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Sample records for acousto optic modulators

  1. Fiber Acousto-Electro-Optic Modulator

    Anen; Jiang

    2003-01-01

    A new kind of fiber acousto-electro-optic modulator is made by using Lithium Niobate crystal. This kind of modulator can be used in fiber communication, and its center frequency can be changed by directed current voltages.

  2. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    Tadesse, Semere A; Liu, Qiyu; Li, Mo

    2015-01-01

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable new acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with periods as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in the new devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a novel scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.

  3. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    Tadesse, Semere A. [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States); School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Li, Huan; Liu, Qiyu; Li, Mo, E-mail: moli@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2015-11-16

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored.

  4. Acousto-optic modulation of a photonic crystal nanocavity with Lamb waves in microwave K band

    Integrating nanoscale electromechanical transducers and nanophotonic devices potentially can enable acousto-optic devices to reach unprecedented high frequencies and modulation efficiency. Here, we demonstrate acousto-optic modulation of a photonic crystal nanocavity using Lamb waves with frequency up to 19 GHz, reaching the microwave K band. The devices are fabricated in suspended aluminum nitride membrane. Excitation of acoustic waves is achieved with interdigital transducers with period as small as 300 nm. Confining both acoustic wave and optical wave within the thickness of the membrane leads to improved acousto-optic modulation efficiency in these devices than that obtained in previous surface acoustic wave devices. Our system demonstrates a scalable optomechanical platform where strong acousto-optic coupling between cavity-confined photons and high frequency traveling phonons can be explored

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

    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.

  6. Different Plastic Materials Based Acousto-optic Modulators (AOMs Design Considerations for Fast Switching Applications

    Ahmed Nabih Zaki Rashed

    2012-09-01

    Full Text Available An acousto-optic modulator (AOM allows to diffract a laser beam going through a crystal from the incidence angle (order 0 to another angle (order 1. The diffracted beam intensity depends on the radio frequency (RF power applied to the device while the output angle depends on the material but is also proportional to the laser wavelength and to the RF drive frequency. When only intensity modulation is required, the driver frequency is fixed (thus the output beam angle and the intensity is controlled, in analog or digital mode, by controlling the applied RF power. Long term stability and reliability are required from the driving electronics. This paper has presented the best candidate selected polymeric acousto-optic materials based AOM for upgrading speed response and transmission performance characteristics. These materials are common materials for acousto-optic devices such as polymethyl-methacrylate (PMMA, polycarbonate (PC, polystyrene (PS, and polysulfone (PSF. As well as we have deeply investigated the important transmission characteristics of acousto optic modulators such as transmission performance efficiency, transmission bit rate, diffraction angle and efficiency, transient speed response, signal transmission quality, bit error rate (BER and modulation bandwidth under wide range of the affecting parameters for different selected acousto optic materials to be the major of interest.

  7. Modern optical signal processing experiments demonstrating intensity and pulse-width modulation using an acousto-optic modulator

    Poon, Ting-Chung; McNeill, Mark D.; Moore, Daniel J.

    1997-09-01

    Two experiments are presented to introduce undergraduate students in electrical engineering or physics to modern optical signal processing. Both experiments use an acousto-optic (AO) Bragg cell together with additional electronics to modify the intensity of a laser beam. Specifically, we show how an AO feedback system operating in the Bragg regime can be configured to produce amplitude modulated (AM) and pulse-width modulated optical signals. The basic components of the AO feedback system include a laser, an AO Bragg cell, an electronic AM modulator, a photodetector, an amplifier, and an electronic adder. Except for the laser, the AM modulator, and the Bragg cell, each of these components can be constructed with low cost electronics. A tutorial outlining the principles of acousto-optics is included to provide sufficient understanding of the Bragg cell. The project described in the paper has been used as a demonstration for junior- and senior-level undergraduate students in electrical engineering communications and optics classes.

  8. Acousto-optic properties of GexS100–x glasses and acousto-optic modulator on their basis

    Bletskan D. I.

    2014-12-01

    Full Text Available The investigation of acousto-optic properties of GexS100–x glasses, which had shown that they are perspective lightsoundwire material for manufacturing of acousto-optic devices for controlling the laser radiation in the visible spectral region was performed. Taking into account the technological conditions for synthesis of glasses with optical quality the two optimal compositions, Ge30S70 and Ge25S75, were proposed for fabrication of optical-acoustic modulator. These compositions possess the high optical perfection and transmission in the spectral range of 0.4—11 μm, the moderate optical absorption of 2—3 dB/cm, their acoustic quality factor ~100 times exceeds those of quartz. The construction and main parameters of the acousto-optic modulator based on Ge30S70 and Ge25S75 glasses as lightsoundwire material and the converter is a plate of lithium niobate single crystal were described. In Bragg diversion mode the modulator has the maximum bandwidth of the modulating frequencies — 10 MHz, the diffraction efficiency — 40%, the speed — near 80 nanoseconds. It is also important to note that the effective modulation is obtained with the low power (40 mW controlled electrical signal, which facilitates a thermal mode of the modulator and allows working without the forced cooling of the modulation element.

  9. Tandem-pulsed acousto-optics: an analytical framework of modulated high-contrast speckle patterns

    Recently we presented acousto-optic (AO) probing of scattering media using addition or subtraction of speckle patterns due to tandem nanosecond pulses. Here we present a theoretical framework for ideal (polarized, noise-free) speckle patterns with unity contrast that links ultrasound-induced optical phase modulation, the fraction of light that is tagged by ultrasound, speckle contrast, mean square difference of speckle patterns and the contrast of the summation of speckle patterns acquired at different ultrasound phases. We derive the important relations from basic assumptions and definitions, and then validate them with simulations. For ultrasound-generated phase modulation angles below 0.7 rad (assuming uniform modulation), we are now able to relate speckle pattern statistics to the acousto-optic phase modulation. Hence our theory allows quantifying speckle observations in terms of ultrasonically tagged fractions of light for near-unity-contrast speckle patterns. (paper)

  10. Laser communication system with acousto-optic tracking and modulation: experimental study

    Nikulin, Vladimir V.; Sofka, Jozef

    2009-12-01

    Laser communication systems are highly preferred for broadband applications. This technology uses higher regions of the spectrum, and offers unsurpassed throughput, information security, reduced weight and size of the components, and power savings. Unfortunately, small beam divergence requires precise positioning, which becomes very critical at high data rates. Complex motion patterns of the communicating platforms, vibrations, and atmospheric effects cause significant signal losses due to the pointing errors, beam wander, and other higher order effects. Mitigation of those effects is achieved by fast tracking, which can be successfully combined with signal modulation. In this work, we focus on the application of acousto-optic technology and its effect on communication performance. We present experimental results for a laser communication link affected by pointing distortions. These distortions are generated to emulate specific operation environments with particular spectral characteristics. The acousto-optic technology is used to build an agile tracking system combined with signal modulation in the same device to assure maximum signal reception, in spite of the harsh operational conditions. The received communication signal is recorded and statistically analyzed to calculate the bit error rates. This work presents synthesis of a tracking system and experimental results characterizing the communication performance under uncompensated pointing disturbance and with tracking.

  11. Emission spectroscopy of laser ablation plasma with time gating by acousto-optic modulator

    The capability of acousto-optic modulator (AOM) to perform time-gated measurements for laser ablation plasma spectroscopy has been examined. Especially, we focused on the capability of the ''AOM gating'' to exclude the continuum and extremely broadened spectra usually observed immediately after the laser ablation. Final goal of the use of the AOM is to achieve considerable downsizing of the system for in situ and on-site analyses. In the present paper, it is shown that narrow and clear spectral lines can be obtained with the AOM gating even if the target is submerged in water. Also, application of this technique to the targets in air is demonstrated. It has been revealed that the AOM gating is fast enough to exclude the continuum and broadened lines, while effectively acquiring sufficiently narrow atomic lines lasting slightly longer than the continuum.

  12. Post-Flight Test Results of Acousto-Optic Modulator Devices Subjected to Space Exposure

    Prasad, Narasimha S.; Trivedi, Sudhir; Rosemeier, Jolanta; Diestler, Mark

    2014-01-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 module was brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in a space environment for more than one and a half years included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the results of performance testing of a laser diode module sent by NASA Langley Research Center on MISSE 7 mission will be discussed. This paper will present the comparison of pre-flight and post-flight performance of two different COTS acousto-optic modulator (AOM) devices. Post-flight measurements indicate that these two devices did not undergo any significant performance degradation.

  13. Post-flight test results of acousto-optic modulator devices subjected to space exposure

    Prasad, Narasimha S.; Trivedi, Sudhir; Rosemeier, Jolanta; Diestler, Mark

    2014-09-01

    The objective of the Materials International Space Station Experiment (MISSE) is to study the performance of novel materials when subjected to the synergistic effects of the harsh space environment for several months. MISSE missions provide an opportunity for developing space qualifiable materials. Several laser and lidar components were sent by NASA Langley Research Center (LaRC) as a part of the MISSE 7 mission. The MISSE 7 module was transported to the international space station (ISS) via STS 129 mission that was launched on Nov 16, 2009. Later, the MISSE 7 modulewas brought back to the earth via the STS 134 that landed on June 1, 2011. The MISSE 7 module that was subjected to exposure in space environment for more than one and a half year included fiber laser, solid-state laser gain materials, detectors, and semiconductor laser diode. Performance testing of these components is now progressing. In this paper, the results of performance testing of a laser diode module sent by NASA Langley Research Center on MISSE 7 mission will be discussed. This paper will present the comparison of pre-flight and post-flight performance of two different COTS acousto-optic modulator devices. Post-flight measurements indicate that these two devices did not undergo any significant performance degradation.

  14. LIGHT MODULATION: Quasi-collinear tunable acousto-optic paratellurite crystal filters for wavelength division multiplexing and optical channel selection

    Molchanov, V. Ya; Voloshinov, V. B.; Makarov, O. Yu

    2009-04-01

    Quasi-collinear acousto-optic interaction is studied in acoustically and optically anisotropic paratellurite crystals. The possible applications of this interaction in acousto-optic tunable filters with a high spectral resolution are discussed. Different modifications of devices are compared and variants of devices intended for processing light beams and selection of light signals in fibreoptic communication systems with wavelength division multiplexing (WDM) at λ simeq 1550 nm are considered.

  15. Hyper-spectral modulation fluorescent imaging using double acousto-optical tunable filter based on TeO2-crystals

    We have proposed a method for hyper-spectral fluorescent imaging based on acousto-optical filtering. The object of interest was pumped using ultraviolet radiation of mercury lamp equipped with monochromatic excitation filter with the window of transparency centered at 365 nm. Double TeO2-based acousto-optical filter, tunable in range from 430 to 780 nm and having 2 nm bandwidth of spectral transparency, was used in order to detect quasimonochromatic images of object fluorescence. Modulating of ultraviolet pump intensity was used in order to reduce an impact of non-fluorescent background on the sample fluorescent imaging. The technique for signal-to-noise ratio improvement, based on fluorescence intensity estimation via digital processing of modulated video sequence of fluorescent object, was introduced. We have implemented the proposed technique for the test sample studying and we have discussed its possible applications

  16. Acousto-Optic Devices For Use In Radio Frequency Target Simulators

    Kirchner, Ernst K.

    1980-01-01

    Acousto-optic devices have been analyzed and developed for use as modulators, filters and correlators, and in spectrum analyzers. The ability of the acousto-optic unit to amplitude-modulate, frequency-modulate, and deflect laser beams, makes them suitable for these applications. The various signal processing and control functions provided by the acousto-optic devices are optimized by controlling the ratio of divergence angles of the optical beam and the acoustic beam in the acousto-optic interaction region. Another application of acousto-optic devices is to simulate moving targets to test fuzing altimeters and active missile control systems. The frequency modulation, amplitude modulation, and deflection properties of acousto-optic components are all utilized in a single acousto-optic unit to provide the variable range and Doppler simulation. Development of a suitable acousto-optic component for this simulation application is described, as is a description of a simulator employing this acousto-optic device.

  17. Investigation of noise in Lightwave Synthesized Frequency Sweeper seeded LIDAR anemometers from leakage through the Acousto Optic Modulators

    Pedersen, Anders Tegtmeier; Lindelöw, Per Jonas Petter

    2009-01-01

    Train (FSPT) modulated lidars the leakage will give rise to rapidly growing noise in the bins which corresponds to the signal from low radial wind velocities. It is likely that noise canceling techniques similar to those used for RIN removal has to be deployed for measurements of low wind velocities.......Lightwave Synthesized Frequency Sweepers (LSFS) have potential use as lightsources in lidar anemometers. In this paper noise due to leakage in the acousto optic modulators in an LSFS is investigated. Theoretical expressions describing the build-up of noise in the LSFS due to leakage are derived...

  18. An acousto-optic beamformer

    Torras Rosell, Antoni; Barrera Figueroa, Salvador; Jacobsen, Finn

    2012-01-01

    of transducers, which makes beamforming methods vulnerable to spatial aliasing above a certain frequency. The present work uses the acousto-optic effect, i.e., the interaction between sound and light, to localize sound sources in a plane. The use of a beam of light as the sensing element is...... equivalent to a continuous line aperture with an infinite number of microphones. This makes the proposed acousto-optic beamformer immune to spatial aliasing. This unique feature is illustrated by means of simulations and experimental results within the entire audible frequency range. For ease of comparison...

  19. The Experimental Study on Acousto-optic Modulation Based on Single-mode Fiber Fused Coupler

    Liu Guoxiang; Hu Li; Ye Kunzhen; Lin Weigan

    2002-01-01

    In-line acoustic-optic (AO) modulation experiments were demonstrated based on the acoustic-optic effect in optical fiber fused taper couplers.About 73%,64%,and 61% modulation have been achieved at frequencies of 0.169 MHz,0.367 MHz and 0.521 MHz with an electrical driving power less than 10 mW,respectively.

  20. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    Gómez Colín, R.; García Juárez, A.; Zaldívar Huerta, I. E.; Marquina, A. Vera; García Delgado, L. A.; Leal Cruz, A. L.; Gómez Fuentes, R.

    2016-03-01

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade.

  1. An experimental distribution of analog and digital information in a hybrid wireless visible light communication system based on acousto-optic modulation and sinusoidal gratings

    In this paper we propose a photonic architecture as an alternative tool to distribute point to multipoint analog and digital information over a hybrid wireless visible optical communication system. The experimental set-up is composed of a red laser pointer, an acousto-optic modulator, a sinusoidal grating and a photo-detector array. By using a simple and variable interferometric system, diffraction gratings with different spatial frequencies are generated and recorded on a photoemulsion which is composed of vanilla with dichromate gelatin. Analog video and digital information are first transmitted and recovered over a wireless communication system using a microwave carrier at 4.52 GHz which is generated by distributed feedback lasers operating in the low laser threshold current region. Separately, the recovered video information and digital data are combined with a radio frequency signal of 80 MHz, obtaining a subcarrier of information that is imposed on the optical carrier of the pointer laser using an acousto-optic modulator which is operated with an angle of incident light that satisfies the Bragg condition. The modulated optical carrier is sent to a sinusoidal grating, the diffraction pattern is photo-detected using an array of PIN photo-detectors. The use of sinusoidal gratings with acousto-optic modulators allows that number of channels to be increased when both components are placed in cascade. (paper)

  2. LIGHT MODULATION: Wide-aperture diffraction of unpolarised radiation in a system of two acousto-optic filters

    Magdich, L. N.; Yushkov, K. B.; Voloshinov, V. B.

    2009-04-01

    Light diffraction is studied in two tandem acousto-optic cells filtering unpolarised radiation with a wide angular spectrum. It is shown that the side lobes of the ultrasonic radiation pattern of a piezoelectric transducer produce side diffraction intensity maxima at the output of the system consisting of two filters. Diffraction in paratellurite filters is studied experimentally at 1.06 μm.

  3. Laser frequency stabilisation by the Pound - Drever - Hall method using an acousto-optic phase modulator operating in the pure Raman - Nath diffraction regime

    Frequency stabilisation of diode laser radiation has been implemented by the Pound - Drever - Hall method using a new acousto-optic phase modulator, operating in the pure Raman - Nath diffraction regime. It is experimentally shown that, as in the case of saturated-absorption spectroscopy in atomic vapour, the spatial divergence of the frequency-modulated output spectrum of this modulator does not interfere with obtaining error signals by means of heterodyne frequency-modulation spectroscopy with a frequency discriminator based on a high-Q Fabry - Perot cavity with finesse of several tens of thousands.

  4. Cavity dumping of neodymium-doped fibre lasers using acousto-optic modulator

    Abdulhalim, I.; Pannell, C.N.; Jedrzejewski, K.P.; Taylor, E.R.

    1994-01-01

    We report high-repetition-rate pulses obtained by cavity dumping of a neodymium-doped phosphate glass fibre laser operating at 1053 nm using a specially constructed acoustooptic modulator. With 27 mW absorbed pump power at 812 nm we obtained stable trains of output pulses with repetition rate in the range 0.5 to 8MHz having corresponding pulse widths in the range 127 to 19 ns without significant sacrifice in the average output power of 8 mW.

  5. Acousto-optic Extensometer for Bolts

    Maram, J.; Kuhr, G.

    1985-01-01

    Bolt torque or tension deduced from non contacting measurements. Pulsed Laser induces shockwave in bolthead while continuous-wave acousto-optic detector monitors distortion produced by shock. Shock travel time measured to determine bolt length. Solid-state position detector relatively inexpensive and keeps down cost of extensometer.

  6. Isolation of Integrated Optical Acousto-Optic Switch

    XIAO Li-Feng; LIU Ying; WANG Wei-Peng; GENG Fan

    2006-01-01

    @@ Isolation of a new structured acousto-optic switch based on an integrated optical polarization-independent quasicollinear acousto-optic tunable filter is studied in detail. The factors that influence the isolation of the optical switch are analysed, the expressions of the isolation are educed, and the isolation of the device is measured in experiment. It is found that the isolation mainly depends on the TE/TM mode intensity ratio, the mode-splitter extinction rate, and the conversion efficiency.

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

    Dühring, Maria Bayard

    using these new types of SAWs compared to using the waves generated by the conventional interdigital transducer with thin electrodes. Thus, this indicates a way to improve acousto-optical interaction for integrated modulators, which have important applications such as optical phase shifters....... 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...

  8. High-peak-power sub-nanosecond intracavity KTiOPO4 optical parametric oscillator pumped by a dual-loss modulated laser with acousto-optic modulator and single-walled carbon nanotube

    Qiao, Junpeng; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Guiqiu; Li, Dechun; Li, Tao; Qiao, Wenchao; Lu, Jianren; Wang, Yonggang; Chu, Hongwei; Luan, Chao

    2016-08-01

    A high-peak-power low-repetition-rate sub-nanosecond intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a doubly Q-switched and mode-locked (QML) YVO4/Nd:YVO4 laser with an acousto-optic modulator (AOM) and a single-walled carbon nanotube saturable absorber (SWCNT-SA) has been demonstrated. A maximum output power of 373 mW at a signal wavelength of 1570 nm was obtained. The smallest pulse width, highest pulse energy, and greatest peak power of mode-locking pulses were estimated to be 119 ps, 124 µJ, and 1.04 MW, respectively, under a maximum incident pump power of 8.3 W and an AOM repetition rate of 2 kHz. This OPO operation paves a simple way to produce eye-safe laser sources at 1570 nm with low repetition rates, small pulse widths, and high peak powers.

  9. Polarization-independent operation of an acousto-optical device at the transmit end of a single-laser transmission system using self-heterodyning

    Olivier, L.; Rocks, M.

    1991-03-01

    This paper describes the way in which a new integrated acousto-optical LiNbO 3 device combining the three functions of an electro-optical phase modulator, an acousto-optical TE/TM or TM/TE mode converter and an acousto-optical frequency shifter can be operated in a polarization-independent manner as a transmitter unit in a single-laser transmission system using self-heterodyning.

  10. Experimental demonstration of remote, passive acousto-optic sensing.

    Antonelli, Lynn; Blackmon, Fletcher

    2004-12-01

    Passively detecting underwater sound from the air can allow aircraft and surface vessels to monitor the underwater acoustic environment. Experimental research into an optical hydrophone is being conducted for remote, aerial detection of underwater sound. A laser beam is directed onto the water surface to measure the velocity of the vibrations occurring as the underwater acoustic signal reaches the water surface. The acoustically generated surface vibrations modulate the phase of the laser beam. Sound detection occurs when the laser is reflected back towards the sensor. Therefore, laser alignment on the specularly reflecting water surface is critical. As the water surface moves, the laser beam is reflected away from the photodetector and no signal is obtained. One option to mitigate this problem is to continually steer the laser onto a spot on the water surface that provides a direct back-reflection. Results are presented from a laboratory test that investigates the feasibility of the acousto-optic sensor detection on hydrostatic and hydrodynamic surfaces using a laser Doppler vibrometer in combination with a laser-based, surface normal glint tracker for remotely detecting underwater sound. This paper outlines the acousto-optic sensor and tracker concepts and presents experimental results comparing sensor operation under various sea surface conditions. PMID:15658691

  11. Ultrafast acousto-optic mode conversion in optically birefringent ferroelectrics.

    Lejman, Mariusz; Vaudel, Gwenaelle; Infante, Ingrid C; Chaban, Ievgeniia; Pezeril, Thomas; Edely, Mathieu; Nataf, Guillaume F; Guennou, Mael; Kreisel, Jens; Gusev, Vitalyi E; Dkhil, Brahim; Ruello, Pascal

    2016-01-01

    The ability to generate efficient giga-terahertz coherent acoustic phonons with femtosecond laser makes acousto-optics a promising candidate for ultrafast light processing, which faces electronic device limits intrinsic to complementary metal oxide semiconductor technology. Modern acousto-optic devices, including optical mode conversion process between ordinary and extraordinary light waves (and vice versa), remain limited to the megahertz range. Here, using coherent acoustic waves generated at tens of gigahertz frequency by a femtosecond laser pulse, we reveal the mode conversion process and show its efficiency in ferroelectric materials such as BiFeO3 and LiNbO3. Further to the experimental evidence, we provide a complete theoretical support to this all-optical ultrafast mechanism mediated by acousto-optic interaction. By allowing the manipulation of light polarization with gigahertz coherent acoustic phonons, our results provide a novel route for the development of next-generation photonic-based devices and highlight new capabilities in using ferroelectrics in modern photonics. PMID:27492493

  12. Optical phase noise engineering via acousto-optic interaction and its interferometric applications

    Satapathy, Nandan; Bannerjee, Sourish; Ramachandran, Hema

    2013-01-01

    We exercise rapid and fine control over the phase of light by transferring digitally gen- erated phase jumps from radio frequency (rf) electrical signals onto light by means of acousto-optic interaction. By tailoring the statistics of phase jumps in the electrical signal and thereby engineering the optical phase noise, we manipulate the visibil- ity of interference fringes in a Mach-Zehnder interferometer that incorporates two acousto-optic modulators. Such controlled dephasing finds applications in modern experiments involving the spread or diffusion of light in an optical network. Further, we analytically show how engineered partial phase noise can convert the dark port of a stabilised interferometer to a weak source of highly correlated photons.

  13. Acousto-optical properties of metamaterials

    Pustovoit, V. I.

