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Sample records for spontaneous four-wave mixing

  1. Spontaneous four-wave mixing in lossy microring resonators

    NASA Astrophysics Data System (ADS)

    Vernon, Z.; Sipe, J. E.

    2015-05-01

    We develop a general Hamiltonian treatment of spontaneous four-wave mixing in a microring resonator side-coupled to a channel waveguide. The effect of scattering losses in the ring is included, as well as parasitic nonlinear effects including self- and cross-phase modulation. A procedure for computing the output of such a system for arbitrary parameters and pump states is presented. For the limit of weak pumping an expression for the joint spectral intensity of generated photon pairs, as well as the singles-to-coincidences ratio, is derived.

  2. Correlated photon pair generation in AlGaAs nanowaveguides via spontaneous four-wave mixing.

    PubMed

    Kultavewuti, Pisek; Zhu, Eric Y; Qian, Li; Pusino, Vincenzo; Sorel, Marc; Stewart Aitchison, J

    2016-02-22

    We demonstrate a source of correlated photon pairs which will have applications in future integrated quantum photonic circuits. The source utilizes spontaneous four-wave mixing (SFWM) in a dispersion-engineered nanowaveguide made of AlGaAs, which has merits of negligible two-photon absorption and low spontaneous Raman scattering (SpRS). We observe a coincidence-to-accidental (CAR) ratio up to 177, mainly limited by propagation losses. Experimental results agree well with theoretical predictions of the SFWM photon pair generation and the SpRS noise photon generation. We also study the effects from the SpRS, propagation losses, and waveguide lengths on the quality of our source.

  3. Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing.

    PubMed

    Shi, Siyuan; Thomas, Abu; Corzo, Neil V; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

    2016-04-14

    Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors.

  4. Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing

    PubMed Central

    Shi, Siyuan; Thomas, Abu; Corzo, Neil V.; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

    2016-01-01

    Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors. PMID:27076032

  5. Broadband photon pair generation in green fluorescent proteins through spontaneous four-wave mixing

    NASA Astrophysics Data System (ADS)

    Shi, Siyuan; Thomas, Abu; Corzo, Neil V.; Kumar, Prem; Huang, Yuping; Lee, Kim Fook

    2016-04-01

    Recent studies in quantum biology suggest that quantum mechanics help us to explore quantum processes in biological system. Here, we demonstrate generation of photon pairs through spontaneous four-wave mixing process in naturally occurring fluorescent proteins. We develop a general empirical method for analyzing the relative strength of nonlinear optical interaction processes in five different organic fluorophores. Our results indicate that the generation of photon pairs in green fluorescent proteins is subject to less background noises than in other fluorophores, leading to a coincidence-to-accidental ratio ~145. As such proteins can be genetically engineered and fused to many biological cells, our experiment enables a new platform for quantum information processing in a biological environment such as biomimetic quantum networks and quantum sensors.

  6. Conversion efficiency in the process of copolarized spontaneous four-wave mixing

    SciTech Connect

    Garay-Palmett, Karina; U'Ren, Alfred B.; Rangel-Rojo, Raul

    2010-10-15

    We study the process of copolarized spontaneous four-wave mixing in single-mode optical fibers, with an emphasis on an analysis of the conversion efficiency. We consider both the monochromatic-pump and pulsed-pump regimes, as well as both the degenerate-pump and nondegenerate-pump configurations. We present analytical expressions for the conversion efficiency, which are given in terms of double integrals. In the case of pulsed pumps we take these expressions to closed analytical form with the help of certain approximations. We present results of numerical simulations, and compare them to values obtained from our analytical expressions, for the conversion efficiency as a function of several key experimental parameters.

  7. Exploitation of transverse spatial modes in spontaneous four wave mixing photon-pair sources

    NASA Astrophysics Data System (ADS)

    Cruz-Ramirez, Hector; Ramirez-Alarcon, Roberto; Cruz-Delgado, Daniel; Monroy-Ruz, Jorge; Ortiz-Ricardo, Erasto; Dominguez-Serna, Francisco; Garay-Palmett, Karina; U'Ren, Alfred B.

    2016-09-01

    We present a source for which multiple spontaneous four-wave mixing (SFWM) processes are supported in a few mode birefringent fiber, each process associated with a particular combination of transverse modes for the four participating waves. Within the weakly guiding regime, for which the propagation modes may be well approximated by linearly polarized (LP) modes, the departure from circular symmetry due to the fiber birefringence translates into orbital angular momentum (OAM) and parity conservation rules, i.e. reflecting elements from both azimuthal and rectangular symmetries. In our source: i) each process is group-velocity-matched so that it is, by design, nearly-factorable, and ii) the spectral separation between neighboring processes is greater than the marginal spectral width of each process. Consequently, there is a direct correspondence between the joint amplitude of each process and each of the Schmidt mode pairs of the overall two-photon state. The present paper covers work presented in Refs.1 and.2

  8. Heralded single-photon source from spontaneous four-wave mixing process in lossy waveguides

    NASA Astrophysics Data System (ADS)

    Silva, Nuno A.; Pinto, Armando N.

    2015-10-01

    We investigate theoretically the spontaneous four-wave mixing (FWM) process that occurs in optical waveguides, as a source of quantum correlated photon-pairs. We consider that the waveguide used to implement the spontaneous FWM process presents a high value of nonlinear parameter, γ = 93.4 W-1m-1, and a non-negligible value of loss coefficient, α = 133.3 dB/m. Moreover, the theoretical model also consider the Raman scattering that inevitably accompanies the FWM process, and generates time-uncorrelated (noise) photon pairs. We use the coincident-to-accidental ratio (CAR) as a figure of merit of the photon pair source, and we were able to observe a CAR of the order of 65 in a high loss regime. After, we use the time-correlated photon pairs generated by the spontaneous FWM process to implement a heralded single photon source at waveguide output. In this scenario, the detection of one photon of the pair heralds the presence of the other photon. The quality of the source was studied by the evaluation of the second order coherence function for one photon of the pair conditioned by the detection of its twin photon. We observe that the presence of a high loss coefficient tends to improve the quality of the photon source, when compared with the lossless regime, even considering the Raman noise photons. We obtain a value for the conditional second order coherence function of the order of 0.11 in absence of loss, and a value of 0.03 for a loss coefficient of 133.3 dB/m.

  9. Effects of noninstantaneous nonlinear processes on photon-pair generation by spontaneous four-wave mixing

    NASA Astrophysics Data System (ADS)

    Koefoed, Jacob G.; Christensen, Jesper B.; Rottwitt, Karsten

    2017-04-01

    We present a general model, based on a Hamiltonian approach, for the joint quantum state of photon pairs generated through pulsed spontaneous four-wave mixing, including nonlinear phase modulation and a finite material response time. For the case of a silica fiber, it is found that the pair-production rate depends weakly on the waveguide temperature, due to higher-order Raman scattering events, and more strongly on pump-pair frequency detuning. From the analytical model, a numerical scheme is derived, based on the well-known split-step method. This scheme allows computation of joint states where nontrivial effects are included, such as group-velocity dispersion and Raman scattering. In this work, the numerical model is used to study the impact of the noninstantaneous response on the prefiltering purity of heralded single photons. We find that for pump pulses shorter than 1 ps, a significant detuning-dependent change in quantum-mechanical purity may be observed in silica. This shows that Raman scattering not only introduces noise, but can also drastically change the spectral correlations in photon pairs when pumped with short pulses.

  10. Stimulated and spontaneous four-wave mixing in silicon-on-insulator coupled photonic wire nano-cavities

    NASA Astrophysics Data System (ADS)

    Azzini, Stefano; Grassani, Davide; Galli, Matteo; Gerace, Dario; Patrini, Maddalena; Liscidini, Marco; Velha, Philippe; Bajoni, Daniele

    2013-07-01

    We report on four-wave mixing in coupled photonic crystal nano-cavities on a silicon-on-insulator platform. Three photonic wire cavities are side-coupled to obtain three modes equally separated in energy. The structure is designed to be self-filtering, and we show that the pump is rejected by almost two orders of magnitude. We study both the stimulated and the spontaneous four-wave mixing processes: owing to the small modal volume, we find that signal and idler photons are generated with a hundred-fold increase in efficiency as compared to silicon micro-ring resonators.

  11. Photon pair-state preparation with tailored spectral properties by spontaneous four-wave mixing in photonic-crystal fiber.

    PubMed

    Garay-Palmett, K; McGuinness, H J; Cohen, Offir; Lundeen, J S; Rangel-Rojo, R; U'ren, A B; Raymer, M G; McKinstrie, C J; Radic, S; Walmsley, I A

    2007-10-29

    We study theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in photonic crystal optical fiber. We show that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications. We focus on the case exhibiting no spectral correlations in the two-photon component of the state, which we call factorability, and which allows heralding of single-photon pure-state wave packets without the need for spectral post filtering. We show that spontaneous four wave mixing exhibits a remarkable flexibility, permitting a wider class of two-photon states, including ultra-broadband, highly-anticorrelated states.

