Sample records for zgp optical parametric

  1. High power far-infrared optical parametric oscillator with high beam quality

    NASA Astrophysics Data System (ADS)

    Qian, Chuan-Peng; Shen, Ying-Jie; Dai, Tong-Yu; Duan, Xiao-Ming; Yao, Bao-Quan

    2016-11-01

    A high power ZnGeP2 (ZGP) optical parametric oscillator (OPO) with good beam quality pumped by a Q-switched Ho:YAG laser was demonstrated. The maximum output power of the ZGP OPO with a four-mirror ring cavity was about 5.04 W around 8.1 μm with 83.9 W Ho incident pump power, corresponding to a slope efficiency of 9.2 %. The ZGP OPO produced 36.0 ns far-IR pulse laser in the 8.0-8.3 μm spectral regions. The beam quality was measured to be M2 1.6 at the highest output power.

  2. Mid-infrared ZGP OPO with divergence compensation and high beam quality.

    PubMed

    Schellhorn, Martin; Spindler, Gerhard; Eichhorn, Marc

    2018-01-22

    Divergence compensation, optimization of the optical-to-optical efficiency, and high beam quality of signal and idler beams of a high-energy mid-infrared ZnGeP 2 (ZGP) optical parametric oscillator (OPO) have been demonstrated by use of a Galilean telescope inside the nonplanar fractional-image-rotation enhancement (FIRE) ring resonator. With a small variation of the distance between the lenses of the telescope, the divergences of signal and idler beams could be adjusted. Up to 36 mJ of mid-infrared pulse energy in the 3-5 µm wavelength range is obtained with 92 mJ of pump energy on crystal. The beam quality factors M 2 are < 1.5 for the resonant signal beam and the non-resonant idler beam, respectively. Actually, this is an improvement of the beam quality by a factor 3 for the signal and ~2.7 for the idler beam compared without using a telescope inside the FIRE ring resonator.

  3. Towards Terawatt Sub-Cycle Long-Wave Infrared Pulses via Chirped Optical Parametric Amplification and Indirect Pulse Shaping

    PubMed Central

    Yin, Yanchun; Chew, Andrew; Ren, Xiaoming; Li, Jie; Wang, Yang; Wu, Yi; Chang, Zenghu

    2017-01-01

    We present an approach for both efficient generation and amplification of 4–12 μm pulses by tailoring the phase matching of the nonlinear crystal Zinc Germanium Phosphide (ZGP) in a narrowband-pumped optical parametric chirped pulse amplifier (OPCPA) and a broadband-pumped dual-chirped optical parametric amplifier (DC-OPA), respectively. Preliminary experimental results are obtained for generating 1.8–4.2 μm super broadband spectra, which can be used to seed both the signal of the OPCPA and the pump of the DC-OPA. The theoretical pump-to-idler conversion efficiency reaches 27% in the DC-OPA pumped by a chirped broadband Cr2+:ZnSe/ZnS laser, enabling the generation of  Terawatt-level 4–12 μm pulses with an available large-aperture ZGP. Furthermore, the 4–12 μm idler pulses can be compressed to sub-cycle pulses by compensating the tailored positive chirp of the idler pulses using the bulk compressor NaCl, and by indirectly controlling the higher-order idler phase through tuning the signal (2.4–4.0 μm) phase with a commercially available acousto-optic programmable dispersive filter (AOPDF). A similar approach is also described for generating high-energy 4–12 μm sub-cycle pulses via OPCPA pumped by a 2 μm Ho:YLF laser. PMID:28367966

  4. 99 W mid-IR operation of a ZGP OPO at 25% duty cycle.

    PubMed

    Hemming, Alexander; Richards, Jim; Davidson, Alan; Carmody, Neil; Bennetts, Shayne; Simakov, Nikita; Haub, John

    2013-04-22

    We have demonstrated the highest reported output power from a mid-IR ZGP OPO. The laser is a cascaded hybrid system consisting of a thulium fibre laser, Ho:YAG solid state laser and a Zinc Germanium Phosphide parametric oscillator. The system produces 27 W of output power in the 3-5 μm wavelength range with an M(2) = 4.0 when operating in a repetitively q-switched mode, and a modulated peak output power of 99 W at a reduced duty cycle of 25%.

  5. High peak-power mid-infrared ZnGeP₂ optical parametric oscillator pumped by a Tm:fiber master oscillator power amplifier system.

    PubMed

    Gebhardt, Martin; Gaida, Christian; Kadwani, Pankaj; Sincore, Alex; Gehlich, Nils; Jeon, Cheonha; Shah, Lawrence; Richardson, Martin

    2014-03-01

    We report on the utilization of a novel Tm:fiber laser source for mid-IR ZnGeP2 (ZGP) optical parametric oscillator (OPO) pumping. The pump laser is built in a master oscillator power-amplifier configuration delivering up to 3.36 W of polarized, diffraction limited output power with 7 ns pulse duration and 4 kHz repetition rate. This corresponds to a peak power of ∼121  kW and a pulse energy of ∼0.84  mJ. With this source, we generated 27.9 kW of total mid-IR peak power in a doubly resonant oscillator (DRO) configuration. This is, to the best of our knowledge, the highest ever demonstrated mid-IR peak power from a directly Tm:fiber laser pumped ZGP OPO. Moreover, a DRO output with about 284 μJ of total mid-IR pulse energy was demonstrated using 100 ns pump pulses. The wavelength tuning of the idler was extended to 6 μm with lower output power in another OPO experiment.

  6. Self-seeding ring optical parametric oscillator

    DOEpatents

    Smith, Arlee V [Albuquerque, NM; Armstrong, Darrell J [Albuquerque, NM

    2005-12-27

    An optical parametric oscillator apparatus utilizing self-seeding with an external nanosecond-duration pump source to generate a seed pulse resulting in increased conversion efficiency. An optical parametric oscillator with a ring configuration are combined with a pump that injection seeds the optical parametric oscillator with a nanosecond duration, mJ pulse in the reverse direction as the main pulse. A retroreflecting means outside the cavity injects the seed pulse back into the cavity in the direction of the main pulse to seed the main pulse, resulting in higher conversion efficiency.

  7. Injection-seeded optical parametric oscillator and system

    DOEpatents

    Lucht, Robert P.; Kulatilaka, Waruna D.; Anderson, Thomas N.; Bougher, Thomas L.

    2007-10-09

    Optical parametric oscillators (OPO) and systems are provided. The OPO has a non-linear optical material located between two optical elements where the product of the reflection coefficients of the optical elements are higher at the output wavelength than at either the pump or idler wavelength. The OPO output may be amplified using an additional optical parametric amplifier (OPA) stage.

  8. Gated frequency-resolved optical imaging with an optical parametric amplifier

    DOEpatents

    Cameron, Stewart M.; Bliss, David E.; Kimmel, Mark W.; Neal, Daniel R.

    1999-01-01

    A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media.

  9. Gated frequency-resolved optical imaging with an optical parametric amplifier

    DOEpatents

    Cameron, S.M.; Bliss, D.E.; Kimmel, M.W.; Neal, D.R.

    1999-08-10

    A system for detecting objects in a turbid media utilizes an optical parametric amplifier as an amplifying gate for received light from the media. An optical gating pulse from a second parametric amplifier permits the system to respond to and amplify only ballistic photons from the object in the media. 13 figs.

  10. Parametric Amplification For Detecting Weak Optical Signals

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Chen, Chien; Chakravarthi, Prakash

    1996-01-01

    Optical-communication receivers of proposed type implement high-sensitivity scheme of optical parametric amplification followed by direct detection for reception of extremely weak signals. Incorporates both optical parametric amplification and direct detection into optimized design enhancing effective signal-to-noise ratios during reception in photon-starved (photon-counting) regime. Eliminates need for complexity of heterodyne detection scheme and partly overcomes limitations imposed on older direct-detection schemes by noise generated in receivers and by limits on quantum efficiencies of photodetectors.

  11. (012)-cut chalcopyrite ZnGeP2 as a high-bandwidth terahertz electro-optic detection crystal

    NASA Astrophysics Data System (ADS)

    Carnio, B. N.; Greig, S. R.; Firby, C. J.; Zawilski, K. T.; Schunemann, P. G.; Elezzabi, A. Y.

    2017-02-01

    The detection properties of a chalcopyrite zinc germanium diphosphide (ZnGeP2, ZGP) electro-optic (EO) crystal, having thickness of 1080 μm and cut along the <012> plane, is studied in the terahertz (THz) frequency range. Outstanding phase matching is achieved between the optical probe pulse and the THz frequency components, leading to a large EO detection bandwidth. ZGP has the ability to measure frequencies that are 1.3 and 1.2 times greater than that of ZnTe for crystal thicknesses of 1080 and 500 μm, respectively. Furthermore, the ZGP crystal is able to detect frequency components that are >=4.6 times larger than both ZnSe and GaP (for crystal thicknesses of 1080 μm) and >=2.2 times larger than ZnSe and GaP (for crystal thicknesses of 500 μm).

  12. Raman-Suppressing Coupling for Optical Parametric Oscillator

    NASA Technical Reports Server (NTRS)

    Savchenkov, Anatoliy; Maleki, Lute; Matsko, Andrey; Rubiola, Enrico

    2007-01-01

    A Raman-scattering-suppressing input/ output coupling scheme has been devised for a whispering-gallery-mode optical resonator that is used as a four-wave-mixing device to effect an all-optical parametric oscillator. Raman scattering is undesired in such a device because (1) it is a nonlinear process that competes with the desired nonlinear four-wave conversion process involved in optical parametric oscillation and (2) as such, it reduces the power of the desired oscillation and contributes to output noise. The essence of the present input/output coupling scheme is to reduce output loading of the desired resonator modes while increasing output loading of the undesired ones.

  13. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    NASA Astrophysics Data System (ADS)

    Isaienko, Oleksandr; Robel, István

    2016-03-01

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7-20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.

  14. Ghost imaging via optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Li, Hong-Guo; Zhang, De-Jian; Xu, De-Qin; Zhao, Qiu-Li; Wang, Sen; Wang, Hai-Bo; Xiong, Jun; Wang, Kaige

    2015-10-01

    We investigate theoretically and experimentally thermal light ghost imaging where the light transmitted through the object as the seed light is amplified by an optical parametric amplifier (OPA). In conventional lens imaging systems with OPA, the spectral bandwidth of OPA dominates the image resolution. Theoretically, we prove that in ghost imaging via optical parametric amplification (GIOPA) the bandwidth of OPA will not affect the image resolution. The experimental results show that for weak seed light the image quality in GIOPA is better than that of conventional ghost imaging. Our work may be valuable in remote sensing with ghost imaging technique, where the light passed through the object is weak after a long-distance propagation.

  15. Optical parametric amplification and oscillation assisted by low-frequency stimulated emission.

    PubMed

    Longhi, Stefano

    2016-04-15

    Optical parametric amplification and oscillation provide powerful tools for coherent light generation in spectral regions inaccessible to lasers. Parametric gain is based on a frequency down-conversion process and, thus, it cannot be realized for signal waves at a frequency ω3 higher than the frequency of the pump wave ω1. In this Letter, we suggest a route toward the realization of upconversion optical parametric amplification and oscillation, i.e., amplification of the signal wave by a coherent pump wave of lower frequency, assisted by stimulated emission of the auxiliary idler wave. When the signal field is resonated in an optical cavity, parametric oscillation is obtained. Design parameters for the observation of upconversion optical parametric oscillation at λ3=465 nm are given for a periodically poled lithium-niobate (PPLN) crystal doped with Nd(3+) ions.

  16. Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers

    DOE PAGES

    Isaienko, Oleksandr; Robel, Istvan

    2016-03-15

    Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to themore » oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ (2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. Furthermore, the pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations P NL of the impulsively excited phonons and those of parametrically amplified waves.« less

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

    PubMed

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

    2018-04-16

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

  18. Three-wave interaction solitons in optical parametric amplification.

    PubMed

    Ibragimov, E; Struthers, A A; Kaup, D J; Khaydarov, J D; Singer, K D

    1999-05-01

    This paper applies three-wave interaction (TWI)-soliton theory to optical parametric amplification when the signal, idler, and pump wave can all contain TWI solitons. We use an analogy between two different velocity regimes to compare the theory with output from an experimental synchronously pumped optical parametric amplifier. The theory explains the observed inability to compress the intermediate group-velocity wave and 20-fold pulse compression in this experiment. The theory and supporting numerics show that one can effectively control the shape and energy of the optical pulses by shifting the TWI solitons in the pulses.

  19. Wavelength-doubling optical parametric oscillator

    DOEpatents

    Armstrong, Darrell J [Albuquerque, NM; Smith, Arlee V [Albuquerque, NM

    2007-07-24

    A wavelength-doubling optical parametric oscillator (OPO) comprising a type II nonlinear optical medium for generating a pair of degenerate waves at twice a pump wavelength and a plurality of mirrors for rotating the polarization of one wave by 90 degrees to produce a wavelength-doubled beam with an increased output energy by coupling both of the degenerate waves out of the OPO cavity through the same output coupler following polarization rotation of one of the degenerate waves.

  20. Ultra-Broad-Band Optical Parametric Amplifier or Oscillator

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

    A concept for an ultra-broad-band optical parametric amplifier or oscillator has emerged as a by-product of a theoretical study in fundamental quantum optics. The study was originally intended to address the question of whether the two-photon temporal correlation function of light [in particular, light produced by spontaneous parametric down conversion (SPDC)] can be considerably narrower than the inverse of the spectral width (bandwidth) of the light. The answer to the question was found to be negative. More specifically, on the basis of the universal integral relations between the quantum two-photon temporal correlation and the classical spectrum of light, it was found that the lower limit of two-photon correlation time is set approximately by the inverse of the bandwidth. The mathematical solution for the minimum two-photon correlation time also provides the minimum relative frequency dispersion of the down-converted light components; in turn, the minimum relative frequency dispersion translates to the maximum bandwidth, which is important for the design of an ultra-broad-band optical parametric oscillator or amplifier. In the study, results of an analysis of the general integral relations were applied in the case of an optically nonlinear, frequency-dispersive crystal in which SPDC produces collinear photons. Equations were found for the crystal orientation and pump wavelength, specific for each parametric-down-converting crystal, that eliminate the relative frequency dispersion of collinear degenerate (equal-frequency) signal and idler components up to the fourth order in the frequency-detuning parameter

  1. High average power scaling of optical parametric amplification through cascaded difference-frequency generators

    DOEpatents

    Jovanovic, Igor; Comaskey, Brian J.

    2004-09-14

    A first pump pulse and a signal pulse are injected into a first optical parametric amplifier. This produces a first amplified signal pulse. At least one additional pump pulse and the first amplified signal pulse are injected into at least one additional optical parametric amplifier producing an increased power coherent optical pulse.

  2. Multi-Watt femtosecond optical parametric master oscillator power amplifier at 43 MHz.

    PubMed

    Mörz, Florian; Steinle, Tobias; Steinmann, Andy; Giessen, Harald

    2015-09-07

    We present a high repetition rate mid-infrared optical parametric master oscillator power amplifier (MOPA) scheme, which is tunable from 1370 to 4120nm. Up to 4.3W average output power are generated at 1370nm, corresponding to a photon conversion efficiency of 78%. Bandwidths of 6 to 12nm with pulse durations between 250 and 400fs have been measured. Strong conversion saturation over the whole signal range is observed, resulting in excellent power stability. The system consists of a fiber-feedback optical parametric oscillator that seeds an optical parametric power amplifier. Both systems are pumped by the same Yb:KGW femtosecond oscillator.

  3. Temporal-contrast measurements of a white-light-seeded noncollinear optical parametric amplifier

    DOE PAGES

    Bromage, J.; Dorrer, C.; Zuegel, J. D.

    2015-09-01

    Ultra-intense optical parametric chirped-pulse systems require front ends with broad bandwidth and high temporal contrast. Temporal cross-correlation measurements of a white-light–seeded noncollinear optical parametric amplifier (NOPA) show that its prepulse contrast exceeds the 120 dB dynamic range of the broadband NOPA-based cross-correlator.

  4. High-gain mid-infrared optical-parametric generation pumped by microchip laser.

    PubMed

    Ishizuki, Hideki; Taira, Takunori

    2016-01-25

    High-gain mid-infrared optical-parametric generation was demonstrated by simple single-pass configuration using PPMgLN devices pumped by giant-pulse microchip laser. Effective mid-infrared wavelength conversion with 1 mJ output energy from 2.4 mJ pumping using conventional PPMgLN could be realized. Broadband optical-parametric generation from 1.7 to 2.6 µm could be also measured using chirped PPMgLN.

  5. Parametric Covariance Model for Horizon-Based Optical Navigation

    NASA Technical Reports Server (NTRS)

    Hikes, Jacob; Liounis, Andrew J.; Christian, John A.

    2016-01-01

    This Note presents an entirely parametric version of the covariance for horizon-based optical navigation measurements. The covariance can be written as a function of only the spacecraft position, two sensor design parameters, the illumination direction, the size of the observed planet, the size of the lit arc to be used, and the total number of observed horizon points. As a result, one may now more clearly understand the sensitivity of horizon-based optical navigation performance as a function of these key design parameters, which is insight that was obscured in previous (and nonparametric) versions of the covariance. Finally, the new parametric covariance is shown to agree with both the nonparametric analytic covariance and results from a Monte Carlo analysis.

  6. Image-rotating, 4-mirror, ring optical parametric oscillator

    DOEpatents

    Smith, Arlee V.; Armstrong, Darrell J.

    2004-08-10

    A device for optical parametric amplification utilizing four mirrors oriented in a nonplanar configuration where the optical plane formed by two of the mirrors is orthogonal to the optical plane formed by the other two mirrors and with the ratio of lengths of the laser beam paths approximately constant regardless of the scale of the device. With a cavity length of less than approximately 110 mm, a conversion efficiency of greater than 45% can be achieved.

  7. Implementing quantum optics with parametrically driven superconducting circuits

    NASA Astrophysics Data System (ADS)

    Aumentado, Jose

    Parametric coupling has received much attention, in part because it forms the core of many low-noise amplifiers in superconducting quantum information experiments. However, parametric coupling in superconducting circuits is, as a general rule, simple to generate and forms the basis of a methodology for interacting microwave fields at different frequencies. In the quantum regime, this has important consequences, allowing relative novices to do experiments in superconducting circuits today that were previously heroic efforts in quantum optics and cavity-QED. In this talk, I'll give an overview of some of our work demonstrating parametric coupling within the context of circuit-QED as well as some of the possibilities this concept creates in our field.

  8. Frequency domain optical parametric amplification

    PubMed Central

    Schmidt, Bruno E.; Thiré, Nicolas; Boivin, Maxime; Laramée, Antoine; Poitras, François; Lebrun, Guy; Ozaki, Tsuneyuki; Ibrahim, Heide; Légaré, François

    2014-01-01

    Today’s ultrafast lasers operate at the physical limits of optical materials to reach extreme performances. Amplification of single-cycle laser pulses with their corresponding octave-spanning spectra still remains a formidable challenge since the universal dilemma of gain narrowing sets limits for both real level pumped amplifiers as well as parametric amplifiers. We demonstrate that employing parametric amplification in the frequency domain rather than in time domain opens up new design opportunities for ultrafast laser science, with the potential to generate single-cycle multi-terawatt pulses. Fundamental restrictions arising from phase mismatch and damage threshold of nonlinear laser crystals are not only circumvented but also exploited to produce a synergy between increased seed spectrum and increased pump energy. This concept was successfully demonstrated by generating carrier envelope phase stable, 1.43 mJ two-cycle pulses at 1.8 μm wavelength. PMID:24805968

  9. Continuous-wave optical parametric oscillators on their way to the terahertz range

    NASA Astrophysics Data System (ADS)

    Sowade, Rosita; Breunig, Ingo; Kiessling, Jens; Buse, Karsten

    2010-02-01

    Continuous-wave optical parametric oscillators (OPOs) are known to be working horses for spectroscopy in the near- and mid-infrared. However, strong absorption in nonlinear media like lithium niobate complicates the generation of far-infrared light. This absorption leads to pump thresholds vastly exceeding the power of standard pump lasers. Our first approach was, therefore, to combine the established technique of photomixing with optical parametric oscillators. Here, two OPOs provide one wave each, with a tunable difference frequency. These waves are combined to a beat signal as a source for photomixers. Terahertz radiation between 0.065 and 1.018 THz is generated with powers in the order of nanowatts. To overcome the upper frequency limit of the opto-electronic photomixers, terahertz generation has to rely entirely on optical methods. Our all-optical approach, getting around the high thresholds for terahertz generation, is based on cascaded nonlinear processes: the resonantly enhanced signal field, generated in the primary parametric process, is intense enough to act as the pump for a secondary process, creating idler waves with frequencies in the terahertz regime. The latter ones are monochromatic and tunable with detected powers of more than 2 μW at 1.35 THz. Thus, continuous-wave optical parametric oscillators have entered the field of terahertz photonics.

  10. Wavelength-agile near-IR optical parametric oscillator using a deposited silicon waveguide.

    PubMed

    Wang, Ke-Yao; Foster, Mark A; Foster, Amy C

    2015-06-15

    Using a deposited hydrogenated amorphous silicon (a-Si:H) waveguide, we demonstrate ultra-broad bandwidth (60 THz) parametric amplification via four-wave mixing (FWM), and subsequently achieve the first silicon optical parametric oscillator (OPO) at near-IR wavelengths. Utilization of the time-dispersion-tuned technique provides an optical source with active wavelength tuning over 42 THz with a fixed pump wave.

  11. Comparing an optical parametric oscillator (OPO) as a viable alternative for mid-infrared tissue ablation with a free electron laser (FEL).

    PubMed

    Mackanos, Mark A; Simanovskii, Dmitrii M; Contag, Christopher H; Kozub, John A; Jansen, E Duco

    2012-11-01

    Beneficial medical laser ablation removes material efficiently with minimal collateral damage. A Mark-III free electron laser (FEL), at a wavelength of 6.45 μm has demonstrated minimal damage and high ablation yield in ocular and neural tissues. While this wavelength has shown promise for surgical applications, further advances are limited by the high overhead for FEL use. Alternative mid-infrared sources are needed for further development. We compared the FEL with a 5-μs pulse duration with a Q-switched ZGP-OPO with a 100-ns pulse duration at mid-infrared wavelengths. There were no differences in the ablation threshold of water and mouse dermis with these two sources in spite of the difference in their pulse structures. There was a significant difference in crater depth between the ZGP:OPO and the FEL. At 6.1 μm, the OPO craters are eight times the depth of the FEL craters. The OPO craters at 6.45 and 6.73 μm were six and five times the depth of the FEL craters, respectively. Bright-field (pump-probe) images showed the classic ablation mechanism from formation of a plume through collapse and recoil. The crater formation, ejection, and collapse phases occurred on a faster time-scale with the OPO than with the FEL. This research showed that a ZGP-OPO laser could be a viable alternative to FEL for clinical applications.

  12. Frequency comb generation in a continuously pumped optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Mosca, S.; Parisi, M.; Ricciardi, I.; Leo, F.; Hansson, T.; Erkintalo, M.; Maddaloni, P.; De Natale, P.; Wabnitz, S.; De Rosa, M.

    2018-02-01

    We demonstrate optical frequency comb generation in a continuously pumped optical parametric oscillator, in the parametric region around half of the pump frequency. We also model the dynamics of such quadratic combs using a single time-domain mean-field equation, and obtain simulation results that are in good agreement with experimentally observed spectra. Moreover, we numerically investigate the coherence properties of simulated combs, showing the existence of correlated and phase-locked combs. Our work could pave the way for a new class of frequency comb sources, which may enable straightforward access to new spectral regions and stimulate novel applications of frequency combs.

  13. Optical parametric osicllators with improved beam quality

    DOEpatents

    Smith, Arlee V.; Alford, William J.

    2003-11-11

    An optical parametric oscillator (OPO) having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

  14. Inverse four-wave-mixing and self-parametric amplification effect in optical fibre

    PubMed Central

    Turitsyn, Sergei K.; Bednyakova, Anastasia E.; Fedoruk, Mikhail P.; Papernyi, Serguei B.; Clements, Wallace R.L.

    2015-01-01

    An important group of nonlinear processes in optical fibre involves the mixing of four waves due to the intensity dependence of the refractive index. It is customary to distinguish between nonlinear effects that require external/pumping waves (cross-phase modulation and parametric processes such as four-wave mixing) and self-action of the propagating optical field (self-phase modulation and modulation instability). Here, we present a new nonlinear self-action effect, self-parametric amplification (SPA), which manifests itself as optical spectrum narrowing in normal dispersion fibre, leading to very stable propagation with a distinctive spectral distribution. The narrowing results from an inverse four-wave mixing, resembling an effective parametric amplification of the central part of the spectrum by energy transfer from the spectral tails. SPA and the observed stable nonlinear spectral propagation with random temporal waveform can find applications in optical communications and high power fibre lasers with nonlinear intra-cavity dynamics. PMID:26345290

  15. High repetition frequency PPMgOLN mid-infrared optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Liu, J.; Liu, Q.; Yan, X.; Chen, H.; Gong, M.

    2010-09-01

    A mid-infrared optical parametric oscillator (OPO) with the idler wavelengths of 3591 nm, 3384 nm, and 3164 nm at the repetition of 76.8 kHz is reported, and a high repetition frequency acousto-optic Q-switched Nd:YVO4 laser is used as the pump source. The OPO is designed as an external non-colinear single-resonator optical parametric oscillator. When the power of the pump light is 25.1 W, the idler with the wavelength of 3164 nm and the power of 4.3 W is generated. The corresponding signal light is 1603 nm with the power of 3.1 W. The efficiency from 1064 nm to 3160 nm can reach as high as 17.1%, and the efficiency of the OPO is 29.5%.

  16. Pulse compression in a synchronously pumped optical parametric oscillator from group-velocity mismatch.

    PubMed

    Khaydarov, J D; Andrews, J H; Singer, K D

    1994-06-01

    We report on experimental intracavity compression of generated pulses (down to one quarter of the pumppulse duration) in a widely tunable synchronously pumped picosecond optical parametric oscillator. This pulse compression takes place when the optical parametric oscillator is well above threshold and is due to the pronounced group-velocity mismatch of the pump and oscillating waves in the nonlinear crystal.

  17. Optical Parametric Amplification of Single Photon: Statistical Properties and Quantum Interference

    NASA Astrophysics Data System (ADS)

    Xu, Xue-Xiang; Yuan, Hong-Chun

    2014-05-01

    By using phase space method, we theoretically investigate the quantum statistical properties and quantum interference of optical parametric amplification of single photon. The statistical properties, such as the Wigner function (WF), average photon number, photon number distribution and parity, are derived analytically for the fields of the two output ports. The results indicate that the fields in the output ports are multiphoton states rather than single photon state due to the amplification of the optical parametric amplifiers (OPA). In addition, the phase sensitivity is also examined by using the detection scheme of parity measurement.

  18. Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion

    NASA Astrophysics Data System (ADS)

    Cho, Minhaeng

    2018-05-01

    Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

  19. Quantum optical measurement with tripartite entangled photons generated by triple parametric down-conversion.

    PubMed

    Cho, Minhaeng

    2018-05-14

    Parametric down-conversion is a second-order nonlinear optical process annihilating a pump photon and creating a pair of photons in the signal and idler modes. Then, by using two parametric down-converters and introducing a path indistinguishability for the two generated idler modes, a quantum coherence between two conjugate signal beams can be induced. Such a double spontaneous or stimulated parametric down-conversion scheme has been used to demonstrate quantum spectroscopy and imaging with undetected idler photons via measuring one-photon interference between their correlated signal beams. Recently, we considered another quantum optical measurement scheme utilizing W-type tripartite entangled signal photons that can be generated by employing three spontaneous parametric down-conversion crystals and by inducing coherences or path-indistinguishabilities between their correlated idler beams and between quantum vacuum fields. Here, we consider an extended triple stimulated parametric down-conversion scheme for quantum optical measurement of sample properties with undetected idler and photons. Noting the real effect of vacuum field indistinguishability on the fringe visibility as well as the role of zero-point field energy in the interferometry, we show that this scheme is an ideal and efficient way to create a coherent state of W-type entangled signal photons. We anticipate that this scheme would be of critical use in further developing quantum optical measurements in spectroscopy and microscopy with undetected photons.

  20. Fiber optical parametric amplifiers in optical communication systems

    PubMed Central

    Marhic (†), Michel E; Andrekson, Peter A; Petropoulos, Periklis; Radic, Stojan; Peucheret, Christophe; Jazayerifar, Mahmoud

    2015-01-01

    The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time-division multiplexed formats. High-quality mid-span spectral inversion has been demonstrated at 0.64 Tb/s, avoiding electronic dispersion compensation. All-optical amplitude regeneration of amplitude-modulated signals has been performed, while PSAs have been used to demonstrate phase regeneration of phase-modulated signals. A PSA with 1.1-dB noise figure has been demonstrated, and preliminary wavelength-division multiplexing experiments have been performed with PSAs. 512 Gb/s have been transmitted over 6,000 km by periodic phase conjugation. Simulations indicate that PIAs could reach data rate x reach products in excess of 14,000 Tb/s × km in realistic wavelength-division multiplexed long-haul networks. Technical challenges remaining to be addressed in order for fiber OPAs to become useful for long-haul communication networks are discussed. PMID:25866588

  1. Phase-sensitive fiber-based parametric all-optical switch.

    PubMed

    Parra-Cetina, Josué; Kumpera, Aleš; Karlsson, Magnus; Andrekson, Peter A

    2015-12-28

    We experimentally demonstrate, for the first time, an all-optical switch in a phase-sensitive fiber optic parametric amplifier operated in saturation. We study the effect of phase variation of the signal and idler waves on the pump power depletion. By changing the phase of a 0.9 mW signal/idler pair wave by π/2 rad, a pump power extinction ratio of 30.4 dB is achieved. Static and dynamic characterizations are also performed and time domain results presented.

  2. Beam splitter coupled CDSE optical parametric oscillator

    DOEpatents

    Levinos, Nicholas J.; Arnold, George P.

    1980-01-01

    An optical parametric oscillator is disclosed in which the resonant radiation is separated from the pump and output radiation so that it can be manipulated without interfering with them. Thus, for example, very narrow band output may readily be achieved by passing the resonant radiation through a line narrowing device which does not in itself interfere with either the pump radiation or the output radiation.

  3. Sensitivity enhancement in swept-source optical coherence tomography by parametric balanced detector and amplifier

    PubMed Central

    Kang, Jiqiang; Wei, Xiaoming; Li, Bowen; Wang, Xie; Yu, Luoqin; Tan, Sisi; Jinata, Chandra; Wong, Kenneth K. Y.

    2016-01-01

    We proposed a sensitivity enhancement method of the interference-based signal detection approach and applied it on a swept-source optical coherence tomography (SS-OCT) system through all-fiber optical parametric amplifier (FOPA) and parametric balanced detector (BD). The parametric BD was realized by combining the signal and phase conjugated idler band that was newly-generated through FOPA, and specifically by superimposing these two bands at a photodetector. The sensitivity enhancement by FOPA and parametric BD in SS-OCT were demonstrated experimentally. The results show that SS-OCT with FOPA and SS-OCT with parametric BD can provide more than 9 dB and 12 dB sensitivity improvement, respectively, when compared with the conventional SS-OCT in a spectral bandwidth spanning over 76 nm. To further verify and elaborate their sensitivity enhancement, a bio-sample imaging experiment was conducted on loach eyes by conventional SS-OCT setup, SS-OCT with FOPA and parametric BD at different illumination power levels. All these results proved that using FOPA and parametric BD could improve the sensitivity significantly in SS-OCT systems. PMID:27446655

  4. Method to improve optical parametric oscillator beam quality

    DOEpatents

    Smith, Arlee V.; Alford, William J.; Bowers, Mark S.

    2003-11-11

    A method to improving optical parametric oscillator (OPO) beam quality having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

  5. Simultaneous parametric generation and up-conversion of entangled optical images

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Saygin, M. Yu., E-mail: mihasyu@gmail.com; Chirkin, A. S., E-mail: aschirkin@rambler.r

    A quantum theory of parametric amplification and frequency conversion of an optical image in coupled nonlinear optical processes that include one parametric amplification process at high-frequency pumping and two up-conversion processes in the same pump field is developed. The field momentum operator that takes into account the diffraction and group velocities of the waves is used to derive the quantum equations related to the spatial dynamics of the images during the interaction. An optical scheme for the amplification and conversion of a close image is considered. The mean photon number density and signal-to-noise ratio are calculated in the fixed-pump-field approximationmore » for images at various frequencies. It has been established that the signal-to-noise ratio decreases with increasing interaction length in the amplified image and increases in the images at the generated frequencies, tending to asymptotic values for all interacting waves. The variance of the difference of the numbers of photons is calculated for various pairs of frequencies. The quantum entanglement of the optical images formed in a high-frequency pump field is shown to be converted to higher frequencies during the generation of sum frequencies. Thus, two pairs of entangled optical images are produced in the process considered.« less

  6. Ultra-broadband tunable (0.67-2.57 µm) optical vortex parametric oscillator

    NASA Astrophysics Data System (ADS)

    Araki, Shungo; Suzuki, Kensuke; Nishida, Shigeki; Mamuti, Roukuya; Miyamoto, Katsuhiko; Omatsu, Takashige

    2017-10-01

    We demonstrate an ultra-broadband (>2-octave band) tunable optical vortex laser comprising an optical-vortex-pumped optical parametric oscillator by employing a nanosecond pulse (˜10 ns) green laser and cascaded non-critical phase-matching LiB3O5 crystals (45 mm long each). With this system, an optical vortex output was produced over an extremely wide wavelength range of 0.67-2.57 µm.

  7. Cooling optically levitated dielectric nanoparticles via parametric feedback

    NASA Astrophysics Data System (ADS)

    Neukirch, Levi; Rodenburg, Brandon; Bhattacharya, Mishkatul; Vamivakas, Nick

    2015-05-01

    The inability to leverage resonant scattering processes involving internal degrees of freedom differentiates optical cooling experiments performed with levitated dielectric nanoparticles, from similar atomic and molecular traps. Trapping in optical cavities or the application of active feedback techniques have proven to be effective ways to circumvent this limitation. We present our nanoparticle optical cooling apparatus, which is based on parametric feedback modulation of a single-beam gradient force optical trap. This scheme allows us to achieve effective center-of-mass temperatures well below 1 kelvin for our ~ 1 ×10-18 kg particles, at modest vacuum pressures. The method provides a versatile platform, with parameter tunability not found in conventional tethered nanomechanical systems. Potential applications include investigations of nonequilibrium nanoscale thermodynamics, ultra-sensitive force metrology, and mesoscale quantum mechanics and hybrid systems. Supported by the office of Naval Research award number N000141410442.

  8. Experimental demonstration of spatially coherent beam combining using optical parametric amplification.

    PubMed

    Kurita, Takashi; Sueda, Keiichi; Tsubakimoto, Koji; Miyanaga, Noriaki

    2010-07-05

    We experimentally demonstrated coherent beam combining using optical parametric amplification with a nonlinear crystal pumped by random-phased multiple-beam array of the second harmonic of a Nd:YAG laser at 10-Hz repetition rate. In the proof-of-principle experiment, the phase jump between two pump beams was precisely controlled by a motorized actuator. For the demonstration of multiple-beam combining a random phase plate was used to create random-phased beamlets as a pump pulse. Far-field patterns of the pump, the signal, and the idler indicated that the spatially coherent signal beams were obtained on both cases. This approach allows scaling of the intensity of optical parametric chirped pulse amplification up to the exa-watt level while maintaining diffraction-limited beam quality.

  9. Continuous parametric feedback cooling of a single atom in an optical cavity

    NASA Astrophysics Data System (ADS)

    Sames, C.; Hamsen, C.; Chibani, H.; Altin, P. A.; Wilk, T.; Rempe, G.

    2018-05-01

    We demonstrate a feedback algorithm to cool a single neutral atom trapped inside a standing-wave optical cavity. The algorithm is based on parametric modulation of the confining potential at twice the natural oscillation frequency of the atom, in combination with fast and repetitive atomic position measurements. The latter serve to continuously adjust the modulation phase to a value for which parametric excitation of the atomic motion is avoided. Cooling is limited by the measurement backaction which decoheres the atomic motion after only a few oscillations. Nonetheless, applying this feedback scheme to an ˜5 -kHz oscillation mode increases the average storage time of a single atom in the cavity by a factor of 60 to more than 2 s. In contrast to previous feedback schemes, our algorithm is also capable of cooling a much faster ˜500 -kHz oscillation mode within just microseconds. This demonstrates that parametric cooling is a powerful technique that can be applied in all experiments where optical access is limited.

  10. Optical parametric amplification of arbitrarily polarized light in periodically poled LiNbO3.

    PubMed

    Shao, Guang-hao; Song, Xiao-shi; Xu, Fei; Lu, Yan-qing

    2012-08-13

    Optical parametric amplification (OPA) of arbitrarily polarized light is proposed in a multi-section periodically poled Lithium Niobate (PPLN). External electric field is applied on selected sections to induce the polarization rotation of involved lights, thus the quasi-phase matched optical parametric processes exhibit polarization insensitivity under suitable voltage. In addition to the amplified signal wave, an idler wave with the same polarization is generated simultaneously. As an example, a ~10 times OPA showing polarization independency is simulated. Applications of this technology are also discussed.

  11. Stable integrated hyper-parametric oscillator based on coupled optical microcavities.

    PubMed

    Armaroli, Andrea; Feron, Patrice; Dumeige, Yannick

    2015-12-01

    We propose a flexible scheme based on three coupled optical microcavities that permits us to achieve stable oscillations in the microwave range, the frequency of which depends only on the cavity coupling rates. We find that the different dynamical regimes (soft and hard excitation) affect the oscillation intensity, but not their periods. This configuration may permit us to implement compact hyper-parametric sources on an integrated optical circuit with interesting applications in communications, sensing, and metrology.

  12. Phase mismatched optical parametric generation in semiconductor magnetoplasma

    NASA Astrophysics Data System (ADS)

    Dubey, Swati; Ghosh, S.; Jain, Kamal

    2017-05-01

    Optical parametric generation involves the interaction of pump, signal, and idler waves satisfying law of conservation of energy. Phase mismatch parameter plays important role for the spatial distribution of the field along the medium. In this paper instead of exactly matching wave vector, a small mismatch is admitted with a degree of phase velocity mismatch between these waves. Hence the medium must possess certain finite coherence length. This wave mixing process is well explained by coupled mode theory and one dimensional hydrodynamic model. Based on this scheme, expressions for threshold pump field and transmitted intensity have been derived. It is observed that the threshold pump intensity and transmitted intensity can be manipulated by varying doping concentration and magnetic field under phase mismatched condition. A compound semiconductor crystal of n-InSb is assumed to be shined at 77 K by a 10.6μm CO2 laser with photon energy well below band gap energy of the crystal, so that only free charge carrier influence the optical properties of the medium for the I.R. parametric generation in a semiconductor plasma medium. Favorable parameters were explored to incite the said process keeping in mind the cost effectiveness and conversion efficiency of the process.

  13. Ultrafast Airy beam optical parametric oscillator

    PubMed Central

    Apurv Chaitanya, N.; Kumar, S. Chaitanya; Aadhi, A.; Samanta, G. K.; Ebrahim-Zadeh, M.

    2016-01-01

    We report on the first realization of an ultrafast Airy beam optical parametric oscillator (OPO). By introducing intracavity cubic phase modulation to the resonant Gaussian signal in a synchronously-pumped singly-resonant OPO cavity and its subsequent Fourier transformation, we have generated 2-dimensional Airy beam in the output signal across a 250 nm tuning range in the near-infrared. The generated Airy beam can be tuned continuously from 1477 to 1727 nm, providing an average power of as much as 306 mW at 1632 nm in pulses of ~23 ps duration with a spectral bandwidth of 1.7 nm. PMID:27476910

  14. An Optical Parametric Amplifier for Profiling Gases of Atmospheric Interest

    NASA Technical Reports Server (NTRS)

    Heaps, William (Technical Monitor); Burris, John; Richter, Dale

    2004-01-01

    This paper describes the development of a lidar transmitter using an optical parametric amplifier. It is designed for profiling gases of atmospheric interest at high spatial and temporal precision in the near-IR. Discussions on desirable characteristics for such a transmitter with specific reference to the case of CO, are made.

  15. Normal dispersion femtosecond fiber optical parametric oscillator.

    PubMed

    Nguyen, T N; Kieu, K; Maslov, A V; Miyawaki, M; Peyghambarian, N

    2013-09-15

    We propose and demonstrate a synchronously pumped fiber optical parametric oscillator (FOPO) operating in the normal dispersion regime. The FOPO generates chirped pulses at the output, allowing significant pulse energy scaling potential without pulse breaking. The output average power of the FOPO at 1600 nm was ∼60  mW (corresponding to 1.45 nJ pulse energy and ∼55% slope power conversion efficiency). The output pulses directly from the FOPO were highly chirped (∼3  ps duration), and they could be compressed outside of the cavity to 180 fs by using a standard optical fiber compressor. Detailed numerical simulation was also performed to understand the pulse evolution dynamics around the laser cavity. We believe that the proposed design concept is useful for scaling up the pulse energy in the FOPO using different pumping wavelengths.

  16. Order parameter description of walk-off effect on pattern selection in degenerate optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Taki, Majid; San Miguel, Maxi; Santagiustina, Marco

    2000-02-01

    Degenerate optical parametric oscillators can exhibit both uniformly translating fronts and nonuniformly translating envelope fronts under the walk-off effect. The nonlinear dynamics near threshold is shown to be described by a real convective Swift-Hohenberg equation, which provides the main characteristics of the walk-off effect on pattern selection. The predictions of the selected wave vector and the absolute instability threshold are in very good quantitative agreement with numerical solutions found from the equations describing the optical parametric oscillator.

  17. Aperture scaling effects with monolithic periodically poled lithium niobate optical parametric oscillators and generators.

    PubMed

    Missey, M; Dominic, V; Powers, P; Schepler, K L

    2000-02-15

    We used elliptical beams to demonstrate aperture scaling effects in nanosecond single-grating and multigrating periodically poled lithium niobate (PPLN) monolithic optical parametric oscillators and generators. Increasing the cavity Fresnel number in single-grating crystals broadened both the beam divergence and the spectral bandwidth. Both effects are explained in terms of the phase-matching geometry. These effects are suppressed when a multigrating PPLN crystal is used because the individual gratings provide small effective subapertures. A flood-pumped multigrating optical parametric generator displayed a low output beam divergence and contained 19 pairs of signal and idler frequencies.

  18. Experimental realization of a feedback optical parametric amplifier with four-wave mixing

    NASA Astrophysics Data System (ADS)

    Pan, Xiaozhou; Chen, Hui; Wei, Tianxiang; Zhang, Jun; Marino, Alberto M.; Treps, Nicolas; Glasser, Ryan T.; Jing, Jietai

    2018-04-01

    Optical parametric amplifiers (OPAs) play a fundamental role in the generation of quantum correlation for quantum information processing and quantum metrology. In order to increase the communication fidelity of the quantum information protocol and the measurement precision of quantum metrology, it requires a high degree of quantum correlation. In this Rapid Communication we report a feedback optical parametric amplifier that employs a four-wave mixing (FWM) process as the underlying OPA and a beam splitter as the feedback controller. We first construct a theoretical model for this feedback-based FWM process and experimentally study the effect of the feedback control on the quantum properties of the system. Specifically, we find that the quantum correlation between the output fields can be enhanced by tuning the strength of the feedback.

  19. Competing collinear and noncollinear interactions in chirped quasi-phase-matched optical parametric amplifiers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, M. M.

    Chirped quasi-phase-matched optical parametric amplifiers (chirped QPM OPAs) are investigated experimentally. The measured collinear gain is constant over a broad bandwidth, which makes these devices attractive candidates for use in femtosecond amplifier systems. The experiment also shows that chirped QPM OPAs support noncollinear gain-guided modes. These modes can dominate the desired collinear gain and generate intense parametric fluorescence. Finally, design guidelines to mitigate these parasitic processes are discussed.

  20. Regularized linearization for quantum nonlinear optical cavities: application to degenerate optical parametric oscillators.

    PubMed

    Navarrete-Benlloch, Carlos; Roldán, Eugenio; Chang, Yue; Shi, Tao

    2014-10-06

    Nonlinear optical cavities are crucial both in classical and quantum optics; in particular, nowadays optical parametric oscillators are one of the most versatile and tunable sources of coherent light, as well as the sources of the highest quality quantum-correlated light in the continuous variable regime. Being nonlinear systems, they can be driven through critical points in which a solution ceases to exist in favour of a new one, and it is close to these points where quantum correlations are the strongest. The simplest description of such systems consists in writing the quantum fields as the classical part plus some quantum fluctuations, linearizing then the dynamical equations with respect to the latter; however, such an approach breaks down close to critical points, where it provides unphysical predictions such as infinite photon numbers. On the other hand, techniques going beyond the simple linear description become too complicated especially regarding the evaluation of two-time correlators, which are of major importance to compute observables outside the cavity. In this article we provide a regularized linear description of nonlinear cavities, that is, a linearization procedure yielding physical results, taking the degenerate optical parametric oscillator as the guiding example. The method, which we call self-consistent linearization, is shown to be equivalent to a general Gaussian ansatz for the state of the system, and we compare its predictions with those obtained with available exact (or quasi-exact) methods. Apart from its operational value, we believe that our work is valuable also from a fundamental point of view, especially in connection to the question of how far linearized or Gaussian theories can be pushed to describe nonlinear dissipative systems which have access to non-Gaussian states.

  1. Phase matched parametric amplification via four-wave mixing in optical microfibers.

    PubMed

    Abdul Khudus, Muhammad I M; De Lucia, Francesco; Corbari, Costantino; Lee, Timothy; Horak, Peter; Sazio, Pier; Brambilla, Gilberto

    2016-02-15

    Four-wave mixing (FWM) based parametric amplification in optical microfibers (OMFs) is demonstrated over a wavelength range of over 1000 nm by exploiting their tailorable dispersion characteristics to achieve phase matching. Simulations indicate that for any set of wavelengths satisfying the FWM energy conservation condition there are two diameters at which phase matching in the fundamental mode can occur. Experiments with a high-power pulsed source working in conjunction with a periodically poled silica fiber (PPSF), producing both fundamental and second harmonic signals, are undertaken to investigate the possibility of FWM parametric amplification in OMFs. Large increases of idler output power at the third harmonic wavelength were recorded for diameters close to the two phase matching diameters. A total amplification of more than 25 dB from the initial signal was observed in a 6 mm long optical microfiber, after accounting for the thermal drift of the PPSF and other losses in the system.

  2. Intermodal Parametric Frequency Conversion in Optical Fibers

    NASA Astrophysics Data System (ADS)

    Demas, Jeffrey D.

    Lasers are an essential technology enabling countless fields of optics, however, their operation wavelengths are limited to isolated regions across the optical spectrum due to the need for suitable gain media. Parametric frequency conversion (PFC) is an attractive means to convert existing lasers to new colors using nonlinear optical interactions rather than the material properties of the host medium, allowing for the development of high power laser sources across the entire optical spectrum. PFC in bulk chi(2) crystals has led to the development of the optical parametric oscillator, which is currently the standard source for high power light at non-traditional wavelengths in the laboratory setting. Ideally, however, one could implement PFC in an optical fiber, thus leveraging the crucial benefits of a guided-wave geometry: alignment-free, compact, and robust operation. Four-wave mixing (FWM) is a nonlinear effect in optical fibers that can be used to convert frequencies, the major challenge being conservation of momentum, or phase matching, between the interacting light waves. Phase matching can be satisfied through the interaction of different spatial modes in a multi-mode fiber, however, previous demonstrations have been limited by mode stability and narrow-band FWM gain. Alternatively, phase matching within the fundamental mode can be realized in high-confinement waveguides (such as photonic crystal fibers), but achieving the anomalous waveguide dispersion necessary for phase matching at pump wavelengths near ˜1 mum (where the highest power fiber lasers emit) comes at the cost of reducing the effective area of the mode, thus limiting power-handling. Here, we specifically consider the class of Bessel-like LP0,m modes in step-index fibers. It has been shown that these modes can be selectively excited and guided stably for long lengths of fiber, and mode stability increases with mode order 'm'. The effective area of modes in these fibers can be very large (>6000

  3. 2.5 TW, two-cycle IR laser pulses via frequency domain optical parametric amplification.

    PubMed

    Gruson, V; Ernotte, G; Lassonde, P; Laramée, A; Bionta, M R; Chaker, M; Di Mauro, L; Corkum, P B; Ibrahim, H; Schmidt, B E; Legaré, F

    2017-10-30

    Broadband optical parametric amplification in the IR region has reached a new milestone through the use of a non-collinear Frequency domain Optical Parametric Amplification system. We report a laser source delivering 11.6 fs pulses with 30 mJ of energy at a central wavelength of 1.8 μm at 10 Hz repetition rate corresponding to a peak power of 2.5 TW. The peak power scaling is accompanied by a pulse shortening of about 20% upon amplification due to the spectral reshaping with higher gain in the spectral wings. This source paves the way for high flux soft X-ray pulses and IR-driven laser wakefield acceleration.

  4. Carrier-phase control among subharmonic pulses in a femtosecond optical parametric oscillator.

    PubMed

    Kobayashi, Y; Torizuka, K

    2001-08-15

    We have generated femtosecond subharmonic pulses by using an optical parametric oscillator. The optical frequencies of the idler and the signal are one third and two thirds, respectively, of the optical frequency of the pump pulse. The carrier phase of the signal pulse relative to that of the pump pulse was locked by electronic feedback. The carrier-envelope phase slip frequency of the signal pulse relative to that of the pump was locked to F/6 , where F is defined as the repetition frequency.

  5. Integrated modeling for parametric evaluation of smart x-ray optics

    NASA Astrophysics Data System (ADS)

    Dell'Agostino, S.; Riva, M.; Spiga, D.; Basso, S.; Civitani, Marta

    2014-08-01

    This work is developed in the framework of AXYOM project, which proposes to study the application of a system of piezoelectric actuators to grazing-incidence X-ray telescope optic prototypes: thin glass or plastic foils, in order to increase their angular resolution. An integrated optomechanical model has been set up to evaluate the performances of X-ray optics under deformation induced by Piezo Actuators. Parametric evaluation has been done looking at different number and position of actuators to optimize the outcome. Different evaluations have also been done over the actuator types, considering Flexible Piezoceramic, Multi Fiber Composites piezo actuators, and PVDF.

  6. Intensity and temporal noise characteristics in femtosecond optical parametric amplifiers.

    PubMed

    Chen, Wei; Fan, Jintao; Ge, Aichen; Song, Huanyu; Song, Youjian; Liu, Bowen; Chai, Lu; Wang, Chingyue; Hu, Minglie

    2017-12-11

    We characterize the relative intensity noise (RIN) and relative timing jitter (RTJ) between the signal and pump pulses of optical parametric amplifiers (OPAs) seeded by three different seed sources. Compared to a white-light continuum (WLC) seeded- and an optical parametric generator (OPG) seeded OPA, the narrowband CW seeded OPA exhibits the lowest root-mean-square (RMS) RIN and RTJ of 0.79% and 0.32 fs, respectively, integrated from 1 kHz to the Nyquist frequency of 1.25 MHz. An improved numerical model based on a forward Maxwell equation (FME) is built to investigate the transfers of the pump and seed's noise to the resulting OPAs' intensity and temporal fluctuation. Both the experimental and numerical study indicate that the low level of noise from the narrowband CW seeded OPA is attributed to the elimination of the RIN and RTJ coupled from the noise of seed source, being one of the important contributions to RIN and timing jitter in the other two OPAs. The approach to achieve lower level of noise from this CW seeded OPA by driving it close to saturation is also discussed with the same numerical model.

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

    PubMed

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

    2013-03-01

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

  8. Complementary optical rogue waves in parametric three-wave mixing.

    PubMed

    Chen, Shihua; Cai, Xian-Ming; Grelu, Philippe; Soto-Crespo, J M; Wabnitz, Stefan; Baronio, Fabio

    2016-03-21

    We investigate the resonant interaction of two optical pulses of the same group velocity with a pump pulse of different velocity in a weakly dispersive quadratic medium and report on the complementary rogue wave dynamics which are unique to such a parametric three-wave mixing. Analytic rogue wave solutions up to the second order are explicitly presented and their robustness is confirmed by numerical simulations, in spite of the onset of modulation instability activated by quantum noise.

  9. Long-range parametric amplification of THz wave with absorption loss exceeding parametric gain.

    PubMed

    Wang, Tsong-Dong; Huang, Yen-Chieh; Chuang, Ming-Yun; Lin, Yen-Hou; Lee, Ching-Han; Lin, Yen-Yin; Lin, Fan-Yi; Kitaeva, Galiya Kh

    2013-01-28

    Optical parametric mixing is a popular scheme to generate an idler wave at THz frequencies, although the THz wave is often absorbing in the nonlinear optical material. It is widely suggested that the useful material length for co-directional parametric mixing with strong THz-wave absorption is comparable to the THz-wave absorption length in the material. Here we show that, even in the limit of the absorption loss exceeding parametric gain, the THz idler wave can grows monotonically from optical parametric amplification over a much longer distance in a nonlinear optical material until pump depletion. The coherent production of the non-absorbing signal wave can assist the growth of the highly absorbing idler wave. We also show that, for the case of an equal input pump and signal in difference frequency generation, the quick saturation of the THz idler wave predicted from a much simplified and yet popular plane-wave model fails when fast diffraction of the THz wave from the co-propagating optical mixing waves is considered.

  10. Experimental sub-Rayleigh resolution by an unseeded high-gain optical parametric amplifier for quantum lithography

    NASA Astrophysics Data System (ADS)

    Sciarrino, Fabio; Vitelli, Chiara; de Martini, Francesco; Glasser, Ryan; Cable, Hugo; Dowling, Jonathan P.

    2008-01-01

    Quantum lithography proposes to adopt entangled quantum states in order to increase resolution in interferometry. In the present paper we experimentally demonstrate that the output of a high-gain optical parametric amplifier can be intense yet exhibits quantum features, namely, sub-Rayleigh fringes, as proposed by [Agarwal , Phys. Rev. Lett. 86, 1389 (2001)]. We investigate multiphoton states generated by a high-gain optical parametric amplifier operating with a quantum vacuum input for gain values up to 2.5. The visibility has then been increased by means of three-photon absorption. The present paper opens interesting perspectives for the implementation of such an advanced interferometrical setup.

  11. Effect of idler absorption in pulsed optical parametric oscillators.

    PubMed

    Rustad, Gunnar; Arisholm, Gunnar; Farsund, Øystein

    2011-01-31

    Absorption at the idler wavelength in an optical parametric oscillator (OPO) is often considered detrimental. We show through simulations that pulsed OPOs with significant idler absorption can perform better than OPOs with low idler absorption both in terms of conversion efficiency and beam quality. The main reason for this is reduced back conversion. We also show how the beam quality depends on the beam width and pump pulse length, and present scaling relations to use the example simulations for other pulsed nanosecond OPOs.

  12. Terahertz generation by difference frequency generation from a compact optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Li, Zhongyang; Wang, Silei; Wang, Mengtao; Wang, Weishu

    2017-11-01

    Terahertz (THz) generation by difference frequency generation (DFG) processes with dual idler waves is theoretically analyzed. The dual idler waves are generated by a compact optical parametric oscillator (OPO) with periodically poled lithium niobate (PPLN). The phase-matching conditions in a same PPLN for the optical parametric oscillation generating signal and idler waves and for the DFG generating THz waves can be simultaneously satisfied by selecting the poling period of PPLN. Moreover, 3-order cascaded DFG processes generating THz waves can be realized in the same PPLN. To take an example of 8.341 THz which locates in the vicinity of polariton resonances, THz intensities and quantum conversion efficiencies are calculated. Compared with non-cascaded DFG processes, THz intensities of 8.341 THz in 3-order cascaded DFG processes increase to 2.57 times. When the pump intensity equals to 20 MW/mm2, the quantum conversion efficiency of 106% in 3-order cascaded DFG processes can be realized, which exceeds the Manley-Rowe limit.

  13. Gain statistics of a fiber optical parametric amplifier with a temporally incoherent pump.

    PubMed

    Xu, Y Q; Murdoch, S G

    2010-03-15

    We present an investigation of the statistics of the gain fluctuations of a fiber optical parametric amplifier pumped with a temporally incoherent pump. We derive a simple expression for the probability distribution of the gain of the amplified optical signal. The gain statistics are shown to be a strong function of the signal detuning and allow the possibility of generating optical gain distributions with controllable long-tails. Very good agreement is found between this theory and the experimentally measured gain distributions of an incoherently pumped amplifier.

  14. Bifurcation analysis of eight coupled degenerate optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Ito, Daisuke; Ueta, Tetsushi; Aihara, Kazuyuki

    2018-06-01

    A degenerate optical parametric oscillator (DOPO) network realized as a coherent Ising machine can be used to solve combinatorial optimization problems. Both theoretical and experimental investigations into the performance of DOPO networks have been presented previously. However a problem remains, namely that the dynamics of the DOPO network itself can lower the search success rates of globally optimal solutions for Ising problems. This paper shows that the problem is caused by pitchfork bifurcations due to the symmetry structure of coupled DOPOs. Some two-parameter bifurcation diagrams of equilibrium points express the performance deterioration. It is shown that the emergence of non-ground states regarding local minima hampers the system from reaching the ground states corresponding to the global minimum. We then describe a parametric strategy for leading a system to the ground state by actively utilizing the bifurcation phenomena. By adjusting the parameters to break particular symmetry, we find appropriate parameter sets that allow the coherent Ising machine to obtain the globally optimal solution alone.

  15. Measurement of the photon statistics and the noise figure of a fiber-optic parametric amplifier.

    PubMed

    Voss, Paul L; Tang, Renyong; Kumar, Prem

    2003-04-01

    We report measurement of the noise statistics of spontaneous parametric fluorescence in a fiber parametric amplifier with single-mode, single-photon resolution. We employ optical homodyne tomography for this purpose, which also provides a self-calibrating measurement of the noise figure of the amplifier. The measured photon statistics agree with quantum-mechanical predictions, and the amplifier's noise figure is found to be almost quantum limited.

  16. Power scaling of supercontinuum seeded megahertz-repetition rate optical parametric chirped pulse amplifiers.

    PubMed

    Riedel, R; Stephanides, A; Prandolini, M J; Gronloh, B; Jungbluth, B; Mans, T; Tavella, F

    2014-03-15

    Optical parametric chirped-pulse amplifiers with high average power are possible with novel high-power Yb:YAG amplifiers with kW-level output powers. We demonstrate a compact wavelength-tunable sub-30-fs amplifier with 11.4 W average power with 20.7% pump-to-signal conversion efficiency. For parametric amplification, a beta-barium borate crystal is pumped by a 140 W, 1 ps Yb:YAG InnoSlab amplifier at 3.25 MHz repetition rate. The broadband seed is generated via supercontinuum generation in a YAG crystal.