    2016-02-01

    The possibility of the effective use of metamaterials in acousto-optics is demonstrated. It is shown that photoelastic constants that determine a change in the dielectric constant of a heterogeneous medium under the action of a sound wave can significantly exceed the corresponding constants for conventional crystals. We have analysed the mechanisms of the dielectric constant variation in a heterogeneous medium consisting of nanoparticles in the form of ellipsoids and have found explicitly the values of the photoelastic constants. It is shown that the mechanism of the dielectric constant variation in a longitudinal sound wave is reduced to a change in the local concentration of nanoparticles in the bulk and in a transverse acoustic wave - to a local rotation of space-oriented nanoellipsoids. It is also shown that the use of metamedia with a nonuniform distribution of nanoparticles provides a unique opportunity for designing qualitatively new instruments and devices that cannot be produced on the basis of conventional crystals. It is noted that metamaterials open ample opportunities for creating devices of the IR region of the spectrum due to the absence of restrictions on the size of such media.

  14. Quantum acousto-optic transducer for superconducting qubits

    Shumeiko, V S

    2015-01-01

    We propose theory for reversible quantum transducer connecting superconducting qubits and optical photons using acoustic waves in piezoelectrics. The proposed device consists of integrated acousto-optic resonator that utilizes stimulated Brillouin scattering for phonon-photon conversion, and piezoelectric e?ect for coupling of phonons to qubits. We evaluate the phonon-photon coupling rate, and show that the required power of optical pump as well as the other device parameters providing full and faithful quantum conversion are feasible for implementation with the state of the art integrated acousto-optics.

  15. The quantum acousto-optic effect in Bose-Einstein condensate

    Bhattacherjee, Aranya B.

    2009-09-01

    We investigate the interaction between a single mode light field and an elongated cigar shaped Bose-Einstein condensate (BEC), subject to a temporal modulation of the trap frequency in the tight confinement direction. Under appropriate conditions, the longitudinal sound like waves (Faraday waves) in the direction of weak confinement acts as a dynamic diffraction grating for the incident light field analogous to the acousto-optic effect in classical optics. The change in the refractive index due to the periodic modulation of the BEC density is responsible for the acousto-optic effect. The dynamics is characterised by Bragg scattering of light from the matter wave Faraday grating and simultaneous Bragg scattering of the condensate atoms from the optical grating formed due to the interference between the incident light and the diffracted light fields. Varying the intensity of the incident laser beam we observe the transition from the acousto-optic effect regime to the atomic Bragg scattering regime, where Rabi oscillations between two momentum levels of the atoms are observed. We show that the acousto-optic effect is reduced as the atomic interaction is increased.

  16. Sound field reconstruction based on the acousto-optic effect

    Torras Rosell, Antoni; Barrera Figueroa, Salvador; Jacobsen, Finn

    2011-01-01

    , namely the acousto-optic effect. When sound propagates through a medium, it gives rise to pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the speed of light is not constant, but changed by the acoustic field. This acousto-optic interaction can be...... measured with a laser Doppler vibrometer; furthermore, it can be exploited to characterize an arbitrary sound field using tomographic techniques. This paper briefly reviews the fundamental principles governing the acousto-optic effect in air, and presents an investigation of the tomographic reconstruction......Acoustic measurements are usually carried out with transducers that interact mechanically with the sound field under investigation. The goal of this work is to employ a completely different measurement principle, the determination of sound pressure based on the interaction between sound and light...

  17. Acousto-optically induced unidirectional and single frequency operation of a Nd:glass ring laser using the acousto-optic effect in the laser medium

    Clarkson, W.A.; Hanna, D.C.; Lovering, D.S.; Jones, G.C.W.

    1994-01-01

    A traveling-wave acousto-optic modulator fabricated from Nd-doped phosphate glass is used both as the laser gain medium and as the unidirectional element in a diode-pumped ring laser. Unidirectional operation can be maintained with applied rf powers as low as 6.7 mW and results in cw single-frequency output powers as high as 200 mW for a pump power of 1.2 W

  18. A beamforming system based on the acousto-optic effect

    Torras Rosell, Antoni; Barrera Figueroa, Salvador; Jacobsen, Finn

    Beamforming techniques are usually based on microphone arrays. The present work uses a beam of light as a sensor element, and describes a beamforming system that locates sound sources based on the acousto-optic effect, this is, the interaction between sound and light. The use of light as a sensing...

  19. Acousto-Optics Tunable Filter Based on a Hollow Optical Fiber for Broadband Polarization Switch Application

    Jaewon; Lee; Jaewang; Yu; Sangsoo; Choi; Kyunghwan; Oh; Dong; Il; Yum; Byoung; Yoon; Kim

    2003-01-01

    A novel acousto-optic tunable filter (AOTF) using a hollow optical fiber (HOF) is proposed. Its broadband rejection over 100nm was observed and high polarization dependence as a polarization switch is discussed.

  20. Acousto-optic deflector of depolarized laser radiation

    Antonov, S. N.

    2016-01-01

    An original acousto-optic deflector is based on the anisotropic diffraction in the paratellurite crystal. The deflector is characterized by a relatively high diffraction efficiency for depolarized laser radiation. The deflector consists of two sequential acousto-optic cells. Each cell deflects one of the orthogonally polarized components of the originally depolarized radiation. The first and second cells scan the low- and highfrequency parts of the angular interval, respectively. The simultaneous and independent operation of the cells makes it possible to use the entire optical (laser) power. A frequency band of 32 MHz is almost reached for depolarized radiation with a wavelength of 1.06 µm and the absolute angular interval is 50 mrad at a total efficiency of no less than 70%.

  1. Experimental study of z resolution in acousto-optical coherence tomography using random phase jumps on ultrasound and light

    Lesaffre, Max; Ramaz, François; Gross, Michel; 10.1364/AO.52.000949

    2013-01-01

    Acousto-Optical Coherence Tomography (AOCT) is a variant of Acousto Optic Imaging (also called Ultrasound modulated Optical Tomography) that makes possible to get resolution along the ultrasound propagation axis $z$. We present here new AOCT experimental results, and we study how the $z$ resolution depends on time step between phase jumps $T_\\phi$, or on the correlation length $\\Delta z$. By working at low resolution, we perform a quantitative comparison of the $z$ measurements with the theoretical Point Spread Function (PSF). We present also images recorded with different $z$ resolution, and we qualitatively show how the image quality varies with $T_\\phi$, or $\\Delta z$.

  2. Triple product acousto-optical processor for the astrophysical applications

    Shcherbakov, Alexandre S.; Hanessian de la Garza, Ana Virginia; Chavushyan, Vahram; Campos Acosta, Joaquin

    2012-10-01

    This processor is oriented to studies in the extra-galactic astronomy as well as to searching the extra-solar planets, so that algorithm of the space-and-time integrating is desirable for a wideband spectrum analysis with an improved resolution. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z - transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of designing the triple product acousto-optical processor in frames of the astrophysical instrumentation is presented.

  3. ACOUSTO-OPTIC IMAGING IN DIFFERENT FIELDS OF ACOUSTICS

    Mayer, W.

    1990-01-01

    A very short introduction of the principles of light diffraction by ultrasonic waves is followed by a discussion of acousto-optic imaging (schlieren) techniques. This method is often useful to obtain qualitative results of various acoustic phenomena in ultrasonics, underwater sound, material characterization, transducer performance and other areas of acoustics. Examples from different fields of acoustics and some scale model studies will be given, illustrating under what conditions this metho...

  4. Acousto-optic processor for distributed interactive video system

    Volner, Rudolf; Ticha, Dasa

    1999-12-01

    This article describes information network - a backbone network structure, a video switch topology and acousto- optics processor applications - AOP. Cable is a natural network for carrying high-capacity, bandwidth - in tensity information. In the age of analog program signals, cable capacity was a natural transmission media for broadcasting of color TV and high-fidelity stereo sound programs. In the new digital program signal age, cable high capacity is a natural network for carrying interactive computer-based, data-multimedia programs.

  5. Holographic video display based on guided-wave acousto-optic devices

    Smalley, Daniel E.; Smithwick, Quinn Y. J.; Bove, V. Michael, Jr.

    2007-02-01

    We introduce a new holo-video display architecture ("Mark III") developed at the MIT Media Laboratory. The goal of the Mark III project is to reduce the cost and size of a holo-video display, making it into an inexpensive peripheral to a standard desktop PC or game machine which can be driven by standard graphics chips. Our new system is based on lithium niobate guided-wave acousto-optic devices, which give twenty or more times the bandwidth of the tellurium dioxide bulk-wave acousto-optic modulators of our previous displays. The novel display architecture is particularly designed to eliminate the high-speed horizontal scanning mechanism that has traditionally limited the scalability of Scophony- style video displays. We describe the system architecture and the guided-wave device, explain how it is driven by a graphics chip, and present some early results.

  6. Electro-optic and acousto-optic laser beam scanners

    Heberle, Johannes; Bechtold, Peter; Strauß, Johannes; Schmidt, Michael

    2016-03-01

    Electro-optical deflectors (EOD) and acousto-optical deflectors (AOD) are based on deflection of laser light within a solid state medium. As they do not contain any moving parts, they yield advantages compared to mechanical scanners which are conventionally used for laser beam deflection. Even for arbitrary scan paths high feed rates can be achieved. In this work the principles of operation and characteristic properties of EOD and AOD are presented. Additionally, a comparison to mirror based mechanical deflectors regarding deflection angles, speed and accuracy is made in terms of resolvable spots and the rate of resolvable spots. Especially, the latter one is up to one order of magnitude higher for EOD and AOD systems compared to conventional systems. Further characteristic properties such as response time, damage threshold, efficiency and beam distortions are discussed. Solid state laser beam deflectors are usually characterized by small deflection angles but high angular deflection velocities. As mechanical deflectors exhibit opposite properties an arrangement of a mechanical scanner combined with a solid state deflector provides a solution with the benefits of both systems. As ultrashort pulsed lasers with average power above 100 W and repetition rates in the MHz range have been available for several years this approach can be applied to fully exploit their capabilities. Thereby, pulse overlap can be reduced and by this means heat affected zones are prevented to provide proper processing results.

  7. Ultrasonic power measurement system based on acousto-optic interaction

    He, Liping; Zhu, Fulong; Chen, Yanming; Duan, Ke; Lin, Xinxin; Pan, Yongjun; Tao, Jiaquan

    2016-05-01

    Ultrasonic waves are widely used, with applications including the medical, military, and chemical fields. However, there are currently no effective methods for ultrasonic power measurement. Previously, ultrasonic power measurement has been reliant on mechanical methods such as hydrophones and radiation force balances. This paper deals with ultrasonic power measurement based on an unconventional method: acousto-optic interaction. Compared with mechanical methods, the optical method has a greater ability to resist interference and also has reduced environmental requirements. Therefore, this paper begins with an experimental determination of the acoustic power in water contained in a glass tank using a set of optical devices. Because the light intensity of the diffraction image generated by acousto-optic interaction contains the required ultrasonic power information, specific software was written to extract the light intensity information from the image through a combination of filtering, binarization, contour extraction, and other image processing operations. The power value can then be obtained rapidly by processing the diffraction image using a computer. The results of this work show that the optical method offers advantages that include accuracy, speed, and a noncontact measurement method.

  8. Simulation of acousto-optical interaction in a Mach-Zehnder interferometer

    Dühring, Maria Bayard; Sigmund, Ole; Jensen, Jakob Søndergaard

    [3] it is explained how a SAW can be employed to modulate the output light of a GaAs Mach-Zehnder interferometer (MZI) and experimental results with a relative modulation depth of 40 % are presented. To modulate the light using a MZI a SAW is transmitted perpendicularly to the two waveguide arms and...... acoustic waves”, Rep. Prog. Phys., 68 1639-1701. [2] K.-Y. Hashimoto, “Surface acoustic wave devices in telecommunications modeling and simulation”, Springer, Berlin, 2000, ISBN 3-540-67232-X. [3] M. M. de Lima Jr., M. Beck, R. Hey and P. V. Santos, “Compact Mach-Zehnder acousto-optic modulator”, Applied......The acousto-optical modulation of light in a Mach-Zehnder interferometer affected by a surface acoustic wave, is simulated by the finite element method. It is discussed how the modulation can be improved based on a parameter study of the geometry. Summary A new way to control and modulate light in...

  9. Sound field reconstruction using acousto-optic tomography

    Torras Rosell, Antoni; Barrera Figueroa, Salvador; Jacobsen, Finn

    2012-01-01

    When sound propagates through a medium, it results in pressure fluctuations that change the instantaneous density of the medium. Under such circumstances, the refractive index that characterizes the propagation of light is not constant, but influenced by the acoustic field. This kind of interaction...... governing the acousto-optic effect in air, and demonstrates that it can be measured with a laser Doppler vibrometer in the audible frequency range. The tomographic reconstruction is tested by means of computer simulations and measurements. The main features observed in the simulations are also recognized in...

  10. Transformation of phase dislocations under acousto-optic interaction of optical and acoustical Bessel beams

    Belyi, V. N.; Khilo, P. A.; Kazak, N. S.; Khilo, N. A.

    2016-07-01

    The generation of wavefront phase dislocations of vortex Bessel light beams under acousto-optic (AO) diffraction in uniaxial crystals has been investigated. For the first time the process of AO interaction is studied with participation of Bessel acoustic beams instead of plane waves. A mathematical description of AO interaction is provided, which supposes the satisfaction of two types of phase-matching condition. The acousto-optic processes of transferring optical singularities onto the wavefront of BLBs are investigated and the generation of high-order optical vortices is considered at the interaction of optical and acoustical Bessel beams. The change of Bessel function order or phase dislocation order is explained as a result of the spin–orbital interaction under acousto-optic diffraction of vortex Bessel beams.

  11. Acousto-Optical/Electronic Processor For SAR

    Bicknell, T. J.; Farr, W. H.

    1992-01-01

    Lightweight, compact, low-power apparatus processes synthetic-aperture-radar (SAR) returns in real time, providing imagery aboard moving aircraft or spacecraft platform. Processor includes optical and electronic subsystems that, together, resolve range and azimuth coordinates of radar targets by combination of spatial and temporal integrations.

  12. Reconstruction of a piecewise smooth absorption coefficient by an acousto-optic process

    Ammari, Habib; Garnier, Josselin; Nguyen, Loc Hoang; Seppecher, Laurent

    2012-01-01

    The aim of this paper is to tackle the nonlinear optical reconstruction problem. Given a set of acousto-optic measurements, we develop a mathematical framework for the reconstruction problem in the case where the optical absorption distribution is supposed to be a perturbation of a piecewise constant function. Analyzing the acousto-optic measurements, we establish a new equation in the sense of distributions for the optical absorption coefficient. For doing so, we introduce a weak Helmholtz d...

  13. Space Qualification Issues in Acousto-optic and Electro-optic Devices

    Prasad, Narasimha S.; Taylor, Edward W.; Trivedi, Sudhir; Kutcher, Sue; Soos, Jolanta

    2007-01-01

    Satellite and space-based applications of photonic devices and systems require operational reliability in the harsh environment of space for extended periods of time. This in turn requires every component of the systems and their packaging to meet space qualifications. Acousto- and electro-optical devices form the major components of many current space based optical systems, which is the focus of this paper. The major space qualification issues are related to: mechanical stability, thermal effects and operation of the devices in the naturally occurring space radiation environment. This paper will discuss acousto- and electro-optic materials and devices with respect to their stability against mechanical vibrations, thermal cycling in operating and non-operating conditions and device responses to space ionizing and displacement radiation effects. Selection of suitable materials and packaging to meet space qualification criteria will also be discussed. Finally, a general roadmap for production and testing of acousto- and electro-optic devices will be discussed.

  14. High Performance Acousto-Optic Arrays based on Fiber Bragg Gratings for Measuring Launch Acoustics Project

    National Aeronautics and Space Administration — Intelligent Fiber Optic Systems Corporation (IFOS) proposes to prove the feasibility of innovations in acousto-optic sensor development for measurement of launch...

  15. Collinear Acousto-Optical Transformation of Bessel Light Beams in Biaxial Gyrotropic Crystals

    Belyi, V. N.; Kulak, G. V.; Krokh, G. V.; Shakin, O. V.

    2016-05-01

    The collinear acousto-optical transformation of Bessel light beams in biaxial gyrotropic crystals into two annular, internal conical refraction beams with orthogonal elliptical polarization is studied. It is found that the diffraction efficiency is maximal (~50-60%) for low ultrasound intensities and varies slightly with further increases in acoustic power. At high ultrasound intensities, the intensities of the transmitted and diffracted annular beams differ insignificantly. The possible use of this acousto-optical interaction for creating collinear tuneable narrow-band acousto-optical filters at low ultrasonic frequencies is demonstrated.

  16. Spectral characteristics of single-mode-fiber-based cascaded acousto-optic filters

    In this paper, two cascaded single-mode-fiber-based acousto-optic fiber grating schemes have been proposed and a comparative study on their spectral characteristics has been performed. By serially employing two acoustic transducers with the same geometrical and physical settings, a cascaded configuration of acousto-optic fiber gratings has been established. Experimental results indicate that the mode coupling efficiency has been improved due to the presence of the acoustic transducers in a serial configuration. Moreover, another cascaded acousto-optic tunable filter scheme is implemented based on a reflection configuration, in which an acousto-optic tunable filter is employed with a thin silver film coated at the fiber end as an efficient reflector for both of the core and cladding modes. And, moreover, spectral fringes resulting from the intermodal interference between the fundamental core mode and cladding modes have been experimentally observed, which is basically in accordance with our theoretical simulation result. Further theoretical investigation of its transmission spectral response to the acousto-optical coupling coefficient reveals the possibility to control the interference spectrum through adjusting the acousto-optic coupling strength of a single acoustic fiber grating, which is an important feature for the acoustic-grating-based fiber interferometers to be used in practical applications. (paper)

  17. Use of Multiband Acousto-optic Filters for Spectrally Encoded Signals Generation in Incoherent Optical Communication Systems

    Byshevski-Konopko, O. A.; Proklov, V. V.; Filatov, A. L.; Lugovskoi, A. V.; Korablev, E. M.

    New acousto-optical (AO) coder of spectrally optical signals for optical code division multiple access systems (O-CDMA) was proposed and investigated. The coder was developed on a base of multi-frequency acousto-optical filter (MAOF). Control RF signals for MAOF were synthesized taking into account intermodulation distortions and interferences between different carrier frequencies incoming to MAOF. An industrial LED was used under system investigation.

  18. Guided-wave multichannel acousto-optic devices based on collinear wave propagation

    Proklov, Valery V.; Korablev, E. M.

    1992-11-01

    Recently, there appeared in acousto-optics (AO) a tendency to develop the optical information processing technology based on AO spatial light modulators, which are very promising in relation to very fast analog signal processing and algebraic data processing with digital accuracy. The best widely distinguished way to win many other marketing counterparts lies in the performance of AO interactions in guided wave structures with highly developed planar technology. In contrast to numerous developments devoted to guided wave AO devices the collinear ones facilitate multichannel or 2-D-devices to increase their throughput and processing gain. We discuss general backgrounds of the guided wave AO devices, especially in the case of the collinear wave propagations. Some applications similar to the multichannel collinear AO Bragg cell on LiNbO for 2-D-beam scanning, AO spectrum analysis, 2-D- Fourier signal processing, frequency multiplexing/demultiplexing, and digital vector-matrix multiplication are presented.

  19. A Tunable Acousto-Optic Fiber Filter Based on Two Simultaneous Mode Coupling Processes

    MIAO Ren; ZHANG Wei; FENG Xue; ZHAO Jian-Hui; LIU Xiao-Ming

    2009-01-01

    A dynamically tunable fiber filter realizing complex spectra of phase-shifted long period fiber gratings (LPFGs)is proposed and demonstrated experimentally. The principle of the filter is based on two acousto-optic coupling processes occurring simultaneously. The first coupling process acts as a normal LPFG, while the second makes the coupling direction of the first process change continuously, leading to a similar transmission spectrum with the phase-shifted LPFGs, in which the changing of coupling direction is realized by the discrete phase shifts of the index modulation. By adjusting the acoustic drive signals, its transmission spectrum can be dynamically tuned to realize the phase-shifted LPFGs' spectra under different phase shift numbers and locations.

  20. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    Lyakh, A., E-mail: alyakh@pranalytica.com; Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Patel, C. Kumar N., E-mail: patel@pranalytica.com [Pranalytica, Inc., 1101 Colorado Ave., Santa Monica, California 90401 (United States)

    2015-04-06

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ∼8.5 μm to ∼9.8 μm when the AOM frequency was changed from ∼41MHz to ∼49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ∼4.7 cm{sup −1}. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs.

  1. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ∼8.5 μm to ∼9.8 μm when the AOM frequency was changed from ∼41MHz to ∼49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ∼4.7 cm−1. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs

  2. Three-dimensional reconstruction of sound fields based on the acousto-optic effect

    Fernandez Grande, Efren; Torras Rosell, Antoni

    2013-01-01

    -optic tomography via scanning the field with a laser Doppler vibrometer. Consequently, the spatial characteristics of the sound field are captured in the measurement, implicitly bearing the potential for a full holographic reconstruction in a three-dimensional space. Recent studies have examined the reconstruction...... of sound pressure fields from acousto-optic measurements in the audible frequency range, based on Fourier transforms and elementary wave expansion methods. The present study examines the complete reconstruction of the sound field from acousto-optic measurements, recovering all acoustic quantities...

  3. Improving Acousto-Optical Interaction by Mechanical Resonators on a Surface

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    The finite element method is employed to model surface acoustic waves generated by high aspect ratio electrodes and their interaction with an optical wave in a waveguide. With a periodic model it is first shown that these electrodes act as a mechanical resonator, which introduces several confined...... types of surface acoustic waves compared to using a conventional interdigital transducer with thin electrodes. Thus, this indicates a way to improve acousto-optical interaction for integrated modulators.......The finite element method is employed to model surface acoustic waves generated by high aspect ratio electrodes and their interaction with an optical wave in a waveguide. With a periodic model it is first shown that these electrodes act as a mechanical resonator, which introduces several confined......-optical interaction with an optical wave in a waveguide. The difference in effective refractive index is calculated for the case where a positive and a negative electric potential, respectively, are applied to the electrode above the optical waveguide. This difference is increased more than 500 times using these new...

  4. High-Resolution Broadband Millimeter-Wave Astrophysical Spectrometer with Triple Product Acousto-Optical Processor

    Dagostino, Miguel Chavez; Shcherbakov, Alexandre S.; Arellanes, Adan Omar; Chavushyan, Vahram

    An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wide- band spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this al- gorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

  5. Investigating the use of the acousto-optic effect for acoustic holography

    Torras Rosell, Antoni; Fernandez Grande, Efren; Jacobsen, Finn; Barrera Figueroa, Salvador

    2012-01-01

    Recent studies have demonstrated that the acousto-optic effect, that is, the interaction between sound and light, can be used as a means to visualize acoustic fields in the audible frequency range. The changes of density caused by sound waves propagating in air induce phase shifts to a laser beam...... that travels through the acoustic field. This phenomenon can in practice be captured with a laser Doppler vibrometer (LDV), and the pressure distribution of the acoustic field can be reconstructed using tomography. The present work investigates the potential of the acousto-optic effect in acoustic...... holography. Two different holographic methods are examined for this purpose. One method first reconstructs the hologram plane using acousto-optic tomography and then propagates it using conventional near-field acoustic holography (NAH). The other method exploits the so-called Fourier Slice Theorem and bases...

