) greater than 107 after coating. The more successful method involves silanization of the surface of the microresonator with 3-mercaptopropylmethyldimethoxysilane (MPMDMS), to enable the adhesion of gold NRs. The high-AR NR-coated microresonator combines the field enhancement of localized surface plasmon resonances with the cavity-enhanced evanescent components of high-Q whispering-gallery modes, making it useful for plasmonic sensing applications in the infrared. By coating with NRs having a different aspect ratio, the enhancement regime can be selected within a wide range of wavelengths.

  16. Estimation of optical parameters of highly scattering materials by time-of-flight spectroscopy

    Science.gov (United States)

    Plucinski, Jerzy

    2004-07-01

    Optical measurement methods are indispensable tool in biomedical research, providing invaluable information on optical properties of biological tissues. However, the application of these techniques is a big challenge, as most tissues are highly scattering materials whose optical properties cannot be measured in a straightforward way, due to multiple scattering of photons. Therefore, new optical measurement techniques and methods for highly scattering media are being developed to address this problem. One of the very promising techniques is time-of-flight spectroscopy. The paper presents problems encountered in reconstruction of basic optical parameters of tissues or other highly scattering materials from optical time-of-flight spectroscopy measurement data. To estimate the reconstruction accuracy of optical parameters (i.e. absorption coefficient, scattering coefficient, anisotropy factor and refractive index) the test data were generated by a computer program simulating light propagation in highly scattering material by Monte Carlo method. Following, a set of computer programs based on diffusion equation and optimization algorithms such as simplex method and genetic method were used to reconstruct optical parameters from the test data. Finally, by comparing reconstructed optical parameters with those used for generation of the test data, the accuracy of reconstructing algorithms it was estimated.

  17. Fibre and components induced limitations in high capacity optical networks

    DEFF Research Database (Denmark)

    Peucheret, Christophe

    2003-01-01

    measurement techniques are first reviewed, and the limitations of the commonly used phase-shift technique is discussed. Additionally, an alternative method which enables the direct determination of small dispersion values in the pass-band of optical filters is proposed. Available optical filter technologies...... km pre-compensated spans. Passive pre distortion at the transmitter is shown to significantly improve the reach of the systems. Based on the experimental results, transparent domains with a diameter of the order of 1000 km can be realised, thus demonstrating the applicability of the optimisation...

  18. Opportunities for optics within tomorrow’s high-tech

    DEFF Research Database (Denmark)

    Hanson, Steen Grüner

    The use of miniaturized optical sensors as input devices based on speckle phenomena will be discussed alongside with some considerations on the path to industrial implementation. Based on two examples from the field of cursor control systems, the future opportunities for dissemination into indust......The use of miniaturized optical sensors as input devices based on speckle phenomena will be discussed alongside with some considerations on the path to industrial implementation. Based on two examples from the field of cursor control systems, the future opportunities for dissemination...... price will be dealt with. Besides, some general remarks on my observations on bringing ideas from the lab into commercial products will be offered....

  19. Active fibre optic splitter for the CMS RPC detector

    Energy Technology Data Exchange (ETDEWEB)

    Banzuzi, Kukka [Helsinki Institute of Physics, University of Helsinki, P.O. Box 64, Gustaf Haellstroemin katu 2, FIN-00014 (Finland)]. E-mail: Kukka.Banzuzi@oxinst.fi; Iskanius, Matti [Lappeenranta University of Technology, P.O, Box 20, Lapprenranta, FIN-53851 (Finland); Karjalainen, Ahti [Lappeenranta University of Technology, P.O, Box 20, Lapprenranta, FIN-53851 (Finland); Tuuva, Tuure [Lappeenranta University of Technology, P.O, Box 20, Lapprenranta, FIN-53851 (Finland)

    2006-09-15

    An electronics module has been designed and tested for the CMS RPC detector readout. The module consists of twelve sub-blocks, each of which receives an optical signal at 1.6 GHz, converts it into electronic form for the splitting process and sends it forth to two or four destinations in optical form. It is a critical part in the trigger system of the experiment. Details of the design are presented, as well as test results confirming that the splitter fulfils all system requirements.

  20. Active optics: deformable mirrors with a minimum number of actuators

    CERN Document Server

    Laslandes, Marie; Ferrari, Marc; 10.2971/jeos.2012.12036

    2012-01-01

    We present two concepts of deformable mirror to compensate for first order optical aberrations. Deformation systems are designed using both elasticity theory and Finite Element Analysis in order to minimize the number of actuators. Starting from instrument specifications, we explain the methodology to design dedicated deformable mirrors. The work presented here leads to correcting devices optimized for specific functions. The Variable Off-Axis paraboLA concept is a 3-actuators, 3-modes system able to generate independently Focus, Astigmatism and Coma. The Correcting Optimized Mirror with a Single Actuator is a 1-actuator system able to generate a given combination of optical aberrations.