  17. Numerical analysis of СО laser frequency conversion efficiency in BaGa2GeSe6 crystal

    NASA Astrophysics Data System (ADS)

    Ionin, A. A.; Kinyaevskiy, I. O.; Mozhaeva, V. A.

    2018-03-01

    Non-linear optical characteristics of a new BaGa2GeSe6 crystal were numerically studied and compared with ones of the well-known mid-IR nonlinear crystal ZnGeP2 (ZGP). The calculations demonstrated the new crystal to be more efficient or, at least, competitive with the ZGP crystal for frequency conversion of CO- and CO2-laser radiation. It was found that a broadband two-stage frequency conversion of multi-line CO-laser radiation in this crystal is possible within the 2.5-9.0 µm wavelength range, with higher efficiency than in the ZGP crystal.

  18. Efficient two-stage dual-beam noncollinear optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Cheng, Yu-Hsiang; Gao, Frank Y.; Poulin, Peter R.; Nelson, Keith A.

    2018-06-01

    We have constructed a noncollinear optical parametric amplifier with two signal beams amplified in the same nonlinear crystal. This dual-beam design is more energy-efficient than operating two amplifiers in parallel. The cross-talk between two beams has been characterized and discussed. We have also added a second amplification stage to enhance the output of one of the arms, which is then frequency-doubled for ultraviolet generation. This single device provides two tunable sources for ultrafast spectroscopy in the ultraviolet and visible region.

  19. Numerical investigations of non-collinear optical parametric chirped pulse amplification for Laguerre-Gaussian vortex beam

    NASA Astrophysics Data System (ADS)

    Xu, Lu; Yu, Lianghong; Liang, Xiaoyan

    2016-04-01

    We present for the first time a scheme to amplify a Laguerre-Gaussian vortex beam based on non-collinear optical parametric chirped pulse amplification (OPCPA). In addition, a three-dimensional numerical model of non-collinear optical parametric amplification was deduced in the frequency domain, in which the effects of non-collinear configuration, temporal and spatial walk-off, group-velocity dispersion and diffraction were also taken into account, to trace the dynamics of the Laguerre-Gaussian vortex beam and investigate its critical parameters in the non-collinear OPCPA process. Based on the numerical simulation results, the scheme shows promise for implementation in a relativistic twisted laser pulse system, which will diversify the light-matter interaction field.

  20. A fiber-laser-pumped four-wavelength continuous-wave mid-infrared optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Shang, Yaping; Li, Xiao; Xu, Xiaojun

    2017-10-01

    In this paper, a four-wavelength continuous-wave mid-infrared optical parametric oscillator was demonstrated for the first time. The pump source was a home-built linearly polarized Yb-doped fiber laser and the maximum output power was 72.5 W. The pump source had three central wavelengths locating at 1060 nm, 1065 nm and 1080 nm. Four idler emissions with different wavelengths were generated which were 3132 nm, 3171 nm, 3310 nm and 3349 nm under the maximum pump power. The maximum idler output reached 8.7 W, indicating a 15% pump-to-idler slope efficiency. The signal wave generated in the experiment had two wavelengths which were 1595 nm and 1603 nm under the maximum pump power. It was analyzed that four nonlinear progresses occurred in the experiment, two of them being optical parametric oscillation and the rest two being intracavity difference frequency generation.

  1. Ground and Airborne Methane Measurements with an Optical Parametric Amplifier

    NASA Technical Reports Server (NTRS)

    Numata, Kenji

    2012-01-01

    We report on ground and airborne atmospheric methane measurements with a differential absorption lidar using an optical parametric amplifier (OPA). Methane is a strong greenhouse gas on Earth and its accurate global mapping is urgently needed to understand climate change. We are developing a nanosecond-pulsed OPA for remote measurements of methane from an Earth-orbiting satellite. We have successfully demonstrated the detection of methane on the ground and from an airplane at approximately 11-km altitude.

  2. Mid-infrared optical parametric oscillator pumped by an amplified random fiber laser

    NASA Astrophysics Data System (ADS)

    Shang, Yaping; Shen, Meili; Wang, Peng; Li, Xiao; Xu, Xiaojun

    2017-01-01

    Recently, the concept of random fiber lasers has attracted a great deal of attention for its feature to generate incoherent light without a traditional laser resonator, which is free of mode competition and insure the stationary narrow-band continuous modeless spectrum. In this Letter, we reported the first, to the best of our knowledge, optical parametric oscillator (OPO) pumped by an amplified 1070 nm random fiber laser (RFL), in order to generate stationary mid-infrared (mid-IR) laser. The experiment realized a watt-level laser output in the mid-IR range and operated relatively stable. The use of the RFL seed source allowed us to take advantage of its respective stable time-domain characteristics. The beam profile, spectrum and time-domain properties of the signal light were measured to analyze the process of frequency down-conversion process under this new pumping condition. The results suggested that the near-infrared (near-IR) signal light `inherited' good beam performances from the pump light. Those would be benefit for further develop about optical parametric process based on different pumping circumstances.

  3. Noise-figure limit of fiber-optical parametric amplifiers and wavelength converters: experimental investigation

    NASA Astrophysics Data System (ADS)

    Tang, Renyong; Voss, Paul L.; Lasri, Jacob; Devgan, Preetpaul; Kumar, Prem

    2004-10-01

    Recent theoretical work predicts that the quantum-limited noise figure of a chi(3)-based fiber-optical parametric amplifier operating as a phase-insensitive in-line amplifier or as a wavelength converter exceeds the standard 3-dB limit at high gain. The degradation of the noise figure is caused by the excess noise added by the unavoidable Raman gain and loss occurring at the signal and the converted wavelengths. We present detailed experimental evidence in support of this theory through measurements of the gain and noise-figure spectra for phase-insensitive parametric amplification and wavelength conversion in a continuous-wave amplifier made from 4.4 km of dispersion-shifted fiber. The theory is also extended to include the effect of distributed linear loss on the noise figure of such a long-length parametric amplifier and wavelength converter.

  4. Quantum state engineering of light with continuous-wave optical parametric oscillators.

    PubMed

    Morin, Olivier; Liu, Jianli; Huang, Kun; Barbosa, Felippe; Fabre, Claude; Laurat, Julien

    2014-05-30

    Engineering non-classical states of the electromagnetic field is a central quest for quantum optics(1,2). Beyond their fundamental significance, such states are indeed the resources for implementing various protocols, ranging from enhanced metrology to quantum communication and computing. A variety of devices can be used to generate non-classical states, such as single emitters, light-matter interfaces or non-linear systems(3). We focus here on the use of a continuous-wave optical parametric oscillator(3,4). This system is based on a non-linear χ(2) crystal inserted inside an optical cavity and it is now well-known as a very efficient source of non-classical light, such as single-mode or two-mode squeezed vacuum depending on the crystal phase matching. Squeezed vacuum is a Gaussian state as its quadrature distributions follow a Gaussian statistics. However, it has been shown that number of protocols require non-Gaussian states(5). Generating directly such states is a difficult task and would require strong χ(3) non-linearities. Another procedure, probabilistic but heralded, consists in using a measurement-induced non-linearity via a conditional preparation technique operated on Gaussian states. Here, we detail this generation protocol for two non-Gaussian states, the single-photon state and a superposition of coherent states, using two differently phase-matched parametric oscillators as primary resources. This technique enables achievement of a high fidelity with the targeted state and generation of the state in a well-controlled spatiotemporal mode.

  5. Two and Three Beam Pumped Optical Parametric Amplifier of Chirped Pulses

    NASA Astrophysics Data System (ADS)

    Ališauskas, S.; Butkus, R.; Pyragaitė, V.; Smilgevičius, V.; Stabinis, A.; Piskarskas, A.

    2010-04-01

    We present two and three beam pumped optical parametric amplifier of broadband chirped pulses. The seed pulses from Ti:sapphire oscillator were stretched and amplified in a non-collinear geometry pumping with up to three beams derived from independent laser amplifiers. The signal with ˜90 nm bandwidth was amplified up to 0.72 mJ. The conversion efficiency dependence on intersection angles of pump beams is also revealed.

  6. Wide range operation of regenerative optical parametric wavelength converter using ASE-degraded 43-Gb/s RZ-DPSK signals.

    PubMed

    Gao, Mingyi; Kurumida, Junya; Namiki, Shu

    2011-11-07

    For sustainable growth of the Internet, wavelength-tunable optical regeneration is the key to scaling up high energy-efficiency dynamic optical path networks while keeping the flexibility of the network. Wavelength-tunable optical parametric regenerator (T-OPR) based on the gain saturation effect of parametric amplification in a highly nonlinear fiber is promising for noise reduction in phase-shift keying signals. In this paper, we experimentally evaluated the T-OPR performance for ASE-degraded 43-Gb/s RZ-DPSK signals over a 20-nm input wavelength range between 1527 nm and 1547 nm. As a result, we achieved improved power penalty performance for the regenerated idler with a proper pump power range.

  7. Astigmatism transfer phenomena in the optical parametric amplification process

    NASA Astrophysics Data System (ADS)

    Li, Wenkai; Chen, Yun; Li, Yanyan; Xu, Yi; Guo, Xiaoyang; Lu, Jun; Leng, Yuxin

    2017-01-01

    We numerically and experimentally investigate the astigmatism transfer phenomena in femtosecond optical parametric amplification (OPA). We model the OPA process based on the coupled second-order three-wave nonlinear propagation equations. The numerical and experimental results support that the input pump pulse astigmatism can be transferred into the idler pulse but not the signal pulse, and the idler pulse astigmatism originating from spatial walk-off is less than the idler pulse astigmatism received from the pump. Thus, we can provide a clear understanding of astigmatism transfer mechanisms in the OPA process, and make better use of broadband tunable OPA sources.

  8. Polarization switch of four-wave mixing in a lawtunable fiber optical parametric oscillator.

    PubMed

    Yang, Kangwen; Ye, Pengbo; Zheng, Shikai; Jiang, Jieshi; Huang, Kun; Hao, Qiang; Zeng, Heping

    2018-02-05

    We reported the simultaneous generation and selective manipulation of scalar and cross-phase modulation instabilities in a fiber optical parametric oscillator. Numerical and experimental results show independent control of parametric gain by changing the input pump polarization state. The resonant cavity enables power enhancement of 45 dB for the spontaneous sidebands, generating laser pulses tunable from 783 to 791 nm and 896 to 1005 nm due to the combination of four-wave mixing, cascaded Raman scattering and other nonlinear effects. This gain controlled, wavelength tunable, fiber-based laser source may find applications in the fields of nonlinear biomedical imaging and stimulated Raman spectroscopy.

  9. Squeezed light in an optical parametric oscillator network with coherent feedback quantum control.

    PubMed

    Crisafulli, Orion; Tezak, Nikolas; Soh, Daniel B S; Armen, Michael A; Mabuchi, Hideo

    2013-07-29

    We present squeezing and anti-squeezing spectra of the output from a degenerate optical parametric oscillator (OPO) network arranged in different coherent quantum feedback configurations. One OPO serves as a quantum plant, the other as a quantum controller. The addition of coherent feedback enables shaping of the output squeezing spectrum of the plant, and is found to be capable of pushing the frequency of maximum squeezing away from the optical driving frequency and broadening the spectrum over a wider frequency band. The experimental results are in excellent agreement with the developed theory, and illustrate the use of coherent quantum feedback to engineer the quantum-optical properties of the plant OPO output.

  10. Relaxation oscillation suppression in continuous-wave intracavity optical parametric oscillators.

    PubMed

    Stothard, David J M; Dunn, Malcolm H

    2010-01-18

    We report a solution to the long standing problem of the occurrence of spontaneous and long-lived bursts of relaxation oscillations which occur when a continuous-wave optical parametric oscillator is operated within the cavity of the parent pump-laser. By placing a second nonlinear crystal within the pump-wave cavity for the purpose of second-harmonic-generation of the pump-wave the additional nonlinear loss thereby arising due to up-conversion effectively suppresses the relaxation oscillations with very little reduction in down-converted power.

  11. Demonstration of optical parametric gain generation in the 1 μm regime based on a photonic crystal fiber pumped by a picosecond mode-locked ytterbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Yang, Si-Gang; Wang, Xiao-Jian; Gou, Dou-Dou; Chen, Hong-Wei; Chen, Ming-Hua; Xie, Shi-Zhong

    2014-01-01

    We report the experimental demonstration of the optical parametric gain generation in the 1 μm regime based on a photonic crystal fiber (PCF) with a zero group velocity dispersion (GVD) wavelength of 1062 nm pumped by a homemade tunable picosecond mode-locked ytterbium-doped fiber laser. A broad parametric gain band is obtained by pumping the PCF in the anomalous GVD regime with a relatively low power. Two separated narrow parametric gain bands are observed by pumping the PCF in the normal GVD regime. The peak of the parametric gain profile can be tuned from 927 to 1038 nm and from 1099 to 1228 nm. This widely tunable parametric gain band can be used for a broad band optical parametric amplifier, large span wavelength conversion or a tunable optical parametric oscillator.

  12. Direct fluorescence characterisation of a picosecond seeded optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    Stuart, N. H.; Bigourd, D.; Hill, R. W.; Robinson, T. S.; Mecseki, K.; Patankar, S.; New, G. H. C.; Smith, R. A.

    2015-02-01

    The temporal intensity contrast of high-power lasers based on optical parametric amplification (OPA) can be limited by parametric fluorescence from the non-linear gain stages. Here we present a spectroscopic method for direct measurement of unwanted parametric fluorescence widely applicable from unseeded to fully seeded and saturated OPA operation. Our technique employs simultaneous spectroscopy of fluorescence photons slightly outside the seed bandwidth and strongly attenuated light at the seed central wavelength. To demonstrate its applicability we have characterised the performance of a two-stage picosecond OPA pre-amplifier with 2.8×105 gain, delivering 335 μJ pulses at 1054 nm. We show that fluorescence from a strongly seeded OPA is reduced by ~500× from the undepleted to full pump depletion regimes. We also determine the vacuum fluctuation driven noise term seeding this OPA fluorescence to be 0.7±0.4 photons ps-1 nm-1 bandwidth. The resulting shot-to-shot statistics highlights a 1.5% probability of a five-fold and 0.3% probability of a ten-fold increase of fluorescence above the average value. Finally, we show that OPA fluorescence can be limited to a few-ps pedestal with 3×10-9 temporal intensity contrast 1.3 ps ahead of an intense laser pulse, a level highly attractive for large scale chirped-pulse OPA laser systems.

  13. Frequency non-degenerate phase-sensitive optical parametric amplification based on four-wave-mixing in width-modulated silicon waveguides.

    PubMed

    Wang, Zhaolu; Liu, Hongjun; Sun, Qibing; Huang, Nan; Li, Xuefeng

    2014-12-15

    A width-modulated silicon waveguide is proposed to realize non-degenerate phase sensitive optical parametric amplification. It is found that the relative phase at the input of the phase sensitive amplifier (PSA) θIn-PSA can be tuned by tailoring the width and length of the second segment of the width-modulated silicon waveguide, which will influence the gain in the parametric amplification process. The maximum gain of PSA is larger by 9 dB compared with the phase insensitive amplifier (PIA) gain, and the gain bandwidth of PSA is larger by 35 nm compared with the gain bandwidth of PIA. Our on-chip PSA can find important potential applications in highly integrated optical circuits for optical chip-to-chip communication and computers.

  14. Pushing the limits of CMOS optical parametric amplifiers with USRN:Si7N3 above the two-photon absorption edge

    PubMed Central

    Ooi, K. J. A.; Ng, D. K. T.; Wang, T.; Chee, A. K. L.; Ng, S. K.; Wang, Q.; Ang, L. K.; Agarwal, A. M.; Kimerling, L. C.; Tan, D. T. H.

    2017-01-01

    CMOS platforms operating at the telecommunications wavelength either reside within the highly dissipative two-photon regime in silicon-based optical devices, or possess small nonlinearities. Bandgap engineering of non-stoichiometric silicon nitride using state-of-the-art fabrication techniques has led to our development of USRN (ultra-silicon-rich nitride) in the form of Si7N3, that possesses a high Kerr nonlinearity (2.8 × 10−13 cm2 W−1), an order of magnitude larger than that in stoichiometric silicon nitride. Here we experimentally demonstrate high-gain optical parametric amplification using USRN, which is compositionally tailored such that the 1,550 nm wavelength resides above the two-photon absorption edge, while still possessing large nonlinearities. Optical parametric gain of 42.5 dB, as well as cascaded four-wave mixing with gain down to the third idler is observed and attributed to the high photon efficiency achieved through operating above the two-photon absorption edge, representing one of the largest optical parametric gains to date on a CMOS platform. PMID:28051064

  15. Four modes of optical parametric operation for squeezed state generation

    NASA Astrophysics Data System (ADS)

    Andersen, U. L.; Buchler, B. C.; Lam, P. K.; Wu, J. W.; Gao, J. R.; Bachor, H.-A.

    2003-11-01

    We report a versatile instrument, based on a monolithic optical parametric amplifier, which reliably generates four different types of squeezed light. We obtained vacuum squeezing, low power amplitude squeezing, phase squeezing and bright amplitude squeezing. We show a complete analysis of this light, including a full quantum state tomography. In addition we demonstrate the direct detection of the squeezed state statistics without the aid of a spectrum analyser. This technique makes the nonclassical properties directly visible and allows complete measurement of the statistical moments of the squeezed quadrature.

  16. Parametric imaging of collagen structural changes in human osteoarthritic cartilage using optical polarization tractography

    NASA Astrophysics Data System (ADS)

    Ravanfar, Mohammadreza; Pfeiffer, Ferris M.; Bozynski, Chantelle C.; Wang, Yuanbo; Yao, Gang

    2017-12-01

    Collagen degeneration is an important pathological feature of osteoarthritis. The purpose of this study is to investigate whether the polarization-sensitive optical coherence tomography (PSOCT)-based optical polarization tractography (OPT) can be useful in imaging collagen structural changes in human osteoarthritic cartilage samples. OPT eliminated the banding artifacts in conventional PSOCT by calculating the depth-resolved local birefringence and fiber orientation. A close comparison between OPT and PSOCT showed that OPT provided improved visualization and characterization of the zonal structure in human cartilage. Experimental results obtained in this study also underlined the importance of knowing the collagen fiber orientation in conventional polarized light microscopy assessment. In addition, parametric OPT imaging was achieved by quantifying the surface roughness, birefringence, and fiber dispersion in the superficial zone of the cartilage. These quantitative parametric images provided complementary information on the structural changes in cartilage, which can be useful for a comprehensive evaluation of collagen damage in osteoarthritic cartilage.

  17. Experimental demonstration of fiber optical parametric chirped-pulse amplification

    NASA Astrophysics Data System (ADS)

    Zhou, Yue; Cheung, Kim K. Y.; Chui, P. C.; Wong, Kenneth K. Y.

    2010-02-01

    A fiber optical parametric chirped-pulse amplifier (FOPCPA) is experimentally demonstrated. A 1.76 ps signal at 1542 nm with a peak power of 20 mW is broadened to 40 ps, and then amplified by a 100-ps pulsed pump at 1560 nm. The corresponding idler at 1578 nm is generated as the FOPCPA output. The same medium used to stretch the signal is deployed to compress the idler to 3.8 ps, and another spool of fiber is deployed to further compress the idler to 1.87 ps. The peak power of the compressed idler is 2 W, which corresponds to a gain of 20 dB.

  18. Shape sensing using multi-core fiber optic cable and parametric curve solutions.

    PubMed

    Moore, Jason P; Rogge, Matthew D

    2012-01-30

    The shape of a multi-core optical fiber is calculated by numerically solving a set of Frenet-Serret equations describing the path of the fiber in three dimensions. Included in the Frenet-Serret equations are curvature and bending direction functions derived from distributed fiber Bragg grating strain measurements in each core. The method offers advantages over prior art in that it determines complex three-dimensional fiber shape as a continuous parametric solution rather than an integrated series of discrete planar bends. Results and error analysis of the method using a tri-core optical fiber is presented. Maximum error expressed as a percentage of fiber length was found to be 7.2%.

  19. Temporal Simultons in Optical Parametric Oscillators

    NASA Astrophysics Data System (ADS)

    Jankowski, Marc; Marandi, Alireza; Phillips, C. R.; Hamerly, Ryan; Ingold, Kirk A.; Byer, Robert L.; Fejer, M. M.

    2018-02-01

    We report the first demonstration of a regime of operation in optical parametric oscillators (OPOs), in which the formation of temporal simultons produces stable femtosecond half-harmonic pulses. Simultons are simultaneous bright-dark solitons of a signal field at frequency ω and the pump field at 2 ω , which form in a quadratic nonlinear medium. The formation of simultons in an OPO is due to the interplay of nonlinear pulse acceleration with the timing mismatch between the pump repetition period and the cold-cavity round-trip time and is evidenced by sech2 spectra with broad instantaneous bandwidths when the resonator is detuned to a slightly longer round-trip time than the pump repetition period. We provide a theoretical description of an OPO operating in a regime dominated by these dynamics, observe the distinct features of simulton formation in an experiment, and verify our results with numerical simulations. These results represent a new regime of operation in nonlinear resonators, which can lead to efficient and scalable sources of few-cycle frequency combs at arbitrary wavelengths.

  20. Ground Demonstration of Planetary Gas Lidar Based on Optical Parametric Amplifier

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Li, Steve; Wu, Stewart; Kawa, Stephen R.; Krainak, Michael; Abshire, James

    2012-01-01

    We report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OPA output has high spectral purity and is widely tunable both at near-infrared and mid-infrared wavelengths, with an optical-optica1 conversion efficiency of up to approx 39 %. Using this laser source, we demonstrated open-path measurements of CH4 (3291 nm and 1651 nm), CO2 (1573 nm), H2O (1652 nm), and CO (4764 nm) on the ground. The simplicity, tunability. and power scalability of the OPA make it a strong candidate for general planetary lidar instruments, which will offer important information on the origins of the planet's geology, atmosphere, and potential for biology,

  1. Parametric spectro-temporal analyzer (PASTA) for real-time optical spectrum observation

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Xu, Jianbing; Chui, P. C.; Wong, Kenneth K. Y.

    2013-06-01

    Real-time optical spectrum analysis is an essential tool in observing ultrafast phenomena, such as the dynamic monitoring of spectrum evolution. However, conventional method such as optical spectrum analyzers disperse the spectrum in space and allocate it in time sequence by mechanical rotation of a grating, so are incapable of operating at high speed. A more recent method all-optically stretches the spectrum in time domain, but is limited by the allowable input condition. In view of these constraints, here we present a real-time spectrum analyzer called parametric spectro-temporal analyzer (PASTA), which is based on the time-lens focusing mechanism. It achieves a frame rate as high as 100 MHz and accommodates various input conditions. As a proof of concept and also for the first time, we verify its applications in observing the dynamic spectrum of a Fourier domain mode-locked laser, and the spectrum evolution of a laser cavity during its stabilizing process.

  2. Statistical properties of light from optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Vyas, Reeta; Singh, Surendra

    2009-12-01

    Coherence properties of light beams generated by optical parametric oscillators (OPOs) are discussed in the region of threshold. Analytic expressions, that are valid throughout the threshold region, for experimentally measurable quantities such as the mean and variance of photon number fluctuations, squeezing of field quadratures, and photon counting distributions are derived. These expressions describe non-Gaussian fluctuations of light in the region of threshold and reproduce Gaussian fluctuations below and above threshold, thus providing a bridge between below and above threshold regimes of operation. They are used to study the transformation of fluctuation properties of light as the OPOs make a transition from below to above threshold. The results for the OPOs are compared to those for the single-mode and two-mode lasers and their similarities and differences are discussed.

  3. Spectrally pure RF photonic source based on a resonant optical hyper-parametric oscillator

    NASA Astrophysics Data System (ADS)

    Liang, W.; Eliyahu, D.; Matsko, A. B.; Ilchenko, V. S.; Seidel, D.; Maleki, L.

    2014-03-01

    We demonstrate a free running 10 GHz microresonator-based RF photonic hyper-parametric oscillator characterized with phase noise better than -60 dBc/Hz at 10 Hz, -90 dBc/Hz at 100 Hz, and -150 dBc/Hz at 10 MHz. The device consumes less than 25 mW of optical power. A correlation between the frequency of the continuous wave laser pumping the nonlinear resonator and the generated RF frequency is confirmed. The performance of the device is compared with the performance of a standard optical fiber based coupled opto-electronic oscillator of OEwaves.

  4. Ground and Airborne Methane Measurements Using Optical Parametric Amplifiers

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Li, Steve; Wu, Stewart; Kawa, Stephan R.; Abshire, James Brice; Dawsey, Martha; Ramanathan, Anand

    2011-01-01

    We report on ground and airborne methane measurements with an active sensing instrument using widely tunable, seeded optical parametric generation (OPG). The technique has been used to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planetary bodies. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Carbon and methane emissions from land are expected to increase as permafrost melts exposing millennial-age carbon stocks to respiration (aerobic-CO2 and anaerobic-CH4) and fires. Methane emissions from c1athrates in the Arctic Ocean and on land are also likely to respond to climate warming. However, there is considerable uncertainty in present Arctic flux levels, as well as how fluxes will change with the changing environment. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. In this paper we report on remote sensing measurements of methane using a high peak power, widely tunable optical parametric generator (OPG) operating at 3.3 micrometers and 1.65 micrometers. We have demonstrated detection of methane at 3.3 micrometers and 1650 nanometers in an open path and compared them to accepted standards. We also report on preliminary airborne demonstration of methane measurements at 1.65 micrometers.

  5. 500 MW peak power degenerated optical parametric amplifier delivering 52 fs pulses at 97 kHz repetition rate.

    PubMed

    Rothhardt, J; Hädrich, S; Röser, F; Limpert, J; Tünnermann, A

    2008-06-09

    We present a high peak power degenerated parametric amplifier operating at 1030 nm and 97 kHz repetition rate. Pulses of a state-of-the art fiber chirped-pulse amplification (FCPA) system with 840 fs pulse duration and 410 microJ pulse energy are used as pump and seed source for a two stage optical parametric amplifier. Additional spectral broadening of the seed signal in a photonic crystal fiber creates enough bandwidth for ultrashort pulse generation. Subsequent amplification of the broadband seed signal in two 1 mm BBO crystals results in 41 microJ output pulse energy. Compression in a SF 11 prism compressor yields 37 microJ pulses as short as 52 fs. Thus, pulse shortening of more than one order of magnitude is achieved. Further scaling in terms of average power and pulse energy seems possible and will be discussed, since both concepts involved, the fiber laser and the parametric amplifier have the reputation to be immune against thermo-optical effects.

  6. Improving carrier-envelope phase stability in optical parametric chirped-pulse amplifiers by control of timing jitter.

    PubMed

    Hädrich, S; Rothhardt, J; Krebs, M; Demmler, S; Limpert, J; Tünnermann, A

    2012-12-01

    It is shown that timing jitter in optical parametric chirped-pulse amplification induces spectral drifts that transfer to carrier-envelope phase (CEP) instabilities via dispersion. Reduction of this effect requires temporal synchronization, which is realized with feedback obtained from the angularly dispersed idler. Furthermore, a novel method to measure the CEP drifts by utilizing parasitic second harmonic generation within parametric amplifiers is presented. Stabilization of the timing allows the obtainment of a CEP stability of 86 mrad over 40 min at 150 kHz repetition rate.

  7. Optomechanical design and construction of a vacuum-compatible optical parametric oscillator for generation of squeezed light.

    PubMed

    Wade, A R; Mansell, G L; McRae, T G; Chua, S S Y; Yap, M J; Ward, R L; Slagmolen, B J J; Shaddock, D A; McClelland, D E

    2016-06-01

    With the recent detection of gravitational waves, non-classical light sources are likely to become an essential element of future detectors engaged in gravitational wave astronomy and cosmology. Operating a squeezed light source under high vacuum has the advantages of reducing optical losses and phase noise compared to techniques where the squeezed light is introduced from outside the vacuum. This will ultimately provide enhanced sensitivity for modern interferometric gravitational wave detectors that will soon become limited by quantum noise across much of the detection bandwidth. Here we describe the optomechanical design choices and construction techniques of a near monolithic glass optical parametric oscillator that has been operated under a vacuum of 10(-6) mbar. The optical parametric oscillator described here has been shown to produce 8.6 dB of quadrature squeezed light in the audio frequency band down to 10 Hz. This performance has been maintained for periods of around an hour and the system has been under vacuum continuously for several months without a degradation of this performance.

  8. Optomechanical design and construction of a vacuum-compatible optical parametric oscillator for generation of squeezed light

    NASA Astrophysics Data System (ADS)

    Wade, A. R.; Mansell, G. L.; McRae, T. G.; Chua, S. S. Y.; Yap, M. J.; Ward, R. L.; Slagmolen, B. J. J.; Shaddock, D. A.; McClelland, D. E.

    2016-06-01

    With the recent detection of gravitational waves, non-classical light sources are likely to become an essential element of future detectors engaged in gravitational wave astronomy and cosmology. Operating a squeezed light source under high vacuum has the advantages of reducing optical losses and phase noise compared to techniques where the squeezed light is introduced from outside the vacuum. This will ultimately provide enhanced sensitivity for modern interferometric gravitational wave detectors that will soon become limited by quantum noise across much of the detection bandwidth. Here we describe the optomechanical design choices and construction techniques of a near monolithic glass optical parametric oscillator that has been operated under a vacuum of 10-6 mbar. The optical parametric oscillator described here has been shown to produce 8.6 dB of quadrature squeezed light in the audio frequency band down to 10 Hz. This performance has been maintained for periods of around an hour and the system has been under vacuum continuously for several months without a degradation of this performance.

  9. Development of Optical Parametric Amplifier for Lidar Measurements of Trace Gases on Earth and Mars

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Riris, Haris; Li, Steve; Wu, Stewart; Kawa, Stephen R.; Krainak, Michael; Abshire, James

    2011-01-01

    Trace gases in planetary atmospheres offer important clues as to the origins of the planet's hydrology, geology. atmosphere. and potential for biology. Wc report on the development effort of a nanosecond-pulsed optical parametric amplifier (OPA) for remote trace gas measurements for Mars and Earth. The OP A output light is single frequency with high spectral purity and is widely tunable both at 1600 nm and 3300 nm with an optical-optical conversion efficiency of approximately 40%. We demonstrated open-path atmospheric measurements ofCH4 (3291 nm and 1651 nm). CO2 (1573 nm), H20 (1652 nm) with this laser source.

  10. Dispersion management for a sub-10-fs, 10 TW optical parametric chirped-pulse amplifier.

    PubMed

    Tavella, Franz; Nomura, Yutaka; Veisz, Laszlo; Pervak, Vladimir; Marcinkevicius, Andrius; Krausz, Ferenc

    2007-08-01

    We report the amplification of three-cycle, 8.5 fs optical pulses in a near-infrared noncollinear optical parametric chirped-pulse amplifier (OPCPA) up to energies of 80 mJ. Improved dispersion management in the amplifier by means of a combination of reflection grisms and a chirped-mirror stretcher allowed us to recompress the amplified pulses to within 6% of their Fourier limit. The novel ultrabroad, ultraprecise dispersion control technology presented in this work opens the way to scaling multiterawatt technology to even shorter pulses by optimizing the OPCPA bandwidth.

  11. Towards a petawatt-class few-cycle infrared laser system via dual-chirped optical parametric amplification.

    PubMed

    Fu, Yuxi; Midorikawa, Katsumi; Takahashi, Eiji J

    2018-05-16

    Expansion of the wavelength range for an ultrafast laser is an important ingredient for extending its range of applications. Conventionally, optical parametric amplification (OPA) has been employed to expand the laser wavelength to the infrared (IR) region. However, the achievable pulse energy and peak power have been limited to the mJ and the GW level, respectively. A major difficulty in the further energy scaling of OPA results from a lack of suitable large nonlinear crystals. Here, we circumvent this difficulty by employing a dual-chirped optical parametric amplification (DC-OPA) scheme. We successfully generate a multi-TW IR femtosecond laser pulse with an energy of 100 mJ order, which is higher than that reported in previous works. We also obtain excellent energy scaling ability, ultrashort pulses, flexiable wavelength tunability, and high-energy stability, which prove that DC-OPA is a superior method for the energy scaling of IR pulses to the 10 J/PW level.

  12. Coherent frequency division with a degenerate synchronously pumped optical parametric oscillator.

    PubMed

    Wan, Chenchen; Li, Peng; Ruehl, Axel; Hartl, Ingmar

    2018-03-01

    Synchronously pumped optical parametric oscillators (OPOs) are important tools for frequency comb (FC) generation in the mid-IR spectral range, where few suitable laser gain materials exist. For degenerate OPOs, self-phase-locking to the pump FC has been demonstrated. Here, we present a phase noise study of the carrier envelope offset frequency, revealing a -6  dB reduction compared to the pump FC over a wide Fourier frequency range. These results demonstrate that a degenerate OPO can be an ideal coherent frequency divider without any excess noise.

  13. Quantum correlation in degenerate optical parametric oscillators with mutual injections

    NASA Astrophysics Data System (ADS)

    Takata, Kenta; Marandi, Alireza; Yamamoto, Yoshihisa

    2015-10-01

    We theoretically and numerically study the quantum dynamics of two degenerate optical parametric oscillators with mutual injections. The cavity mode in the optical coupling path between the two oscillator facets is explicitly considered. Stochastic equations for the oscillators and mutual injection path based on the positive P representation are derived. The system of two gradually pumped oscillators with out-of-phase mutual injections is simulated, and its quantum state is investigated. When the incoherent loss of the oscillators other than the mutual injections is small, the squeezed quadratic amplitudes p ̂ in the oscillators are positively correlated near the oscillation threshold. It indicates finite quantum correlation, estimated via Gaussian quantum discord, and the entanglement between the intracavity subharmonic fields. When the loss in the injection path is low, each oscillator around the phase transition point forms macroscopic superposition even under a small pump noise. It suggests that the squeezed field stored in the low-loss injection path weakens the decoherence in the oscillators.

  14. A continuous-wave, widely tunable, intra-cavity, singly resonant, magnesium-doped, periodically poled lithium niobate optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Li, Z. P.; Duan, Y. M.; Wu, K. R.; Zhang, G.; Zhu, H. Y.; Wang, X. L.; Chen, Y. H.; Xue, Z. Q.; Lin, Q.; Song, G. C.; Su, H.

    2013-05-01

    We report a continuous-wave (CW), intra-cavity singly resonant optical parametric oscillator (OPO), based on periodically poled MgO:LiNbO3 pumped by a diode-end-pumped CW Nd:YVO4 laser, and calculate the gain of optical parametric amplification as a function of pump beam waist (at 1064 nm) in the singly resonant OPO (SRO) cavity, to balance the mode-matching and the intensity for the higher gain of a signal wave in the operation of the SRO. In order to achieve maximum gain, we use a convex lens to limit the 1064 nm beam waist. In the experiment, a tunable signal output from 1492 to 1614 nm and an idler output from 3122 to 3709 nm are obtained. For an 808 nm pump power of 11.5 W, a maximum signal output power of up to 2.48 W at 1586 nm and an idler output power of 1.1 W at 3232 nm are achieved with a total optical-to-optical conversion efficiency of 31%.

  15. Partially deuterated potassium dihydrogen phosphate optimized for ultra-broadband optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Fujioka, K.; Fujimoto, Y.; Tsubakimoto, K.; Kawanaka, J.; Shoji, I.; Miyanaga, N.

    2015-03-01

    The refractive index of a potassium dihydrogen phosphate (KDP) crystal strongly depends on the deuteration fraction of the crystal. The wavelength dependence of the phase-matching angle in the near-infrared optical parametric process shows convex and concave characteristics for pure KDP and pure deuterated KDP (DKDP), respectively, when pumped by the second harmonic of Nd- or Yb-doped solid state lasers. Using these characteristics, ultra-broadband phase matching can be realized by optimization of the deuteration fraction. The refractive index of DKDP that was grown with a different deuteration fraction (known as partially deuterated KDP or pDKDP) was measured over a wide wavelength range of 0.4-1.5 μm by the minimum deviation method. The wavelength dispersions of the measured refractive indices were fitted using a modified Sellmeier equation, and the deuteration fraction dependence was analyzed using the Lorentz-Lorenz equation. The wavelength-dependent phase-matching angle for an arbitrary deuteration fraction was then calculated for optical parametric amplification with pumping at a wavelength of 526.5 nm. The results revealed that a refractive index database with precision of more than 2 × 10-5 was necessary for exact evaluation of the phase-matching condition. An ultra-broad gain bandwidth of up to 490 nm will be feasible when using the 68% pDKDP crystal.

  16. Spectral line narrowing in PPLN OPO devices for 1-μm wavelength doubling

    NASA Astrophysics Data System (ADS)

    Perrett, Brian J.; Terry, Jonathan A. C.; Mason, Paul D.; Orchard, David A.

    2004-12-01

    One route to generating mid-infrared (mid-IR) radiation is through a two-stage non-linear conversion process from the near-IR, exploiting powerful neodymium lasers operating at wavelengths close to 1 μm. In the first stage of this process non-linear conversion within a degenerate optical parametric oscillator (OPO) is used to double the wavelength of the 1 μm laser. The resultant 2 μm radiation is then used to pump a second OPO, based on a material such as ZGP, for conversion into the 3 to 5 μm mid-IR waveband. Periodically poled lithium niobate (PPLN) is a useful material for conversion from 1 to 2 μm due to its high non-linear coefficient (deff ~ 16 pm/V) and the long crystal lengths available (up to 50 mm). Slope efficiencies in excess of 40% have readily been achieved using a simple plane-plane resonator when pumped at 10 kHz with 3.5 mJ pulses from a 1.047 μm Nd:YLF laser. However, the OPO output was spectrally broad at degeneracy with a measured full-width-half-maximum (FWHM) linewidth of approximately 65 nm. This output linewidth is significantly broader than the spectral acceptance bandwidth of ZGP for conversion into the mid-IR. In this paper techniques for spectral narrowing the output from a degenerate PPLN OPO are investigated using two passive elements, a diffraction grating and an air spaced etalon. Slope efficiencies approaching 20% have been obtained using the grating in a dog-leg cavity configuration producing spectrally narrow 2 μm output with linewidths as low as 2 nm. A grating-narrowed degenerate PPLN OPO has been successfully used to pump a ZGP OPO.

  17. Parametric optimization of optical signal detectors employing the direct photodetection scheme

    NASA Astrophysics Data System (ADS)

    Kirakosiants, V. E.; Loginov, V. A.

    1984-08-01

    The problem of optimization of the optical signal detection scheme parameters is addressed using the concept of a receiver with direct photodetection. An expression is derived which accurately approximates the field of view (FOV) values obtained by a direct computer minimization of the probability of missing a signal; optimum values of the receiver FOV were found for different atmospheric conditions characterized by the number of coherence spots and the intensity fluctuations of a plane wave. It is further pointed out that the criterion presented can be possibly used for parametric optimization of detectors operating in accordance with the Neumann-Pearson criterion.

  18. Pattern formation without diffraction matching in optical parametric oscillators with a metamaterial.

    PubMed

    Tassin, Philippe; Van der Sande, Guy; Veretennicoff, Irina; Kockaert, Pascal; Tlidi, Mustapha

    2009-05-25

    We consider a degenerate optical parametric oscillator containing a left-handed material. We show that the inclusion of a left-handed material layer allows for controlling the strength and sign of the diffraction coefficient at either the pump or the signal frequency. Subsequently, we demonstrate the existence of stable dissipative structures without diffraction matching, i.e., without the usual relationship between the diffraction coefficients of the signal and pump fields. Finally, we investigate the size scaling of these light structures with decreasing diffraction strength.

  19. Highly stable ultrabroadband mid-IR optical parametric chirped-pulse amplifier optimized for superfluorescence suppression.

    PubMed

    Moses, J; Huang, S-W; Hong, K-H; Mücke, O D; Falcão-Filho, E L; Benedick, A; Ilday, F O; Dergachev, A; Bolger, J A; Eggleton, B J; Kärtner, F X

    2009-06-01

    We present a 9 GW peak power, three-cycle, 2.2 microm optical parametric chirped-pulse amplification source with 1.5% rms energy and 150 mrad carrier envelope phase fluctuations. These characteristics, in addition to excellent beam, wavefront, and pulse quality, make the source suitable for long-wavelength-driven high-harmonic generation. High stability is achieved by careful optimization of superfluorescence suppression, enabling energy scaling.

  20. Mirrorless Optical Parametric Oscillation with Tunable Threshold in Cold Atoms.

    PubMed

    Mei, Yefeng; Guo, Xianxin; Zhao, Luwei; Du, Shengwang

    2017-10-13

    We report the demonstration of a mirrorless optical parametric oscillator with a tunable threshold in laser-cooled atoms with four-wave mixing (FWM) using electromagnetically induced transparency. Driven by two classical laser beams, the generated Stokes and anti-Stokes fields counterpropagate and build up efficient intrinsic feedback through the nonlinear FWM process. This feedback does not involve any cavity or spatially distributed microstructures. We observe the transition of photon correlation properties from the biphoton quantum regime (below the threshold) to the oscillation regime (above the threshold). The pump threshold can be tuned by varying the operating parameters. We achieve the oscillation with a threshold as low as 15  μW.

  1. Self-consistent projection operator theory in nonlinear quantum optical systems: A case study on degenerate optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Degenfeld-Schonburg, Peter; Navarrete-Benlloch, Carlos; Hartmann, Michael J.

    2015-05-01

    Nonlinear quantum optical systems are of paramount relevance for modern quantum technologies, as well as for the study of dissipative phase transitions. Their nonlinear nature makes their theoretical study very challenging and hence they have always served as great motivation to develop new techniques for the analysis of open quantum systems. We apply the recently developed self-consistent projection operator theory to the degenerate optical parametric oscillator to exemplify its general applicability to quantum optical systems. We show that this theory provides an efficient method to calculate the full quantum state of each mode with a high degree of accuracy, even at the critical point. It is equally successful in describing both the stationary limit and the dynamics, including regions of the parameter space where the numerical integration of the full problem is significantly less efficient. We further develop a Gaussian approach consistent with our theory, which yields sensibly better results than the previous Gaussian methods developed for this system, most notably standard linearization techniques.

  2. Thermal effects in an ultrafast BiB 3O 6 optical parametric oscillator at high average powers

    DOE PAGES

    Petersen, T.; Zuegel, J. D.; Bromage, J.

    2017-08-15

    An ultrafast, high-average-power, extended-cavity, femtosecond BiB 3O 6 optical parametric oscillator was constructed as a test bed for investigating the scalability of infrared parametric devices. Despite the high pulse energies achieved by this system, the reduction in slope efficiency near the maximum-available pump power prompted the investigation of thermal effects in the crystal during operation. Furthermore, the local heating effects in the crystal were used to determine the impact on both phase matching and thermal lensing to understand limitations that must be overcome to achieve microjoule-level pulse energies at high repetition rates.

  3. Thermal effects in an ultrafast BiB 3O 6 optical parametric oscillator at high average powers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Petersen, T.; Zuegel, J. D.; Bromage, J.

    An ultrafast, high-average-power, extended-cavity, femtosecond BiB 3O 6 optical parametric oscillator was constructed as a test bed for investigating the scalability of infrared parametric devices. Despite the high pulse energies achieved by this system, the reduction in slope efficiency near the maximum-available pump power prompted the investigation of thermal effects in the crystal during operation. Furthermore, the local heating effects in the crystal were used to determine the impact on both phase matching and thermal lensing to understand limitations that must be overcome to achieve microjoule-level pulse energies at high repetition rates.

  4. Heralded creation of photonic qudits from parametric down-conversion using linear optics

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Jun-ichi; Bergmann, Marcel; van Loock, Peter; Fuwa, Maria; Okada, Masanori; Takase, Kan; Toyama, Takeshi; Makino, Kenzo; Takeda, Shuntaro; Furusawa, Akira

    2018-05-01

    We propose an experimental scheme to generate, in a heralded fashion, arbitrary quantum superpositions of two-mode optical states with a fixed total photon number n based on weakly squeezed two-mode squeezed state resources (obtained via weak parametric down-conversion), linear optics, and photon detection. Arbitrary d -level (qudit) states can be created this way where d =n +1 . Furthermore, we experimentally demonstrate our scheme for n =2 . The resulting qutrit states are characterized via optical homodyne tomography. We also discuss possible extensions to more than two modes concluding that, in general, our approach ceases to work in this case. For illustration and with regards to possible applications, we explicitly calculate a few examples such as NOON states and logical qubit states for quantum error correction. In particular, our approach enables one to construct bosonic qubit error-correction codes against amplitude damping (photon loss) with a typical suppression of √{n }-1 losses and spanned by two logical codewords that each correspond to an n -photon superposition for two bosonic modes.

  5. Program Predicts Performance of Optical Parametric Oscillators

    NASA Technical Reports Server (NTRS)

    Cross, Patricia L.; Bowers, Mark

    2006-01-01

    A computer program predicts the performances of solid-state lasers that operate at wavelengths from ultraviolet through mid-infrared and that comprise various combinations of stable and unstable resonators, optical parametric oscillators (OPOs), and sum-frequency generators (SFGs), including second-harmonic generators (SHGs). The input to the program describes the signal, idler, and pump beams; the SFG and OPO crystals; and the laser geometry. The program calculates the electric fields of the idler, pump, and output beams at three locations (inside the laser resonator, just outside the input mirror, and just outside the output mirror) as functions of time for the duration of the pump beam. For each beam, the electric field is used to calculate the fluence at the output mirror, plus summary parameters that include the centroid location, the radius of curvature of the wavefront leaving through the output mirror, the location and size of the beam waist, and a quantity known, variously, as a propagation constant or beam-quality factor. The program provides a typical Windows interface for entering data and selecting files. The program can include as many as six plot windows, each containing four graphs.

  6. Optomechanical design and construction of a vacuum-compatible optical parametric oscillator for generation of squeezed light

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wade, A. R.; Mansell, G. L.; McRae, T. G., E-mail: Terry.Mcrae@anu.edu.au

    With the recent detection of gravitational waves, non-classical light sources are likely to become an essential element of future detectors engaged in gravitational wave astronomy and cosmology. Operating a squeezed light source under high vacuum has the advantages of reducing optical losses and phase noise compared to techniques where the squeezed light is introduced from outside the vacuum. This will ultimately provide enhanced sensitivity for modern interferometric gravitational wave detectors that will soon become limited by quantum noise across much of the detection bandwidth. Here we describe the optomechanical design choices and construction techniques of a near monolithic glass opticalmore » parametric oscillator that has been operated under a vacuum of 10{sup −6} mbar. The optical parametric oscillator described here has been shown to produce 8.6 dB of quadrature squeezed light in the audio frequency band down to 10 Hz. This performance has been maintained for periods of around an hour and the system has been under vacuum continuously for several months without a degradation of this performance.« less

  7. Performance scaling via passive pulse shaping in cavity-enhanced optical parametric chirped-pulse amplification.

    PubMed

    Siddiqui, Aleem M; Moses, Jeffrey; Hong, Kyung-Han; Lai, Chien-Jen; Kärtner, Franz X

    2010-06-15

    We show that an enhancement cavity seeded at the full repetition rate of the pump laser can automatically reshape small-signal gain across the interacting pulses in an optical parametric chirped-pulse amplifier for close-to-optimal operation, significantly increasing both the gain bandwidth and the conversion efficiency, in addition to boosting gain for high-repetition-rate amplification. Applied to a degenerate amplifier, the technique can provide an octave-spanning gain bandwidth.

  8. Dual-channel operation in a synchronously pumped optical parametric oscillator for the generation of broadband mid-infrared coherent light sources.

    PubMed

    Liu, Pei; Wang, Sicong; He, Puyuan; Zhang, Zhaowei

    2018-05-01

    We report, to the best of our knowledge, a novel approach for generating broadband mid-infrared (mid-IR) light by implementing a dual-channel scheme in a synchronously pumped optical parametric oscillator (SPOPO). Two-channel operation was achieved by inserting a prism pair and two reflection mirrors inside an optical parametric oscillator (OPO) cavity. Pumped by a Yb-fiber laser, the OPO generated an idler wave at ∼3150  nm with a -10  dB bandwidth of ∼13.2  THz, which was twice as much as that of the pump source. This scheme represents a promising technical route to transform conventional SPOPOs into a device capable of generating mid-IR light with very broad instantaneous bandwidth.

  9. Closed-loop wavelength stabilization of an optical parametric oscillator as a front end of a high-power iodine laser chain.

    PubMed

    Kral, L

    2007-05-01

    We present a complex stabilization and control system for a commercially available optical parametric oscillator. The system is able to stabilize the oscillator's output wavelength at a narrow spectral line of atomic iodine with subpicometer precision, allowing utilization of this solid-state parametric oscillator as a front end of a high-power photodissociation laser chain formed by iodine gas amplifiers. In such setup, a precise wavelength matching between the front end and the amplifier chain is necessary due to extremely narrow spectral lines of the gaseous iodine (approximately 20 pm). The system is based on a personal computer, a heated iodine cell, and a few other low-cost components. It automatically identifies the proper peak within the iodine absorption spectrum, and then keeps the oscillator tuned to this peak with high precision and reliability. The use of the solid-state oscillator as the front end allows us to use the whole iodine laser system as a pump laser for the optical parametric chirped pulse amplification, as it enables precise time synchronization with a signal Ti:sapphire laser.

  10. Multi-channel lock-in amplifier assisted femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy with efficient rejection of superfluorescence background.

    PubMed

    Mao, Pengcheng; Wang, Zhuan; Dang, Wei; Weng, Yuxiang

    2015-12-01

    Superfluorescence appears as an intense background in femtosecond time-resolved fluorescence noncollinear optical parametric amplification spectroscopy, which severely interferes the reliable acquisition of the time-resolved fluorescence spectra especially for an optically dilute sample. Superfluorescence originates from the optical amplification of the vacuum quantum noise, which would be inevitably concomitant with the amplified fluorescence photons during the optical parametric amplification process. Here, we report the development of a femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectrometer assisted with a 32-channel lock-in amplifier for efficient rejection of the superfluorescence background. With this spectrometer, the superfluorescence background signal can be significantly reduced to 1/300-1/100 when the seeding fluorescence is modulated. An integrated 32-bundle optical fiber is used as a linear array light receiver connected to 32 photodiodes in one-to-one mode, and the photodiodes are further coupled to a home-built 32-channel synchronous digital lock-in amplifier. As an implementation, time-resolved fluorescence spectra for rhodamine 6G dye in ethanol solution at an optically dilute concentration of 10(-5)M excited at 510 nm with an excitation intensity of 70 nJ/pulse have been successfully recorded, and the detection limit at a pump intensity of 60 μJ/pulse was determined as about 13 photons/pulse. Concentration dependent redshift starting at 30 ps after the excitation in time-resolved fluorescence spectra of this dye has also been observed, which can be attributed to the formation of the excimer at a higher concentration, while the blueshift in the earlier time within 10 ps is attributed to the solvation process.

  11. Multi-channel lock-in amplifier assisted femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectroscopy with efficient rejection of superfluorescence background

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mao, Pengcheng; Wang, Zhuan; Dang, Wei

    Superfluorescence appears as an intense background in femtosecond time-resolved fluorescence noncollinear optical parametric amplification spectroscopy, which severely interferes the reliable acquisition of the time-resolved fluorescence spectra especially for an optically dilute sample. Superfluorescence originates from the optical amplification of the vacuum quantum noise, which would be inevitably concomitant with the amplified fluorescence photons during the optical parametric amplification process. Here, we report the development of a femtosecond time-resolved fluorescence non-collinear optical parametric amplification spectrometer assisted with a 32-channel lock-in amplifier for efficient rejection of the superfluorescence background. With this spectrometer, the superfluorescence background signal can be significantly reduced to 1/300–1/100more » when the seeding fluorescence is modulated. An integrated 32-bundle optical fiber is used as a linear array light receiver connected to 32 photodiodes in one-to-one mode, and the photodiodes are further coupled to a home-built 32-channel synchronous digital lock-in amplifier. As an implementation, time-resolved fluorescence spectra for rhodamine 6G dye in ethanol solution at an optically dilute concentration of 10{sup −5}M excited at 510 nm with an excitation intensity of 70 nJ/pulse have been successfully recorded, and the detection limit at a pump intensity of 60 μJ/pulse was determined as about 13 photons/pulse. Concentration dependent redshift starting at 30 ps after the excitation in time-resolved fluorescence spectra of this dye has also been observed, which can be attributed to the formation of the excimer at a higher concentration, while the blueshift in the earlier time within 10 ps is attributed to the solvation process.« less

  12. Quantum noise and squeezing in optical parametric oscillator with arbitrary output coupling

    NASA Technical Reports Server (NTRS)

    Prasad, Sudhakar

    1993-01-01

    The redistribution of intrinsic quantum noise in the quadratures of the field generated in a sub-threshold degenerate optical parametric oscillator exhibits interesting dependences on the individual output mirror transmittances, when they are included exactly. We present a physical picture of this problem, based on mirror boundary conditions, which is valid for arbitrary transmittances. Hence, our picture applies uniformly to all values of the cavity Q factor representing, in the opposite extremes, both perfect oscillator and amplifier configurations. Beginning with a classical second-harmonic pump, we shall generalize our analysis to the finite amplitude and phase fluctuations of the pump.

  13. Combined Yb/Nd driver for optical parametric chirped pulse amplifiers.

    PubMed

    Michailovas, Kirilas; Baltuska, Andrius; Pugzlys, Audrius; Smilgevicius, Valerijus; Michailovas, Andrejus; Zaukevicius, Audrius; Danilevicius, Rokas; Frankinas, Saulius; Rusteika, Nerijus

    2016-09-19

    We report on the developed front-end/pump system for optical parametric chirped pulse amplifiers. The system is based on a dual output fiber oscillator/power amplifier which seeds and assures all-optical synchronization of femtosecond Yb and picosecond Nd laser amplifiers operating at a central wavelength of 1030 nm and 1064 nm, respectively. At the central wavelength of 1030 nm, the fiber oscillator generates partially stretched 4 ps pulses with the spectrum supporting a <120 fs pulse duration and pulse energy of 0.45 nJ. The energy of generated 1064 nm pulses is 0.15 nJ, which is sufficient for the efficient seeding of high-contrast Nd:YVO chirped pulse regenerative amplifier/post amplifier systems generating 9 mJ pulses compressible to 16 ps duration. The power amplification stages, based on Nd:YAG crystals, provide 62 mJ pulses compressible to 20 ps pulse duration at a repetition rate of 1 kHz. Further energy scaling currently is prevented by limited dimensions of the diffraction gratings, which, because of the fast progress in MLD grating manufacturing technologies is only a temporary obstacle.

  14. General analysis of group velocity effects in collinear optical parametric amplifiers and generators.

    PubMed

    Arisholm, Gunnar

    2007-05-14

    Group velocity mismatch (GVM) is a major concern in the design of optical parametric amplifiers (OPAs) and generators (OPGs) for pulses shorter than a few picoseconds. By simplifying the coupled propagation equations and exploiting their scaling properties, the number of free parameters for a collinear OPA is reduced to a level where the parameter space can be studied systematically by simulations. The resulting set of figures show the combinations of material parameters and pulse lengths for which high performance can be achieved, and they can serve as a basis for a design.

  15. Optical parametric amplifiers using chirped quasi-phase-matching gratings I: practical design formulas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, M. M.

    Optical parametric amplifiers using chirped quasi-phase-matching (QPM) gratings offer the possibility of engineering the gain and group delay spectra. We give practical formulas for the design of such amplifiers. We consider linearly chirped QPM gratings providing constant gain over a broad bandwidth, sinusoidally modulated profiles for selective frequency amplification and a pair of QPM gratings working in tandem to ensure constant gain and constant group delay at the same time across the spectrum. Finally, the analysis is carried out in the frequency domain using Wentzel–Kramers–Brillouin analysis.

  16. Generation of polarization squeezed light with an optical parametric amplifier at 795 nm

    NASA Astrophysics Data System (ADS)

    Han, Yashuai; Wen, Xin; Liu, Jinyu; He, Jun; Wang, Junmin

    2018-06-01

    We report the experimental demonstration of polarization squeezed beam at 795 nm by combining a quadrature amplitude squeezed beam with an in-phase bright coherent beam. The quadrature amplitude squeezed beam is generated by a degenerate optical parametric amplifier based on a PPKTP crystal. Stokes operators Sˆ2 squeezing of -3.8 dB and Sˆ3 anti-squeezing of +5.0 dB have been observed. This polarization squeezed beam resonant to rubidium D1 line has potential applications in quantum information networks and precision measurement beyond the shot noise limit.

  17. Intracavity-pumped Raman laser action in a mid IR, continuous-wave (cw) MgO:PPLN optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Okishev, Andrey V.; Zuegel, Jonathan D.

    2006-12-01

    Intracavity-pumped Raman laser action in a fiber-laser pumped, single-resonant, continuous-wave (cw) MgO:PPLN optical parametric oscillator with a high-Q linear resonator has been observed for the first time to our knowledge. Experimental results of this phenomenon investigation will be discussed.

  18. Unstable Resonator Optical Parametric Oscillator Based on Quasi-Phase-Matched RbTiOAsO(4).

    PubMed

    Hansson, G; Karlsson, H; Laurell, F

    2001-10-20

    We demonstrate improved signal and idler-beam quality of a 3-mm-aperture quasi-phase-matched RbTiOAsO(4) optical parametric oscillator through use of a confocal unstable resonator as compared with a plane-parallel resonator. Both oscillators were singly resonant, and the periodically poled RbTiOAsO(4) crystal generated a signal at 1.56 mum and an idler at 3.33 mum when pumped at 1.064 mum. We compared the beam quality produced by the 1.2-magnification confocal unstable resonator with the beam quality produced by the plane-parallel resonator by measuring the signal and the idler beam M(2) value. We also investigated the effect of pump-beam intensity distribution by comparing the result of a Gaussian and a top-hat intensity profile pump beam. We generated a signal beam of M(2) approximately 7 and an idler beam of M(2) approximately 2.5 through use of an unstable resonator and a Gaussian intensity profile pump beam. This corresponds to an increase of a factor of approximately 2 in beam quality for the signal and a factor of 3 for the idler, compared with the beam quality of the plane-parallel resonator optical parametric oscillator.