  6. Double tungsten coil atomic absorption spectrometer based on an acousto-optic tunable filter

    An atomic absorption spectrometer based on a quartz acousto-optic tunable filter (AOTF) monochromator operating in the 271–453 nm range, is described. The instrument was tailored to study the formation and evolution of electrothermal atomic cloud induced either by one or two tungsten coils. The spectrometer also includes a fast response programmable photomultiplier module for data acquisition, and a power supply capable of driving two parallel tungsten coils independently. The atomization cell herein described was manufactured in PTFE and presents a new design with reduced size. Synchronization between the instant of power delivering to start the atomization process and the detection was achieved, allowing for monitoring the atomization and thermal events synchronously and in real time. Absorption signals can be sampled at a rate of a few milliseconds, compatible with the fast phenomena that occur with electrothermal metallic atomizers. The instrument performance was preliminarily evaluated by monitoring the absorption of radiation of atomic clouds produced by standard solutions containing chromium or lead. Its quantitative performance was evaluated by using Cr aqueous solutions, resulting in detection limits as low as 0.24 μg L−1, and a relative standard deviation of 3%. - Highlights: • The use of an Acousto-Optic Tunable Filter (AOTF) as monochromator element in WC AAS is presented for the first time. • The system includes the possibility of using one or two parallel coils. • We propose a new atomization cell design, manufactured on PTFE with reduced size. • The temperature of the coils and the atomic clouds of Pb and Cr were observed synchronously with high temporal resolution

  7. Double tungsten coil atomic absorption spectrometer based on an acousto-optic tunable filter

    Jora, M.Z. [Chemistry Institute, State University of Campinas, 13083-970, Campinas, SP (Brazil); Nóbrega, J.A. [Chemistry Department, Federal University of São Carlos, 13565-905, São Carlos, SP (Brazil); Rohwedder, J.J.R. [Chemistry Institute, State University of Campinas, 13083-970, Campinas, SP (Brazil); Pasquini, C., E-mail: manasses.jora@gmail.com [Chemistry Institute, State University of Campinas, 13083-970, Campinas, SP (Brazil)

    2015-01-01

    An atomic absorption spectrometer based on a quartz acousto-optic tunable filter (AOTF) monochromator operating in the 271–453 nm range, is described. The instrument was tailored to study the formation and evolution of electrothermal atomic cloud induced either by one or two tungsten coils. The spectrometer also includes a fast response programmable photomultiplier module for data acquisition, and a power supply capable of driving two parallel tungsten coils independently. The atomization cell herein described was manufactured in PTFE and presents a new design with reduced size. Synchronization between the instant of power delivering to start the atomization process and the detection was achieved, allowing for monitoring the atomization and thermal events synchronously and in real time. Absorption signals can be sampled at a rate of a few milliseconds, compatible with the fast phenomena that occur with electrothermal metallic atomizers. The instrument performance was preliminarily evaluated by monitoring the absorption of radiation of atomic clouds produced by standard solutions containing chromium or lead. Its quantitative performance was evaluated by using Cr aqueous solutions, resulting in detection limits as low as 0.24 μg L{sup −1}, and a relative standard deviation of 3%. - Highlights: • The use of an Acousto-Optic Tunable Filter (AOTF) as monochromator element in WC AAS is presented for the first time. • The system includes the possibility of using one or two parallel coils. • We propose a new atomization cell design, manufactured on PTFE with reduced size. • The temperature of the coils and the atomic clouds of Pb and Cr were observed synchronously with high temporal resolution.

  8. Optical transmission of single crystal tellurium for application in acousto-optic cells

    The optical properties of single crystals of tellurium (Te) are investigated in order to develop acousto-optic (AO) devices operating in the longwave infrared spectral region. The optical transparency of carefully cut and polished plates and large size samples of Te crystals was measured from 4 to 24 µm. The absorption of ordinary and extraordinary polarized optical beams was measured along various directions in the crystal with respect to the optic axis. Using a 10.6 µm CO2 laser the absorption coefficient for the best samples of Te was found to be 0.07 cm−1 for the ordinary and between 0.07 and 4.0 cm−1 for the extraordinary polarized optical beam. Here, we also discuss the possible application of Te crystals in fabricating AO imaging filters

  9. Investigating the use of the acousto-optic effect for acoustic holography

    Torras Rosell, Antoni; Fernandez Grande, Efren; Jacobsen, Finn;

    2012-01-01

    . Two different holographic methods are examined for this purpose. One method first reconstructs the hologram plane using acousto-optic tomography and then propagates it using conventional near-field acoustic holography (NAH). The other method exploits the so-called Fourier Slice Theorem and bases all...

  10. Guided-wave acousto-optics interactions, devices, and applications

    1990-01-01

    The field of integrated- or guided-wave optics has experienced significant and continuous growth since its inception in the late 1960s. There has been a considerable increase in research and development activity in this field worldwide and some significant advances in the realization of working in­ tegrated optic devices and modules have been made in recent years. In fact, there have already been some commercial manufacturing and technical ap­ plications of such devices and modules. The guided-wave-acoustooptics involving Bragg interactions between guided optical waves and surface acoustic waves is one of the areas of in­ tegrated-optics that has reached some degree of scientific and technological maturity. This topical volume is devoted to an in-depth treatment of this emerging branch of science and technology. Presented in this volume are concise treatments on bulk-wave acoustooptics, guided-wave optics, and surface acoustic waves, and detailed studies of guided-wave acoustooptic Bragg diffraction in thr...

  11. Improving surface acousto-optical interaction by high aspect ratio electrodes

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes that are strongly confined to the surface, causing a significant increase in the strain underneath the surface. A finite element method is employed to model the surface acoustic waves generated by a finite length ...

  12. Analysis of the deviation of the diffracted beams caused by acousto-optic tunable filter in multispectral imaging

    Yu Yang; Xuejun Sha; Zhonghua Zhang

    2011-01-01

    The deviation caused by acousto-optic tunable filter (AOTF) diffraction in multispectral imaging is analyzed through derivation calculus of the deviation angle. The rotatory polarization of acousto-optic crystal is taken into account in this analysis. The relationships between the polar angle of the incident and the diffracted beams are acquired by using the momentum-matching condition. During the diffraction of the incident beams, far more deviations are induced.%@@ The deviation caused by acousto-optic tunable filter(AOTF) diffraction in multispectral imaging is analyzed through derivation calculus of the deviation angle.The rotatory polarization of acousto-optic crystal is taken into account in this analysis.The relationships between the polar angle of the incident and the diffracted beams are acquired by using the momentum-matching condition.During the diffraction of the incident beams,far more deviations are induced.

  13. Improving surface acousto-optical interaction by high aspect ratio electrodes

    Dühring, Maria Bayard; Laude, Vincent; Khelif, Abdelkrim

    2009-01-01

    propagating in a waveguide buried in the lithium niobate substrate supporting the electrodes. The interaction can be increased up to 600 times using these new types of surface acoustic waves as compared to using a conventional IDT with thin electrodes. This result could find applications in improved acousto......The acousto-optical interaction of an optical wave confined inside a waveguide and a surface acoustic wave launched by an interdigital transducer (IDT) at the surface of a piezoelectric material is considered. The IDT with high aspect ratio electrodes supports several acoustic modes that are...... strongly confined to the surface, causing a significant increase in the strain underneath the surface. A finite element method is employed to model the surface acoustic waves generated by a finite length IDT with 12 electrode pairs and subsequently to study their interaction with an optical wave...

  14. High repetition rate laser-induced breakdown spectroscopy using acousto-optically gated detection

    Pořízka, Pavel; Klessen, Benjamin; Kaiser, Jozef; Gornushkin, Igor; Panne, Ulrich; Riedel, Jens

    2014-07-01

    This contribution introduces a new type of setup for fast sample analysis using laser-induced breakdown spectroscopy (LIBS). The novel design combines a high repetition rate laser (up to 50 kHz) as excitation source and an acousto-optical modulator (AOM) as a fast switch for temporally gating the detection of the emitted light. The plasma radiation is led through the active medium of the AOM where it is diffracted on the transient ultrasonic Bragg grid. The diffracted radiation is detected by a compact Czerny-Turner spectrometer equipped with a CCD line detector. Utilizing the new combination of high repetition rate lasers and AOM gated detection, rapid measurements with total integration times of only 10 ms resulted in a limit of detection (LOD) of 0.13 wt.% for magnesium in aluminum alloys. This short integration time corresponds to 100 analyses/s. Temporal gating of LIP radiation results in improved LODs and consecutively higher sensitivity of the LIBS setup. Therefore, an AOM could be beneficially utilized to temporally detect plasmas induced by high repetition rate lasers. The AOM in combination with miniaturized Czerny-Turner spectrometers equipped with CCD line detectors and small footprint diode pumped solid state lasers results in temporally gateable compact LIBS setups.

  15. Double tungsten coil atomic absorption spectrometer based on an acousto-optic tunable filter

    Jora, M. Z.; Nóbrega, J. A.; Rohwedder, J. J. R.; Pasquini, C.

    2015-01-01

    An atomic absorption spectrometer based on a quartz acousto-optic tunable filter (AOTF) monochromator operating in the 271-453 nm range, is described. The instrument was tailored to study the formation and evolution of electrothermal atomic cloud induced either by one or two tungsten coils. The spectrometer also includes a fast response programmable photomultiplier module for data acquisition, and a power supply capable of driving two parallel tungsten coils independently. The atomization cell herein described was manufactured in PTFE and presents a new design with reduced size. Synchronization between the instant of power delivering to start the atomization process and the detection was achieved, allowing for monitoring the atomization and thermal events synchronously and in real time. Absorption signals can be sampled at a rate of a few milliseconds, compatible with the fast phenomena that occur with electrothermal metallic atomizers. The instrument performance was preliminarily evaluated by monitoring the absorption of radiation of atomic clouds produced by standard solutions containing chromium or lead. Its quantitative performance was evaluated by using Cr aqueous solutions, resulting in detection limits as low as 0.24 μg L- 1, and a relative standard deviation of 3%.

  16. Determination of refractive index variation of a glass-integrated optical waveguide by the acousto-optic effect

    Ion exchange on a glass substrate is now a well-known technology that enables the realization of optical waveguide devices. In recent years, the hybridization of ion-exchanged glass waveguides has become a promising method for functional integration. In this context, an integrated Mach–Zehnder interferometer (MZI), made by ion exchange on a glass substrate, was used to realize an acousto-optic modulator. Over one arm of the MZI a PZT ceramic driven by a high-voltage signal was glued. The acoustic waves cross the light waveguide and locally modify the refractive index of the glass. The optical intensity observed at the output of the interferometer varies according to the piezoelectric ceramic excitation. This component is used to find the relation between the refractive index change induced and the applied stress. Measurements were made for two linear polarizations: TE and TM. The proposed method was validated on a specific glass substrate and can be directly extended to any kind of glass

  17. Generation of spectral-encoded signals in noncoherent optical communication systems based on acousto-optic multiwavelength filters

    Proklov, V. V.; Byshevski-Konopko, O. A.; Filatov, A. L.

    2015-10-01

    New acousto-optical (AO) methods and devices necessary for the creation of noncoherent optical code division multiple access (O-CDMA) systems are considered. Based on an AO multiwavelength filter, an original device generating spectral-encoded signals for O-CDMA systems with optimum WDM has been created and studied. It is shown that modern AO technology is capable of surmounting difficulties that previously hindered the transition of optical communication systems to CDMA data transmission.

  18. Depth discrimination in acousto-optic cerebral blood flow measurement simulation

    Tsalach, A.; Schiffer, Z.; Ratner, E.; Breskin, I.; Zeitak, R.; Shechter, R.; Balberg, M.

    2016-03-01

    Monitoring cerebral blood flow (CBF) is crucial, as inadequate perfusion, even for relatively short periods of time, may lead to brain damage or even death. Thus, significant research efforts are directed at developing reliable monitoring tools that will enable continuous, bed side, simple and cost-effective monitoring of CBF. All existing non invasive bed side monitoring methods, which are mostly NIRS based, such as Laser Doppler or DCS, tend to underestimate CBF in adults, due to the indefinite effect of extra-cerebral tissues on the obtained signal. If those are to find place in day to day clinical practice, the contribution of extra-cerebral tissues must be eliminated and data from the depth (brain) should be extracted and discriminated. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133Xe SPECT and laser Doppler. We have assembled a comprehensive computerized simulation, modeling this acousto-optic technique in a highly scattering media. Using the combination of light and ultrasound, we show how depth information may be extracted, thus distinguishing between flow patterns taking place at different depths. Our algorithm, based on the analysis of light modulated by ultrasound, is presented and examined in a computerized simulation. Distinct depth discrimination ability is presented, suggesting that using such method one can effectively nullify the extra-cerebral tissues influence on the obtained signals, and specifically extract cerebral flow data.

  19. Optical modulators with 2D layered materials

    Sun, Zhipei; Martinez, Amos; Wang, Feng

    2016-04-01

    Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that 2D layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this Review, we cover the state of the art of optical modulators based on 2D materials, including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as 2D heterostructures, plasmonic structures, and silicon and fibre integrated structures. We also take a look at the future perspectives and discuss the potential of yet relatively unexplored mechanisms, such as magneto-optic and acousto-optic modulation.

  20. Holographic reconstruction of sound fields based on the acousto-optic effect

    Fernandez Grande, Efren; Torras Rosell, Antoni; Jacobsen, Finn

    2013-01-01

    yielding a full characterization of the sound field. In this study, a direct projection of the Radon transform from one plane to another and into the space domain, based on an elementary wave expansion is proposed. The relationship between the Radon and the wavenumber domains is examined, and the......Recent studies have shown that it is possible to measure a sound field using acousto-optic tomography. Theacousto-optic effect, i.e., the interaction between sound and light, can be used to measure an arbitrary soundfield by scanning it with a laser Doppler vibrometer (LDV) over an aperture; This...

  1. Acousto-optic filter for electronic laser tuning

    Harris, S. E.

    1972-01-01

    Electronically tunable lithium niobate filter utilizes acoustic-optic diffraction for tuning laser to desired frequencies. Filter placed inside laser cavity diffracts incident optical signal of one polarization into orthogonal polarization by collinearly propagating acoustic beam to desired wavelength.

  2. Acousto-optic tunable filter for dispersion characterization of time-domain optical coherence tomography systems.

    Chin, Catherine; Toadere, Florin; Feuchter, Thomas; Leick, Lasse; Moselund, Peter; Bradu, Adrian; Podoleanu, Adrian

    2016-07-20

    A broadband supercontinuum light source with an acousto-optic tunable filter (AOTF) are used to characterize dispersion in two time-domain OCT systems, at 850 and 1300 nm. The filter is designed to sweep across two spectral ranges, which are restricted here from 800 to 900 nm and from 1200 to 1500 nm, respectively. Dispersion compensation for 850 nm was achieved with a spectral delay line. Dispersion compensation for 1300 nm was achieved using BK 7 rod glasses in the reference arm. The AOTF allows evaluation of dispersion in under as well as overcompensated systems. The AOTF method is based on wavelength dependence of the optical path difference corresponding to the maximum strength of the interference signal recorded using a mirror as object. Comparison is made between the AOTF method and the more usual method based on measurement of the full width at half-maximum of the autocorrelation peak. This comparison shows that the AOTF method is more accurate in terms of evaluation of the dispersion left uncompensated after each adjustment. The AOTF method additionally provides information on the direction of dispersion compensation. PMID:27463927

  3. Tunable semiconductor laser with an acousto-optic filter in an external fibre cavity

    A tunable semiconductor laser with a laser amplifier based on a double-pass superluminescent diode as an active element and an acousto-optic filter in an external fibre cavity as a selective element is investigated. A continuous spectral tuning is achieved in a band of width 60 nm centered at a wavelength of 845 nm and the 'instant' linewidth below 0.05 nm is obtained. The sweep frequency within the tuning range achieves 200 Hz. The cw power at the output of a single-mode fibre was automatically maintained constant at the level up to 1.5 mW. (lasers and amplifiers)

  4. Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

    Peled, Itay; Kaminsky, Ron; Kotler, Zvi

    2015-06-01

    In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%. PMID:26192666

  5. Contrast enhancement in microscopy of human thyroid tumors by means of acousto-optic adaptive spatial filtering

    Yushkov, Konstantin B.; Molchanov, Vladimir Y.; Belousov, Pavel V.; Abrosimov, Aleksander Y.

    2016-01-01

    We report a method for edge enhancement in the images of transparent samples using analog image processing in coherent light. The experimental technique is based on adaptive spatial filtering with an acousto-optic tunable filter in a telecentric optical system. We demonstrate processing of microscopic images of unstained and stained histological sections of human thyroid tumor with improved contrast.

  6. An optical modulator

    Thévenaz, Luc; Dainesi, Paolo

    2003-01-01

    An optical modulator is arranged to compensate for the thermo-optical modulating effects induced by charge-injection based phase modulators. It comprises first modulator means (3), that receive optical radiation (11, 21), direct it along an optical path, apply a first predetermined optical phase modulation by the injection of free charges into the optical path, and output optical radiation (13, 22) so modulated. Compensator means (4) apply, to optical radiation output from (13, 22), or to be ...

  7. The Experimental Study on Wide-band Tunable All-fiber Acousto-optic Filter Based on Null Coupler

    LI Tong; LI Qun; LIU Dan; LIU Xiaoming; PENG Jiangde

    2000-01-01

    The fiber acousto-optic filter is fabricated successfully for the first time in China. The mode conversion is realized by the acoustic-wave induced perturbation. Excess loss of 0.1 dB and continuous tuning range between 1470 nm and 1580 nm are obtained. The polarization dependence of the filter is studied experimentally.

  8. Acousto-optically induced single-frequency operation of a monolithic Nd:phosphate glass ring laser

    C. Bollig; Clarkson, W.A.; Hanna, D.C.; Lovering, D.S.; Jones, G.C.W.

    1995-01-01

    A diode-pumped single-frequency monolithic Nd:phosphate glass ring laser is described, in which the acousto-optic effect is used to enforce unidirectional lasing. Output powers up to 30mW for 400mW of pump have been achieved.

  9. Acousto-optic interaction in biconical tapered fibers: shaping of the stopbands

    Ramírez-Meléndez, Gustavo; Bello-Jiménez, Miguel Ángel; Cuadrado-Laborde, Christian; Díez, Antonio; Cruz, José Luis; Rodríguez-Cobos, Amparo; Balderas-Navarro, Raúl; Andrés Bou, Miguel Vicente

    2016-03-01

    The effect of a gradual reduction of the fiber diameter on the acousto-optic (AO) interaction is reported. The experimental and theoretical study of the intermodal coupling induced by a flexural acoustic wave in a biconical tapered fiber shows that it is possible to shape the transmission spectrum, for example, substantially broadening the bandwidth of the resonant couplings. The geometry of the taper transitions can be regarded as an extra degree of freedom to design the AO devices. Optical bandwidths above 45 nm are reported in a tapered fiber with a gradual reduction of the fiber down to 70 μm diameter. The effect of including long taper transition is also reported in a double-tapered structure. A flat attenuation response is reported with 3-dB stopband bandwidth of 34 nm.

  10. On the possibility of developing incoherent fibre-optic data transmission systems based on signal spectral coding with matched acousto-optical filters

    The scheme is suggested for developing the optical communication line based on the principle of code division of multiple access with matched acousto-optical filters and a 16-bit long Walsh sequence. Results of modelling show that such a line can operate if adjacent spectral lines are separated by at least double the Rayleigh criterion. (optical information transmission)

  11. Electro-mechanically induced GHz rate optical frequency modulation in silicon

    Tallur, Siddharth

    2012-01-01

    We present a monolithic silicon acousto-optic frequency modulator (AOFM) operating at 1.09GHz. Direct spectroscopy of the modulated laser power shows asymmetric sidebands which indicate coincident amplitude modulation and frequency modulation. Employing mechanical levers to enhance displacement of the optical resonator resulted in greater than 67X improvement in the opto-mechanical frequency modulation factor over earlier reported numbers for silicon nanobeams.

  12. Tapered acoustical directional couplers for integrated acousto-optical mode converters with weighted coupling

    Herrmann, Harald; Rust, Ulrich; Schafer, Klaus

    1995-03-01

    Weighted coupling for strong sidelobe suppression of integrated acoustooptical mode converters in LiNbO3 using acoustical directional couplers has been studied theoretically and experimentally. A parameter free model for the propagation of surface acoustic waves in guiding structures has been developed based on a step-like variation of the acoustic velocity. Comparisons of theoretical results with experimental ones for acoustic waveguides and directional coupler structures confirm the applicability of the model. A coupled mode description of the acousto-optical polarization conversion in converters with acoustical directional couplers has been developed and applied to several tapered acoustical directional couplers. The model reveals that the conversion characteristics are usually strongly asymmetric. If the directional coupler is appropriately designed, a sidelobe suppression of about 30 dB can be achieved. First experimental results with tapered directional couplers confirm within some limits the theoretical predictions.

  13. Compensation of spatial dispersion of an acousto-optic deflector with a special Keplerian telescope.

    Hu, Qinglei; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

    2016-01-15

    Compensation of spatial dispersion caused by the acousto-optic deflector (AOD) when using a femtosecond laser is difficult across the whole scanning range of the system, and this is a significant impediment to its use. In conventional methods, the dispersion of the AOD was compensated only when it was at a particular position, while at other positions, the quality of the light beam was reduced. We developed a novel method for compensating the spatial dispersion within the entire scanning range using a special Keplerian telescope. Our experimental results show that the residual dispersion of the AOD is compensated sufficiently, and the focal spots of the laser reach the diffraction limit within a 40-MHz ultrasound bandwidth. PMID:26766675

  14. Acousto-optic method used to control water pollution by miscible liquids

    Ferria, Kouider; Griani, Lazhar; Laouar, Naamane

    2012-05-01

    An acousto-optic (A.O.) method has been developed for controlling the quality of water mixed by miscible liquids like acetone or ethanol… The liquid mixture is filled in a rectangular glass cell, which is placed orthogonally to the incident collimated beam of light. This cell consists of a piezoelectric transducer for generating ultrasonic waves. The collimated light while passing through this cell undergoes a diffraction phenomenon. The diffracted dots are collected by a converging photographic objective and displayed in its back focal plane. The location of the diffracted dots and their intensity are sensitive to any variation of the interaction medium. This result leads to decide about the quality of the water.

  15. Application of the acousto-optic effect to pressure measurements in ultrasound fields in water using a laser vibrometer

    Buick, James; J. A. Cosgrove; Douissard, P. -A.; Greated, C. A.; Gilabert, B.

    2004-01-01

    A non-intrusive measuring technique, applied to sensing and measuring acoustic waves at ultrasonic frequencies is considered. The method is optically based and so does not interfere with the ultrasound field. The measurement procedure relies on the acousto-optic effect, that is the change in refractive index which occurs with changing pressure in the ultrasound field. This change in refractive index is detected through the change in the path length of a laser beam propagating through the regi...

  16. On the possibility of developing incoherent fibre-optic data transmission systems based on signal spectral coding with matched acousto-optical filters

    Proklov, Valerii V.; Byshevski-Konopko, O. A.; Grigorievski, V. I.

    2013-06-01

    The scheme is suggested for developing the optical communication line based on the principle of code division of multiple access with matched acousto-optical filters and a 16-bit long Walsh sequence. Results of modelling show that such a line can operate if adjacent spectral lines are separated by at least double the Rayleigh criterion.

  17. An acousto-optical method for registration of erythrocytes' agglutination reaction—sera color influence on the resolving power

    Doubrovski, V. A.; Medvedeva, M. F.; Torbin, S. O.