  12. Spontaneous four-wave mixing of de Broglie waves: beyond optics.

    PubMed

    Krachmalnicoff, V; Jaskula, J-C; Bonneau, M; Leung, V; Partridge, G B; Boiron, D; Westbrook, C I; Deuar, P; Ziń, P; Trippenbach, M; Kheruntsyan, K V

    2010-04-16

    We investigate the atom-optical analog of degenerate four-wave mixing by colliding two Bose-Einstein condensates of metastable helium. The momentum distribution of the scattered atoms is measured in three dimensions. A simple analogy with photon phase matching conditions suggests a spherical final distribution. We find, however, that it is an ellipsoid with radii smaller than the initial collision momenta. Numerical and analytical calculations agree with this and reveal the interplay between many-body effects, mean-field interaction, and the anisotropy of the source condensate.

  13. Waveguide Four-Wave Mixing

    DTIC Science & Technology

    1991-10-01

    PL-TR--91-1045 /’--"PL-TR-- AD-A243 555 91-1045 WAVEGUIDE FOUR -WAVE MIXING Thomas B. Simpson Jia-ming Liu JAYCOR San Diego, CA 92186-5154 October...Final Report; May 88 - Mar 91 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS WAVEGUIDE FOUR -WAVE MIXING C: F29601-88-C-0023 PE: 62601F PR: 3326 6. AUTHOR(S...for public release; distribution unlimited. 13. ABSTRACT (Maximum 200 words) This program has investigated four -wave mixing (4-win) in non- linear

  14. Parasitic nonlinearities in photon pair generation via integrated spontaneous four-wave mixing: Critical problem or distraction?

    NASA Astrophysics Data System (ADS)

    Helt, L. G.; Steel, M. J.; Sipe, J. E.

    2013-05-01

    We consider integrated photon pair sources based on spontaneous four-wave mixing and derive expressions for the pump powers at which various nonlinear processes become relevant for a variety of source materials and structures. These expressions serve as rules of thumb in identifying reasonable parameter regimes for the design of such sources. We demonstrate that if pump powers are kept low enough to suppress cross-phase modulation, multi-pair events as well as many other nonlinear effects are often also constrained to negligible levels.

  15. Photon-pair generation in lossy coupled-resonator optical waveguides via spontaneous four-wave mixing

    NASA Astrophysics Data System (ADS)

    Kamandar Dezfouli, Mohsen; Dignam, Marc M.

    2017-03-01

    We theoretically model pair generation and evolution via the nonlinear process of spontaneous four-wave mixing in a coupled-resonator optical waveguide in a photonic crystal slab. Using the adjoint master equation for a system of lossy coupled cavities, we calculate a symmetrized second-order coherence function to determine pair detection probability. We find that the scattering loss can have as large an effect on pair generation as waveguide dispersion. In particular, the wave-vector dependence of the loss can shift the frequency of the maximum detection probability and therefore cannot, in general, be ignored or treated via a simple overall loss factor.

  16. Double-heralded generation of two-photon-states by spontaneous four-wave-mixing in the presence of noise.

    PubMed

    Smith, Roger A; Reddy, Dileep V; Vitullo, Dashiell L P; Raymer, M G

    2016-03-21

    We present an experimental method for creating and verifying photon-number states created by non-degenerate, third-order nonlinear-optical photon-pair sources. By using spatially multiplexed, thresholding single-photon detectors and inverting a conditional probability matrix, we determine the photon-number probabilities created through heralded spontaneous four-wave-mixing. The deleterious effects of noise photons on reliable heralding are investigated and shown to degrade the conditional preparation of two-photon number states more than they degrade conditional single-photon states. We derive the equivalence between the presence of unwanted noise in the herald channel and loss in the signal channel of heralded experiments. A procedure for characterizing the noise-photon contributions, and a means of estimating the herald noise-free photon-number distribution is demonstrated.

  17. Photon-pair generation by intermodal spontaneous four-wave mixing in birefringent, weakly guiding optical fibers

    NASA Astrophysics Data System (ADS)

    Garay-Palmett, K.; Cruz-Delgado, D.; Dominguez-Serna, F.; Ortiz-Ricardo, E.; Monroy-Ruz, J.; Cruz-Ramirez, H.; Ramirez-Alarcon, R.; U'Ren, A. B.

    2016-03-01

    We present a theoretical and experimental study of the generation of photon pairs through the process of spontaneous four-wave mixing (SFWM) in a few-mode, birefringent fiber. Under these conditions, multiple SFWM processes are in fact possible, each associated with a different combination of transverse modes for the four waves involved. We show that in the weakly guiding regime, for which the propagation modes may be well approximated by linearly polarized modes, the departure from circular symmetry due to the fiber birefringence translates into conservation rules, which retain elements from azimuthal and rectangular symmetries: both OAM and parity must be conserved for a process to be viable. We have implemented a SFWM source based on a bowtie birefringent fiber, and have measured for a collection of pump wavelengths the SFWM spectra of each of the signal and idler photons in coincidence with its partner photon. We have used this information, together with knowledge of the transverse modes into which the signal and idler photons are emitted, as input for a genetic algorithm, which accomplishes two tasks: (i) the identification of the particular SFWM processes that are present in the source, and (ii) the characterization of the fiber used.

  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. Generation of polarization-entangled photon pairs and violation of Bell's inequality using spontaneous four-wave mixing in a fiber loop

    SciTech Connect

    Takesue, Hiroki; Inoue, Kyo

    2004-09-01

    We report the generation of polarization entangled photon pairs in the 1550-nm wavelength band using spontaneous four-wave mixing in a dispersion-shifted fiber loop. The use of the fiber-loop configuration made it possible to generate polarization entangled states very stably. With accidental coincidences subtracted, we obtained coincidence fringes with >90% visibilities, and observed a violation of Bell's inequality by seven standard deviations. We also confirmed the preservation of the quantum correlation between the photons even after they had been separated by 20 km of optical fiber.

  20. Four-Wave Mixing in Alexandrite Crystals,

    DTIC Science & Technology

    Degenerate four-wave mixing was observed in alexandrite crystals (BeAl2O4:Cr3+), and the signal beam efficiency and decay rate were measured as...the crystal. Originator- supplied keywords include: Lasers, Alexandrite , Non-Linear Optics.

  1. Spectral tunability of two-photon states generated by spontaneous four-wave mixing: fibre tapering, temperature variation and longitudinal stress

    NASA Astrophysics Data System (ADS)

    Ortiz-Ricardo, E.; Bertoni-Ocampo, C.; Ibarra-Borja, Z.; Ramirez-Alarcon, R.; Cruz-Delgado, D.; Cruz-Ramirez, H.; Garay-Palmett, K.; U'Ren, A. B.

    2017-09-01

    We explore three different mechanisms designed to controllably tune the joint spectrum of photon pairs produced by the spontaneous four-wave mixing (SFWM) process in optical fibres. The first of these is fibre tapering, which exploits the modified optical dispersion resulting from reducing the core radius. We have presented a theory of SFWM for tapered fibres, as well as experimental results for the SFWM coincidence spectra as a function of the reduction in core radius due to tapering. The other two techniques that we have explored are temperature variation and application of longitudinal stress. While the maximum spectral shift observed with these two techniques is smaller than for fibre tapering, they are considerably simpler to implement and have the important advantage that they are based on the use of a single, suitably controlled, fibre specimen.

  2. Diffraction manipulation by four-wave mixing.

    PubMed

    Katzir, Itay; Ron, Amiram; Firstenberg, Ofer

    2015-03-09

    We suggest a scheme to manipulate paraxial diffraction by utilizing the dependency of a four-wave mixing process on the relative angle between the light fields. A microscopic model for four-wave mixing in a Λ-type level structure is introduced and compared to recent experimental data. We show that images with feature size as low as 10 μm can propagate with very little or even negative diffraction. The mechanism is completely different from that conserving the shape of spatial solitons in nonlinear media, as here diffraction is suppressed for arbitrary spatial profiles. At the same time, the gain inherent to the nonlinear process prevents loss and allows for operating at high optical depths. Our scheme does not rely on atomic motion and is thus applicable to both gaseous and solid media.

  3. Four-wave-mixing gap solitons

    SciTech Connect

    Zhang Yanpeng; Wang Zhiguo; Zheng Huaibin; Yuan Chenzhi; Li Changbiao; Lu Keqing; Xiao Min

    2010-11-15

    We report an experimental demonstration of generating gap soliton trains in a four-wave-mixing (FWM) signal. Such spatial FWM surfacelike gap soliton trains are induced in a periodically modulated self-defocusing atomic medium by the cross-phase modulation, which can be reshaped under different experimental conditions, such as different atomic densities, nonlinear dispersions, and dressing fields. Controlling spatial gap solitons can have important applications in image memory, processing, and communication.

  4. Four-wave mixing in alexandrite crystals

    NASA Astrophysics Data System (ADS)

    Ghazzawi, Ali M.; Tyminski, Jacek K.; Powell, Richard C.; Walling, John C.

    1984-12-01

    Degenerate four-wave mixing was observed in alexandrite crystals (BeAl2O4: Cr3+), and the signal beam efficiency and decay rate were measured as functions of pump beam-crossing angle, wavelength, and power. The results are consistent with scattering from excited-state population gratings related to the difference in dispersion of the Cr3+ ions in the ground and metastable states. These gratings can be selectively established with Cr3+ ions in the inversion or mirror sites depending on the excitation wavelength. Strong scattering occurs only for pump beams polarized parallel to the b direction of the crystal.