  19. Intracavity KTP optical parametric oscillator driven by a KLM Nd:GGG laser with a single AO modulator

    NASA Astrophysics Data System (ADS)

    Chu, Hongwei; Zhao, Shengzhi; Yang, Kejian; Zhao, Jia; Li, Yufei; Li, Tao; Li, Guiqiu; Li, Dechun; Qiao, Wenchao

    2015-05-01

    An intracavity KTiOPO4 (KTP) optical parametric oscillator (OPO) pumped by a Kerr lens mode-locking (KLM) Nd:GGG laser near 1062 nm with a single AO modulator was realized for the first time. The mode-locking pulses of the signal wave were obtained with a short duration of subnanosecond and a repetition rate of several kilohertz (kHz). Under a diode pump power of 8.25 W, a maximum output power of 104 mW at signal wavelength near 1569 nm was obtained at a repetition rate of 2 kHz. The highest pulse energy and peak power were estimated to be 80 μJ and 102 kW at a repetition rate of 1 kHz, respectively. The shortest pulse duration was measured to be 749 ps. By considering the Gaussian spatial distribution of the photon density and the Kerr-lens effect in the gain medium, a set of the coupled rate equations for QML intracavity optical parametric oscillator are given and the numerical simulations are basically fitted with the experimental results.

  20. Research on High-Intensity Picosecond Pump Laser in Short Pulse Optical Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Pan, Xue; Peng, Yu-Jie; Wang, Jiang-Feng; Lu, Xing-Hua; Ouyang, Xiao-Ping; Chen, Jia-Lin; Jiang, You-En; Fan, Wei; Li, Xue-Chun

    2013-01-01

    A 527 nm pump laser generating 1.7 mJ energy with peak power of more than 0.12 GW is demonstrated. The theoretical simulation result shows that it has 106 gain in the picosecond-pump optical parametric chirped pulse amplification when the pump laser peak power is 0.1 GW and the intensity is more than 5 GW/cm2, and that it can limit the parametric fluorescence in the picosecond time scale of pump duration. The pump laser system adopts a master-oscillator power amplifier, which integrates a more than 30 pJ fiber-based oscillator with a 150 μJ regenerative amplifier and a relay-imaged four-pass diode-pump Nd glass amplifier to generate a 1 Hz top hat spatial beam and about 14 ps temporal Guassian pulse with <2% pulse-to-pulse energy stability. The output energy of the power amplifier is limited to 4 mJ for B-integral concern, and the frequency doubling efficiency can reach 65% with input intensity 10 GW/cm2.

  1. Investigation of the photon statistics of parametric fluorescence in a traveling-wave parametric amplifier by means of self-homodyne tomography.

    PubMed

    Vasilyev, M; Choi, S K; Kumar, P; D'Ariano, G M

    1998-09-01

    Photon-number distributions for parametric fluorescence from a nondegenerate optical parametric amplifier are measured with a novel self-homodyne technique. These distributions exhibit the thermal-state character predicted by theory. However, a difference between the fluorescence gain and the signal gain of the parametric amplifier is observed. We attribute this difference to a change in the signal-beam profile during the traveling-wave pulsed amplification process.

  2. Controlled Asymmetry of Einstein-Podolsky-Rosen Steering with an Injected Nondegenerate Optical Parametric Oscillator

    NASA Astrophysics Data System (ADS)

    Olsen, M. K.

    2017-10-01

    We propose and analyze a nonlinear optical apparatus in which the direction of asymmetric steering is controllable within the apparatus, rather than by adding noise to measurements. Using a nondegenerate parametric oscillator with an injected signal field, we show how the directionality and extent of the steering can be readily controlled for output modes that can be up to one octave apart. The two down-converted modes, which exhibit the greater violations of the steering inequalities, can also be controlled to exhibit asymmetric steering in some regimes.

  3. Boltzmann sampling for an XY model using a non-degenerate optical parametric oscillator network

    NASA Astrophysics Data System (ADS)

    Takeda, Y.; Tamate, S.; Yamamoto, Y.; Takesue, H.; Inagaki, T.; Utsunomiya, S.

    2018-01-01

    We present an experimental scheme of implementing multiple spins in a classical XY model using a non-degenerate optical parametric oscillator (NOPO) network. We built an NOPO network to simulate a one-dimensional XY Hamiltonian with 5000 spins and externally controllable effective temperatures. The XY spin variables in our scheme are mapped onto the phases of multiple NOPO pulses in a single ring cavity and interactions between XY spins are implemented by mutual injections between NOPOs. We show the steady-state distribution of optical phases of such NOPO pulses is equivalent to the Boltzmann distribution of the corresponding XY model. Estimated effective temperatures converged to the setting values, and the estimated temperatures and the mean energy exhibited good agreement with the numerical simulations of the Langevin dynamics of NOPO phases.

  4. Direct generation of spatial quadripartite continuous variable entanglement in an optical parametric oscillator.

    PubMed

    Liu, Kui; Guo, Jun; Cai, Chunxiao; Zhang, Junxiang; Gao, Jiangrui

    2016-11-15

    Multipartite entanglement is used for quantum information applications, such as building multipartite quantum communications. Generally, generation of multipartite entanglement is based on a complex beam-splitter network. Here, based on the spatial freedom of light, we experimentally demonstrated spatial quadripartite continuous variable entanglement among first-order Hermite-Gaussian modes using a single type II optical parametric oscillator operating below threshold with an HG0245° pump beam. The entanglement can be scalable for larger numbers of spatial modes by changing the spatial profile of the pump beam. In addition, spatial multipartite entanglement will be useful for future spatial multichannel quantum information applications.

  5. Optical Parametric Technology for Methane Measurements

    NASA Technical Reports Server (NTRS)

    Dawsey, Martha; Numata, Kenji; Wu, Stewart; Riris, Haris

    2015-01-01

    Atmospheric methane (CH4) is the second most important anthropogenic greenhouse gas, with approximately 25 times the radiative forcing of carbon dioxide (CO2) per molecule. Yet, lack of understanding of the processes that control CH4 sources and sinks and its potential release from stored carbon reservoirs contributes significant uncertainty to our knowledge of the interaction between carbon cycle and climate change. At Goddard Space Flight Center (GSFC) we have been developing the technology needed to remotely measure CH4 from orbit. Our concept for a CH4 lidar is a nadir viewing instrument that uses the strong laser echoes from the Earth's surface to measure CH4. The instrument uses a tunable, narrow-frequency light source and photon-sensitive detector to make continuous measurements from orbit, in sunlight and darkness, at all latitudes and can be relatively immune to errors introduced by scattering from clouds and aerosols. Our measurement technique uses Integrated Path Differential Absorption (IPDA), which measures the absorption of laser pulses by a trace gas when tuned to a wavelength coincident with an absorption line. We have already demonstrated ground-based and airborne CH4 detection using Optical Parametric Amplifiers (OPA) at 1651 nm using a laser with approximately 10 microJ/pulse at 5kHz with a narrow linewidth. Next, we will upgrade our OPO system to add several more wavelengths in preparation for our September 2015 airborne campaign, and expect that these upgrades will enable CH4 measurements with 1% precision (10-20 ppb).

  6. 650-nJ pulses from a cavity-dumped Yb:fiber-pumped ultrafast optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Lamour, Tobias P.; Reid, Derryck T.

    2011-08-01

    Sub-250-fs pulses with energies of up to 650 nJ and peak powers up to 2.07 MW were generated from a cavity-dumped optical parametric oscillator, synchronously-pumped at 15.3 MHz with sub-400-fs pulses from an Yb:fiber laser. The average beam quality factor of the dumped output was M2 ~1.2 and the total relative-intensity noise was 8 mdBc, making the system a promising candidate for ultrafast laser inscription of infrared materials.

  7. Frequency comb generation by a continuous-wave-pumped optical parametric oscillator based on cascading quadratic nonlinearities.

    PubMed

    Ulvila, Ville; Phillips, C R; Halonen, Lauri; Vainio, Markku

    2013-11-01

    We report optical frequency comb generation by a continuous-wave pumped optical parametric oscillator (OPO) without any active modulation. The OPO is configured as singly resonant with an additional nonlinear crystal (periodically poled MgO:LiNbO3) placed inside the OPO for phase mismatched second harmonic generation (SHG) of the resonating signal beam. The phase mismatched SHG causes cascading χ(2) nonlinearities, which can substantially increase the effective χ(3) nonlinearity in MgO:LiNbO3, leading to spectral broadening of the OPO signal beam via self-phase modulation. The OPO generates a stable 4 THz wide (-30 dB) frequency comb centered at 1.56 μm.

  8. Multicast Parametric Synchronous Sampling

    DTIC Science & Technology

    2011-09-01

    enhancement in a parametric mixer device. Fig. 4 shows the principle of generating uniform, high quality replicas extending over previously un-attainable...critical part of the MPASS architecture and is responsible for the direct and continuous acquisition of data across all of the multicast signal copies...ii) ability to copy THz signals with impunity to tens of replicas ; (iii) all-optical delays > 1.9 us; (iv) 10’s of THz-fast all-optical sampling of

  9. Mid-infrared wavelength- and frequency-modulation spectroscopy with a pump-modulated singly-resonant optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Lindsay, I. D.; Groß, P.; Lee, C. J.; Adhimoolam, B.; Boller, K.-J.

    2006-12-01

    We describe the implementation of the wavelength- and frequency-modulation spectroscopy techniques using a singly-resonant optical parametric oscillator (OPO) pumped by a fiber-amplified diode laser. Frequency modulation of the diode laser was transferred to the OPO’s mid-infrared idler output, avoiding the need for external modulation devices. This approach thus provides a means of implementing these important techniques with powerful, widely tunable, mid-infrared sources while retaining the simple, flexible modulation properties of diode lasers.

  10. High-power, continuous-wave, tunable mid-IR, higher-order vortex beam optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Aadhi, A.; Sharma, Varun; Samanta, G. K.

    2018-05-01

    We report on a novel experimental scheme to generate continuous-wave (cw), high power, and higher-order optical vortices tunable across mid-IR wavelength range. Using cw, two-crystal, singly resonant optical parametric oscillator (T-SRO) and pumping one of the crystals with Gaussian beam and the other crystal with optical vortices of orders, lp = 1 to 6, we have directly transferred the vortices at near-IR to the mid-IR wavelength range. The idler vortices of orders, li = 1 to 6, are tunable across 2276-3576 nm with a maximum output power of 6.8 W at order of, li = 1, for the pump power of 25 W corresponding to a near-IR vortex to mid-IR vortex conversion efficiency as high as 27.2%. Unlike the SROs generating optical vortices restricted to lower orders due to the elevated operation threshold with pump vortex orders, here, the coherent energy coupling between the resonant signals of the crystals of T-SRO facilitates the transfer of pump vortex of any order to the idler wavelength without stringent operation threshold condition. The generic experimental scheme can be used in any wavelength range across the electromagnetic spectrum and in all time scales from cw to ultrafast regime.

  11. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

    PubMed

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

    2014-07-28

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

  12. 93% pump depletion, 3.5-W continuous-wave, singly resonant optical parametric oscillator.

    PubMed

    Bosenberg, W R; Drobshoff, A; Alexander, J I; Myers, L E; Byer, R L

    1996-09-01

    We report two cw, singly resonant optical parametric oscillator (OPO) configurations based on periodically poled lithium niobate that result in significantly higher efficiency and output power than in previous studies. Using four-mirror OPO cavities and pumping with a 1.064-microm Nd:YAG laser, we observe 93% pump depletion and obtain ~86% of the converted pump photons as useful idler output. The single-beam, in-the-bucket idler output power of 3.55 W at 3.25 microm corresponds to ~80% of quantum-limited performance. We measure and compare the amplitude noise and spectral bandwidth of the two configurations. We also demonstrate >1 W of tunable cw output over the 3.3-3.9-microm spectral range.

  13. Femtosecond optical parametric oscillators toward real-time dual-comb spectroscopy

    NASA Astrophysics Data System (ADS)

    Jin, Yuwei; Cristescu, Simona M.; Harren, Frans J. M.; Mandon, Julien

    2015-04-01

    We demonstrate mid-infrared dual-comb spectroscopy with an optical parametric oscillator (OPO) toward real-time field measurement. A singly resonant OPO based on a MgO-doped periodically poled lithium niobate (PPLN) crystal is demonstrated. Chirped mirrors are used to compensate the dispersion caused by the optical cavity and the crystal. A low threshold of 17 mW has been achieved. The OPO source generates a tunable idler frequency comb between 2.7 and 4.7 μm. Dual-comb spectroscopy is achieved by coupling two identical Yb-fiber mode-locked lasers to this OPO with slightly different repetition frequencies. A measured absorption spectrum of methane is presented with a spectral bandwidth of , giving an instrumental resolution of . In addition, a second OPO containing two MgO-doped PPLN crystals in a singly resonant ring cavity is demonstrated. As such, this OPO generates two idler combs (average power up to 220 mW), covering a wavelength range between 2.7 and 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyned signal between the two idler combs, broadband spectra of molecular gases can be observed over a spectral bandwidth of more than . This special cavity design allows the spectral resolution to be improved to without locking the OPO cavity, indicating that this OPO represents an ideal high-power broadband mid-infrared source for real-time gas sensing.

  14. First Demonstration of Electrostatic Damping of Parametric Instability at Advanced LIGO

    NASA Astrophysics Data System (ADS)

    Blair, Carl; Gras, Slawek; Abbott, Richard; Aston, Stuart; Betzwieser, Joseph; Blair, David; DeRosa, Ryan; Evans, Matthew; Frolov, Valera; Fritschel, Peter; Grote, Hartmut; Hardwick, Terra; Liu, Jian; Lormand, Marc; Miller, John; Mullavey, Adam; O'Reilly, Brian; Zhao, Chunnong; Abbott, B. P.; Abbott, T. D.; Adams, C.; Adhikari, R. X.; Anderson, S. B.; Ananyeva, A.; Appert, S.; Arai, K.; Ballmer, S. W.; Barker, D.; Barr, B.; Barsotti, L.; Bartlett, J.; Bartos, I.; Batch, J. C.; Bell, A. S.; Billingsley, G.; Birch, J.; Biscans, S.; Biwer, C.; Bork, R.; Brooks, A. F.; Ciani, G.; Clara, F.; Countryman, S. T.; Cowart, M. J.; Coyne, D. C.; Cumming, A.; Cunningham, L.; Danzmann, K.; Da Silva Costa, C. F.; Daw, E. J.; DeBra, D.; DeSalvo, R.; Dooley, K. L.; Doravari, S.; Driggers, J. C.; Dwyer, S. E.; Effler, A.; Etzel, T.; Evans, T. M.; Factourovich, M.; Fair, H.; Fernández Galiana, A.; Fisher, R. P.; Fulda, P.; Fyffe, M.; Giaime, J. A.; Giardina, K. D.; Goetz, E.; Goetz, R.; Gray, C.; Gushwa, K. E.; Gustafson, E. K.; Gustafson, R.; Hall, E. D.; Hammond, G.; Hanks, J.; Hanson, J.; Harry, G. M.; Heintze, M. C.; Heptonstall, A. W.; Hough, J.; Izumi, K.; Jones, R.; Kandhasamy, S.; Karki, S.; Kasprzack, M.; Kaufer, S.; Kawabe, K.; Kijbunchoo, N.; King, E. J.; King, P. J.; Kissel, J. S.; Korth, W. Z.; Kuehn, G.; Landry, M.; Lantz, B.; Lockerbie, N. A.; Lundgren, A. P.; MacInnis, M.; Macleod, D. M.; Márka, S.; Márka, Z.; Markosyan, A. S.; Maros, E.; Martin, I. W.; Martynov, D. V.; Mason, K.; Massinger, T. J.; Matichard, F.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McCormick, S.; McIntyre, G.; McIver, J.; Mendell, G.; Merilh, E. L.; Meyers, P. M.; Mittleman, R.; Moreno, G.; Mueller, G.; Munch, J.; Nuttall, L. K.; Oberling, J.; Oppermann, P.; Oram, Richard J.; Ottaway, D. J.; Overmier, H.; Palamos, J. R.; Paris, H. R.; Parker, W.; Pele, A.; Penn, S.; Phelps, M.; Pierro, V.; Pinto, I.; Principe, M.; Prokhorov, L. G.; Puncken, O.; Quetschke, V.; Quintero, E. A.; Raab, F. J.; Radkins, H.; Raffai, P.; Reid, S.; Reitze, D. H.; Robertson, N. A.; Rollins, J. G.; Roma, V. J.; Romie, J. H.; Rowan, S.; Ryan, K.; Sadecki, T.; Sanchez, E. J.; Sandberg, V.; Savage, R. L.; Schofield, R. M. S.; Sellers, D.; Shaddock, D. A.; Shaffer, T. J.; Shapiro, B.; Shawhan, P.; Shoemaker, D. H.; Sigg, D.; Slagmolen, B. J. J.; Smith, B.; Smith, J. R.; Sorazu, B.; Staley, A.; Strain, K. A.; Tanner, D. B.; Taylor, R.; Thomas, M.; Thomas, P.; Thorne, K. A.; Thrane, E.; Torrie, C. I.; Traylor, G.; Vajente, G.; Valdes, G.; van Veggel, A. A.; Vecchio, A.; Veitch, P. J.; Venkateswara, K.; Vo, T.; Vorvick, C.; Walker, M.; Ward, R. L.; Warner, J.; Weaver, B.; Weiss, R.; Weßels, P.; Willke, B.; Wipf, C. C.; Worden, J.; Wu, G.; Yamamoto, H.; Yancey, C. C.; Yu, Hang; Yu, Haocun; Zhang, L.; Zucker, M. E.; Zweizig, J.; LSC Instrument Authors

    2017-04-01

    Interferometric gravitational wave detectors operate with high optical power in their arms in order to achieve high shot-noise limited strain sensitivity. A significant limitation to increasing the optical power is the phenomenon of three-mode parametric instabilities, in which the laser field in the arm cavities is scattered into higher-order optical modes by acoustic modes of the cavity mirrors. The optical modes can further drive the acoustic modes via radiation pressure, potentially producing an exponential buildup. One proposed technique to stabilize parametric instability is active damping of acoustic modes. We report here the first demonstration of damping a parametrically unstable mode using active feedback forces on the cavity mirror. A 15 538 Hz mode that grew exponentially with a time constant of 182 sec was damped using electrostatic actuation, with a resulting decay time constant of 23 sec. An average control force of 0.03 nN was required to maintain the acoustic mode at its minimum amplitude.

  15. High-energy infrared femtosecond pulses generated by dual-chirped optical parametric amplification.

    PubMed

    Fu, Yuxi; Takahashi, Eiji J; Midorikawa, Katsumi

    2015-11-01

    We demonstrate high-energy infrared femtosecond pulse generation by a dual-chirped optical parametric amplification (DC-OPA) scheme [Opt. Express19, 7190 (2011)]. By employing a 100 mJ pump laser, a signal pulse energy exceeding 20 mJ at a wavelength of 1.4 μm was achieved before dispersion compensation. A total output energy of 33 mJ was recorded. Under a further energy scaling condition, the signal pulse was compressed to an almost transform-limited duration of 27 fs using a fused silica prism compressor. Since the DC-OPA scheme is efficient and energy scalable, design parameters for obtaining 100 mJ level infrared pulses are presented, which are suitable as driver lasers for the energy scaling of high-order harmonic generation with sub-keV photon energy.

  16. Characteristics of optical parametric oscillator synchronously pumped by Yb:KGW laser and based on periodically poled potassium titanyl phosphate crystal

    NASA Astrophysics Data System (ADS)

    Vengelis, Julius; Tumas, Adomas; Pipinytė, Ieva; Kuliešaitė, Miglė; Tamulienė, Viktorija; Jarutis, Vygandas; Grigonis, Rimantas; Sirutkaitis, Valdas

    2018-03-01

    We present experimental data and numerical simulation results obtained during investigation of synchronously pumped optical parametric oscillator (SPOPO) pumped by femtosecond Yb:KGW laser (central wavelength at 1033 nm). The nonlinear medium for parametric generation was periodically poled potassium titanyl phosphate crystal (PPKTP). Maximum parametric light conversion efficiency from pump power to signal power was more than 37.5% at λs=1530 nm wavelength, whereas the achieved signal wave continuous tuning range was from 1470 nm to 1970 nm with signal pulse durations ranging from 91 fs to roughly 280 fs. We demonstrated wavelength tuning by changing cavity length and PPKTP crystal grating period and also discussed net cavity group delay dispersion (GDD) influence on SPOPO output radiation characteristics. The achieved high pump to signal conversion efficiency and easy wavelength tuning make this device a very promising alternative to Ti:sapphire based SPOPOs as a source of continuously tunable femtosecond laser radiation in the near and mid-IR range.

  17. Parametric amplification in MoS2 drum resonator.

    PubMed

    Prasad, Parmeshwar; Arora, Nishta; Naik, A K

    2017-11-30

    Parametric amplification is widely used in diverse areas from optics to electronic circuits to enhance low level signals by varying relevant system parameters. Parametric amplification has also been performed in several micro-nano resonators including nano-electromechanical system (NEMS) resonators based on a two-dimensional (2D) material. Here, we report the enhancement of mechanical response in a MoS 2 drum resonator using degenerate parametric amplification. We use parametric pumping to modulate the spring constant of the MoS 2 resonator and achieve a 10 dB amplitude gain. We also demonstrate quality factor enhancement in the resonator with parametric amplification. We investigate the effect of cubic nonlinearity on parametric amplification and show that it limits the gain of the mechanical resonator. Amplifying ultra-small displacements at room temperature and understanding the limitations of the amplification in these devices is key for using these devices for practical applications.

  18. Ultrafast optical transistor and router of multi-order fluorescence and spontaneous parametric four-wave mixing in Pr³⁺:YSO.

    PubMed

    Wen, Feng; Ali, Imran; Hasan, Abdulkhaleq; Li, Changbiao; Tang, Haijun; Zhang, Yufei; Zhang, Yanpeng

    2015-10-15

    We study the realization of an optical transistor (switch and amplifier) and router in multi-order fluorescence (FL) and spontaneous parametric four-wave mixing (SP-FWM). We estimate that the switching speed is about 15 ns. The router action results from the Autler-Townes splitting in spectral or time domain. The switch and amplifier are realized by dressing suppression and enhancement in FL and SP-FWM. The optical transistor and router can be controlled by multi-parameters (i.e., power, detuning, or polarization).

  19. High-power Femtosecond Optical Parametric Amplification at 1 kHz in BiB(3)O(6) pumped at 800 nm.

    PubMed

    Petrov, Valentin; Noack, Frank; Tzankov, Pancho; Ghotbi, Masood; Ebrahim-Zadeh, Majid; Nikolov, Ivailo; Buchvarov, Ivan

    2007-01-22

    Substantial power scaling of a travelling-wave femtosecond optical parametric amplifier, pumped near 800 nm by a 1 kHz Ti:sapphire laser amplifier, is demonstrated using monoclinic BiB(3)O(6) in a two stage scheme with continuum seeding. Total energy output (signal plus idler) exceeding 1 mJ is achieved, corresponding to an intrinsic conversion efficiency of approximately 32% for the second stage. The tunability extends from 1.1 to 2.9 microm. The high parametric gain and broad amplification bandwidth of this crystal allowed the maintenance of the pump pulse duration, leading to pulse lengths less than 140 fs, both for the signal and idler pulses, even at such high output levels.

  20. CW seeded optical parametric amplifier providing wavelength and pulse duration tunable nearly transform limited pulses.

    PubMed

    Hädrich, S; Gottschall, T; Rothhardt, J; Limpert, J; Tünnermann, A

    2010-02-01

    An optical parametric amplifier that delivers nearly transform limited pulses is presented. The center wavelength of these pulses can be tuned between 993 nm and 1070 nm and, at the same time, the pulse duration is varied between 206 fs and 650 fs. At the shortest pulse duration the pulse energy was increased up to 7.2 microJ at 50 kHz repetition rate. Variation of the wavelength is achieved by applying a tunable cw seed while the pulse duration can be varied via altering the pump pulse duration. This scheme offers superior flexibility and scaling possibilities.

  1. Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

    2018-06-01

    A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

  2. Flat and ultra-broadband two-pump fiber optical parametric amplifiers based on photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Cao, Nan; Zhu, Hongna; Li, Peipei; Taccheo, Stefano; Zhu, Yuanna; Gao, Xiaorong; Wang, Zeyong

    2018-03-01

    A two-pump fiber optical parametric amplifier (FOPA) based on the photonic crystal fiber (PCF) in the telecommunication region is investigated numerically. The fiber loss and pump depletion are considered. The influences of the fiber length, input signal power, input pump power, and the center pump wavelength on the gain bandwidth, flatness, and peak gain are discussed. The 6-wave model-based analysis of two-pump FOPA is also achieved and compared with that based on the 4-wave model; furthermore, the gain properties of the FOPA based on the 6-wave model are optimized and investigated. The comparison results show that the PCF-based two-pump FOPA achieves flatter and wider gain spectra with less fiber length and input pump power compared to the two-pump FOPA based on the normal highly nonlinear fiber, where the obtained results show the great potential of the FOPA for the optical communication system.

  3. OPO performance with a long pulse length, single frequency Nd:YAG laser pump. [Optical Parametric Oscillators

    NASA Technical Reports Server (NTRS)

    Kozlovsky, W. J.; Gustafson, E. K.; Eckardt, R. C.; Byer, R. L.

    1988-01-01

    With the advent of new nonlinear materials and single-frequency pump sources, there is renewed interest in optical parametric oscillators (OPOs). A single-mode diode-laser-pumped monolithic Nd:YAG nonplanar ring laser that is both amplified and frequency doubled is used to pump a monolithic MgO:LiNbO3 pulsed singly resonant OPO. The OPO signal output was temperature tuned from 834 to 958 nm, producing an idler tuning from 1.47 to 1.2 microns. Efforts toward a CW all-solid-state doubly resonant OPO are also described.

  4. Parametric spectro-temporal analyzer (PASTA) for ultrafast optical performance monitoring

    NASA Astrophysics Data System (ADS)

    Zhang, Chi; Wong, Kenneth K. Y.

    2013-12-01

    Ultrafast optical spectrum monitoring is one of the most challenging tasks in observing ultrafast phenomena, such as the spectroscopy, dynamic observation of the laser cavity, and spectral encoded imaging systems. However, conventional method such as optical spectrum analyzer (OSA) spatially disperses the spectrum, but the space-to-time mapping is realized by mechanical rotation of a grating, so are incapable of operating at high speed. Besides the spatial dispersion, temporal dispersion provided by dispersive fiber can also stretches the spectrum in time domain in an ultrafast manner, but is primarily confined in measuring short pulses. In view of these constraints, here we present a real-time spectrum analyzer called parametric spectro-temporal analyzer (PASTA), which is based on the time-lens focusing mechanism. It achieves a 100-MHz frame rate and can measure arbitrary waveforms. For the first time, we observe the dynamic spectrum of an ultrafast swept-source: Fourier domain mode-locked (FDML) laser, and the spectrum evolution of a laser cavity during its stabilizing process. In addition to the basic single-lens structure, the multi-lens configurations (e.g. telescope or wide-angle scope) will provide a versatile operating condition, which can zoom in to achieve 0.05-nm resolution and zoom out to achieve 10-nm observation range, namely 17 times zoom in/out ratio. In view of the goal of achieving spectrum analysis with fine accuracy, PASTA provides a promising path to study the real-time spectrum of some dynamic phenomena and non-repetitive events, with orders of magnitude enhancement in the frame rate over conventional OSAs.

  5. Influence of the pump threshold on the single-frequency output power of singly resonant optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Sowade, R.; Breunig, I.; Kiessling, J.; Buse, K.

    2009-07-01

    We demonstrate that for a given pump source, there is an optimum pump threshold to achieve the maximum single-frequency output power in singly resonant optical parametric oscillators. Therefore, cavity losses and parametric amplification have to be adjusted. In particular, continuous-wave output powers of 1.5 W were achieved with a 2.5 cm lithium niobate crystal in comparison with 0.5 W by a 5 cm long crystal within the same cavity design. This counter-intuitive result of weaker amplification leading to larger powers can be explained using a model from L.B. Kreuzer (Proc. Joint Conf. Lasers and Opt.-Elect., p. 52, 1969). Kreuzer also states that single-mode operation is possible only up to pump powers which are 4.6 times the threshold value. Additionally, implementing an outcoupling mirror to increase losses, single-frequency waves with powers of 3 W at 3.2 µm and 7 W at 1.5 µm could be generated simultaneously.

  6. Ground and Airborne Methane Measurements using Optical Parametric Amplifiers

    NASA Technical Reports Server (NTRS)

    Riris, Haris; Numata, Kenji; Li, Steve; Wu, Stewart; Kawa, Stephan R.; Abshire, James; Dawsey, Martha; Ramanathan, Anand

    2012-01-01

    We report on an initial airborne demonstration of atmospheric methane column measurements at 1.65 micrometers using a widely tunable, seeded optical parametric amplifier (OPA) lidar and a photon counting detector. Methane is an important greenhouse gas and accurate knowledge of its sources and sinks is needed for climate modeling. Our lidar system uses 20 pulses at increasing wavelengths and integrated path differential absorption (IPDA) to map a methane line at 1650.9 nanometers. The wavelengths are generated by using a Nd:YAG pump laser at 1064.5 nanometers and distributed feedback diode laser at 1650.9 nanometers and a periodically-poled lithium niobate (PPLN) crystal. The pulse width was 3 nanoseconds and the pulse repetition rate was 6.28 KHz. The outgoing energy was approximately 13 microJoules/pulse. A commercial 20 nanometer diameter fiber-coupled telescope with a photon counting detector operated in analog mode with a 0.8 nanometer bandpass filter was used as the lidar receiver. The lidar system was integrated on NASA's DC-8 flying laboratory, based at Dryden Airborne operations Facility (DAOF) in Palmdale CA. Three flights were performed in the central valley of California. Each flight lasted about 2.5 hours and it consisted of several flight segments at constant altitudes at approximately 3, 4.5, 6, 7.6, 9.1, 10.6 km (l0, 15, 20, 25, 30, 35 kft). An in-situ cavity ring down spectrometer made by Picarro Inc. was flown along with the lidar instrument provided us with the "truth" i.e. the local CH4, CO2 and H2O concentrations at the constant flight altitude segments. Using the aircraft's altitude, GPS, and meteorological data we calculated the theoretical differential optical depth of the methane absorption at increasing altitudes. Our results showed good agreement between the experimentally derived optical depth measurements from the lidar instrument and theoretical calculations as the flight altitude was increased from 3 to 10.6 kilometers, assuming a

  7. Time-dependent spatial intensity profiles of near-infrared idler pulses from nanosecond optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Olafsen, L. J.; Olafsen, J. S.; Eaves, I. K.

    2018-06-01

    We report on an experimental investigation of the time-dependent spatial intensity distribution of near-infrared idler pulses from an optical parametric oscillator measured using an infrared (IR) camera, in contrast to beam profiles obtained using traditional knife-edge techniques. Comparisons show the information gained by utilizing the thermal camera provides more detail than the spatially- or time-averaged measurements from a knife-edge profile. Synchronization, averaging, and thresholding techniques are applied to enhance the images acquired. The additional information obtained can improve the process by which semiconductor devices and other IR lasers are characterized for their beam quality and output response and thereby result in IR devices with higher performance.

  8. Fast and wide tuning wavelength-swept source based on dispersion-tuned fiber optical parametric oscillator.

    PubMed

    Zhou, Yue; Cheung, Kim K Y; Li, Qin; Yang, Sigang; Chui, P C; Wong, Kenneth K Y

    2010-07-15

    We demonstrate a dispersion-tuned fiber optical parametric oscillator (FOPO)-based swept source with a sweep rate of 40 kHz and a wavelength tuning range of 109 nm around 1550 nm. The cumulative speed exceeds 4,000,000 nm/s. The FOPO is pumped by a sinusoidally modulated pump, which is driven by a clock sweeping linearly from 1 to 1.0006 GHz. A spool of dispersion-compensating fiber is added inside the cavity to perform dispersion tuning. The instantaneous linewidth is 0.8 nm without the use of any wavelength selective element inside the cavity. 1 GHz pulses with pulse width of 150 ps are generated.

  9. Network of time-multiplexed optical parametric oscillators as a coherent Ising machine

    NASA Astrophysics Data System (ADS)

    Marandi, Alireza; Wang, Zhe; Takata, Kenta; Byer, Robert L.; Yamamoto, Yoshihisa

    2014-12-01

    Finding the ground states of the Ising Hamiltonian maps to various combinatorial optimization problems in biology, medicine, wireless communications, artificial intelligence and social network. So far, no efficient classical and quantum algorithm is known for these problems and intensive research is focused on creating physical systems—Ising machines—capable of finding the absolute or approximate ground states of the Ising Hamiltonian. Here, we report an Ising machine using a network of degenerate optical parametric oscillators (OPOs). Spins are represented with above-threshold binary phases of the OPOs and the Ising couplings are realized by mutual injections. The network is implemented in a single OPO ring cavity with multiple trains of femtosecond pulses and configurable mutual couplings, and operates at room temperature. We programmed a small non-deterministic polynomial time-hard problem on a 4-OPO Ising machine and in 1,000 runs no computational error was detected.

  10. Parametric amplification of a superconducting plasma wave

    DOE PAGES

    Rajasekaran, S.; Casandruc, E.; Laplace, Y.; ...

    2016-07-11

    Many applications in photonics require all-optical manipulation of plasma waves, which can concentrate electromagnetic energy on sub-wavelength length scales. This is difficult in metallic plasmas because of their small optical nonlinearities. Some layered superconductors support Josephson plasma waves, involving oscillatory tunnelling of the superfluid between capacitively coupled planes. Josephson plasma waves are also highly nonlinear, and exhibit striking phenomena such as cooperative emission of coherent terahertz radiation, superconductor–metal oscillations and soliton formation. In this paper, we show that terahertz Josephson plasma waves can be parametrically amplified through the cubic tunnelling nonlinearity in a cuprate superconductor. Finally, parametric amplification is sensitivemore » to the relative phase between pump and seed waves, and may be optimized to achieve squeezing of the order-parameter phase fluctuations or terahertz single-photon devices.« less

  11. Active locking and entanglement in type II optical parametric oscillators

    NASA Astrophysics Data System (ADS)

    Ruiz-Rivas, Joaquín; de Valcárcel, Germán J.; Navarrete-Benlloch, Carlos

    2018-02-01

    Type II optical parametric oscillators are amongst the highest-quality sources of quantum-correlated light. In particular, when pumped above threshold, such devices generate a pair of bright orthogonally-polarized beams with strong continuous-variable entanglement. However, these sources are of limited practical use, because the entangled beams emerge with different frequencies and a diffusing phase difference. It has been proven that the use of an internal wave-plate coupling the modes with orthogonal polarization is capable of locking the frequencies of the emerging beams to half the pump frequency, as well as reducing the phase-difference diffusion, at the expense of reducing the entanglement levels. In this work we characterize theoretically an alternative locking mechanism: the injection of a laser at half the pump frequency. Apart from being less invasive, this method should allow for an easier real-time experimental control. We show that such an injection is capable of generating the desired phase locking between the emerging beams, while still allowing for large levels of entanglement. Moreover, we find an additional region of the parameter space (at relatively large injections) where a mode with well defined polarization is in a highly amplitude-squeezed state.

  12. Theory and Simulation of Gain-Guided Noncollinear Modes in Chirped Quasi-Phase-Matched Optical Parametric Amplifiers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, Martin

    Chirped quasi-phase-matched (QPM) gratings offer essentially constant gain over wide bandwidths, making them promising candidates for short-pulse optical parametric amplifiers. However, experiments have shown that high-gain non-collinear processes exist in spite of the dephasing caused by the non-uniformity of the QPM grating and compete with the desired collinear broadband gain of the amplifier. In this paper, these non-collinear gain-guided modes are investigated numerically and analytically in a model that includes longitudinal non-uniformity of the phase-matching profile, lateral localization of the pump beam and non-collinear propagation of the interacting waves.

  13. Laser-induced fluorescence microscopic system using an optical parametric oscillator for tunable detection in microchip analysis.

    PubMed

    Kumemura, Momoko; Odake, Tamao; Korenaga, Takashi

    2005-06-01

    A laser-induced fluorescence microscopic system based on optical parametric oscillation has been constructed as a tunable detector for microchip analysis. The detection limit of sulforhodamine B (Ex. 520 nm, Em. 570 nm) was 0.2 mumol, which was approximately eight orders of magnitude better than with a conventional fluorophotometer. The system was applied to the determination of fluorescence-labeled DNA (Ex. 494 nm, Em. 519 nm) in a microchannel and the detection limit reached a single molecule. These results showed the feasibility of this system as a highly sensitive and tunable fluorescence detector for microchip analysis.

  14. Measurement of IR optics with linear coupling's action-angle parametrization

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Bai, M.; Pilat, F.; Satogata, T.; Trbojevic, D.

    2005-08-01

    Linear coupling’s action-angle parametrization is convenient for interpretation of turn-by-turn beam position monitor (BPM) data. We demonstrate how to apply this parametrization to extract Twiss and coupling parameters in interaction regions (IRs), using BPMs on each side of a long IR drift region. Example data were acquired at the Relativistic Heavy Ion Collider, using an ac dipole to excite a single transverse eigenmode. We have measured the waist of the β function and its Twiss and coupling parameters.

  15. NONLINEAR OPTICAL EFFECTS AND FIBER OPTICS: Use of an open resonator in a parametric free-electron laser

    NASA Astrophysics Data System (ADS)

    Alekseev, V. I.; Bessonov, Evgenii G.; Serov, Alexander V.

    1988-12-01

    Parametric free-electron lasers utilizing open resonators and beams consisting of a series of identical particle bunches are analyzed theoretically. It is shown that the use of a resonator in a parametric laser system can increase the radiation intensity and its monochromaticity.

  16. Entanglement-seeded, dual, optical parametric amplification: Applications to quantum imaging and metrology

    NASA Astrophysics Data System (ADS)

    Glasser, Ryan T.; Cable, Hugo; Dowling, Jonathan P.; de Martini, Francesco; Sciarrino, Fabio; Vitelli, Chiara

    2008-07-01

    The study of optical parametric amplifiers (OPAs) has been successful in describing and creating nonclassical light for use in fields such as quantum metrology and quantum lithography [Agarwal , J. Opt. Soc. Am. B 24, 2 (2007)]. In this paper we present the theory of an OPA scheme utilizing an entangled state input. The scheme involves two identical OPAs seeded with the maximally path-entangled ∣N00N⟩ state (∣2,0⟩+∣0,2⟩)/2 . The stimulated amplification results in output state probability amplitudes that have a dependence on the number of photons in each mode, which differs greatly from two-mode squeezed vacuum. A large family of entangled output states are found. Specific output states allow for the heralded creation of N=4 N00N states, which may be used for quantum lithography, to write sub-Rayleigh fringe patterns, and for quantum interferometry, to achieve Heisenberg-limited phase measurement sensitivity.

  17. Multi-dressing suppression and enhancement and all-optical switching in parametrically amplified four-wave mixing

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; Zhang, Dan; Sun, Ming; Li, Kangkang; Wang, Zhiguo; Zhang, Yanpeng

    2018-04-01

    We study different dressing effects in parametrically amplified four-wave mixing (PA-FWM) processes. By seeding a weak probe laser into the Stokes or anti-Stokes channel of the FWM, the gain process is generated in the so-called bright twin beams which are the probe and conjugate beams. The dressing types dramatically affect the gain factors in both the probe and conjugate channels. The gain factor of the FWM signal decreases under the cascade-type dressing and the signal's shape splits into two dips under this dressing type. However, the intensity of the FWM signal changes from suppression to enhancement under the parallel-type dressing. We will apply this switching process to all-optical switching.

  18. Parametrization of optical properties of indium-tin-oxide thin films by spectroscopic ellipsometry: Substrate interfacial reactivity

    NASA Astrophysics Data System (ADS)

    Losurdo, M.; Giangregorio, M.; Capezzuto, P.; Bruno, G.; de Rosa, R.; Roca, F.; Summonte, C.; Plá, J.; Rizzoli, R.

    2002-01-01

    Indium-tin-oxide (ITO) films deposited by sputtering and e-gun evaporation on both transparent (Corning glass) and opaque (c-Si, c-Si/SiO2) substrates and in c-Si/a-Si:H/ITO heterostructures have been analyzed by spectroscopic ellipsometry (SE) in the range 1.5-5.0 eV. Taking the SE advantage of being applicable to absorbent substrate, ellipsometry is used to determine the spectra of the refractive index and extinction coefficient of the ITO films. The effect of the substrate surface on the ITO optical properties is focused and discussed. To this aim, a parametrized equation combining the Drude model, which considers the free-carrier response at the infrared end, and a double Lorentzian oscillator, which takes into account the interband transition contribution at the UV end, is used to model the ITO optical properties in the useful UV-visible range, whatever the substrate and deposition technique. Ellipsometric analysis is corroborated by sheet resistance measurements.

  19. A novel structure photonic crystal fiber based on bismuth-oxide for optical parametric amplification

    NASA Astrophysics Data System (ADS)

    Jin, Cang; Yuan, Jinhui; Yu, Chongxiu

    2010-11-01

    The heavy metal oxide glasses containing bismuth such as bismuth sesquioxide show unique high refractive index. In addition, the bismuth-oxide based glass does not include toxic elements such as Pb, As, Se, Te, and exhibits well chemical, mechanical and thermal stability. Hence, it is used to fabricate high nonlinear fiber for nonlinear optical application. Although the bismuth-oxide based high nonlinear fiber can be fusion-spliced to conventional silica fibers and have above advantages, yet it suffers from large group velocity dispersion because of material chromatic dispersion which restricts its utility. In regard to this, the micro-structure was introduced to adjust the dispersion of bismuth-oxide high nonlinear fiber in the 1550nm wave-band. In this paper, a hexagonal solid-core micro-structure is developed to balance its dispersion and nonlinearity. Our simulation and calculation results show that the bismuth-oxide based photonic crystal fiber has near zero dispersion around 1550nm where the optical parametric amplification suitable wavelength is. Its dispersion slop in the communication wavelength range is also relatively flat. Moreover, both nonlinear coefficient and model filed distribution were simulated, respectively.

  20. Investigation on phase noise of the signal from a singly resonant optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Jinxia, Feng; Yuanji, Li; Kuanshou, Zhang

    2018-04-01

    The phase noise of the signal from a singly resonant optical parametric oscillator (SRO) is investigated theoretically and experimentally. An SRO based on periodically poled lithium niobate is built up that generates the signal with a maximum power of 5.2 W at 1.5 µm. The intensity noise of the signal reaches the shot noise level for frequencies above 5 MHz. The phase noise of the signal oscillates depending on the analysis frequency, and there are phase noise peaks above the shot noise level at the peak frequencies. To explain the phase noise feature of the signal, a semi-classical theoretical model of SROs including the guided acoustic wave Brillouin scattering effect within the nonlinear crystal is developed. The theoretical predictions are in good agreement with the experimental results.

  1. Cavity-dumped femtosecond optical parametric oscillator based on periodically poled stoichiometric lithium tantalate

    NASA Astrophysics Data System (ADS)

    Yoon, E.; Joo, T.

    2016-03-01

    A synchronously pumped cavity-dumped femtosecond optical parametric oscillator (OPO) based on a periodically poled stoichiometric lithium tantalate (PPSLT) crystal is reported. The OPO runs in positive group velocity dispersion (GVD) mode to deliver high pulse energy at high repetition rate. It delivers pulse energy over 130 nJ up to 500 kHz and 70 nJ at 1 MHz of repetition rate at 1100 nm. Pulse duration is as short as 42 fs, and the OPO is tunable in the near infrared region from 1050 to 1200 nm. Dispersion property of the OPO was also explored. The cavity-dumped output carries a positive GVD, which can be compensated easily by an external prism pair, and large negative third order dispersion (TOD), which results in a pedestal in the pulse shape. Approaches to obtain clean pulse shape by reducing the large TOD are proposed.

  2. High power tunable mid-infrared optical parametric oscillator enabled by random fiber laser.

    PubMed

    Wu, Hanshuo; Wang, Peng; Song, Jiaxin; Ye, Jun; Xu, Jiangming; Li, Xiao; Zhou, Pu

    2018-03-05

    Random fiber laser, as a kind of novel fiber laser that utilizes random distributed feedback as well as Raman gain, has become a research focus owing to its advantages of wavelength flexibility, modeless property and output stability. Herein, a tunable optical parametric oscillator (OPO) enabled by a random fiber laser is reported for the first time. By exploiting a tunable random fiber laser to pump the OPO, the central wavelength of idler light can be continuously tuned from 3977.34 to 4059.65 nm with stable temporal average output power. The maximal output power achieved is 2.07 W. So far as we know, this is the first demonstration of a continuous-wave tunable OPO pumped by a tunable random fiber laser, which could not only provide a new approach for achieving tunable mid-infrared (MIR) emission, but also extend the application scenarios of random fiber lasers.

  3. Fast, precise, and widely tunable frequency control of an optical parametric oscillator referenced to a frequency comb.

    PubMed

    Prehn, Alexander; Glöckner, Rosa; Rempe, Gerhard; Zeppenfeld, Martin

    2017-03-01

    Optical frequency combs (OFCs) provide a convenient reference for the frequency stabilization of continuous-wave lasers. We demonstrate a frequency control method relying on tracking over a wide range and stabilizing the beat note between the laser and the OFC. The approach combines fast frequency ramps on a millisecond timescale in the entire mode-hop free tuning range of the laser and precise stabilization to single frequencies. We apply it to a commercially available optical parametric oscillator (OPO) and demonstrate tuning over more than 60 GHz with a ramping speed up to 3 GHz/ms. Frequency ramps spanning 15 GHz are performed in less than 10 ms, with the OPO instantly relocked to the OFC after the ramp at any desired frequency. The developed control hardware and software are able to stabilize the OPO to sub-MHz precision and to perform sequences of fast frequency ramps automatically.

  4. Generation and parametric amplification of broadband chirped pulses in the near-infrared

    NASA Astrophysics Data System (ADS)

    Marcinkevičiūtė, A.; Michailovas, K.; Butkus, R.

    2018-05-01

    We demonstrate generation and optical parametric amplification of broadband chirped pulses in the range of 1.8- 2 . 5 μm. The setup is built around Ti:sapphire oscillator as a seed source and 1 kHz Nd:YAG laser system as a pump source. Visible broadband seed pulses are temporally stretched and amplified in a non-collinear optical parametric amplifier before being mixed with fundamental harmonic of the pump laser. Difference frequency generation between positively-chirped broadband pulses centered at 0 . 7 μm and non-chirped narrowband pulses at 1064 nm produces negatively-chirped wide spectral bandwidth pulses in the infrared. After subsequent parametric amplification, pulses with more than 0.5 mJ energy were obtained with spectral bandwidth supporting transform-limited pulse durations as short as 23 fs.

  5. Unity-Efficiency Parametric Down-Conversion via Amplitude Amplification.

    PubMed

    Niu, Murphy Yuezhen; Sanders, Barry C; Wong, Franco N C; Shapiro, Jeffrey H

    2017-03-24

    We propose an optical scheme, employing optical parametric down-converters interlaced with nonlinear sign gates (NSGs), that completely converts an n-photon Fock-state pump to n signal-idler photon pairs when the down-converters' crystal lengths are chosen appropriately. The proof of this assertion relies on amplitude amplification, analogous to that employed in Grover search, applied to the full quantum dynamics of single-mode parametric down-conversion. When we require that all Grover iterations use the same crystal, and account for potential experimental limitations on crystal-length precision, our optimized conversion efficiencies reach unity for 1≤n≤5, after which they decrease monotonically for n values up to 50, which is the upper limit of our numerical dynamics evaluations. Nevertheless, our conversion efficiencies remain higher than those for a conventional (no NSGs) down-converter.

  6. Stimulated Raman scattering in an optical parametric oscillator based on periodically poled MgO-doped stoichiometric LiTaO3.

    PubMed

    My, T-H; Robin, O; Mhibik, O; Drag, C; Bretenaker, F

    2009-03-30

    The evolution of the spectrum of a singly resonant optical parametric oscillator based on an MgO-doped periodically poled stoichiometric lithium tantalate crystal is observed when the pump power is varied. The onset of cascade Raman lasing due to stimulated Raman scattering in the nonlinear crystal is analyzed. Spurious frequency doubling and sum-frequency generation phenomena are observed and understood. A strong reduction of the intracavity Raman scattering is obtained by a careful adjustment of the cavity losses.

  7. Genetically modified rabies virus-vectored Ebola virus disease vaccines are safe and induce efficacious immune responses in mice and dogs.

    PubMed

    Shuai, Lei; Wang, Xijun; Wen, Zhiyuan; Ge, Jinying; Wang, Jinliang; Zhao, Dandan; Bu, Zhigao

    2017-10-01

    Ebola viruses (EBOVs) are zoonotic pathogens that cause EBOV disease (EVD) with high case fatality in humans. Currently, EVD vaccines are still under development in several countries. Here, we generated two recombinant rabies viruses (RABVs), rERAG 333E /ZGP and rERAG 333E /SGP, expressing the Zaire EBOV glycoprotein (ZGP) or Sudan EBOV glycoprotein (SGP) gene based on a modified ERA vaccine strain (rERAG 333E ) vector platform. The recombinant RABVs retained growth properties similar to those of the vector virus in BSR cell culture and efficiently expressed ZGP or SGP. After intracerebral (i.c.) inoculation with rERAG 333E /ZGP or rERAG 333E /SGP, all adult mice showed no signs of disease or weight loss and suckling mice maintained similar survivorship curve as those mice inoculated with control vector rERAG 333E , demonstrating that ZGP or SGP expression did not increase the virulence of the vector. Mouse immunization studies showed that vaccination with rERAG 333E /ZGP and rERAG 333E /SGP induced Zaire or Sudan EBOV neutralizing antibody (VNA) responses and IgG, IgG2a responses to ZGP or SGP, suggesting their potential as oral or inactivated bivalent vaccines against rabies and EVD. Most importantly, all dogs immunized orally with rERAG 333E /ZGP developed long-lasting ZEBOV and RABV VNA responses with or without previous rabies vaccine immunization history. Live rERAG 333E with EBOV GP thus appear to have the potential to be oral vaccines for free-roaming animals in endemic areas of EVD and rabies, and may serve as inactivated vaccines for use in humans. Copyright © 2017. Published by Elsevier B.V.

  8. The usability of the optical parametric amplification of light for high-angular-resolution imaging and fast astrometry

    NASA Astrophysics Data System (ADS)

    Kurek, A. R.; Stachowski, A.; Banaszek, K.; Pollo, A.

    2018-05-01

    High-angular-resolution imaging is crucial for many applications in modern astronomy and astrophysics. The fundamental diffraction limit constrains the resolving power of both ground-based and spaceborne telescopes. The recent idea of a quantum telescope based on the optical parametric amplification (OPA) of light aims to bypass this limit for the imaging of extended sources by an order of magnitude or more. We present an updated scheme of an OPA-based device and a more accurate model of the signal amplification by such a device. The semiclassical model that we present predicts that the noise in such a system will form so-called light speckles as a result of light interference in the optical path. Based on this model, we analysed the efficiency of OPA in increasing the angular resolution of the imaging of extended targets and the precise localization of a distant point source. According to our new model, OPA offers a gain in resolved imaging in comparison to classical optics. For a given time-span, we found that OPA can be more efficient in localizing a single distant point source than classical telescopes.

  9. Two-crystal mid-infrared optical parametric oscillator for absorption and dispersion dual-comb spectroscopy.

    PubMed

    Jin, Yuwei; Cristescu, Simona M; Harren, Frans J M; Mandon, Julien

    2014-06-01

    We present a femtosecond optical parametric oscillator (OPO) containing two magnesium-doped periodically poled lithium niobate crystals in a singly resonant ring cavity, pumped by two mode-locked Yb-fiber lasers. As such, the OPO generates two idler combs (up to 220 mW), covering a wavelength range from 2.7 to 4.2 μm, from which a mid-infrared dual-comb Fourier transform spectrometer is constructed. By detecting the heterodyning signal between the two idler beams a full broadband spectrum of a molecular gas can be observed over 250  cm(-1) within 70 μs with a spectral resolution of 15 GHz. The absorption and dispersion spectra of acetylene and methane have been measured around 3000  cm(-1), indicating that this OPO represents an ideal broadband mid-infrared source for fast chemical sensing.

  10. Nonlinear optical interactions in silicon waveguides

    NASA Astrophysics Data System (ADS)

    Kuyken, B.; Leo, F.; Clemmen, S.; Dave, U.; Van Laer, R.; Ideguchi, T.; Zhao, H.; Liu, X.; Safioui, J.; Coen, S.; Gorza, S. P.; Selvaraja, S. K.; Massar, S.; Osgood, R. M.; Verheyen, P.; Van Campenhout, J.; Baets, R.; Green, W. M. J.; Roelkens, G.

    2017-03-01

    The strong nonlinear response of silicon photonic nanowire waveguides allows for the integration of nonlinear optical functions on a chip. However, the detrimental nonlinear optical absorption in silicon at telecom wavelengths limits the efficiency of many such experiments. In this review, several approaches are proposed and demonstrated to overcome this fundamental issue. By using the proposed methods, we demonstrate amongst others supercontinuum generation, frequency comb generation, a parametric optical amplifier, and a parametric optical oscillator.

  11. Narrowband, tunable, 2 µm optical parametric master-oscillator power amplifier with large-aperture periodically poled Rb:KTP

    NASA Astrophysics Data System (ADS)

    Coetzee, R. S.; Zheng, X.; Fregnani, L.; Laurell, F.; Pasiskevicius, V.

    2018-06-01

    A high-energy, ns, narrow-linewidth optical parametric oscillator and amplifier system based on large-aperture periodically poled Rb:KTP is presented. The 2 µm seed source is a singly resonant OPO locked with a transversely chirped volume Bragg grating, allowing a wavelength tuning of 21 nm and output linewidth of 0.56 nm. A maximum output energy of 52 mJ and conversion efficiency of 36% was obtained from the amplifier for a pump energy of 140 mJ. The high-energy and the robust and narrow dual-wavelength spectra obtained make this system an ideal pump source for difference frequency generation-based THz generation schemes.

  12. Resonant dampers for parametric instabilities in gravitational wave detectors

    NASA Astrophysics Data System (ADS)

    Gras, S.; Fritschel, P.; Barsotti, L.; Evans, M.

    2015-10-01

    Advanced gravitational wave interferometric detectors will operate at their design sensitivity with nearly ˜1 MW of laser power stored in the arm cavities. Such large power may lead to the uncontrolled growth of acoustic modes in the test masses due to the transfer of optical energy to the mechanical modes of the arm cavity mirrors. These parametric instabilities have the potential to significantly compromise the detector performance and control. Here we present the design of "acoustic mode dampers" that use the piezoelectric effect to reduce the coupling of optical to mechanical energy. Experimental measurements carried on an Advanced LIGO-like test mass have shown a tenfold reduction in the amplitude of several mechanical modes, thus suggesting that this technique can greatly mitigate the impact of parametric instabilities in advanced detectors.

  13. Design of a terahertz parametric oscillator based on a resonant cavity in a terahertz waveguide

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Saito, K., E-mail: k-saito@material.tohoku.ac.jp; Oyama, Y.; Tanabe, T.

    We demonstrate ns-pulsed pumping of terahertz (THz) parametric oscillations in a quasi-triply resonant cavity in a THz waveguide. The THz waves, down converted through parametric interactions between the pump and signal waves at telecom frequencies, are confined to a GaP single mode ridge waveguide. By combining the THz waveguide with a quasi-triply resonant cavity, the nonlinear interactions can be enhanced. A low threshold pump intensity for parametric oscillations can be achieved in the cavity waveguide. The THz output power can be maximized by optimizing the quality factors of the cavity so that an optical to THz photon conversion efficiency, η{submore » p}, of 0.35, which is near the quantum-limit level, can be attained. The proposed THz optical parametric oscillator can be utilized as an efficient and monochromatic THz source.« less

  14. An optical parametric chirped-pulse amplifier for seeding high repetition rate free-electron lasers

    DOE PAGES

    Höppner, H.; Hage, A.; Tanikawa, T.; ...

    2015-05-15

    High repetition rate free-electron lasers (FEL), producing highly intense extreme ultraviolet and x-ray pulses, require new high power tunable femtosecond lasers for FEL seeding and FEL pump-probe experiments. A tunable, 112 W (burst mode) optical parametric chirped-pulse amplifier (OPCPA) is demonstrated with center frequencies ranging from 720–900 nm, pulse energies up to 1.12 mJ and a pulse duration of 30 fs at a repetition rate of 100 kHz. Since the power scalability of this OPCPA is limited by the OPCPA-pump amplifier, we also demonstrate a 6.7–13.7 kW (burst mode) thin-disk OPCPA-pump amplifier, increasing the possible OPCPA output power to manymore » hundreds of watts. Furthermore, third and fourth harmonic generation experiments are performed and the results are used to simulate a seeded FEL with high-gain harmonic generation.« less

  15. Conceptual design of sub-exa-watt system by using optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Kawanaka, J.; Tsubakimoto, K.; Yoshida, H.; Fujioka, K.; Fujimoto, Y.; Tokita, S.; Jitsuno, T.; Miyanaga, N.; Gekko-EXA Design Team

    2016-03-01

    A 50 PW ultrahigh-peak-power laser has been conceptually designed, which is based on optical parametric chirped pulse amplification (OPCPA). A 250 J DPSSL and a flash- lamp-pumped kJ laser are adopted as new repeatable pump source. The existed LFEX-laser with more than ten kilo joules are used in the final amplifier stage and the OPCPA with the 2x2 tiled pump beams in random phase has been proposed with several ten centimeter aperture. A pulse duration of amplified pulses is set at less than 10 fs. A broadband OPCPA with ∼500 nm of the gain spectral width near 1 μm is required. A partially deuterated KDP (p-DKDP) crystal is one of the most promising nonlinear crystals and our numerical calculation ensured such ultra-broad gain width. p-DKDP crystals with several deuteration ratio have been successfully grown.

  16. Femtosecond deep-infrared optical parametric oscillator pumped directly by a Ti:sapphire laser

    NASA Astrophysics Data System (ADS)

    O'Donnell, Callum; Chaitanya Kumar, S.; Zawilski, Kevin T.; Schunemann, Peter G.; Ebrahim-Zadeh, Majid

    2018-02-01

    We report a high-repetition-rate femtosecond optical parametric oscillator (OPO) for the deep-infrared (deep-IR) based on the nonlinear optical crystal, CdSiP2 (CSP), pumped directly by a Ti:sapphire laser, for the first time. By pumping CSP at <1 μm, we have achieved practical output powers at the longest wavelengths generated by any Ti:sapphire-pumped OPO. Using a combination of pump wavelength tuning, type-I critical phase-matching, and cavity delay tuning, we have generated continuously tunable radiation across 6654-8373 nm (1194-1503 cm-1) at 80.5 MHz repetition rate, providing up to 20 mW of average power at 7314 nm and <7 mW beyond 8000 nm, with idler spectra exhibiting bandwidths of 140-180 nm across the tuning range. Moreover, the near-IR signal is tunable across 1127-1192 nm, providing up to 37 mW of average power at 1150 nm. Signal pulses, characterised using intensity autocorrelation, have durations of 260-320 fs, with corresponding time-bandwidth product of ΔυΔτ 1. The idler and signal output exhibit a TEM00 spatial profile with single-peak Gaussian distribution. With an equivalent spectral brightness of 6.68×1020 photons s-1 mm-2 sr-1 0.1% BW-1, this OPO represents a viable table-top alternative to synchrotron and supercontinuum sources for deep-IR applications in spectroscopy, metrology and medical diagnostics.