    2016-01-01

    The absorption spectra of agglutinating sera were used to determine blood groups. It was shown experimentally that the sera color significantly affects the resolving power of the acousto-optical method of blood typing. In order to increase the resolving power of the method and produce an invariance of the method for sera color, we suggested introducing a probing light beam individually for different sera. The proposed technique not only improves the resolving power of the method, but also reduces the risk of false interpretation of the experimental results and, hence, error in determining the blood group of the sample. The latter is especially important for the typing of blood samples with weak agglutination of erythrocytes. This study can be used in the development of an instrument for instrumental human blood group typing based on the acousto-optical method.

  18. Optimization of spectral filtering parameters of acousto-optic pure rotational Raman lidar for atmospheric temperature profiling

    Zhu, Jianhua; Wan, Lei; Nie, Guosheng; Guo, Xiaowei

    2003-12-01

    In this paper, as far as we know, it is the first time that a novel acousto-optic pure rotational Raman lidar based on acousto-optic tunable filter (AOTF) is put forward for the application of atmospheric temperature measurements. AOTF is employed in the novel lidar system as narrow band-pass filter and high-speed single-channel wavelength scanner. This new acousto-optic filtering technique can solve the problems of conventional pure rotational Raman lidar, e.g., low temperature detection sensitivity, untunability of filtering parameters, and signal interference between different detection channels. This paper will focus on the PRRS physical model calculation and simulation optimization of system parameters such as the central wavelengths and the bandwidths of filtering operation, and the required sensitivity. The theoretical calculations and optimization of AOTF spectral filtering parameters are conducted to achieve high temperature dependence and sensitivity, high signal intensities, high temperature of filtered spectral passbands, and adequate blocking of elastic Mie and Rayleigh scattering signals. The simulation results can provide suitable proposal and theroetical evaluation before the integration of a practical Raman lidar system.

  19. Configurable-bandwidth imaging spectrometer based on an acousto-optic tunable filter

    Vila-Francés, Joan; Calpe-Maravilla, Javier; Muñoz-Mari, Jordi; Gómez-Chova, Luis; Amorós-López, Julia; Ribes-Gómez, Emilio; Durán-Bosch, Vicente

    2006-07-01

    This article presents a new imaging spectrometer called autonomous tunable filtering system. The instrument acquires sequential images at different spectral wavelengths in the visible and near infrared range of the electromagnetic spectrum. The spectral selection is performed by an acousto-optic tunable filter (AOTF), which is driven by a custom radio-frequency (rf) generator based on a direct digital synthesizer (DDS). The DDS allows a high flexibility in terms of acquisition speed and bandwidth selection. The rf power is dynamically controlled to drive the AOTF with the optimum value for each wavelength. The images are formed through a carefully designed optical layout and acquired with a high performance digital camera. The application software controls the instrument and acquires the raw spectral images from the camera. This software optionally corrects the image for the AOTF nonidealities, such as diffraction efficiency variations, spatial nonuniformity, and chromatic aberration, and generates a single multiband image file. Moreover, the software can calculate the reflectance or transmittance of the acquired images. The instrument has been calibrated to give precise and repetitive measurements and has been validated against a high performance point spectrometer. As a case example, the instrument has been successfully used for the mapping of chlorophyll content of plant leaves from their multispectral reflectance images.

  20. A novel acousto-optic tunable filter for use in hyperspectral imaging systems

    Stedham, C.; Draper, M.; Ward, J.; Wachman, E.; Pannell, C.

    2008-02-01

    The design and performance characteristics of a novel Acousto Optic Tunable Filter (AOTF) are presented. Particular attention has been paid to the reduction of optical side lobes, maximising the light throughput and achieving efficient wideband RF matching of a device for use in hyperspectral imaging systems. Conventional AOTFs are known to yield an optical pass band with side lobes at unacceptable levels of ~-10dB relative to the transmission peak. It is known that shaping the acoustic beam ("apodisation") can suppress the side lobe transmission of the AOTF and improve its imaging capabilities. Results of a novel electrode apodisation pattern are presented, reducing sidelobes to ~-25dB. This produces an AOTF which is capable of being placed in a diffraction limited optical system and introduces negligible amounts of image degradation. The large transducer area (associated with the large optical aperture) and acoustic impedance mismatch between the AO substrate (TeO II) and transducer (LiNbO 3) pose a challenge in achieving wideband RF performance. Acoustic mismatch between substrate and transducer has been addressed by the introduction of a special acoustic matching layer in the bond. The layer reduces dispersion in the transducer impedance easing broadband matching. The transducer has a low (resistance which must be matched to the RF driver (typically 50 ohms). This very low impedance may be swamped by the parasitic impedances of the electrode, bond layers and wire bonds used for electrical connection. Thus, the transducer is split into series-connected sections to increase the "bare" impedance. We present results to show the performance increase that can be obtained this way.

  1. Direct multi-channel optical spectrum analysis of radio-wave signals using collinear wave heterodyning in the single acousto-optical cell

    An attempt is made to improve the accuracy of a multi-channel parallel acousto-optical spectrum analysis through involving an additional nonlinear conversion into data processing. For this purpose we investigate the potential of exploiting a co-directional collinear wave heterodyning within an analysis of ultra-high-frequency radio-wave signals. The wave heterodyning under the proposal is performed via mixing the longitudinal elastic waves of finite amplitudes. It leads to a two-cascade processing in the single-crystalline cell and makes it possible to improve the relative frequency resolution of the acousto-optical spectrum analysis by an order of magnitude at the same frequency range. Both the theoretical findings and the corresponding estimations were used in proof-of-principle experiments directed at creating a new type of acousto-optical cell. The general concept of the proposed method and the basic conclusions are confirmed by experiments with the developed acousto-optic cell made of a lead molybdate crystal

  2. Optical modulators with two-dimensional layered materials

    Sun, Zhipei; Wang, Feng

    2016-01-01

    Light modulation is an essential operation in photonics and optoelectronics. With existing and emerging technologies increasingly demanding compact, efficient, fast and broadband optical modulators, high-performance light modulation solutions are becoming indispensable. The recent realization that two-dimensional layered materials could modulate light with superior performance has prompted intense research and significant advances, paving the way for realistic applications. In this review, we cover the state-of-the-art of optical modulators based on two-dimensional layered materials including graphene, transition metal dichalcogenides and black phosphorus. We discuss recent advances employing hybrid structures, such as two-dimensional heterostructures, plasmonic structures, and silicon/fibre integrated structures. We also take a look at future perspectives and discuss the potential of yet relatively unexplored mechanisms such as magneto-optic and acousto-optic modulation.

  3. Deflection of a monochromatic THz beam by acousto-optic methods

    The possibility of controlled deflection of an electromagnetic THz beam of a free-electron laser by acousto-optic (AO) methods has been demonstrated for the first time. The material of the AO deflector was chosen to be single-crystal germanium, which has a fairly large refractive index (n = 4.0) and a relatively low absorption coefficient for electromagnetic waves. The absorption coefficient α in germanium is 0.75 ± 0.02 cm-1 at a wavelength λ = 140 μm. The diffracted beam intensity is shown to be maximum at an effective AO interaction length l = 1/α. A diffraction efficiency of 0.05% at a travelling acoustic wave power of 1.0 W is experimentally obtained. It is established that a change in the ultrasonic frequency from 25 to 39 MHz leads to variation in the external Bragg angle in the range from 19.5° to 27.5°. At a fixed Bragg angle θB = 22.4° the frequency band of diffraction is 4.2 ± 0.1 MHz and the angular range of laser beam scanning reaches 2.5° ± 0.5°. The results obtained indicate that AO interaction can be used for controlled deflection of electromagnetic THz beams. (terahertz radiation)

  4. Deflection of a monochromatic THz beam by acousto-optic methods

    Voloshinov, V B; Nikitin, P A [Department of Physics, M.V. Lomonosov Moscow State University (Russian Federation); Gerasimov, V V; Choporova, Yu Yu [G.I. Budker Institute of Nuclear Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation); Knyazev, B A [Novosibirsk National Research State University, Novosibirsk (Russian Federation)

    2013-12-31

    The possibility of controlled deflection of an electromagnetic THz beam of a free-electron laser by acousto-optic (AO) methods has been demonstrated for the first time. The material of the AO deflector was chosen to be single-crystal germanium, which has a fairly large refractive index (n = 4.0) and a relatively low absorption coefficient for electromagnetic waves. The absorption coefficient α in germanium is 0.75 ± 0.02 cm{sup -1} at a wavelength λ = 140 μm. The diffracted beam intensity is shown to be maximum at an effective AO interaction length l = 1/α. A diffraction efficiency of 0.05% at a travelling acoustic wave power of 1.0 W is experimentally obtained. It is established that a change in the ultrasonic frequency from 25 to 39 MHz leads to variation in the external Bragg angle in the range from 19.5° to 27.5°. At a fixed Bragg angle θ{sub B} = 22.4° the frequency band of diffraction is 4.2 ± 0.1 MHz and the angular range of laser beam scanning reaches 2.5° ± 0.5°. The results obtained indicate that AO interaction can be used for controlled deflection of electromagnetic THz beams. (terahertz radiation)

  5. An acousto-optic tunable filter enhanced CO{sub 2} lidar atmospheric monitor

    Taylor, L.H.; Suhre, D.R.; Mani, S.S. [and others

    1996-12-31

    The atmospheric monitor conceptual design is based on a pulsed CO{sub 2} laser. The narrow laser lines provide high spectral selectivity in the 9-11 {mu}m region, within the 8-14 {mu}m ``fingerprint`` region where most large molecules have unique spectral absorption signatures. Laser power has been chosen so that topological objects, e.g., trees or buildings, as far as 4 km can be used as backreflectors, but the laser intensity is sufficiently low that the laser beam is eye-safe. Time-of-flight measurements give the distance to the topological reflector. The lidar system is augmented with an acousto-optic tunable filter (AOTF) which measures the thermal emission spectra from 3 to 14 {mu}m with a 3 cm{sup -1} passband. Sensitivity to narrow emission lines is enhanced by derivative spectroscopy in which the passband of the AOTF is dithered via the rf drive. Path-averaged concentrations are determined from the emission intensity and laser- determined range.

  6. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies.

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally, these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we demonstrate microwave frequency surface acoustic wave transducers co-integrated with nanophotonic resonators on piezoelectric aluminum nitride substrates. Acousto-optic modulation of the resonance modes at above 10 GHz with the acoustic wavelength significantly below the optical wavelength is achieved. The phase and modal matching conditions in this scheme are investigated for efficient modulation. The new acousto-optic platform can lead to novel optical devices based on nonlinear Brillouin processes and provides a direct, wideband link between optical and microwave photons for microwave photonics and quantum optomechanics. PMID:25400144

  7. The ANTARES Optical Module

    the ANTARES Collaboration

    2001-01-01

    The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km-squared and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R & D studi...

  8. Optical fibre gratings and their applications as acousto-optic devices

    Liu, W. F

    1998-01-01

    1.1 Background Fibre optics has gained prominence in the fields of optical fibre communication, instrumentation, cable television and optical data networks. The major application however is in the area of the optical network where the availability of a wide variety of all-optical components is essential to the development of an all-optical network. Components based on optical fibres are extremely attractive due to their intrinsically low loss and compatibility with the fibre system. R...

  9. Optical modulator including grapene

    Liu, Ming; Yin, Xiaobo; Zhang, Xiang

    2016-06-07

    The present invention provides for a one or more layer graphene optical modulator. In a first exemplary embodiment the optical modulator includes an optical waveguide, a nanoscale oxide spacer adjacent to a working region of the waveguide, and a monolayer graphene sheet adjacent to the spacer. In a second exemplary embodiment, the optical modulator includes at least one pair of active media, where the pair includes an oxide spacer, a first monolayer graphene sheet adjacent to a first side of the spacer, and a second monolayer graphene sheet adjacent to a second side of the spacer, and at least one optical waveguide adjacent to the pair.

  10. Kilohertz generation of high contrast polarization states for visible femtosecond pulses via phase-locked acousto-optic pulse shapers

    We present a detailed analysis of a setup capable of arbitrary amplitude, phase, and polarization shaping of broadband visible femtosecond pulses at 1 kHz via a pair of actively phase stabilized acousto-optic programmable dispersive filters arranged in a Mach-Zehnder interferometer geometry. The setup features phase stability values around λ/225 at 580 nm as well as degrees of polarization of at least 0.9 for any polarization state. Both numbers are important metrics to evaluate a setup's potential for applications based on polarization-shaped femtosecond pulses, such as fully coherent multi-dimensional electronic spectroscopy

  11. Multistage spectral polarimeter based on integrated acousto-optical Ti:LiNbO3 TE-TM converters for WDM system monitoring

    Noe, Reinhold; Maucher, A.; Ricken, Raimund

    1999-04-01

    A 4-stage spectral polarimeter based on Ti:LiNbO3 acousto- optical TE-TM converters has been realized. It has about 20 dB stopband suppression and can measure polarimetric spectra as well as the time evolution of the state of polarization. A simple optical spectrum analyzer is also proposed.

  12. Integrated acousto-optic polarization converter in a ZX-cut LiNbO(3) waveguide superlattice.

    Yudistira, D; Janner, D; Benchabane, S; Pruneri, V

    2009-10-15

    We report an integrated acousto-optic polarization converter exploiting a novel surface acoustic superlattice (S-ASL) transducer. The S-ASL transducer is made of a ZX-cut periodically poled lithium niobate (PPLN) crystal with uniform coplanar electrodes for surface acoustic wave (SAW) generation. For a PPLN period of 20 microm the SAW is excited at an rf of about 190 MHz, while the phase matching occurs at an optical wavelength of around 1456 nm. The measured mode conversion efficiency of 90% at an input rf power of 1 W and the 3 dB optical bandwidth of 2.5 nm confirm the confinement of the SAW between the electrode gap and the constructive interaction along the whole 10 mm electrode length. PMID:19838274

  13. The ANTARES optical module

    The ANTARES collaboration is building a deep sea neutrino telescope in the Mediterranean Sea. This detector will cover a sensitive area of typically 0.1 km2 and will be equipped with about 1000 optical modules. Each of these optical modules consists of a large area photomultiplier and its associated electronics housed in a pressure resistant glass sphere. The design of the ANTARES optical module, which is a key element of the detector, has been finalized following extensive R and D studies and is reviewed here in detail

  14. Femtosecond terahertz time-domain spectroscopy at 36 kHz scan rate using an acousto-optic delay

    Urbanek, B.; Möller, M.; Eisele, M.; Baierl, S.; Kaplan, D.; Lange, C.; Huber, R.

    2016-03-01

    We present a rapid-scan, time-domain terahertz spectrometer employing femtosecond Er:fiber technology and an acousto-optic delay with attosecond precision, enabling scanning of terahertz transients over a 12.4-ps time window at a waveform refresh rate of 36 kHz, and a signal-to-noise ratio of 1.7 × 105 / √{ H z } . Our approach enables real-time monitoring of dynamic THz processes at unprecedented speeds, which we demonstrate through rapid 2D thickness mapping of a spinning teflon disc at a precision of 10 nm/ √{ H z } . The compact, all-optical design ensures alignment-free operation even in harsh environments.

  15. Femtosecond THz time domain spectroscopy at 36 kHz scan rate using an acousto-optic delay

    Urbanek, B; Eisele, M; Baierl, S; Kaplan, D; Lange, C; Huber, R

    2016-01-01

    We present a rapid-scan, time-domain terahertz spectrometer employing femtosecond Er:fiber technology and an acousto-optic delay with attosecond precision, enabling scanning of terahertz transients over a 12.4 ps time window at a waveform refresh rate of 36 kHz, and a signal-to-noise ratio of $1.7 \\times 10^5/\\sqrt{\\rm Hz}$. Our approach enables real-time monitoring of dynamic THz processes at unprecedented speeds, which we demonstrate through rapid 2D thickness mapping of a spinning teflon disc at a precision of $10\\,\\rm nm/\\sqrt{\\rm Hz}$. The compact, all-optical design ensures alignment-free operation even in harsh environments.

  16. Analysis of line broadening and spectral asymmetry in an all-fiber torsional acousto-optic band-pass filter

    The transmission properties of an all-fiber torsional acousto-optic (AO) band-pass filter with a sub-nm bandwidth is studied. The device is based on torsional AO coupling in a highly birefringent (HB) optical fiber. The full width at half maximum (FWHM) measured in a conventional band (C-band) is 0.88 nm, which is compared with the theoretical value of 0.45 nm estimated by using the coupled mode theory. The line broadening and the spectral asymmetry observed in experiments are investigated in detail through our theoretical model and full numerical analyses. The influence of the non-uniformity in the birefringence of the HB fiber on the filter's transmission is analyzed quantitatively in terms of the change in the filtering bandwidth, the sidelobe asymmetry, and the resonance shift.

  17. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF)

    Meng, Zhaokai; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-02-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm-1 to 4500 cm-1, sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies.

  18. Acousto-optical adaptive correction of a chirped laser pulse spectral profile in a Nd-phosphate glass regenerative amplifier

    We present results of experimental research carried out with the help of an acousto-optical light dispersive delay line (LDDL) on spectral correction of chirped laser pulses in a Nd-doped phosphate glass regenerative amplifier (RA) characterized by high gain (G ≈ 4 × 107). The spectral resolution of the LDDL was equal to 1.1 cm−1 at a diffraction efficiency greater than 80%. The use of the LDDL made it possible to implement operating conditions of the RA under which the duration of the output chirped pulse did not shorten in comparison with the duration of the input one, which meant that the width of the spectral emission could be preserved. (letter)

  19. All-fiber tunable laser based on an acousto-optic tunable filter and a tapered fiber.

    Huang, Ligang; Song, Xiaobo; Chang, Pengfa; Peng, Weihua; Zhang, Wending; Gao, Feng; Bo, Fang; Zhang, Guoquan; Xu, Jingjun

    2016-04-01

    An all-fiber tunable laser was fabricated based on an acousto-optic tunable filter and a tapered fiber. The structure was of a high signal-to-noise ratio, therefore, no extra gain flattening was needed in the laser. In the experiment, the wavelength of the laser could be tuned from 1532.1 nm to 1570.4 nm with a 3-dB bandwidth of about 0.2 nm. Given enough nonlinearity in the laser cavity, it could also generate a sliding-frequency pulse train. The laser gains advantages of fast tuning and agility in pulse generation, and its simple structure is low cost for practical applications. PMID:27137035

  20. The effect of input phase modulation to a phase-sensitive optical amplifier

    Li, Tian; Horrom, Travis; Jones, Kevin M; Lett, Paul D

    2016-01-01

    Many optical applications depend on amplitude modulating optical beams using devices such as acousto-optical modulators (AOMs) or optical choppers. Methods to add amplitude modulation (AM) often inadvertently impart phase modulation (PM) onto the light as well. While this PM is of no consequence to many phase-insensitive applications, phase-sensitive processes can be affected. Here we study the effects of input phase and amplitude modulation on the output of a quantum-noise limited phase-sensitive optical amplifier (PSA) realized in hot $^{85}$Rb vapor. We investigate the dependence of PM on AOM alignment and demonstrate a novel approach to quantifying PM by using the PSA as a diagnostic tool. We then use this method to measure the alignment-dependent PM of an optical chopper which arises due to diffraction effects as the chopper blade passes through the optical beam.

  1. Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

    Chamorovskiy, Alexander; Shramenko, Mikhail V.; Lobintsov, Andrei A.; Yakubovich, Sergei D.

    2016-03-01

    We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation, excellent reproducibility and stability of the signal, as well as a high accuracy of wavelength selectivity due to the absence of mechanically moving components. A single AOTF configuration has typical linewidth in 0.05-0.15 nm range due to a frequency shift obtained during each roundtrip. A sequential AOTF arrangement enables instantaneous linewidth generation of power is in the range of 1 mW. While the majority of commercial tunable sources operate in 1060-1550 nm spectral ranges, the 840 nm spectral range is beneficial for optical coherence tomography (OCT). The developed narrow linewidth laser can be relevant for OCT with extended imaging depth, as well as spectroscopy, non-destructive testing and other applications.

  2. Bit error rate optimization of an acousto-optic tracking system for free-space laser communications

    Sofka, J.; Nikulin, V.

    2006-02-01

    Optical communications systems have been gaining momentum with the increasing demand for transmission bandwidth in the last several years. Optical cable based solutions have become an attractive alternative to copper based system in the most bandwidth demanding applications due to increased bandwidth and longer inter-repeater distances. The promise of similar benefits over radio communications systems is driving the research into free space laser communications. Along with increased communications bandwidth, a free space laser communications system offers lower power consumption and the possibility for covert data links due to the concentration of the energy of the laser into a narrow beam. A narrow beam, however, results in a requirement for much more accurate and agile steering, so that a data link can be maintained in a scenario of communication platforms in relative motion or in the presence of vibrations. This paper presents a laser beam tracking system employing an acousto-optic cell capable of deflecting a laser beam at a very high rate (order of tens of kHz). The tracking system is subjected to vibrations to simulate a realistic implementation, resulting in the increase of BER. The performance of the system can be significantly improved through digital control. A constant gain controller is complemented by a Kalman filter the parameters of which are optimized to achieve the lowest possible BER for a given vibrations spectrum.

  3. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

    Wang, Wenbo; Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan

    2016-06-01

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to -0.70 nm within the spectral range of 500-850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.

  4. A modeling-based assessment of acousto-optic sensing for monitoring high-intensity focused ultrasound lesion formation

    Adams, Matthew Tyler

    Real-time acousto-optic (AO) sensing---a dual-wave modality that combines ultrasound with diffuse light to probe the optical properties of turbid media---has been demonstrated to non-invasively detect changes in ex vivo tissue optical properties during high-intensity focused ultrasound (HIFU) exposure. The AO signal indicates the onset of lesion formation and predicts resulting lesion volumes. Although proof-of-concept experiments have been successful, many of the underlying parameters and mechanisms affecting thermally induced optical property changes and the AO detectability of HIFU lesion formation are not well understood. In thesis, a numerical simulation was developed to model the AO sensing process and capture the relevant acoustic, thermal, and optical transport processes. The simulation required data that described how optical properties changed with heating. Experiments were carried out where excised chicken breast was exposed to thermal bath heating and changes in the optical absorption and scattering spectra (500 nm--1100 nm) were measured using a scanning spectrophotometer and an integrating sphere assembly. Results showed that the standard thermal dose model currently used for guiding HIFU treatments needs to be adjusted to describe thermally induced optical property changes. To model the entire AO process, coupled models were used for ultrasound propagation, tissue heating, and diffusive light transport. The angular spectrum method was used to model the acoustic field from the HIFU source. Spatial-temporal temperature elevations induced by the absorption of ultrasound were modeled using a finite-difference time-domain solution to the Pennes bioheat equation. The thermal dose model was then used to determine optical properties based on the temperature history. The diffuse optical field in the tissue was then calculated using a GPU-accelerated Monte Carlo algorithm, which accounted for light-sound interactions and AO signal detection. The simulation was

  5. Narrow linewidth broadband tunable semiconductor laser at 840 nm with dual acousto-optic tunable configuration for OCT applications

    Chamorovskiy, Alexander; Shramenko, Mikhail V.; Lobintsov, Andrei A.; Yakubovich, Sergei D.