  5. Resonantly enhanced four-wave mixing

    DOEpatents

    Begley, Richard F.; Kurnit, Norman A.

    1978-01-01

    A method and apparatus for achieving large susceptibilities and long interaction lengths in the generation of new wavelengths in the infrared spectral region. A process of resonantly enhanced four-wave mixing is employed, utilizing existing laser sources, such as the CO.sub.2 laser, to irradiate a gaseous media. The gaseous media, comprising NH.sub.3, CH.sub.3 F, D.sub.2, HCl, HF, CO, and H.sub.2 or some combination thereof, are of particular interest since they are capable of providing high repetition rate operation at high flux densities where crystal damage problems become a limitation.

  6. Effect of chromatic-dispersion-induced chirp on the temporal coherence properties of individual beams from spontaneous four-wave mixing

    SciTech Connect

    Ma Xiaoxin; Li Xiaoying; Cui Liang; Guo Xueshi; Yang Lei

    2011-08-15

    Temporal coherence of individual signal or idler beam, determined by the spectral correlation property of photon pairs, is important for realizing quantum interference among independent sources. Based on spontaneous four-wave mixing in optical fibers, we study the effect of chirp on the temporal coherence property by introducing a different amount of chirp into either the pulsed pump or individual signal (idler) beam. The investigation shows that the pump chirp induces additional frequency correlation into photon pairs; the mutual spectral correlation of photon pairs and the coherence of individual beam can be characterized by measuring the intensity correlation function g{sup (2)} of the individual beam. To improve the coherence degree, the pump chirp should be minimized. Moreover, a Hong-Ou-Mandel-type two-photon interference experiment with the signal beams generated in two different fibers illustrates that the chirp of the individual signal (idler) beam does not change the temporal coherence degree, but affects the temporal mode matching. To achieve high visibility among multiple sources, apart from improving the coherence degree, mode matching should be optimized by managing the chirps of individual beams.

  7. Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing

    NASA Astrophysics Data System (ADS)

    Sun, Yu-Ping; Liu, Ji-Cai; Wang, Chuan-Kui; Gel'Mukhanov, Faris

    2010-01-01

    We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p3/2-4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p3/2 and 3s-2p3/2, which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p3/2. The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

  8. Quantum dynamics of Kerr optical frequency combs below and above threshold: Spontaneous four-wave mixing, entanglement, and squeezed states of light

    NASA Astrophysics Data System (ADS)

    Chembo, Yanne K.

    2016-03-01

    The dynamical behavior of Kerr optical frequency combs is very well understood today from the perspective of the semiclassical approximation. These combs are obtained by pumping an ultrahigh-Q whispering-gallery mode resonator with a continuous-wave laser. The long-lifetime photons are trapped within the toruslike eigenmodes of the resonator, where they interact nonlinearly via the Kerr effect. In this article, we use quantum Langevin equations to provide a theoretical understanding of the nonclassical behavior of these combs when pumped below and above threshold. In the configuration where the system is under threshold, the pump field is the unique oscillating mode inside the resonator, and it triggers the phenomenon of spontaneous four-wave mixing, where two photons from the pump are symmetrically up- and down-converted in the Fourier domain. This phenomenon, also referred to as parametric fluorescence, can only be understood and analyzed from a fully quantum perspective as a consequence of the coupling between the field of the central (pumped) mode and the vacuum fluctuations of the various side modes. We analytically calculate the power spectra of the spontaneous emission noise, and we show that these spectra can be either single- or double-peaked depending on the value of the laser frequency, chromatic dispersion, pump power, and spectral distance between the central mode and the side mode of interest. We also calculate as well the overall spontaneous noise power per side mode and propose simplified analytical expressions for some particular cases. In the configuration where the system is pumped above threshold, we investigate the phenomena of quantum correlations and multimode squeezed states of light that can occur in the Kerr frequency combs originating from stimulated four-wave mixing. We show that for all stationary spatiotemporal patterns, the side modes that are symmetrical relative to the pumped mode in the frequency domain display quantum correlations

  9. Geometric interpretation of four-wave mixing

    NASA Astrophysics Data System (ADS)

    Ott, J. R.; Steffensen, H.; Rottwitt, K.; McKinstrie, C. J.

    2013-10-01

    The nonlinear phenomenon of four-wave mixing (FWM) is investigated using a method, where, without the need of calculus, both phase and amplitudes of the mixing fields are visualized simultaneously, giving a complete overview of the FWM dynamics. This is done by introducing a set of Stokes-like coordinates of the electric fields, which reduce the FWM dynamics to a closed two-dimensional surface, similar to the Bloch sphere of quantum electrodynamics or the Pointcaré sphere in polarization dynamics. The coordinates are chosen so as to use the gauge invariance symmetries of the FWM equations which also give the conservation of action flux known as the Manley-Rowe relations. This reduces the dynamics of FWM to the one-dimensional intersection between the closed two-dimensional surface and the phase-plane given by the conserved Hamiltonian. The analysis is advantageous for visualizing phase-dependent FWM phenomena which are found in a large variety of nonlinear systems and even in various optical communication schemes.

  10. Signal Processing with Degenrate Four-Wave Mixing.

    DTIC Science & Technology

    1987-03-17

    which mann geometry, the four -wave mixing signal observed limits the process to pulses of 100 ps or less. Note also was due to heating of the metal film... four -wave mixing to produced grating. With pulses 28 ps long. 0.6 ns decay real-time processing is time reversal of an optical wave- times were...34’Continuous backward-wave generation by degenerate four -wave the heating effects which dominated their experiment.miigiopca bes--prLt.-vl. 4p .4--419

  11. Quantum Image Processing and Storage with Four Wave Mixing

    DTIC Science & Technology

    2016-08-10

    use of four-wave mixing (4WM) in atomic vapors. image processing, nonlinear optics, optical memory, quantum optics U U U UU INSTRUCTIONS FOR...the use of four-wave mixing (4WM) in atomic vapors. We have worked to study the propagation of quantum correlations, improve low- frequency squeezing...light near a Rb atomic resonance that has proven to be fairly easy to implement and robust to operate, and has been adopted by a number of groups

  12. Polarization switch of four-wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-02-15

    Degenerate spontaneous four-wave mixing is considered in a large mode area hybrid photonic crystal fiber. Numerical and experimental results show birefringence assisted four-wave mixing for a certain polarization state of the pump field. The parametric gain can be turned on and off by switching the polarization state of the pump field between the two principal axis of the hybrid photonic crystal fiber.

  13. Signal enhancement in collinear four-wave mixing

    SciTech Connect

    McKinstrie, C.J.; Luther, G.G.; Batha, S. )

    1990-03-01

    The solitary-wave solutions of the four-wave equations are studied, and their relevance to four-wave mixing in finite media is discussed. In general, the transfer of action from the pump waves to the probe and signal waves is limited by nonlinear phase shifts that detune the interaction. However, by controlling the linear phase mismatch judiciously, it is often possible to effect a complete transfer of action from the pump waves to the probe and signal waves.

  14. Four-wave-mixing suppression in Er 3+-fiber amplifiers by backward pumping

    NASA Astrophysics Data System (ADS)

    Adel, P.; Engelbrecht, M.; Wandt, D.; Fallnich, C.

    2007-03-01

    Amplification of chirped fs-pulses in an Erbium doped fiber amplifier upto 0.8 μJ resulted in an additional peak in the spectrum at 1584 nm. This peak, attributable to four-wave-mixing between the signal centered at 1559 nm and amplified spontaneous emission at 1534 nm, hinders the temporal recompression of the amplified chirped pulse. Compared to the forward pumping configuration, this four-wave-mixing in the amplifier was largely reduced in a backward pumping configuration. Based on simulations, explanations for the observed influence of the pump direction on the four-wave-mixing efficiency are presented. The results pointed out that the gain spectrum distribution along the fiber strongly influences four-wave-mixing effects in fiber amplifiers even for constant overall gain spectrum.

  15. Intermodal and cross-polarization four-wave mixing in large-core hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Olausson, Christina B; Lægsgaard, Jesper

    2015-03-09

    Degenerate four-wave mixing is considered in large mode area hybrid photonic crystal fibers, combining photonic bandgap guidance and index guidance. Co- and orthogonally polarized pump, signal and idler fields are considered numerically by calculating the parametric gain and experimentally by spontaneous degenerate four-wave mixing. Intermodal and birefringence assisted intramodal phase matching is observed. Good agreement between calculations and experimental observations is obtained. Intermodal four-wave mixing is achieved experimentally with a conversion efficiency of 17%.

  16. Four-wave mixing in nanosecond pulsed fiber amplifiers.

    PubMed

    Fève, Jean-Philippe; Schrader, Paul E; Farrow, Roger L; Kliner, Dahv A V

    2007-04-16

    We present an experimental and theoretical analysis of four-wave mixing in nanosecond pulsed amplifiers based on double-clad ytterbium-doped fibers. This process leads to saturation of the amplified pulse energy at 1064 nm and to distortion of the spectral and temporal profiles. These behaviours are well described by a simple model considering both Raman and four-wave-mixing contributions. The role of seed laser polarization in birefringent fibers is also presented. These results point out the critical parameters and possible tradeoffs for optimization.