  17. THz-wave parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Kawase, Kodo

    2004-12-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We have also developed a novel basic technology for THz imaging, which allows detection and identification of chemicals by introducing the component spatial pattern analysis. The spatial distributions of the chemicals were obtained from terahertz multispectral trasillumination images, using absorption spectra previously measured with a widely tunable THz-wave parametric oscillator. Further we have applied this technique to the detection and identification of illicit drugs concealed in envelopes. The samples we used were methamphetamine and MDMA, two of the most widely consumed illegal drugs in Japan, and aspirin as a reference.

  18. Beam patterns in an optical parametric oscillator set-up employing walk-off compensating beta barium borate crystals

    NASA Astrophysics Data System (ADS)

    Kaucikas, M.; Warren, M.; Michailovas, A.; Antanavicius, R.; van Thor, J. J.

    2013-02-01

    This paper describes the investigation of an optical parametric oscillator (OPO) set-up based on two beta barium borate (BBO) crystals, where the interplay between the crystal orientations, cut angles and air dispersion substantially influenced the OPO performance, and especially the angular spectrum of the output beam. Theory suggests that if two BBO crystals are used in this type of design, they should be of different cuts. This paper aims to provide an experimental manifestation of this fact. Furthermore, it has been shown that air dispersion produces similar effects and should be taken into account. An x-ray crystallographic indexing of the crystals was performed as an independent test of the above conclusions.

  19. Molecular fingerprint-region spectroscopy from 5 to 12  μm using an orientation-patterned gallium phosphide optical parametric oscillator.

    PubMed

    Maidment, Luke; Schunemann, Peter G; Reid, Derryck T

    2016-09-15

    We report a femtosecond optical parametric oscillator (OPO) based on the new semiconductor gain material orientation-patterned gallium phosphide (OP-GaP), which enables the production of high-repetition-rate femtosecond pulses spanning 5-12 μm with average powers in the few to tens of milliwatts range. This is the first example of a broadband OPO operating across the molecular fingerprint region, and we demonstrate its potential by conducting broadband Fourier-transform spectroscopy using water vapor and a polystyrene reference standard.

  20. Trace Gas Measurements on Mars and Earth Using Optical Parametric Generation

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Haris, Riris; Li, Steve; Sun, Xiaoli; Abshire, James Brice

    2010-01-01

    Trace gases and their isotopic ratios in planetary atmospheres offer important but subtle clues as to the origins of a planet's atmosphere, hydrology, geology, and potential for biology. An orbiting laser remote sensing instrument is capable of measuring trace gases on a global scale with unprecedented accuracy, and higher spatial resolution that can be obtained by passive instruments. We have developed an active sensing instrument for the remote measurement of trace gases in planetary atmospheres (including Earth). The technique uses widely tunable, seeded optical parametric generation (OPG) to measure methane, CO2, water vapor, and other trace gases in the near and mid-infrared spectral regions. Methane is a strong greenhouse gas on Earth and it is also a potential biogenic marker on Mars and other planets. Methane in the Earth's atmosphere survives for a shorter time than CO2 but its impact on climate change can be larger than CO2. Methane levels have remained relatively constant over the last decade around 1.78 parts per million (ppm) but recent observations indicate that methane levels may be on the rise. Increasing methane concentrations may trigger a positive feedback loop and a subsequent runaway greenhouse effect, where increasing temperatures result in increasing methane levels. The NRC Decadal Survey recognized the importance of global observations of greenhouse gases and called for simultaneous CH4, CO, and CO2 measurements but also underlined the technological limitations for these observations. For Mars, methane measurements are of great interest because of its potential as a strong biogenic marker. A remote sensing instrument that can measure day and night over all seasons and latitudes can identify and localize sources of biogenic gas plumes produced by subsurface chemistry or biology, and aid in the search for extra-terrestrial life. It can identify the dynamics of methane generation over time and latitude and identify future lander mission sites

  1. Pixel-based parametric source depth map for Cerenkov luminescence imaging

    NASA Astrophysics Data System (ADS)

    Altabella, L.; Boschi, F.; Spinelli, A. E.

    2016-01-01

    Optical tomography represents a challenging problem in optical imaging because of the intrinsically ill-posed inverse problem due to photon diffusion. Cerenkov luminescence tomography (CLT) for optical photons produced in tissues by several radionuclides (i.e.: 32P, 18F, 90Y), has been investigated using both 3D multispectral approach and multiviews methods. Difficult in convergence of 3D algorithms can discourage to use this technique to have information of depth and intensity of source. For these reasons, we developed a faster 2D corrected approach based on multispectral acquisitions, to obtain source depth and its intensity using a pixel-based fitting of source intensity. Monte Carlo simulations and experimental data were used to develop and validate the method to obtain the parametric map of source depth. With this approach we obtain parametric source depth maps with a precision between 3% and 7% for MC simulation and 5-6% for experimental data. Using this method we are able to obtain reliable information about the source depth of Cerenkov luminescence with a simple and flexible procedure.

  2. Terahertz parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Kawase, Kodo; Ogawa, Yuichi; Minamide, Hiroaki; Ito, Hiromasa

    2005-07-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of LiNbO3 or MgO-doped LiNbO3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave source with a simple configuration. We report the detailed characteristics of the oscillation and the radiation including tunability, spatial and temporal coherency, uni-directivity, and efficiency. A Fourier transform limited THz-wave spectrum narrowing was achieved by introducing the injection seeding method. Further, we have developed a spectroscopic THz imaging system using a THz-wave parametric oscillator, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. Several images of the envelope are recorded at different THz frequencies and then processed. The final result is an image that reveals what substances are present in the envelope, in what quantity, and how they are distributed across the envelope area. The example presented here shows the identification of three drugs, two of which are illegal, while one is an over-the-counter drug.

  3. Generalized parametric down conversion, many particle interferometry, and Bell's theorem

    NASA Technical Reports Server (NTRS)

    Choi, Hyung Sup

    1992-01-01

    A new field of multi-particle interferometry is introduced using a nonlinear optical spontaneous parametric down conversion (SPDC) of a photon into more than two photons. The study of SPDC using a realistic Hamiltonian in a multi-mode shows that at least a low conversion rate limit is possible. The down converted field exhibits many stronger nonclassical phenomena than the usual two photon parametric down conversion. Application of the multi-particle interferometry to a recently proposed many particle Bell's theorem on the Einstein-Podolsky-Rosen problem is given.

  4. Near-self-imaging cavity for three-mode optoacoustic parametric amplifiers using silicon microresonators.

    PubMed

    Liu, Jian; Torres, F A; Ma, Yubo; Zhao, C; Ju, L; Blair, D G; Chao, S; Roch-Jeune, I; Flaminio, R; Michel, C; Liu, K-Y

    2014-02-10

    Three-mode optoacoustic parametric amplifiers (OAPAs), in which a pair of photon modes are strongly coupled to an acoustic mode, provide a general platform for investigating self-cooling, parametric instability and very sensitive transducers. Their realization requires an optical cavity with tunable transverse modes and a high quality-factor mirror resonator. This paper presents the design of a table-top OAPA based on a near-self-imaging cavity design, using a silicon torsional microresonator. The design achieves a tuning coefficient for the optical mode spacing of 2.46  MHz/mm. This allows tuning of the mode spacing between amplification and self-cooling regimes of the OAPA device. Based on demonstrated resonator parameters (frequencies ∼400  kHz and quality-factors ∼7.5×10(5) we predict that the OAPA can achieve parametric instability with 1.6 μW of input power and mode cooling by a factor of 1.9×10(4) with 30 mW of input power.

  5. All-fiber optical parametric oscillator for bio-medical imaging applications

    NASA Astrophysics Data System (ADS)

    Gottschall, Thomas; Meyer, Tobias; Jauregui, Cesar; Just, Florian; Eidam, Tino; Schmitt, Michael; Popp, Jürgen; Limpert, Jens; Tünnermann, Andreas

    2017-02-01

    Among other modern imaging techniques, stimulated Raman Scattering (SRS) requires an extremely quiet, widely wavelength tunable laser, which, up to now, is unheard of in fiber laser systems. We present a compact all-fiber laser system, which features an optical parametric oscillator (OPO) based on degenerate four-wave mixing (FWM) in an endlessly single-mode photonic-crystal fiber. We employ an all-fiber frequency and repetition rate tunable laser in order to enable wideband conversion in the linear OPO cavity arrangement, the signal and idler radiation can be tuned between 764 and 960 nm and 1164 and 1552 nm at 9.5 MHz. Thus, all biochemically relevant Raman shifts between 922 and 3322 cm-1 may be addressed in combination with a secondary output, which is tunable between 1024 and 1052 nm. This ultra-low noise output emits synchronized pulses with twice the repetition rate to enable SRS imaging. We measure the relative intensity noise of this output beam at 9.5 MHz to be between -145 and -148 dBc, which is low enough to enable high-speed SRS imaging with a good signal-to-noise ratio. The laser system is computer controlled to access a certain energy differences within one second. Combining FWM based conversion, with all-fiber Yb-based fiber lasers enables the construction of the first automated, turn-key and widely tunable fiber laser. This laser concept could be the missing piece to establish CRS imaging as a reliable guiding tool for clinical diagnostics and surgical guidance.

  6. High-average-power 2 μm few-cycle optical parametric chirped pulse amplifier at 100 kHz repetition rate.

    PubMed

    Shamir, Yariv; Rothhardt, Jan; Hädrich, Steffen; Demmler, Stefan; Tschernajew, Maxim; Limpert, Jens; Tünnermann, Andreas

    2015-12-01

    Sources of long wavelengths few-cycle high repetition rate pulses are becoming increasingly important for a plethora of applications, e.g., in high-field physics. Here, we report on the realization of a tunable optical parametric chirped pulse amplifier at 100 kHz repetition rate. At a central wavelength of 2 μm, the system delivered 33 fs pulses and a 6 W average power corresponding to 60 μJ pulse energy with gigawatt-level peak powers. Idler absorption and its crystal heating is experimentally investigated for a BBO. Strategies for further power scaling to several tens of watts of average power are discussed.

  7. Optical parametric oscillation in a random poly-crystalline medium: ZnSe ceramic

    NASA Astrophysics Data System (ADS)

    Ru, Qitian; Kawamori, Taiki; Lee, Nathaniel; Chen, Xuan; Zhong, Kai; Mirov, Mike; Vasilyev, Sergey; Mirov, Sergey B.; Vodopyanov, Konstantin L.

    2018-02-01

    We demonstrate an optical parametric oscillator (OPO) based on random phase matching in a polycrystalline χ(2) material, ZnSe. The subharmonic OPO utilized a 1.5-mm-long polished ZnSe ceramic sample placed at the Brewster's angle and was synchronously pumped by a Kerr-lens mode-locked Cr:ZnS laser with a central wavelength of 2.35 μm, a pulse duration of 62 fs, and a repetition frequency of 79 MHz. The OPO had a 90-mW pump threshold, and produced an ultrabroadband spectrum spanning 3-7.5 μm. The observed pump depletion was as high as 79%. The key to success in achieving the OPO action was choosing the average grain size of the ZnSe ceramic to be close to the coherence length ( 100 μm) for our 3-wave interaction. This is the first OPO that uses random polycrystalline material with quadratic nonlinearity and the first OPO based on ZnSe. Very likely, random phase matching in ZnSe and similar random polycrystalline materials (ZnS, CdS, CdSe, GaP) represents a viable route for generating few-cycle pulses and multi-octave frequency combs, thanks to a very broadband nonlinear response.

  8. Quantum information tapping using a fiber optical parametric amplifier with noise figure improved by correlated inputs.

    PubMed

    Guo, Xueshi; Li, Xiaoying; Liu, Nannan; Ou, Z Y

    2016-07-26

    One of the important functions in a communication network is the distribution of information. It is not a problem to accomplish this in a classical system since classical information can be copied at will. However, challenges arise in quantum system because extra quantum noise is often added when the information content of a quantum state is distributed to various users. Here, we experimentally demonstrate a quantum information tap by using a fiber optical parametric amplifier (FOPA) with correlated inputs, whose noise is reduced by the destructive quantum interference through quantum entanglement between the signal and the idler input fields. By measuring the noise figure of the FOPA and comparing with a regular FOPA, we observe an improvement of 0.7 ± 0.1 dB and 0.84 ± 0.09 dB from the signal and idler outputs, respectively. When the low noise FOPA functions as an information splitter, the device has a total information transfer coefficient of Ts+Ti = 1.5 ± 0.2, which is greater than the classical limit of 1. Moreover, this fiber based device works at the 1550 nm telecom band, so it is compatible with the current fiber-optical network for quantum information distribution.

  9. Stimulated parametric emission microscopy.

    PubMed

    Isobe, Keisuke; Kataoka, Shogo; Murase, Rena; Watanabe, Wataru; Higashi, Tsunehito; Kawakami, Shigeki; Matsunaga, Sachihiro; Fukui, Kiichi; Itoh, Kazuyoshi

    2006-01-23

    We propose a novel microscopy technique based on the four-wave mixing (FWM) process that is enhanced by two-photon electronic resonance induced by a pump pulse along with stimulated emission induced by a dump pulse. A Ti:sapphire laser and an optical parametric oscillator are used as light sources for the pump and dump pulses, respectively. We demonstrate that our proposed FWM technique can be used to obtain a one-dimensional image of ethanol-thinned Coumarin 120 solution sandwiched between a hole-slide glass and a cover slip, and a two-dimensional image of a leaf of Camellia sinensis.

  10. Ultra-flat wideband single-pump Raman-enhanced parametric amplification.

    PubMed

    Gordienko, V; Stephens, M F C; El-Taher, A E; Doran, N J

    2017-03-06

    We experimentally optimize a single pump fiber optical parametric amplifier in terms of gain spectral bandwidth and gain variation (GV). We find that optimal performance is achieved with the pump tuned to the zero-dispersion wavelength of dispersion stable highly nonlinear fiber (HNLF). We demonstrate further improvement of parametric gain bandwidth and GV by decreasing the HNLF length. We discover that Raman and parametric gain spectra produced by the same pump may be merged together to enhance overall gain bandwidth, while keeping GV low. Consequently, we report an ultra-flat gain of 9.6 ± 0.5 dB over a range of 111 nm (12.8 THz) on one side of the pump. Additionally, we demonstrate amplification of a 60 Gbit/s QPSK signal tuned over a portion of the available bandwidth with OSNR penalty less than 1 dB for Q2 below 14 dB.

  11. Effect of Zuogui Pill () on monoamine neurotransmitters and sex hormones in climacteric rats with panic attack.

    PubMed

    Li, Xiao-Yu; Wang, Xiao-Yun

    2017-03-01

    To explore the effects of Chinese medicine prescription Zuogui Pill (, ZGP) on monoamine neurotransmitters and sex hormones in climacteric rats with induced panic attacks. Forty-eight climacteric female rats were randomized into 6 groups with 8 rats in each group: the control group, the model group, the low-, medium- and high-dose ZGP groups and the alprazolam group. Rats in the low-, medium- and high-dose ZGP groups were administered 4.725, 9.45, or 18.9 g/kg ZGP by gastric perfusion, respectively. The alprazolam group was treated by gastric perfusion with 0.036 mg/kg alprazolam. The control and model groups were treated with distilled water. The animals were pretreated once daily for 8 consecutive weeks. The behaviors of rats in the open fifield test and the elevated T-maze (ETM) were observed after induced panic attack, and the levels of brain monoamine neurotransmitters and the plasma levels of sex hormones were measured. Compared with the control group, the mean ETM escape time and the levels of 5-hydroxytryptamine (5-HT) and noradrenalin (NE) of the model group were signifificantly reduced (P<0.05), Compared with the model group, the mean ETM escape time and the 5-HT and NE levels of all the ZGP groups increased signifificantly (P<0.05 or P<0.01). However, no signifificant difference was observed in the levels of sex hormones between the groups. Pretreatment with ZGP in climacteric rats may improve the behavior of panic attack, which may be related to increased 5-HT and NE in the brain.

  12. Ten-watt level picosecond parametric mid-IR source broadly tunable in wavelength

    NASA Astrophysics Data System (ADS)

    Vyvlečka, Michal; Novák, Ondřej; Roškot, Lukáscaron; Smrž, Martin; Mužík, Jiří; Endo, Akira; Mocek, Tomáš

    2018-02-01

    Mid-IR wavelength range (between 2 and 8 μm) offers perspective applications, such as minimally-invasive neurosurgery, gas sensing, or plastic and polymer processing. Maturity of high average power near-IR lasers is beneficial for powerful mid-IR generation by optical parametric conversion. We utilize in-house developed Yb:YAG thin-disk laser of 100 W average power at 77 kHz repetition rate, wavelength of 1030 nm, and about 2 ps pulse width for pumping of a ten-watt level picosecond mid-IR source. Seed beam is obtained by optical parametric generation in a double-pass 10 mm long PPLN crystal pumped by a part of the fundamental near-IR beam. Tunability of the signal wavelength between 1.46 μm and 1.95 μm was achieved with power of several tens of miliwatts. Main part of the fundamental beam pumps an optical parametric amplification stage, which includes a walk-off compensating pair of 10 mm long KTP crystals. We already demonstrated the OPA output signal and idler beam tunability between 1.70-1.95 μm and 2.18-2.62 μm, respectively. The signal and idler beams were amplified up to 8.5 W and 5 W, respectively, at 42 W pump without evidence of strong saturation. Thus, increase in signal and idler output power is expected for pump power increase.

  13. Two-stage optical parametric chirped-pulse amplifier using sub-nanosecond pump pulse generated by stimulated Brillouin scattering compression

    NASA Astrophysics Data System (ADS)

    Ogino, Jumpei; Miyamoto, Sho; Matsuyama, Takahiro; Sueda, Keiichi; Yoshida, Hidetsugu; Tsubakimoto, Koji; Miyanaga, Noriaki

    2014-12-01

    We demonstrate optical parametric chirped-pulse amplification (OPCPA) based on two-beam pumping, using sub-nanosecond pulses generated by stimulated Brillouin scattering compression. Seed pulse energy, duration, and center wavelength were 5 nJ, 220 ps, and ˜1065 nm, respectively. The 532 nm pulse from a Q-switched Nd:YAG laser was compressed to ˜400 ps in heavy fluorocarbon FC-40 liquid. Stacking of two time-delayed pump pulses reduced the amplifier gain fluctuation. Using a walk-off-compensated two-stage OPCPA at a pump energy of 34 mJ, a total gain of 1.6 × 105 was obtained, yielding an output energy of 0.8 mJ. The amplified chirped pulse was compressed to 97 fs.

  14. Broadband and tunable optical parametric generator for remote detection of gas molecules in the short and mid-infrared.

    PubMed

    Lambert-Girard, Simon; Allard, Martin; Piché, Michel; Babin, François

    2015-04-01

    The development of a novel broadband and tunable optical parametric generator (OPG) is presented. The OPG properties are studied numerically and experimentally in order to optimize the generator's use in a broadband spectroscopic LIDAR operating in the short and mid-infrared. This paper discusses trade-offs to be made on the properties of the pump, crystal, and seeding signal in order to optimize the pulse spectral density and divergence while enabling energy scaling. A seed with a large spectral bandwidth is shown to enhance the pulse-to-pulse stability and optimize the pulse spectral density. A numerical model shows excellent agreement with output power measurements; the model predicts that a pump having a large number of longitudinal modes improves conversion efficiency and pulse stability.

  15. Development of suspended core soft glass fibers for far-detuned parametric conversion

    NASA Astrophysics Data System (ADS)

    Rampur, Anupamaa; Ciąćka, Piotr; Cimek, Jarosław; Kasztelanic, Rafał; Buczyński, Ryszard; Klimczak, Mariusz

    2018-04-01

    Light sources utilizing χ (2) parametric conversion combine high brightness with attractive operation wavelengths in the near and mid-infrared. In optical fibers, it is possible to use χ (3) degenerate four-wave mixing in order to obtain signal-to-idler frequency detuning of over 100 THz. We report on a test series of nonlinear soft glass suspended core fibers intended for parametric conversion of 1000-1100 nm signal wavelengths available from an array of mature lasers into the near-to-mid-infrared range of 2700-3500 nm under pumping with an erbium sub-picosecond laser system. The presented discussion includes modelling of the fiber properties, details of their physical development and characterization, and experimental tests of parametric conversion.

  16. Multivariable Parametric Cost Model for Ground Optical Telescope Assembly

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Rowell, Ginger Holmes; Reese, Gayle; Byberg, Alicia

    2005-01-01

    A parametric cost model for ground-based telescopes is developed using multivariable statistical analysis of both engineering and performance parameters. While diameter continues to be the dominant cost driver, diffraction-limited wavelength is found to be a secondary driver. Other parameters such as radius of curvature are examined. The model includes an explicit factor for primary mirror segmentation and/or duplication (i.e., multi-telescope phased-array systems). Additionally, single variable models Based on aperture diameter are derived.

  17. Multivariable Parametric Cost Model for Ground Optical: Telescope Assembly

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Rowell, Ginger Holmes; Reese, Gayle; Byberg, Alicia

    2004-01-01

    A parametric cost model for ground-based telescopes is developed using multi-variable statistical analysis of both engineering and performance parameters. While diameter continues to be the dominant cost driver, diffraction limited wavelength is found to be a secondary driver. Other parameters such as radius of curvature were examined. The model includes an explicit factor for primary mirror segmentation and/or duplication (i.e. multi-telescope phased-array systems). Additionally, single variable models based on aperture diameter were derived.

  18. Narrow-bandwidth tunable picosecond pulses in the visible produced by noncollinear optical parametric amplification with a chirped blue pump.

    PubMed

    Co, Dick T; Lockard, Jenny V; McCamant, David W; Wasielewski, Michael R

    2010-04-01

    Narrow-bandwidth (approximately 27 cm(-1)) tunable picosecond pulses from 480 nm-780 nm were generated from the output of a 1 kHz femtosecond titanium:sapphire laser system using a type I noncollinear optical parametric amplifier (NOPA) with chirped second-harmonic generation (SHG) pumping. Unlike a femtosecond NOPA, this system utilizes a broadband pump beam, the chirped 400 nm SHG of the Ti:sapphire fundamental, to amplify a monochromatic signal beam (spectrally-filtered output of a type II collinear OPA). Optimum geometric conditions for simultaneous phase- and group-velocity matching were calculated in the visible spectrum. This design is an efficient and simple method for generating tunable visible picosecond pulses that are synchronized to the femtosecond pulses.

  19. Parametric instabilities and their control in multidimensional nonuniform gain media

    NASA Astrophysics Data System (ADS)

    Charbonneau-Lefort, Mathieu; Afeyan, Bedros; Fejer, Martin

    2007-11-01

    In order to control parametric instabilities in large scale long pulse laser produced plasmas, optical mixing techniques seem most promising [1]. We examine ways of controlling the growth of some modes while creating other unstable ones in nonuniform gain media, including the effects of transverse localization of the pump wave. We show that multidimensional effects are essential to understand laser-gain medium interactions [2] and that one dimensional models such as the celebrated Rosenbluth result [3] can be misleading [4]. These findings are verified in experiments carried out in a chirped quasi-phase-matched gratings in optical parametric amplifiers where thousands of shots can be taken and statistically significant and stable results obtained. [1] B. Afeyan, et al., IFSA Proceedings, 2003. [2] M. M. Sushchik and G. I. Freidman, Radiofizika 13, 1354 (1970). [3] M. N. Rosenbluth, Phys. Rev. Lett. 29, 565 (1972). [4] M. Charbonneau-Lefort, PhD thesis, Stanford University, 2007.

  20. CuBe: parametric modeling of 3D foveal shape using cubic Bézier

    PubMed Central

    Yadav, Sunil Kumar; Motamedi, Seyedamirhosein; Oberwahrenbrock, Timm; Oertel, Frederike Cosima; Polthier, Konrad; Paul, Friedemann; Kadas, Ella Maria; Brandt, Alexander U.

    2017-01-01

    Optical coherence tomography (OCT) allows three-dimensional (3D) imaging of the retina, and is commonly used for assessing pathological changes of fovea and macula in many diseases. Many neuroinflammatory conditions are known to cause modifications to the fovea shape. In this paper, we propose a method for parametric modeling of the foveal shape. Our method exploits invariant features of the macula from OCT data and applies a cubic Bézier polynomial along with a least square optimization to produce a best fit parametric model of the fovea. Additionally, we provide several parameters of the foveal shape based on the proposed 3D parametric modeling. Our quantitative and visual results show that the proposed model is not only able to reconstruct important features from the foveal shape, but also produces less error compared to the state-of-the-art methods. Finally, we apply the model in a comparison of healthy control eyes and eyes from patients with neuroinflammatory central nervous system disorders and optic neuritis, and show that several derived model parameters show significant differences between the two groups. PMID:28966857

  1. Subpicosecond Optical Digital Computation Using Conjugate Parametric Generators

    DTIC Science & Technology

    1989-03-31

    Using Phase Conjugate Farametric Generators ..... 12. PERSONAL AUTHOR(S) Alfano, Robert- Eichmann . George; Dorsinville. Roger! Li. Yao 13a. TYPE OF...conjugation-based optical residue arithmetic processor," Y. Li, G. Eichmann , R. Dorsinville, and R. R. Alfano, Opt. Lett. 13, (1988). [2] "Parallel ultrafast...optical digital and symbolic computation via optical phase conjugation," Y. Li, G. Eichmann , R. Dorsinville, Appl. Opt. 27, 2025 (1988). [3

  2. Note: Pulsed single longitudinal mode optical parametric oscillator for sub-Doppler spectroscopy of jet cooled transient species

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Zhu, Boxing; Zhang, Deping; Gu, Jingwang; Zhao, Dongfeng; Chen, Yang

    2017-12-01

    We present a pulsed single longitudinal mode optical parametric oscillator that was recently constructed for sub-Doppler spectroscopic studies of transient species in a supersonic slit jet expansion environment. The system consists of a Littman-type grazing-incidence-grating resonator and a KTP crystal and is pumped at 532 nm. By spatially filtering the pump laser beam and employing an active cavity-length-stabilization scheme, a frequency down-conversion efficiency up to 18% and generation of Fourier-transform limited pulses with a typical pulse duration of ˜5.5 ns and a bandwidth less than 120 MHz have been achieved. In combination with a slit jet expansion, a sub-Doppler spectrum of SiC2 has been recorded at ˜498 nm, showing a spectral resolution of Δν/ν ≈ 6.2 × 10-7.

  3. Quasi-Phasematched Nonlinear Optics: Materials and Devices

    DTIC Science & Technology

    2007-04-16

    the soliton energy in pump, signal and idler waves as a function of the final wave- vector mismatch in the chirped QPM gratings. We see good agreement...devices including OP-GaAs devices for broadband optical parametric generation (OPG) at mid-infrared wavelengths, bulk PPLN devices for soliton ...Carrasco, and L. Torner,"Engineering of multi-color spatial solitons with chirped-period quasi-phase-matching gratings in optical parametric amplification

  4. Low Noise Optical Amplifiers

    DTIC Science & Technology

    2010-05-01

    Karsten Rottwitt DTU Fotonik Department of Photonics Engineering, Technical University of Denmark - 2 - TABLE OF...at DTU Fotonik, has intensified through two new ph.d positions within parametric amplifiers, one partly funded through a research program on phase...Activities: As indicated in the above DTU Fotonik now has significant activities on using parametric processes in optical fibers. This includes

  5. Parametric bicubic spline and CAD tools for complex targets shape modelling in physical optics radar cross section prediction

    NASA Astrophysics Data System (ADS)

    Delogu, A.; Furini, F.

    1991-09-01

    Increasing interest in radar cross section (RCS) reduction is placing new demands on theoretical, computation, and graphic techniques for calculating scattering properties of complex targets. In particular, computer codes capable of predicting the RCS of an entire aircraft at high frequency and of achieving RCS control with modest structural changes, are becoming of paramount importance in stealth design. A computer code, evaluating the RCS of arbitrary shaped metallic objects that are computer aided design (CAD) generated, and its validation with measurements carried out using ALENIA RCS test facilities are presented. The code, based on the physical optics method, is characterized by an efficient integration algorithm with error control, in order to contain the computer time within acceptable limits, and by an accurate parametric representation of the target surface in terms of bicubic splines.

  6. High-energy, tunable, mid-infrared, picosecond optical parametric generation in CdSiP2

    NASA Astrophysics Data System (ADS)

    Chaitanya Kumar, S.; Jelínek, M.; Baudisch, M.; Zawilski, K. T.; Schunemann, P. G.; Kubecek, V.; Biegert, J.; Ebrahim-Zadeh, M.

    2012-06-01

    We report a tunable, high-energy, single-pass, optical parametric generator (OPG) based on the new nonlinear material, cadmium silicon phosphide, CdSiP2. The OPG is pumped by a laboratory designed cavity-dumped passively mode-locked, diode-pumped, Nd:YAG oscillator, providing 25 μJ pulses in 20 ps at 5 Hz. The pump energy is further boosted by a flashlamp-pumped Nd:YAG amplifier to 2.5 mJ. The OPG is temperature tunable over 1263-1286 nm (23 nm) in the signal and 6153-6731 nm (578 nm) in the idler, corresponding to a total tuning range of 601 nm. Using the single-pass OPG configuration, we have generated signal energy as high as 636 μJ at 1283 nm, together with an idler energy of 33 μJ at 6234 nm, for 2.1 mJ of input pump energy. The signal pulses generated from the OPG have a Gaussian pulse duration of 24 ps and an FWHM spectral bandwidth of 10.4 nm at central wavelength of 1276 nm. The corresponding idler spectrum has an FWHM bandwidth of 140 nm centered at 6404 nm.

  7. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    PubMed

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

  8. Statistical parametric mapping of stimuli-evoked changes in quantitative blood flow using extended-focus optical coherence microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Marchand, Paul J.; Bouwens, Arno; Shamaei, Vincent; Nguyen, David; Extermann, Jerome; Bolmont, Tristan; Lasser, Theo

    2016-03-01

    Magnetic Resonance Imaging has revolutionised our understanding of brain function through its ability to image human cerebral structures non-invasively over the entire brain. By exploiting the different magnetic properties of oxygenated and deoxygenated blood, functional MRI can indirectly map areas undergoing neural activation. Alongside the development of fMRI, powerful statistical tools have been developed in an effort to shed light on the neural pathways involved in processing of sensory and cognitive information. In spite of the major improvements made in fMRI technology, the obtained spatial resolution of hundreds of microns prevents MRI in resolving and monitoring processes occurring at the cellular level. In this regard, Optical Coherence Microscopy is an ideal instrumentation as it can image at high spatio-temporal resolution. Moreover, by measuring the mean and the width of the Doppler spectra of light scattered by moving particles, OCM allows extracting the axial and lateral velocity components of red blood cells. The ability to assess quantitatively total blood velocity, as opposed to classical axial velocity Doppler OCM, is of paramount importance in brain imaging as a large proportion of cortical vascular is oriented perpendicularly to the optical axis. We combine here quantitative blood flow imaging with extended-focus Optical Coherence Microscopy and Statistical Parametric Mapping tools to generate maps of stimuli-evoked cortical hemodynamics at the capillary level.

  9. Optical characterization in wide spectral range by a coherent spectrophotometer

    NASA Astrophysics Data System (ADS)

    Sirutkaitis, Valdas; Eckardt, Robert C.; Balachninaite, Ona; Grigonis, Rimantas; Melninkaitis, A.; Rakickas, T.

    2003-11-01

    We report on the development and use of coherent spectrophotometers specialized for the unusual requirements of characterizing nonlinear optical materials and multilayer dielectric coatings used in laser systems. A large dynamic range is required to measure the linear properties of transmission, reflection and absorption and nonlinear properties of laser-induced damage threshold and nonlinear frequency conversion. Optical parametric oscillators generate coherent radiation that is widely tunable with instantaneous powers that can range from milliwatts to megawatts and are well matched to this application. As particular example a laser spectrophotometer based on optical parametric oscillators and a diode-pumped, Q-switched Nd:YAG laser and suitable for optical characterization in the spectral range 420-4500 nm is described. Measurements include reflectance and transmittance, absorption, scattering and laser-induced damage thresholds. Possibilities of a system based on a 130-fs Ti:sapphire laser and optical parametric generators are also discussed.

  10. Generation of high-energy sub-20 fs pulses tunable in the 250-310 nm region by frequency doubling of a high-power noncollinear optical parametric amplifier.

    PubMed

    Beutler, Marcus; Ghotbi, Masood; Noack, Frank; Brida, Daniele; Manzoni, Cristian; Cerullo, Giulio

    2009-03-15

    We report on the generation of powerful sub-20 fs deep UV pulses with 10 microJ level energy and broadly tunable in the 250-310 nm range. These pulses are produced by frequency doubling a high-power noncollinear optical parametric amplifier and compressed by a pair of MgF2 prisms to an almost transform-limited duration. Our results provide a power scaling by an order of magnitude with respect to previous works.

  11. Nondegenerate parametric generation of 2.2-mJ, few-cycle 2.05-μm pulses using a mixed phase matching scheme

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Guibao; Wandel, Scott F.; Jovanovic, Igor, E-mail: ijovanovic@psu.edu

    2014-02-15

    We describe the production of 2.2-mJ, ∼6 optical-cycle-long mid-infrared laser pulses with a carrier wavelength of 2.05 μm in a two-stage β-BaB{sub 2}O{sub 4} nondegenerate optical parametric amplifier design with a mixed phase matching scheme, which is pumped by a standard Ti:sapphire chirped-pulse amplification system. It is demonstrated that relatively high pulse energies, short pulse durations, high stability, and excellent beam profiles can be obtained using this simple approach, even without the use of optical parametric chirped-pulse amplification.

  12. Parametric Instability Rates in Periodically Driven Band Systems

    NASA Astrophysics Data System (ADS)

    Lellouch, S.; Bukov, M.; Demler, E.; Goldman, N.

    2017-04-01

    In this work, we analyze the dynamical properties of periodically driven band models. Focusing on the case of Bose-Einstein condensates, and using a mean-field approach to treat interparticle collisions, we identify the origin of dynamical instabilities arising from the interplay between the external drive and interactions. We present a widely applicable generic numerical method to extract instability rates and link parametric instabilities to uncontrolled energy absorption at short times. Based on the existence of parametric resonances, we then develop an analytical approach within Bogoliubov theory, which quantitatively captures the instability rates of the system and provides an intuitive picture of the relevant physical processes, including an understanding of how transverse modes affect the formation of parametric instabilities. Importantly, our calculations demonstrate an agreement between the instability rates determined from numerical simulations and those predicted by theory. To determine the validity regime of the mean-field analysis, we compare the latter to the weakly coupled conserving approximation. The tools developed and the results obtained in this work are directly relevant to present-day ultracold-atom experiments based on shaken optical lattices and are expected to provide an insightful guidance in the quest for Floquet engineering.

  13. Yb-fiber-pumped mid-infrared picosecond optical parametric oscillator tunable across 6.2-6.7 µm

    NASA Astrophysics Data System (ADS)

    Kumar, S. Chaitanya; Casals, J. Canals; Parsa, S.; Zawilski, K. T.; Schunemann, P. G.; Ebrahim-Zadeh, M.

    2018-06-01

    We report a high-average-power picosecond optical parametric oscillator (OPO) tunable in the mid-infrared (mid-IR) based on CdSiP2 synchronously pumped by an Yb-fiber laser at 80 MHz repetition rate. Successful operation of this high-repetition-rate singly-resonant picosecond OPO has been enabled by the improved CSP crystal quality over a long interaction length. The OPO can be tuned across 1264-1284 nm in the near-IR signal and 6205-6724 nm in the mid-IR idler by temperature tuning the CSP crystal over 39-134 °C. By deploying a 5% output coupler for the resonant signal, we have extracted up to 44 mW of average power in the near-IR and up to 95 mW of non-resonant idler power at 6205 nm at 6.3% total conversion efficiency, with > 50 mW over > 55% of the mid-IR tuning range. We have investigated temperature-tuning characteristics of the OPO and compared the data with the theoretical calculations using the recent Sellmeier and thermo-optic coefficients for CdSiP2. The signal pulses from the OPO exhibit a Gaussian pulse duration of 19 ps centered at 1284 nm. We have also studied the output power stability of the OPO, resulting in a passive stability better than 1.9% rms for the near-IR signal and 2.4% rms for the mid-IR idler, measured over > 17 h, with both beams in high spatial quality.

  14. Parametric Cost Deployment

    NASA Technical Reports Server (NTRS)

    Dean, Edwin B.

    1995-01-01

    Parametric cost analysis is a mathematical approach to estimating cost. Parametric cost analysis uses non-cost parameters, such as quality characteristics, to estimate the cost to bring forth, sustain, and retire a product. This paper reviews parametric cost analysis and shows how it can be used within the cost deployment process.

  15. Optomechanical entanglement via non-degenerate parametric interactions

    NASA Astrophysics Data System (ADS)

    Ahmed, Rizwan; Qamar, Shahid

    2017-10-01

    We present a scheme for the optomechanical entanglement between a micro-mechanical mirror and the field inside a bimodal cavity system using a non-degenerate optical parametric amplifier (NOPA). Our results show that the introduction of NOPA makes the entanglement stronger or more robust against the mean number of average thermal phonons and cavity decay. Interestingly, macroscopic entanglement depends upon the choice of the phase associated with classical field driving NOPA. We also consider the effects of input laser power on optomechanical entanglement.

  16. High power, widely tunable dual-wavelength 2 μm laser based on intracavity KTP optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Yan, Dexian; Wang, Yuye; Xu, Degang; Shi, Wei; Zhong, Kai; Liu, Pengxiang; Yan, Chao; Mei, Jialin; Shi, Jia; Yao, Jianquan

    2017-01-01

    We presented a high power, widely tunable narrowband 2 μm dual-wavelength source employing intracavity optical parametric oscillator with potassium titanium oxide phosphate (KTP) crystal. Two identical KTP crystals were oriented oppositely in the OPO cavity to compensate the walk-off effect. The output average power of dual-wavelength 2 μm laser was up to 18.18 W at 10 kHz with the peak power of 165 kW. The two wavelengths can be tuned in the range of 2070.7 nm to 2191.1 nm for ordinary light while in the range of 2190.7 nm to 2065.9 nm for extraordinary light with the full width at half maximum (FWHM) about 0.8 nm. The pulse width of the tunable laser was as narrow as 11 ns. The beam quality factor M 2 was less than 4 during wavelength tuning.

  17. Three-Dimensional Unstained Live-Cell Imaging Using Stimulated Parametric Emission Microscopy

    NASA Astrophysics Data System (ADS)

    Dang, Hieu M.; Kawasumi, Takehito; Omura, Gen; Umano, Toshiyuki; Kajiyama, Shin'ichiro; Ozeki, Yasuyuki; Itoh, Kazuyoshi; Fukui, Kiichi

    2009-09-01

    The ability to perform high-resolution unstained live imaging is very important to in vivo study of cell structures and functions. Stimulated parametric emission (SPE) microscopy is a nonlinear-optical microscopy based on ultra-fast electronic nonlinear-optical responses. For the first time, we have successfully applied this technique to archive three-dimensional (3D) images of unstained sub-cellular structures, such as, microtubules, nuclei, nucleoli, etc. in live cells. Observation of a complete cell division confirms the ability of SPE microscopy for long time-scale imaging.

  18. Numerical investigation of output beam quality in efficient broadband optical parametric chirped pulse amplification

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Di; Xu, Lu; Liang, Xiao-Yan

    2017-01-01

    We theoretically analyzed output beam quality of broad bandwidth non-collinear optical parametric chirped pulse amplification (NOPCPA) in LiB3O5 (LBO) centered at 800 nm. With a three-dimensional numerical model, the influence of the pump intensity, pump and signal spatial modulations, and the walk-off effect on the OPCPA output beam quality are presented, together with conversion efficiency and the gain spectrum. The pump modulation is a dominant factor that affects the output beam quality. Comparatively, the influence of signal modulation is insignificant. For a low-energy system with small beam sizes, walk-off effect has to be considered. Pump modulation and walk-off effect lead to asymmetric output beam profile with increased modulation. A special pump modulation type is found to optimize output beam quality and efficiency. For a high-energy system with large beam sizes, the walk-off effect can be neglected, certain back conversion is beneficial to reduce the output modulation. A trade-off must be made between the output beam quality and the conversion efficiency, especially when the pump modulation is large since. A relatively high conversion efficiency and a low output modulation are both achievable by controlling the pump modulation and intensity.

  19. Fiber-laser-based, green-pumped, picosecond optical parametric oscillator using fan-out grating PPKTP.

    PubMed

    Chaitanya Kumar, S; Parsa, S; Ebrahim-Zadeh, M

    2016-01-01

    We report a stable, Yb-fiber-laser-based, green-pumped, picosecond optical parametric oscillator (OPO) for the near-infrared based on periodically poled potassium titanyl phosphate (PPKTP) nonlinear crystal, using fan-out grating design and operating near room temperature. The OPO is continuously tunable across 726-955 nm in the signal and 1201-1998 nm in the idler, resulting in a total signal plus idler wavelength coverage of 1026 nm by grating tuning at a fixed temperature. The device generates up to 580 mW of average power in the signal at 765 nm and 300 mW in the idler at 1338 nm, with an overall extraction efficiency of up to 52% and a pump depletion >76%. The extracted signal at 765 nm and idler at 1746 nm exhibit excellent passive power stability better than 0.5% and 0.8% rms, respectively, over 1 h with good beam quality in TEM00 mode profile. The output signal pulses have a Gaussian temporal duration of 13.2 ps, with a FWHM spectral bandwidth of 3.4 nm at 79.5 MHz repetition rate. Power scaling limitations of the OPO due to the material properties of PPKTP are studied.

  20. High-power, continuous-wave, mid-infrared optical parametric oscillator based on MgO:sPPLT.

    PubMed

    Chaitanya Kumar, S; Ebrahim-Zadeh, M

    2011-07-01

    We report a stable, high-power, cw, mid-IR optical parametric oscillator using MgO-doped stoichiometric periodically poled LiTaO₃ (MgO:sPPLT) pumped by a Yb fiber laser at 1064 nm. The singly resonant oscillator (SRO), based on a 30 mm long crystal, is tunable over 430 nm from 3032 to 3462 nm and can generate as much as 5.5 W of mid-IR output power, with >4 W of over 60% of the tuning range and under reduced thermal effects, enabling room temperature operation. Idler power scaling measurements at ~3.3 μm are compared with an MgO-doped periodically poled LiNbO₃ cw SRO, confirming that MgO:sPPLT is an attractive material for multiwatt mid-IR generation. The idler output at 3299 nm exhibits a peak-to-peak power stability better than 12.8% over 5 h and frequency stability of ~1 GHz, while operating close to room temperature, and has a linewidth of ~0.2 nm, limited by the resolution of the wavemeter. The corresponding signal linewidth at 1570 nm is ~21 MHz.

  1. Localization of one-photon state in space and Einstein-Podolsky-Rosen paradox in spontaneous parametric down conversion

    NASA Technical Reports Server (NTRS)

    Penin, A. N.; Reutova, T. A.; Sergienko, A. V.

    1992-01-01

    An experiment on one-photon state localization in space using a correlation technique in Spontaneous Parametric Down Conversion (SPDC) process is discussed. Results of measurements demonstrate an idea of the Einstein-Podolsky-Rosen (EPR) paradox for coordinate and momentum variables of photon states. Results of the experiment can be explained with the help of an advanced wave technique. The experiment is based on the idea that two-photon states of optical electromagnetic fields arising in the nonlinear process of the spontaneous parametric down conversion (spontaneous parametric light scattering) can be explained by quantum mechanical theory with the help of a single wave function.

  2. Localization of one-photon state in space and Einstein-Podolsky-Rosen paradox in spontaneous parametric down conversion

    NASA Astrophysics Data System (ADS)

    Penin, A. N.; Reutova, T. A.; Sergienko, A. V.

    1992-02-01

    An experiment on one-photon state localization in space using a correlation technique in Spontaneous Parametric Down Conversion (SPDC) process is discussed. Results of measurements demonstrate an idea of the Einstein-Podolsky-Rosen (EPR) paradox for coordinate and momentum variables of photon states. Results of the experiment can be explained with the help of an advanced wave technique. The experiment is based on the idea that two-photon states of optical electromagnetic fields arising in the nonlinear process of the spontaneous parametric down conversion (spontaneous parametric light scattering) can be explained by quantum mechanical theory with the help of a single wave function.

  3. Multi-gigahertz, femtosecond Airy beam optical parametric oscillator pumped at 78 MHz

    PubMed Central

    Aadhi, A.; Sharma, Varun; Chaitanya, N. Apurv; Samanta, G. K.

    2017-01-01

    We report a high power ultrafast Airy beam source producing femtosecond pulses at multi-gigahertz (GHz) repetition rate (RR). Based on intra-cavity cubic phase modulation of an optical parametric oscillator (OPO) designed in high harmonic cavity configuration synchronous to a femtosecond Yb-fiber laser operating at 78 MHz, we have produced ultrafast 2D Airy beam at multi-GHz repetition rate through the fractional increment in the cavity length. While small (<1 mm) crystals are used in femtosecond OPOs to take the advantage of broad phase-matching bandwidth, here, we have exploited the extended phase-matching bandwidth of a 50-mm long Magnesium-oxide doped periodically poled LiNbO3 (MgO:PPLN) crystal for efficient generation of ultrafast Airy beam and broadband mid-IR radiation. Pumping the MgO:PPLN crystal of grating period, Λ = 30 μm and crystal temperature, T = 100 °C using a 5-W femtosecond laser centred at 1064 nm, we have produced Airy beam radiation of 684 mW in ~639 fs (transform limited) pulses at 1525 nm at a RR of ~2.5 GHz. Additionally, the source produces broadband idler radiation with maximum power of 510 mW and 94 nm bandwidth at 3548 nm in Gaussian beam profile. Using an indirect method (change in cavity length) we estimate maximum RR of the Airy beam source to be ~100 GHz. PMID:28262823

  4. Electronically tunable femtosecond all-fiber optical parametric oscillator for multi-photon microscopy

    NASA Astrophysics Data System (ADS)

    Hellwig, Tim; Brinkmann, Maximilian; Fallnich, Carsten

    2018-02-01

    We present a femtosecond fiber-based optical parametric oscillator (FOPO) for multiphoton microscopy with wavelength tuning by electronic repetition rate tuning in combination with a dispersive filter in the FOPO cavity. The all-spliced, all-fiber FOPO cavity is based on polarization-maintaining fibers and a broadband output coupler, allowing to get access to the resonant signal pulses as well as the idler pulses simultaneously. The system was pumped by a gain-switched fiber-coupled laser diode emitting pulses at a central wavelength of 1030 nm and an electronically tunable repetition frequency of about 2 MHz. The pump pulses were amplified in an Ytterbium fiber amplifier system with a pulse duration after amplification of 13 ps. Tuning of the idler (1140 nm - 1300 nm) and signal wavelengths (850 nm - 940 nm) was achieved by changing the repetition frequency of the pump laser by about 4 kHz. The generated signal pulses reached a pulse energy of up to 9.2 nJ at 920 nm and were spectrally broadened to about 6 nm in the FOPO by a combination of self-phase and cross-phase modulation. We showed external compression of the idler pulses at 920 nm to about 430 fs and appleid them to two-photon excitation microscopy with green fluorescent dyes. The presented system constitutes an important step towards a fully fiber-integrated all-electronically tunable and, thereby, programmable light source and already embodies a versatile and flexible light source for applications, e.g., for smart microscopy.

  5. Parametric and non-parametric modeling of short-term synaptic plasticity. Part I: computational study

    PubMed Central

    Marmarelis, Vasilis Z.; Berger, Theodore W.

    2009-01-01

    Parametric and non-parametric modeling methods are combined to study the short-term plasticity (STP) of synapses in the central nervous system (CNS). The nonlinear dynamics of STP are modeled by means: (1) previously proposed parametric models based on mechanistic hypotheses and/or specific dynamical processes, and (2) non-parametric models (in the form of Volterra kernels) that transforms the presynaptic signals into postsynaptic signals. In order to synergistically use the two approaches, we estimate the Volterra kernels of the parametric models of STP for four types of synapses using synthetic broadband input–output data. Results show that the non-parametric models accurately and efficiently replicate the input–output transformations of the parametric models. Volterra kernels provide a general and quantitative representation of the STP. PMID:18506609

  6. Relaxed damage threshold intensity conditions and nonlinear increase in the conversion efficiency of an optical parametric oscillator using a bi-directional pump geometry.

    PubMed

    Norris, G; McConnell, G

    2010-03-01

    A novel bi-directional pump geometry that nonlinearly increases the nonlinear optical conversion efficiency of a synchronously pumped optical parametric oscillator (OPO) is reported. This bi-directional pumping method synchronizes the circulating signal pulse with two counter-propagating pump pulses within a linear OPO resonator. Through this pump scheme, an increase in nonlinear optical conversion efficiency of 22% was achieved at the signal wavelength, corresponding to a 95% overall increase in average power. Given an almost unchanged measured pulse duration of 260 fs under optimal performance conditions, this related to a signal wavelength peak power output of 18.8 kW, compared with 10 kW using the traditional single-pass geometry. In this study, a total effective peak intensity pump-field of 7.11 GW/cm(2) (corresponding to 3.55 GW/cm(2) from each pump beam) was applied to a 3 mm long periodically poled lithium niobate crystal, which had a damage threshold intensity of 4 GW/cm(2), without impairing crystal integrity. We therefore prove the application of this novel pump geometry provides opportunities for power-scaling of synchronously pumped OPO systems together with enhanced nonlinear conversion efficiency through relaxed damage threshold intensity conditions.

  7. Study of parametric instability in gravitational wave detectors with silicon test masses

    NASA Astrophysics Data System (ADS)

    Zhang, Jue; Zhao, Chunnong; Ju, Li; Blair, David

    2017-03-01

    Parametric instability is an intrinsic risk in high power laser interferometer gravitational wave detectors, in which the optical cavity modes interact with the acoustic modes of the mirrors, leading to exponential growth of the acoustic vibration. In this paper, we investigate the potential parametric instability for a proposed next generation gravitational wave detector, the LIGO Voyager blue design, with cooled silicon test masses of size 45 cm in diameter and 55 cm in thickness. It is shown that there would be about two unstable modes per test mass at an arm cavity power of 3 MW, with the highest parametric gain of  ∼76. While this is less than the predicted number of unstable modes for Advanced LIGO (∼40 modes with max gain of  ∼32 at the designed operating power of 830 kW), the importance of developing suitable instability suppression schemes is emphasized.

  8. Broadband optical limiting and nonlinear optical absorption properties of a novel hyperbranched conjugated polymer

    NASA Astrophysics Data System (ADS)

    Li, Chao; Liu, Chunling; Li, Quanshui; Gong, Qihuang

    2004-12-01

    The nonlinear transmittance of a novel hyperbranched conjugated polymer named DMA-HPV has been measured in CHCl 3 solution using a nanosecond optical parametric oscillator. DMA-HPV shows excellent optical limiting performance in the visible region from 490 to 610 nm. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its huge and broadband nonlinear optical absorption.

  9. Compact high-pulse-energy passively Q-switched Nd:YLF laser with an ultra-low-magnification unstable resonator: application for efficient optical parametric oscillator.

    PubMed

    Cho, C Y; Huang, Y P; Huang, Y J; Chen, Y C; Su, K W; Chen, Y F

    2013-01-28

    We exploit an ultra-low-magnification unstable resonator to develop a high-pulse-energy side-pumped passively Q-switched Nd:YLF/Cr⁴⁺:YAG laser with improving beam quality. A wedged laser crystal is employed in the cavity to control the emissions at 1047 nm and 1053 nm independently through the cavity alignment. The pulse energies at 1047 nm and 1053 nm are found to be 19 mJ and 23 mJ, respectively. The peak powers for both wavelengths are higher than 2 MW. Furthermore, the developed Nd:YLF lasers are employed to pump a monolithic optical parametric oscillator for confirming the applicability in nonlinear wavelength conversions.

  10. Optimization of mid-IR generation from a periodically poled MgO doped stoichiometric lithium tantalate optical parametric oscillator with intracavity difference frequency mixing

    NASA Astrophysics Data System (ADS)

    Hatano, Hideki; Slater, Richard; Takekawa, Shunji; Kusano, Masahiro; Watanabe, Makoto

    2017-07-01

    We demonstrate 43% slope efficiency for generation of ∼3200 nm light, a wavelength considered to be ideal for laser induced ultrasound generation in carbon fiber reinforced plastic. High slope efficiency was obtained by optimizing crystal lengths, cavity length and mirror reflectivity using a two crystal optical parametric oscillator+difference frequency mixing (OPO+DFM) nonlinear wavelength conversion scheme. Mid-IR output >12 mJ was obtained from a 1064 nm Nd:YAG pump laser with 12 ns pulse width (FWHM) and containing pulse energy of 43 mJ. A compact, single temperature crystal oven is described along with some suggestions for improving the slope efficiency.

  11. Enhanced protection against Ebola virus mediated by an improved adenovirus-based vaccine.

    PubMed

    Richardson, Jason S; Yao, Michel K; Tran, Kaylie N; Croyle, Maria A; Strong, James E; Feldmann, Heinz; Kobinger, Gary P

    2009-01-01

    The Ebola virus is transmitted by direct contact with bodily fluids of infected individuals, eliciting death rates as high as 90% among infected humans. Currently, replication defective adenovirus-based Ebola vaccine is being studied in a phase I clinical trial. Another Ebola vaccine, based on an attenuated vesicular stomatitis virus has shown efficacy in post-exposure treatment of nonhuman primates to Ebola infection. In this report, we modified the common recombinant adenovirus serotype 5-based Ebola vaccine expressing the wild-type ZEBOV glycoprotein sequence from a CMV promoter (Ad-CMVZGP). The immune response elicited by this improved expression cassette vector (Ad-CAGoptZGP) and its ability to afford protection against lethal ZEBOV challenge in mice was compared to the standard Ad-CMVZGP vector. Ad-CMVZGP was previously shown to protect mice, guinea pigs and nonhuman primates from an otherwise lethal challenge of Zaire ebolavirus. The antigenic expression cassette of this vector was improved through codon optimization, inclusion of a consensus Kozak sequence and reconfiguration of a CAG promoter (Ad-CAGoptZGP). Expression of GP from Ad-CAGoptZGP was substantially higher than from Ad-CMVZGP. Ad-CAGoptZGP significantly improved T and B cell responses at doses 10 to 100-fold lower than that needed with Ad-CMVZGP. Additionally, Ad-CAGoptZGP afforded full protections in mice against lethal challenge at a dose 100 times lower than the dose required for Ad-CMVZGP. Finally, Ad-CAGoptZGP induced full protection to mice when given 30 minutes post-challenge. We describe an improved adenovirus-based Ebola vaccine capable of affording post-exposure protection against lethal challenge in mice. The molecular modifications of the new improved vaccine also translated in the induction of significantly enhanced immune responses and complete protection at a dose 100 times lower than with the previous generation adenovirus-based Ebola vaccine. Understanding and improving the

  12. Tunable, high-repetition-rate, dual-signal-wavelength femtosecond optical parametric oscillator based on BiB3O6

    NASA Astrophysics Data System (ADS)

    Meng, Xianghao; Wang, Zhaohua; Tian, Wenlong; Fang, Shaobo; Wei, Zhiyi

    2018-01-01

    We have demonstrated a high-repetition-rate tunable femtosecond dual-signal-wavelength optical parametric oscillator (OPO) based on BiB3O6 (BiBO) crystal, synchronously pumped by a frequency-doubled mode-locked Yb:KGW laser. The cavity is simple since no dispersion compensators are used in the cavity. The wavelength range of dual-signal is widely tunable from 710 to 1000 nm. Tuning is accomplished by rotating phase-matching angle of BiBO, and optimizing cavity length and output coupler. Using a 3.75 W pump laser, the maximum average dual-signal output power is 760 mW at 707 and 750 nm, leading to a conversion efficiency of 20.3% not taking into account the idler power. Our experimental results show a non-critical phase-matching configuration pumped by a high peak power laser source. The operation of the dual-signal benefits from the balance of phase matching and group velocity mismatching between the two signals.

  13. Parametric vs. non-parametric statistics of low resolution electromagnetic tomography (LORETA).

    PubMed

    Thatcher, R W; North, D; Biver, C

    2005-01-01

    This study compared the relative statistical sensitivity of non-parametric and parametric statistics of 3-dimensional current sources as estimated by the EEG inverse solution Low Resolution Electromagnetic Tomography (LORETA). One would expect approximately 5% false positives (classification of a normal as abnormal) at the P < .025 level of probability (two tailed test) and approximately 1% false positives at the P < .005 level. EEG digital samples (2 second intervals sampled 128 Hz, 1 to 2 minutes eyes closed) from 43 normal adult subjects were imported into the Key Institute's LORETA program. We then used the Key Institute's cross-spectrum and the Key Institute's LORETA output files (*.lor) as the 2,394 gray matter pixel representation of 3-dimensional currents at different frequencies. The mean and standard deviation *.lor files were computed for each of the 2,394 gray matter pixels for each of the 43 subjects. Tests of Gaussianity and different transforms were computed in order to best approximate a normal distribution for each frequency and gray matter pixel. The relative sensitivity of parametric vs. non-parametric statistics were compared using a "leave-one-out" cross validation method in which individual normal subjects were withdrawn and then statistically classified as being either normal or abnormal based on the remaining subjects. Log10 transforms approximated Gaussian distribution in the range of 95% to 99% accuracy. Parametric Z score tests at P < .05 cross-validation demonstrated an average misclassification rate of approximately 4.25%, and range over the 2,394 gray matter pixels was 27.66% to 0.11%. At P < .01 parametric Z score cross-validation false positives were 0.26% and ranged from 6.65% to 0% false positives. The non-parametric Key Institute's t-max statistic at P < .05 had an average misclassification error rate of 7.64% and ranged from 43.37% to 0.04% false positives. The nonparametric t-max at P < .01 had an average misclassification rate

  14. Quantum tomography enhanced through parametric amplification

    NASA Astrophysics Data System (ADS)

    Knyazev, E.; Spasibko, K. Yu; Chekhova, M. V.; Khalili, F. Ya

    2018-01-01

    Quantum tomography is the standard method of reconstructing the Wigner function of quantum states of light by means of balanced homodyne detection. The reconstruction quality strongly depends on the photodetectors quantum efficiency and other losses in the measurement setup. In this article we analyze in detail a protocol of enhanced quantum tomography, proposed by Leonhardt and Paul [1] which allows one to reduce the degrading effect of detection losses. It is based on phase-sensitive parametric amplification, with the phase of the amplified quadrature being scanned synchronously with the local oscillator phase. Although with sufficiently strong amplification the protocol enables overcoming any detection inefficiency, it was so far not implemented in the experiment, probably due to the losses in the amplifier. Here we discuss a possible proof-of-principle experiment with a traveling-wave parametric amplifier. We show that with the state-of-the-art optical elements, the protocol enables high fidelity tomographic reconstruction of bright non-classical states of light. We consider two examples: bright squeezed vacuum and squeezed single-photon state, with the latter being a non-Gaussian state and both strongly affected by the losses.