    2016-03-01

    We demonstrate a tunable narrow linewidth semiconductor laser for the 840 nm spectral range. The laser has a linear cavity comprised of polarization maintaining (PM) fiber. A broadband semiconductor optical amplifier (SOA) in in-line fiber-coupled configuration acts as a gain element. It is based on InGaAs quantum-well (QW) active layer. SOA allows for tuning bandwidth exceeding 25 nm around 840 nm. Small-signal fiber-to-fiber gain of SOA is around 30 dB. A pair of acousto-optic tunable filters (AOTF) with a quasi-collinear interaction of optical and acoustic waves are utilized as spectrally selective elements. AOTF technology benefits in continuous tuning, broadband operation, excellent reproducibility and stability of the signal, as well as a high accuracy of wavelength selectivity due to the absence of mechanically moving components. A single AOTF configuration has typical linewidth in 0.05-0.15 nm range due to a frequency shift obtained during each roundtrip. A sequential AOTF arrangement enables instantaneous linewidth generation of <0.01 nm by compensating for this shift. Linewidth as narrow as 0.0036 nm is observed at 846 nm wavelength using a scanning Fabry-Perot interferometer with 50 MHz spectral resolution. Output power is in the range of 1 mW. While the majority of commercial tunable sources operate in 1060-1550 nm spectral ranges, the 840 nm spectral range is beneficial for optical coherence tomography (OCT). The developed narrow linewidth laser can be relevant for OCT with extended imaging depth, as well as spectroscopy, non-destructive testing and other applications.

  6. Characterization of the non-collinear acousto-optical cell based on calomel (Hg2Cl2) crystal and operating within the two-phonon light scattering

    Shcherbakov, Alexandre S.; Arellanes, Adan O.

    2016-03-01

    Performances of any system for data processing based on acousto-optical technique are mainly determined by parameters of the acousto-optical cell (AOC) exploited within the schematic arrangement. Here, basic properties of the AOC, involved into a novel processor for precise optical spectrum analysis dedicated to modern astrophysical applications, are considered. Because potential applications of this processor will be focused on investigations in extra-galactic astronomy as well as studies of extra-solar planets, an advanced regime of the non-collinear two-phonon light scattering has been elaborated for spectrum analysis with significantly improved spectral resolution. Under similar uprated requirements, the AOC, based on that specific regime in the calomel (Hg2Cl2) crystal, had been chosen, and its parameters were analyzed theoretically and verified experimentally. Then, the adequate approach to estimating the frequency/spectral bandwidth and spectral resolution had been developed. The bandwidth was calculated and experimentally realized with the additionally involved tilt angle of light incidence, allowing variations for acoustic frequencies. The resolution was characterized taking into account its doubling peculiar to the nonlinear two-phonon mechanism of light scattering. Proof-of-principle experiments were performed with the calomel AOC of 52 mm optical aperture, providing ~94% efficiency in the transmitted light due to the slow-shear acoustic mode of finite amplitude (the acoustic power density ~150 mW/mm2) with the velocity of 0.347×105 cm/s at the radio-wave acoustic frequency ~71 MHz. As a result, we have obtained the spectral resolution <0.235 Å within the spectral bandwidth <290 Å that looks as the best one can mention at the moment in acousto-optics.

  7. Multilevel Modulation formats for Optical Communication

    Jensen, Jesper Bevensee

    2008-01-01

    This thesis studies the use of multilevel modulation formats for optical communication systems. Multilevel modulation is an attractive method of increasing the spectral efficiency of optical communication systems. Various modulation formats employing phase modulation, amplitude modulation or a...

  8. 基于光纤叠栅的全光纤声光可调谐滤波器的特性分析∗%Analysis of all fib er acousto-optic tunable filter based on sup erimp osed fib er Bragg gratings

    2015-01-01

    In this paper, an all fiber acousto-optic tunable filter based on superimposed fiber Bragg gratings (SFBG-AOTF) is demonstrated and studied. Compared to the normal fiber Bragg gratings based all fiber acousto-optic tunable filter, SFBG-AOTF can modulate the two optical resonant wavelengths of the gratings synchronously. The spectrum of SFBG-AOTF at various acoustic frequencies and under acoustically induced strains, has been analyzed theoretically. Based on simulation results, one can find that each order of the secondary reflection peak is symmetrical with respect to the two primary reflection peaks with SFBG as the center, and the resonant wavelength spacing between the primary reflection peak and the secondary reflection peak which is modulated by the former, is proportional to the acoustic frequency. But the resonant wavelength between the same order secondary reflection peaks which are modulated by two different primary reflection peaks, is independent of the acoustic frequency. The acoustically induced strains mainly affect the variation of the reflectivities of the primary and secondary reflection peaks. In the experiment, the spectra of SFBG-AOTF with acoustic frequencies of 390 and 710 kHz, are measured. The variation trend of the experimental results accords well with the simulated one.

  9. Sub-optical wavelength acoustic wave modulation of integrated photonic resonators at microwave frequencies

    Tadesse, Semere Ayalew; Li, Mo

    2014-01-01

    Light-sound interactions have long been exploited in various acousto-optic devices based on bulk crystalline materials. Conventionally these devices operate in megahertz frequency range where the acoustic wavelength is much longer than the optical wavelength and a long interaction length is required to attain significant coupling. With nanoscale transducers, acoustic waves with sub-optical wavelengths can now be excited to induce strong acousto-optic coupling in nanophotonic devices. Here we ...

  10. Optical interconnects for multichip modules

    Haas, Franz; Honey, David A.

    1994-06-01

    A 16-channel plane-to-plane optical interconnect suitable for a multilayer multichip module computer system was demonstrated. a single diffractive optic element was used to focus the outputs from a 4 X 4 array of LEDs son one plane to a corresponding array of photodetectors on a second plane. This architecture can be used to overcome the speed, interconnect number and density, and power limitations of traditional electronic interconnects.

  11. Optical DQPSK Modulation Performance Evaluation

    Costa, Nelson; Cartaxo, Adolfo

    2010-01-01

    The performance evaluation of simulated optical DQPSK modulation has been analysed. The EDP of DQPSK signals is approximately Gaussian-distributed. Thus, a SASM for DQPSK systems performance evaluation based on the GA has been proposed. The SASM relies on the use of the closed-form expressions derived for the mean and STD of the EDP

  12. The visible to the near infrared narrow band acousto-optic tunable filter and the hyperspectral microscopic imaging on biomedicine study

    Based on the parallel tangents momentum-matching condition, a narrow band noncollinear acousto-optic tunable filter (AOTF) using a single TeO2 crystal is designed with the consideration of the birefringence and the rotatory property of the material. An effective setup is established to evaluate the performance of the designed AOTF. The experimental observed spectrum pattern of the diffracted light is nearly the same with the theoretical result. The measured tuning relationship between the diffracted central optical wavelength and acoustic frequency is in accordance with the theoretical prospect. The optical bandwidth of the diffracted light is as narrow as 1.88 nm when the central wavelength is 556.75 nm. The high spectral resolution is significant in practical applications of imaging AOTF. Additionally, the AOTF based hyperspectral microscopic imaging system is established. The stability and the image resolution of the designed narrow band AOTF are satisfying. Finally, the study of the biologic samples indicates the feasibility of our system on biomedicine. (paper)

  13. High Power Continuous-Wave and Acousto-Optic Q-Switched Nd:GdVO4 Laser Operated at 912 nm

    GAO Jing; Yu Xin; CHEN Fei; LI Xu-Dong; ZHANG Zhen; YU Jun-Hua; WANG Yue-Zhu

    2008-01-01

    We present a high power and efficient operation of the 4F3/2→4I9/2transition in Nd:GdVO4 at 912 nm.In the cw mode,the maximum output power of 8.6 W is achieved when the incident pump power is 40.3W,leading to a slope efficiency of 33.3%and an optical-optical efficiency of 21.3%.To the best of our knowledge,this is the highest cw laser power at 912nm obtained with the conventional Nd:GdVO4 crystal.Pulsed operation of 912 nm laser has also been realized by inserting a small acousto-optic (A-O)Q-Switch inside the resonator.As a result,the minimal pulse width of 20ns and the average laser power 1.43 W at the repetition rate of 10kHz are obtained,corresponding to 7.1 kW peak power.We believe that this is the highest laser peak power at 912 nm.Furthermore.duration of 65 ns has also been acquired when the repetition rate is 100 kHz.

  14. Optical Electronics. Electronics Module 9. Instructor's Guide.

    Franken, Bill

    This module is the ninth of 10 modules in the competency-based electronics series. Introductory materials include a listing of competencies addressed in the module, a parts/equipment list, and a cross reference table of instructional materials. Five instructional units cover: fiber optic cable; optical coupler; lasers and masers; optical displays;…

  15. Efficient diode-pumped acousto-optic Q-switched Er:Yb:GdAl(3)(BO(3))(4) pulse laser at 1522  nm.

    Chen, Y J; Lin, Y F; Huang, J H; Gong, X H; Luo, Z D; Huang, Y D

    2015-11-01

    End-pumped by a continuous-wave 976 nm diode laser, efficient 1522 nm laser operation was demonstrated in an Er:Yb:GdAl(3)(BO(3))(4) crystal when a sapphire crystal was used as a heat diffuser. A continuous-wave 1522 nm laser with a maximum output power of 750 mW and slope efficiency of 36% was realized at an absorbed pump power of 4.1 W. The pulse performances of an acousto-optic Q-switched laser with various repetition frequencies were investigated in detail. In a repetition frequency range of 1-10 kHz, 1522 nm pulse lasers with a slope efficiency of about 10%, peak output power at the kilowatt level, and width of about 50 ns were first obtained in an Er:Yb:GdAl(3)(BO(3))(4) crystal pumped by a continuous-wave diode laser. The results indicate that the crystal is a promising gain medium for an actively Q-switched 1.5 μm laser. PMID:26512485

  16. A fundamental mode miniature acousto-optically Q-switched Nd:YVO4 laser with short pulse width at high repetition rates

    A miniature, high repetition rate, short pulse width acousto-optically Q-switched Nd:YVO4 laser in fundamental mode is presented. Miniature solid-state lasers have the characteristics of short cavity length and small mode area in the cross section, which, on the one hand, benefits high gain, high repetition rate and short pulse width, on the other hand, makes it difficult to achieve high mode-matching efficiency and causes higher order modes oscillation. The thermal lens in Nd:YVO4 is treated as thick lens under high pump intensity. The mode-matching efficiency is analyzed with the thermal lens being equivalent to a thin lens array. In high repetition rate Q-switching operation, 3.6 ns pulses at 500 kHz repetition rate with 20 mm cavity length and 4.1 kW peak power are achieved, without active control of pump beam quality. The laser beam quality factors were measured to be Mx2 = 2.03, My2 = 2.46. By improving the pump beam quality and utilizing the optimal pump beam waist radius and location, the mode-matching efficiency and laser beam quality are improved. 4.0 ns pulses at 500 kHz with 2.5 kW peak power are produced. The beam quality factors were measured to be Mx2 = 1.31, My2 = 1.43

  17. Plasma optical modulators for intense lasers

    Yu, Lu-Le; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D A; Mori, W B; Zhang, Jie

    2016-01-01

    Optical modulators can be made nowadays with high modulation speed, broad bandwidth, while being compact, owing to the recent advance in material science and microfabrication technology. However, these optical modulators usually work for low intensity light beams. Here, we present an ultrafast, plasma-based optical modulator, which can directly modulate high power lasers with intensity up to 10^16 W/cm^2 level to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser beams in a sub-mm-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser beam is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are presented. Such optical modulators may enable new applications in the high field physics.

  18. Noise and detection in ''optical'' modulation spectroscopy

    The measuring techniques suitable for ''optical'' modulation spectroscopy are analyzed and source of noise identified. The choice of optical detector is for photoelectrical devices. It is shown that the shot noise of phototubes is the most important noise source

  19. Phase-Modulated Optical Communication Systems

    Ho, Keang-Po

    2005-01-01

    Fiber-optic communication systems have revolutionized our telecommunication infrastructures – currently, almost all telephone land-line, cellular, and internet communications must travel via some form of optical fibers. In these transmission systems, neither the phase nor frequency of the optical signal carries information – only the intensity of the signal is used. To transmit more information in a single optical carrier, the phase of the optical carrier must be explored. As a result, there is renewed interest in phase-modulated optical communications, mainly in direct-detection DPSK signals for long-haul optical communication systems. When optical amplifiers are used to maintain certain signal level among the fiber link, the system is limited by amplifier noises and fiber nonlinearities. Phase-Modulated Optical Communication Systems surveys this newly popular area, covering the following topics: The transmitter and receiver for phase-modulated coherent lightwave systems Method for performance analysis o...

  20. Nanosecond liquid crystalline optical modulator

    Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

    2016-07-26

    An optical modulator includes a liquid crystal cell containing liquid crystal material having liquid crystal molecules oriented along a quiescent director direction in the unbiased state, and a voltage source configured to apply an electric field to the liquid crystal material wherein the direction of the applied electric field does not cause the quiescent director direction to change. An optical source is arranged to transmit light through or reflect light off the liquid crystal cell with the light passing through the liquid crystal material at an angle effective to undergo phase retardation in response to the voltage source applying the electric field. The liquid crystal material may have negative dielectric anisotropy, and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is transverse to the quiescent director direction. Alternatively, the liquid crystal material may have positive dielectric anisotropy and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is parallel with the quiescent director direction.

  1. Plasma optical modulators for intense lasers

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-01-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm−2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations. PMID:27283369

  2. Plasma optical modulators for intense lasers

    Yu, Lu-Le; Zhao, Yao; Qian, Lie-Jia; Chen, Min; Weng, Su-Ming; Sheng, Zheng-Ming; Jaroszynski, D. A.; Mori, W. B.; Zhang, Jie

    2016-06-01

    Optical modulators can have high modulation speed and broad bandwidth, while being compact. However, these optical modulators usually work for low-intensity light beams. Here we present an ultrafast, plasma-based optical modulator, which can directly modulate high-power lasers with intensity up to 1016 W cm-2 to produce an extremely broad spectrum with a fractional bandwidth over 100%, extending to the mid-infrared regime in the low-frequency side. This concept relies on two co-propagating laser pulses in a sub-millimetre-scale underdense plasma, where a drive laser pulse first excites an electron plasma wave in its wake while a following carrier laser pulse is modulated by the plasma wave. The laser and plasma parameters suitable for the modulator to work are based on numerical simulations.

  3. Efficient and high-power green beam generation by frequency doubling of acousto-optic Q-switched diode-side pumped Nd:YAG rod laser in a coupled cavity

    S K Sharma; A J Singh; P K Mukhopadhyay; S M Oak

    2010-11-01

    A 52-W green laser at 532 nm by extra-cavity second-harmonic generation in a coupled-cavity configuration is demonstrated. The fundamental laser is a diode-side-pumped acousto-optic (AO) Q-switched Nd:YAG rod laser producing 84 W of average power at 1064 nm at 8 kHz repetition rate. Type-II phase-matched polished KTP crystal is used as the nonlinear crystal for second-harmonic generation. The individual green pulse width is 50 ns and the fundamental to second harmonic conversion efficiency is 61.8%.

  4. MO-A-BRD-01: An Investigation of the Dynamic Response of a Novel Acousto-Optic Liquid Crystal Detector for Full-Field Transmission Ultrasound Breast Imaging

    Rosenfield, J.R.; La Riviere, P.J. [The University of Chicago, Department of Radiology (United States); Sandhu, J.S. [Santec Systems Inc., Arlington Heights, IL (United States)

    2014-06-15

    Purpose: To characterize the dynamic response of a novel acousto-optic (AO) liquid crystal detector for high-resolution transmission ultrasound breast imaging. Transient and steady-state lesion contrast were investigated to identify optimal transducer settings for our prototype imaging system consistent with the FDA limits of 1 W/cm{sup 2} and 50 J/cm{sup 2} on the incident acoustic intensity and the transmitted acoustic energy flux density. Methods: We have developed a full-field transmission ultrasound breast imaging system that uses monochromatic plane-wave illumination to acquire projection images of the compressed breast. The acoustic intensity transmitted through the breast is converted into a visual image by a proprietary liquid crystal detector operating on the basis of the AO effect. The dynamic response of the AO detector in the absence of an imaged breast was recorded by a CCD camera as a function of the acoustic field intensity and the detector exposure time. Additionally, a stereotactic needle biopsy breast phantom was used to investigate the change in opaque lesion contrast with increasing exposure time for a range of incident acoustic field intensities. Results: Using transducer voltages between 0.3 V and 0.8 V and exposure times of 3 minutes, a unique one-to-one mapping of incident acoustic intensity to steady-state optical brightness in the AO detector was observed. A transfer curve mapping acoustic intensity to steady-state optical brightness shows a high-contrast region analogous to the linear portion of the Hurter-Driffield curves of radiography. Using transducer voltages between 1 V and 1.75 V and exposure times of 90 s, the lesion contrast study demonstrated increasing lesion contrast with increasing breast exposure time and acoustic field intensity. Lesion-to-background contrast on the order of 0.80 was observed. Conclusion: Maximal lesion contrast in our prototype system can be obtained using the highest acoustic field intensity and the

  5. MO-A-BRD-01: An Investigation of the Dynamic Response of a Novel Acousto-Optic Liquid Crystal Detector for Full-Field Transmission Ultrasound Breast Imaging

    Purpose: To characterize the dynamic response of a novel acousto-optic (AO) liquid crystal detector for high-resolution transmission ultrasound breast imaging. Transient and steady-state lesion contrast were investigated to identify optimal transducer settings for our prototype imaging system consistent with the FDA limits of 1 W/cm2 and 50 J/cm2 on the incident acoustic intensity and the transmitted acoustic energy flux density. Methods: We have developed a full-field transmission ultrasound breast imaging system that uses monochromatic plane-wave illumination to acquire projection images of the compressed breast. The acoustic intensity transmitted through the breast is converted into a visual image by a proprietary liquid crystal detector operating on the basis of the AO effect. The dynamic response of the AO detector in the absence of an imaged breast was recorded by a CCD camera as a function of the acoustic field intensity and the detector exposure time. Additionally, a stereotactic needle biopsy breast phantom was used to investigate the change in opaque lesion contrast with increasing exposure time for a range of incident acoustic field intensities. Results: Using transducer voltages between 0.3 V and 0.8 V and exposure times of 3 minutes, a unique one-to-one mapping of incident acoustic intensity to steady-state optical brightness in the AO detector was observed. A transfer curve mapping acoustic intensity to steady-state optical brightness shows a high-contrast region analogous to the linear portion of the Hurter-Driffield curves of radiography. Using transducer voltages between 1 V and 1.75 V and exposure times of 90 s, the lesion contrast study demonstrated increasing lesion contrast with increasing breast exposure time and acoustic field intensity. Lesion-to-background contrast on the order of 0.80 was observed. Conclusion: Maximal lesion contrast in our prototype system can be obtained using the highest acoustic field intensity and the longest breast

  6. Highly Sensitive Electro-Optic Modulators

    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.

  7. Monte Carlo Simulation of Scattered Light with Shear Waves Generated by Acoustic Radiation Force for Acousto-Optic Imaging

    A Monte Carlo method of multiple scattered coherent light with the information of shear wave propagation in scattering media is presented. The established Monte-Carlo algorithm is mainly relative to optical phase variations due to the acoustic-radiation-force shear-wave-induced displacements of light scatterers. Both the distributions and temporal behaviors of optical phase increments in probe locations are obtained. Consequently, shear wave speed is evaluated quantitatively. It is noted that the phase increments exactly track the propagations of shear waves induced by focus-ultrasound radiation force. In addition, attenuations of shear waves are demonstrated in simulation results. By using linear regression processing, the shear wave speed, which is set to 2.1 m/s in simulation, is estimated to be 2.18 m/s and 2.35 m/s at time sampling intervals of 0.2 ms and 0.5 ms, respectively

  8. Acousto-optic Q-switched laser performances of Er3+∶yb3+∶LuAl3(BO3)4 crystal at 1.5-1.6 μm

    Yujin Chen; Yanfu Lin; Haiyong Zhu; Ge Zhang; Yidong Huang

    2012-01-01

    Diode-pumped acousto-optic Q-switched pulse laser at 1.5-1.6μm is obtained in an Er3+:Yb3+:LuAl3 (BO3)4 crystal. Single-pulse laser operation with slope efficiency of 14% and threshold of approximately 100 mW is realized at an average absorbed pump power of 314 mW and repetition frequency of 20 kHz. Output pulse energy is 67 μJ. The effects of pulse repetition frequency, absorbed pump power, and duty cycle on the wavelength and pulse profile of the Q-switched Er3+:Yb3+:LuAl3(BO3)4 laser are also investigated.%Diode-pumped acousto-optic Q-switched pulse laser at 1.5-1.6 μm is obtained in an Er3+∶Yb3+∶LuAl3 (BO3)4 crystal.Single-pulse laser operation with slope efficiency of 14% and threshold of approximately 100 mW is realized at an average absorbed pump power of 314 mW and repetition frequency of 20 kHz.Output pulse energy is 67 μJ.The effects of pulse repetition frequency,absorbed pump power,and duty cycle on the wavelength and pulse profile of the Q-switched Er3+∶yb3+∶LuAl3(BO3)4 laser are also investigated.

  9. Optically Modulated Multiband Terahertz Perfect Absorber

    Seren, Huseyin R.; Keiser, George R.; Cao, Lingyue;

    2014-01-01

    response of resonant metamaterials continues to be a challengingendeavor. Resonant perfect absorbers have flourished as one of the mostpromising metamaterial devices with applications ranging from power har-vesting to terahertz imaging. Here, an optically modulated resonant perfectabsorber is presented...

  10. Acousto-optic effect in a nematic liquid-crystal layer under the binary effect of sound and viscous waves

    The optical effect in a liquid crystal cell containing a homeotropic layer of nematic liquid crystal (NLC) is analyzed. An NLC layer, located between crossed polaroids and opaque in the absence of external effect, is cleared after irradiation by an ultrasonic beam with a sharp spatial boundary. This enlightenment is suggested to be caused by the reorientation of crystal molecules in the acoustic flows that arise under the binary effect of the layer compression in the irradiated region and the viscous waves propagating from the layer boundaries. The flows were calculated taking into account the stress caused by the velocity convection and crystal structure relaxation. An expression is derived for the cell transparency, and the relative role of the convection and relaxation processes in the effect is determined.

  11. Use of acousto-optic grating as a sensor for determining the adulteration in liquids being used in daily life

    Soni, Kirti; Kasana, R. S.

    2008-01-01

    An optical sensor has been developed for finding the proportional composition of two liquids in a mixture. The variation of the refractive index of a liquid produces light diffraction phenomenon. A liquid mixture is filled in a rectangular glass cell, which is placed orthogonically to the incident collimated beams of light. This cell consists of a piezoelectric crystal vibrator for generating ultrasonic waves. The collimated light while passing through this cell gets diffracted. The diffracted dots are collected by a converging lens and displayed in the back focal plane of the lens. The location of the diffracted dots decide the composition of mixture constituents namely fuel oils, edible oils, wine, water, etc. Thus, the adulteration of various liquids can be determined by having the knowledge of the position of diffraction dots.

  12. Acousto-optic effect in a nematic liquid-crystal layer under the binary effect of sound and viscous waves

    Kozhevnikov, E. N., E-mail: kozhev@ssu.samara.ru [Samara State University (Russian Federation)

    2010-03-15

    The optical effect in a liquid crystal cell containing a homeotropic layer of nematic liquid crystal (NLC) is analyzed. An NLC layer, located between crossed polaroids and opaque in the absence of external effect, is cleared after irradiation by an ultrasonic beam with a sharp spatial boundary. This enlightenment is suggested to be caused by the reorientation of crystal molecules in the acoustic flows that arise under the binary effect of the layer compression in the irradiated region and the viscous waves propagating from the layer boundaries. The flows were calculated taking into account the stress caused by the velocity convection and crystal structure relaxation. An expression is derived for the cell transparency, and the relative role of the convection and relaxation processes in the effect is determined.