  17. Optical solitons with DWDM technology and four-wave mixing

    NASA Astrophysics Data System (ADS)

    Ekici, Mehmet; Zhou, Qin; Sonmezoglu, Abdullah; Moshokoa, Seithuti P.; Ullah, Malik Zaka; Biswas, Anjan; Belic, Milivoj

    2017-07-01

    This paper obtains bright and singular optical soliton solutions to DWDM system in presence of four-wave mixing. The extended trial function scheme is adopted. The two types of nonlinear media studied are Kerr law and parabolic law. There are other types of waves that appears as a byproduct to this scheme.

  18. Parametric four-wave mixing using a single cw laser.

    PubMed

    Brekke, E; Alderson, L

    2013-06-15

    Four-wave mixing can be used to generate coherent output beams, with frequencies difficult to acquire in commercial lasers. Here, a single narrow external cavity diode laser locked to the two photon 5s-5d transition in rubidium is combined with a tapered amplifier system to produce a high power cw beam at 778 nm and used to generate coherent light at 420 nm through parametric four-wave mixing. This process is analyzed in terms of the intensity and frequency of the incoming beam as well as the atomic density of the sample. The efficiency of the process is currently limited when on resonance due to the absorption of the 420 nm beam, and modifications should allow a significant increase in output power.

  19. Coherent Light Generation Using Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Brekke, Erik; Alderson, Laura

    2013-05-01

    Four-wave mixing can be used to generate coherent, diffraction limited output beams, with frequencies difficult to acquire in commercial lasers. Here a narrow ECDL locked to the two photon 5s-5d transition in Rubidium, combined with a tapered amplifier system, generates a high power cw beam at 778 which is used to generate coherent light at 420 nm through parametric four-wave mixing. By controlling both the intensity and frequency of the incoming beam, this process has been optimized, and the frequency dependence analyzed. The efficiency of the process is limited when on resonance, and further investigations are underway to increase efficiency and characterize the frequency of the generated beam.

  20. Resonant four-wave mixing of laser radiation in plasmas

    SciTech Connect

    Lal, A.; Joshi, C. )

    1991-10-01

    Experimental evidence of resonant four-wave mixing of CO{sub 2} laser radiation in a plasma is presented for the first time to our knowledge. Comparison of the experiment with theory indicates that, while collisions lead to a narrow spectral width of the ion acoustic resonance, convection and detuning owing to laser heating limit the enhancement of the signal reflectivity to below the expected value.

  1. Real-time image deblurring using four-wave mixing

    NASA Astrophysics Data System (ADS)

    Ja, Y. H.

    1983-09-01

    A real-time image deblurring method that uses four-wave mixing and is based on the deconvolution method developed by Stroke and others (Stroke and Zech, 1967; Stroke et al., 1969; Stroke and Halioua, 1970; and Stroke et al., 1977) is proposed. It is pointed out that the deconvolution method involves spatial filtering with a holographic deconvolution filter, where image division in the Fourier transform plane is performed. Since the deconvolution (division) filter is usually recorded on a negative photographic film by controlling gamma, the slope in the linear region of the Hurter-Driffield curve of the film, it is not possible to perform the operation in real time. With four-wave mixing, the recording of the hologram and the reconstruction of the image occur simultaneously and are almost in real time since the time-consuming processing of the film is not required. The general principle of image deblurring is outlined, and it is then shown how four-wave mixing in the nonlinear region can effect real-time image deblurring.

  2. Optimization of Quantum Correlation in Cascaded Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Feng, Jingliang; Jing, Jietai

    2017-03-01

    We propose a measurement strategy that can be used to optimize quantum correlation for a cascaded four-wave mixing (FWM) structure. By calculating the covariance matrix of a cascaded FWM structure, we can get all the correlations between any two parties in the outputs. We then calculate the eigenvalues and corresponding eigenmodes of the covariance matrix to find the squeezing degrees of the squeezed modes. Our theoretical model can explain our previous experimental results very well and is useful to optimize the squeezing degree in the cascaded FWM structure.

  3. Indirect precise angular control using four-wave mixing

    SciTech Connect

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

    2014-04-28

    Here, we show indirect precise angular control using a four-wave mixing (FWM) process. This was performed with a superposition of light with orbital angular momentum in an M-Type configuration of a hot {sup 85}Rb atomic ensemble. A gear-shaped interference pattern is observed at FWM light with a donut-shaped input signal. The gear could be rotated and is controlled through the change of the polarization of the pump laser. Our experimental results that are based on nonlinear coherent interactions have applications in image processing and precise angular control.

  4. Autoresonant four-wave mixing in optical fibers

    SciTech Connect

    Yaakobi, O.; Friedland, L.

    2010-08-15

    A theory of autoresonant four-wave mixing in tapered fibers is developed in application to optical parametric amplification (OPA). In autoresonance, the interacting waves (two pump waves, a signal, and an idler) stay phase-locked continuously despite variation of system parameters (spatial tapering). This spatially extended phase-locking allows complete pump depletion in the system and uniform amplification spectrum in a wide frequency band. Different aspects of autoresonant OPA are described including the automatic initial phase-locking, conditions for autoresonant transition, stability, and spatial range of the autoresonant interaction.

  5. Propagation analysis of forward degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Maruani, A.

    1980-05-01

    The problem of forward degenerate four-wave mixing in one- and two-photon absorbing media is shown to be analytically solvable for all current experimental conditions. The resonant interaction is studied in detail, and optical Kerr effect, auto and induced two-photon absorption, and nonlinear gain are taken explicitly into account. It is demonstrated how the Kerr effect limits the efficiency of the process. Around a two-photon resonance, the problem of the nearly parallel propagation of two beams undergoing auto and induced two-photon absorption is solved. The solutions are obtained in a form simple enough to allow numerical computations on a programmable calculator.

  6. Nondegenerate four-wave mixing in rubidium vapor: Transient regime

    SciTech Connect

    Becerra, F. E.; Willis, R. T.; Rolston, S. L.; Orozco, L. A.; Carmichael, H. J.

    2010-10-15

    We investigate the transient response of the generated light from four-wave mixing (FWM) in the diamond configuration using a step-down field excitation. The transients show fast decay times and oscillations that depend on the detunings and intensities of the fields. A simplified model taking into account the thermal motion of the atoms, propagation, absorption, and dispersion effects shows qualitative agreement with the experimental observations with the energy levels in rubidium (5S{sub 1/2}, 5P{sub 1/2}, 5P{sub 3/2}, and 6S{sub 1/2}). The atomic polarization comes from all the contributions of different velocity classes of atoms in the ensemble modifying dramatically the total transient behavior of the light from FWM.

  7. Four-Wave Mixing in Landau-Quantized Graphene.

    PubMed

    König-Otto, Jacob C; Wang, Yongrui; Belyanin, Alexey; Berger, Claire; de Heer, Walter A; Orlita, Milan; Pashkin, Alexej; Schneider, Harald; Helm, Manfred; Winnerl, Stephan

    2017-04-12

    For Landau-quantized graphene, featuring an energy spectrum consisting of nonequidistant Landau levels, theory predicts a giant resonantly enhanced optical nonlinearity. We verify the nonlinearity in a time-integrated degenerate four-wave mixing (FWM) experiment in the mid-infrared spectral range, involving the Landau levels LL-1, LL0 and LL1. A rapid dephasing of the optically induced microscopic polarization on a time scale shorter than the pulse duration (∼4 ps) is observed, while a complementary pump-probe experiment under the same experimental conditions reveals a much longer lifetime of the induced population. The FWM signal shows the expected field dependence with respect to lowest order perturbation theory for low fields. Saturation sets in for fields above ∼6 kV/cm. Furthermore, the resonant behavior and the order of magnitude of the third-order susceptibility are in agreement with our theoretical calculations.

  8. Degenerate four-wave mixing in silicon hybrid plasmonic waveguides.

    PubMed

    Duffin, Thorin J; Nielsen, Michael P; Diaz, Fernando; Palomba, Stefano; Maier, Stefan A; Oulton, Rupert F

    2016-01-01

    Silicon-based plasmonic waveguides show high confinement well beyond the diffraction limit. Various devices have been demonstrated to outperform their dielectric counterparts at micrometer scales, such as linear modulators, capable of generating high field confinement and improving device efficiency by increasing access to nonlinear processes, limited by ohmic losses. By using hybridized plasmonic waveguide architectures and nonlinear materials, silicon-based plasmonic waveguides can generate strong nonlinear effects over just a few wavelengths. We have theoretically investigated the nonlinear optical performance of two hybrid plasmonic waveguides (HPWG) with three different nonlinear materials. Based on this analysis, the hybrid gap plasmon waveguide (HGPW), combined with the DDMEBT nonlinear polymer, shows a four-wave mixing (FWM) conversion efficiency of -16.4  dB over a 1 μm propagation length, demonstrating that plasmonic waveguides can be competitive with standard silicon photonics structures over distances three orders of magnitude shorter.