  15. Terahertz parametric sources and imaging applications

    NASA Astrophysics Data System (ADS)

    Yamashita, M.; Ogawa, Y.; Otani, C.; Kawase, K.

    2005-12-01

    We have studied the generation of terahertz (THz) waves by optical parametric processes based on laser light scattering from the polariton mode of nonlinear crystals. Using parametric oscillation of LiNbO 3 or MgO-doped LiNbO 3 crystal pumped by a nano-second Q-switched Nd:YAG laser, we have realized a widely tunable coherent THz-wave sources with a simple configuration. We report the detailed characteristics of the oscillation and the radiation including tunability, spatial and temporal coherency, uni directivity, and efficiency. A Fourier transform limited THz-wave spectrum narrowing was achieved by introducing the injection seeding method. Further, we have developed a spectroscopic THz imaging system using a TPO, which allows detection and identification of drugs concealed in envelopes, by introducing the component spatial pattern analysis. Several images of the envelope are recorded at different THz frequencies and then processed. The final result is an image that reveals what substances are present in the envelope, in what quantity, and how they are distributed across the envelope area. The example presented here shows the identification of three drugs, two of which illegal, while one is an over-the-counter drug.

  16. Parametric instability in the high power era of Advanced LIGO

    NASA Astrophysics Data System (ADS)

    Hardwick, Terra; Blair, Carl; Kennedy, Ross; Evans, Matthew; Fritschel, Peter; LIGO Virgo Scientific Collaboration

    2017-01-01

    After the first direct detections of gravitational waves, Advanced LIGO aims to increase its detection rate during the upcoming science runs through a series of detector improvements, including increased optical power. Higher circulating power increases the likelihood for three-mode parametric instabilities (PIs), in which mechanical modes of the mirrors scatter light into higher-order optical modes in the cavity and the resulting optical modes reinforce the mechanical modes via radiation pressure. Currently, LIGO uses two PI mitigation methods: thermal tuning to change the cavity g-factor and effectively decrease the frequency overlap between mechanical and optical modes, and active damping of mechanical modes with electrostatic actuation. While the combined methods provide stability at the current operating power, there is evidence that these will be insufficient for the next planned power increase; future suppression methods including acoustic mode dampers and dynamic g-factor modulation are discussed.

  17. Nearly noiseless amplification of microwave signals with a Josephson parametric amplifier

    NASA Astrophysics Data System (ADS)

    Castellanos-Beltran, Manuel

    2009-03-01

    A degenerate parametric amplifier transforms an incident coherent state by amplifying one of its quadrature components while deamplifying the other. This transformation, when performed by an ideal parametric amplifier, is completely deterministic and reversible; therefore the amplifier in principle can be noiseless. We attempt to realize a noiseless amplifier of this type at microwave frequencies with a Josephson parametric amplifier (JPA). To this end, we have built a superconducting microwave cavity containing many dc-SQUIDs. This arrangement creates a non-linear medium in a cavity and it is closely analogous to an optical parametric amplifier. In my talk, I will describe the current performance of this circuit, where I show I can amplify signals with less added noise than a quantum-limited amplifier that amplifies both quadratures. In addition, the JPA also squeezes the electromagnetic vacuum fluctuations by 10 dB. Finally, I will discuss our effort to put two such amplifiers in series in order to undo the first stage of squeezing with a second stage of amplification, demonstrating that the amplification process is truly reversible.[4pt] M. A. Castellanos-Beltran, K. D. Irwin, G. C. Hilton, L. R. Vale and K. W. Lehnert, Nature Physics, published on line, http://dx.doi.org/10.1038/nphys1090 (2008).

  18. A robust optical parametric oscillator and receiver telescope for differential absorption lidar of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Robinson, Iain; Jack, James W.; Rae, Cameron F.; Moncrieff, John B.

    2015-10-01

    We report the development of a differential absorption lidar instrument (DIAL) designed and built specifically for the measurement of anthropogenic greenhouse gases in the atmosphere. The DIAL is integrated into a commercial astronomical telescope to provide high-quality receiver optics and enable automated scanning for three-dimensional lidar acquisition. The instrument is portable and can be set up within a few hours in the field. The laser source is a pulsed optical parametric oscillator (OPO) which outputs light at a wavelength tunable near 1.6 μm. This wavelength region, which is also used in telecommunications devices, provides access to absorption lines in both carbon dioxide at 1573 nm and methane at 1646 nm. To achieve the critical temperature stability required for a laserbased field instrument the four-mirror OPO cavity is machined from a single aluminium block. A piezoactuator adjusts the cavity length to achieve resonance and this is maintained over temperature changes through the use of a feedback loop. The laser output is continuously monitored with pyroelectric detectors and a custom-built wavemeter. The OPO is injection seeded by a temperature-stabilized distributed feedback laser diode (DFB-LD) with a wavelength locked to the absorption line centre (on-line) using a gas cell containing pure carbon dioxide. A second DFB-LD is tuned to a nearby wavelength (off-line) to provide the reference required for differential absorption measurements. A similar system has been designed and built to provide the injection seeding wavelengths for methane. The system integrates the DFB-LDs, drivers, locking electronics, gas cell and balanced photodetectors. The results of test measurements of carbon dioxide are presented and the development of the system is discussed, including the adaptation required for the measurement of methane.

  19. 520-µJ mid-infrared femtosecond laser at 2.8 µm by 1-kHz KTA optical parametric amplifier

    NASA Astrophysics Data System (ADS)

    He, Huijun; Wang, Zhaohua; Hu, Chenyang; Jiang, Jianwang; Qin, Shuang; He, Peng; Zhang, Ninghua; Yang, Peilong; Li, Zhiyuan; Wei, Zhiyi

    2018-02-01

    We report on a 520-µJ, 1-kHz mid-infrared femtosecond optical parametric amplifier system driven by a Ti:sapphire laser system. The seeding signal was generated from white-light continuum in YAG plate and then amplified in four non-collinear amplification stages and the idler was obtained in the last stage with central wavelength at 2.8 µm and bandwidth of 525 nm. To maximize the bandwidth of the idler, a theoretical method was developed to give an optimum non-collinear angle and estimate the conversion efficiency and output spectrum. As an experimental result, laser pulse energy up to 1.8 mJ for signal wave and 520 µJ for idler wave were obtained in the last stage under 10-mJ pump energy, corresponding to a pump-to-idler conversion efficiency of 5.2%, which meets well with the numerical calculation.

  20. Quantum spatial propagation of squeezed light in a degenerate parametric amplifier

    NASA Technical Reports Server (NTRS)

    Deutsch, Ivan H.; Garrison, John C.

    1992-01-01

    Differential equations which describe the steady state spatial evolution of nonclassical light are established using standard quantum field theoretic techniques. A Schroedinger equation for the state vector of the optical field is derived using the quantum analog of the slowly varying envelope approximation (SVEA). The steady state solutions are those that satisfy the time independent Schroedinger equation. The resulting eigenvalue problem then leads to the spatial propagation equations. For the degenerate parametric amplifier this method shows that the squeezing parameter obey nonlinear differential equations coupled by the amplifier gain and phase mismatch. The solution to these differential equations is equivalent to one obtained from the classical three wave mixing steady state solution to the parametric amplifier with a nondepleted pump.

  1. Quasi-phase-matched χ(3 )-parametric interactions in sinusoidally tapered waveguides

    NASA Astrophysics Data System (ADS)

    Saleh, Mohammed F.

    2018-01-01

    In this article, I show how periodically tapered waveguides can be employed as efficient quasi-phase-matching schemes for four-wave mixing parametric processes in third-order nonlinear materials. As an example, a thorough study of enhancing third-harmonic generation in sinusoidally tapered fibers has been conducted. The quasi-phase-matching condition has been obtained for nonlinear parametric interactions in these structures using Fourier-series analysis. The dependencies of the conversion efficiency of the third harmonic on the modulation amplitude, tapering period, longitudinal-propagation direction, and pump wavelength have been studied. In comparison to uniform waveguides, the conversion efficiency has been enhanced by orders of magnitudes. I envisage that this work will have a great impact in the field of guided nonlinear optics using centrosymmetric materials.

  2. 1 kHz 3.3 μm Nd:YAG KTiOAsO₄ optical parametric oscillator system for laser ultrasound excitation of carbon-fiber-reinforced plastics.

    PubMed

    Puncken, Oliver; Gandara, David Mendoza; Damjanic, Marcin; Mahnke, Peter; Bergmann, Ralf B; Kalms, Michael; Peuser, Peter; Wessels, Peter; Neumann, Jörg; Schnars, Ulf

    2016-02-20

    We present a new laser prototype for laser ultrasonics excitation. The fundamental wavelength of a Q-switched Nd:YAG laser with a repetition rate of 1 kHz is converted to 3.3 μm with a KTiOAsO4 optical parametric oscillator. The achieved pulse energy at 3.3 μm is 1.7 mJ, and the pulse duration at the fundamental wavelength of 1.06 μm has been measured to be 21 ns. The ultrasonic excitation efficiency is about 3.5 times better compared to the application of state-of-the-art CO2 lasers.

  3. Atmospheric boundary layer CO2 remote sensing with a direct detection LIDAR instrument based on a widely tunable optical parametric source.

    PubMed

    Cadiou, Erwan; Mammez, Dominique; Dherbecourt, Jean-Baptiste; Gorju, Guillaume; Pelon, Jacques; Melkonian, Jean-Michel; Godard, Antoine; Raybaut, Myriam

    2017-10-15

    We report on the capability of a direct detection differential absorption lidar (DIAL) for range resolved and integrated path (IPDIAL) remote sensing of CO 2 in the atmospheric boundary layer (ABL). The laser source is an amplified nested cavity optical parametric oscillator (NesCOPO) emitting approximately 8 mJ at the two measurement wavelengths selected near 2050 nm. Direct detection atmospheric measurements are taken from the ground using a 30 Hz frequency switching between emitted wavelengths. Results show that comparable precision measurements are achieved in DIAL and IPDIAL modes (not better than a few ppm) on high SNR targets such as near range ABL aerosol and clouds, respectively. Instrumental limitations are analyzed and degradation due to cloud scattering variability is discussed to explain observed DIAL and IPDIAL limitations.

  4. Potassium titanyl arsenate based cascaded optical parametric oscillator emit at 2.5 µm derived by neodymium-doped yttrium lithium fluoride laser

    NASA Astrophysics Data System (ADS)

    Duan, Yanmin; Zhang, Jing; Guo, Junhong; Zhu, Haiyong; Zhang, Yongchang; Xu, Changwen; Wang, Hongyan; Zhang, Yaoju

    2018-04-01

    We reported a potassium titanyl arsenate (KTA) based cascaded optical parametric oscillator (OPO). The secondary OPO signal light at 2.5 µm was obtained with two OPO processes in one non-critical phase matching cut KTA crystal. This cascaded OPO was driven by a Q-switched neodymium-doped yttrium lithium fluoride (Nd:YLF) laser at 1047 nm. Making full use of the negative thermal lens effect and long upper level fluorescence lifetime of Nd:YLF, signal power of 605 mW at 2503 nm was achieved with a pulse repetition frequency of 15 kHz and an incident diode pump power of 9.7 W. Therefore, the cascaded OPO derived by Q-switched Nd:YLF laser could provide high peak power pulsed laser emission in mid-infrared band.

  5. Femtosecond optical parametric amplification in BBO and KTA driven by a Ti:sapphire laser for LIDT testing and diagnostic development

    NASA Astrophysics Data System (ADS)

    Meadows, Alexander R.; Cupal, Josef; Hříbek, Petr; Durák, Michal; Kramer, Daniel; Rus, Bedřich

    2017-05-01

    We present the design of a collinear femtosecond optical parametric amplification (OPA) system producing a tunable output at wavelengths between 1030 nm and 1080 nm from a Ti:Sapphire pump laser at a wavelength of 795 nm. Generation of a supercontinuum seed pulse is followed by one stage of amplification in Beta Barium Borate (BBO) and two stages of amplification in Potassium Titanyle Arsenate (KTA), resulting in a 225 μJ output pulse with a duration of 90 fs. The output of the system has been measured by self-referenced spectral interferometry to yield the complete spectrum and spectral phase of the pulse. When compared to KTP, the greater transparency of KTA in the spectral range from 3 - 4 μm allows for reduced idler absorption and enhanced gain from the OPA process when it is pumped by the fundamental frequency of a Ti:sapphire laser. In turn, the use of the Ti:sapphire fundamental at 795 nm as a pump improves the efficiency with which light can be converted to wavelengths between 1030 nm and 1080 nm and subsequently used to test components for Nd-based laser systems. This OPA system is operated at 1 kHz for diagnostic development and laser-induced damage threshold testing of optical components for the ELI-Beamlines project.

  6. Toward a compact fibered squeezing parametric source.

    PubMed

    Brieussel, Alexandre; Ott, Konstantin; Joos, Maxime; Treps, Nicolas; Fabre, Claude

    2018-03-15

    In this work, we investigate three different compact fibered systems generating vacuum squeezing that involve optical cavities limited by the end surface of a fiber and by a curved mirror and containing a thin parametric crystal. These systems have the advantage to couple squeezed states directly to a fiber, allowing the user to benefit from the flexibility of fibers in the use of squeezing. Three types of fibers are investigated: standard single-mode fibers, photonic-crystal large-mode-area single-mode fibers, and short multimode fibers taped to a single-mode fiber. The observed squeezing is modest (-0.56  dB, -0.9  dB, -1  dB), but these experiments open the way for miniaturized squeezing devices that could be a very interesting advantage in scaling up quantum systems for quantum processing, opening new perspectives in the domain of integrated quantum optics.

  7. Generation of terahertz from ZnGeP2 crystal and its application to record the time-resolved photoacoustic spectra of nitromethane

    NASA Astrophysics Data System (ADS)

    Rao, K. S.; Ganesh, D.; Chaudhary, A. K.

    2018-07-01

    This paper reports the generation of THz radiation through the optical rectification process from type-I cut Zinc germanium phosphate (ZnGeP2or ZGP) crystal using optical parametric amplifier pulses (tunable between 1.15-1.6 μm range, at 60 fs pulse duration and 1 kHz repetition rate) as pump wavelengths at an average power of 50 mW. Also, we have ascertained the conversion efficiency of the generated THz signal, which is of the order of 0.62% at 1.5 THz. Further, the generated radiation is employed for the recording of absorption bands (in terms of PA spectra) of nitromethane and methanol vapor at room temperature using bandpass filters having central frequencies of 0.5 and 1.5 THz. In addition, we have employed the UV-266 nm as an excitation wavelength to record the time domain photoacoustic (PA) spectra of nitromethane (CH3NO2). In case of UV and THz radiations, the excitation mechanisms follow strong electronic (π∗ ← n) and weak vibrational-rotational due to ultrafast transition, respectively. In case of UV-266 nm the characteristic PA spectra has been also presented as a function of vapor pressure and data acquisition time with two different PA cells. The current study reveals the effect of the nanoseconds and the ultrafast pulses on some of the common excited acoustic modes (due to similar functional group), which follow two different types of excitation mechanism.

  8. Multiple Frequency Parametric Sonar

    DTIC Science & Technology

    2015-09-28

    300003 1 MULTIPLE FREQUENCY PARAMETRIC SONAR STATEMENT OF GOVERNMENT INTEREST [0001] The invention described herein may be manufactured and...a method for increasing the bandwidth of a parametric sonar system by using multiple primary frequencies rather than only two primary frequencies...2) Description of Prior Art [0004] Parametric sonar generates narrow beams at low frequencies by projecting sound at two distinct primary

  9. Quadrature demultiplexing using a degenerate vector parametric amplifier.

    PubMed

    Lorences-Riesgo, Abel; Liu, Lan; Olsson, Samuel L I; Malik, Rohit; Kumpera, Aleš; Lundström, Carl; Radic, Stojan; Karlsson, Magnus; Andrekson, Peter A

    2014-12-01

    We report on quadrature demultiplexing of a quadrature phase-shift keying (QPSK) signal into two cross-polarized binary phase-shift keying (BPSK) signals with negligible penalty at bit-error rate (BER) equal to 10(-9). The all-optical quadrature demultiplexing is achieved using a degenerate vector parametric amplifier operating in phase-insensitive mode. We also propose and demonstrate the use of a novel and simple phase-locked loop (PLL) scheme based on detecting the envelope of one of the signals after demultiplexing in order to achieve stable quadrature decomposition.

  10. Widely tunable optical parametric oscillation in a Kerr microresonator.

    PubMed

    Sayson, Noel Lito B; Webb, Karen E; Coen, Stéphane; Erkintalo, Miro; Murdoch, Stuart G

    2017-12-15

    We report on the first experimental demonstration of widely tunable parametric sideband generation in a Kerr microresonator. Specifically, by pumping a silica microsphere in the normal dispersion regime, we achieve the generation of phase-matched four-wave mixing sidebands at large frequency detunings from the pump. Thanks to the role of higher-order dispersion in enabling phase matching, small variations of the pump wavelength translate into very large and controllable changes in the wavelengths of the generated sidebands: we experimentally demonstrate over 720 nm of tunability using a low-power continuous-wave pump laser in the C-band. We also derive simple theoretical predictions for the phase-matched sideband frequencies and discuss the predictions in light of the discrete cavity resonance frequencies. Our experimentally measured sideband wavelengths are in very good agreement with theoretical predictions obtained from our simple phase-matching analysis.

  11. On the suitability of fibre optical parametric amplifiers for use in all-optical agile photonic networks

    NASA Astrophysics Data System (ADS)

    Gryspolakis, Nikolaos

    The objective of this thesis is to investigate the suitability of fibre optical parametric amplifiers (FOPAs) for use in multi-channel, dynamic networks. First, we investigate their quasi-static behaviour in such an environment. We study the behaviour of a FOPA under realistic conditions and we examine the impact on the gain spectrum of channel addition for several different operating conditions and regimes. In particular, we examine the impact of surviving channel(s) position, input power and channel spacing. We see how these parameters affect the gain tilt as well as its dynamic characteristics, namely the generation of under or over-shoots at the transition point, possible dependence of rise and fall times on any of the aforementioned parameters and how the gain excursions depend on those parameters. For these studies we assume continuous wave operation for all signals. We observe that the gain spectrum changes are a function of the position and the spacing of the channels. We also find that the gain excursion can reach several dBs (up to 5 dB) in the case of channel add/drop and are heavily dependent on the position of the surviving channels. The channels located in the middle of the transmission band are more prone to channel add/drop-induced gain changes. Moreover, we investigate for the first time the FOPA dynamic behaviour in a packet switching scenario. This part of the study assumes that all but one channels normally vary in a packet-switched fashion. The remaining channel (probe channel) is expected to undergo gain variations due to the perturbation of the system experienced by the other channels. Furthermore, we consider several different scenarios for which the channels spacing, per channel input power (PCIP), variance of the power fluctuation and position of the probe channel will change. We find that when the FOPA operates near saturation the target gain is not achieved more than 50% of the time while the peak-to-peak gain excursions can exceed 1 d

  12. Theory of parametrically amplified electron-phonon superconductivity

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Babadi, Mehrtash; Knap, Michael; Martin, Ivar

    2017-07-01

    Ultrafast optical manipulation of ordered phases in strongly correlated materials is a topic of significant theoretical, experimental, and technological interest. Inspired by a recent experiment on light-induced superconductivity in fullerenes [M. Mitrano et al., Nature (London) 530, 461 (2016)], we develop a comprehensive theory of light-induced superconductivity in driven electron-phonon systemswith lattice nonlinearities. In analogy with the operation of parametric amplifiers, we show how the interplay between the external drive and lattice nonlinearities lead to significantly enhanced effective electron-phonon couplings. We provide a detailed and unbiased study of the nonequilibrium dynamics of the driven system using the real-time Green's functionmore » technique. To this end, we develop a Floquet generalization of the Migdal-Eliashberg theory and derive a numerically tractable set of quantum Floquet-Boltzmann kinetic equations for the coupled electron-phonon system. We study the role of parametric phonon generation and electronic heating in destroying the transient superconducting state. Finally, we predict the transient formation of electronic Floquet bands in time-and angle-resolved photoemission spectroscopy experiments as a consequence of the proposed mechanism.« less

  13. Tunable terahertz waves from 4-dimethylamino-N‧-methyl-4‧-stibazolium tosylate pumped with dual-wavelength injection-seeded optical parametric generation

    NASA Astrophysics Data System (ADS)

    Tokizane, Yu; Nawata, Kouji; Han, Zhengli; Koyama, Mio; Notake, Takashi; Takida, Yuma; Minamide, Hiroaki

    2017-02-01

    We developed a widely tunable terahertz (THz)-wave source covering the sub-THz frequency by difference frequency generation using a 4-dimethylamino-N‧-methyl-4‧-stibazolium tosylate (DAST) crystal. Near-infrared waves generated by dual-wavelength injection-seeded β-BaB2O4 optical parametric generation (is-BBO-OPG) were used for pumping the DAST crystal, which had separated wavelengths in the spectrum with a difference frequency of sub-THz. Furthermore, the non-collinear phase-matching condition was designed to compensate the walk-off effect of the BBO crystal. Consequently, tunable THz-waves from 0.3 to 4 THz were generated by tuning the wavelength of one of the seeding beams. The generated sub-THz-waves were monochromatic (dν < 33 GHz) with a maximum energy of 80 pJ at 0.65 THz.

  14. Widely tunable eye-safe laser by a passively Q-switched photonic crystal fiber laser and an external-cavity optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Chang, H. L.; Zhuang, W. Z.; Huang, W. C.; Huang, J. Y.; Huang, K. F.; Chen, Y. F.

    2011-09-01

    We report on a widely tunable passively Q-switched photonic crystal fiber (PCF) laser with wavelength tuning range up to 80 nm. The PCF laser utilizes an AlGaInAs quantum well/barrier structure as a saturable absorber and incorporates an external-cavity optical parametric oscillator (OPO) to achieve wavelength conversion. Under a pump power of 13.1 W at 976 nm, the PCF laser generated 1029-nm radiation with maximum output energy of 750 μJ and was incident into an external-cavity OPO. The output energy and peak power of signal wave was found to be 138 μJ and 19 kW, respectively. By tuning the temperature of nonlinear crystal, periodically poled lithium niobate (PPLN), in the OPO, the signal wavelength in eye-safe regime from 1513 to 1593 nm was obtained.

  15. Rephasing invariant parametrization of flavor mixing

    NASA Astrophysics Data System (ADS)

    Lee, Tae-Hun

    A new rephasing invariant parametrization for the 3 x 3 CKM matrix, called (x, y) parametrization, is introduced and the properties and applications of the parametrization are discussed. The overall phase condition leads this parametrization to have only six rephsing invariant parameters and two constraints. Its simplicity and regularity become apparent when it is applied to the one-loop RGE (renormalization group equations) for the Yukawa couplings. The implications of this parametrization for unification of the Yukawa couplings are also explored.

  16. Ultra-wideband and high-gain parametric amplification in telecom wavelengths with an optimally mode-matched PPLN waveguide.

    PubMed

    Sua, Yong Meng; Chen, Jia-Yang; Huang, Yu-Ping

    2018-06-15

    We report a wideband optical parametric amplification (OPA) over 14 THz covering telecom S, C, and L bands with observed maximum parametric gain of 38.3 dB. The OPA is realized through cascaded second-harmonic generation and difference-frequency generation (cSHG-DFG) in a 2 cm periodically poled LiNbO 3 (PPLN) waveguide. With tailored cross section geometry, the waveguide is optimally mode matched for efficient cascaded nonlinear wave mixing. We also identify and study the effect of competing nonlinear processes in this cSHG-DFG configuration.

  17. Parametrization and calibration of a quasi-analytical algorithm for tropical eutrophic waters

    NASA Astrophysics Data System (ADS)

    Watanabe, Fernanda; Mishra, Deepak R.; Astuti, Ike; Rodrigues, Thanan; Alcântara, Enner; Imai, Nilton N.; Barbosa, Cláudio

    2016-11-01

    Quasi-analytical algorithm (QAA) was designed to derive the inherent optical properties (IOPs) of water bodies from above-surface remote sensing reflectance (Rrs). Several variants of QAA have been developed for environments with different bio-optical characteristics. However, most variants of QAA suffer from moderate to high negative IOP prediction when applied to tropical eutrophic waters. This research is aimed at parametrizing a QAA for tropical eutrophic water dominated by cyanobacteria. The alterations proposed in the algorithm yielded accurate absorption coefficients and chlorophyll-a (Chl-a) concentration. The main changes accomplished were the selection of wavelengths representative of the optically relevant constituents (ORCs) and calibration of values directly associated with the pigments and detritus plus colored dissolved organic material (CDM) absorption coefficients. The re-parametrized QAA eliminated the retrieval of negative values, commonly identified in other variants of QAA. The calibrated model generated a normalized root mean square error (NRMSE) of 21.88% and a mean absolute percentage error (MAPE) of 28.27% for at(λ), where the largest errors were found at 412 nm and 620 nm. Estimated NRMSE for aCDM(λ) was 18.86% with a MAPE of 31.17%. A NRMSE of 22.94% and a MAPE of 60.08% were obtained for aφ(λ). Estimated aφ(665) and aφ(709) was used to predict Chl-a concentration. aφ(665) derived from QAA for Barra Bonita Hydroelectric Reservoir (QAA_BBHR) was able to predict Chl-a accurately, with a NRMSE of 11.3% and MAPE of 38.5%. The performance of the Chl-a model was comparable to some of the most widely used empirical algorithms such as 2-band, 3-band, and the normalized difference chlorophyll index (NDCI). The new QAA was parametrized based on the band configuration of MEdium Resolution Imaging Spectrometer (MERIS), Sentinel-2A and 3A and can be readily scaled-up for spatio-temporal monitoring of IOPs in tropical waters.

  18. High repetition rate tunable femtosecond pulses and broadband amplification from fiber laser pumped parametric amplifier.

    PubMed

    Andersen, T V; Schmidt, O; Bruchmann, C; Limpert, J; Aguergaray, C; Cormier, E; Tünnermann, A

    2006-05-29

    We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.

  19. Combined non-parametric and parametric approach for identification of time-variant systems

    NASA Astrophysics Data System (ADS)

    Dziedziech, Kajetan; Czop, Piotr; Staszewski, Wieslaw J.; Uhl, Tadeusz

    2018-03-01

    Identification of systems, structures and machines with variable physical parameters is a challenging task especially when time-varying vibration modes are involved. The paper proposes a new combined, two-step - i.e. non-parametric and parametric - modelling approach in order to determine time-varying vibration modes based on input-output measurements. Single-degree-of-freedom (SDOF) vibration modes from multi-degree-of-freedom (MDOF) non-parametric system representation are extracted in the first step with the use of time-frequency wavelet-based filters. The second step involves time-varying parametric representation of extracted modes with the use of recursive linear autoregressive-moving-average with exogenous inputs (ARMAX) models. The combined approach is demonstrated using system identification analysis based on the experimental mass-varying MDOF frame-like structure subjected to random excitation. The results show that the proposed combined method correctly captures the dynamics of the analysed structure, using minimum a priori information on the model.

  20. Tunable femtosecond near-infrared source based on a Yb:LYSO-laser-pumped optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Wen-Long, Tian; Zhao-Hua, Wang; Jiang-Feng, Zhu; Zhi-Yi, Wei

    2016-01-01

    We demonstrate a widely tunable near-infrared source from 767 nm to 874 nm generated by the intracavity second harmonic generation (SHG) in an optical parametric oscillator pumped by a Yb:LYSO solid-state laser. The home-made Yb:LYSO oscillator centered at 1035 nm delivers an average power of 2 W and a pulse duration as short as 351 fs. Two MgO doped periodically poled lithium niobates (MgO:PPLN) with grating periods of 28.5-31.5 μm in steps of 0.5 μm and 19.5-21.3 μm in steps of 0.2 μm are used for the OPO and intracavity SHG, respectively. The maximum average output power of 180 mW at 798 nm was obtained and the output pulses have pulse duration of 313 fs at 792 nm if a sech2-pulse shape was assumed. In addition, tunable signal femtosecond pulses from 1428 nm to 1763 nm are also realized with the maximum average power of 355 mW at 1628 nm. Project supported by the National Key Basic Research Program of China (Grant No. 2013CB922402), the National Key Scientific Instruments Development Program of China (Grant No. 2012YQ120047), the National Natural Science Foundation of China (Grant Nos. 61205130 and 11174361), and the Key Deployment Project of Chinese Academy of Sciences (Grant No. KJZD-EW-L11-03).

  1. Compact, passively Q-switched, all-solid-state master oscillator-power amplifier-optical parametric oscillator (MOPA-OPO) system pumped by a fiber-coupled diode laser generating high-brightness, tunable, ultraviolet radiation.

    PubMed

    Peuser, Peter; Platz, Willi; Fix, Andreas; Ehret, Gerhard; Meister, Alexander; Haag, Matthias; Zolichowski, Paul

    2009-07-01

    We report on a compact, tunable ultraviolet laser system that consists of an optical parametric oscillator (OPO) and a longitudinally diode-pumped Nd:YAG master oscillator-power amplifier (MOPA). The pump energy for the whole laser system is supplied via a single delivery fiber. Nanosecond pulses are produced by an oscillator that is passively Q-switched by a Cr(4+):YAG crystal. The OPO is pumped by the second harmonic of the Nd:YAG MOPA. Continuously tunable radiation is generated by an intracavity sum-frequency mixing process within the OPO in the range of 245-260 nm with high beam quality. Maximum pulse energies of 1.2 mJ were achieved, which correspond to an optical efficiency of 3.75%, relating to the pulse energy of the MOPA at 1064 nm.

  2. Parametrizing the Reionization History with the Redshift Midpoint, Duration, and Asymmetry

    NASA Astrophysics Data System (ADS)

    Trac, Hy

    2018-05-01

    A new parametrization of the reionization history is presented to facilitate robust comparisons between different observations and with theory. The evolution of the ionization fraction with redshift can be effectively captured by specifying the midpoint, duration, and asymmetry parameters. Lagrange interpolating functions are then used to construct analytical curves that exactly fit corresponding ionization points. The shape parametrizations are excellent matches to theoretical results from radiation-hydrodynamic simulations. The comparative differences for reionization observables are: ionization fraction | {{Δ }}{x}{{i}}| ≲ 0.03, 21 cm brightness temperature | {{Δ }}{T}{{b}}| ≲ 0.7 {mK}, Thomson optical depth | {{Δ }}τ | ≲ 0.001, and patchy kinetic Sunyaev–Zel’dovich angular power | {{Δ }}{D}{\\ell }| ≲ 0.1 μ {{{K}}}2. This accurate and flexible approach will allow parameter-space studies and self-consistent constraints on the reionization history from 21 cm, cosmic microwave background (CMB), and high-redshift galaxies and quasars.

  3. Parametric Cooling of Ultracold Atoms

    NASA Astrophysics Data System (ADS)

    Boguslawski, Matthew; Bharath, H. M.; Barrios, Maryrose; Chapman, Michael

    2017-04-01

    An oscillator is characterized by a restoring force which determines the natural frequency at which oscillations occur. The amplitude and phase-noise of these oscillations can be amplified or squeezed by modulating the magnitude of this force (e.g. the stiffness of the spring) at twice the natural frequency. This is parametric excitation; a long-studied phenomena in both the classical and quantum regimes. Parametric cooling, or the parametric squeezing of thermo-mechanical noise in oscillators has been studied in micro-mechanical oscillators and trapped ions. We study parametric cooling in ultracold atoms. This method shows a modest reduction of the variance of atomic momenta, and can be easily employed with pre-existing controls in many experiments. Parametric cooling is comparable to delta-kicked cooling, sharing similar limitations. We expect this cooling to find utility in microgravity experiments where the experiment duration is limited by atomic free expansion.

  4. Spectral and energy characteristics of four-photon parametric scattering in sodium vapor

    NASA Astrophysics Data System (ADS)

    Vaicaitis, V.; Ignatavicius, M.; Kudriashov, V. A.; Pimenov, Iu. N.; Jakyte, R.

    1987-04-01

    Consideration is given to processes of four-photon interaction upon two-photon resonance excitation of the 3d level of sodium by two-frequency radiation from a monopulse picosecond YAG:Nd laser with frequency doubling and an optical parametric oscillator utilizing KDP crystrals. The spatial and frequency spectra of the four-photon parametric scattering (FPS) are recorded and studied at different sodium vapor concentrations (10 to the 15th to 10 to the 17th/cu cm) and upon both collinear and noncollinear excitation. It is shown that the observed conical structure of the FPS radiation can be interpreted from an analysis of the realization of the frequency and spatial phase-matching conditions. The dependences of the FPS radiation intensity on the exciting radiation intensity, the sodium vapor concentration, and the mismatching of the exciting radiation from the two-photon resonance are obtained.

  5. Optical coherence tomography can assess skeletal muscle tissue from mouse models of muscular dystrophy by parametric imaging of the attenuation coefficient

    PubMed Central

    Klyen, Blake R.; Scolaro, Loretta; Shavlakadze, Tea; Grounds, Miranda D.; Sampson, David D.

    2014-01-01

    We present the assessment of ex vivo mouse muscle tissue by quantitative parametric imaging of the near-infrared attenuation coefficient µt using optical coherence tomography. The resulting values of the local total attenuation coefficient µt (mean ± standard error) from necrotic lesions in the dystrophic skeletal muscle tissue of mdx mice are higher (9.6 ± 0.3 mm−1) than regions from the same tissue containing only necrotic myofibers (7.0 ± 0.6 mm−1), and significantly higher than values from intact myofibers, whether from an adjacent region of the same sample (4.8 ± 0.3 mm−1) or from healthy tissue of the wild-type C57 mouse (3.9 ± 0.2 mm−1) used as a control. Our results suggest that the attenuation coefficient could be used as a quantitative means to identify necrotic lesions and assess skeletal muscle tissue in mouse models of human Duchenne muscular dystrophy. PMID:24761302

  6. Generic distortion model for metrology under optical microscopes

    NASA Astrophysics Data System (ADS)

    Liu, Xingjian; Li, Zhongwei; Zhong, Kai; Chao, YuhJin; Miraldo, Pedro; Shi, Yusheng

    2018-04-01

    For metrology under optical microscopes, lens distortion is the dominant source of error. Previous distortion models and correction methods mostly rely on the assumption that parametric distortion models require a priori knowledge of the microscopes' lens systems. However, because of the numerous optical elements in a microscope, distortions can be hardly represented by a simple parametric model. In this paper, a generic distortion model considering both symmetric and asymmetric distortions is developed. Such a model is obtained by using radial basis functions (RBFs) to interpolate the radius and distortion values of symmetric distortions (image coordinates and distortion rays for asymmetric distortions). An accurate and easy to implement distortion correction method is presented. With the proposed approach, quantitative measurement with better accuracy can be achieved, such as in Digital Image Correlation for deformation measurement when used with an optical microscope. The proposed technique is verified by both synthetic and real data experiments.

  7. A Parametric k-Means Algorithm

    PubMed Central

    Tarpey, Thaddeus

    2007-01-01

    Summary The k points that optimally represent a distribution (usually in terms of a squared error loss) are called the k principal points. This paper presents a computationally intensive method that automatically determines the principal points of a parametric distribution. Cluster means from the k-means algorithm are nonparametric estimators of principal points. A parametric k-means approach is introduced for estimating principal points by running the k-means algorithm on a very large simulated data set from a distribution whose parameters are estimated using maximum likelihood. Theoretical and simulation results are presented comparing the parametric k-means algorithm to the usual k-means algorithm and an example on determining sizes of gas masks is used to illustrate the parametric k-means algorithm. PMID:17917692

  8. High average power, widely tunable femtosecond laser source from red to mid-infrared based on an Yb-fiber-laser-pumped optical parametric oscillator.

    PubMed

    Gu, Chenglin; Hu, Minglie; Zhang, Limeng; Fan, Jintao; Song, Youjian; Wang, Chingyue; Reid, Derryck T

    2013-06-01

    We report on the highly efficient generation of widely tunable femtosecond pulses based on intracavity second harmonic generation (SHG) and sum frequency generation (SFG) in a MgO-doped periodically poled LiNbO(3) optical parametric oscillator (OPO), which is pumped by a Yb-doped large-mode-area photonics crystal fiber femtosecond laser. Red and near infrared from intracavity SHG and SFG and infrared signals were directly obtained from the OPO. A 2 mm β-BaB(2)O(4) is applied for Type I (oo → e) intracavity SHG and SFG, and then femtosecond laser pulses over 610 nm ~ 668 nm from SFG and 716 nm ~ 970 nm from SHG are obtained with high efficiency. In addition, the oscillator simultaneously generates signal and idler femtosecond pulses over 1450 nm ~ 2200 nm and 2250 nm ~ 4000 nm, respectively.

  9. Scalar limitations of diffractive optical elements

    NASA Technical Reports Server (NTRS)

    Johnson, Eric G.; Hochmuth, Diane; Moharam, M. G.; Pommet, Drew

    1993-01-01

    In this paper, scalar limitations of diffractive optic components are investigated using coupled wave analyses. Results are presented for linear phase gratings and fanout devices. In addition, a parametric curve is given which correlates feature size with scalar performance.

  10. Tunable, continuous-wave, ultraviolet source based on intracavity sum-frequency-generation in an optical parametric oscillator using BiB₃O₆.

    PubMed

    Devi, Kavita; Kumar, S Chaitanya; Ebrahim-Zadeh, M

    2013-10-21

    We report a continuous-wave (cw) source of tunable radiation across 333-345 nm in the ultraviolet (UV) using bismuth triborate, BiB₃O₆ (BIBO) as the nonlinear gain material. The source is based on internal sum-frequency-generation (SFG) in a cw singly-resonant optical parametric oscillator (OPO) pumped at 532 nm. The compact tunable source employs a 30-mm-long MgO:sPPLT crystal as the OPO gain medium and a 5-mm-long BIBO crystal for intracavity SFG of the signal and pump, providing up to 21.6 mW of UV power at 339.7 nm, with >15 mW over 64% of the SFG tuning range. The cw OPO is also tunable across 1158-1312 nm in the idler, delivering as much as 1.7 W at 1247 nm, with >1W over 65% of the tuning range. The UV output at maximum power exhibits passive power stability better than 3.4% rms and frequency stability of 193 GHz over more than one minute.

  11. Carrier-envelope phase-controlled quantum interference in optical poling.

    PubMed

    Adachi, Shunsuke; Kobayashi, Takayoshi

    2005-04-22

    We demonstrate the efficiency of the optical poling process that depends on the CE phase-controlled quantum interference. For the experiment we employed our noncollinear optical parametric amplifier system for the self-stabilization of the CE phase, with the f-to-2f spectral interferometry system to control the CE phase.

  12. Advanced Imaging Methods for Long-Baseline Optical Interferometry

    NASA Astrophysics Data System (ADS)

    Le Besnerais, G.; Lacour, S.; Mugnier, L. M.; Thiebaut, E.; Perrin, G.; Meimon, S.

    2008-11-01

    We address the data processing methods needed for imaging with a long baseline optical interferometer. We first describe parametric reconstruction approaches and adopt a general formulation of nonparametric image reconstruction as the solution of a constrained optimization problem. Within this framework, we present two recent reconstruction methods, Mira and Wisard, representative of the two generic approaches for dealing with the missing phase information. Mira is based on an implicit approach and a direct optimization of a Bayesian criterion while Wisard adopts a self-calibration approach and an alternate minimization scheme inspired from radio-astronomy. Both methods can handle various regularization criteria. We review commonly used regularization terms and introduce an original quadratic regularization called ldquosoft support constraintrdquo that favors the object compactness. It yields images of quality comparable to nonquadratic regularizations on the synthetic data we have processed. We then perform image reconstructions, both parametric and nonparametric, on astronomical data from the IOTA interferometer, and discuss the respective roles of parametric and nonparametric approaches for optical interferometric imaging.

  13. Offset-Free Gigahertz Midinfrared Frequency Comb Based on Optical Parametric Amplification in a Periodically Poled Lithium Niobate Waveguide

    NASA Astrophysics Data System (ADS)

    Mayer, A. S.; Phillips, C. R.; Langrock, C.; Klenner, A.; Johnson, A. R.; Luke, K.; Okawachi, Y.; Lipson, M.; Gaeta, A. L.; Fejer, M. M.; Keller, U.

    2016-11-01

    We report the generation of an optical-frequency comb in the midinfrared region with 1-GHz comb-line spacing and no offset with respect to absolute-zero frequency. This comb is tunable from 2.5 to 4.2 μ m and covers a critical spectral region for important environmental and industrial applications, such as molecular spectroscopy of trace gases. We obtain such a comb using a highly efficient frequency conversion of a near-infrared frequency comb. The latter is based on a compact diode-pumped semiconductor saturable absorber mirror-mode-locked ytterbium-doped calcium-aluminum gadolynate (Yb:CALGO) laser operating at 1 μ m . The frequency-conversion process is based on optical parametric amplification (OPA) in a periodically poled lithium niobate (PPLN) chip containing buried waveguides fabricated by reverse proton exchange. The laser with a repetition rate of 1 GHz is the only active element of the system. It provides the pump pulses for the OPA process as well as seed photons in the range of 1.4 - 1.8 μ m via supercontinuum generation in a silicon-nitride (Si3 N4 ) waveguide. Both the PPLN and Si3 N4 waveguides represent particularly suitable platforms for low-energy nonlinear interactions; they allow for mid-IR comb powers per comb line at the microwatt level and signal amplification levels up to 35 dB, with 2 orders of magnitude less pulse energy than reported in OPA systems using bulk devices. Based on numerical simulations, we explain how high amplification can be achieved at low energy using the interplay between mode confinement and a favorable group-velocity mismatch configuration where the mid-IR pulse moves at the same velocity as the pump.

  14. Parametric instabilities in resonantly-driven Bose–Einstein condensates

    NASA Astrophysics Data System (ADS)

    Lellouch, S.; Goldman, N.

    2018-04-01

    Shaking optical lattices in a resonant manner offers an efficient and versatile method to devise artificial gauge fields and topological band structures for ultracold atomic gases. This was recently demonstrated through the experimental realization of the Harper–Hofstadter model, which combined optical superlattices and resonant time-modulations. Adding inter-particle interactions to these engineered band systems is expected to lead to strongly-correlated states with topological features, such as fractional Chern insulators. However, the interplay between interactions and external time-periodic drives typically triggers violent instabilities and uncontrollable heating, hence potentially ruling out the possibility of accessing such intriguing states of matter in experiments. In this work, we study the early-stage parametric instabilities that occur in systems of resonantly-driven Bose–Einstein condensates in optical lattices. We apply and extend an approach based on Bogoliubov theory (Lellouch et al 2017 Phys. Rev. X 7 021015) to a variety of resonantly-driven band models, from a simple shaken Wannier–Stark ladder to the more intriguing driven-induced Harper–Hofstadter model. In particular, we provide ab initio numerical and analytical predictions for the stability properties of these topical models. This work sheds light on general features that could guide current experiments to stable regimes of operation.

  15. Parametric amplification of 100 fs mid-infrared pulses in ZnGeP2 driven by a Ho:YAG chirped-pulse amplifier.

    PubMed

    Kanai, Tsuneto; Malevich, Pavel; Kangaparambil, Sarayoo Sasidharan; Ishida, Kakuta; Mizui, Makoto; Yamanouchi, Kaoru; Hoogland, Heinar; Holzwarth, Ronald; Pugzlys, Audrius; Baltuska, Andrius

    2017-02-15

    We report on the parametric generation of 100 fs sub-6-cycle 40 μJ pulses with the center wavelength at 5.2 μm using a 1 ps 2.1 μm pump laser and a dispersion management scheme based on bulk material. Our optically synchronized amplifier chain consists of a Ho:YAG chirped-pulse amplifier and white-light-seeded optical parametric amplifiers providing simultaneous passive carrier-envelope phase locking of three ultrashort longwave pulses at the pump, signal, and idler wavelengths corresponding, respectively, to 2.1, 3.5, and 5.2 μm. We also demonstrate bandwidth enhancement and efficient control over nonlinear spectral phase in the regime of cascaded χ2 nonlinearity in ZnGeP2.

  16. Sub-nanosecond periodically poled lithium niobate optical parametric generator and amplifier pumped by an actively Q-switched diode-pumped Nd:YAG microlaser

    NASA Astrophysics Data System (ADS)

    Liu, L.; Wang, H. Y.; Ning, Y.; Shen, C.; Si, L.; Yang, Y.; Bao, Q. L.; Ren, G.

    2017-05-01

    A sub-nanosecond seeded optical parametric generator (OPG) based on magnesium oxide-doped periodically poled lithium niobate (MgO:PPLN) crystal is presented. Pumped by an actively Q-switched diode-pumped 1 kHz, 1064 nm, Nd:YAG microlaser and seeded with a low power distributed feedback (DFB) diode continuous-wave (CW) laser, the OPG generated an output energy of 41.4 µJ and 681 ps pulse duration for the signal at 1652.4 nm, achieving a quantum conversion efficiency of 61.2% and a slope efficiency of 41.8%. Signal tuning was achieved from 1651.0 to 1652.4 nm by tuning the seed-laser current. The FWHM of the signal spectrum was approximately from 35 nm to 0.5 nm by injection seed laser. The SHG doubled the frequency of OPG signal to produce a output energy of 12 µJ with the energy conversion efficiency of 29.0% and tunanble wavelength near 826 nm.

  17. Hyperbolic and semi-parametric models in finance

    NASA Astrophysics Data System (ADS)

    Bingham, N. H.; Kiesel, Rüdiger

    2001-02-01

    The benchmark Black-Scholes-Merton model of mathematical finance is parametric, based on the normal/Gaussian distribution. Its principal parametric competitor, the hyperbolic model of Barndorff-Nielsen, Eberlein and others, is briefly discussed. Our main theme is the use of semi-parametric models, incorporating the mean vector and covariance matrix as in the Markowitz approach, plus a non-parametric part, a scalar function incorporating features such as tail-decay. Implementation is also briefly discussed.

  18. Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving.

    PubMed

    Li, Jiaming; de Melo, Leonardo F; Luo, Le

    2017-03-30

    We present a cooling method for a cold Fermi gas by parametrically driving atomic motions in a crossed-beam optical dipole trap (ODT). Our method employs the anharmonicity of the ODT, in which the hotter atoms at the edge of the trap feel the anharmonic components of the trapping potential, while the colder atoms in the center of the trap feel the harmonic one. By modulating the trap depth with frequencies that are resonant with the anharmonic components, we selectively excite the hotter atoms out of the trap while keeping the colder atoms in the trap, generating parametric cooling. This experimental protocol starts with a magneto-optical trap (MOT) that is loaded by a Zeeman slower. The precooled atoms in the MOT are then transferred to an ODT, and a bias magnetic field is applied to create an interacting Fermi gas. We then lower the trapping potential to prepare a cold Fermi gas near the degenerate temperature. After that, we sweep the magnetic field to the noninteracting regime of the Fermi gas, in which the parametric cooling can be manifested by modulating the intensity of the optical trapping beams. We find that the parametric cooling effect strongly depends on the modulation frequencies and amplitudes. With the optimized frequency and amplitude, we measure the dependence of the cloud energy on the modulation time. We observe that the cloud energy is changed in an anisotropic way, where the energy of the axial direction is significantly reduced by parametric driving. The cooling effect is limited to the axial direction because the dominant anharmonicity of the crossed-beam ODT is along the axial direction. Finally, we propose to extend this protocol for the trapping potentials of large anharmonicity in all directions, which provides a promising scheme for cooling quantum gases using external driving.

  19. Parametric resonance in tunable superconducting cavities

    NASA Astrophysics Data System (ADS)

    Wustmann, Waltraut; Shumeiko, Vitaly

    2013-05-01

    We develop a theory of parametric resonance in tunable superconducting cavities. The nonlinearity introduced by the superconducting quantum interference device (SQUID) attached to the cavity and damping due to connection of the cavity to a transmission line are taken into consideration. We study in detail the nonlinear classical dynamics of the cavity field below and above the parametric threshold for the degenerate parametric resonance, featuring regimes of multistability and parametric radiation. We investigate the phase-sensitive amplification of external signals on resonance, as well as amplification of detuned signals, and relate the amplifier performance to that of linear parametric amplifiers. We also discuss applications of the device for dispersive qubit readout. Beyond the classical response of the cavity, we investigate small quantum fluctuations around the amplified classical signals. We evaluate the noise power spectrum both for the internal field in the cavity and the output field. Other quantum-statistical properties of the noise are addressed such as squeezing spectra, second-order coherence, and two-mode entanglement.

  20. Why preferring parametric forecasting to nonparametric methods?

    PubMed

    Jabot, Franck

    2015-05-07

    A recent series of papers by Charles T. Perretti and collaborators have shown that nonparametric forecasting methods can outperform parametric methods in noisy nonlinear systems. Such a situation can arise because of two main reasons: the instability of parametric inference procedures in chaotic systems which can lead to biased parameter estimates, and the discrepancy between the real system dynamics and the modeled one, a problem that Perretti and collaborators call "the true model myth". Should ecologists go on using the demanding parametric machinery when trying to forecast the dynamics of complex ecosystems? Or should they rely on the elegant nonparametric approach that appears so promising? It will be here argued that ecological forecasting based on parametric models presents two key comparative advantages over nonparametric approaches. First, the likelihood of parametric forecasting failure can be diagnosed thanks to simple Bayesian model checking procedures. Second, when parametric forecasting is diagnosed to be reliable, forecasting uncertainty can be estimated on virtual data generated with the fitted to data parametric model. In contrast, nonparametric techniques provide forecasts with unknown reliability. This argumentation is illustrated with the simple theta-logistic model that was previously used by Perretti and collaborators to make their point. It should convince ecologists to stick to standard parametric approaches, until methods have been developed to assess the reliability of nonparametric forecasting. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Towards terahertz detection and calibration through spontaneous parametric down-conversion in the terahertz idler-frequency range generated by a 795 nm diode laser system

    NASA Astrophysics Data System (ADS)

    Kornienko, Vladimir V.; Kitaeva, Galiya Kh.; Sedlmeir, Florian; Leuchs, Gerd; Schwefel, Harald G. L.

    2018-05-01

    We study a calibration scheme for terahertz wave nonlinear-optical detectors based on spontaneous parametric down-conversion. Contrary to the usual low wavelength pump in the green, we report here on the observation of spontaneous parametric down-conversion originating from an in-growth poled lithium niobate crystal pumped with a continuous wave 50 mW, 795 nm diode laser system, phase-matched to a terahertz frequency idler wave. Such a system is more compact and allows for longer poling periods as well as lower losses in the crystal. Filtering the pump radiation by a rubidium-87 vapor cell allowed the frequency-angular spectra to be obtained down to ˜0.5 THz or ˜1 nm shift from the pump radiation line. The presence of an amplified spontaneous emission "pedestal" in the diode laser radiation spectrum significantly hampers the observation of spontaneous parametric down-conversion spectra, in contrast to conventional narrowband gas lasers. Benefits of switching to longer pump wavelengths are pointed out, such as collinear optical-terahertz phase-matching in bulk crystals.

  2. Time-reversed wave mixing in nonlinear optics

    PubMed Central

    Zheng, Yuanlin; Ren, Huaijin; Wan, Wenjie; Chen, Xianfeng

    2013-01-01

    Time-reversal symmetry is important to optics. Optical processes can run in a forward or backward direction through time when such symmetry is preserved. In linear optics, a time-reversed process of laser emission can enable total absorption of coherent light fields inside an optical cavity of loss by time-reversing the original gain medium. Nonlinearity, however, can often destroy such symmetry in nonlinear optics, making it difficult to study time-reversal symmetry with nonlinear optical wave mixings. Here we demonstrate time-reversed wave mixings for optical second harmonic generation (SHG) and optical parametric amplification (OPA) by exploring this well-known but underappreciated symmetry in nonlinear optics. This allows us to observe the annihilation of coherent beams. Our study offers new avenues for flexible control in nonlinear optics and has potential applications in efficient wavelength conversion, all-optical computing. PMID:24247906

  3. Parametric instability of shaft with discs

    NASA Astrophysics Data System (ADS)

    Wahab, A. M. Abdul; Rasid, Z. A.; Abu, A.; Rudin, N. F. Mohd Noor

    2017-12-01

    The occurrence of resonance is a major criterion to be considered in the design of shaft. While force resonance occurs merely when the natural frequency of the rotor system equals speed of the shaft, parametric resonance or parametric instability can occur at excitation speed that is integral or sub-multiple of the frequency of the rotor. This makes the study on parametric resonance crucial. Parametric instability of a shaft system consisting of a shaft and disks has been investigated in this study. The finite element formulation of the Mathieu-Hill equation that represents the parametric instability problem of the shaft is developed based on Timoshenko’s beam theory and Nelson’s finite element method (FEM) model that considers the effect of torsional motion on such problem. The Bolotin’s method is used to determine the regions of instability and the Strut-Ince diagram. The validation works show that the results of this study are in close agreement to past results. It is found that a larger radius of disk will cause the shaft to become more unstable compared to smaller radius although both weights are similar. Furthermore, the effect of torsional motion on the parametric instability of the shaft is significant at higher rotating speed.

  4. Parametric nanomechanical amplification at very high frequency.

    PubMed

    Karabalin, R B; Feng, X L; Roukes, M L

    2009-09-01

    Parametric resonance and amplification are important in both fundamental physics and technological applications. Here we report very high frequency (VHF) parametric resonators and mechanical-domain amplifiers based on nanoelectromechanical systems (NEMS). Compound mechanical nanostructures patterned by multilayer, top-down nanofabrication are read out by a novel scheme that parametrically modulates longitudinal stress in doubly clamped beam NEMS resonators. Parametric pumping and signal amplification are demonstrated for VHF resonators up to approximately 130 MHz and provide useful enhancement of both resonance signal amplitude and quality factor. We find that Joule heating and reduced thermal conductance in these nanostructures ultimately impose an upper limit to device performance. We develop a theoretical model to account for both the parametric response and nonequilibrium thermal transport in these composite nanostructures. The results closely conform to our experimental observations, elucidate the frequency and threshold-voltage scaling in parametric VHF NEMS resonators and sensors, and establish the ultimate sensitivity limits of this approach.

  5. Parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method of ledre profile attributes

    NASA Astrophysics Data System (ADS)

    Hastuti, S.; Harijono; Murtini, E. S.; Fibrianto, K.

    2018-03-01

    This current study is aimed to investigate the use of parametric and non-parametric approach for sensory RATA (Rate-All-That-Apply) method. Ledre as Bojonegoro unique local food product was used as point of interest, in which 319 panelists were involved in the study. The result showed that ledre is characterized as easy-crushed texture, sticky in mouth, stingy sensation and easy to swallow. It has also strong banana flavour with brown in colour. Compared to eggroll and semprong, ledre has more variances in terms of taste as well the roll length. As RATA questionnaire is designed to collect categorical data, non-parametric approach is the common statistical procedure. However, similar results were also obtained as parametric approach, regardless the fact of non-normal distributed data. Thus, it suggests that parametric approach can be applicable for consumer study with large number of respondents, even though it may not satisfy the assumption of ANOVA (Analysis of Variances).

  6. Multibeam Formation with a Parametric Sonar

    DTIC Science & Technology

    1976-03-05

    AD-A022 815 MULTIBEAM FORMATION WITH A PARAMETRIC SONAR Robert L. White Texas University at Austin Prepared for: Office of Naval Research 5 March...PARAMETRIC SONAR Final Report under Contract N00014-70-A-0166, Task 0020 1 February - 31 July 1974 Robe&, L. White OFFICE OF NAVAL RESEARCH Contract N00014...78712 APPROVED FOR PUBLIC RELEASE; DISTRIBUTION UNLIMITED. r-X: ~ ... ABSTRACT Parametric sonar has proven to be an effective concept in sonar

  7. Nonlinear optics and crystalline whispering gallery mode resonators

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    We report on our recent results concerning fabrication of high-Q whispering gallery mode (WGM) crystalline resonators, and discuss some possible applications of lithium niobate WGM resonators in nonlinear optics and photonics. In particular, we demonstrate experimentally a tunable third-order optical filter fabricated from the three metalized resonators; and report observation of parametric frequency dobuling in a WGM resonator made of periodically poled lithium niobate (PPLN).

  8. Parametric infrared tunable laser system

    NASA Technical Reports Server (NTRS)

    Garbuny, M.; Henningsen, T.; Sutter, J. R.

    1980-01-01

    A parametric tunable infrared laser system was built to serve as transmitter for the remote detection and density measurement of pollutant, poisonous, or trace gases in the atmosphere. The system operates with a YAG:Nd laser oscillator amplifier chain which pumps a parametric tunable frequency converter. The completed system produced pulse energies of up to 30 mJ. The output is tunable from 1.5 to 3.6 micrometers at linewidths of 0.2-0.5 /cm (FWHM), although the limits of the tuning range and the narrower line crystals presently in the parametric converter by samples of the higher quality already demonstrated is expected to improve the system performance further.

  9. Mechanical Parametric Oscillations and Waves

    ERIC Educational Resources Information Center

    Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.

    2013-01-01

    Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…

  10. Millijoule-level 20 ps Nd:YAG oscillator-amplifier laser system for investigation of stimulated Raman scattering and optical parametric generation

    NASA Astrophysics Data System (ADS)

    Jelínek, Michal; Kubecek, Vàclav

    2012-06-01

    We report on quasi-continuously pumped oscillator-amplifier laser system. The laser oscillator was based on highly 2.4 at.% doped crystalline Nd:YAG in a bounce geometry and passively mode locked by a semiconductor saturable absorber mirror. Using the cavity dumping technique, 19 ps pulses with the energy of 20 μJ and Gaussian spatial beam profile were generated directly from the oscillator at the repetition rate up to 50 Hz. For applications requiring more energetic pulses the amplification was studied using either an identical highly doped Nd:YAG module in bounce geometry or flashlamp pumped Nd:YAG laser rod. Using compact all diode pumped oscillator-amplifier system, 130 μJ pulses were generated. The flashlamp pumped amplifier with 100 mm long Nd:YAG enabled to obtain higher energy. In the single pass configuration the pulse was amplified to 4.5 mJ, using the double pass configuration the pulse energy was further increased up to 20 mJ with the duration of 25 ps at 10 Hz. The developed laser system was used for investigation of stimulated Raman scattering in Strontium Barium Niobate and optical parametric generation in CdSiP2.

  11. Applications of high average power nonlinear optics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Velsko, S.P.; Krupke, W.F.