  13. The optical module of Baikal-GVD

    Avrorin A.D.

    2016-01-01

    Full Text Available The Baikal-GVD neutrino telescope in Lake Baikal is intended for studying astrophysical neutrino fluxes by recording the Cherenkov radiation of the secondary muons and showers generated in neutrino interactions. The first stage of Baikal-GVD will be equipped with about 2300 optical modules. We describe the design of the optical module, the front-end electronics and the laboratory characterization and calibration before deployment.

  14. Optical Response of a Liquid Crystal modulator

    The progress in liquid crystal device technology has led to the development of different electro-optical displays from simple digital watchs to high information content computer screens. In these electro-optical systems modulation of light by means of a liquid crystal device is very important subject both from the point of fundamental physics and for possible technological applications. In this study we describe a liquid crystal modulator which consists of a thin film of liquid crystal contained between parallel conductive glass plates. The surfaces of the plates are treated so that the liquid crystal molecules are parallel to the surfaces but twists about an axis normal to the surfaces by an angle of 90 degree from one substrate to the other. In a liquid crystal modulator the dielectric and optical anisotropies are used to modulate a laser beam passing through the film. If an electric field is applied across the film the molecules realign parallel to the electric field to form the homeotropic structure which has no optical modulation effect. Thus, the electric field-dependent transmission of the liquid crystal modulator is characterized. We also analyze the response behavior of the liquid crystal modulator

  15. Polybinary modulation for bandwidth limited optical links

    Vegas Olmos, Juan José; Jurado-Navas, Antonio

    2015-01-01

    Optical links using traditional modulation formats are reaching a plateau in terms of capacity, mainly due to bandwidth limitations in the devices employed at the transmitter and receivers. Advanced modulation formats, which boost the spectral efficiency, provide a smooth migration path towards...... form of partial response modulation, employs simple codification and filtering at the transmitter to drastically increase the spectral efficiency. At the receiver side, poly binary modulation requires low complexity direct detection and very little digital signal processing. This talk will review the...

  16. Method and apparatus of highly linear optical modulation

    DeRose, Christopher; Watts, Michael R.

    2016-05-03

    In a new optical intensity modulator, a nonlinear change in refractive index is used to balance the nonlinearities in the optical transfer function in a way that leads to highly linear optical intensity modulation.

  17. Graphene Based Optical Phase Modulation

    Midrio, Michele; Romagnoli, Marco; Kimerling, Lionel C; Michel, Jurgen

    2013-01-01

    In this paper we report phase modulation obtained by inducing a capacitive charge on graphene layers embedded in the core of a waveguide. There is a biasing regime in which graphene absorption is negligible but large index variations can be achieved with a voltage-length product as small as $V_\\pi\\,L_\\pi \\simeq 0.04 $\\,V\\,cm . Examples of phase induced changes are computed for straight waveguides and for microring resonators showing the possibility to implement several optoelectronic functionalities as modulators, tunable filters, and switches.

  18. Linear frequency modulation with electronic-optics modulator

    Cao, Changqing; Zeng, Xiaodong; Zheng, Yili; Liu, Huanhuan; Zhao, Xiaoyan

    2007-11-01

    The spatial resolution of a space communication system is constrained by the diffraction limit of the telescope aperture. In a frequency-modulated continuous wave (FMCW), the frequency of the laser is ramped, and the frequency difference between the reflected wave and a local-oscillator wave is monitored. For maximum performance the frequency ramping should be linear. Linear frequency modulation (LFM) of the laser emission is a commonly used method for improving the detection sensitivity. Because of the available technology, techniques that use relatively low modulation frequencies were implemented first. In the early 1980's, an elegant measurement method based on frequency modulation opened up new applications for spectroscopy with spectrally modulated laser light. In this paper we analyzed systematically the principles of saw tooth-wave optical FMCW. For optical FMCW, because all the practical optical waves are from single-mode lasers, and because the laser beam from a single-mode laser is coherent in space due to the nature of stimulated emission, the spatial coherence is always satisfied, and therefore only temporal coherence need be considered. The chip signal, experimental system, and results are analyzed and discussed.

  19. Reconstructions in ultrasound modulated optical tomography

    Allmaras, Moritz

    2011-01-01

    We introduce a mathematical model for ultrasound modulated optical tomography and present a simple reconstruction scheme for recovering the spatially varying optical absorption coefficient from scanning measurements with narrowly focused ultrasound signals. Computational results for this model show that the reconstruction of sharp features of the absorption coefficient is possible. A formal linearization of the model leads to an equation with a Fredholm operator, which explains the stability observed in our numerical experiments. © de Gruyter 2011.

  20. All-Optical Photochromic Spatial Light Modulators

    Beratan, David N.; Perry, Joseph W.

    1989-01-01

    Photochemical transfer of electrons enables fast reading and writing. New concept based on transfer of electrons between donor and acceptor molecules randomly distributed or covalently linked and dispersed in glassy-polymer host material. Transfer causes significant changes in optical-transmission characteristics of material and used to modulate transmission of reading beam of light impinging on material.

  1. Planar Silicon Optical Waveguide Light Modulators

    Leistiko, Otto; Bak, H.

    1994-01-01

    The results of an experimental investigation of a new type of optical waveguide based on planar technology in which the liglht guiding and modulation are achieved by exploiting free carrier effects in silicon are presented. Light is guided between the n+ substrate and two p+ regions, which also...

  2. Electro-optic modulator material

    Adams, John J.; Ebbers, Chris A.

    2005-02-22

    An electro-optic device for use with a laser beam. A crystal has a first face and a second face. Means are provided for applying a voltage across the crystal to obtain a net phase retardation on the polarization of the laser beam when the laser beam is passed through the crystal. In one embodiment the crystal is composed of a compound having the chemical formula ReAe40(BO3)3 where: RE consists of one or more of the following elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and two other elements Y and Sc; and where Ae is from the list of Ca, Sr, or Ba.

  3. Virtual k -Space Modulation Optical Microscopy

    Kuang, Cuifang; Ma, Ye; Zhou, Renjie; Zheng, Guoan; Fang, Yue; Xu, Yingke; Liu, Xu; So, Peter T. C.

    2016-07-01

    We report a novel superresolution microscopy approach for imaging fluorescence samples. The reported approach, termed virtual k -space modulation optical microscopy (VIKMOM), is able to improve the lateral resolution by a factor of 2, reduce the background level, improve the optical sectioning effect and correct for unknown optical aberrations. In the acquisition process of VIKMOM, we used a scanning confocal microscope setup with a 2D detector array to capture sample information at each scanned x -y position. In the recovery process of VIKMOM, we first modulated the captured data by virtual k -space coding and then employed a ptychography-inspired procedure to recover the sample information and correct for unknown optical aberrations. We demonstrated the performance of the reported approach by imaging fluorescent beads, fixed bovine pulmonary artery endothelial (BPAE) cells, and living human astrocytes (HA). As the VIKMOM approach is fully compatible with conventional confocal microscope setups, it may provide a turn-key solution for imaging biological samples with ˜100 nm lateral resolution, in two or three dimensions, with improved optical sectioning capabilities and aberration correcting.

  4. Modeling of a Resonant Tunneling Diode Optical Modulator

    Calado, J. J. N.; Figueiredo, J.M.L.; Ironside, C. N.

    2005-01-01

    The integration of a double barrier resonant tunneling diode within a unipolar optical waveguide provides electrical gain over a wide bandwidth. Due to the non-linearities introduced by the double barrier resonant tunneling diode an unipolar InGaAlAs/InP optical waveguide can be employed both as optical modulator and optical detector. The modeling results of a device operating as optical modulator agree with preliminary experimental data, foreseeing for an optimized device modulation depths u...

  5. Modulation Codes for Optical Data Storage

    Chiueh, Tzi-Dar; Chen, Chi-Yun

    2010-01-01

    In this chapter, modulation codes for optical data storage have been discussed. At first, four types of constraints are introduced, including run-length limited, conservative, low-pass and constant-weight constraints. Since high spatial frequency components tend to be attenuated during recording/reading procedures and long runs of OFF pixels increase difficulty in tracking, the former three types of constraints are proposed to avoid these adverse situations as much as possible. On the other h...

  6. Multiple Isotope Magneto Optical Trap from a single diode laser

    Valenzuela, V M; Gutierrez, M; Gomez, E; 10.1364/JOSAB.30.001205

    2013-01-01

    We present a Dual Isotope Magneto Optical Trap produced using a single diode laser. We generate all the optical frequencies needed for trapping both species using a fiber intensity modulator. All the optical frequencies are amplified simultaneously using a tapered amplifier. The independent control of each frequency is on the RF side rather than on the optical side. This introduces an enormous simplification for laser cooling applications that often require an acousto-optic modulator for each laser beam. Frequency changing capabilities are limited by the modulator bandwidth (10 GHz). Traps for more isotopes can be simply added by including additional RF frequencies to the modulator.

  7. Efficient Electro-Optical Modulation Based on Indium Tin Oxide

    Shi, Kaifeng

    2015-01-01

    We experimentally demonstrate several electro-optical modulators based on transparent conducting oxides. Our previous work demonstrated the modulator structure on glass substrate with broadband bias polarity-dependent modulation. Further exploration shows similar modulation effect of the modulator on quartz and silicon substrate.

  8. Linearized Bragg grating assisted electro-optic modulator.

    Khurgin, Jacob B; Morton, Paul A

    2014-12-15

    We propose a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson (GAMI) modulator can operate as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. PMID:25503037

  9. New modulator for the optical signal in a fiber

    ZHANG Tian-hao; JIA Feng; WANG Shun-li; MAN Jiang wei; NIU Kai; WANG Xu-cheng; YANG Jia

    2006-01-01

    A new modulator for the optical signal in a fiber based on multi-beam interference is designed. In the experiment,the distance of a couple of abutted fibers was modulated through a piezoelectric ceramic pipe driven by 50 Hz AC voltage, so that the amplitude of the transmitted optical signal was modulated. The modulation ratio is about 10% ,S/N ratio is about 60 dB and the bandwidth is about 200 KHz.

  10. Terahertz cross-phase modulation of an optical mode

    Lavrinenko, Andrei; Novitsky, Andrey; Zalkovskij, Maksim; Malureanu, Radu; Jepsen, Peter Uhd

    2013-01-01

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

  11. Performance Research of Modulation for Optical Wireless Communication System

    Yan Gao; Min Wu; Weifeng Du

    2011-01-01

    There are many modulation methods suitable for optical wireless communication. OOK, PPM are adopted widely in optical wireless communication for its high average-power-efficiency. DPPM, DPIM and DH-PIM are three new modulation methods for optical wireless communication, which may be the substitutes of PPM because of their better performance in power efficiency and bandwidth efficiency. In this paper, in combination of the characteristic of the atmospheric optical wireless channel, the bandwid...

  12. Modeling of a Resonant Tunneling Diode Optical Modulator

    Calado, J J N; Ironside, C N

    2005-01-01

    The integration of a double barrier resonant tunneling diode within a unipolar optical waveguide provides electrical gain over a wide bandwidth. Due to the non-linearities introduced by the double barrier resonant tunneling diode an unipolar InGaAlAs/InP optical waveguide can be employed both as optical modulator and optical detector. The modeling results of a device operating as optical modulator agree with preliminary experimental data, foreseeing for an optimized device modulation depths up to 23 dB with chirp parameter between -1 and 0 in the wavelength range analyzed (1520 nm - 1600 nm).

  13. Applications of ``PV Optics`` for solar cell and module design

    Sopori, B.L.; Madjdpour, J.; Chen, W. [National Renewable Energy Lab., Golden, CO (United States)

    1998-09-01

    This paper describes some applications of a new optics software package, PV Optics, developed for the optical design of solar cells and modules. PV Optics is suitable for the analysis and design of both thick and thin solar cells. It also includes a feature for calculation of metallic losses related to contacts and back reflectors.

  14. 160 Gb/s Silicon All-Optical Data Modulator based on Cross Phase Modulation

    Hu, Hao; Pu, Minhao; Ji, Hua; Galili, Michael; Mulvad, Hans Christian Hansen; Yvind, Kresten; Hvam, Jørn Märcher; Jeppesen, Palle; Oxenløwe, Leif Katsuo

    2012-01-01

    We have demonstrated 160 Gb/s all-optical data modulation with an extinction ratio of 18.5 dB based on XPM in a silicon nanowire. Error free performance is achieved for the optically modulated 160 Gb/s signal.......We have demonstrated 160 Gb/s all-optical data modulation with an extinction ratio of 18.5 dB based on XPM in a silicon nanowire. Error free performance is achieved for the optically modulated 160 Gb/s signal....

  15. Modulational instability of short pulses in long optical fibers

    Shukla, P. K.; Juul Rasmussen, Jens

    1986-01-01

    The effect of time-derivative nonlinearity is incorporated into the study of the modulational instability of heat pulses propagating through long optical fibers. Conditions for soliton formation are discussed......The effect of time-derivative nonlinearity is incorporated into the study of the modulational instability of heat pulses propagating through long optical fibers. Conditions for soliton formation are discussed...

  16. All-optical demultiplexing using an electroabsorption modulator

    Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

    2000-01-01

    In the 1990s, the electroabsorption modulator (EAM) has found a wide range of applications. Functionalities such as pulse generation and demultiplexing by electrical modulation have been demonstrated using an EAM. Recently, all-optical wavelength conversion, demultiplexing, and signal regeneration, have also been experimentally demonstrated. In this paper, we investigate all-optical demultiplexing from 80 to 10 Gbit/s.

  17. Module optical analyzer: Identification of defects on the production line

    Herrero Martin, Rebeca; Askins, Stephen; Anton Hernandez, Ignacio; Sala Pano, Gabriel; Araki, Kenji; Nagai, Hirokazu

    2014-01-01

    The usefulness of the module optical analyzer when identifying module defects on production line is presented in this paper. Two different case studies performed with two different kind of CPV modules are presented to show the use of MOA both in IES-UPM and Daido Steel facilities.

  18. Subcarrier intensity modulated free-space optical communication systems

    Popoola, Wasiu Oyewole

    2009-01-01

    This thesis investigates and analyses the performance of terrestrial free-space optical communication (FSO) system based on the phase shift keying pre-modulated subcarrier intensity modulation (SIM). The results are theoretically and experimentally compared with the classical On-Off keying (OOK) modulated FSO system in the presence of atmospheric turbulence. The performance analysis is based on the bit error rate (BER) and outage probability metrics. Optical signal traversing the atmospheric ...

  19. A process to control light in a micro resonator through a coupling modulation by surface acoustic waves

    Fan, Guofang; Li, Yuan; Hu, Chunguang; Lei, Lihua; Guo, Yanchuan

    2016-08-01

    A novel process to control light through the coupling modulation by surface acoustic wave (SAW) is presented in an optical micro resonator. An optical waveguide modulator of a racetrack resonator on silicon-on-insulator (SOI) technology is took as an example to explore the mechanism. A finite-difference time-domain (FDTD) is developed to simulate the acousto-optical (AO) modulator using the mechanism. An analytical method is presented to verify our proposal. The results show that the process can work well as an optical modulator by SAW.

  20. Optical Bistability And Hysteresis In A Solid State Ring Laser

    Kornienko, L. S.; Kravtsov, N. S.; Shelaev, A. N.

    1985-01-01

    The phenomena of optical bistability, hysteresis and memory under the interaction of oppositely directed (OD) light waves in a CW YAG:Nd3+ solid state ring laser (SRL) have been experimentally discovered. The possibilities of spontaneous or forced (with modulated SRL parameters) commutation of the radiation direction without transients at the relaxation frequency (typical for solid state lasers) have been established both in the single-mode and in the mode-locking regimes with various feedback circuits. The mode-locking band was found to be substantially broadened by more than an order of magnitude when OD light waves primarily diffracted on a standing ultrasonic wave were returned into the acousto-optical modulator. With such acousto-optical feedback the mode-locking regime has been obtained using a modulator on a running ultrasonic wave.

  1. Advanced Modulation Techniques for High-Performance Computing Optical Interconnects

    Karinou, Fotini; Borkowski, Robert; Zibar, Darko;

    2013-01-01

    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. In...

  2. Ultrasound-modulated optical tomography for thick tissue imaging

    Wang, Lihong V.; Zhao, Xuemei; Jacques, Steven L.

    1995-12-01

    Continuous-wave ultrasonic modulation of scattered laser light has been used to image objects in tissue-simulating turbid media for the first time. We hypothesize that the ultrasound wave focused into the turbid media modulates the laser light passing through the ultrasonic focal spot. The modulated laser light collected by a photomultiplier tube reflects the local mechanical and optical properties in the focal zone. Buried objects in 5-cm thick tissue phantoms are located with millimeter resolution by scanning and detecting alterations of the ultrasound-modulated optical signal. Ultrasound-modulated optical tomography separates the conflict between signal and resolution in purely optical imaging of tissue and does not rely on ballistic or quasi-ballistic photons but on the abundant diffuse photons. The imaging resolution is determined by the focused ultrasonic wave. This technique has the potential to provide a noninvasive, nonionizing, inexpensive diagnostic tool for diseases such as breast cancer.

  3. Multifunctional graphene optical modulator and photodetector integrated on silicon waveguides

    Youngblood, Nathan; Ma, Rui; Koester, Steven J; Li, Mo

    2014-01-01

    For optical communication, information is converted between optical and electrical signal domains at a high rate. The devices to achieve such a conversion are various types of electro-optical modulators and photodetectors. These two types of optoelectronic devices, equally important, require different materials and consequently it has been challenging to realize both using a single material combination, especially in a way that can be integrated on the ubiquitous silicon platform. Graphene, with its gapless band structure, stands out as a unique optoelectronic material that allows both photodetection and optical modulation. Here, we demonstrate a single graphene-based device that simultaneously provides both efficient optical modulation and photodetection. The graphene device is integrated on a silicon waveguide and is tunable with a gate made from another layer of graphene to achieve near-infrared photodetection responsivity of 57 mA/W and modulation depth of 64%. This novel multifunctional device may lead t...

  4. High-power high-efficiency acousto-optically Q-switched rod Nd:YAG laser with 885 nm diode laser pumping

    Liu, K.; Li, F. Q.; Xu, H. Y.; Wang, Z. C.; Zong, N.; Du, S. F.; Bo, Y.; Peng, Q. J.; Cui, D. F.; Xu, Z. Y.

    2013-01-01

    We have demonstrated a compact Q-switched Nd:YAG laser at 1064 nm with 885 nm diode-laser (LD) direct pumping. At a repetition rate of 100 kHz, an average output power of 53 W with beam quality factor M2 of 1.6 was achieved under the absorbed pump power of 122 W, corresponding to an optical-optical efficiency of 43.5% and a slope efficiency of 57.6%, respectively. The pulse width and the peak power at this output power were 112 ns and 4.74 kW, respectively.

  5. Ultrasound-modulated optical tomography for dense turbid media

    Wang, Lihong V.; Zhao, Xuemei; Jacques, Steven L.

    1996-04-01

    Continuous-wave ultrasonic modulation of scattered laser light has been used to image objects in tissue-simulating turbid media for the first time. We hypothesized that the ultrasound wave focused into the turbid media modulates the laser light passing through the ultrasonic focal zone. The modulated laser light collected by a photomultiplier tube reflects the local mechanical and optical properties in the focal zone. Buried objects in 5-cm thick tissue phantoms (absorption coefficient (mu) $a) equals 0.1 cm-1, reduced scattering coefficient (mu) s' equals 10 cm-1) were located with millimeter resolution by scanning and detecting alterations of the ultrasound-modulated optical signal.

  6. Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

    Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

    2015-04-01

    A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

  7. Fiber optic feedthrough module and method of making same

    A fiber optic feedthrough module which comprises a metal sleeve, a fiber optic element extending through the sleeve in spaced relation thereto, and a tandem series of centrally-apertured mating annular sealant bodies of thermoplastic material surrounding the fiber optic element and compressed between it and the sleeve. The module is made by first providing a loose subassembly of a plurality of individual but interfitting sealant bodies on the fiber optic element and then inserting this subassembly into a metal sleeve, following by swaging the whole assembly which eliminates clearances and provides sealed interfaces between the various contacting components. (author)

  8. Study of an electro-optic modulator capable of generating simultaneous amplitude and phase modulations

    Cusack, B J; Shaddock, D A; Gray, M B; Lam, P K; Whitcomb, S E; Cusack, Benedict J; Gray, Malcolm B; Lam, Ping Koy; Shaddock, Daniel A; Sheard, Benjamin S; Whitcomb, Stan E

    2003-01-01

    We report on the analysis and prototype-characterization of a dual-electrode electro-optic modulator that can generate both amplitude and phase modulations with a selectable relative phase, termed a universally tunable modulator (UTM). All modulation states can be reached by tuning only the electrical inputs, facilitating real-time tuning, and the device is shown to have good suppression and stability properties. A mathematical analysis is presented, including the development of a geometric phase representation for modulation. The experimental characterization of the device shows that relative suppressions of 38 dB, 39 dB and 30 dB for phase, single-sideband and carrier-suppressed modulations, respectively, can be obtained, as well as showing the device is well-behaved when scanning continuously through the parameter space of modulations. Uses for the device are discussed, including the tuning of lock points in optical locking schemes, single sideband applications, modulation fast-switching applications, and ...

  9. Optical signal processing using electro-absorption modulators

    Mørk, Jesper; Romstad, Francis Pascal; Højfeldt, Sune;

    2003-01-01

    Reverse-biased semiconductor waveguides are efficient saturable absorbers and have a number of promising all-optical signal processing applications. Results on ultrafast modulator dynamics as well as demonstrations and investigations of wavelength conversion and regeneration are presented....

  10. Optical modulator based on coupled photonic crystal cavities

    Serafimovich, Pavel G.; Kazanskiy, Nikolay L.

    2016-07-01

    We propose and numerically investigate an optical signal modulator based on two-photonic crystal nanobeam cavities coupled through a waveguide. The suggested modulator shifts the resonant frequency over a scalable range. We design a compact optical modulator based on photonic crystal nanobeams cavities that exhibits high stability to manufacturing. Photonic crystal waveguide tuning in the low-intensity region of the resonant mode is demonstrated. The advantages of the suggested approach over the single-resonator optical modulator approaches include the possibilities to shift the modulator frequency over a scalable range that depends on switching energy level and to effectively electrically tune the device in the low-intensity region of the resonant mode.

  11. A capillary optical fiber modulator derivates from magnetic fluid

    Yang, Xinghua; Liu, Yanxin; Zheng, Yao; Li, Shouzhu; Yuan, Libo; Yuan, Tingting; Tong, Chengguo

    2013-09-01

    A novel in-fiber integrated modulator based on magnetic fluid is proposed. The Fe3O4 magnetic fluid is encapsulated into a specially designed capillary optical fiber with a circular waveguide. Experimental results show that the light at 632.8 nm in the circular waveguide can be modulated by only 2.17×10-2 μL of the magnetic fluid under magnetic field. A wide range of modulation-depth from 44% to 75% can be obtained by adjusting the external magnetic field strength, temperature and the concentration of the magnetic fluid. In addition, the modulator shows good stability and repeatability. This work has great potentials in the integrated optical devices such as tunable in-fiber modulators, optical switches and magnetic sensors.