  9. Frequency transitions in phononic four-wave mixing

    NASA Astrophysics Data System (ADS)

    Ganesan, Adarsh; Do, Cuong; Seshia, Ashwin

    2017-08-01

    This work builds upon the recent demonstration of a phononic four-wave mixing pathway mediated by parametric resonance. In such a process, drive tones fd 1 and fd 2 associated with a specific phonon mode interact such that one of the drive tones also parametrically excites a second mode at a sub-harmonic frequency and such interactions result in a frequency comb f/d1 2 ±n (" separators="|fd 1-fd 2 ). However, the specific behaviour associated with the case where both drive tones can independently excite the sub-harmonic phonon mode has not been studied or previously described. While it may be plausible to expect the merger of two frequency combs f/d1 2 ±n (" separators="|fd 1-fd 2 ) and f/d2 2 ±n (" separators="|fd 1-fd 2 ), this paper indicates that only one of these mechanisms is selected and also shows an interesting transition linked to this process. The frequency transitions from f/d1 2 ±n (" separators="|fd 1-fd 2 ) to f/d2 2 ±n (" separators="|fd 1-fd 2 ) holds promise for computing applications.

  10. Enhanced four-wave mixing with nonlinear plasmonic metasurfaces.

    PubMed

    Jin, Boyuan; Argyropoulos, Christos

    2016-06-27

    Plasmonic metasurfaces provide an effective way to increase the efficiency of several nonlinear processes while maintaining nanoscale dimensions. In this work, nonlinear metasurfaces based on film-coupled silver nanostripes loaded with Kerr nonlinear material are proposed to achieve efficient four-wave mixing (FWM). Highly localized plasmon resonances are formed in the nanogap between the metallic film and nanostripes. The local electric field is dramatically enhanced in this subwavelength nanoregion. These properties combined with the relaxed phase matching condition due to the ultrathin area lead to a giant FWM efficiency, which is enhanced by nineteen orders of magnitude compared to a bare silver screen. In addition, efficient visible and low-THz sources can be constructed based on the proposed nonlinear metasurfaces. The FWM generated coherent wave has a directional radiation pattern and its output power is relatively insensitive to the incident angles of the excitation sources. This radiated power can be further enhanced by increasing the excitation power. The dielectric nonlinear material placed in the nanogap is mainly responsible for the ultrastrong FWM response. Compact and efficient wave mixers and optical sources spanning different frequency ranges are envisioned to be designed based on the proposed nonlinear metasurface designs.

  11. Degenerate four-wave mixing in triply resonant Kerr cavities

    NASA Astrophysics Data System (ADS)

    Ramirez, David M.; Rodriguez, Alejandro W.; Hashemi, Hila; Joannopoulos, J. D.; Soljačić, Marin; Johnson, Steven G.

    2011-03-01

    We demonstrate theoretical conditions for highly efficient degenerate four-wave mixing in triply resonant nonlinear (Kerr) cavities. We employ a general and accurate temporal coupled-mode analysis in which the interaction of light in arbitrary microcavities is expressed in terms of a set of coupling coefficients that we rigorously derive from the full Maxwell equations. Using the coupled-mode theory, we show that light consisting of an input signal of frequency ω0-Δω can, in the presence of pump light at ω0, be converted with quantum-limited efficiency into an output shifted signal of frequency ω0+Δω, and we derive expressions for the critical input powers at which this occurs. We find the critical powers in the order of 10 mW, assuming very conservative cavity parameters (modal volumes ~10 cubic wavelengths and quality factors ~1000). The standard Manley-Rowe efficiency limits are obtained from the solution of the classical coupled-mode equations, although we also derive them from simple photon-counting “quantum” arguments. Finally, using a linear stability analysis, we demonstrate that maximal conversion efficiency can be retained even in the presence of self- and cross-phase modulation effects that generally act to disrupt the resonance condition.

  12. Enhanced four-wave mixing with nonlinear plasmonic metasurfaces

    PubMed Central

    Jin, Boyuan; Argyropoulos, Christos

    2016-01-01

    Plasmonic metasurfaces provide an effective way to increase the efficiency of several nonlinear processes while maintaining nanoscale dimensions. In this work, nonlinear metasurfaces based on film-coupled silver nanostripes loaded with Kerr nonlinear material are proposed to achieve efficient four-wave mixing (FWM). Highly localized plasmon resonances are formed in the nanogap between the metallic film and nanostripes. The local electric field is dramatically enhanced in this subwavelength nanoregion. These properties combined with the relaxed phase matching condition due to the ultrathin area lead to a giant FWM efficiency, which is enhanced by nineteen orders of magnitude compared to a bare silver screen. In addition, efficient visible and low-THz sources can be constructed based on the proposed nonlinear metasurfaces. The FWM generated coherent wave has a directional radiation pattern and its output power is relatively insensitive to the incident angles of the excitation sources. This radiated power can be further enhanced by increasing the excitation power. The dielectric nonlinear material placed in the nanogap is mainly responsible for the ultrastrong FWM response. Compact and efficient wave mixers and optical sources spanning different frequency ranges are envisioned to be designed based on the proposed nonlinear metasurface designs. PMID:27345755

  13. Stimulated degenerate four-wave mixing in Si nanocrystal waveguides

    NASA Astrophysics Data System (ADS)

    Manna, Santanu; Bernard, Martino; Biasi, Stefano; Ramiro Manzano, Fernando; Mancinelli, Mattia; Ghulinyan, Mher; Pucker, George; Pavesi, Lorenzo

    2016-07-01

    Parametric frequency conversion via four-wave mixing (FWM) in silicon nanocrystal (Si NC) waveguides is observed at 1550 nm. To investigate the role of Si NC, different types of waveguides containing Si NC in a SiO2 matrix were fabricated. Owing to the increase of the dipole oscillator strength mediated by the quantum confinement effect, the non-linear refractive index ({n}2) of Si NCs is found to be more than one order of magnitude larger than the one of bulk Si. Coupled differential equations for the degenerate FWM process taking into account the role of Si NC were numerically solved to model the experimental data. The modeling yields an effective {n}2 for Si NCs in SiO2 waveguides which is similar to the one of Si waveguides. We also measured a large signal to idler conversion bandwidth of ∼22 nm. The large non-linear refractive index is joined with a large two photon absorption coefficient which makes the use of Si NC in non-linear optical devices mostly suitable for mid-infrared applications.

  14. Four-wave mixing experiments with extreme ultraviolet transient gratings.

    PubMed

    Bencivenga, F; Cucini, R; Capotondi, F; Battistoni, A; Mincigrucci, R; Giangrisostomi, E; Gessini, A; Manfredda, M; Nikolov, I P; Pedersoli, E; Principi, E; Svetina, C; Parisse, P; Casolari, F; Danailov, M B; Kiskinova, M; Masciovecchio, C

    2015-04-09

    Four-wave mixing (FWM) processes, based on third-order nonlinear light-matter interactions, can combine ultrafast time resolution with energy and wavevector selectivity, and enable the exploration of dynamics inaccessible by linear methods. The coherent and multi-wave nature of the FWM approach has been crucial in the development of advanced technologies, such as silicon photonics, subwavelength imaging and quantum communications. All these technologies operate at optical wavelengths, which limits the spatial resolution and does not allow the probing of excitations with energy in the electronvolt range. Extension to shorter wavelengths--that is, the extreme ultraviolet and soft-X-ray ranges--would allow the spatial resolution to be improved and the excitation energy range to be expanded, as well as enabling elemental selectivity to be achieved by exploiting core resonances. So far, FWM applications at such wavelengths have been prevented by the absence of coherent sources of sufficient brightness and of suitable experimental set-ups. Here we show how transient gratings, generated by the interference of coherent extreme-ultraviolet pulses delivered by the FERMI free-electron laser, can be used to stimulate FWM processes at suboptical wavelengths. Furthermore, we have demonstrated the possibility of observing the time evolution of the FWM signal, which shows the dynamics of coherent excitations as molecular vibrations. This result opens the way to FWM with nanometre spatial resolution and elemental selectivity, which, for example, would enable the investigation of charge-transfer dynamics. The theoretical possibility of realizing these applications has already stimulated ongoing developments of free-electron lasers: our results show that FWM at suboptical wavelengths is feasible, and we hope that they will enable advances in present and future photon sources.

  15. Four wave mixing experiments with extreme ultraviolet transient gratings

    PubMed Central

    Bencivenga, F.; Cucini, R.; Capotondi, F.; Battistoni, A.; Mincigrucci, R.; Giangrisostomi, E.; Gessini, A.; Manfredda, M.; Nikolov, I. P.; Pedersoli, E.; Principi, E.; Svetina, C.; Parisse, P.; Casolari, F.; Danailov, M. B.; Kiskinova, M.; Masciovecchio, C.