    1996-02-05

    Nonlinear optical frequency convertors (harmonic generators and optical parametric oscillators are reviewed with an emphasis on high average power performance and limitations. NLO materials issues and NLO device designs are discussed in reference to several emerging scientific, military and industrial commercial applications requiring {approx} 100 watt average power level in the visible and infrared spectral regions. Research efforts required to enable practical {approx} 100 watt class NLO based laser systems are identified.

  12. A fiber laser pumped dual-wavelength mid-infrared laser based on optical parametric oscillation and intracavity difference frequency generation

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Shang, Yaping; Li, Xiao; Shen, Meili; Xu, Xiaojun

    2017-02-01

    We report a dual-wavelength mid-infrared laser based on intracavity difference frequency generation (DFG) in an MgO-doped periodically poled LiNbO3, which was pumped by a dual-wavelength fiber MOPA consisting of two parts: a dual-wavelength seed and a power amplifier. The maximum pump power was 74.1 W and the wavelengths were 1060 nm and 1090 nm. The wavelengths of the mid-infrared output were 3.1 µm and 3.4 µm under maximum pump power with a total idler power of 6.57 W. The corresponding pump-to-idler slope efficiency reached 12%. The contrast for the peak intensity of the emissions for the two idlers was 0.6. A power preamplifier was added in a further experiment to enhance the contrast. The idler output reached 4.45 W under the maximum pump power of 70 W, which was lower than before. However, the contrast for the idler emission peak intensity was increased to 1.18. The signal wave generated in the experiment only had a single wavelength around 1.6 µm, indicating that two kinds of nonlinear processes occurred in the experiment, namely optical parametric oscillation and intracavity DFG.

  13. Experimental implementation of optical clockwork without carrier-envelope phase control.

    PubMed

    Mücke, O D; Kuzucu, O; Wong, F N C; Ippen, E P; Kärtner, F X; Foreman, S M; Jones, D J; Ma, L S; Hall, J L; Ye, J

    2004-12-01

    We demonstrate optical clockwork without the need for carrier-envelope phase control by use of sum-frequency generation between a continuous-wave optical parametric oscillator at 3.39 microm and a femtosecond mode-locked Ti:sapphire laser with two strong spectral peaks at 834 and 670 nm, a spectral difference matched by the 3.39-microm radiation.

  14. Pump Spectral Bandwidth, Birefringence, and Entanglement in Type-II Parametric Down Conversion

    DOE PAGES

    Erenso, Daniel

    2009-01-01

    The twin photons produced by a type-II spontaneous parametric down conversion are well know as a potential source of photons for quantum teleportation due to the strong entanglement in polarization. This strong entanglement in polarization, however, depends on the spectral composition of the pump photon and the nature of optical isotropy of the crystal. By exact numerical calculation of the concurrence, we have shown that how pump photons spectral width and the birefringence nature of the crystal directly affect the degree of polarization entanglement of the twin photons.

  15. Phase noise suppression through parametric filtering

    NASA Astrophysics Data System (ADS)

    Cassella, Cristian; Strachan, Scott; Shaw, Steven W.; Piazza, Gianluca

    2017-02-01

    In this work, we introduce and experimentally demonstrate a parametric phase noise suppression technique, which we call "parametric phase noise filtering." This technique is based on the use of a solid-state parametric amplifier operating in its instability region and included in a non-autonomous feedback loop connected at the output of a noisy oscillator. We demonstrate that such a system behaves as a parametrically driven Duffing resonator and can operate at special points where it becomes largely immune to the phase fluctuations that affect the oscillator output signal. A prototype of a parametric phase noise filter (PFIL) was designed and fabricated to operate in the very-high-frequency range. The PFIL prototype allowed us to significantly reduce the phase noise at the output of a commercial signal generator operating around 220 MHz. Noise reduction of 16 dB (40×) and 13 dB (20×) were obtained, respectively, at 1 and 10 kHz offsets from the carrier frequency. The demonstration of this phase noise suppression technique opens up scenarios in the development of passive and low-cost phase noise cancellation circuits for any application demanding high quality frequency generation.

  16. Superconducting Qubit Optical Transducer (SQOT)

    DTIC Science & Technology

    2015-08-05

    2 2.2 Qubit- Photon Entanglement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2.1 System...and a high Q will make this challenging. 3 2.2 QUBIT- PHOTON ENTANGLEMENT The parametric interaction enables interconversion between the microwave and...to observe entanglement between a qubit and optical photon and similar to experiments demonstrated solely in the microwave domain [4]: 1. Start with

  17. Applied nonlinear optics in the journal 'Quantum Electronics'

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Grechin, Sergei G; Dmitriev, Valentin G; Chirkin, Anatolii S

    2011-12-31

    A brief historical review of the experimental and theoretical works on nonlinear optical frequency conversion (generation of harmonics, up- and down-conversion, parametric oscillation), which have been published in the journal 'Quantum Electronics' for the last 40 years, is presented.

  18. Characteristics of stereo reproduction with parametric loudspeakers

    NASA Astrophysics Data System (ADS)

    Aoki, Shigeaki; Toba, Masayoshi; Tsujita, Norihisa

    2012-05-01

    A parametric loudspeaker utilizes nonlinearity of a medium and is known as a super-directivity loudspeaker. The parametric loudspeaker is one of the prominent applications of nonlinear ultrasonics. So far, the applications have been limited monaural reproduction sound system for public address in museum, station and street etc. In this paper, we discussed characteristics of stereo reproduction with two parametric loudspeakers by comparing with those with two ordinary dynamic loudspeakers. In subjective tests, three typical listening positions were selected to investigate the possibility of correct sound localization in a wide listening area. The binaural information was ILD (Interaural Level Difference) or ITD (Interaural Time Delay). The parametric loudspeaker was an equilateral hexagon. The inner and outer diameters were 99 and 112 mm, respectively. Signals were 500 Hz, 1 kHz, 2 kHz and 4 kHz pure tones and pink noise. Three young males listened to test signals 10 times in each listening condition. Subjective test results showed that listeners at the three typical listening positions perceived correct sound localization of all signals using the parametric loudspeakers. It was almost similar to those using the ordinary dynamic loudspeakers, however, except for the case of sinusoidal waves with ITD. It was determined the parametric loudspeaker could exclude the contradiction between the binaural information ILD and ITD that occurred in stereo reproduction with ordinary dynamic loudspeakers because the super directivity of parametric loudspeaker suppressed the cross talk components.

  19. Energy dependence of nonlocal optical potentials

    NASA Astrophysics Data System (ADS)

    Lovell, A. E.; Bacq, P.-L.; Capel, P.; Nunes, F. M.; Titus, L. J.

    2017-11-01

    Recently, a variety of studies have shown the importance of including nonlocality in the description of reactions. The goal of this work is to revisit the phenomenological approach to determining nonlocal optical potentials from elastic scattering. We perform a χ2 analysis of neutron elastic scattering data off 40Ca, 90Zr, and 208Pb at energies E ≈5 -40 MeV, assuming a Perey and Buck [Nucl. Phys. 32, 353 (1962), 10.1016/0029-5582(62)90345-0] or Tian et al. [Int. J. Mod. Phys. E 24, 1550006 (2015), 10.1142/S0218301315500068] nonlocal form for the optical potential. We introduce energy and asymmetry dependencies in the imaginary part of the potential and refit the data to obtain a global parametrization. Independently of the starting point in the minimization procedure, an energy dependence in the imaginary depth is required for a good description of the data across the included energy range. We present two parametrizations, both of which represent an improvement over the original potentials for the fitted nuclei as well as for other nuclei not included in our fit. Our results show that, even when including the standard Gaussian nonlocality in optical potentials, a significant energy dependence is required to describe elastic-scattering data.

  20. An improvement of quantum parametric methods by using SGSA parameterization technique and new elementary parametric functionals

    NASA Astrophysics Data System (ADS)

    Sánchez, M.; Oldenhof, M.; Freitez, J. A.; Mundim, K. C.; Ruette, F.

    A systematic improvement of parametric quantum methods (PQM) is performed by considering: (a) a new application of parameterization procedure to PQMs and (b) novel parametric functionals based on properties of elementary parametric functionals (EPF) [Ruette et al., Int J Quantum Chem 2008, 108, 1831]. Parameterization was carried out by using the simplified generalized simulated annealing (SGSA) method in the CATIVIC program. This code has been parallelized and comparison with MOPAC/2007 (PM6) and MINDO/SR was performed for a set of molecules with C=C, C=H, and H=H bonds. Results showed better accuracy than MINDO/SR and MOPAC-2007 for a selected trial set of molecules.

  1. Grating lobe elimination in steerable parametric loudspeaker.

    PubMed

    Shi, Chuang; Gan, Woon-Seng

    2011-02-01

    In the past two decades, the majority of research on the parametric loudspeaker has concentrated on the nonlinear modeling of acoustic propagation and pre-processing techniques to reduce nonlinear distortion in sound reproduction. There are, however, very few studies on directivity control of the parametric loudspeaker. In this paper, we propose an equivalent circular Gaussian source array that approximates the directivity characteristics of the linear ultrasonic transducer array. By using this approximation, the directivity of the sound beam from the parametric loudspeaker can be predicted by the product directivity principle. New theoretical results, which are verified through measurements, are presented to show the effectiveness of the delay-and-sum beamsteering structure for the parametric loudspeaker. Unlike the conventional loudspeaker array, where the spacing between array elements must be less than half the wavelength to avoid spatial aliasing, the parametric loudspeaker can take advantage of grating lobe elimination to extend the spacing of ultrasonic transducer array to more than 1.5 wavelengths in a typical application.

  2. Estimating technical efficiency in the hospital sector with panel data: a comparison of parametric and non-parametric techniques.

    PubMed

    Siciliani, Luigi

    2006-01-01

    Policy makers are increasingly interested in developing performance indicators that measure hospital efficiency. These indicators may give the purchasers of health services an additional regulatory tool to contain health expenditure. Using panel data, this study compares different parametric (econometric) and non-parametric (linear programming) techniques for the measurement of a hospital's technical efficiency. This comparison was made using a sample of 17 Italian hospitals in the years 1996-9. Highest correlations are found in the efficiency scores between the non-parametric data envelopment analysis under the constant returns to scale assumption (DEA-CRS) and several parametric models. Correlation reduces markedly when using more flexible non-parametric specifications such as data envelopment analysis under the variable returns to scale assumption (DEA-VRS) and the free disposal hull (FDH) model. Correlation also generally reduces when moving from one output to two-output specifications. This analysis suggests that there is scope for developing performance indicators at hospital level using panel data, but it is important that extensive sensitivity analysis is carried out if purchasers wish to make use of these indicators in practice.

  3. Simultaneous measurement and modulation of multiple physiological parameters in the isolated heart using optical techniques

    PubMed Central

    Lee, Peter; Yan, Ping; Ewart, Paul; Kohl, Peter

    2012-01-01

    Whole-heart multi-parametric optical mapping has provided valuable insight into the interplay of electro-physiological parameters, and this technology will continue to thrive as dyes are improved and technical solutions for imaging become simpler and cheaper. Here, we show the advantage of using improved 2nd-generation voltage dyes, provide a simple solution to panoramic multi-parametric mapping, and illustrate the application of flash photolysis of caged compounds for studies in the whole heart. For proof of principle, we used the isolated rat whole-heart model. After characterising the blue and green isosbestic points of di-4-ANBDQBS and di-4-ANBDQPQ, respectively, two voltage and calcium mapping systems are described. With two newly custom-made multi-band optical filters, (1) di-4-ANBDQBS and fluo-4 and (2) di-4-ANBDQPQ and rhod-2 mapping are demonstrated. Furthermore, we demonstrate three-parameter mapping using di-4-ANBDQPQ, rhod-2 and NADH. Using off-the-shelf optics and the di-4-ANBDQPQ and rhod-2 combination, we demonstrate panoramic multi-parametric mapping, affording a 360° spatiotemporal record of activity. Finally, local optical perturbation of calcium dynamics in the whole heart is demonstrated using the caged compound, o-nitrophenyl ethylene glycol tetraacetic acid (NP-EGTA), with an ultraviolet light-emitting diode (LED). Calcium maps (heart loaded with di-4-ANBDQPQ and rhod-2) demonstrate successful NP-EGTA loading and local flash photolysis. All imaging systems were built using only a single camera. In conclusion, using novel 2nd-generation voltage dyes, we developed scalable techniques for multi-parametric optical mapping of the whole heart from one point of view and panoramically. In addition to these parameter imaging approaches, we show that it is possible to use caged compounds and ultraviolet LEDs to locally perturb electrophysiological parameters in the whole heart. PMID:22886365

  4. Double-pump-pass singly resonant optical parametric oscillator for efficient generation of infrared light at 2300 nm based on PPMgSLT

    NASA Astrophysics Data System (ADS)

    Lee, Seungmin; Rhee, Bum Ku

    2015-02-01

    The pump laser was a cw-diode-pumped, acousto-optically Q-switched Nd:YAG laser. The laser had a pulse width of ~85 ns when operating at 10 kHz repetition rates. For infrared output of 2300 nm, we used 35-mm-long PPMgSLT which has a grating period of 32.7 μm for the first-order quasi-phase matching, resulting in the signal wavelength of 1980 nm at the crystal temperature of 76.5oC. Our optical parametric oscillator (OPO) was of a simple linear extra-cavity structure, formed by two flat dichroic mirrors with a separation of ~45 mm. The input coupling mirror had a high transmission of 98% for the pump, high reflectance of 98% at the signal and idler wavelengths, whereas the output coupler had a high reflectance of 98% at the pump wavelength. Hence, the OPO can be considered as singly resonant with double-pass pumping. In order to find an optimum reflectance for the efficient generation of infrared radiation of 2300 nm, we used the three different output mirrors whose reflectivity are ranging from 90% to 38% at the signal wavelength. We measured the signal and idler power as a function of the pumping power of Nd:YAG laser for three different output couplers. A maximum extraction efficiency with an optimum reflectance of output mirror was 27% for the idler, corresponding to 5.6 W of average output power. The fluctuations in the idler root-mean-square output power were measured to be below 1.5%. Our result is comparable with the recent one based on PPLN even with a simple cavity.

  5. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1996-12-17

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source, a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference line as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  6. Nonimaging optical illumination system

    DOEpatents

    Winston, R.; Ries, H.

    1998-10-06

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source a light reflecting surface, and a family of light edge rays defined along a reference line with the reflecting surface defined in terms of the reference lines a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line, and D is a distance from a point on the reference line to the reflection surface along the desired edge ray through the point. 35 figs.

  7. Compact, flexible, frequency agile parametric wavelength converter

    DOEpatents

    Velsko, Stephan P.; Yang, Steven T.

    2002-01-01

    This improved Frequency Agile Optical Parametric Oscillator provides near on-axis pumping of a single QPMC with a tilted periodically poled grating to overcome the necessity to find a particular crystal that will permit collinear birefringence in order to obtain a desired tuning range. A tilted grating design and the elongation of the transverse profile of the pump beam in the angle tuning plane of the FA-OPO reduces the rate of change of the overlap between the pumped volume in the crystal and the resonated and non-resonated wave mode volumes as the pump beam angle is changed. A folded mirror set relays the pivot point for beam steering from a beam deflector to the center of the FA-OPO crystal. This reduces the footprint of the device by as much as a factor of two over that obtained when using the refractive telescope design.

  8. Micro-Structured Materials for Generation of Coherent Light and Optical Signal Processing

    DTIC Science & Technology

    2008-12-22

    Bliss, and D. Weyburne,, "GaAs optical parametric oscillator with circularly polarized and depolarized pump", Optics Letters, No. 18, Vol. 32, pp...Because we measure the space-charge field by propagating the intense green laser beam along the crystal c- axis, the polarization of the light is...ordinary. Most applications utilize light with extraordinary polarization to make use of the largest component of the nonlinear or electro-optic tensor

  9. Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods: A Comparison with Clinical Assessment

    PubMed Central

    Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H.; Maurits, Natasha M.

    2016-01-01

    In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a better insight into tremor. Typically, routine clinical assessment of accelerometry and electromyography data involves visual inspection by clinicians and occasionally computational analysis to obtain objective characteristics of tremor. However, for some tremor disorders these characteristics may be different during daily activity. This variability in presentation between the clinic and daily life makes a differential diagnosis more difficult. A long-term recording of tremor by accelerometry and/or electromyography in the home environment could help to give a better insight into the tremor disorder. However, an evaluation of such recordings using routine clinical standards would take too much time. We evaluated a range of techniques that automatically detect tremor segments in accelerometer data, as accelerometer data is more easily obtained in the home environment than electromyography data. Time can be saved if clinicians only have to evaluate the tremor characteristics of segments that have been automatically detected in longer daily activity recordings. We tested four non-parametric methods and five parametric methods on clinical accelerometer data from 14 patients with different tremor disorders. The consensus between two clinicians regarding the presence or absence of tremor on 3943 segments of accelerometer data was employed as reference. The nine methods were tested against this reference to identify their optimal parameters. Non-parametric methods generally performed better than parametric methods on our dataset when optimal parameters were used. However, one parametric method, employing the high frequency content of the tremor bandwidth under consideration

  10. Parametric robust control and system identification: Unified approach

    NASA Technical Reports Server (NTRS)

    Keel, Leehyun

    1994-01-01

    Despite significant advancement in the area of robust parametric control, the problem of synthesizing such a controller is still a wide open problem. Thus, we attempt to give a solution to this important problem. Our approach captures the parametric uncertainty as an H(sub infinity) unstructured uncertainty so that H(sub infinity) synthesis techniques are applicable. Although the techniques cannot cope with the exact parametric uncertainty, they give a reasonable guideline to model the unstructured uncertainty that contains the parametric uncertainty. An additional loop shaping technique is also introduced to relax its conservatism.

  11. Zero- vs. one-dimensional, parametric vs. non-parametric, and confidence interval vs. hypothesis testing procedures in one-dimensional biomechanical trajectory analysis.

    PubMed

    Pataky, Todd C; Vanrenterghem, Jos; Robinson, Mark A

    2015-05-01

    Biomechanical processes are often manifested as one-dimensional (1D) trajectories. It has been shown that 1D confidence intervals (CIs) are biased when based on 0D statistical procedures, and the non-parametric 1D bootstrap CI has emerged in the Biomechanics literature as a viable solution. The primary purpose of this paper was to clarify that, for 1D biomechanics datasets, the distinction between 0D and 1D methods is much more important than the distinction between parametric and non-parametric procedures. A secondary purpose was to demonstrate that a parametric equivalent to the 1D bootstrap exists in the form of a random field theory (RFT) correction for multiple comparisons. To emphasize these points we analyzed six datasets consisting of force and kinematic trajectories in one-sample, paired, two-sample and regression designs. Results showed, first, that the 1D bootstrap and other 1D non-parametric CIs were qualitatively identical to RFT CIs, and all were very different from 0D CIs. Second, 1D parametric and 1D non-parametric hypothesis testing results were qualitatively identical for all six datasets. Last, we highlight the limitations of 1D CIs by demonstrating that they are complex, design-dependent, and thus non-generalizable. These results suggest that (i) analyses of 1D data based on 0D models of randomness are generally biased unless one explicitly identifies 0D variables before the experiment, and (ii) parametric and non-parametric 1D hypothesis testing provide an unambiguous framework for analysis when one׳s hypothesis explicitly or implicitly pertains to whole 1D trajectories. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Quasi-monolithic tunable optical resonator

    NASA Technical Reports Server (NTRS)

    Arbore, Mark (Inventor); Tapos, Francisc (Inventor)

    2003-01-01

    An optical resonator has a piezoelectric element attached to a quasi-monolithic structure. The quasi-monolithic structure defines an optical path. Mirrors attached to the structure deflect light along the optical path. The piezoelectric element controllably strains the quasi-monolithic structure to change a length of the optical path by about 1 micron. A first feedback loop coupled to the piezoelectric element provides fine control over the cavity length. The resonator may include a thermally actuated spacer attached to the cavity and a mirror attached to the spacer. The thermally actuated spacer adjusts the cavity length by up to about 20 microns. A second feedback loop coupled to the sensor and heater provides a coarse control over the cavity length. An alternative embodiment provides a quasi-monolithic optical parametric oscillator (OPO). This embodiment includes a non-linear optical element within the resonator cavity along the optical path. Such an OPO configuration is broadly tunable and capable of mode-hop free operation for periods of 24 hours or more.

  13. Registration of parametric dynamic F-18-FDG PET/CT breast images with parametric dynamic Gd-DTPA breast images

    NASA Astrophysics Data System (ADS)

    Magri, Alphonso; Krol, Andrzej; Lipson, Edward; Mandel, James; McGraw, Wendy; Lee, Wei; Tillapaugh-Fay, Gwen; Feiglin, David

    2009-02-01

    This study was undertaken to register 3D parametric breast images derived from Gd-DTPA MR and F-18-FDG PET/CT dynamic image series. Nonlinear curve fitting (Levenburg-Marquardt algorithm) based on realistic two-compartment models was performed voxel-by-voxel separately for MR (Brix) and PET (Patlak). PET dynamic series consists of 50 frames of 1-minute duration. Each consecutive PET image was nonrigidly registered to the first frame using a finite element method and fiducial skin markers. The 12 post-contrast MR images were nonrigidly registered to the precontrast frame using a free-form deformation (FFD) method. Parametric MR images were registered to parametric PET images via CT using FFD because the first PET time frame was acquired immediately after the CT image on a PET/CT scanner and is considered registered to the CT image. We conclude that nonrigid registration of PET and MR parametric images using CT data acquired during PET/CT scan and the FFD method resulted in their improved spatial coregistration. The success of this procedure was limited due to relatively large target registration error, TRE = 15.1+/-7.7 mm, as compared to spatial resolution of PET (6-7 mm), and swirling image artifacts created in MR parametric images by the FFD. Further refinement of nonrigid registration of PET and MR parametric images is necessary to enhance visualization and integration of complex diagnostic information provided by both modalities that will lead to improved diagnostic performance.

  14. Parametric and non-parametric species delimitation methods result in the recognition of two new Neotropical woody bamboo species.

    PubMed

    Ruiz-Sanchez, Eduardo

    2015-12-01

    The Neotropical woody bamboo genus Otatea is one of five genera in the subtribe Guaduinae. Of the eight described Otatea species, seven are endemic to Mexico and one is also distributed in Central and South America. Otatea acuminata has the widest geographical distribution of the eight species, and two of its recently collected populations do not match the known species morphologically. Parametric and non-parametric methods were used to delimit the species in Otatea using five chloroplast markers, one nuclear marker, and morphological characters. The parametric coalescent method and the non-parametric analysis supported the recognition of two distinct evolutionary lineages. Molecular clock estimates were used to estimate divergence times in Otatea. The results for divergence time in Otatea estimated the origin of the speciation events from the Late Miocene to Late Pleistocene. The species delimitation analyses (parametric and non-parametric) identified that the two populations of O. acuminata from Chiapas and Hidalgo are from two separate evolutionary lineages and these new species have morphological characters that separate them from O. acuminata s.s. The geological activity of the Trans-Mexican Volcanic Belt and the Isthmus of Tehuantepec may have isolated populations and limited the gene flow between Otatea species, driving speciation. Based on the results found here, I describe Otatea rzedowskiorum and Otatea victoriae as two new species, morphologically different from O. acuminata. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. A review of parametric approaches specific to aerodynamic design process

    NASA Astrophysics Data System (ADS)

    Zhang, Tian-tian; Wang, Zhen-guo; Huang, Wei; Yan, Li

    2018-04-01

    Parametric modeling of aircrafts plays a crucial role in the aerodynamic design process. Effective parametric approaches have large design space with a few variables. Parametric methods that commonly used nowadays are summarized in this paper, and their principles have been introduced briefly. Two-dimensional parametric methods include B-Spline method, Class/Shape function transformation method, Parametric Section method, Hicks-Henne method and Singular Value Decomposition method, and all of them have wide application in the design of the airfoil. This survey made a comparison among them to find out their abilities in the design of the airfoil, and the results show that the Singular Value Decomposition method has the best parametric accuracy. The development of three-dimensional parametric methods is limited, and the most popular one is the Free-form deformation method. Those methods extended from two-dimensional parametric methods have promising prospect in aircraft modeling. Since different parametric methods differ in their characteristics, real design process needs flexible choice among them to adapt to subsequent optimization procedure.

  16. Second harmonic generation in resonant optical structures

    DOEpatents

    Eichenfield, Matt; Moore, Jeremy; Friedmann, Thomas A.; Olsson, Roy H.; Wiwi, Michael; Padilla, Camille; Douglas, James Kenneth; Hattar, Khalid Mikhiel

    2018-01-09

    An optical second-harmonic generator (or spontaneous parametric down-converter) includes a microresonator formed of a nonlinear optical medium. The microresonator supports at least two modes that can be phase matched at different frequencies so that light can be converted between them: A first resonant mode having substantially radial polarization and a second resonant mode having substantially vertical polarization. The first and second modes have the same radial order. The thickness of the nonlinear medium is less than one-half the pump wavelength within the medium.

  17. Characterization of Ultrafast Laser Pulses using a Low-dispersion Frequency Resolved Optical Grating Spectrometer

    NASA Astrophysics Data System (ADS)

    Whitelock, Hope; Bishop, Michael; Khosravi, Soroush; Obaid, Razib; Berrah, Nora

    2016-05-01

    A low dispersion frequency-resolved optical gating (FROG) spectrometer was designed to characterize ultrashort (<50 femtosecond) laser pulses from a commercial regenerative amplifier, optical parametric amplifier, and a home-built non-colinear optical parametric amplifier. This instrument splits a laser pulse into two replicas with a 90:10 intensity ratio using a thin pellicle beam-splitter and then recombines the pulses in a birefringent medium. The instrument detects a wavelength-sensitive change in polarization of the weak probe pulse in the presence of the stronger pump pulse inside the birefringent medium. Scanning the time delay between the two pulses and acquiring spectra allows for characterization of the frequency and time content of ultrafast laser pulses, that is needed for interpretation of experimental results obtained from these ultrafast laser systems. Funded by the DoE-BES, Grant No. DE-SC0012376.

  18. Parametric Cost Models for Space Telescopes

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip

    2010-01-01

    A study is in-process to develop a multivariable parametric cost model for space telescopes. Cost and engineering parametric data has been collected on 30 different space telescopes. Statistical correlations have been developed between 19 variables of 59 variables sampled. Single Variable and Multi-Variable Cost Estimating Relationships have been developed. Results are being published.

  19. 5-fs, Multi-mJ, CEP-locked parametric chirped-pulse amplifier pumped by a 450-nm source at 1 kHz.

    PubMed

    Adachi, S; Ishii, N; Kanai, T; Kosuge, A; Itatani, J; Kobayashi, Y; Yoshitomi, D; Torizuka, K; Watanabe, S

    2008-09-15

    We report on the development of an optical parametric chirpedpulse amplifier at a 1-kHz repetition rate with a 5.5-fs pulse duration, a 2.7-mJ pulse energy and carrier-envelope phase-control. The amplifier is pumped by a 450-nm pulse from a frequency-doubled Ti:sapphire laser.

  20. Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    J.A. Maloney, K.B. Beard, R.P. Johnson, A. Afanasev, S.A. Bogacz, Y.S. Derbenev, V.S. Morozov, B. Erdelyi

    2012-07-01

    A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessarymore » to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.« less

  1. Frequency-domain nonlinear optics in two-dimensionally patterned quasi-phase-matching media.

    PubMed

    Phillips, C R; Mayer, B W; Gallmann, L; Keller, U

    2016-07-11

    Advances in the amplification and manipulation of ultrashort laser pulses have led to revolutions in several areas. Examples include chirped pulse amplification for generating high peak-power lasers, power-scalable amplification techniques, pulse shaping via modulation of spatially-dispersed laser pulses, and efficient frequency-mixing in quasi-phase-matched nonlinear crystals to access new spectral regions. In this work, we introduce and demonstrate a new platform for nonlinear optics which has the potential to combine these separate functionalities (pulse amplification, frequency transfer, and pulse shaping) into a single monolithic device that is bandwidth- and power-scalable. The approach is based on two-dimensional (2D) patterning of quasi-phase-matching (QPM) gratings combined with optical parametric interactions involving spatially dispersed laser pulses. Our proof of principle experiment demonstrates this technique via mid-infrared optical parametric chirped pulse amplification of few-cycle pulses. Additionally, we present a detailed theoretical and numerical analysis of such 2D-QPM devices and how they can be designed.

  2. Parametric and Non-Parametric Vibration-Based Structural Identification Under Earthquake Excitation

    NASA Astrophysics Data System (ADS)

    Pentaris, Fragkiskos P.; Fouskitakis, George N.

    2014-05-01

    The problem of modal identification in civil structures is of crucial importance, and thus has been receiving increasing attention in recent years. Vibration-based methods are quite promising as they are capable of identifying the structure's global characteristics, they are relatively easy to implement and they tend to be time effective and less expensive than most alternatives [1]. This paper focuses on the off-line structural/modal identification of civil (concrete) structures subjected to low-level earthquake excitations, under which, they remain within their linear operating regime. Earthquakes and their details are recorded and provided by the seismological network of Crete [2], which 'monitors' the broad region of south Hellenic arc, an active seismic region which functions as a natural laboratory for earthquake engineering of this kind. A sufficient number of seismic events are analyzed in order to reveal the modal characteristics of the structures under study, that consist of the two concrete buildings of the School of Applied Sciences, Technological Education Institute of Crete, located in Chania, Crete, Hellas. Both buildings are equipped with high-sensitivity and accuracy seismographs - providing acceleration measurements - established at the basement (structure's foundation) presently considered as the ground's acceleration (excitation) and at all levels (ground floor, 1st floor, 2nd floor and terrace). Further details regarding the instrumentation setup and data acquisition may be found in [3]. The present study invokes stochastic, both non-parametric (frequency-based) and parametric methods for structural/modal identification (natural frequencies and/or damping ratios). Non-parametric methods include Welch-based spectrum and Frequency response Function (FrF) estimation, while parametric methods, include AutoRegressive (AR), AutoRegressive with eXogeneous input (ARX) and Autoregressive Moving-Average with eXogeneous input (ARMAX) models[4, 5

  3. Detection of two-mode compression and degree of entanglement in continuous variables in parametric scattering of light

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rytikov, G. O.; Chekhova, M. V.

    2008-12-15

    Generation of 'twin beams' (of light with two-mode compression) in single-pass optical parametric amplifier (a crystal with a nonzero quadratic susceptibility) is considered. Radiation at the output of the nonlinear crystal is essentially multimode, which raises the question about the effect of the detection volume on the extent of suppression of noise from the difference photocurrent of the detectors. In addition, the longitudinal as well as transverse size of the region in which parametric transformation takes place is of fundamental importance. It is shown that maximal suppression of noise from difference photocurrent requires a high degree of entanglement of two-photonmore » light at the outlet of the parametric amplifier, which is defined by Federov et al. [Phys. Rev. A 77, 032336 (2008)] as the ratio of the intensity distribution width to the correlation function width. The detection volume should be chosen taking into account both these quantities. Various modes of single-pass generation of twin beams (noncollinear frequency-degenerate and collinear frequency-nondegenerate synchronism of type I, as well as collinear frequency-degenerate synchronism of type II) are considered in connection with the degree of entanglement.« less

  4. Parametrically disciplined operation of a vibratory gyroscope

    NASA Technical Reports Server (NTRS)

    Shcheglov, Kirill V. (Inventor); Challoner, A. Dorian (Inventor); Hayworth, Ken J. (Inventor); Peay, Chris S. (Inventor)

    2008-01-01

    Parametrically disciplined operation of a symmetric nearly degenerate mode vibratory gyroscope is disclosed. A parametrically-disciplined inertial wave gyroscope having a natural oscillation frequency in the neighborhood of a sub-harmonic of an external stable clock reference is produced by driving an electrostatic bias electrode at approximately twice this sub-harmonic frequency to achieve disciplined frequency and phase operation of the resonator. A nearly symmetric parametrically-disciplined inertial wave gyroscope that can oscillate in any transverse direction and has more than one bias electrostatic electrode that can be independently driven at twice its oscillation frequency at an amplitude and phase that disciplines its damping to zero in any vibration direction. In addition, operation of a parametrically-disciplined inertial wave gyroscope is taught in which the precession rate of the driven vibration pattern is digitally disciplined to a prescribed non-zero reference value.

  5. Interplanetary approach optical navigation with applications

    NASA Technical Reports Server (NTRS)

    Jerath, N.

    1978-01-01

    The use of optical data from onboard television cameras for the navigation of interplanetary spacecraft during the planet approach phase is investigated. Three optical data types were studied: the planet limb with auxiliary celestial references, the satellite-star, and the planet-star two-camera methods. Analysis and modelling issues related to the nature and information content of the optical methods were examined. Dynamic and measurement system modelling, data sequence design, measurement extraction, model estimation and orbit determination, as relating optical navigation, are discussed, and the various error sources were analyzed. The methodology developed was applied to the Mariner 9 and the Viking Mars missions. Navigation accuracies were evaluated at the control and knowledge points, with particular emphasis devoted to the combined use of radio and optical data. A parametric probability analysis technique was developed to evaluate navigation performance as a function of system reliabilities.

  6. Theoretical analysis of terahertz generation from a compact optical parametric oscillator based on adhesive-free-bonded periodically inverted KTiOPO4 plates

    NASA Astrophysics Data System (ADS)

    Li, Zhongyang; Wang, Silei; Wang, Mengtao; Yuan, Bin; Wang, Weishu

    2017-10-01

    Terahertz (THz) generation by difference frequency generation (DFG) processes with dual signal waves is theoretically analyzed. The dual signal waves are generated by an optical parametric oscillator (OPO) with periodically inverted KTiOPO4 (KTP) plates based on adhesive-free-bonded (AFB) technology. The phase-matching conditions in a same AFB KTP composite for the OPO generating signals and idlers and for the DFG generating THz wave can be simultaneously satisfied by selecting the thickness of each KTP plate. Moreover, 4-order cascaded DFG processes can be realized in the same AFB KTP composite. The cascaded Stokes interaction processes generating THz photons and the cascaded anti-Stokes interaction processes consuming THz photons are investigated from coupled wave equations. Take an example of 3.106 THz which locates in the vicinity of polariton resonances, THz intensities and quantum conversion efficiencies are calculated. Compared with non-cascaded DFG processes, THz intensities of 3.106 THz in 4-order cascaded DFG processes increase to 5.56 times. When the pump intensity equals 20 MW mm-2, the quantum conversion efficiency of 259% in 4-order cascaded DFG processes can be realized, which exceeds the Manley-Rowe limit.

  7. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    2000-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  8. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1998-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  9. Nonimaging optical illumination system

    DOEpatents

    Winston, Roland; Ries, Harald

    1996-01-01

    A nonimaging illumination optical device for producing a selected far field illuminance over an angular range. The optical device includes a light source 102, a light reflecting surface 108, and a family of light edge rays defined along a reference line 104 with the reflecting surface 108 defined in terms of the reference line 104 as a parametric function R(t) where t is a scalar parameter position and R(t)=k(t)+Du(t) where k(t) is a parameterization of the reference line 104, and D is a distance from a point on the reference line 104 to the reflection surface 108 along the desired edge ray through the point.

  10. Parametric FEM for geometric biomembranes

    NASA Astrophysics Data System (ADS)

    Bonito, Andrea; Nochetto, Ricardo H.; Sebastian Pauletti, M.

    2010-05-01

    We consider geometric biomembranes governed by an L2-gradient flow for bending energy subject to area and volume constraints (Helfrich model). We give a concise derivation of a novel vector formulation, based on shape differential calculus, and corresponding discretization via parametric FEM using quadratic isoparametric elements and a semi-implicit Euler method. We document the performance of the new parametric FEM with a number of simulations leading to dumbbell, red blood cell and toroidal equilibrium shapes while exhibiting large deformations.

  11. Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation

    PubMed Central

    Shahid, Wajiha; Qiu, Zhen; Duan, Xiyu; Li, Haijun; Wang, Thomas D.; Oldham, Kenn R.

    2014-01-01

    High frequency large scanning angle electrostatically actuated microelectromechanical systems (MEMS) mirrors are used in a variety of applications involving fast optical scanning. A 1-D parametrically resonant torsional micromirror for use in biomedical imaging is analyzed here with respect to operation by duty-cycled square waves. Duty-cycled square wave excitation can have significant advantages for practical mirror regulation and/or control. The mirror’s nonlinear dynamics under such excitation is analyzed in a Hill’s equation form. This form is used to predict stability regions (the voltage-frequency relationship) of parametric resonance behavior over large scanning angles using iterative approximations for nonlinear capacitance behavior of the mirror. Numerical simulations are also performed to obtain the mirror’s frequency response over several voltages for various duty cycles. Frequency sweeps, stability results, and duty cycle trends from both analytical and simulation methods are compared with experimental results. Both analytical models and simulations show good agreement with experimental results over the range of duty cycled excitations tested. This paper discusses the implications of changing amplitude and phase with duty cycle for robust open-loop operation and future closed-loop operating strategies. PMID:25506188

  12. Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation.

    PubMed

    Shahid, Wajiha; Qiu, Zhen; Duan, Xiyu; Li, Haijun; Wang, Thomas D; Oldham, Kenn R

    2014-12-01

    High frequency large scanning angle electrostatically actuated microelectromechanical systems (MEMS) mirrors are used in a variety of applications involving fast optical scanning. A 1-D parametrically resonant torsional micromirror for use in biomedical imaging is analyzed here with respect to operation by duty-cycled square waves. Duty-cycled square wave excitation can have significant advantages for practical mirror regulation and/or control. The mirror's nonlinear dynamics under such excitation is analyzed in a Hill's equation form. This form is used to predict stability regions (the voltage-frequency relationship) of parametric resonance behavior over large scanning angles using iterative approximations for nonlinear capacitance behavior of the mirror. Numerical simulations are also performed to obtain the mirror's frequency response over several voltages for various duty cycles. Frequency sweeps, stability results, and duty cycle trends from both analytical and simulation methods are compared with experimental results. Both analytical models and simulations show good agreement with experimental results over the range of duty cycled excitations tested. This paper discusses the implications of changing amplitude and phase with duty cycle for robust open-loop operation and future closed-loop operating strategies.

  13. Ku band low noise parametric amplifier

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A low noise, K sub u-band, parametric amplifier (paramp) was developed. The unit is a spacecraft-qualifiable, prototype, parametric amplifier for eventual application in the shuttle orbiter. The amplifier was required to have a noise temperature of less than 150 K. A noise temperature of less than 120 K at a gain level of 17 db was achieved. A 3-db bandwidth in excess of 350 MHz was attained, while deviation from phase linearity of about + or - 1 degree over 50 MHz was achieved. The paramp operates within specification over an ambient temperature range of -5 C to +50 C. The performance requirements and the operation of the K sub u-band parametric amplifier system are described. The final test results are also given.

  14. Parametric analysis of ATM solar array.

    NASA Technical Reports Server (NTRS)

    Singh, B. K.; Adkisson, W. B.

    1973-01-01

    The paper discusses the methods used for the calculation of ATM solar array performance characteristics and provides the parametric analysis of solar panels used in SKYLAB. To predict the solar array performance under conditions other than test conditions, a mathematical model has been developed. Four computer programs have been used to convert the solar simulator test data to the parametric curves. The first performs module summations, the second determines average solar cell characteristics which will cause a mathematical model to generate a curve matching the test data, the third is a polynomial fit program which determines the polynomial equations for the solar cell characteristics versus temperature, and the fourth program uses the polynomial coefficients generated by the polynomial curve fit program to generate the parametric data.

  15. Housing price prediction: parametric versus semi-parametric spatial hedonic models

    NASA Astrophysics Data System (ADS)

    Montero, José-María; Mínguez, Román; Fernández-Avilés, Gema

    2018-01-01

    House price prediction is a hot topic in the economic literature. House price prediction has traditionally been approached using a-spatial linear (or intrinsically linear) hedonic models. It has been shown, however, that spatial effects are inherent in house pricing. This article considers parametric and semi-parametric spatial hedonic model variants that account for spatial autocorrelation, spatial heterogeneity and (smooth and nonparametrically specified) nonlinearities using penalized splines methodology. The models are represented as a mixed model that allow for the estimation of the smoothing parameters along with the other parameters of the model. To assess the out-of-sample performance of the models, the paper uses a database containing the price and characteristics of 10,512 homes in Madrid, Spain (Q1 2010). The results obtained suggest that the nonlinear models accounting for spatial heterogeneity and flexible nonlinear relationships between some of the individual or areal characteristics of the houses and their prices are the best strategies for house price prediction.

  16. Pilot-based parametric channel estimation algorithm for DCO-OFDM-based visual light communications

    NASA Astrophysics Data System (ADS)

    Qian, Xuewen; Deng, Honggui; He, Hailang

    2017-10-01

    Due to wide modulation bandwidth in optical communication, multipath channels may be non-sparse and deteriorate communication performance heavily. Traditional compressive sensing-based channel estimation algorithm cannot be employed in this kind of situation. In this paper, we propose a practical parametric channel estimation algorithm for orthogonal frequency division multiplexing (OFDM)-based visual light communication (VLC) systems based on modified zero correlation code (ZCC) pair that has the impulse-like correlation property. Simulation results show that the proposed algorithm achieves better performances than existing least squares (LS)-based algorithm in both bit error ratio (BER) and frequency response estimation.

  17. Comparison of thawing and freezing dark energy parametrizations

    NASA Astrophysics Data System (ADS)

    Pantazis, G.; Nesseris, S.; Perivolaropoulos, L.

    2016-05-01

    Dark energy equation of state w (z ) parametrizations with two parameters and given monotonicity are generically either convex or concave functions. This makes them suitable for fitting either freezing or thawing quintessence models but not both simultaneously. Fitting a data set based on a freezing model with an unsuitable (concave when increasing) w (z ) parametrization [like Chevallier-Polarski-Linder (CPL)] can lead to significant misleading features like crossing of the phantom divide line, incorrect w (z =0 ), incorrect slope, etc., that are not present in the underlying cosmological model. To demonstrate this fact we generate scattered cosmological data at both the level of w (z ) and the luminosity distance DL(z ) based on either thawing or freezing quintessence models and fit them using parametrizations of convex and of concave type. We then compare statistically significant features of the best fit w (z ) with actual features of the underlying model. We thus verify that the use of unsuitable parametrizations can lead to misleading conclusions. In order to avoid these problems it is important to either use both convex and concave parametrizations and select the one with the best χ2 or use principal component analysis thus splitting the redshift range into independent bins. In the latter case, however, significant information about the slope of w (z ) at high redshifts is lost. Finally, we propose a new family of parametrizations w (z )=w0+wa(z/1 +z )n which generalizes the CPL and interpolates between thawing and freezing parametrizations as the parameter n increases to values larger than 1.

  18. Parametric pendulum based wave energy converter

    NASA Astrophysics Data System (ADS)

    Yurchenko, Daniil; Alevras, Panagiotis

    2018-01-01

    The paper investigates the dynamics of a novel wave energy converter based on the parametrically excited pendulum. The herein developed concept of the parametric pendulum allows reducing the influence of the gravity force thereby significantly improving the device performance at a regular sea state, which could not be achieved in the earlier proposed original point-absorber design. The suggested design of a wave energy converter achieves a dominant rotational motion without any additional mechanisms, like a gearbox, or any active control involvement. Presented numerical results of deterministic and stochastic modeling clearly reflect the advantage of the proposed design. A set of experimental results confirms the numerical findings and validates the new design of a parametric pendulum based wave energy converter. Power harvesting potential of the novel device is also presented.

  19. Generation of sub-two-cycle millijoule infrared pulses in an optical parametric chirped-pulse amplifier and their application to soft x-ray absorption spectroscopy with high-flux high harmonics

    NASA Astrophysics Data System (ADS)

    Ishii, Nobuhisa; Kaneshima, Keisuke; Kanai, Teruto; Watanabe, Shuntaro; Itatani, Jiro

    2018-01-01

    An optical parametric chirped-pulse amplifier (OPCPA) based on bismuth triborate (BiB3O6, BIBO) crystals has been developed to deliver 1.5 mJ, 10.1 fs optical pulses around 1.6 μm with a repetition rate of 1 kHz and a stable carrier-envelope phase. The seed and pump pulses of the BIBO-based OPCPA are provided from two Ti:sapphire chirped-pulse amplification (CPA) systems. In both CPA systems, transmission gratings are used in the stretchers and compressors that result in a high throughput and robust operation without causing any thermal problem and optical damage. The seed pulses of the OPCPA are generated by intrapulse frequency mixing of a spectrally broadened continuum, temporally stretched to approximately 5 ps then, and amplified to more than 1.5 mJ. The amplified pulses are compressed in a fused silica block down to 10.1 fs. This BIBO-based OPCPA has been applied to high-flux high harmonic generation beyond the carbon K edge at 284 eV. The high-flux soft-x-ray continuum allows measuring the x-ray absorption near-edge structure of the carbon K edge within 2 min, which is shorter than a typical measurement time using synchrotron-based light sources. This laser-based table-top soft-x-ray source is a promising candidate for ultrafast soft x-ray spectroscopy with femtosecond to attosecond time resolution.

  20. SPM analysis of parametric (R)-[11C]PK11195 binding images: plasma input versus reference tissue parametric methods.

    PubMed

    Schuitemaker, Alie; van Berckel, Bart N M; Kropholler, Marc A; Veltman, Dick J; Scheltens, Philip; Jonker, Cees; Lammertsma, Adriaan A; Boellaard, Ronald

    2007-05-01

    (R)-[11C]PK11195 has been used for quantifying cerebral microglial activation in vivo. In previous studies, both plasma input and reference tissue methods have been used, usually in combination with a region of interest (ROI) approach. Definition of ROIs, however, can be labourious and prone to interobserver variation. In addition, results are only obtained for predefined areas and (unexpected) signals in undefined areas may be missed. On the other hand, standard pharmacokinetic models are too sensitive to noise to calculate (R)-[11C]PK11195 binding on a voxel-by-voxel basis. Linearised versions of both plasma input and reference tissue models have been described, and these are more suitable for parametric imaging. The purpose of this study was to compare the performance of these plasma input and reference tissue parametric methods on the outcome of statistical parametric mapping (SPM) analysis of (R)-[11C]PK11195 binding. Dynamic (R)-[11C]PK11195 PET scans with arterial blood sampling were performed in 7 younger and 11 elderly healthy subjects. Parametric images of volume of distribution (Vd) and binding potential (BP) were generated using linearised versions of plasma input (Logan) and reference tissue (Reference Parametric Mapping) models. Images were compared at the group level using SPM with a two-sample t-test per voxel, both with and without proportional scaling. Parametric BP images without scaling provided the most sensitive framework for determining differences in (R)-[11C]PK11195 binding between younger and elderly subjects. Vd images could only demonstrate differences in (R)-[11C]PK11195 binding when analysed with proportional scaling due to intersubject variation in K1/k2 (blood-brain barrier transport and non-specific binding).

  1. Characterization of a multimode coplanar waveguide parametric amplifier

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simoen, M., E-mail: simoen@chalmers.se; Krantz, P.; Bylander, Jonas

    2015-10-21

    We characterize a Josephson parametric amplifier based on a flux-tunable quarter-wavelength resonator. The fundamental resonance frequency is ∼1 GHz, but we use higher modes of the resonator for our measurements. An on-chip tuning line allows for magnetic flux pumping of the amplifier. We investigate and compare degenerate parametric amplification, involving a single mode, and nondegenerate parametric amplification, using a pair of modes. We show that we reach quantum-limited noise performance in both cases.

  2. A Cartesian parametrization for the numerical analysis of material instability

    DOE PAGES

    Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.; ...

    2016-02-25

    We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, themore » performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.« less

  3. A Cartesian parametrization for the numerical analysis of material instability

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mota, Alejandro; Chen, Qiushi; Foulk, III, James W.

    We examine four parametrizations of the unit sphere in the context of material stability analysis by means of the singularity of the acoustic tensor. We then propose a Cartesian parametrization for vectors that lie a cube of side length two and use these vectors in lieu of unit normals to test for the loss of the ellipticity condition. This parametrization is then used to construct a tensor akin to the acoustic tensor. It is shown that both of these tensors become singular at the same time and in the same planes in the presence of a material instability. Furthermore, themore » performance of the Cartesian parametrization is compared against the other parametrizations, with the results of these comparisons showing that in general, the Cartesian parametrization is more robust and more numerically efficient than the others.« less

  4. Laser And Nonlinear Optical Materials For Laser Remote Sensing

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.

    2005-01-01

    NASA remote sensing missions involving laser systems and their economic impact are outlined. Potential remote sensing missions include: green house gasses, tropospheric winds, ozone, water vapor, and ice cap thickness. Systems to perform these measurements use lanthanide series lasers and nonlinear devices including second harmonic generators and parametric oscillators. Demands these missions place on the laser and nonlinear optical materials are discussed from a materials point of view. Methods of designing new laser and nonlinear optical materials to meet these demands are presented.

  5. Parametric Methods for Dynamic 11C-Phenytoin PET Studies.

    PubMed

    Mansor, Syahir; Yaqub, Maqsood; Boellaard, Ronald; Froklage, Femke E; de Vries, Anke; Bakker, Esther D M; Voskuyl, Rob A; Eriksson, Jonas; Schwarte, Lothar A; Verbeek, Joost; Windhorst, Albert D; Lammertsma, Adriaan A

    2017-03-01

    In this study, the performance of various methods for generating quantitative parametric images of dynamic 11 C-phenytoin PET studies was evaluated. Methods: Double-baseline 60-min dynamic 11 C-phenytoin PET studies, including online arterial sampling, were acquired for 6 healthy subjects. Parametric images were generated using Logan plot analysis, a basis function method, and spectral analysis. Parametric distribution volume (V T ) and influx rate ( K 1 ) were compared with those obtained from nonlinear regression analysis of time-activity curves. In addition, global and regional test-retest (TRT) variability was determined for parametric K 1 and V T values. Results: Biases in V T observed with all parametric methods were less than 5%. For K 1 , spectral analysis showed a negative bias of 16%. The mean TRT variabilities of V T and K 1 were less than 10% for all methods. Shortening the scan duration to 45 min provided similar V T and K 1 with comparable TRT performance compared with 60-min data. Conclusion: Among the various parametric methods tested, the basis function method provided parametric V T and K 1 values with the least bias compared with nonlinear regression data and showed TRT variabilities lower than 5%, also for smaller volume-of-interest sizes (i.e., higher noise levels) and shorter scan duration. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

  6. Parametric Modeling for Fluid Systems

    NASA Technical Reports Server (NTRS)

    Pizarro, Yaritzmar Rosario; Martinez, Jonathan

    2013-01-01

    Fluid Systems involves different projects that require parametric modeling, which is a model that maintains consistent relationships between elements as is manipulated. One of these projects is the Neo Liquid Propellant Testbed, which is part of Rocket U. As part of Rocket U (Rocket University), engineers at NASA's Kennedy Space Center in Florida have the opportunity to develop critical flight skills as they design, build and launch high-powered rockets. To build the Neo testbed; hardware from the Space Shuttle Program was repurposed. Modeling for Neo, included: fittings, valves, frames and tubing, between others. These models help in the review process, to make sure regulations are being followed. Another fluid systems project that required modeling is Plant Habitat's TCUI test project. Plant Habitat is a plan to develop a large growth chamber to learn the effects of long-duration microgravity exposure to plants in space. Work for this project included the design and modeling of a duct vent for flow test. Parametric Modeling for these projects was done using Creo Parametric 2.0.

  7. Extended parametric representation of compressor fans and turbines. Volume 2: Part user's manual (parametric turbine)

    NASA Technical Reports Server (NTRS)

    Coverse, G. L.

    1984-01-01

    A turbine modeling technique has been developed which will enable the user to obtain consistent and rapid off-design performance from design point input. This technique is applicable to both axial and radial flow turbine with flow sizes ranging from about one pound per second to several hundred pounds per second. The axial flow turbines may or may not include variable geometry in the first stage nozzle. A user-specified option will also permit the calculation of design point cooling flow levels and corresponding changes in efficiency for the axial flow turbines. The modeling technique has been incorporated into a time-sharing program in order to facilitate its use. Because this report contains a description of the input output data, values of typical inputs, and example cases, it is suitable as a user's manual. This report is the second of a three volume set. The titles of the three volumes are as follows: (1) Volume 1 CMGEN USER's Manual (Parametric Compressor Generator); (2) Volume 2 PART USER's Manual (Parametric Turbine); (3) Volume 3 MODFAN USER's Manual (Parametric Modulation Flow Fan).

  8. Marginally specified priors for non-parametric Bayesian estimation

    PubMed Central

    Kessler, David C.; Hoff, Peter D.; Dunson, David B.

    2014-01-01

    Summary Prior specification for non-parametric Bayesian inference involves the difficult task of quantifying prior knowledge about a parameter of high, often infinite, dimension. A statistician is unlikely to have informed opinions about all aspects of such a parameter but will have real information about functionals of the parameter, such as the population mean or variance. The paper proposes a new framework for non-parametric Bayes inference in which the prior distribution for a possibly infinite dimensional parameter is decomposed into two parts: an informative prior on a finite set of functionals, and a non-parametric conditional prior for the parameter given the functionals. Such priors can be easily constructed from standard non-parametric prior distributions in common use and inherit the large support of the standard priors on which they are based. Additionally, posterior approximations under these informative priors can generally be made via minor adjustments to existing Markov chain approximation algorithms for standard non-parametric prior distributions. We illustrate the use of such priors in the context of multivariate density estimation using Dirichlet process mixture models, and in the modelling of high dimensional sparse contingency tables. PMID:25663813

  9. Incorporating parametric uncertainty into population viability analysis models

    USGS Publications Warehouse

    McGowan, Conor P.; Runge, Michael C.; Larson, Michael A.

    2011-01-01

    Uncertainty in parameter estimates from sampling variation or expert judgment can introduce substantial uncertainty into ecological predictions based on those estimates. However, in standard population viability analyses, one of the most widely used tools for managing plant, fish and wildlife populations, parametric uncertainty is often ignored in or discarded from model projections. We present a method for explicitly incorporating this source of uncertainty into population models to fully account for risk in management and decision contexts. Our method involves a two-step simulation process where parametric uncertainty is incorporated into the replication loop of the model and temporal variance is incorporated into the loop for time steps in the model. Using the piping plover, a federally threatened shorebird in the USA and Canada, as an example, we compare abundance projections and extinction probabilities from simulations that exclude and include parametric uncertainty. Although final abundance was very low for all sets of simulations, estimated extinction risk was much greater for the simulation that incorporated parametric uncertainty in the replication loop. Decisions about species conservation (e.g., listing, delisting, and jeopardy) might differ greatly depending on the treatment of parametric uncertainty in population models.

  10. Real-time Kalman filter: Cooling of an optically levitated nanoparticle

    NASA Astrophysics Data System (ADS)

    Setter, Ashley; Toroš, Marko; Ralph, Jason F.; Ulbricht, Hendrik

    2018-03-01

    We demonstrate that a Kalman filter applied to estimate the position of an optically levitated nanoparticle, and operated in real-time within a field programmable gate array, is sufficient to perform closed-loop parametric feedback cooling of the center-of-mass motion to sub-Kelvin temperatures. The translational center-of-mass motion along the optical axis of the trapped nanoparticle has been cooled by 3 orders of magnitude, from a temperature of 300 K to a temperature of 162 ±15 mK.

  11. Parametric instability induced by X-mode wave heating at EISCAT

    NASA Astrophysics Data System (ADS)

    Wang, Xiang; Zhou, Chen; Liu, Moran; Honary, Farideh; Ni, Binbin; Zhao, Zhengyu

    2016-10-01

    In this paper, we present results of parametric instability induced by X-mode wave heating observed by EISCAT (European Incoherent Scatter Scientific Association) radar at Tromsø, Norway. Three typical X-mode ionospheric heating experiments on 22 October 2013, 19 October 2012, and 21 February 2013 are investigated in details. Both parametric decay instability (PDI) and oscillating two-stream instability are observed during the X-mode heating period. We suggest that the full dispersion relationship of the Langmuir wave can be employed to analyze the X-mode parametric instability excitation. A modified kinetic electron distribution is proposed and analyzed, which is able to satisfy the matching condition of parametric instability excitation. Parallel electric field component of X-mode heating wave can also exceed the parametric instability excitation threshold under certain conditions.

  12. Modeling the directivity of parametric loudspeaker

    NASA Astrophysics Data System (ADS)

    Shi, Chuang; Gan, Woon-Seng

    2012-09-01

    The emerging applications of the parametric loudspeaker, such as 3D audio, demands accurate directivity control at the audible frequency (i.e. the difference frequency). Though the delay-and-sum beamforming has been proven adequate to adjust the steering angles of the parametric loudspeaker, accurate prediction of the mainlobe and sidelobes remains a challenging problem. It is mainly because of the approximations that are used to derive the directivity of the difference frequency from the directivity of the primary frequency, and the mismatches between the theoretical directivity and the measured directivity caused by system errors incurred at different stages of the implementation. In this paper, we propose a directivity model of the parametric loudspeaker. The directivity model consists of two tuning vectors corresponding to the spacing error and the weight error for the primary frequency. The directivity model adopts a modified form of the product directivity principle for the difference frequency to further improve the modeling accuracy.

  13. Observational Signatures of Parametric Instability at 1AU

    NASA Astrophysics Data System (ADS)

    Bowen, T. A.; Bale, S. D.; Badman, S.

    2017-12-01

    Observations and simulations of inertial compressive turbulence in the solar wind are characterized by density structures anti-correlated with magnetic fluctuations parallel to the mean field. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures (PBS), kinetic ion acoustic waves, as well as the MHD slow mode. Recent work, specifically Verscharen et al. (2017), has highlighted the unexpected fluid like nature of the solar wind. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggests the presence of a driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the parametric instability, in which large amplitude Alfvenic fluctuations decay into parallel propagating compressive waves. This work employs 10 years of WIND observations in order to test the parametric decay process as a source of compressive waves in the solar wind through comparing collisionless damping rates of compressive fluctuations with growth rates of the parametric instability. Preliminary results suggest that generation of compressive waves through parametric decay is overdamped at 1 AU. However, the higher parametric decay rates expected in the inner heliosphere likely allow for growth of the slow mode-the remnants of which could explain density fluctuations observed at 1AU.

  14. The degenerate parametric oscillator and Ince's equation

    NASA Astrophysics Data System (ADS)

    Cordero-Soto, Ricardo; Suslov, Sergei K.

    2011-01-01

    We construct Green's function for the quantum degenerate parametric oscillator in the coordinate representation in terms of standard solutions of Ince's equation in a framework of a general approach to variable quadratic Hamiltonians. Exact time-dependent wavefunctions and their connections with dynamical invariants and SU(1, 1) group are also discussed. An extension to the degenerate parametric oscillator with time-dependent amplitude and phase is also mentioned.