  12. A study of electro-optical modulators for transfer of detector signals by optical fibers

    Preliminary results of an investigation to minimize the local electronics on the detector by the use of electro-optical intensity modulators are reported. The electrical signal from the detector is converted into an optical signal by a Mach-Zehnder interferometer modulator based on the properties of electro-optical crystals such as LiNbO3. The modulator is driven by the electrical signal from a detector element such as the gas proportional straw tube. The optical signal is brought in from a remote source and exits on an optical fiber to a data collection site. The results of the first tests of optical modulators with respect to their application to particle detectors will be presented. These include the optical power requirement, the linearity, the dynamic range, and the noise characteristics. Finally, the outlook for their application on a large scale is discussed. 8 refs., 7 figs

  13. The optical module of the Baikal deep underwater neutrino telescope

    Bagduev, R. I.

    1999-01-01

    A deep underwater Cherenkov telescope has been operating since 1993 in stages of growing size at 1.1 km depth in Lake Baikal. The key component of the telescope is the Optical Module (OM) which houses the highly sensitive phototube QUASAR-370. We describe design and parameters of the QUASAR-370, the layout of the optical module, the front-end electronics and the calibration procedures, and present selected results from the five-year operation underwater. Also, future developments with respect...

  14. Optical modulation in a resonant tunneling relaxation oscillator

    Figueiredo, J.M.L.; Stanley, C.R.; Boyd, A.R.; Ironside, C. N.; McMeekin, S.G.; Leite, A. M. P.

    1999-01-01

    We report high-speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band edge, small changes of the applied voltage give rise to large, high-speed electroabsorption modulation of the light. We have o...

  15. Optical modulation in a resonant tunneling relaxation oscillator

    Figueiredo, J.M.L.; Stanley, C.R.; Boyd, A.R.; Ironside, C. N.

    2005-01-01

    We report high speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band-edge, small changes of the applied voltage give rise to large, high-speed electro-absorption modulation of the light. We have ...

  16. Quantum Hamiltonian theory of an electro-optical modulator

    Miroshnichenko, G. P.; Gleim, A. V.

    2015-07-01

    A Quantum Hamiltonian formalism is proposed for the description of an electro-optical modulator based on the linear Pockels effect. Optical photons interact with photons of a microwave mode in a combined high- Q cavity made of a LiNbO3 crystal. The microwave photons occupy a coherent state, while optical photons have an arbitrary density matrix. The spectrum of a photodetected modulated signal is analyzed as a function of the frequency of a tunable optical filter. Numerical estimates are obtained, and quantum effects in the spectrum, such as the red shift of the central frequency and sidebands, the possibility of modulation of the optical signal by the microwave field vacuum, and the asymmetry of the intensity of the spectral sidebands, are discussed.

  17. High-speed waveguide electro-optic polarization modulator.

    Alferness, R C; Buhl, L L

    1982-10-01

    By careful electrode design we have achieved a 1.7-GHz modulation bandwidth for a Ti:LiNbO(3) integrated-optic TE ? TM mode-converter modulator. Because of the wavelength selectivity of this modulator, it is an attractive device for simultaneously providing multiplexing and signal encoding in future wavelength-multiplexed single-mode light-wave systems. PMID:19714070

  18. Fiber-optic interferometer using frequency-modulated laser diodes

    Beheim, G.

    1986-01-01

    This paper describes an electrically passive fiber-optic interferometer which uses dual frequency-modulated laser diodes. Experimental results show that this type of interferometer can attain a displacement range of 100 micron with subnanometer resolution. This technique can serve as the basis for a number of high-precision fiber-optic sensors.

  19. A study of electro-optical modulators for transfer of detector signals by optical fibers

    Preliminary results of an investigation to minimize the local electronics on the detector by the use of electro-optical intensity modulators are reported. The electrical signal from the detector is converted into an optical signal by a Mach-Zehnder interferometer modulator based on the properties of electro-optical crystals such as LiNbO3. The modulator is driven by the electrical signal is brought in from a remote souce and exits on an optical fiber to a data collection site. The results of the first tests of optical modulators with respect to their application to particle detectors will be presented. These include the optical power requirement, the linearity, the dynamic range, and the noise characteristics. Finally, the outlook for their application on a large scale is discussed

  20. Composite embedded fiber optic data links in Standard Electronic Modules

    Ehlers, S. L.; Jones, K. J.; Morgan, R. E.; Hixson, Jay

    1990-12-01

    The goal of this project is to fabricate a chassis/circuit card demonstration entirely 'wired' with embedded and interconnected optical fibers. Graphite/epoxy Standard Electronic Module E (SEM-E) configured panels have been successfully fabricated. Fiber-embedded SEM-E configured panels have been subjected to simultaneous signal transmission and vibration testing. Packaging constraints will require tapping composite-embedded optical fibers at right angles to the direction of optical transmission.

  1. Optical modulation in a resonant tunneling relaxation oscillator

    Figueiredo, J M L; Boyd, A R; Ironside, C N

    1999-01-01

    We report high speed optical modulation in a resonant tunneling relaxation oscillator consisting of a resonant tunneling diode (RTD) integrated with a unipolar optical waveguide and incorporated in a package with a coplanar waveguide transmission line. When appropriately biased, the RTD can provide wide-bandwidth electrical gain. For wavelengths near the material band-edge, small changes of the applied voltage give rise to large, high-speed electro-absorption modulation of the light. We have observed optical modulation at frequencies up to 14 GHz, associated with sub harmonic injection locking of the RTD oscillation at the fundamental mode of the coplanar transmission line, as well as generation of 33 ps optical pulses due to relaxation oscillation.

  2. OPTICAL WAVELENGTH CONVERTERS BASED ON CROSS GAIN MODULATION AND CROSS PHASE MODULATION IN SOA

    Vikas Thakur

    2012-06-01

    Full Text Available All optical wavelength conversion is demonstrated at 10 Gbit/s over a wavelength span of 10 nm without any bit loss by the use of Semiconductor Optical Amplifier (SOA in a Mach-Zehnder configuration. These wavelength conversion architectures are implemented by using SOA cross-gain modulation (XGM and cross-phase modulation (XPM techniques. We have compared the results of both techniques on the basics of Bit Error Rate (BER and Quality factor.

  3. Electro-Optical Modulator Bias Control Using Bipolar Pulses

    Farr, William; Kovalik, Joseph

    2007-01-01

    An improved method has been devised for controlling the DC bias applied to an electro-optical crystal that is part of a Mach-Zehnder modulator that generates low-duty-cycle optical pulses for a pulse-position modulation (PPM) optical data-communication system. In such a system, it is desirable to minimize the transmission of light during the intervals between pulses, and for this purpose, it is necessary to maximize the extinction ratio of the modulator (the ratio between the power transmitted during an "on" period and the power transmitted during an "off" period). The present method is related to prior dither error feedback methods, but unlike in those methods, there is no need for an auxiliary modulation subsystem to generate a dithering signal. Instead, as described below, dither is effected through alternation of the polarity of the modulation signal. The upper part of Figure 1 schematically depicts a Mach-Zehnder modulator. The signal applied to the electro-optical crystal consists of a radio-frequency modulating pulse signal, VRF, superimposed on a DC bias Vbias. Maximum extinction occurs during the off (VRF = 0) period if Vbias is set at a value that makes the two optical paths differ by an odd integer multiple of a half wavelength so that the beams traveling along the two paths interfere destructively at the output beam splitter. Assuming that the modulating pulse signal VRF has a rectangular waveform, maximum transmission occurs during the "on" period if the amplitude of VRF is set to a value, V , that shifts the length of the affected optical path by a half wavelength so that now the two beams interfere constructively at the output beam splitter. The modulating pulse signal is AC-coupled from an amplifier to the electro-optical crystal. Sometimes, two successive pulses occur so close in time that the operating point of the amplifier drifts, one result being that there is not enough time for the signal level to return to ground between pulses. Also, the

  4. Ultrasound-modulated optical tomography with intense acoustic bursts

    Zemp, Roger J.; Kim, Chulhong; Wang, Lihong V.

    2007-04-01

    Ultrasound-modulated optical tomography (UOT) detects ultrasonically modulated light to spatially localize multiply scattered photons in turbid media with the ultimate goal of imaging the optical properties in living subjects. A principal challenge of the technique is weak modulated signal strength. We discuss ways to push the limits of signal enhancement with intense acoustic bursts while conforming to optical and ultrasonic safety standards. A CCD-based speckle-contrast detection scheme is used to detect acoustically modulated light by measuring changes in speckle statistics between ultrasound-on and ultrasound-off states. The CCD image capture is synchronized with the ultrasound burst pulse sequence. Transient acoustic radiation force, a consequence of bursts, is seen to produce slight signal enhancement over pure ultrasonic-modulation mechanisms for bursts and CCD exposure times of the order of milliseconds. However, acoustic radiation-force-induced shear waves are launched away from the acoustic sample volume, which degrade UOT spatial resolution. By time gating the CCD camera to capture modulated light before radiation force has an opportunity to accumulate significant tissue displacement, we reduce the effects of shear-wave image degradation, while enabling very high signal-to-noise ratios. Additionally, we maintain high-resolution images representative of optical and not mechanical contrast. Signal-to-noise levels are sufficiently high so as to enable acquisition of 2D images of phantoms with one acoustic burst per pixel.

  5. Diffractive optical interconnected multichip module: Demonstration and design

    Morris, James Edward, Jr.

    2000-07-01

    Growth in the optical telecom and datacom industries is requiting new methods of manufacture in order to increase quantities by an order of magnitude while decreasing cost. An optical manufacturing approach utilizing wafer scale optics and integration of wafer scale electronics has potential of solving some of these manufacturing issues. An optical interconnected multichip module (OIMCM) is designed and manufactured to prove the technology. This OIMCM consists of integrated CMOS photodetectors, flip-chip compatible laser array chips, high efficiency diffractive optics, and flip-chip self- alignment for precision alignment of 1-2μm. A method to design a single diffractive surface to operate over a 25nm range in wavelength, typical of the variation in a laser diode, is presented. Also of importance is operation of optical systems over a temperature range. A novel method to athermalize an optical system with a laser diode is presented which utilizes a refractive surface and diffractive surface.

  6. Thermally tuneable optical modulator adapted for differential signaling

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

  7. Polymeric Optical Code-Division Multiple-Access (CDMA) Encoder and Decoder Modules

    Chen, Ray T.; Xuejun Lu

    2011-01-01

    We propose a low cost polymeric optical waveguides-based optical CDMA encoder and decoder modules. The structures of the optical CDMA encoder and decoder modules are presented. The performance of the optical CDMA encoder and decoder modules is simulated using 10-chip binary phase-shift keying (BPSK) coding schemes. The optical CDMA encoder and decoder modules can effectively transmit and recover optical CDMA data streams. The SNR of the received signal is analyzed and determined to be primari...

  8. Wide and stable optical frequency comb in an intensity-modulated continuous wave pumped optical fiber

    This paper investigates how to obtain a wide and stable optical frequency comb in an intensity-modulated continuous-wave pumped optical fiber by straightforwardly characterizing the signal-to-noise ratio and analyzing the optimal fiber length. The stability of the obtained optical frequency comb is analyzed by a method which is similar to the eye pattern. The prospect for obtaining wider and more stable optical frequency combs is discussed. (paper)

  9. All-optical microwave signal processing based on optical phase modulation

    Zeng, Fei

    This thesis presents a theoretical and experimental study of optical phase modulation and its applications in all-optical microwave signal processing, which include all-optical microwave filtering, all-optical microwave mixing, optical code-division multiple-access (CDMA) coding, and ultrawideband (UWB) signal generation. All-optical microwave signal processing can be considered as the use of opto-electronic devices and systems to process microwave signals in the optical domain, which provides several significant advantages such as low loss, low dispersion, light weight, high time bandwidth products, and immunity to electromagnetic interference. In conventional approaches, the intensity of an optical carrier is modulated by a microwave signal based on direct modulation or external modulation. The intensity-modulated optical signal is then fed to a photonic circuit or system to achieve specific signal processing functionalities. The microwave signal being processed is usually obtained based on direct detection, i.e., an opto-electronic conversion by use of a photodiode. In this thesis, the research efforts are focused on the optical phase modulation and its applications in all-optical microwave signal processing. To avoid using coherent detection which is complicated and costly, simple and effective phase modulation to intensity modulation (PM-IM) conversion schemes are pursued. Based on a theoretical study of optical phase modulation, two approaches to achieving PM-IM conversions are proposed. In the first approach, the use of chromatic dispersion induced by a dispersive device to alter the phase relationships among the sidebands and the optical carrier of a phase-modulated optical signal to realize PM-IM conversion is investigated. In the second approach, instead of using a dispersive device, the PM-IM conversion is realized based on optical frequency discrimination implemented using an optical filter. We show that the proposed PM-IM conversion schemes can be

  10. The optical module for the NESTOR neutrino telescope

    Anassontzis, E G; Bottai, S; Cartacci, A; Fanourakis, G K; Grammatikakis, George A; Ioannou, P; Katsanevas, S; Keusen, U; Koske, P; Kourkoumelis, C; Ledenev, V V; Manousakis-Katsikakis, A; McNutt, J; Monteleoni, B; Moraitis, L; Resvanis, L K; Rucol, V K; Siotis, I; Sotiriou, S A; Tsagli, V; Voulgaris, G; Zhukov, V A

    2002-01-01

    NESTOR is a deep-sea water Cherenkov neutrino detector now under construction for deployment in the Mediterranean off Greece. Its key component is an optical module employing a photomultiplier tube with a 15 in. hemispherical photocathode in a transparent glass pressure housing. Extensive tests have been made on the sensitivity, uniformity, time resolution, noise rates and mechanical properties of the module: several test deployments have been made at sea.

  11. Radiometric modulation measuring device of intensity of optical radiation

    A. P. Yanenko

    2014-04-01

    Full Text Available Introduction. The paper proposed a block diagram of radiometric measuring the intensity of optical radiation from modulation conversion parameter input . To assess the intensity of use periodically comparing the reference signal (shaded and measurement (open photodi-odes. Studies. The proposed radiometric modulation meter provides increased sensitivity and measurement accuracy by reducing the influence of dark current measurement and reference photodiodes and compensation intrinsic noise measuring channel through their periodic anti-phase comparison.

  12. High dynamic extinction ratio and pulse modulation of optical signals

    Petrov, A.; Tronev, A. V.; Lebedev, V.; Il'ichev, I. V.; Velichko, E.; Shamray, A.

    2015-11-01

    The use of a saturable absorber for increasing the extinction ratio at external modulation of optical signals is considered. An erbium doped fiber was used as the saturable absorber in the experiments. A considerable increase in the static extinction ratio (up to 50 dB) was demonstrated. A rather long erbium doped fiber relaxation time (about 10 ms) was a limiting factor in the case of pulse modulation. Ways of overcoming this drawback are discussed.

  13. Silicon Modulators, Switches and Sub-systems for Optical Interconnect

    Li, Qi

    Silicon photonics is emerging as a promising platform for manufacturing and integrating photonic devices for light generation, modulation, switching and detection. The compatibility with existing CMOS microelectronic foundries and high index contrast in silicon could enable low cost and high performance photonic systems, which find many applications in optical communication, data center networking and photonic network-on-chip. This thesis first develops and demonstrates several experimental work on high speed silicon modulators and switches with record performance and novel functionality. A 8x40 Gb/s transmitter based on silicon microrings is first presented. Then an end-to-end link using microrings for Binary Phase Shift Keying (BPSK) modulation and demodulation is shown, and its performance with conventional BPSK modulation/ demodulation techniques is compared. Next, a silicon traveling-wave Mach- Zehnder modulator is demonstrated at data rate up to 56 Gb/s for OOK modulation and 48 Gb/s for BPSK modulation, showing its capability at high speed communication systems. Then a single silicon microring is shown with 2x2 full crossbar switching functionality, enabling optical interconnects with ultra small footprint. Then several other experiments in the silicon platform are presented, including a fully integrated in-band Optical Signal to Noise Ratio (OSNR) monitor, characterization of optical power upper bound in a silicon microring modulator, and wavelength conversion in a dispersion-engineered waveguide. The last part of this thesis is on network-level application of photonics, specically a broadcast-and-select network based on star coupler is introduced, and its scalability performance is studied. Finally a novel switch architecture for data center networks is discussed, and its benefits as a disaggregated network are presented.

  14. The optical module of the Baikal Deep underwater neutrino telescope

    Bagduev, R I; Belolaptikov, I A; Bezrukov, L B; Budnev, N M; Borisovets, B A; Domogatsky, G V; Donskych, L A; Doroshenko, A A; Garus, A A; Golikov, A V; Gluchovskoj, B M; Heller, R; Kabikov, V B; Khripunova, M P; Klabukov, A M; Klimushin, S I; Koshechkin, A P; Kuzmichov, L A; Lisovski, G V; Lubsandorzhiev, B K; Mikolajski, T; Osipova, E A; Pokhil, P G; Pokolev, P A; Putilov, P A; Spiering, C; Stepanenko, Z I; Streicher, O; Thon, T; Vorobev, A A; Wischnewski, R

    1999-01-01

    A deep underwater Cherenkov telescope has been operating since 1993 in stages of growing size at 1.1 km depth in Lake Baikal. The key component of the telescope is the Optical Module (OM) which houses the highly sensitive phototube QUASAR-370. We describe design and parameters of the QUASAR-370, the layout of the optical module, the front-end electronics and the calibration procedures, and present selected results from the five-year operation underwater. Also, future developments with respect to a telescope consisting from several thousand OMs are discussed.

  15. Modulated optical reflectance method for analysis of magnetoelectric nanomaterials

    A recently developed technique of modulated optical reflectance and its applicability to structural and defectoscopic analysis with high spatial resolution of the ferromagnetic LSMO materials is reported. The variation of the optical reflectance is measured within the active area in the laser focus on the surface of the thin film subjected to photothermal modulation. The measurement described is indicative of the magnetoelectric properties of the sample films and is found to be proportional to the thermal variations of the conductance and free carrier density.

  16. Modulated optical reflectance method for analysis of magnetoelectric nanomaterials

    Pencheva, V.; Penchev, S.; Nedkov, I.; Kutzarova, T.; Naboko, V.

    2010-04-01

    A recently developed technique of modulated optical reflectance and its applicability to structural and defectoscopic analysis with high spatial resolution of the ferromagnetic LSMO materials is reported. The variation of the optical reflectance is measured within the active area in the laser focus on the surface of the thin film subjected to photothermal modulation. The measurement described is indicative of the magnetoelectric properties of the sample films and is found to be proportional to the thermal variations of the conductance and free carrier density.

  17. Dynamic behavior and complexity of modulated optical micro ring resonator

    Lei Yang; Wei Pan; Bin Luo; ShuiYing Xiang; Ning Jiang

    2011-01-01

    @@ The dynamic behavior of an optical micro ring resonator (OMRR) with an amplitude modulator positioned in the micro ring is investigated quantitatively by adopting a recently introduced quantifier, the permutation entropy (PE).The effects of modulation depth are focused on, and the roles of input power are considered.The two-dimensional (2D) maps of PE showing dependence on both modulation depth and input power are presented as well.PE values nearly increase with modulation depth.On the other hand, the optimal value of input power is achieved when the PE reaches its maximum.Thus, PE can successfully quantify the dynamics of modulated OMRR.Selecting the parameters in the region with high PE values would contribute to the complexity-enhanced OMRR-based chaotic communication systems.%The dynamic behavior of an optical micro ring resonator (OMRR) with an amplitude modulator positioned in the micro ring is investigated quantitatively by adopting a recently introduced quantifier, the permutation entropy (PE). The effects of modulation depth are focused on, and the roles of input power are considered. The two-dimensional (2D) maps of PE showing dependence on both modulation depth and input power are presented as well. PE values nearly increase with modulation depth. On the other hand, the optimal value of input power is achieved when the PE reaches its maximum. Thus, PE can successfully quantify the dynamics of modulated OMRR. Selecting the parameters in the region with high PE values would contribute to the complexity-enhanced OMRR-based chaotic communication systems.

  18. 20-GHz optical pulse source based on cascaded electroabsorption modulators

    Yuanshan Liu; Jianguo Zhang; Wei Zhao

    2007-01-01

    A high-quality low-timing-jitter 20-GHz optical pulse train is generated by using two cascaded sinusoidally driven electroabsorption modulators (EAMs) at very low bias voltage of -0.8 V in conjunction with a tunable distributed feedback (DFB) semiconductor laser. An approximate transform-limited optical pulse,with the pulse width less than 7 ps, the spectral width of 0.3 nm, and the side-mode suppression ratio (SMSR) above 20 dB, is obtained by tuning the optical delay line.

  19. Analysis of modulated optical reflectance applied to magnetoelectric nanomaterials

    Structural and defectoscopic photothermal analysis of high spatial resolution is performed to sample ferromagnetic LSMO films. The modulated optical reflectance of the surface of the film in the laser focus is indicative of its magnetoelectric properties and is found to be proportional to the thermal variations of free carrier density. (authors)

  20. Comprehensive research on self phase modulation based optical delay systems

    This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres. It researches into the impacts of power level launched into highly nonlinear fibres, conversion wavelength, dispersion slope, modulation format and optical filter bandwidth on the overall performance of optical delay systems. The results reveal that, if the power launched into highly nonlinear fibres is fixed, the time delay generally varies linearly with the conversion wavelength, but jumps intermittently at some conversion wavelengths. However, the time delay varies semi-periodically with the power launched into highly nonlinear fibres. The dispersion slope of highly nonlinear fibres has significant influence on the time delay, especially for the negative dispersion slope. The time delay differs with modulation formats due to the different combined interaction of nonlinearity and dispersion in fibres. The bandwidth of the optical filters also greatly affects the time delay because it determines the bandwidth of the passed signal in the self phase modulation based time delay systems. The output signal quality of the overall time delay systems depends on the conversion wavelength and input power level. The optimisation of the power level and conversion wavelength to provide the best output signal quality is made at the end of this paper

  1. Optical modulation of terahertz pulses in a parallel plate waveguide

    Cooke, David; Jepsen, Peter Uhd

    2008-01-01

    In this work we present a technique for optically modulating a terahertz pulse inside a parallel plate waveguide. A novel semiconductor filled waveguide is formed by coating both sides of a thin, high resistivity silicon slab with a transparent conducting oxide. While the waveguide is intrinsically...

  2. The KM3NeT Digital Optical Module

    Vivolo, Daniele

    2016-04-01

    KM3NeT is a European deep-sea multidisciplinary research infrastructure in the Mediterranean Sea. It will host a km3-scale neutrino telescope and dedicated instruments for long-term and continuous measurements for Earth and Sea sciences. The KM3NeT neutrino telescope is a 3-dimensional array of Digital Optical Modules, suspended in the sea by means of vertical string structures, called Detection Units, supported by two pre-stretched Dyneema ropes, anchored to the seabed and kept taut with a system of buoys. The Digital Optical Module represents the active part of the neutrino telescope. It is composed by a 17-inch, 14 mm thick borosilicate glass (Vitrovex) spheric vessel housing 31 photomultiplier tubes with 3-inch photocathode diameter and the associated front-end and readout electronics. The technical solution adopted for the KM3NeT optical modules is characterized by an innovative design, considering that existing neutrino telescopes, Baikal, IceCube and ANTARES, all use large photomultipliers, typically with a diameter of 8″ or 10″. It offers several advantages: higher sensitive surface (1260 cm2), weaker sensitivity to Earth's magnetic field, better distinction between single-photon and multi-photon events (photon counting) and directional information with an almost isotropic field of view. In this contribution the design and the performance of the KM3NeT Digital Optical Modules are discussed, with a particular focus on enabling technologies and integration procedure.