    2015-01-01

    Four wave mixing (FWM) processes, based on third-order non-linear light-matter interactions, can combine ultrafast time resolution with energy and wavevector selectivity, and enables to explore dynamics inaccessible by linear methods.1-7 The coherent and multi-wave nature of FWM approach has been crucial in the development of cutting edge technologies, such as silicon photonics,8 sub-wavelength imaging9 and quantum communications.10 All these technologies operate with optical wavelengths, which limit the spatial resolution and do not allow probing excitations with energy in the eV range. The extension to shorter wavelengths, that is the extreme ultraviolet (EUV) and soft-x-ray (SXR) range, will allow to improve the spatial resolution and to expand the excitation energy range, as well as to achieve elemental selectivity by exploiting core resonances.5-7,11-14 So far FWM applications at these wavelengths have been prevented by the absence of coherent sources of sufficient brightness and suitable experimental setups. Our results show how transient gratings, generated by the interference of coherent EUV pulses delivered by the FERMI free electron laser (FEL),15 can be used to stimulate FWM processes at sub-optical wavelengths. Furthermore, we have demonstrated the possibility to read the time evolution of the FWM signal, which embodies the dynamics of coherent excitations as molecular vibrations. This result opens the perspective for FWM with nanometer spatial resolution and elemental selectivity, which, for example, would enable the investigation of charge-transfer dynamics.5-7 The theoretical possibility to realize these applications have already stimulated dedicated and ongoing FEL developments;16-20 today our results show that FWM at sub-optical wavelengths is feasible and would be the spark to the further advancements of the present and new sources. PMID:25855456

  16. Four-wave mixing experiments with extreme ultraviolet transient gratings

    NASA Astrophysics Data System (ADS)

    Bencivenga, F.; Cucini, R.; Capotondi, F.; Battistoni, A.; Mincigrucci, R.; Giangrisostomi, E.; Gessini, A.; Manfredda, M.; Nikolov, I. P.; Pedersoli, E.; Principi, E.; Svetina, C.; Parisse, P.; Casolari, F.; Danailov, M. B.; Kiskinova, M.; Masciovecchio, C.

    2015-04-01

    Four-wave mixing (FWM) processes, based on third-order nonlinear light-matter interactions, can combine ultrafast time resolution with energy and wavevector selectivity, and enable the exploration of dynamics inaccessible by linear methods. The coherent and multi-wave nature of the FWM approach has been crucial in the development of advanced technologies, such as silicon photonics, subwavelength imaging and quantum communications. All these technologies operate at optical wavelengths, which limits the spatial resolution and does not allow the probing of excitations with energy in the electronvolt range. Extension to shorter wavelengths--that is, the extreme ultraviolet and soft-X-ray ranges--would allow the spatial resolution to be improved and the excitation energy range to be expanded, as well as enabling elemental selectivity to be achieved by exploiting core resonances. So far, FWM applications at such wavelengths have been prevented by the absence of coherent sources of sufficient brightness and of suitable experimental set-ups. Here we show how transient gratings, generated by the interference of coherent extreme-ultraviolet pulses delivered by the FERMI free-electron laser, can be used to stimulate FWM processes at suboptical wavelengths. Furthermore, we have demonstrated the possibility of observing the time evolution of the FWM signal, which shows the dynamics of coherent excitations as molecular vibrations. This result opens the way to FWM with nanometre spatial resolution and elemental selectivity, which, for example, would enable the investigation of charge-transfer dynamics. The theoretical possibility of realizing these applications has already stimulated ongoing developments of free-electron lasers: our results show that FWM at suboptical wavelengths is feasible, and we hope that they will enable advances in present and future photon sources.

  17. Nonlinear Optical Studies of Rydberg Atoms Using Degenerate Four-Wave Mixing.

    DTIC Science & Technology

    1984-08-01

    AD-Ai46 827 NONLINEAR OPTICAL STUDIES OF RYDBERG ATOMS USING 1/2 DEGENERATE FOUR -WAVE MIXING(U) HUGHES RESEARCH LABS MALIBU CA J F LAM ET AL. AUG 84...146 827 NONLINEAR OPTICAL STUDIES OF RYDBERG ATOMS USING DEGENERATE FOUR -WAVE MIXING J.F. Lam, R.A. McFarlane, and D.G. StMel Hughes Research...techniques were developed nearly degenerate four -wave mixing, polarization nearly degenerate four -wave mixing, fre- quency domain three-state

  18. Influence of stimulated Raman scattering on the conversion efficiency in four wave mixing

    SciTech Connect

    Wunderlich, R.; Moore, M.A.; Garrett, W.R.; Payne, M.G.

    1988-01-01

    Secondary nonlinear optical effects following parametric four wave mixing in sodium vapor are investigated. The generated ultraviolet radiation induces stimulated Raman scattering and other four wave mixing process. Population transfer due to Raman transitions strongly influences the phase matching conditions for the primary mixing process. Pulse shortening and a reduction in conversion efficiency are observed. 8 refs., 3 figs.

  19. Degenerate Four-Wave Mixing Measurements of High Order Nonlinearities in Semiconductors

    DTIC Science & Technology

    1991-10-01

    2274 IEEE JOURNAL OF QUANTUM ELECTRONICS. VOL. 27, NO. IO. OCTOBER 1991 Degenerate Four -Wave Mixing Measurements of High Order Nonlinearities in... four -wave mixing experi- ments on ZnSe and CdTe semiconductor samples with pico- second laser pulses at wavelengths below the bandgap. Nonlin- earities...three-photon absorption. I. INTRODUCTION WE repo~ ~ series of picose~ond degenerate four -wave mixmg (DFWM) studies conducted in ZnSe and CdTe at

  20. Study of Two-Photon Reseonant Four Wave Sum Mixing in Xeon and its Competition with the Four Wave Difference Mixing

    NASA Astrophysics Data System (ADS)

    Al-Basheer, W.; Shi, Y. J.

    2009-06-01

    The two-photon resonant four wave sum- and difference-mixing in Xe gaseous medium was studied by subjecting a variety of molecular samples, including acetone, furan, triethylamine (TEA), and dimethylsilacyclobutane (DMSCB), to the laser sources produced from the four wave mixing processes for ionization. Ionization of acetone-h6, acetone-d6, furan-h4, furan-h4, and DMSCB samples showed similar behaviour. It is demonstrated that in a vacuum ultraviolet (VUV) spectral region of 103 - 109 nm four-wave sum mixing in Xe can only occur in ten discontinued regions, all of which are to the blue of a Xe atomic transition. Study of the TEA sample with its ionization potential lower than the photon energy of the VUV radiation from the difference mixing illustrated the competition between the sum- and difference-mixing occurring simultaneously in the Xe gas cell.

  1. Collinear Four-Wave Mixing of Two-Component Matter Waves

    SciTech Connect

    Pertot, Daniel; Gadway, Bryce; Schneble, Dominik

    2010-05-21

    We demonstrate atomic four-wave mixing of two-component matter waves in a collinear geometry. Starting from a single-species Bose-Einstein condensate, seed and pump modes are prepared through microwave state transfer and state-selective Kapitza-Dirac diffraction. Four-wave mixing then populates the initially empty output modes. Simulations based on a coupled-mode expansion of the Gross-Pitaevskii equation are in very good agreement with the experimental data. We show that four-wave mixing can play an important role in studies of bosonic mixtures in optical lattices. Moreover, our system should be of interest in the context of quantum atom optics.

  2. Collinear four-wave mixing of two-component matter waves.

    PubMed

    Pertot, Daniel; Gadway, Bryce; Schneble, Dominik

    2010-05-21

    We demonstrate atomic four-wave mixing of two-component matter waves in a collinear geometry. Starting from a single-species Bose-Einstein condensate, seed and pump modes are prepared through microwave state transfer and state-selective Kapitza-Dirac diffraction. Four-wave mixing then populates the initially empty output modes. Simulations based on a coupled-mode expansion of the Gross-Pitaevskii equation are in very good agreement with the experimental data. We show that four-wave mixing can play an important role in studies of bosonic mixtures in optical lattices. Moreover, our system should be of interest in the context of quantum atom optics.

  3. Transient Gratings, Four-Wave Mixing and Polariton Effects in Nonlinear Optics

    DTIC Science & Technology

    1991-06-01

    AD-A251 947 m’NAIO lim oi iTrnsiene Gracn as Four -Wave Mixing and PDlariton EffecS. U~~ ua J. Knoester and S. Mukamel 7. P(OPWO ,~ O*tGANIZAflNM...restricted geometries. The transient grating and it$ fequency-oan analogue (dbgfat four wave mixing) awe used 10 iluste the formalm in both the sucag and...acid-free paper. TRANSIENT GRATINGS, FOUR -WAVE MIXING AND POLARITON EFFECTS IN NONLINEAR OPTICS Jasper KNOESTER Unive’rsitY o1 (roningen. Department of

  4. Simultaneous chromatic dispersion monitoring and optical modulation format identification utilizing four wave mixing

    NASA Astrophysics Data System (ADS)

    Cui, Sheng; Qiu, Chen; Ke, Changjian; He, Sheng; Liu, Deming

    2015-11-01

    This paper presents a method which is able to monitor the chromatic dispersion (CD) and identify the modulation format (MF) of optical signals simultaneously. This method utilizes the features of the output curve of the highly sensitive all-optical CD monitor based on four wave mixing (FWM). From the symmetric center of the curve CD can be estimated blindly and independently, while from the profile and convergence region of the curve ten commonly used modulation formats can be recognized with simple algorithm based on maximum correlation classifier. This technique does not need any high speed optoelectronics and has no limitation on signal rate. Furthermore it can tolerate large CD distortions and is robust to polarization mode dispersion (PMD) and amplified spontaneous emission (ASE) noise.