  15. (2 + 1)-dimensional bright optical solitons in metamaterials with Kerr, power and parabolic law nonlinearities

    NASA Astrophysics Data System (ADS)

    Boubir, Badreddine

    2018-06-01

    In this paper, we investigate the dynamics of bright optical solitons in nonlinear metamaterials governed by a (2 + 1)-dimensional nonlinear Schrödinger equation. Three types of nonlinearities have been considered, Kerr law, power law and parabolic law. We based on the solitary wave ansatz method to find these optical soliton solutions. All necessary parametric conditions for their existence are driven.

  16. Stochastic stability of parametrically excited random systems

    NASA Astrophysics Data System (ADS)

    Labou, M.

    2004-01-01

    Multidegree-of-freedom dynamic systems subjected to parametric excitation are analyzed for stochastic stability. The variation of excitation intensity with time is described by the sum of a harmonic function and a stationary random process. The stability boundaries are determined by the stochastic averaging method. The effect of random parametric excitation on the stability of trivial solutions of systems of differential equations for the moments of phase variables is studied. It is assumed that the frequency of harmonic component falls within the region of combination resonances. Stability conditions for the first and second moments are obtained. It turns out that additional parametric excitation may have a stabilizing or destabilizing effect, depending on the values of certain parameters of random excitation. As an example, the stability of a beam in plane bending is analyzed.

  17. Effects of polarization mode dispersion on polarization-entangled photons generated via broadband pumped spontaneous parametric down-conversion

    PubMed Central

    Lim, Hyang-Tag; Hong, Kang-Hee; Kim, Yoon-Ho

    2016-01-01

    An inexpensive and compact frequency multi-mode diode laser enables a compact two-photon polarization entanglement source via the continuous wave broadband pumped spontaneous parametric down-conversion (SPDC) process. Entanglement degradation caused by polarization mode dispersion (PMD) is one of the critical issues in optical fiber-based polarization entanglement distribution. We theoretically and experimentally investigate how the initial entanglement is degraded when the two-photon polarization entangled state undergoes PMD. We report an effect of PMD unique to broadband pumped SPDC, equally applicable to pulsed pumping as well as cw broadband pumping, which is that the amount of the entanglement degradation is asymmetrical to the PMD introduced to each quantum channel. We believe that our results have important applications in long-distance distribution of polarization entanglement via optical fiber channels. PMID:27174100

  18. Manipulation of metal-dielectric core-shell particles in optical fields

    NASA Astrophysics Data System (ADS)

    Chvátal, Lukáš; Šiler, Martin; Zemánek, Pavel

    2014-12-01

    Metal-dielectric core-shell particles represent promising tools in nanoplasmonics. In combination with optical tweezers they can be manipulated in a contactless way through fluid and their plasmonic properties can be used to probe or modify the local environment. We perform a numerical parametric study to find the particle geometry and material parameters under which such particle can be stably confined in optical tweezers. We use the theory based on Mie scattering in the focal field of an ideal water immersion objective of numerical aperture NA=1.2. For very thin metal layers we find that strong trapping on the optical axis can be achieved.

  19. Optical frequency comb Faraday rotation spectroscopy

    NASA Astrophysics Data System (ADS)

    Johansson, Alexandra C.; Westberg, Jonas; Wysocki, Gerard; Foltynowicz, Aleksandra

    2018-05-01

    We demonstrate optical frequency comb Faraday rotation spectroscopy (OFC-FRS) for broadband interference-free detection of paramagnetic species. The system is based on a femtosecond doubly resonant optical parametric oscillator and a fast-scanning Fourier transform spectrometer (FTS). The sample is placed in a DC magnetic field parallel to the light propagation. Efficient background suppression is implemented via switching the direction of the field on consecutive FTS scans and subtracting the consecutive spectra, which enables long-term averaging. In this first demonstration, we measure the entire Q- and R-branches of the fundamental band of nitric oxide in the 5.2-5.4 µm range and achieve good agreement with a theoretical model.

  20. Rayleigh-type parametric chemical oscillation.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

  1. Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke

    PubMed Central

    Srinivasan, Vivek J.; Mandeville, Emiri T.; Can, Anil; Blasi, Francesco; Climov, Mihail; Daneshmand, Ali; Lee, Jeong Hyun; Yu, Esther; Radhakrishnan, Harsha; Lo, Eng H.; Sakadžić, Sava; Eikermann-Haerter, Katharina; Ayata, Cenk

    2013-01-01

    Progress in experimental stroke and translational medicine could be accelerated by high-resolution in vivo imaging of disease progression in the mouse cortex. Here, we introduce optical microscopic methods that monitor brain injury progression using intrinsic optical scattering properties of cortical tissue. A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described. In the acute stages, the spatiotemporal interplay between hemodynamics and cell viability, a key determinant of pathogenesis, was imaged. In acute stroke, microscopic biomarkers for eventual infarction, including capillary non-perfusion, cerebral blood flow deficiency, altered cellular scattering, and impaired autoregulation of cerebral blood flow, were quantified and correlated with histology. Additionally, longitudinal microscopy revealed remodeling and flow recovery after one week of chronic stroke. Intrinsic scattering properties serve as reporters of acute cellular and vascular injury and recovery in experimental stroke. Multi-parametric OCT represents a robust in vivo imaging platform to comprehensively investigate these properties. PMID:23940761

  2. Parametric amplification in a resonant sensing array

    NASA Astrophysics Data System (ADS)

    Yie, Zi; Miller, Nicholas J.; Shaw, Steven W.; Turner, Kimberly L.

    2012-03-01

    We demonstrate parametric amplification of a multidegree of freedom resonant mass sensing array via an applied base motion containing the appropriate frequency content and phases. Applying parametric forcing in this manner is simple and aligns naturally with the vibrational properties of the sensing structure. Using this technique, we observe an increase in the quality factors of the coupled array resonances, which provides an effective means of improving device sensitivity.

  3. Towards an Empirically Based Parametric Explosion Spectral Model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ford, S R; Walter, W R; Ruppert, S

    2009-08-31

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before been tested. The focus of our work is on the local and regional distances (< 2000 km) and phases (Pn, Pg, Sn, Lg) necessary to see small explosions. We are developing a parametric model of the nuclear explosion seismic source spectrum that is compatible with the earthquake-based geometrical spreading and attenuation models developed using the Magnitude Distance Amplitude Correction (MDAC) techniques (Walter and Taylor, 2002). The explosion parametric model will be particularly important in regions without any priormore » explosion data for calibration. The model is being developed using the available body of seismic data at local and regional distances for past nuclear explosions at foreign and domestic test sites. Parametric modeling is a simple and practical approach for widespread monitoring applications, prior to the capability to carry out fully deterministic modeling. The achievable goal of our parametric model development is to be able to predict observed local and regional distance seismic amplitudes for event identification and yield determination in regions with incomplete or no prior history of underground nuclear testing. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.« less

  4. A capacitive ultrasonic transducer based on parametric resonance.

    PubMed

    Surappa, Sushruta; Satir, Sarp; Levent Degertekin, F

    2017-07-24

    A capacitive ultrasonic transducer based on a parametric resonator structure is described and experimentally demonstrated. The transducer structure, which we call capacitive parametric ultrasonic transducer (CPUT), uses a parallel plate capacitor with a movable membrane as part of a degenerate parametric series RLC resonator circuit with a resonance frequency of f o . When the capacitor plate is driven with an incident harmonic ultrasonic wave at the pump frequency of 2f o with sufficient amplitude, the RLC circuit becomes unstable and ultrasonic energy can be efficiently converted to an electrical signal at f o frequency in the RLC circuit. An important characteristic of the CPUT is that unlike other electrostatic transducers, it does not require DC bias or permanent charging to be used as a receiver. We describe the operation of the CPUT using an analytical model and numerical simulations, which shows drive amplitude dependent operation regimes including parametric resonance when a certain threshold is exceeded. We verify these predictions by experiments with a micromachined membrane based capacitor structure in immersion where ultrasonic waves incident at 4.28 MHz parametrically drive a signal with significant amplitude in the 2.14 MHz RLC circuit. With its unique features, the CPUT can be particularly advantageous for applications such as wireless power transfer for biomedical implants and acoustic sensing.

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  6. Linear optical properties of the monoclinic bismuth borate BiB3O6

    NASA Astrophysics Data System (ADS)

    Hellwig, H.; Liebertz, J.; Bohatý, L.

    2000-07-01

    New materials for nonlinear optical (NLO) applications are still of great interest. The monoclinic BiB3O6 (BIBO) shows exceptionally large NLO coefficients. In this article we will present the linear optical properties in the wavelength range between 350 and 2400 nm, the phase matching conditions calculated for second harmonic generation, and optical parametric oscillation. Angular bandwidth data are also given. The wide tuning range of phase matched directions together with the monoclinic symmetry allow a broad variety of applications. The laser damage threshold is comparable to high quality lithium triborate.

  7. A general framework for parametric survival analysis.

    PubMed

    Crowther, Michael J; Lambert, Paul C

    2014-12-30

    Parametric survival models are being increasingly used as an alternative to the Cox model in biomedical research. Through direct modelling of the baseline hazard function, we can gain greater understanding of the risk profile of patients over time, obtaining absolute measures of risk. Commonly used parametric survival models, such as the Weibull, make restrictive assumptions of the baseline hazard function, such as monotonicity, which is often violated in clinical datasets. In this article, we extend the general framework of parametric survival models proposed by Crowther and Lambert (Journal of Statistical Software 53:12, 2013), to incorporate relative survival, and robust and cluster robust standard errors. We describe the general framework through three applications to clinical datasets, in particular, illustrating the use of restricted cubic splines, modelled on the log hazard scale, to provide a highly flexible survival modelling framework. Through the use of restricted cubic splines, we can derive the cumulative hazard function analytically beyond the boundary knots, resulting in a combined analytic/numerical approach, which substantially improves the estimation process compared with only using numerical integration. User-friendly Stata software is provided, which significantly extends parametric survival models available in standard software. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Modeling personnel turnover in the parametric organization

    NASA Technical Reports Server (NTRS)

    Dean, Edwin B.

    1991-01-01

    A model is developed for simulating the dynamics of a newly formed organization, credible during all phases of organizational development. The model development process is broken down into the activities of determining the tasks required for parametric cost analysis (PCA), determining the skills required for each PCA task, determining the skills available in the applicant marketplace, determining the structure of the model, implementing the model, and testing it. The model, parameterized by the likelihood of job function transition, has demonstrated by the capability to represent the transition of personnel across functional boundaries within a parametric organization using a linear dynamical system, and the ability to predict required staffing profiles to meet functional needs at the desired time. The model can be extended by revisions of the state and transition structure to provide refinements in functional definition for the parametric and extended organization.

  9. A Parametric Oscillator Experiment for Undergraduates

    NASA Astrophysics Data System (ADS)

    Huff, Alison; Thompson, Johnathon; Pate, Jacob; Kim, Hannah; Chiao, Raymond; Sharping, Jay

    We describe an upper-division undergraduate-level analytic mechanics experiment or classroom demonstration of a weakly-damped pendulum driven into parametric resonance. Students can derive the equations of motion from first principles and extract key oscillator features, such as quality factor and parametric gain, from experimental data. The apparatus is compact, portable and easily constructed from inexpensive components. Motion control and data acquisition are accomplished using an Arduino micro-controller incorporating a servo motor, laser sensor, and data logger. We record the passage time of the pendulum through its equilibrium position and obtain the maximum speed per oscillation as a function of time. As examples of the interesting physics which the experiment reveals, we present contour plots depicting the energy of the system as functions of driven frequency and modulation depth. We observe the transition to steady state oscillation and compare the experimental oscillation threshold with theoretical expectations. A thorough understanding of this hands-on laboratory exercise provides a foundation for current research in quantum information and opto-mechanics, where damped harmonic motion, quality factor, and parametric amplification are central.

  10. Parametric Cost Models for Space Telescopes

    NASA Technical Reports Server (NTRS)

    Stahl, H. Philip; Henrichs, Todd; Dollinger, Courtney

    2010-01-01

    Multivariable parametric cost models for space telescopes provide several benefits to designers and space system project managers. They identify major architectural cost drivers and allow high-level design trades. They enable cost-benefit analysis for technology development investment. And, they provide a basis for estimating total project cost. A survey of historical models found that there is no definitive space telescope cost model. In fact, published models vary greatly [1]. Thus, there is a need for parametric space telescopes cost models. An effort is underway to develop single variable [2] and multi-variable [3] parametric space telescope cost models based on the latest available data and applying rigorous analytical techniques. Specific cost estimating relationships (CERs) have been developed which show that aperture diameter is the primary cost driver for large space telescopes; technology development as a function of time reduces cost at the rate of 50% per 17 years; it costs less per square meter of collecting aperture to build a large telescope than a small telescope; and increasing mass reduces cost.

  11. The impact of parametrized convection on cloud feedback.

    PubMed

    Webb, Mark J; Lock, Adrian P; Bretherton, Christopher S; Bony, Sandrine; Cole, Jason N S; Idelkadi, Abderrahmane; Kang, Sarah M; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D; Zhao, Ming

    2015-11-13

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that 'ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback

  12. Machine learning-based dual-energy CT parametric mapping

    NASA Astrophysics Data System (ADS)

    Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W.; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Helo, Rose Al; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C.; Rassouli, Negin; Gilkeson, Robert C.; Traughber, Bryan J.; Cheng, Chee-Wai; Muzic, Raymond F., Jr.

    2018-06-01

    The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Zeff), relative electron density (ρ e), mean excitation energy (I x ), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 s. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency.

  13. Machine learning-based dual-energy CT parametric mapping.

    PubMed

    Su, Kuan-Hao; Kuo, Jung-Wen; Jordan, David W; Van Hedent, Steven; Klahr, Paul; Wei, Zhouping; Al Helo, Rose; Liang, Fan; Qian, Pengjiang; Pereira, Gisele C; Rassouli, Negin; Gilkeson, Robert C; Traughber, Bryan J; Cheng, Chee-Wai; Muzic, Raymond F

    2018-06-08

    The aim is to develop and evaluate machine learning methods for generating quantitative parametric maps of effective atomic number (Z eff ), relative electron density (ρ e ), mean excitation energy (I x ), and relative stopping power (RSP) from clinical dual-energy CT data. The maps could be used for material identification and radiation dose calculation. Machine learning methods of historical centroid (HC), random forest (RF), and artificial neural networks (ANN) were used to learn the relationship between dual-energy CT input data and ideal output parametric maps calculated for phantoms from the known compositions of 13 tissue substitutes. After training and model selection steps, the machine learning predictors were used to generate parametric maps from independent phantom and patient input data. Precision and accuracy were evaluated using the ideal maps. This process was repeated for a range of exposure doses, and performance was compared to that of the clinically-used dual-energy, physics-based method which served as the reference. The machine learning methods generated more accurate and precise parametric maps than those obtained using the reference method. Their performance advantage was particularly evident when using data from the lowest exposure, one-fifth of a typical clinical abdomen CT acquisition. The RF method achieved the greatest accuracy. In comparison, the ANN method was only 1% less accurate but had much better computational efficiency than RF, being able to produce parametric maps in 15 s. Machine learning methods outperformed the reference method in terms of accuracy and noise tolerance when generating parametric maps, encouraging further exploration of the techniques. Among the methods we evaluated, ANN is the most suitable for clinical use due to its combination of accuracy, excellent low-noise performance, and computational efficiency.

  14. The impact of parametrized convection on cloud feedback

    PubMed Central

    Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

    2015-01-01

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

  15. Direct Estimation of Kinetic Parametric Images for Dynamic PET

    PubMed Central

    Wang, Guobao; Qi, Jinyi

    2013-01-01

    Dynamic positron emission tomography (PET) can monitor spatiotemporal distribution of radiotracer in vivo. The spatiotemporal information can be used to estimate parametric images of radiotracer kinetics that are of physiological and biochemical interests. Direct estimation of parametric images from raw projection data allows accurate noise modeling and has been shown to offer better image quality than conventional indirect methods, which reconstruct a sequence of PET images first and then perform tracer kinetic modeling pixel-by-pixel. Direct reconstruction of parametric images has gained increasing interests with the advances in computing hardware. Many direct reconstruction algorithms have been developed for different kinetic models. In this paper we review the recent progress in the development of direct reconstruction algorithms for parametric image estimation. Algorithms for linear and nonlinear kinetic models are described and their properties are discussed. PMID:24396500

  16. Investigation of laser induced parametric interactions in optical waveguides and fibers

    NASA Technical Reports Server (NTRS)

    Yu, C.

    1978-01-01

    Experimental and theoretical aspects of the laser pump depletion characteristics in an optical fiber due to stimulated Raman scattering, and stimulated Brillouin scattering were studied. A review is presented of research in fiber transmission accompanied by stimulated scattering. Results of experimental work with tunable dye lasers and argon lasers are presented. The spectral profiles of the laser pump and its transmitted light through the fiber are given.

  17. Exponentially Enhanced Light-Matter Interaction, Cooperativities, and Steady-State Entanglement Using Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Qin, Wei; Miranowicz, Adam; Li, Peng-Bo; Lü, Xin-You; You, J. Q.; Nori, Franco

    2018-03-01

    We propose an experimentally feasible method for enhancing the atom-field coupling as well as the ratio between this coupling and dissipation (i.e., cooperativity) in an optical cavity. It exploits optical parametric amplification to exponentially enhance the atom-cavity interaction and, hence, the cooperativity of the system, with the squeezing-induced noise being completely eliminated. Consequently, the atom-cavity system can be driven from the weak-coupling regime to the strong-coupling regime for modest squeezing parameters, and even can achieve an effective cooperativity much larger than 100. Based on this, we further demonstrate the generation of steady-state nearly maximal quantum entanglement. The resulting entanglement infidelity (which quantifies the deviation of the actual state from a maximally entangled state) is exponentially smaller than the lower bound on the infidelities obtained in other dissipative entanglement preparations without applying squeezing. In principle, we can make an arbitrarily small infidelity. Our generic method for enhancing atom-cavity interaction and cooperativities can be implemented in a wide range of physical systems, and it can provide diverse applications for quantum information processing.

  18. Optical realization of optimal symmetric real state quantum cloning machine

    NASA Astrophysics Data System (ADS)

    Hu, Gui-Yu; Zhang, Wen-Hai; Ye, Liu

    2010-01-01

    We present an experimentally uniform linear optical scheme to implement the optimal 1→2 symmetric and optimal 1→3 symmetric economical real state quantum cloning machine of the polarization state of the single photon. This scheme requires single-photon sources and two-photon polarization entangled state as input states. It also involves linear optical elements and three-photon coincidence. Then we consider the realistic realization of the scheme by using the parametric down-conversion as photon resources. It is shown that under certain condition, the scheme is feasible by current experimental technology.

  19. Electro-optic sampling of near-infrared waveforms

    NASA Astrophysics Data System (ADS)

    Keiber, Sabine; Sederberg, Shawn; Schwarz, Alexander; Trubetskov, Michael; Pervak, Volodymyr; Krausz, Ferenc; Karpowicz, Nicholas

    2016-03-01

    Access to the complete electric field evolution of a laser pulse is essential for attosecond science in general, and for the scrutiny and control of electron phenomena in solid-state physics specifically. Time-resolved field measurements are routine in the terahertz spectral range, using electro-optic sampling (EOS), photoconductive switches and field-induced second harmonic generation. EOS in particular features outstanding sensitivity and ease of use, making it the basis of time-resolved spectroscopic measurements for studying charge carrier dynamics and active optical devices. In this Letter, we show that careful optical filtering allows the bandwidth of this technique to be extended to wavelengths as short as 1.2 μm (230 THz) with half-cycle durations 2.3 times shorter than the sampling pulse. In a proof-of-principle application, we measure the influence of optical parametric amplification (OPA) on the electric field dynamics of a few-cycle near-infrared (NIR) pulse.

  20. Parametric instabilities of rotor-support systems with application to industrial ventilators

    NASA Technical Reports Server (NTRS)

    Parszewski, Z.; Krodkiemski, T.; Marynowski, K.

    1980-01-01

    Rotor support systems interaction with parametric excitation is considered for both unequal principal shaft stiffness (generators) and offset disc rotors (ventilators). Instability regions and types of instability are computed in the first case, and parametric resonances in the second case. Computed and experimental results are compared for laboratory machine models. A field case study of parametric vibrations in industrial ventilators is reported. Computed parametric resonances are confirmed in field measurements, and some industrial failures are explained. Also the dynamic influence and gyroscopic effect of supporting structures are shown and computed.

  1. Low Noise Frequency Comb Sources Based on Synchronously Pumped Doubly Resonant Optical Parametric Oscillators

    NASA Astrophysics Data System (ADS)

    Wan, Chenchen

    Optical frequency combs are coherent light sources consist of thousands of equally spaced frequency lines. Frequency combs have achieved success in applications of metrology, spectroscopy and precise pulse manipulation and control. The most common way to generate frequency combs is based on mode-locked lasers which has the output spectrum of comb structures. To generate stable frequency combs, the output from mode-locked lasers need to be phase stabilized. The whole comb lines will be stabilized if the pulse train repetition rate corresponding to comb spacing and the pulse carrier envelope offset (CEO) frequency are both stabilized. The output from a laser always has fluctuations in parameters known as noise. In laser applications, noise is an important factor to limit the performance and often need to be well controlled. For example in precision measurement such as frequency metrology and precise spectroscopy, low laser intensity and phase noise is required. In mode-locked lasers there are different types of noise like intensity noise, pulse temporal position noise also known as timing jitter, optical phase noise. In term for frequency combs, these noise dynamics is more complex and often related. Understanding the noise behavior is not only of great interest in practical applications but also help understand fundamental laser physics. In this dissertation, the noise of frequency combs and mode-locked lasers will be studied in two projects. First, the CEO frequency phase noise of a synchronously pumped doubly resonant optical parametric oscillators (OPO) will be explored. This is very important for applications of the OPO as a coherent frequency comb source. Another project will focus on the intensity noise coupling in a soliton fiber oscillator, the finding of different noise coupling in soliton pulses and the dispersive waves generated from soliton perturbation can provide very practical guidance for low noise soliton laser design. OPOs are used to generate

  2. Problems of the design of low-noise input devices. [parametric amplifiers

    NASA Technical Reports Server (NTRS)

    Manokhin, V. M.; Nemlikher, Y. A.; Strukov, I. A.; Sharfov, Y. A.

    1974-01-01

    An analysis is given of the requirements placed on the elements of parametric centimeter waveband amplifiers for achievement of minimal noise temperatures. A low-noise semiconductor parametric amplifier using germanium parametric diodes for a receiver operating in the 4 GHz band was developed and tested confirming the possibility of satisfying all requirements.

  3. Noise-enhanced Parametric Resonance in Perturbed Galaxies

    NASA Astrophysics Data System (ADS)

    Sideris, Ioannis V.; Kandrup, Henry E.

    2004-02-01

    This paper describes how parametric resonances associated with a galactic potential subjected to relatively low-amplitude, strictly periodic time-dependent perturbations can be impacted by pseudo-random variations in the pulsation frequency, modeled as colored noise. One aim thereby is to allow for the effects of a changing oscillation frequency as the density distribution associated with a galaxy evolves during violent relaxation. Another is to mimic the possible effects of internal substructures, satellite galaxies, and/or a high-density environment. The principal conclusions are that allowing for a variable frequency does not vitiate the effects of parametric resonance, and that, in at least some cases, such variations can increase the overall importance of parametric resonance associated with systematic pulsations. In memory of Professor H. E. Kandrup, a brilliant scientist, excellent teacher, and good friend. His genius and sense of humor will be greatly missed.

  4. Josephson Parametric Reflection Amplifier with Integrated Directionality

    NASA Astrophysics Data System (ADS)

    Westig, M. P.; Klapwijk, T. M.

    2018-06-01

    A directional superconducting parametric amplifier in the GHz frequency range is designed and analyzed, suitable for low-power read-out of microwave kinetic inductance detectors employed in astrophysics and when combined with a nonreciprocal device at its input also for circuit quantum electrodynamics. It consists of a one-wavelength-long nondegenerate Josephson parametric reflection amplifier circuit. The device has two Josephson-junction oscillators, connected via a tailored impedance to an on-chip passive circuit which directs the in- to the output port. The amplifier provides a gain of 20 dB over a bandwidth of 220 MHz on the signal as well as on the idler portion of the amplified input and the total photon shot noise referred to the input corresponds to maximally approximately 1.3 photons per second per Hertz of bandwidth. We predict a factor of 4 increase in dynamic range compared to conventional Josephson parametric amplifiers.

  5. Quantization of simple parametrized systems

    NASA Astrophysics Data System (ADS)

    Ruffini, G.

    2005-11-01

    I study the canonical formulation and quantization of some simple parametrized systems, including the non-relativistic parametrized particle and the relativistic parametrized particle. Using Dirac's formalism I construct for each case the classical reduced phase space and study the dependence on the gauge fixing used. Two separate features of these systems can make this construction difficult: the actions are not invariant at the boundaries, and the constraints may have disconnected solution spaces. The relativistic particle is affected by both, while the non-relativistic particle displays only by the first. Analyzing the role of canonical transformations in the reduced phase space, I show that a change of gauge fixing is equivalent to a canonical transformation. In the relativistic case, quantization of one branch of the constraint at the time is applied and I analyze the electromagenetic backgrounds in which it is possible to quantize simultaneously both branches and still obtain a covariant unitary quantum theory. To preserve unitarity and space-time covariance, second quantization is needed unless there is no electric field. I motivate a definition of the inner product in all these cases and derive the Klein-Gordon inner product for the relativistic case. I construct phase space path integral representations for amplitudes for the BFV and the Faddeev path integrals, from which the path integrals in coordinate space (Faddeev-Popov and geometric path integrals) are derived.

  6. Correlation and squeezing for optical transistor and intensity router applications in diamond NV center.

    PubMed

    Ahmed, Noor; Khan, Ghulam Abbas; Wang, Ruimin; Hou, Jingru; Gong, Rui; Yang, Lingmeng; Zhang, Yanpeng

    2017-05-01

    We study an optical transistor (switch and amplifier) and router by spontaneous parametric four-wave mixing and fluorescence in diamond nitrogen-vacancy (NV) center. The routing results from three peaks of fluorescence signal in the time domain, while the switching and amplification are realized by correlation and squeezing. The intensity switching speed is about 17 ns. The optical transistor and router are controlled by the power of incident beams. Our experimental results provide that the advance technique of peak division and channel equalization ratio of about 90% are applicable to all optical switching and routing.

  7. Acceleration of the direct reconstruction of linear parametric images using nested algorithms.

    PubMed

    Wang, Guobao; Qi, Jinyi

    2010-03-07

    Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

  8. Correlation and squeezing for optical transistor and intensity for router applications in Pr3+:YSO.

    PubMed

    Khan, Ghulam Abbas; Li, Changbiao; Raza, Faizan; Ahmed, Noor; Mahesar, Abdul Rasheed; Ahmed, Irfan; Zhang, Yanpeng

    2017-06-14

    We realized an optical transistor and router utilizing multi-order fluorescence and spontaneous parametric four-wave mixing. Specifically, the optical routing action was derived from the results of splitting in the intensity signal due to a dressing effect, whereas the transistor as a switch and amplifier was realized by a switching correlation and squeezing via a nonlinear phase. A substantial enhancement of the optical contrast was observed for switching applications using correlation and squeezing contrary to the intensity signal. Moreover, the controlling parameters were also configured to devise a control mechanism for the optical transistor and router.

  9. Parametric Amplifier and Oscillator Based on Josephson Junction Circuitry

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Koshino, K.; Nakamura, Y.

    While the demand for low-noise amplification is ubiquitous, applications where the quantum-limited noise performance is indispensable are not very common. Microwave parametric amplifiers with near quantum-limited noise performance were first demonstrated more than 20 years ago. However, there had been little effort until recently to improve the performance or the ease of use of these amplifiers, partly because of a lack of any urgent motivation. The emergence of the field of quantum information processing in superconducting systems has changed this situation dramatically. The need to reliably read out the state of a given qubit using a very weak microwave probe within a very short time has led to renewed interest in these quantum-limited microwave amplifiers, which are already widely used as tools in this field. Here, we describe the quantum mechanical theory for one particular parametric amplifier design, called the flux-driven Josephson parametric amplifier, which we developed in 2008. The theory predicts the performance of this parametric amplifier, including its gain, bandwidth, and noise temperature. We also present the phase detection capability of this amplifier when it is operated with a pump power that is above the threshold, i.e., as a parametric phase-locked oscillator or parametron.

  10. Parametric number covariance in quantum chaotic spectra.

    PubMed

    Vinayak; Kumar, Sandeep; Pandey, Akhilesh

    2016-03-01

    We study spectral parametric correlations in quantum chaotic systems and introduce the number covariance as a measure of such correlations. We derive analytic results for the classical random matrix ensembles using the binary correlation method and obtain compact expressions for the covariance. We illustrate the universality of this measure by presenting the spectral analysis of the quantum kicked rotors for the time-reversal invariant and time-reversal noninvariant cases. A local version of the parametric number variance introduced earlier is also investigated.

  11. Towards a versatile active wavelength converter for all-optical networks based on quasi-phase matched intra-cavity difference-frequency generation.

    PubMed

    Torregrosa, Adrián J; Maestre, Haroldo; Capmany, Juan

    2013-11-18

    The availability of reconfigurable all-optical wavelength converters for an efficient and flexible use of optical resources in WDM (wavelength division multiplexing) networks is still lacking at present. We propose and report preliminary results on a versatile active technique for multiple and tunable wavelength conversions in the 1500-1700 nm spectral region. The technique is based on combining broadband quasi-phase matched intra-cavity parametric single-pass difference-frequency generation close to degeneracy in a diode-pumped tunable laser. A periodically poled stoichiometric lithium tantalate crystal is used as the nonlinear medium, with a parametric pump wave generated in a continuous-wave self-injection locked Cr3+:LiCAF tunable laser operating at around 800 nm.

  12. Multiphoton correlations in parametric down-conversion and their measurement in the pulsed regime

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ivanova, O A; Iskhakov, T Sh; Penin, A N

    2006-10-31

    We consider normalised intensity correlation functions (CFs) of different orders for light emitted via parametric down-conversion (PDC) and their dependence on the number of photons per mode. The main problem in measuring such correlation functions is their extremely small width, which considerably reduces their contrast. It is shown that if the radiation under study is modulated by a periodic sequence of pulses that are short compared to the CF width, no decrease in the contrast occurs. A procedure is proposed for measuring normalised CFs of various orders in the pulsed regime. For nanosecond-pulsed PDC radiation, normalised second-order CF is measuredmore » experimentally as a function of the mean photon number. (nonlinear optical phenomena)« less

  13. Comparisons between conventional optical imaging and parametric indirect microscopic imaging on human skin detection

    NASA Astrophysics Data System (ADS)

    Liu, Guoyan; Gao, Kun; Liu, Xuefeng; Ni, Guoqiang

    2016-10-01

    We report a new method, polarization parameters indirect microscopic imaging with a high transmission infrared light source, to detect the morphology and component of human skin. A conventional reflection microscopic system is used as the basic optical system, into which a polarization-modulation mechanics is inserted and a high transmission infrared light source is utilized. The near-field structural characteristics of human skin can be delivered by infrared waves and material coupling. According to coupling and conduction physics, changes of the optical wave parameters can be calculated and curves of the intensity of the image can be obtained. By analyzing the near-field polarization parameters in nanoscale, we can finally get the inversion images of human skin. Compared with the conventional direct optical microscope, this method can break diffraction limit and achieve a super resolution of sub-100nm. Besides, the method is more sensitive to the edges, wrinkles, boundaries and impurity particles.

  14. Parametric amplification and bidirectional invisibility in PT -symmetric time-Floquet systems

    NASA Astrophysics Data System (ADS)

    Koutserimpas, Theodoros T.; Alù, Andrea; Fleury, Romain

    2018-01-01

    Parity-time (PT )-symmetric wave devices, which exploit balanced interactions between material gain and loss, exhibit extraordinary properties, including lasing and flux-conserving scattering processes. In a seemingly different research field, periodically driven systems, also known as time-Floquet systems, have been widely studied as a relevant platform for reconfigurable active wave control and manipulation. In this article, we explore the connection between PT -symmetry and parametric time-Floquet systems. Instead of relying on material gain, we use parametric amplification by considering a time-periodic modulation of the refractive index at a frequency equal to twice the incident signal frequency. We show that the scattering from a simple parametric slab, whose dynamics follows the Mathieu equation, can be described by a PT -symmetric scattering matrix, whose PT -breaking threshold corresponds to the Mathieu instability threshold. By combining different parametric slabs modulated out of phase, we create PT -symmetric time-Floquet systems that feature exceptional scattering properties, such as coherent perfect absorption (CPA)-laser operation and bidirectional invisibility. These bidirectional properties, rare for regular PT -symmetric systems, are related to a compensation of parametric amplification due to multiple scattering between two parametric systems modulated with a phase difference.

  15. Parametric Modelling of As-Built Beam Framed Structure in Bim Environment

    NASA Astrophysics Data System (ADS)

    Yang, X.; Koehl, M.; Grussenmeyer, P.

    2017-02-01

    A complete documentation and conservation of a historic timber roof requires the integration of geometry modelling, attributional and dynamic information management and results of structural analysis. Recently developed as-built Building Information Modelling (BIM) technique has the potential to provide a uniform platform, which provides possibility to integrate the traditional geometry modelling, parametric elements management and structural analysis together. The main objective of the project presented in this paper is to develop a parametric modelling tool for a timber roof structure whose elements are leaning and crossing beam frame. Since Autodesk Revit, as the typical BIM software, provides the platform for parametric modelling and information management, an API plugin, able to automatically create the parametric beam elements and link them together with strict relationship, was developed. The plugin under development is introduced in the paper, which can obtain the parametric beam model via Autodesk Revit API from total station points and terrestrial laser scanning data. The results show the potential of automatizing the parametric modelling by interactive API development in BIM environment. It also integrates the separate data processing and different platforms into the uniform Revit software.

  16. Multi-parametric centrality method for graph network models

    NASA Astrophysics Data System (ADS)

    Ivanov, Sergei Evgenievich; Gorlushkina, Natalia Nikolaevna; Ivanova, Lubov Nikolaevna

    2018-04-01

    The graph model networks are investigated to determine centrality, weights and the significance of vertices. For centrality analysis appliesa typical method that includesany one of the properties of graph vertices. In graph theory, methods of analyzing centrality are used: in terms by degree, closeness, betweenness, radiality, eccentricity, page-rank, status, Katz and eigenvector. We have proposed a new method of multi-parametric centrality, which includes a number of basic properties of the network member. The mathematical model of multi-parametric centrality method is developed. Comparison of results for the presented method with the centrality methods is carried out. For evaluate the results for the multi-parametric centrality methodthe graph model with hundreds of vertices is analyzed. The comparative analysis showed the accuracy of presented method, includes simultaneously a number of basic properties of vertices.

  17. Reliable clarity automatic-evaluation method for optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Qin, Bangyong; Shang, Ren; Li, Shengyang; Hei, Baoqin; Liu, Zhiwen

    2015-10-01

    Image clarity, which reflects the sharpness degree at the edge of objects in images, is an important quality evaluate index for optical remote sensing images. Scholars at home and abroad have done a lot of work on estimation of image clarity. At present, common clarity-estimation methods for digital images mainly include frequency-domain function methods, statistical parametric methods, gradient function methods and edge acutance methods. Frequency-domain function method is an accurate clarity-measure approach. However, its calculation process is complicate and cannot be carried out automatically. Statistical parametric methods and gradient function methods are both sensitive to clarity of images, while their results are easy to be affected by the complex degree of images. Edge acutance method is an effective approach for clarity estimate, while it needs picking out the edges manually. Due to the limits in accuracy, consistent or automation, these existing methods are not applicable to quality evaluation of optical remote sensing images. In this article, a new clarity-evaluation method, which is based on the principle of edge acutance algorithm, is proposed. In the new method, edge detection algorithm and gradient search algorithm are adopted to automatically search the object edges in images. Moreover, The calculation algorithm for edge sharpness has been improved. The new method has been tested with several groups of optical remote sensing images. Compared with the existing automatic evaluation methods, the new method perform better both in accuracy and consistency. Thus, the new method is an effective clarity evaluation method for optical remote sensing images.

  18. Parametric approaches to micro-scale characterization of tissue volumes in vivo and ex vivo: Imaging microvasculature, attenuation, birefringence, and stiffness (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Sampson, David D.; Chin, Lixin; Gong, Peijun; Wijesinghe, Philip; Es'haghian, Shaghayegh; Allen, Wesley M.; Klyen, Blake R.; Kirk, Rodney W.; Kennedy, Brendan F.; McLaughlin, Robert A.

    2016-03-01

    INVITED TALK Advances in imaging tissue microstructure in living subjects, or in freshly excised tissue with minimum preparation and processing, are important for future diagnosis and surgical guidance in the clinical setting, particularly for application to cancer. Whilst microscopy methods continue to advance on the cellular scale and medical imaging is well established on the scale of the whole tumor or organ, it is attractive to consider imaging the tumor environment on the micro-scale, between that of cells and whole tissues. Such a scenario is ideally suited to optical coherence tomography (OCT), with the twin attractions of requiring little or no tissue preparation, and in vivo capability. OCT's intrinsic scattering contrast reveals many morphological features of tumors, but is frequently ineffective in revealing other important aspects, such as microvasculature, or in reliably distinguishing tumor from uninvolved stroma. To address these shortcomings, we are developing several advances on the basic OCT approach. We are exploring speckle fluctuations to image tissue microvasculature and we have been developing several parametric approaches to tissue micro-scale characterization. Our approaches extract, from a three-dimensional OCT data set, a two-dimensional image of an optical parameter, such as attenuation or birefringence, or a mechanical parameter, such as stiffness, that aids in characterizing the tissue. This latter method, termed optical coherence elastography, parallels developments in ultrasound and magnetic resonance imaging. Parametric imaging of birefringence and of stiffness both show promise in addressing the important issue of differentiating cancer from uninvolved stroma in breast tissue.

  19. Photon number amplification/duplication through parametric conversion

    NASA Technical Reports Server (NTRS)

    Dariano, G. M.; Macchiavello, C.; Paris, M.

    1993-01-01

    The performance of parametric conversion in achieving number amplification and duplication is analyzed. It is shown that the effective maximum gains G(sub *) remain well below their integer ideal values, even for large signals. Correspondingly, one has output Fano factors F(sub *) which are increasing functions of the input photon number. On the other hand, in the inverse (deamplifier/recombiner) operating mode quasi-ideal gains G(sub *) and small factors F(sub *) approximately equal to 10 percent are obtained. Output noise and non-ideal gains are ascribed to spontaneous parametric emission.

  20. Parametrically excited helicopter ground resonance dynamics with high blade asymmetries

    NASA Astrophysics Data System (ADS)

    Sanches, L.; Michon, G.; Berlioz, A.; Alazard, D.

    2012-07-01

    The present work is aimed at verifying the influence of high asymmetries in the variation of in-plane lead-lag stiffness of one blade on the ground resonance phenomenon in helicopters. The periodical equations of motions are analyzed by using Floquet's Theory (FM) and the boundaries of instabilities predicted. The stability chart obtained as a function of asymmetry parameters and rotor speed reveals a complex evolution of critical zones and the existence of bifurcation points at low rotor speed values. Additionally, it is known that when treated as parametric excitations; periodic terms may cause parametric resonances in dynamic systems, some of which can become unstable. Therefore, the helicopter is later considered as a parametrically excited system and the equations are treated analytically by applying the Method of Multiple Scales (MMS). A stability analysis is used to verify the existence of unstable parametric resonances with first and second-order sets of equations. The results are compared and validated with those obtained by Floquet's Theory. Moreover, an explanation is given for the presence of unstable motion at low rotor speeds due to parametric instabilities of the second order.

  1. Dense motion estimation using regularization constraints on local parametric models.

    PubMed

    Patras, Ioannis; Worring, Marcel; van den Boomgaard, Rein

    2004-11-01

    This paper presents a method for dense optical flow estimation in which the motion field within patches that result from an initial intensity segmentation is parametrized with models of different order. We propose a novel formulation which introduces regularization constraints between the model parameters of neighboring patches. In this way, we provide the additional constraints for very small patches and for patches whose intensity variation cannot sufficiently constrain the estimation of their motion parameters. In order to preserve motion discontinuities, we use robust functions as a regularization mean. We adopt a three-frame approach and control the balance between the backward and forward constraints by a real-valued direction field on which regularization constraints are applied. An iterative deterministic relaxation method is employed in order to solve the corresponding optimization problem. Experimental results show that the proposed method deals successfully with motions large in magnitude, motion discontinuities, and produces accurate piecewise-smooth motion fields.

  2. Ultrafast Coherent Dynamics of a Photonic Crystal All-Optical Switch.

    PubMed

    Colman, Pierre; Lunnemann, Per; Yu, Yi; Mørk, Jesper

    2016-12-02

    We present pump-probe measurements of an all-optical photonic crystal switch based on a nanocavity, resolving fast coherent temporal dynamics. The measurements demonstrate the importance of coherent effects typically neglected when considering nanocavity dynamics. In particular, we report the observation of an idler pulse and more than 10 dB parametric gain. The measurements are in good agreement with a theoretical model that ascribes the observation to oscillations of the free-carrier population in the nanocavity. The effect opens perspectives for the realization of new all-optical photonic crystal switches with unprecedented switching contrast.

  3. Parametric modelling of cost data in medical studies.

    PubMed

    Nixon, R M; Thompson, S G

    2004-04-30

    The cost of medical resources used is often recorded for each patient in clinical studies in order to inform decision-making. Although cost data are generally skewed to the right, interest is in making inferences about the population mean cost. Common methods for non-normal data, such as data transformation, assuming asymptotic normality of the sample mean or non-parametric bootstrapping, are not ideal. This paper describes possible parametric models for analysing cost data. Four example data sets are considered, which have different sample sizes and degrees of skewness. Normal, gamma, log-normal, and log-logistic distributions are fitted, together with three-parameter versions of the latter three distributions. Maximum likelihood estimates of the population mean are found; confidence intervals are derived by a parametric BC(a) bootstrap and checked by MCMC methods. Differences between model fits and inferences are explored.Skewed parametric distributions fit cost data better than the normal distribution, and should in principle be preferred for estimating the population mean cost. However for some data sets, we find that models that fit badly can give similar inferences to those that fit well. Conversely, particularly when sample sizes are not large, different parametric models that fit the data equally well can lead to substantially different inferences. We conclude that inferences are sensitive to choice of statistical model, which itself can remain uncertain unless there is enough data to model the tail of the distribution accurately. Investigating the sensitivity of conclusions to choice of model should thus be an essential component of analysing cost data in practice. Copyright 2004 John Wiley & Sons, Ltd.

  4. First-Order Parametric Model of Reflectance Spectra for Dyed Fabrics

    DTIC Science & Technology

    2016-02-19

    Unclassified Unlimited 31 Daniel Aiken (202) 279-5293 Parametric modeling Inverse /direct analysis This report describes a first-order parametric model of...Appendix: Dielectric Response Functions for Dyes Obtained by Inverse Analysis ……………………………...…………………………………………………….19 1 First-Order Parametric...which provides for both their inverse and direct modeling1. The dyes considered contain spectral features that are of interest to the U.S. Navy for

  5. Nonequilibrium Langevin approach to quantum optics in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Portolan, S.; di Stefano, O.; Savasta, S.; Rossi, F.; Girlanda, R.

    2008-01-01

    Recently, the possibility of generating nonclassical polariton states by means of parametric scattering has been demonstrated. Excitonic polaritons propagate in a complex interacting environment and contain real electronic excitations subject to scattering events and noise affecting quantum coherence and entanglement. Here, we present a general theoretical framework for the realistic investigation of polariton quantum correlations in the presence of coherent and incoherent interaction processes. The proposed theoretical approach is based on the nonequilibrium quantum Langevin approach for open systems applied to interacting-electron complexes described within the dynamics controlled truncation scheme. It provides an easy recipe to calculate multitime correlation functions which are key quantities in quantum optics. As a first application, we analyze the buildup of polariton parametric emission in semiconductor microcavities including the influence of noise originating from phonon-induced scattering.

  6. New graph polynomials in parametric QED Feynman integrals

    NASA Astrophysics Data System (ADS)

    Golz, Marcel

    2017-10-01

    In recent years enormous progress has been made in perturbative quantum field theory by applying methods of algebraic geometry to parametric Feynman integrals for scalar theories. The transition to gauge theories is complicated not only by the fact that their parametric integrand is much larger and more involved. It is, moreover, only implicitly given as the result of certain differential operators applied to the scalar integrand exp(-ΦΓ /ΨΓ) , where ΨΓ and ΦΓ are the Kirchhoff and Symanzik polynomials of the Feynman graph Γ. In the case of quantum electrodynamics we find that the full parametric integrand inherits a rich combinatorial structure from ΨΓ and ΦΓ. In the end, it can be expressed explicitly as a sum over products of new types of graph polynomials which have a combinatoric interpretation via simple cycle subgraphs of Γ.

  7. Parametrically driven scalar field in an expanding background

    NASA Astrophysics Data System (ADS)

    Yanez-Pagans, Sergio; Urzagasti, Deterlino; Oporto, Zui

    2017-10-01

    We study the existence and dynamic behavior of localized and extended structures in a massive scalar inflaton field ϕ in 1 +1 dimensions in the framework of an expanding universe with constant Hubble parameter. We introduce a parametric forcing, produced by another quantum scalar field ψ , over the effective mass squared around the minimum of the inflaton potential. For this purpose, we study the system in the context of the cubic quintic complex Ginzburg-Landau equation and find the associated amplitude equation to the cosmological scalar field equation, which near the parametric resonance allows us to find the field amplitude. We find homogeneous null solutions, flat-top expanding solitons, and dark soliton patterns. No persistent non-null solutions are found in the absence of parametric forcing, and divergent solutions are obtained when the forcing amplitude is greater than 4 /3 .

  8. Hyperpolarizability and Operational Magic Wavelength in an Optical Lattice Clock

    NASA Astrophysics Data System (ADS)

    Brown, R. C.; Phillips, N. B.; Beloy, K.; McGrew, W. F.; Schioppo, M.; Fasano, R. J.; Milani, G.; Zhang, X.; Hinkley, N.; Leopardi, H.; Yoon, T. H.; Nicolodi, D.; Fortier, T. M.; Ludlow, A. D.

    2017-12-01

    Optical clocks benefit from tight atomic confinement enabling extended interrogation times as well as Doppler- and recoil-free operation. However, these benefits come at the cost of frequency shifts that, if not properly controlled, may degrade clock accuracy. Numerous theoretical studies have predicted optical lattice clock frequency shifts that scale nonlinearly with trap depth. To experimentally observe and constrain these shifts in an 171Yb optical lattice clock, we construct a lattice enhancement cavity that exaggerates the light shifts. We observe an atomic temperature that is proportional to the optical trap depth, fundamentally altering the scaling of trap-induced light shifts and simplifying their parametrization. We identify an "operational" magic wavelength where frequency shifts are insensitive to changes in trap depth. These measurements and scaling analysis constitute an essential systematic characterization for clock operation at the 10-18 level and beyond.

  9. A unified framework for weighted parametric multiple test procedures.

    PubMed

    Xi, Dong; Glimm, Ekkehard; Maurer, Willi; Bretz, Frank

    2017-09-01

    We describe a general framework for weighted parametric multiple test procedures based on the closure principle. We utilize general weighting strategies that can reflect complex study objectives and include many procedures in the literature as special cases. The proposed weighted parametric tests bridge the gap between rejection rules using either adjusted significance levels or adjusted p-values. This connection is made by allowing intersection hypotheses of the underlying closed test procedure to be tested at level smaller than α. This may be also necessary to take certain study situations into account. For such cases we introduce a subclass of exact α-level parametric tests that satisfy the consonance property. When the correlation is known only for certain subsets of the test statistics, a new procedure is proposed to fully utilize this knowledge within each subset. We illustrate the proposed weighted parametric tests using a clinical trial example and conduct a simulation study to investigate its operating characteristics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Fitting C 2 Continuous Parametric Surfaces to Frontiers Delimiting Physiologic Structures

    PubMed Central

    Bayer, Jason D.

    2014-01-01

    We present a technique to fit C 2 continuous parametric surfaces to scattered geometric data points forming frontiers delimiting physiologic structures in segmented images. Such mathematical representation is interesting because it facilitates a large number of operations in modeling. While the fitting of C 2 continuous parametric curves to scattered geometric data points is quite trivial, the fitting of C 2 continuous parametric surfaces is not. The difficulty comes from the fact that each scattered data point should be assigned a unique parametric coordinate, and the fit is quite sensitive to their distribution on the parametric plane. We present a new approach where a polygonal (quadrilateral or triangular) surface is extracted from the segmented image. This surface is subsequently projected onto a parametric plane in a manner to ensure a one-to-one mapping. The resulting polygonal mesh is then regularized for area and edge length. Finally, from this point, surface fitting is relatively trivial. The novelty of our approach lies in the regularization of the polygonal mesh. Process performance is assessed with the reconstruction of a geometric model of mouse heart ventricles from a computerized tomography scan. Our results show an excellent reproduction of the geometric data with surfaces that are C 2 continuous. PMID:24782911

  11. Optimizing Nanoscale Quantitative Optical Imaging of Subfield Scattering Targets

    PubMed Central

    Henn, Mark-Alexander; Barnes, Bryan M.; Zhou, Hui; Sohn, Martin; Silver, Richard M.

    2016-01-01

    The full 3-D scattered field above finite sets of features has been shown to contain a continuum of spatial frequency information, and with novel optical microscopy techniques and electromagnetic modeling, deep-subwavelength geometrical parameters can be determined. Similarly, by using simulations, scattering geometries and experimental conditions can be established to tailor scattered fields that yield lower parametric uncertainties while decreasing the number of measurements and the area of such finite sets of features. Such optimized conditions are reported through quantitative optical imaging in 193 nm scatterfield microscopy using feature sets up to four times smaller in area than state-of-the-art critical dimension targets. PMID:27805660

  12. Free response approach in a parametric system

    NASA Astrophysics Data System (ADS)

    Huang, Dishan; Zhang, Yueyue; Shao, Hexi

    2017-07-01

    In this study, a new approach to predict the free response in a parametric system is investigated. It is proposed in the special form of a trigonometric series with an exponentially decaying function of time, based on the concept of frequency splitting. By applying harmonic balance, the parametric vibration equation is transformed into an infinite set of homogeneous linear equations, from which the principal oscillation frequency can be computed, and all coefficients of harmonic components can be obtained. With initial conditions, arbitrary constants in a general solution can be determined. To analyze the computational accuracy and consistency, an approach error function is defined, which is used to assess the computational error in the proposed approach and in the standard numerical approach based on the Runge-Kutta algorithm. Furthermore, an example of a dynamic model of airplane wing flutter on a turbine engine is given to illustrate the applicability of the proposed approach. Numerical solutions show that the proposed approach exhibits high accuracy in mathematical expression, and it is valuable for theoretical research and engineering applications of parametric systems.

  13. Design considerations for a servo optical projection system

    NASA Astrophysics Data System (ADS)

    Nadalsky, Michael; Allen, Daniel; Bien, Joseph

    1987-01-01

    The present servooptical projection system (SOPS) furnishes 'out-the-window' scenery for a pilot-training flight simulator; attention is given to the parametric tradeoffs made in the SOPS' optical design, as well as to its mechanical packaging and the servonetwork performance of the unit as integrated into a research/training helicopter flight simulator. The final SOPS configuration is a function of scan head design, assembly modularity, image deterioration method, and focal lengths and relative apertures.

  14. Integrated liquid-core optical fibers for ultra-efficient nonlinear liquid photonics.

    PubMed

    Kieu, K; Schneebeli, L; Norwood, R A; Peyghambarian, N

    2012-03-26

    We have developed a novel integrated platform for liquid photonics based on liquid core optical fiber (LCOF). The platform is created by fusion splicing liquid core optical fiber to standard single-mode optical fiber making it fully integrated and practical - a major challenge that has greatly hindered progress in liquid-photonic applications. As an example, we report here the realization of ultralow threshold Raman generation using an integrated CS₂ filled LCOF pumped with sub-nanosecond pulses at 532 nm and 1064 nm. The measured energy threshold for the Stokes generation is 1nJ, about three orders of magnitude lower than previously reported values in the literature for hydrogen gas, a popular Raman medium. The integrated LCOF platform opens up new possibilities for ultralow power nonlinear optics such as efficient white light generation for displays, mid-IR generation, slow light generation, parametric amplification, all-optical switching and wavelength conversion using liquids that have orders of magnitude larger optical nonlinearities compared with silica glass.

  15. Multi-copy entanglement purification with practical spontaneous parametric down conversion sources

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai-Shuai; Shu, Qi; Zhou, Lan; Sheng, Yu-Bo

    2017-06-01

    Entanglement purification is to distill the high quality entanglement from the low quality entanglement with local operations and classical communications. It is one of the key technologies in long-distance quantum communication. We discuss an entanglement purification protocol (EPP) with spontaneous parametric down conversion (SPDC) sources, in contrast to previous EPP with multi-copy mixed states, which requires ideal entanglement sources. We show that the SPDC source is not an obstacle for purification, but can benefit the fidelity of the purified mixed state. This EPP works for linear optics and is feasible in current experiment technology. Project supported by the National Natural Science Foundation of China (Grant Nos. 11474168 and 61401222), the Natural Science Foundation of Jiangsu Province, China (Grant No. BK20151502), the Qing Lan Project in Jiangsu Province, China, and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions, China.

  16. Comparison of parametric and bootstrap method in bioequivalence test.

    PubMed

    Ahn, Byung-Jin; Yim, Dong-Seok

    2009-10-01

    The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption.

  17. Comparison of Parametric and Bootstrap Method in Bioequivalence Test

    PubMed Central

    Ahn, Byung-Jin

    2009-01-01

    The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption. PMID:19915699

  18. Parametrization study of the land multiparameter VTI elastic waveform inversion

    NASA Astrophysics Data System (ADS)

    He, W.; Plessix, R.-É.; Singh, S.

    2018-06-01

    Multiparameter inversion of seismic data remains challenging due to the trade-off between the different elastic parameters and the non-uniqueness of the solution. The sensitivity of the seismic data to a given subsurface elastic parameter depends on the source and receiver ray/wave path orientations at the subsurface point. In a high-frequency approximation, this is commonly analysed through the study of the radiation patterns that indicate the sensitivity of each parameter versus the incoming (from the source) and outgoing (to the receiver) angles. In practice, this means that the inversion result becomes sensitive to the choice of parametrization, notably because the null-space of the inversion depends on this choice. We can use a least-overlapping parametrization that minimizes the overlaps between the radiation patterns, in this case each parameter is only sensitive in a restricted angle domain, or an overlapping parametrization that contains a parameter sensitive to all angles, in this case overlaps between the radiation parameters occur. Considering a multiparameter inversion in an elastic vertically transverse isotropic medium and a complex land geological setting, we show that the inversion with the least-overlapping parametrization gives less satisfactory results than with the overlapping parametrization. The difficulties come from the complex wave paths that make difficult to predict the areas of sensitivity of each parameter. This shows that the parametrization choice should not only be based on the radiation pattern analysis but also on the angular coverage at each subsurface point that depends on geology and the acquisition layout.

  19. Aircraft conceptual design - an adaptable parametric sizing methodology

    NASA Astrophysics Data System (ADS)

    Coleman, Gary John, Jr.

    Aerospace is a maturing industry with successful and refined baselines which work well for traditional baseline missions, markets and technologies. However, when new markets (space tourism) or new constrains (environmental) or new technologies (composite, natural laminar flow) emerge, the conventional solution is not necessarily best for the new situation. Which begs the question "how does a design team quickly screen and compare novel solutions to conventional solutions for new aerospace challenges?" The answer is rapid and flexible conceptual design Parametric Sizing. In the product design life-cycle, parametric sizing is the first step in screening the total vehicle in terms of mission, configuration and technology to quickly assess first order design and mission sensitivities. During this phase, various missions and technologies are assessed. During this phase, the designer is identifying design solutions of concepts and configurations to meet combinations of mission and technology. This research undertaking contributes the state-of-the-art in aircraft parametric sizing through (1) development of a dedicated conceptual design process and disciplinary methods library, (2) development of a novel and robust parametric sizing process based on 'best-practice' approaches found in the process and disciplinary methods library, and (3) application of the parametric sizing process to a variety of design missions (transonic, supersonic and hypersonic transports), different configurations (tail-aft, blended wing body, strut-braced wing, hypersonic blended bodies, etc.), and different technologies (composite, natural laminar flow, thrust vectored control, etc.), in order to demonstrate the robustness of the methodology and unearth first-order design sensitivities to current and future aerospace design problems. This research undertaking demonstrates the importance of this early design step in selecting the correct combination of mission, technologies and configuration to

  20. The parametric resonance—from LEGO Mindstorms to cold atoms

    NASA Astrophysics Data System (ADS)

    Kawalec, Tomasz; Sierant, Aleksandra

    2017-07-01

    We show an experimental setup based on a popular LEGO Mindstorms set, allowing us to both observe and investigate the parametric resonance phenomenon. The presented method is simple but covers a variety of student activities like embedded software development, conducting measurements, data collection and analysis. It may be used during science shows, as part of student projects and to illustrate the parametric resonance in mechanics or even quantum physics, during lectures or classes. The parametrically driven LEGO pendulum gains energy in a spectacular way, increasing its amplitude from 10° to about 100° within a few tens of seconds. We provide also a short description of a wireless absolute orientation sensor that may be used in quantitative analysis of driven or free pendulum movement.

  1. Manipulating and probing angular momentum and quantized circulation in optical fields and matter waves

    NASA Astrophysics Data System (ADS)

    Lowney, Joseph Daniel

    related to the statistical properties of turbulence in a superfluid. In the second part of this dissertation we explore frequency mixing, a subset of nonlinear optical processes in which one or more input optical beam(s) are converted into one or more output beams with different optical frequencies. The ability of parametric nonlinear processes such as second harmonic generation or parametric amplification to manipulate the OAM spectra of optical beams is an active area of research. In a theoretical and numerical investigation, two complimentary methods for sculpting the OAM spectra are developed. The first method employs second harmonic generation with two non-collinear input beams to develop a broad spectrum of OAM states in an optical field. The second method utilizes parametric amplification with collinear input beams to develop an OAM-dependent gain or attenuation, termed dichroism for OAM, to effectively narrow the OAM spectrum of an optical beam. The theoretical principles developed in this dissertation enhance our understanding of how nonlinear processes can be used to engineer the OAM spectra of optical beams and could serve as methods to increase the bandwidth of an optical signal by multiplexing over a range of OAM states.