  3. Comprehensive research on self phase modulation based optical delay systems

    Yang Ai-Ying; Sun Yu-Nan

    2010-01-01

    This paper comprehensively investigates the properties of self phase modulation based optical delay systems consisting of dispersion compensation fibre and highly nonlinear fibres.It researches into the impacts of power level launched into highly nonlinear fibres,conversion wavelength,dispersion slope,modulation format and optical filter bandwidth on the overall performance of optical delay systems.The results reveal that,if the power launched into highly nonlinear fibres is fixed,the time delay generally varies linearly with the conversion wavelength,but jumps intermittently at some conversion wavelengths.However,the time delay varies semi-periodically with the power launched into highly nonlinear fibres.The dispersion slope of highly nonlinear fibres has significant influence on the time delay,especially for the negative dispersion slope.The time delay differs with modulation formats due to the different combined interaction of nonlinearity and dispersion in fibres.The bandwidth of the optical filters also greatly affects the time delay because it determines the bandwidth of the passed signal in the self phase modulation based time delay systems.The output signal quality of the overall time delay systems depends on the conversion wavelength and input power level.The optimisation of the power level and conversion wavelength to provide the best output signal quality is made at the end of this paper.

  4. 30 GHz Zeno-based Graphene Electro-optic Modulator

    Phare, Christopher T; Cardenas, Jaime; Lipson, Michal

    2014-01-01

    Graphene has generated exceptional interest as an optoelectronic material because its high carrier mobility and broadband absorption promise to make extremely fast and broadband electro-optic devices possible. Electro-optic graphene modulators reported to date, however, have been limited in bandwidth to a few GHz because of the large capacitance required to achieve reasonable voltage swings. Here we demonstrate a graphene electro-optic modulator based on the classical Zeno effect that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth, over an order of magnitude faster than prior work, and a state-of-the-art modulation efficiency of 1.5 dB/V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and n...

  5. All-optical Demultiplexing Using an Electroabsorption Modulator

    Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

    1999-01-01

    In the last decade, the electroabsorption modulator (EAM) (essentially a reverse biased semiconductor optical amplifier) has found an increasingly wider range of applications within optical communications, although mostly at the research level. Recently, all-optical signal-processing such as...... wavelength conversion, demultiplexing, and signal regeneration using an EAM have also been experimentally demonstrated, and lately theoretical calculations of wavelength conversion and signal regeneration have been presented. These functionalities are important for constructing ultrahigh-speed all......-optical networks.Here, we present modeling results of all-optical demultiplexing from 80 to 10 Gbit/s using an EAM. Our large-signal model for the reverse-biased quantum well absorber is based on a detailed gain model, and was originally developed for studying colliding-pulse mode-locked lasers. Sweep-out of photo...

  6. Laser pulse spectral shaping based on electro-optic modulation

    Yanhai Wang; Jiangfeng Wang; You'en Jiang; Yan Bao; Xuechun Li; Zunqi Lin

    2008-01-01

    A new spectrum shaping method, based on electro-optic modulation, to alleviate gain narrowing in chirped pulse amplification (CPA) system, is described and numerically simulated. Near-Fourier transform-limited seed laser pulse is chirped linearly through optical stretcher. Then the chirped laser pulse is coupled into integrated waveguide electro-optic modulator driven by an aperture-coupled-stripline (ACSL) electricalwaveform generator, and the pulse shape and amplitude are shaped in time domain. Because of the directrelationship between frequency interval and time interval of the linearly chirped pulse, the laser pulse spectrum is shaped correspondingly. Spectrum-shaping examples are modeled numerically to determine the spectral resolution of this technique. The phase error introduced in this method is also discussed.

  7. SCALE FACTOR DETERMINATION METHOD OF ELECTRO-OPTICAL MODULATOR IN FIBER-OPTIC GYROSCOPE

    A. S. Aleynik

    2016-05-01

    Full Text Available Subject of Research. We propose a method for dynamic measurement of half-wave voltage of electro-optic modulator as part of a fiber optic gyroscope. Excluding the impact of the angular acceleration o​n measurement of the electro-optical coefficient is achieved through the use of homodyne demodulation method that allows a division of the Sagnac phase shift signal and an auxiliary signal for measuring the electro-optical coefficient in the frequency domain. Method. The method essence reduces to decomposition of step of digital serrodyne modulation in two parts with equal duration. The first part is used for quadrature modulation signals. The second part comprises samples of the auxiliary signal used to determine the value of the scale factor of the modulator. Modeling is done in standalone model, and as part of a general model of the gyroscope. The applicability of the proposed method is investigated as well as its qualitative and quantitative characteristics: absolute and relative accuracy of the electro-optic coefficient, the stability of the method to the effects of angular velocities and accelerations, method resistance to noise in actual devices. Main Results. The simulation has showed the ability to measure angular velocity changing under the influence of angular acceleration, acting on the device, and simultaneous measurement of electro-optical coefficient of the phase modulator without interference between these processes. Practical Relevance. Featured in the paper the ability to eliminate the influence of the angular acceleration on the measurement accuracy of the electro-optical coefficient of the phase modulator will allow implementing accurate measurement algorithms for fiber optic gyroscopes resistant to a significant acceleration in real devices.

  8. CPV module with Fresnel lens primary optics and homogenizing secondary optics

    Wiesenfarth, Maike; Dörsam, Tobias; Eltermann, Fabian; Hornung, Thorsten; Siefer, Gerald; Steiner, Marc; van Riesen, Sascha; Neubauer, Martin; Boos, Alexander; Wanka, Sven; Gombert, Andreas; Bett, Andreas W.

    2015-09-01

    In this work CPV modules based on Fresnel lenses and using refractive secondary optical elements (SOEs) are investigated. Pure silicone as well as glass SOEs glued on top of the solar cells are explored in prototype modules. They are differently manufactured in respect to how the secondary optics was assembled. For example, units with secondary silicone optics directly casted to solar cells are manufactured. For a design of glued glass optics and Fresnel lenses, the optical design is analyzed experimentally. Moreover, the long term stability has been intensively tested by accelerated aging tests and outdoor experiments. Here, the focus was on the used silicone material and the adhesion of the silicone to the glass interface.

  9. Optical pulse compression reflectometry based on single-sideband modulator driven by electrical frequency-modulated pulse

    Zou, Weiwen; Yu, Lei; Yang, Shuo; Chen, Jianping

    2016-05-01

    We propose a novel scheme to generate a linear frequency-modulated optical pulse with high extinction ratio based on an electrical frequency-modulated pulse and optical single-sideband modulator. This scheme is proved to improve the stability and accuracy of optical pulse compression reflectometry (OPCR). In the experiment, a high spatial resolution of 10 cm and a long measurement range of 10.8 km using a laser source with 2-km coherence length are demonstrated.

  10. Evaluation of Geometrical Modulation Transfer Function in Optical Lens System

    Cheng-Mu Tsai

    2015-01-01

    Full Text Available This paper presents ray tracing algorithms to evaluate the geometrical modulation transfer function (GMTF of optical lens system. There are two kinds of ray tracings methods that can be applied to help simulate the point spread function (PSF in the image plane, for example, paraxial optics and real ray tracings. The paraxial optics ray tracing is used to calculate the first-order properties such as the effective focal length (EFL and the entrance pupil position through less cost of computation. However, the PSF could have a large tolerance by only using paraxial optics ray tracing for simulation. Some formulas for real ray tracing are applied in the sagittal and tangential line spread function (LSF. The algorithms are developed to demonstrate the simulation of LSF. Finally, the GMTF is evaluated after the fast Fourier transform (FFT of the LSF.

  11. Optical metrology for advanced process control: full module metrology solutions

    Bozdog, Cornel; Turovets, Igor

    2016-03-01

    Optical metrology is the workhorse metrology in manufacturing and key enabler to patterning process control. Recent advances in device architecture are gradually shifting the need for process control from the lithography module to other patterning processes (etch, trim, clean, LER/LWR treatments, etc..). Complex multi-patterning integration solutions, where the final pattern is the result of multiple process steps require a step-by-step holistic process control and a uniformly accurate holistic metrology solution for pattern transfer for the entire module. For effective process control, more process "knobs" are needed, and a tighter integration of metrology with process architecture.

  12. Interactive online optics modules for the college physics course

    Hoeling, Barbara M.

    2012-04-01

    A new learning tool for geometrical optics is presented which has been developed for an algebra based introductory college physics course for life science majors. The interactive online learning module contains images, videos of problem solutions, short animated videos, and interactive animations, which allow students to actively explore the physics content beyond the pictures in a textbook. These elements are accompanied by narration and a transcript to guide the students while allowing them to navigate freely between the different parts of the module. The results of student learning, a comparison with a control group, and a survey of student attitudes toward this new instruction method are discussed.

  13. Ultrasound-Modulated Optical Tomography in Reflective and Coaxial Configuration

    傅洪波; 邢达; 曾亚光; 王毅; 陈群

    2003-01-01

    Ultrasound-modulated optical tomography affords a very promising noninvasive imaging method for biomedical diagnosis. With this technique, an ultrasound beam is focused into a scattering medium to provide an accurate localization and, simultaneously, a modulation of laser light inside the medium. Based on the high-sensitivity detection technique, we have developed a unique reflective configuration, which was more convenient and practical than other existing configurations. Furthermore, the configuration also introduced a new scheme to improve the spatial resolution in the imaging. A phantom was imaged to validate the feasibility of the proposed configuration.

  14. Optical module to extend any Fourier-domain optical coherence tomography system into a polarisation-sensitive system

    Rivet, Sylvain; Marques, Manuel J.; Bradu, Adrian; Podoleanu, Adrian

    2016-06-01

    This article presents a theoretical study on an optical module (OM) that can be inserted between an object under investigation and a Fourier-domain optical coherence tomography system, transforming the latter into a polarisation-sensitive optical coherence tomography optical coherence tomography (OCT) system. The module consists of two electro-optic modulators, a Faraday rotator, a linear polariser and a quarter-wave plate. A detailed description on how the module can be used to extract both the net retardance and the fast axis orientation of a linear birefringent sample is presented. This is achieved by taking two sequential measurements for different values of retardance produced by the electro-optic modulator. The module keeps measurements free from undesired polarimetric effects due to birefringence in the single-mode optical fibre and diattenuation in fibre-based couplers within OCT systems. Simulations have been carried out in order to evaluate the effects of chromatic behaviour of the components within the OM.

  15. Phase-coherent orthogonally polarized optical single sideband modulation with arbitrarily tunable optical carrier-to-sideband ratio.

    Wang, Wen Ting; Liu, Jian Guo; Mei, Hai Kuo; Zhu, Ning Hua

    2016-01-11

    We propose and experimentally verify a novel approach to achieve phase-coherence orthogonally polarized optical single sideband (OSSB) modulation with a tunable optically carrier-to-sideband ratio (OCSR). In our scheme, the orthogonally polarized OSSB signal is achieved using a dual-polarization quadrature phase shift keying (DP-QPSK) modulator without an optical band-pass filter (OBPF). Therefore, the proposed method is wavelength independent. The DP-QPSK modulator includes two parallel QPSK modulators locating on its two arms. The upper QPSK modulator of the DP-QPSK modulator is driven by two quadrature sinusoidal microwave signals and works at the frequency shifting condition whose bias voltages are optimized to suppress the optical. The lower QPSK modulator of that works at the maximum transmission point and the optical carrier is not modulated. The OCSR is continuously tunable by simply adjusting the bias voltages of the lower modulator. The frequency shifting optical signal from the upper QPSK modulator and the optical carrier from the lower QPSK modulator are combined together at the output of the DP-QPSK modulator. The optical carrier and sideband are polarized orthogonally. The generated OSSB signals could be used to shift and code the phase of the microwave signal and generate ultra-wideband (UWB) microwave pulse. The proposed method is analyzed and experimental demonstrated. PMID:26832269

  16. Testing the precision optical calibration module for PINGU

    The Precision IceCube Next Generation Upgrade (PINGU) is primarily designed to determine the neutrino mass hierarchy. This measurement requires an accurate calibration of the detector in order to reduce systematic uncertainties. The Precision Optical Calibration Modules (POCAM) will be placed in the detector as a well calibrated artificial light source in the ice. The POCAM will be enclosed in a glass sphere identical to those used for the detector modules. To construct and simulate a prototype of the POCAM, every component needs to be analyzed by their optical characteristics and by the behavior in temperatures down to -50 C. Therefore a highly shielded an isolated environment has to be build up. We report the status of the testing environment and the hardware selected.

  17. The KM3NeT Digital Optical Module

    Vivolo Daniele

    2016-01-01

    Full Text Available KM3NeT is a European deep-sea multidisciplinary research infrastructure in the Mediterranean Sea. It will host a km3-scale neutrino telescope and dedicated instruments for long-term and continuous measurements for Earth and Sea sciences. The KM3NeT neutrino telescope is a 3-dimensional array of Digital Optical Modules, suspended in the sea by means of vertical string structures, called Detection Units, supported by two pre-stretched Dyneema ropes, anchored to the seabed and kept taut with a system of buoys. The Digital Optical Module represents the active part of the neutrino telescope. It is composed by a 17-inch, 14 mm thick borosilicate glass (Vitrovex spheric vessel housing 31 photomultiplier tubes with 3-inch photocathode diameter and the associated front-end and readout electronics. The technical solution adopted for the KM3NeT optical modules is characterized by an innovative design, considering that existing neutrino telescopes, Baikal, IceCube and ANTARES, all use large photomultipliers, typically with a diameter of 8″ or 10″. It offers several advantages: higher sensitive surface (1260 cm2, weaker sensitivity to Earth's magnetic field, better distinction between single-photon and multi-photon events (photon counting and directional information with an almost isotropic field of view. In this contribution the design and the performance of the KM3NeT Digital Optical Modules are discussed, with a particular focus on enabling technologies and integration procedure.

  18. Optical Characterization of Different Thin Film Module Technologies

    R. Ebner

    2015-01-01

    Full Text Available For a complete quality control of different thin film module technologies (a-Si, CdTe, and CIS a combination of fast and nondestructive methods was investigated. Camera-based measurements, such as electroluminescence (EL, photoluminescence (PL, and infrared (IR technologies, offer excellent possibilities for determining production failures or defects in solar modules which cannot be detected by means of standard power measurements. These types of optical measurement provide high resolution images with a two-dimensional distribution of the characteristic features of PV modules. This paper focuses on quality control and characterization using EL, PL, and IR imaging with conventional cameras and an alternative excitation source for the PL-setup.

  19. Modulational instability in nonlinearity-managed optical media

    We investigate analytically, numerically, and experimentally the modulational instability in a layered, cubically nonlinear (Kerr) optical medium that consists of alternating layers of glass and air. We model this setting using a nonlinear Schroedinger (NLS) equation with a piecewise constant nonlinearity coefficient and conduct a theoretical analysis of its linear stability, obtaining a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between the theoretical analysis of the Kronig-Penney equation, numerical simulations of the NLS equation, and the experimental results for the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, we find multiple instability regions rather than just the one that would occur in uniform media

  20. Generalized model for all-optical light modulation in bacteriorhodopsin

    Roy, Sukhdev; Singh, C. P.; Reddy, K. P. J.

    2001-10-01

    We present a generalized model for the photochemical cycle of bacteriorhodopsin (bR) protein molecule. Rate equations have been solved for the detailed light-induced processes in bR for its nine states: B→K↔L↔MI→MII↔N↔O↔P→Q→B. The complete steady-state intensity-induced population densities in various states of the molecule have been computed to obtain a general, exact, and analytical expression for the nonlinear absorption coefficient for multiple modulation pump laser beams. All-optical light modulation of different probe laser beam transmissions by intensity induced population changes due to one and two modulation laser beams has been analyzed. The proposed model has been shown to accurately model experimental results.

  1. Optical modulation of quantum cascade laser with optimized excitation wavelength.

    Yang, Tao; Chen, Gang; Tian, Chao; Martini, Rainer

    2013-04-15

    The excitation wavelength for all-optical modulation of a 10.6 μm mid-infrared (MIR) quantum cascade laser (QCL) was varied in order to obtain maximum modulation depth. Both amplitude and wavelength modulation experiments were conducted at 820 nm and 1550 nm excitation respectively, whereby the latter matches the interband transition in the QCL active region. Experimental results show that for continuous-wave mode-operated QCL, the efficiency of free carrier generation is doubled under 1550 nm excitation compared with 820 nm excitation, resulting in an increase of the amplitude modulation index from 19% to 36%. At the same time, the maximum wavelength shift is more than doubled from 1.05 nm to 2.80 nm. Furthermore, for the first time to our knowledge, we demonstrated the optical switching of a QCL operated in pulse mode by simple variation of the excitation wavelength. PMID:23595430

  2. Residual intensity modulation in resonator fiber optic gyros with sinusoidal wave phase modulation

    Di-qing YING; Qiang LI; Hui-lian MA; Zhong-he JIN

    2014-01-01

    We present how residual intensity modulation (RIM) affects the performance of a resonator fiber optic gyro (R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system’s demodulation curve under RIM is obtained. Through numerical simulation with different RIM coefficients and modulation frequencies, we find that a zero deviation is induced by the RIM effect on the demodulation curve, and this zero deviation varies with the RIM coefficient and modulation frequency. The expression for the system error due to this zero deviation is derived. Simulation results show that the RIM-induced error varies with the RIM coefficient and modulation frequency. There also exists optimum values for the RIM coefficient and modulation frequency to totally eliminate the RIM-induced error, and the error increases as the RIM coefficient or modulation frequency deviates from its optimum value;however, in practical situations, these two parameters would not be exactly fixed but fluctuate from their respective optimum values, and a large system error is induced even if there exists a very small deviation of these two critical parameters from their optimum values. Simulation results indicate that the RIM-induced error should be con-sidered when designing and evaluating an R-FOG system.

  3. Parallel optical interconnects utilizing VLSI/FLC spatial light modulators

    Genco, Sheryl M.

    1991-12-01

    Interconnection architectures are a cornerstone of parallel computing systems. However, interconnections can be a bottleneck in conventional computer architectures because of queuing structures that are necessary to handle the traffic through a switch at very high data rates and bandwidths. These issues must find new solutions to advance the state of the art in computing beyond the fundamental limit of silicon logic technology. Today's optoelectronic (OE) technology in particular VLSI/FLC spatial light modulators (SLMs) can provide a unique and innovative solution to these issues. This paper reports on the motivations for the system, describes the major areas of architectural requirements, discusses interconnection topologies and processor element alternatives, and documents an optical arbitration (i.e., control) scheme using `smart' SLMs and optical logic gates. The network topology is given in section 2.1 `Architectural Requirements -- Networks,' but it should be noted that the emphasis is on the optical control scheme (section 2.4) and the system.

  4. Breaking the energy-bandwidth limit of electro-optic modulators: theory and a device proposal

    Lin, Hongtao; Liu, Jifeng; Zhang, Lin; Michel, Jurgen; Hu, Juejun

    2013-01-01

    In this paper, we quantitatively analyzed the trade-off between energy per bit for switching and modulation bandwidth of classical electro-optic modulators. A formally simple energy-bandwidth limit (Eq. 10) is derived for electro-optic modulators based on intra-cavity index modulation. To overcome this limit, we propose a dual cavity modulator device which uses a coupling modulation scheme operating at high bandwidth (> 200 GHz) not limited by cavity photon lifetime and simultaneously features an ultra-low switching energy of 0.26 aJ, representing over three orders of magnitude energy consumption reduction compared to state-of-the-art electro-optic modulators.

  5. Polymeric Optical Code-Division Multiple-Access (CDMA Encoder and Decoder Modules

    Ray T. Chen

    2011-09-01

    Full Text Available We propose a low cost polymeric optical waveguides-based optical CDMA encoder and decoder modules. The structures of the optical CDMA encoder and decoder modules are presented. The performance of the optical CDMA encoder and decoder modules is simulated using 10-chip binary phase-shift keying (BPSK coding schemes. The optical CDMA encoder and decoder modules can effectively transmit and recover optical CDMA data streams. The SNR of the received signal is analyzed and determined to be primarily from the cross correlation with other channels.

  6. Research of transmission and reception modules of open optical communication system

    The results of studying characteristics of optical signal's transmission module's in the voltage region 3-9 V are presented. It was experimentally shown that by introducing the rectifier diode to the modulating cascade of the modulator between base and emitter the linear increase of the optical output signal is obtained. Application of double-barrier photodiode with effect of amplification of primary photocurrent with voltage provides the proper operation of receiver module from a weak optical signal. (authors)

  7. PV Optics: An Optical Modeling Tool for Solar Cell and Module Design; Preprint

    A brief description of the capabilities of PV Optics, a software package for the design and analysis of solar cells and modules, is given. Some specific applications of the software for the design of thick- and thin-film cells are given

  8. BPSK optical mm-wave signal generation by septupling frequency via a single optical phase modulator

    Wu, Peng; Ma, Jianxin

    2016-09-01

    In this paper, we have proposed a novel and simple scheme to generate the BPSK optical millimeter wave (MMW) signal with frequency septupling by using an optical phase modulator (PM) and a wavelength selective switch (WSS). In this scheme, the PM is driven by a radio frequency (RF) BPSK signal at the optimized modulation index of 4.89 to assure the 4th and 3rd-order sidebands have equal amplitudes. An wavelength selective switch (WSS) is used to abstract the -4th and +3rd-order sidebands from the spectrum generated by RF BPSK signal modulating the lightwave to form the BPSK optical MMW signal with frequency septupling the driving RF signal. In these two tones, only the +3rd-order sideband bears the BPSK signal while the -4th-order sideband is unmodulated since the phase information is canceled by the even times multiplication of the phase of BPSK signal. The MMW signal can avoid the pulse walk-off effect and the amplitude fading effect caused by the fiber chromatic dispersion. By adjusting the modulation index to assure the two tones have equal amplitude, the generated optical MMW signal has the maximal opto-electrical conversion efficiency and good transmission performance.

  9. Influence of SiO2/In2O3 film acoustical waveguide on the mode index of Ti:LiNbO3 optical waveguide in acousto-optical mode converter

    Lin, Hang-you; Ning, Ji-ping; Geng, Fan

    2004-04-01

    TE/TM mode converter is a key element of integrated acoustooptical tunable filter (AOTF). Employing SiO2/In2O3 film as acoustical waveguide can suppress sidelobes effectively and simplify fabrication technique in integrated quasi-collinear AOTF. In this report, the eigenvalue equation and the field solution of such configuration has been obtained by using modified Wenzel-Kramers-Brillouin (WKB) method. The results are compared with those by using vector finite element method (VFEM). When the optical waveguides are covered by such oxide film, the difference of mode indices of both polarizations and the effective propagation velocity of surface acoustical wave (SAW) will decrease, and these decreases lead the shift of optical wavelength, which mainly results in the change of the former.

  10. Dynamic optical modulation of an electron beam on a photocathode RF gun: Toward intensity-modulated radiation therapy (IMRT)

    In intensity-modulated radiation therapy (IMRT), the aim is to deliver reduced doses of radiation to normal tissue. As a step toward IMRT, we examined dynamic optical modulation of an electron beam produced by a photocathode RF gun. Images on photomasks were transferred onto a photocathode by relay imaging. The resulting beam was controlled by a remote mirror. The modulated electron beam maintained its shape on acceleration, had a fine spatial resolution, and could be moved dynamically by optical methods