  5. Degenerate four wave mixing in large mode area hybrid photonic crystal fibers.

    PubMed

    Petersen, Sidsel R; Alkeskjold, Thomas T; Lægsgaard, Jesper

    2013-07-29

    Spontaneous degenerate four wave mixing (FWM) is investigated in large mode area hybrid photonic crystal fibers, in which photonic bandgap guidance and index guidance is combined. Calculations show the parametric gain is maximum on the edge of a photonic bandgap, for a large range of pump wavelengths. The FWM products are observed on the edges of a transmission band experimentally, in good agreement with the numerical results. Thereby the bandedges can be used to control the spectral positions of FWM products through a proper fiber design. The parametric gain control combined with a large mode area fiber design potentially allows for power scaling of light at wavelengths not easily accessible with e.g. rare earth ions.

  6. Impact of signal-ASE four-wave mixing on the effectiveness of digital back-propagation in 112 Gb/s PM-QPSK systems.

    PubMed

    Rafique, Danish; Ellis, Andrew D

    2011-02-14

    Limitations in the performance of coherent transmission systems employing digital back-propagation due to four-wave mixing impairments are reported for the first time. A significant performance constraint is identified, originating from four-wave mixing between signals and amplified spontaneous emission noise which induces a linear increase in the standard deviation of the received field with signal power, and linear dependence on transmission distance.

  7. [Study on phase-matching of four-wave mixing spectrum in photonic crystal fiber].

    PubMed

    Liu, Xiao-xu; Wang, Shu-tao; Zhao, Xing-tao; Chen, Shuang; Zhou, Gui-yao; Wu, Xi-jun; Li, Shu-guang; Hou, Lan-Tian

    2014-06-01

    In the present paper, the four-wave mixing principle of fiber was analyzed, and the high-gain phase-matching conditions were shown. The nonlinear coefficient and dispersion characteristics of photonic crystal fibers were calculated by multipole method. The phase mismatch characteristics of fibers with multiple zero-dispersion wavelengths were analyzed for the first time. The changing rules of phase matching wavelength with the pump wavelength and the pump power were obtained, and the phase matching curves were shown. The characteristics of phase matching wavelengths for different dispersion curves were analyzed. There are four new excitation wavelengths of four-wave mixing spectrum in two zero-dispersion wavelength photonic crystal fiers. Four-wave mixing spectroscopy of photonic crystal fibers with two zero-dispersion wavelengths was obtained in the experi-ent, which is consistent with the theoretical analysis, and verified the reliability of the phase matching theory. The fiber with multiple zero-dispersion wavelengths can create a ricbhphase-matching topology, excite more four-wave mixing wavelengths, ena-ling enhanced control over the spectral locations of the four-wave mixing and resonant-radiation bands emitted by solitons and short pulses. These provide theoretical guidance for photonic crystal fiber wavelength conversion and supercontinoum generation based on four-wave mixing.

  8. Four-wave mixing microscopy: a high potential nonlinear imaging method

    NASA Astrophysics Data System (ADS)

    Ehmke, Tobias; Knebl, Andreas; Heisterkamp, Alexander

    2015-03-01

    In this work we present non-resonant four-wave mixing microscopy as an additional contrast mechanism in nonlinear microscopy. The setup for this technique was based on a commercially available multiphoton microscope setup equipped with a titanium:sapphire-laser and an optical parametric oscillator as light sources. Fundamental system characteristics with respect to the spatio-temporal pulse overlap and the influence of aberrations on the process are presented. Experiments regarding the directionality of the four-wave mixing signal performed on fresh porcine meat showed an average ratio of the backward to forward signal mean intensity of 0.16 +/- 0.01. Nevertheless, structural information is comparable for both detection modalities. This highlights the potential of four-wave mixing microscopy for in vivo applications. Furthermore, results on porcine meat show the additional contrast generated by four-wave mixing. In summary, the results show a great potential of non-resonant four-wave mixing microscopy as label-free imaging modality in the biomedical sciences.

  9. Energy correlations of photon pairs generated by a silicon microring resonator probed by Stimulated Four Wave Mixing

    PubMed Central

    Grassani, Davide; Simbula, Angelica; Pirotta, Stefano; Galli, Matteo; Menotti, Matteo; Harris, Nicholas C.; Baehr-Jones, Tom; Hochberg, Michael; Galland, Christophe; Liscidini, Marco; Bajoni, Daniele

    2016-01-01

    Compact silicon integrated devices, such as micro-ring resonators, have recently been demonstrated as efficient sources of quantum correlated photon pairs. The mass production of integrated devices demands the implementation of fast and reliable techniques to monitor the device performances. In the case of time-energy correlations, this is particularly challenging, as it requires high spectral resolution that is not currently achievable in coincidence measurements. Here we reconstruct the joint spectral density of photons pairs generated by spontaneous four-wave mixing in a silicon ring resonator by studying the corresponding stimulated process, namely stimulated four wave mixing. We show that this approach, featuring high spectral resolution and short measurement times, allows one to discriminate between nearly-uncorrelated and highly-correlated photon pairs. PMID:27032688

  10. Energy correlations of photon pairs generated by a silicon microring resonator probed by Stimulated Four Wave Mixing.

    PubMed

    Grassani, Davide; Simbula, Angelica; Pirotta, Stefano; Galli, Matteo; Menotti, Matteo; Harris, Nicholas C; Baehr-Jones, Tom; Hochberg, Michael; Galland, Christophe; Liscidini, Marco; Bajoni, Daniele

    2016-04-01

    Compact silicon integrated devices, such as micro-ring resonators, have recently been demonstrated as efficient sources of quantum correlated photon pairs. The mass production of integrated devices demands the implementation of fast and reliable techniques to monitor the device performances. In the case of time-energy correlations, this is particularly challenging, as it requires high spectral resolution that is not currently achievable in coincidence measurements. Here we reconstruct the joint spectral density of photons pairs generated by spontaneous four-wave mixing in a silicon ring resonator by studying the corresponding stimulated process, namely stimulated four wave mixing. We show that this approach, featuring high spectral resolution and short measurement times, allows one to discriminate between nearly-uncorrelated and highly-correlated photon pairs.

  11. Enhancing four-wave-mixing processes by nanowire arrays coupled to a gold film.

    PubMed

    Poutrina, Ekaterina; Ciracì, Cristian; Gauthier, Daniel J; Smith, David R

    2012-05-07

    We consider the process of four-wave mixing in an array of gold nanowires strongly coupled to a gold film. Using full-wave simulations, we perform a quantitative comparison of the four-wave mixing efficiency associated with a bare film and films with nanowire arrays. We find that the strongly localized surface plasmon resonances of the coupled nanowires provide an additional local field enhancement that, along with the delocalized surface plasmon of the film, produces an overall four-wave mixing efficiency enhancement of up to six orders of magnitude over that of the bare film. The enhancement occurs over a wide range of excitation angles. The film-coupled nanowire array is easily amenable to nanofabrication, and could find application as an ultra-compact component for integrated photonic and quantum optic systems.

  12. 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

  13. Four-wave mixing analysis of quantum dot semiconductor lasers for linewidth enhancement factor extraction.

    PubMed

    Lin, Chih-Hao; Lin, Hung-Hsin; Lin, Fan-Yi

    2012-01-02

    We apply a four-wave mixing analysis on a quantum dot laser to simultaneously obtain the linewidth enhancement factor α and other intrinsic laser parameters. By fitting the experimentally obtained regenerative signals and power spectra at different detuning frequencies with the respective curves analytically calculated from the rate equations, parameters including the linewidth enhancement factor, the carrier decay rate in the dots, the differential gain, and the photon decay rate can be determined all at once under the same operating conditions. In this paper, a theoretical model for the four-wave mixing analysis of the QD lasers is derived and verified. The sensitivity and accuracy of the parameter extraction using the four-wave mixing method are presented. Moreover, how each each parameters alter the shapes of the regenerative signals and the power spectra are also discussed.

  14. Strongly modified four-wave mixing in a coupled semiconductor quantum dot-metal nanoparticle system

    NASA Astrophysics Data System (ADS)

    Paspalakis, Emmanuel; Evangelou, Sofia; Kosionis, Spyridon G.; Terzis, Andreas F.

    2014-02-01

    We study the four-wave mixing effect in a coupled semiconductor quantum dot-spherical metal nanoparticle structure. Depending on the values of the pump field intensity and frequency, we find that there is a critical distance that changes the form of the spectrum. Above this distance, the four-wave mixing spectrum shows an ordinary three-peaked form and the effect of controlling its magnitude by changing the interparticle distance can be obtained. Below this critical distance, the four-wave mixing spectrum becomes single-peaked; and as the interparticle distance decreases, the spectrum is strongly suppressed. The behavior of the system is explained using the effective Rabi frequency that creates plasmonic metaresonances in the hybrid structure. In addition, the behavior of the effective Rabi frequency is explained via an analytical solution of the density matrix equations.