  2. Free-form geometric modeling by integrating parametric and implicit PDEs.

    PubMed

    Du, Haixia; Qin, Hong

    2007-01-01

    Parametric PDE techniques, which use partial differential equations (PDEs) defined over a 2D or 3D parametric domain to model graphical objects and processes, can unify geometric attributes and functional constraints of the models. PDEs can also model implicit shapes defined by level sets of scalar intensity fields. In this paper, we present an approach that integrates parametric and implicit trivariate PDEs to define geometric solid models containing both geometric information and intensity distribution subject to flexible boundary conditions. The integrated formulation of second-order or fourth-order elliptic PDEs permits designers to manipulate PDE objects of complex geometry and/or arbitrary topology through direct sculpting and free-form modeling. We developed a PDE-based geometric modeling system for shape design and manipulation of PDE objects. The integration of implicit PDEs with parametric geometry offers more general and arbitrary shape blending and free-form modeling for objects with intensity attributes than pure geometric models.

  3. Parametric-Studies and Data-Plotting Modules for the SOAP

    NASA Technical Reports Server (NTRS)

    2008-01-01

    "Parametric Studies" and "Data Table Plot View" are the names of software modules in the Satellite Orbit Analysis Program (SOAP). Parametric Studies enables parameterization of as many as three satellite or ground-station attributes across a range of values and computes the average, minimum, and maximum of a specified metric, the revisit time, or 21 other functions at each point in the parameter space. This computation produces a one-, two-, or three-dimensional table of data representing statistical results across the parameter space. Inasmuch as the output of a parametric study in three dimensions can be a very large data set, visualization is a paramount means of discovering trends in the data (see figure). Data Table Plot View enables visualization of the data table created by Parametric Studies or by another data source: this module quickly generates a display of the data in the form of a rotatable three-dimensional-appearing plot, making it unnecessary to load the SOAP output data into a separate plotting program. The rotatable three-dimensionalappearing plot makes it easy to determine which points in the parameter space are most desirable. Both modules provide intuitive user interfaces for ease of use.

  4. Development of a Micro Pulsed Lidar and a Singly-Resonant Optical Parametric Oscillator for CO2 Dial for Use in Atmospheric Studies

    NASA Astrophysics Data System (ADS)

    Chantjaroen, Chat

    According to the Fifth Assessment Report (AR5) from the Intergovernmental Panel on Climate Change (IPCC), aerosols and CO2 are the largest contributors to anthropogenic radiative forcing--net negative for aerosols and positive for CO2. This relates to the amount of impact that aerosols and CO2 can have on our atmosphere and climate system. CO2 is the predominant greenhouse gas in the atmosphere and causes great impacts on our climate system. Recent studies show that a less well known atmospheric component--aerosols, which are solid particles or liquid droplets suspended in air, can cause great impact on our climate system too. They can affect our climate directly by absorbing and scattering sunlight to warm or cool our climate. They can also affect our climate indirectly by affecting cloud microphysical properties. Typically sulfate aerosols or sea salts act as condensation nuclei for clouds to form. Clouds are estimated to shade about 60% of the earth at any given time. They are preventing much of the sunlight from reaching the earth's surface and are helping with the flow of the global water cycle. These are what permit lifeforms on earth. In the IPCC report, both aerosols and CO2 also have the largest uncertainties and aerosols remains at a low level of scientific understanding. These indicate the need of more accurate measurements and that new technologies and instruments needs to be developed. This dissertation focuses on the development of two instruments--a scannable Micro-Pulsed Lidar (MPL) for atmospheric aerosol measurements and an Optical Parametric Oscillator (OPO) for use as a transmitter in a Differential Absorption Lidar (DIAL) for atmospheric CO2 measurements. The MPL demonstrates successful measurements of aerosols. It provides the total aerosol optical depth (AOD) and aerosol lidar ratio (Sa) that agree well with an instrument used by the Aerosol Robotic Network (AERONET). It also successfully provides range-resolved information about aerosols

  5. Parametric Equations: Push 'Em Back, Push 'Em Back, Way Back!

    ERIC Educational Resources Information Center

    Cieply, Joseph F.

    1993-01-01

    Stresses using the features of graphing calculators to teach parametric equations much earlier in the curriculum than is presently done. Examples using parametric equations to teach slopes and lines in beginning algebra, inverse functions in advanced algebra, the wrapping function, and simulations of physical phenomena are presented. (MAZ)

  6. Parametric Architecture in the Urban Space

    NASA Astrophysics Data System (ADS)

    Januszkiewicz, Krystyna; Kowalski, Karol G.

    2017-10-01

    The paper deals with the parametric architecture which is trying to introduce a new spatial language in the context for urban tissue that correspond to the artistic consciousness and the attitude of information and digital technologies era. The first part of the paper defines the main features of parametric architecture (such as: folding, continuity and curvilinearity) which are are characteristic of the new style of named the “parametricism”. This architecture is a strong emphasis on geometry, materiality, feasibility and sustainability, what emerges is an explicit agenda promoting material ornamentation, spatial spectacle and formal theatricality. The second part presents result of case study, especially parametric public use buildings, within the tissue of city. The analyzed objects are: The Sage Gateshead (1998-2004) in Gateshead, Kunsthaus in Graz (2000-2003), the Weltstadthaus (2003-2005) in Cologne, The Golden Terraces in Warsaw (2000-2007), the Metropol Parasol in Seville (2005-2011) the King Cross Station (2005-2012) in London, the headquarters of the Pathé Foundation (2006-2014) in Paris. Each of the enumerated examples shows a diverse approach to designing in the urban space, which reflect the age of digital technologies and the information society. In conclusion emphasizes, that new concept of the spatialization of architecture is the equivalent of the democratization of the political system, the liberalization of the economy, among other examples.

  7. Democratizing science with the aid of parametric design and additive manufacturing: Design and fabrication of a versatile and low-cost optical instrument for scattering measurement.

    PubMed

    Nadal-Serrano, Jose M; Nadal-Serrano, Adolfo; Lopez-Vallejo, Marisa

    2017-01-01

    This paper focuses on the application of rapid prototyping techniques using additive manufacturing in combination with parametric design to create low-cost, yet accurate and reliable instruments. The methodology followed makes it possible to make instruments with a degree of customization until now available only to a narrow audience, helping democratize science. The proposal discusses a holistic design-for-manufacturing approach that comprises advanced modeling techniques, open-source design strategies, and an optimization algorithm using free parametric software for both professional and educational purposes. The design and fabrication of an instrument for scattering measurement is used as a case of study to present the previous concepts.

  8. Democratizing science with the aid of parametric design and additive manufacturing: Design and fabrication of a versatile and low-cost optical instrument for scattering measurement

    PubMed Central

    Lopez-Vallejo, Marisa

    2017-01-01

    This paper focuses on the application of rapid prototyping techniques using additive manufacturing in combination with parametric design to create low-cost, yet accurate and reliable instruments. The methodology followed makes it possible to make instruments with a degree of customization until now available only to a narrow audience, helping democratize science. The proposal discusses a holistic design-for-manufacturing approach that comprises advanced modeling techniques, open-source design strategies, and an optimization algorithm using free parametric software for both professional and educational purposes. The design and fabrication of an instrument for scattering measurement is used as a case of study to present the previous concepts. PMID:29112987

  9. Josephson parametric converter saturation and higher order effects

    NASA Astrophysics Data System (ADS)

    Liu, G.; Chien, T.-C.; Cao, X.; Lanes, O.; Alpern, E.; Pekker, D.; Hatridge, M.

    2017-11-01

    Microwave parametric amplifiers based on Josephson junctions have become indispensable components of many quantum information experiments. One key limitation which has not been well predicted by theory is the gain saturation behavior which limits the amplifier's ability to process large amplitude signals. The typical explanation for this behavior in phase-preserving amplifiers based on three-wave mixing, such as the Josephson Parametric Converter, is pump depletion, in which the consumption of pump photons to produce amplification results in a reduction in gain. However, in this work, we present experimental data and theoretical calculations showing that the fourth-order Kerr nonlinearities inherent in Josephson junctions are the dominant factor. The Kerr-based theory has the unusual property of causing saturation to both lower and higher gains, depending on bias conditions. This work presents an efficient methodology for optimizing device performance in the presence of Kerr nonlinearities while retaining device tunability and points to the necessity of controlling higher-order Hamiltonian terms to make further improvements in parametric devices.

  10. Epicyclic helical channels for parametric resonance ionization cooling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Johson, Rolland Paul; Derbenev, Yaroslav

    Proposed next-generation muon colliders will require major technical advances to achieve rapid muon beam cooling requirements. Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. In PIC, a half-integer parametric resonance causes strong focusing of a muon beam at appropriately placed energy absorbers while ionization cooling limits the beam’s angular spread. Combining muon ionization cooling with parametric resonant dynamics in this way should then allow much smaller final transverse muon beam sizes than conventional ionization cooling alone. One of the PIC challenges is compensation of beam aberrations over a sufficiently wide parametermore » range while maintaining the dynamical stability with correlated behavior of the horizontal and vertical betatron motion and dispersion. We explore use of a coupling resonance to reduce the dimensionality of the problem and to shift the dynamics away from non-linear resonances. PIC simulations are presented.« less

  11. Harmonic generation and parametric decay in the ion cyclotron frequency range

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Skiff, F.N.; Wong, K.L.; Ono, M.

    1984-06-01

    Harmonic generation and parametric decay are examined in a toroidal ACT-I plasma using electrostatic plate antennas. The harmonic generation, which is consistent with sheath rectification, is sufficiently strong that the nonlinearly generated harmonic modes themselves decay parametrically. Resonant and nonresonant parametric decay of the second harmonic are observed and compared with uniform pump theory. Resonant decay of lower hybrid waves into lower hybrid waves and slow ion cyclotron waves is seen for the first time. Surprisingly, the decay processes are nonlinearly saturated, indicating absolute instability.

  12. Circulation and Directional Amplification in the Josephson Parametric Converter

    NASA Astrophysics Data System (ADS)

    Hatridge, Michael

    Nonreciprocal transport and directional amplification of weak microwave signals are fundamental ingredients in performing efficient measurements of quantum states of flying microwave light. This challenge has been partly met, as quantum-limited amplification is now regularly achieved with parametrically-driven, Josephson-junction based superconducting circuits. However, these devices are typically non-directional, requiring external circulators to separate incoming and outgoing signals. Recently this limitation has been overcome by several proposals and experimental realizations of both directional amplifiers and circulators based on interference between several parametric processes in a single device. This new class of multi-parametrically driven devices holds the promise of achieving a variety of desirable characteristics simultaneously- directionality, reduced gain-bandwidth constraints and quantum-limited added noise, and are good candidates for on-chip integration with other superconducting circuits such as qubits.

  13. Parametric models of reflectance spectra for dyed fabrics

    NASA Astrophysics Data System (ADS)

    Aiken, Daniel C.; Ramsey, Scott; Mayo, Troy; Lambrakos, Samuel G.; Peak, Joseph

    2016-05-01

    This study examines parametric modeling of NIR reflectivity spectra for dyed fabrics, which provides for both their inverse and direct modeling. The dye considered for prototype analysis is triarylamine dye. The fabrics considered are camouflage textiles characterized by color variations. The results of this study provide validation of the constructed parametric models, within reasonable error tolerances for practical applications, including NIR spectral characteristics in camouflage textiles, for purposes of simulating NIR spectra corresponding to various dye concentrations in host fabrics, and potentially to mixtures of dyes.

  14. Dispersion-Engineered Traveling Wave Kinetic Inductance Parametric Amplifier

    NASA Technical Reports Server (NTRS)

    Zmuidzinas, Jonas (Inventor); Day, Peter K. (Inventor)

    2014-01-01

    A traveling wave kinetic inductance parametric amplifier comprises a superconducting transmission line and a dispersion control element. The transmission line can include periodic variations of its dimension along its length. The superconducting material can include a high normal state resistivity material. In some instances the high normal state resistivity material includes nitrogen and a metal selected from the group consisting of titanium, niobium and vanadium. The traveling wave kinetic inductance parametric amplifier is expected to exhibit a noise temperature below 100 mK/GHz.

  15. Efficient model reduction of parametrized systems by matrix discrete empirical interpolation

    NASA Astrophysics Data System (ADS)

    Negri, Federico; Manzoni, Andrea; Amsallem, David

    2015-12-01

    In this work, we apply a Matrix version of the so-called Discrete Empirical Interpolation (MDEIM) for the efficient reduction of nonaffine parametrized systems arising from the discretization of linear partial differential equations. Dealing with affinely parametrized operators is crucial in order to enhance the online solution of reduced-order models (ROMs). However, in many cases such an affine decomposition is not readily available, and must be recovered through (often) intrusive procedures, such as the empirical interpolation method (EIM) and its discrete variant DEIM. In this paper we show that MDEIM represents a very efficient approach to deal with complex physical and geometrical parametrizations in a non-intrusive, efficient and purely algebraic way. We propose different strategies to combine MDEIM with a state approximation resulting either from a reduced basis greedy approach or Proper Orthogonal Decomposition. A posteriori error estimates accounting for the MDEIM error are also developed in the case of parametrized elliptic and parabolic equations. Finally, the capability of MDEIM to generate accurate and efficient ROMs is demonstrated on the solution of two computationally-intensive classes of problems occurring in engineering contexts, namely PDE-constrained shape optimization and parametrized coupled problems.

  16. Least Squares Approximation By G1 Piecewise Parametric Cubes

    DTIC Science & Technology

    1993-12-01

    ADDRESS(ES) 10.SPONSORING/MONITORING AGENCY REPORT NUMBER 11. SUPPLEMENTARY NOTES The views expressed in this thesis are those of the author and do not...CODE Approved for public release; distribution is unlimited. 13. ABSTRACT (maximum 200 words) Parametric piecewise cubic polynomials are used throughout...piecewise parametric cubic polynomial to a sequence of ordered points in the plane. Cubic Bdzier curves are used as a basis. The parameterization, the

  17. Infrared wavelength dependence of leaky mode losses and steady state distribution in W-type glass optical fibers

    NASA Astrophysics Data System (ADS)

    Djordjevich, Alexandar; Simović, Ana; Savović, Svetislav; Drljača, Branko

    2018-07-01

    Infrared wavelength dependence of leaky mode losses and steady state distribution (SSD) in W-type glass optical fibers (doubly clad fibers with three layers) is investigated in this paper for parametrically varied depths and widths of the fiber's intermediate optical layer. This enables a tailoring of configuration of the W-type fiber to suit an application at hand. We have shown that the proposed W-type fiber has better transmission characteristics at longer infrared wavelengths.

  18. Research on simplified parametric finite element model of automobile frontal crash

    NASA Astrophysics Data System (ADS)

    Wu, Linan; Zhang, Xin; Yang, Changhai

    2018-05-01

    The modeling method and key technologies of the automobile frontal crash simplified parametric finite element model is studied in this paper. By establishing the auto body topological structure, extracting and parameterizing the stiffness properties of substructures, choosing appropriate material models for substructures, the simplified parametric FE model of M6 car is built. The comparison of the results indicates that the simplified parametric FE model can accurately calculate the automobile crash responses and the deformation of the key substructures, and the simulation time is reduced from 6 hours to 2 minutes.

  19. Small-window parametric imaging based on information entropy for ultrasound tissue characterization

    PubMed Central

    Tsui, Po-Hsiang; Chen, Chin-Kuo; Kuo, Wen-Hung; Chang, King-Jen; Fang, Jui; Ma, Hsiang-Yang; Chou, Dean

    2017-01-01

    Constructing ultrasound statistical parametric images by using a sliding window is a widely adopted strategy for characterizing tissues. Deficiency in spatial resolution, the appearance of boundary artifacts, and the prerequisite data distribution limit the practicability of statistical parametric imaging. In this study, small-window entropy parametric imaging was proposed to overcome the above problems. Simulations and measurements of phantoms were executed to acquire backscattered radiofrequency (RF) signals, which were processed to explore the feasibility of small-window entropy imaging in detecting scatterer properties. To validate the ability of entropy imaging in tissue characterization, measurements of benign and malignant breast tumors were conducted (n = 63) to compare performances of conventional statistical parametric (based on Nakagami distribution) and entropy imaging by the receiver operating characteristic (ROC) curve analysis. The simulation and phantom results revealed that entropy images constructed using a small sliding window (side length = 1 pulse length) adequately describe changes in scatterer properties. The area under the ROC for using small-window entropy imaging to classify tumors was 0.89, which was higher than 0.79 obtained using statistical parametric imaging. In particular, boundary artifacts were largely suppressed in the proposed imaging technique. Entropy enables using a small window for implementing ultrasound parametric imaging. PMID:28106118

  20. Small-window parametric imaging based on information entropy for ultrasound tissue characterization

    NASA Astrophysics Data System (ADS)

    Tsui, Po-Hsiang; Chen, Chin-Kuo; Kuo, Wen-Hung; Chang, King-Jen; Fang, Jui; Ma, Hsiang-Yang; Chou, Dean

    2017-01-01

    Constructing ultrasound statistical parametric images by using a sliding window is a widely adopted strategy for characterizing tissues. Deficiency in spatial resolution, the appearance of boundary artifacts, and the prerequisite data distribution limit the practicability of statistical parametric imaging. In this study, small-window entropy parametric imaging was proposed to overcome the above problems. Simulations and measurements of phantoms were executed to acquire backscattered radiofrequency (RF) signals, which were processed to explore the feasibility of small-window entropy imaging in detecting scatterer properties. To validate the ability of entropy imaging in tissue characterization, measurements of benign and malignant breast tumors were conducted (n = 63) to compare performances of conventional statistical parametric (based on Nakagami distribution) and entropy imaging by the receiver operating characteristic (ROC) curve analysis. The simulation and phantom results revealed that entropy images constructed using a small sliding window (side length = 1 pulse length) adequately describe changes in scatterer properties. The area under the ROC for using small-window entropy imaging to classify tumors was 0.89, which was higher than 0.79 obtained using statistical parametric imaging. In particular, boundary artifacts were largely suppressed in the proposed imaging technique. Entropy enables using a small window for implementing ultrasound parametric imaging.

  1. Sparse-grid, reduced-basis Bayesian inversion: Nonaffine-parametric nonlinear equations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Peng, E-mail: peng@ices.utexas.edu; Schwab, Christoph, E-mail: christoph.schwab@sam.math.ethz.ch

    2016-07-01

    We extend the reduced basis (RB) accelerated Bayesian inversion methods for affine-parametric, linear operator equations which are considered in [16,17] to non-affine, nonlinear parametric operator equations. We generalize the analysis of sparsity of parametric forward solution maps in [20] and of Bayesian inversion in [48,49] to the fully discrete setting, including Petrov–Galerkin high-fidelity (“HiFi”) discretization of the forward maps. We develop adaptive, stochastic collocation based reduction methods for the efficient computation of reduced bases on the parametric solution manifold. The nonaffinity and nonlinearity with respect to (w.r.t.) the distributed, uncertain parameters and the unknown solution is collocated; specifically, by themore » so-called Empirical Interpolation Method (EIM). For the corresponding Bayesian inversion problems, computational efficiency is enhanced in two ways: first, expectations w.r.t. the posterior are computed by adaptive quadratures with dimension-independent convergence rates proposed in [49]; the present work generalizes [49] to account for the impact of the PG discretization in the forward maps on the convergence rates of the Quantities of Interest (QoI for short). Second, we propose to perform the Bayesian estimation only w.r.t. a parsimonious, RB approximation of the posterior density. Based on the approximation results in [49], the infinite-dimensional parametric, deterministic forward map and operator admit N-term RB and EIM approximations which converge at rates which depend only on the sparsity of the parametric forward map. In several numerical experiments, the proposed algorithms exhibit dimension-independent convergence rates which equal, at least, the currently known rate estimates for N-term approximation. We propose to accelerate Bayesian estimation by first offline construction of reduced basis surrogates of the Bayesian posterior density. The parsimonious surrogates can then be employed for online

  2. Optimization of two-photon wave function in parametric down conversion by adaptive optics control of the pump radiation.

    PubMed

    Minozzi, M; Bonora, S; Sergienko, A V; Vallone, G; Villoresi, P

    2013-02-15

    We present an efficient method for optimizing the spatial profile of entangled-photon wave function produced in a spontaneous parametric down conversion process. A deformable mirror that modifies a wavefront of a 404 nm CW diode laser pump interacting with a nonlinear β-barium borate type-I crystal effectively controls the profile of the joint biphoton function. The use of a feedback signal extracted from the biphoton coincidence rate is used to achieve the optimal wavefront shape. The optimization of the two-photon coupling into two, single spatial modes for correlated detection is used for a practical demonstration of this physical principle.

  3. Parametric Trace Slicing

    NASA Technical Reports Server (NTRS)

    Rosu, Grigore (Inventor); Chen, Feng (Inventor); Chen, Guo-fang; Wu, Yamei; Meredith, Patrick O. (Inventor)

    2014-01-01

    A program trace is obtained and events of the program trace are traversed. For each event identified in traversing the program trace, a trace slice of which the identified event is a part is identified based on the parameter instance of the identified event. For each trace slice of which the identified event is a part, the identified event is added to an end of a record of the trace slice. These parametric trace slices can be used in a variety of different manners, such as for monitoring, mining, and predicting.

  4. Parametric estimation for reinforced concrete relief shelter for Aceh cases

    NASA Astrophysics Data System (ADS)

    Atthaillah; Saputra, Eri; Iqbal, Muhammad

    2018-05-01

    This paper was a work in progress (WIP) to discover a rapid parametric framework for post-disaster permanent shelter’s materials estimation. The intended shelters were reinforced concrete construction with bricks as its wall. Inevitably, in post-disaster cases, design variations were needed to help suited victims condition. It seemed impossible to satisfy a beneficiary with a satisfactory design utilizing the conventional method. This study offered a parametric framework to overcome slow construction-materials estimation issue against design variations. Further, this work integrated parametric tool, which was Grasshopper to establish algorithms that simultaneously model, visualize, calculate and write the calculated data to a spreadsheet in a real-time. Some customized Grasshopper components were created using GHPython scripting for a more optimized algorithm. The result from this study was a partial framework that successfully performed modeling, visualization, calculation and writing the calculated data simultaneously. It meant design alterations did not escalate time needed for modeling, visualization, and material estimation. Further, the future development of the parametric framework will be made open source.

  5. Bounded Parametric Model Checking for Elementary Net Systems

    NASA Astrophysics Data System (ADS)

    Knapik, Michał; Szreter, Maciej; Penczek, Wojciech

    Bounded Model Checking (BMC) is an efficient verification method for reactive systems. BMC has been applied so far to verification of properties expressed in (timed) modal logics, but never to their parametric extensions. In this paper we show, for the first time that BMC can be extended to PRTECTL - a parametric extension of the existential version of CTL. To this aim we define a bounded semantics and a translation from PRTECTL to SAT. The implementation of the algorithm for Elementary Net Systems is presented, together with some experimental results.

  6. Parametric resonance in the early Universe—a fitting analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Figueroa, Daniel G.; Torrentí, Francisco, E-mail: daniel.figueroa@cern.ch, E-mail: f.torrenti@csic.es

    Particle production via parametric resonance in the early Universe, is a non-perturbative, non-linear and out-of-equilibrium phenomenon. Although it is a well studied topic, whenever a new scenario exhibits parametric resonance, a full re-analysis is normally required. To avoid this tedious task, many works present often only a simplified linear treatment of the problem. In order to surpass this circumstance in the future, we provide a fitting analysis of parametric resonance through all its relevant stages: initial linear growth, non-linear evolution, and relaxation towards equilibrium. Using lattice simulations in an expanding grid in 3+1 dimensions, we parametrize the dynamics' outcome scanningmore » over the relevant ingredients: role of the oscillatory field, particle coupling strength, initial conditions, and background expansion rate. We emphasize the inaccuracy of the linear calculation of the decay time of the oscillatory field, and propose a more appropriate definition of this scale based on the subsequent non-linear dynamics. We provide simple fits to the relevant time scales and particle energy fractions at each stage. Our fits can be applied to post-inflationary preheating scenarios, where the oscillatory field is the inflaton, or to spectator-field scenarios, where the oscillatory field can be e.g. a curvaton, or the Standard Model Higgs.« less

  7. flexsurv: A Platform for Parametric Survival Modeling in R

    PubMed Central

    Jackson, Christopher H.

    2018-01-01

    flexsurv is an R package for fully-parametric modeling of survival data. Any parametric time-to-event distribution may be fitted if the user supplies a probability density or hazard function, and ideally also their cumulative versions. Standard survival distributions are built in, including the three and four-parameter generalized gamma and F distributions. Any parameter of any distribution can be modeled as a linear or log-linear function of covariates. The package also includes the spline model of Royston and Parmar (2002), in which both baseline survival and covariate effects can be arbitrarily flexible parametric functions of time. The main model-fitting function, flexsurvreg, uses the familiar syntax of survreg from the standard survival package (Therneau 2016). Censoring or left-truncation are specified in ‘Surv’ objects. The models are fitted by maximizing the full log-likelihood, and estimates and confidence intervals for any function of the model parameters can be printed or plotted. flexsurv also provides functions for fitting and predicting from fully-parametric multi-state models, and connects with the mstate package (de Wreede, Fiocco, and Putter 2011). This article explains the methods and design principles of the package, giving several worked examples of its use. PMID:29593450

  8. Coupled parametric design of flow control and duct shape

    NASA Technical Reports Server (NTRS)

    Florea, Razvan (Inventor); Bertuccioli, Luca (Inventor)

    2009-01-01

    A method for designing gas turbine engine components using a coupled parametric analysis of part geometry and flow control is disclosed. Included are the steps of parametrically defining the geometry of the duct wall shape, parametrically defining one or more flow control actuators in the duct wall, measuring a plurality of performance parameters or metrics (e.g., flow characteristics) of the duct and comparing the results of the measurement with desired or target parameters, and selecting the optimal duct geometry and flow control for at least a portion of the duct, the selection process including evaluating the plurality of performance metrics in a pareto analysis. The use of this method in the design of inter-turbine transition ducts, serpentine ducts, inlets, diffusers, and similar components provides a design which reduces pressure losses and flow profile distortions.

  9. Supercritical nonlinear parametric dynamics of Timoshenko microbeams

    NASA Astrophysics Data System (ADS)

    Farokhi, Hamed; Ghayesh, Mergen H.

    2018-06-01

    The nonlinear supercritical parametric dynamics of a Timoshenko microbeam subject to an axial harmonic excitation force is examined theoretically, by means of different numerical techniques, and employing a high-dimensional analysis. The time-variant axial load is assumed to consist of a mean value along with harmonic fluctuations. In terms of modelling, a continuous expression for the elastic potential energy of the system is developed based on the modified couple stress theory, taking into account small-size effects; the kinetic energy of the system is also modelled as a continuous function of the displacement field. Hamilton's principle is employed to balance the energies and to obtain the continuous model of the system. Employing the Galerkin scheme along with an assumed-mode technique, the energy terms are reduced, yielding a second-order reduced-order model with finite number of degrees of freedom. A transformation is carried out to convert the second-order reduced-order model into a double-dimensional first order one. A bifurcation analysis is performed for the system in the absence of the axial load fluctuations. Moreover, a mean value for the axial load is selected in the supercritical range, and the principal parametric resonant response, due to the time-variant component of the axial load, is obtained - as opposed to transversely excited systems, for parametrically excited system (such as our problem here), the nonlinear resonance occurs in the vicinity of twice any natural frequency of the linear system; this is accomplished via use of the pseudo-arclength continuation technique, a direct time integration, an eigenvalue analysis, and the Floquet theory for stability. The natural frequencies of the system prior to and beyond buckling are also determined. Moreover, the effect of different system parameters on the nonlinear supercritical parametric dynamics of the system is analysed, with special consideration to the effect of the length-scale parameter.

  10. Full three-dimensional isotropic carpet cloak designed by quasi-conformal transformation optics.

    PubMed

    Silva, Daniely G; Teixeira, Poliane A; Gabrielli, Lucas H; Junqueira, Mateus A F C; Spadoti, Danilo H

    2017-09-18

    A fully three-dimensional carpet cloak presenting invisibility in all viewing angles is theoretically demonstrated. The design is developed using transformation optics and three-dimensional quasi-conformal mapping. Parametrization strategy and numerical optimization of the coordinate transformation deploying a quasi-Newton method is applied. A discussion about the minimum achievable anisotropy in the 3D transformation optics is presented. The method allows to reduce the anisotropy in the cloak and an isotropic medium could be considered. Numerical simulations confirm the strategy employed enabling the design of an isotropic reflectionless broadband carpet cloak independently of the incident light direction and polarization.

  11. Experimental implementation of a nonlinear beamsplitter based on a phase-sensitive parametric amplifier

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fang, Yami; Feng, Jingliang; Cao, Leiming

    2016-03-28

    Beamsplitters have played an important role in quantum optics experiments. They are often used to split and combine two beams, especially in the construct of an interferometer. In this letter, we experimentally implement a nonlinear beamsplitter using a phase-sensitive parametric amplifier, which is based on four-wave mixing in hot rubidium vapor. Here we show that, despite the different frequencies of the two input beams, the output ports of the nonlinear beamsplitter exhibit interference phenomena. We make measurements of the interference fringe visibility and study how various parameters, such as the intensity gain of the amplifier, the intensity ratio of themore » two input beams, and the one and two photon detunings, affect the behavior of the nonlinear beamsplitter. It may find potential applications in quantum metrology and quantum information processing.« less

  12. Analysis of Quantum Information Test-Bed by Parametric Down-Converted Photons Interference Measurement

    NASA Technical Reports Server (NTRS)

    To, Wing H.

    2005-01-01

    Quantum optical experiments require all the components involved to be extremely stable relative to each other. The stability can be "measured" by using an interferometric experiment. A pair of coherent photons produced by parametric down-conversion could be chosen to be orthogonally polarized initially. By rotating the polarization of one of the wave packets, they can be recombined at a beam splitter such that interference will occur. Theoretically, the interference will create four terms in the wave function. Two terms with both photons going to the same detector, and two terms will have the photons each going to different detectors. However, the latter will cancel each other out, thus no photons will arrive at the two detectors simultaneously under ideal conditions. The stability Of the test-bed can then be inferred by the dependence of coincidence count on the rotation angle.

  13. Performance of MgO:PPLN, KTA, and KNbO₃ for mid-wave infrared broadband parametric amplification at high average power.

    PubMed

    Baudisch, M; Hemmer, M; Pires, H; Biegert, J

    2014-10-15

    The performance of potassium niobate (KNbO₃), MgO-doped periodically poled lithium niobate (MgO:PPLN), and potassium titanyl arsenate (KTA) were experimentally compared for broadband mid-wave infrared parametric amplification at a high repetition rate. The seed pulses, with an energy of 6.5 μJ, were amplified using 410 μJ pump energy at 1064 nm to a maximum pulse energy of 28.9 μJ at 3 μm wavelength and at a 160 kHz repetition rate in MgO:PPLN while supporting a transform limited duration of 73 fs. The high average powers of the interacting beams used in this study revealed average power-induced processes that limit the scaling of optical parametric amplification in MgO:PPLN; the pump peak intensity was limited to 3.8  GW/cm² due to nonpermanent beam reshaping, whereas in KNbO₃ an absorption-induced temperature gradient in the crystal led to permanent internal distortions in the crystal structure when operated above a pump peak intensity of 14.4  GW/cm².

  14. Formation of parametric images using mixed-effects models: a feasibility study.

    PubMed

    Huang, Husan-Ming; Shih, Yi-Yu; Lin, Chieh

    2016-03-01

    Mixed-effects models have been widely used in the analysis of longitudinal data. By presenting the parameters as a combination of fixed effects and random effects, mixed-effects models incorporating both within- and between-subject variations are capable of improving parameter estimation. In this work, we demonstrate the feasibility of using a non-linear mixed-effects (NLME) approach for generating parametric images from medical imaging data of a single study. By assuming that all voxels in the image are independent, we used simulation and animal data to evaluate whether NLME can improve the voxel-wise parameter estimation. For testing purposes, intravoxel incoherent motion (IVIM) diffusion parameters including perfusion fraction, pseudo-diffusion coefficient and true diffusion coefficient were estimated using diffusion-weighted MR images and NLME through fitting the IVIM model. The conventional method of non-linear least squares (NLLS) was used as the standard approach for comparison of the resulted parametric images. In the simulated data, NLME provides more accurate and precise estimates of diffusion parameters compared with NLLS. Similarly, we found that NLME has the ability to improve the signal-to-noise ratio of parametric images obtained from rat brain data. These data have shown that it is feasible to apply NLME in parametric image generation, and the parametric image quality can be accordingly improved with the use of NLME. With the flexibility to be adapted to other models or modalities, NLME may become a useful tool to improve the parametric image quality in the future. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  15. Aberration compensation in a Skew parametric-resonance ionization cooling channel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sy, Amy V.; Derbenev, Yaroslav S.; Morozov, Vasiliy

    Skew Parametric-resonance Ionization Cooling (Skew PIC) represents a novel method for focusing of highly divergent particle beams, as in the final 6D cooling stage of a high-luminosity muon collider. In the muon collider concept, the resultant equilibrium transverse emittances from cooling with Skew PIC are an order of magnitude smaller than in conventional ionization cooling. The concept makes use of coupling of the transverse dynamic behavior, and the linear dynamics are well-behaved with good agreement between analytic solutions and simulation results. Compared to the uncoupled system, coupling of the transverse dynamic behavior purports to reduce the number of multipoles requiredmore » for aberration compensation while also avoiding unwanted resonances. Aberration compensation is more complicated in the coupled case, especially in the high-luminosity muon collider application where equilibrium angular spreads in the cooling channel are on the order of 200 mrad. We present recent progress on aberration compensation for control of highly divergent muon beams in the coupled correlated optics channel, and a simple cooling model to test the transverse acceptance of the channel.« less

  16. Open-Source 3D-Printable Optics Equipment

    PubMed Central

    Zhang, Chenlong; Anzalone, Nicholas C.; Faria, Rodrigo P.; Pearce, Joshua M.

    2013-01-01

    Just as the power of the open-source design paradigm has driven down the cost of software to the point that it is accessible to most people, the rise of open-source hardware is poised to drive down the cost of doing experimental science to expand access to everyone. To assist in this aim, this paper introduces a library of open-source 3-D-printable optics components. This library operates as a flexible, low-cost public-domain tool set for developing both research and teaching optics hardware. First, the use of parametric open-source designs using an open-source computer aided design package is described to customize the optics hardware for any application. Second, details are provided on the use of open-source 3-D printers (additive layer manufacturing) to fabricate the primary mechanical components, which are then combined to construct complex optics-related devices. Third, the use of the open-source electronics prototyping platform are illustrated as control for optical experimental apparatuses. This study demonstrates an open-source optical library, which significantly reduces the costs associated with much optical equipment, while also enabling relatively easily adapted customizable designs. The cost reductions in general are over 97%, with some components representing only 1% of the current commercial investment for optical products of similar function. The results of this study make its clear that this method of scientific hardware development enables a much broader audience to participate in optical experimentation both as research and teaching platforms than previous proprietary methods. PMID:23544104

  17. Open-source 3D-printable optics equipment.

    PubMed

    Zhang, Chenlong; Anzalone, Nicholas C; Faria, Rodrigo P; Pearce, Joshua M

    2013-01-01

    Just as the power of the open-source design paradigm has driven down the cost of software to the point that it is accessible to most people, the rise of open-source hardware is poised to drive down the cost of doing experimental science to expand access to everyone. To assist in this aim, this paper introduces a library of open-source 3-D-printable optics components. This library operates as a flexible, low-cost public-domain tool set for developing both research and teaching optics hardware. First, the use of parametric open-source designs using an open-source computer aided design package is described to customize the optics hardware for any application. Second, details are provided on the use of open-source 3-D printers (additive layer manufacturing) to fabricate the primary mechanical components, which are then combined to construct complex optics-related devices. Third, the use of the open-source electronics prototyping platform are illustrated as control for optical experimental apparatuses. This study demonstrates an open-source optical library, which significantly reduces the costs associated with much optical equipment, while also enabling relatively easily adapted customizable designs. The cost reductions in general are over 97%, with some components representing only 1% of the current commercial investment for optical products of similar function. The results of this study make its clear that this method of scientific hardware development enables a much broader audience to participate in optical experimentation both as research and teaching platforms than previous proprietary methods.

  18. Ince-Strutt stability charts for ship parametric roll resonance in irregular waves

    NASA Astrophysics Data System (ADS)

    Zhang, Xiao; Yang, He-zhen; Xiao, Fei; Xu, Pei-ji

    2017-08-01

    Ince-Strutt stability chart of ship parametric roll resonance in irregular waves is conducted and utilized for the exploration of the parametric roll resonance in irregular waves. Ship parametric roll resonance will lead to large amplitude roll motion and even wreck. Firstly, the equation describing the parametric roll resonance in irregular waves is derived according to Grim's effective theory and the corresponding Ince-Strutt stability charts are obtained. Secondly, the differences of stability charts for the parametric roll resonance in irregular and regular waves are compared. Thirdly, wave phases and peak periods are taken into consideration to obtain a more realistic sea condition. The influence of random wave phases should be taken into consideration when the analyzed points are located near the instability boundary. Stability charts for different wave peak periods are various. Stability charts are helpful for the parameter determination in design stage to better adapt to sailing condition. Last, ship variables are analyzed according to stability charts by a statistical approach. The increase of the metacentric height will help improve ship stability.

  19. Temperature Dependence of Parametric Phenomenon in Airborne Ultrasound for Temperature Measurement

    NASA Astrophysics Data System (ADS)

    Kon, Akihiko; Wakatsuki, Naoto; Mizutani, Koichi

    2008-08-01

    The temperature dependence of parametric phenomenon in air was experimentally studied. It was confirmed from experimental data that the amplitude of upper sideband sound with a frequency of 36.175 kHz, which is caused by parametric phenomenon between high-power ultrasound with a frequency of 20.175 kHz and another normal sound with a frequency of 16.0 kHz, is proportional to -0.88×10-4×(T+273.15). This temperature dependence of the amplitude of upper sideband sound caused by the parametric phenomenon suggests a simple and effective method of temperature measurement.

  20. Sgr A* Emission Parametrizations from GRMHD Simulations

    NASA Astrophysics Data System (ADS)

    Anantua, Richard; Ressler, Sean; Quataert, Eliot

    2018-06-01

    Galactic Center emission near the vicinity of the central black hole, Sagittarius (Sgr) A*, is modeled using parametrizations involving the electron temperature, which is found from general relativistic magnetohydrodynamic (GRMHD) simulations to be highest in the disk-outflow corona. Jet-motivated prescriptions generalizing equipartition of particle and magnetic energies, e.g., by scaling relativistic electron energy density to powers of the magnetic field strength, are also introduced. GRMHD jet (or outflow)/accretion disk/black hole (JAB) simulation postprocessing codes IBOTHROS and GRMONTY are employed in the calculation of images and spectra. Various parametric models reproduce spectral and morphological features, such as the sub-mm spectral bump in electron temperature models and asymmetric photon rings in equipartition-based models. The Event Horizon Telescope (EHT) will provide unprecedentedly high-resolution 230+ GHz observations of the "shadow" around Sgr A*'s supermassive black hole, which the synthetic models presented here will reverse-engineer. Both electron temperature and equipartition-based models can be constructed to be compatible with EHT size constraints for the emitting region of Sgr A*. This program sets the groundwork for devising a unified emission parametrization flexible enough to model disk, corona and outflow/jet regions with a small set of parameters including electron heating fraction and plasma beta.

  1. Design of optical mirror structures

    NASA Technical Reports Server (NTRS)

    Soosaar, K.

    1971-01-01

    The structural requirements for large optical telescope mirrors was studied with a particular emphasis placed on the three-meter Large Space Telescope primary mirror. Analysis approaches through finite element methods were evaluated with the testing and verification of a number of element types suitable for particular mirror loadings and configurations. The environmental conditions that a mirror will experience were defined and a candidate list of suitable mirror materials with their properties compiled. The relation of the mirror mechanical behavior to the optical performance is discussed and a number of suitable design criteria are proposed and implemented. A general outline of a systematic method to obtain the best structure for the three-meter diffraction-limited system is outlined. Finite element programs, using the STRUDL 2 analysis system, were written for specific mirror structures encompassing all types of active and passive mirror designs. Parametric studies on support locations, effects of shear deformation, diameter to thickness ratios, lightweight and sandwich mirror configurations, and thin shell active mirror needs were performed.

  2. Finding Rational Parametric Curves of Relative Degree One or Two

    ERIC Educational Resources Information Center

    Boyles, Dave

    2010-01-01

    A plane algebraic curve, the complete set of solutions to a polynomial equation: f(x, y) = 0, can in many cases be drawn using parametric equations: x = x(t), y = y(t). Using algebra, attempting to parametrize by means of rational functions of t, one discovers quickly that it is not the degree of f but the "relative degree," that describes how…

  3. Multi-parametric variational data assimilation for hydrological forecasting

    NASA Astrophysics Data System (ADS)

    Alvarado-Montero, R.; Schwanenberg, D.; Krahe, P.; Helmke, P.; Klein, B.

    2017-12-01

    Ensemble forecasting is increasingly applied in flow forecasting systems to provide users with a better understanding of forecast uncertainty and consequently to take better-informed decisions. A common practice in probabilistic streamflow forecasting is to force deterministic hydrological model with an ensemble of numerical weather predictions. This approach aims at the representation of meteorological uncertainty but neglects uncertainty of the hydrological model as well as its initial conditions. Complementary approaches use probabilistic data assimilation techniques to receive a variety of initial states or represent model uncertainty by model pools instead of single deterministic models. This paper introduces a novel approach that extends a variational data assimilation based on Moving Horizon Estimation to enable the assimilation of observations into multi-parametric model pools. It results in a probabilistic estimate of initial model states that takes into account the parametric model uncertainty in the data assimilation. The assimilation technique is applied to the uppermost area of River Main in Germany. We use different parametric pools, each of them with five parameter sets, to assimilate streamflow data, as well as remotely sensed data from the H-SAF project. We assess the impact of the assimilation in the lead time performance of perfect forecasts (i.e. observed data as forcing variables) as well as deterministic and probabilistic forecasts from ECMWF. The multi-parametric assimilation shows an improvement of up to 23% for CRPS performance and approximately 20% in Brier Skill Scores with respect to the deterministic approach. It also improves the skill of the forecast in terms of rank histogram and produces a narrower ensemble spread.

  4. A micromachined device describing over a hundred orders of parametric resonance

    NASA Astrophysics Data System (ADS)

    Jia, Yu; Du, Sijun; Arroyo, Emmanuelle; Seshia, Ashwin A.

    2018-04-01

    Parametric resonance in mechanical oscillators can onset from the periodic modulation of at least one of the system parameters, and the behaviour of the principal (1st order) parametric resonance has long been well established. However, the theoretically predicted higher orders of parametric resonance, in excess of the first few orders, have mostly been experimentally elusive due to the fast diminishing instability intervals. A recent paper experimentally reported up to 28 orders in a micromachined membrane oscillator. This paper reports the design and characterisation of a micromachined membrane oscillator with a segmented proof mass topology, in an attempt to amplify the inherent nonlinearities within the membrane layer. The resultant oscillator device exhibited up to over a hundred orders of parametric resonance, thus experimentally validating these ultra-high orders as well as overlapping instability transitions between these higher orders. This research introduces design possibilities for the transducer and dynamic communities, by exploiting the behaviour of these previously elusive higher order resonant regimes.

  5. Ranking Forestry Investments With Parametric Linear Programming

    Treesearch

    Paul A. Murphy

    1976-01-01

    Parametric linear programming is introduced as a technique for ranking forestry investments under multiple constraints; it combines the advantages of simple tanking and linear programming as capital budgeting tools.

  6. A Parametric Analysis of HELSTAR

    DTIC Science & Technology

    1983-12-01

    AFIT/GSO/OS/83D-7 S....A PARAMETRIC ANALYSIS OF HELSTAR THESIS James Miklasevich Captain, USAF AFIT/CSO/OS/83D-7 ’- 3 - Reproduced From J𔄁 04. • ’ S...1 Statement of Problem. ...... ................ ......... 3 Objectives of the Research. .... ............ . . . 3 ...Launch Scenarios ................. 39 Launch Sequencel................... 39 Launch Sequence 2 . . . . . .. . . . .. . . . . . 1 Launch Sequence 3

  7. Further Empirical Results on Parametric Versus Non-Parametric IRT Modeling of Likert-Type Personality Data

    ERIC Educational Resources Information Center

    Maydeu-Olivares, Albert

    2005-01-01

    Chernyshenko, Stark, Chan, Drasgow, and Williams (2001) investigated the fit of Samejima's logistic graded model and Levine's non-parametric MFS model to the scales of two personality questionnaires and found that the graded model did not fit well. We attribute the poor fit of the graded model to small amounts of multidimensionality present in…

  8. Range detection using entangled optical photons

    NASA Astrophysics Data System (ADS)

    Brandsema, Matthew J.; Narayanan, Ram M.; Lanzagorta, Marco

    2015-05-01

    Quantum radar is an emerging field that shows a lot of promise in providing significantly improved resolution compared to its classical radar counterpart. The key to this kind of resolution lies in the correlations created from the entanglement of the photons being used. Currently, the technology available only supports quantum radar implementation and validation in the optical regime, as opposed to the microwave regime, because microwave photons have very low energy compared to optical photons. Furthermore, there currently do not exist practical single photon detectors and generators in the microwave spectrum. Viable applications in the optical regime include deep sea target detection and high resolution detection in space. In this paper, we propose a conceptual architecture of a quantum radar which uses entangled optical photons based on Spontaneous Parametric Down Conversion (SPDC) methods. After the entangled photons are created and emerge from the crystal, the idler photon is detected very shortly thereafter. At the same time, the signal photon is sent out towards the target and upon its reflection will impinge on the detector of the radar. From these two measurements, correlation data processing is done to obtain the distance of the target away from the radar. Various simulations are then shown to display the resolution that is possible.

  9. Prepositioning emergency supplies under uncertainty: a parametric optimization method

    NASA Astrophysics Data System (ADS)

    Bai, Xuejie; Gao, Jinwu; Liu, Yankui

    2018-07-01

    Prepositioning of emergency supplies is an effective method for increasing preparedness for disasters and has received much attention in recent years. In this article, the prepositioning problem is studied by a robust parametric optimization method. The transportation cost, supply, demand and capacity are unknown prior to the extraordinary event, which are represented as fuzzy parameters with variable possibility distributions. The variable possibility distributions are obtained through the credibility critical value reduction method for type-2 fuzzy variables. The prepositioning problem is formulated as a fuzzy value-at-risk model to achieve a minimum total cost incurred in the whole process. The key difficulty in solving the proposed optimization model is to evaluate the quantile of the fuzzy function in the objective and the credibility in the constraints. The objective function and constraints can be turned into their equivalent parametric forms through chance constrained programming under the different confidence levels. Taking advantage of the structural characteristics of the equivalent optimization model, a parameter-based domain decomposition method is developed to divide the original optimization problem into six mixed-integer parametric submodels, which can be solved by standard optimization solvers. Finally, to explore the viability of the developed model and the solution approach, some computational experiments are performed on realistic scale case problems. The computational results reported in the numerical example show the credibility and superiority of the proposed parametric optimization method.

  10. Novel Semi-Parametric Algorithm for Interference-Immune Tunable Absorption Spectroscopy Gas Sensing

    PubMed Central

    Michelucci, Umberto; Venturini, Francesca

    2017-01-01

    One of the most common limits to gas sensor performance is the presence of unwanted interference fringes arising, for example, from multiple reflections between surfaces in the optical path. Additionally, since the amplitude and the frequency of these interferences depend on the distance and alignment of the optical elements, they are affected by temperature changes and mechanical disturbances, giving rise to a drift of the signal. In this work, we present a novel semi-parametric algorithm that allows the extraction of a signal, like the spectroscopic absorption line of a gas molecule, from a background containing arbitrary disturbances, without having to make any assumption on the functional form of these disturbances. The algorithm is applied first to simulated data and then to oxygen absorption measurements in the presence of strong fringes.To the best of the authors’ knowledge, the algorithm enables an unprecedented accuracy particularly if the fringes have a free spectral range and amplitude comparable to those of the signal to be detected. The described method presents the advantage of being based purely on post processing, and to be of extremely straightforward implementation if the functional form of the Fourier transform of the signal is known. Therefore, it has the potential to enable interference-immune absorption spectroscopy. Finally, its relevance goes beyond absorption spectroscopy for gas sensing, since it can be applied to any kind of spectroscopic data. PMID:28991161

  11. Single photons to multiple octaves: Engineering nonlinear optics in micro- and nano-structured media

    DTIC Science & Technology

    2017-05-18

    generation and amplification of ultrafast IR pulses. Both efforts took advantage of microstructured nonlinear media, e.g. quasi -phasematched (QPM...enhance the wave-mixing efficiency, especially for low-power devices. Because errors in fabrication of waveguides and quasi - phasematching gratings are... experimental demonstration of optical parametric chirped pulse amplifiers (OPCPA) in apodized aperiodic QPMgratings for high repetition rate, high

  12. Revisiting Parametric Types and Virtual Classes

    NASA Astrophysics Data System (ADS)

    Madsen, Anders Bach; Ernst, Erik

    This paper presents a conceptually oriented updated view on the relationship between parametric types and virtual classes. The traditional view is that parametric types excel at structurally oriented composition and decomposition, and virtual classes excel at specifying mutually recursive families of classes whose relationships are preserved in derived families. Conversely, while class families can be specified using a large number of F-bounded type parameters, this approach is complex and fragile; and it is difficult to use traditional virtual classes to specify object composition in a structural manner, because virtual classes are closely tied to nominal typing. This paper adds new insight about the dichotomy between these two approaches; it illustrates how virtual constraints and type refinements, as recently introduced in gbeta and Scala, enable structural treatment of virtual types; finally, it shows how a novel kind of dynamic type check can detect compatibility among entire families of classes.

  13. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHTI multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  14. Parametric Model of an Aerospike Rocket Engine

    NASA Technical Reports Server (NTRS)

    Korte, J. J.

    2000-01-01

    A suite of computer codes was assembled to simulate the performance of an aerospike engine and to generate the engine input for the Program to Optimize Simulated Trajectories. First an engine simulator module was developed that predicts the aerospike engine performance for a given mixture ratio, power level, thrust vectoring level, and altitude. This module was then used to rapidly generate the aerospike engine performance tables for axial thrust, normal thrust, pitching moment, and specific thrust. Parametric engine geometry was defined for use with the engine simulator module. The parametric model was also integrated into the iSIGHT multidisciplinary framework so that alternate designs could be determined. The computer codes were used to support in-house conceptual studies of reusable launch vehicle designs.

  15. Theoretical study of collinear optical frequency comb generation under multi-wave, transient stimulated Raman scattering in crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Smetanin, S N

    2014-11-30

    Using mathematical modelling we have studied the conditions of low-threshold collinear optical frequency comb generation under transient (picosecond) stimulated Raman scattering (SRS) and parametric four-wave coupling of SRS components in crystals. It is shown that Raman-parametric generation of an octave-spanning optical frequency comb occurs most effectively under intermediate, transient SRS at a pump pulse duration exceeding the dephasing time by five-to-twenty times. We have found the optimal values of not only the laser pump pulse duration, but also of the Raman crystal lengths corresponding to highly efficient generation of an optical frequency comb from the second anti-Stokes to the fourthmore » Stokes Raman components. For the KGd(WO{sub 4}){sub 2} (high dispersion) and Ba(NO{sub 3}){sub 2} (low dispersion) crystals pumped at a wavelength of 1.064 μm and a pulse duration five or more times greater than the dephasing time, the optimum length of the crystal was 0.3 and 0.6 cm, respectively, which is consistent with the condition of the most effective Stokes – anti-Stokes coupling ΔkL ≈ 15, where Δk is the wave detuning from phase matching of Stokes – anti-Stokes coupling, determined by the refractive index dispersion of the SRS medium. (nonlinear optical phenomena)« less

  16. Markovian Dynamics of Josephson Parametric Amplification

    NASA Astrophysics Data System (ADS)

    Kaiser, Waldemar; Haider, Michael; Russer, Johannes A.; Russer, Peter; Jirauschek, Christian

    2017-09-01

    In this work, we derive the dynamics of the lossy DC pumped non-degenerate Josephson parametric amplifier (DCPJPA). The main element in a DCPJPA is the superconducting Josephson junction. The DC bias generates the AC Josephson current varying the nonlinear inductance of the junction. By this way the Josephson junction acts as the pump oscillator as well as the time varying reactance of the parametric amplifier. In quantum-limited amplification, losses and noise have an increased impact on the characteristics of an amplifier. We outline the classical model of the lossy DCPJPA and derive the available noise power spectral densities. A classical treatment is not capable of including properties like spontaneous emission which is mandatory in case of amplification at the quantum limit. Thus, we derive a quantum mechanical model of the lossy DCPJPA. Thermal losses are modeled by the quantum Langevin approach, by coupling the quantized system to a photon heat bath in thermodynamic equilibrium. The mode occupation in the bath follows the Bose-Einstein statistics. Based on the second quantization formalism, we derive the Heisenberg equations of motion of both resonator modes. We assume the dynamics of the system to follow the Markovian approximation, i.e. the system only depends on its actual state and is memory-free. We explicitly compute the time evolution of the contributions to the signal mode energy and give numeric examples based on different damping and coupling constants. Our analytic results show, that this model is capable of including thermal noise into the description of the DC pumped non-degenerate Josephson parametric amplifier.

  17. Optical and magneto-optical properties of Co-doped CeO{sub 2−δ} films in the 0.5 to 4 eV range

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Veis, M., E-mail: veis@karlov.mff.cuni.cz; Kucera, M.; Zahradnik, M.

    2014-05-07

    Magnetically doped Ce{sub 1−x}Co{sub x}O{sub 2−δ} (nominal x = 0.05 and 0.10) films were systematically studied by spectroscopic ellipsometry and magneto-optical spectroscopy. The samples were prepared by pulsed laser deposition on MgO(100) substrates and grew as textured polycrystalline films with thickness between 200 and 750 nm. They exhibited room temperature ferromagnetism and an out-of-plane easy axis attributed to magnetoelastic effects from the in-plane compressive strain. The dispersion of dielectric function of Ce{sub 1−x}Co{sub x}O{sub 2−δ} films was parametrized by the sum of Tauc-Lorentz and damped Lorentz oscillators and adjusted numerically. Deduced optical band gaps were similar to those of pure CeO{sub 2}, butmore » the Co doping increased the optical absorption. The magneto-optical spectroscopy was carried out in both Faraday and Kerr configurations in the photon energy range from 0.5 to 4 eV, showing a strong dependence of the magneto-optical effect on the Co content near the optical band edge.« less

  18. A Semi-parametric Transformation Frailty Model for Semi-competing Risks Survival Data

    PubMed Central

    Jiang, Fei; Haneuse, Sebastien

    2016-01-01

    In the analysis of semi-competing risks data interest lies in estimation and inference with respect to a so-called non-terminal event, the observation of which is subject to a terminal event. Multi-state models are commonly used to analyse such data, with covariate effects on the transition/intensity functions typically specified via the Cox model and dependence between the non-terminal and terminal events specified, in part, by a unit-specific shared frailty term. To ensure identifiability, the frailties are typically assumed to arise from a parametric distribution, specifically a Gamma distribution with mean 1.0 and variance, say, σ2. When the frailty distribution is misspecified, however, the resulting estimator is not guaranteed to be consistent, with the extent of asymptotic bias depending on the discrepancy between the assumed and true frailty distributions. In this paper, we propose a novel class of transformation models for semi-competing risks analysis that permit the non-parametric specification of the frailty distribution. To ensure identifiability, the class restricts to parametric specifications of the transformation and the error distribution; the latter are flexible, however, and cover a broad range of possible specifications. We also derive the semi-parametric efficient score under the complete data setting and propose a non-parametric score imputation method to handle right censoring; consistency and asymptotic normality of the resulting estimators is derived and small-sample operating characteristics evaluated via simulation. Although the proposed semi-parametric transformation model and non-parametric score imputation method are motivated by the analysis of semi-competing risks data, they are broadly applicable to any analysis of multivariate time-to-event outcomes in which a unit-specific shared frailty is used to account for correlation. Finally, the proposed model and estimation procedures are applied to a study of hospital readmission among

  19. Parametrization of Drag and Turbulence for Urban Neighbourhoods with Trees

    NASA Astrophysics Data System (ADS)

    Krayenhoff, E. S.; Santiago, J.-L.; Martilli, A.; Christen, A.; Oke, T. R.

    2015-08-01

    Urban canopy parametrizations designed to be coupled with mesoscale models must predict the integrated effect of urban obstacles on the flow at each height in the canopy. To assess these neighbourhood-scale effects, results of microscale simulations may be horizontally-averaged. Obstacle-resolving computational fluid dynamics (CFD) simulations of neutrally-stratified flow through canopies of blocks (buildings) with varying distributions and densities of porous media (tree foliage) are conducted, and the spatially-averaged impacts on the flow of these building-tree combinations are assessed. The accuracy with which a one-dimensional (column) model with a one-equation (-) turbulence scheme represents spatially-averaged CFD results is evaluated. Individual physical mechanisms by which trees and buildings affect flow in the column model are evaluated in terms of relative importance. For the treed urban configurations considered, effects of buildings and trees may be considered independently. Building drag coefficients and length scale effects need not be altered due to the presence of tree foliage; therefore, parametrization of spatially-averaged flow through urban neighbourhoods with trees is greatly simplified. The new parametrization includes only source and sink terms significant for the prediction of spatially-averaged flow profiles: momentum drag due to buildings and trees (and the associated wake production of turbulent kinetic energy), modification of length scales by buildings, and enhanced dissipation of turbulent kinetic energy due to the small scale of tree foliage elements. Coefficients for the Santiago and Martilli (Boundary-Layer Meteorol 137: 417-439, 2010) parametrization of building drag coefficients and length scales are revised. Inclusion of foliage terms from the new parametrization in addition to the Santiago and Martilli building terms reduces root-mean-square difference (RMSD) of the column model streamwise velocity component and turbulent

  20. Parametric versus Cox's model: an illustrative analysis of divorce in Canada.

    PubMed

    Balakrishnan, T R; Rao, K V; Krotki, K J; Lapierre-adamcyk, E

    1988-06-01

    Recent demographic literature clearly recognizes the importance of survival modes in the analysis of cross-sectional event histories. Of the various survival models, Cox's (1972) partial parametric model has been very popular due to its simplicity, and readily available computer software for estimation, sometimes at the cost of precision and parsimony of the model. This paper focuses on parametric failure time models for event history analysis such as Weibell, lognormal, loglogistic, and exponential models. The authors also test the goodness of fit of these parametric models versus the Cox's proportional hazards model taking Kaplan-Meier estimate as base. As an illustration, the authors reanalyze the Canadian Fertility Survey data on 1st marriage dissolution with parametric models. Though these parametric model estimates were not very different from each other, there seemed to be a slightly better fit with loglogistic. When 8 covariates were used in the analysis, it was found that the coefficients were similar in the models, and the overall conclusions about the relative risks would not have been different. The findings reveal that in marriage dissolution, the differences according to demographic and socioeconomic characteristics may be far more important than is generally found in many studies. Therefore, one should not treat the population as homogeneous in analyzing survival probabilities of marriages, other than for cursory analysis of overall trends.