  15. Entangled photon generation using four-wave mixing in azimuthally symmetric microresonators.

    PubMed

    Camacho, Ryan M

    2012-09-24

    A novel quantum mechanical formulation of the bi-photon wavefunction and spectra resulting from four-wave mixing is developed for azimuthally symmetric systems. Numerical calculations are performed verifying the use of the angular group velocity and angular group velocity dispersion in such systems, as opposed their commonly used linear counterparts. The dispersion profile and bi-photon spectra of two illustrative examples are given, emphasizing the physical origin of the effects leading to the conditions for angular momentum and energy conservation. A scheme is proposed in which widely spaced narrowband entangled photons may be produced through a four-wave mixing process in a chip-scale ring resonator. The entangled photon pairs are found to conserve energy and momentum in the four-wave mixing interaction, even though both photon modes lie in spectral regions of steep angular group velocity dispersion.

  16. Four-wave mixing instabilities in photonic-crystal and tapered fibers.

    PubMed

    Biancalana, F; Skryabin, D V; Russell, P St J

    2003-10-01

    Four-wave mixing instabilities are theoretically studied for continuous wave propagation in ultrasmall core photonic-crystal and tapered fibers. The waveguide, or geometrical, contribution to the overall dispersion of these structures is much stronger than in conventional fibers. This leads to the appearance of unstable frequency bands that are qualitatively and quantitatively different from those seen in conventional fibers. The four-wave mixing theory developed here is based on the full wave equation, which allows rigorous study of the unstable bands even when the detunings are of the order of the pump frequency itself. Solutions obtained using the generalized nonlinear Schrödinger equation, which is an approximate version of the full wave equation, reveal that it suffers from several deficiencies when used to describe four-wave mixing processes.

  17. Multi-photon microscopy based on resonant four-wave mixing of colloidal quantum dots

    NASA Astrophysics Data System (ADS)

    Masia, F.; Langbein, W.; Borri, P.

    2009-02-01

    We demonstrate a novel multi-photon imaging modality based on the detection of four-wave mixing (FWM) from colloidal nanoparticles. Four-wave mixing is a third-order signal which can be excited and detected in resonance with the ground-state excitonic transition of CdSe/ZnS quantum dots. The coherent FWM signal is detected interferometrically to reject incoherent backgrounds for improved image contrast compared to fluorescence methods. We measure transversal and axial resolutions of 140nm and 590nm respectively, significantly beating the one-photon diffraction limit. We also demonstrate optical imaging of quantum-dot-labeled Golgi structures of HepG2 cells.

  18. Enhanced four-wave mixing via photonic bandgap coupled defect resonances.

    PubMed

    Blair, S

    2005-05-16

    Frequency conversion efficiency via four-wave mixing in coupled 1-D photonic crystal defect structures is studied numerically. In structures where all interacting frequencies coincide with intraband defect resonances, energy conversion efficiencies greater than 5% are predicted. Because the frequency spacings are determined by the free-spectral range, thereby requiring long defects for small spacings using intraband resonances, four-wave mixing using coupled-defect miniband resonances in more compact structures is also studied. Conversion efficiencies of greater than 1% are obtained in this case.

  19. Effects of four-wave mixing on light propagating in an EIT medium

    NASA Astrophysics Data System (ADS)

    Lauk, Nikolai; O'Brien, Christopher; Fleischhauer, Michael

    2013-05-01

    The typical EIT media consist of Λ type atoms where a propagating signal field is resonant with an optical transition which is coupled by a strong resonant laser to an adjacent transition. Quantum interference makes the medium transparent to the signal. In many EIT experiments, the driving laser also acts as a far-detuned field on the signal transition, which for high optical depth causes a four-wave mixing (FWM) process. The far-detuned field generates a new co-propagating idler field which gives rise to gain for the signal field. The presence of gain introduces noise on the signal field, due to both spontaneous emission as well as a vacuum contributions of the idler. Using the Heisenberg-Langevin approach and solving the corresponding Maxwell-Bloch equations for the propagating field operators in a EIT FWM medium, we find analytic expressions for the noise and discuss the effect of FWM on EIT experiments, such as those done for EIT based quantum memories.

  20. Four-wave mixing and generation of short pulses in multimode class B laser amplifiers

    NASA Astrophysics Data System (ADS)

    Jahanpanah, J.; Moradi, H.

    2013-04-01

    The linear and nonlinear amplification features of an optical signal by a multimode class B laser have been discussed. The four-wave mixing process between the cavity central mode and the amplified input signal produces a sequence of satellite lines. It is demonstrated that short pulses can be formed by phase beating the satellite lines. In the linear regime, the laser amplifier acts like a three-mode free-running laser where the oscillations of two right and left adjacent modes are substituted by those of the amplified input signal and its image satellite line. In the nonlinear regime, two more symmetrical adjacent satellite lines are first added to the cavity electric field components and then the frequency of the cavity central mode is shifted towards the image satellite lines. At the same time, the number of central-mode photons is gradually decreased by raising the input signal strength. The central-mode photons are ultimately reduced to zero, where an injection-locking phenomenon takes place. Finally, we derive a heuristic conservation relation between the input energies to the laser by sum of the pumping and injected signals, and those distributed between the signal and image satellite lines and spontaneous emission radiation.

  1. Two-photon-state generation via four-wave mixing in optical fibers

    SciTech Connect

    Chen Jun; Li Xiaoying; Kumar, Prem

    2005-09-15

    A quantum theory of two-photon-state generation via four-wave mixing in optical fibers is studied, with emphasis on the case where the pump is a classical, narrow (picosecond-duration) pulse. One of the experiments performed in our lab is discussed and analyzed. Numerical predictions from the theory are shown to be in good agreement with the experimental results.

  2. Image processing by four-wave mixing in photorefractive GaAs

    NASA Technical Reports Server (NTRS)

    Gheen, Gregory; Cheng, Li-Jen

    1987-01-01

    Three image processing experiments were performed by degenerate four-wave mixing in photorefractive GaAs. The experiments were imaging by phase conjugation, edge enhancement, and autocorrelation. The results show that undoped, semiinsulating, liquid-encapsulated Czochralski-grown GaAs crystals can be used as effective optical processing media despite their small electrooptic coefficient.

  3. Optical triple-in digital logic using nonlinear optical four-wave mixing

    NASA Astrophysics Data System (ADS)

    Widjaja, Joewono; Tomita, Yasuo

    1995-08-01

    A new programmable optical processor is proposed for implementing triple-in combinatorial digital logic that uses four-wave mixing. Binary-coded decimal-to-octal decoding is experimentally demonstrated by use of a photorefractive BaTiO 3 crystal. The result confirms the feasibility of the proposed system.

  4. Correlation coefficient measurement of the mode-locked laser tones using four-wave mixing.

    PubMed

    Anthur, Aravind P; Panapakkam, Vivek; Vujicic, Vidak; Merghem, Kamel; Lelarge, Francois; Ramdane, Abderrahim; Barry, Liam P

    2016-06-01

    We use four-wave mixing to measure the correlation coefficient of comb tones in a quantum-dash mode-locked laser under passive and active locked regimes. We study the uncertainty in the measurement of the correlation coefficient of the proposed method.

  5. Four-wave mixing for clock recovery of phase modulated optical OFDM superchannel.

    PubMed

    Power, Mark J; Jia, Wei; Webb, Roderick P; Manning, Robert J; Gunning, Fatima C Garcia

    2014-03-24

    We simulate and experimentally demonstrate a novel all-optical clock recovery technique for a BPSK OFDM superchannel. Four-wave mixing in SOAs is used to strip the modulation from the superchannel sub-carriers, two of which are filtered and beat together in a photodiode to recover the clock.

  6. Interference between Raman gain and four-wave mixing in cold atoms

    SciTech Connect

    Michaud, Franck; Kaiser, Robin; Gattobigio, Giovanni-Luca; Tabosa, Jose W. R.

    2007-10-15

    Using a pump-probe scheme with a large cloud of cold rubidium atoms, we observe very large double-pass gain (1800%) due to interference between Raman gain and four-wave mixing. A simple model explains the main features observed.

  7. Image processing by four-wave mixing in photorefractive GaAs

    NASA Technical Reports Server (NTRS)

    Gheen, Gregory; Cheng, Li-Jen

    1987-01-01

    Three image processing experiments were performed by degenerate four-wave mixing in photorefractive GaAs. The experiments were imaging by phase conjugation, edge enhancement, and autocorrelation. The results show that undoped, semiinsulating, liquid-encapsulated Czochralski-grown GaAs crystals can be used as effective optical processing media despite their small electrooptic coefficient.

  8. Optical imaging through turbid media with a degenerate four-wave mixing correlation time gate

    DOEpatents

    Sappey, Andrew D.

    1998-04-14

    Optical imaging through turbid media is demonstrated using a degenerate four-wave mixing correlation time gate. An apparatus and method for detecting ballistic and/or snake light while rejecting unwanted diffusive light for imaging structures within highly scattering media are described. Degenerate four-wave mixing (DFWM) of a doubled YAG laser in rhodamine 590 is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore has lost memory of the structures within the scattering medium. Images have been obtained of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye, which demonstrates the utility of DFWM for imaging through turbid media. Use of DFWM as an ultrafast time gate for the detection of ballistic and/or snake light in optical mammography is discussed.

  9. Monitoring Gold Nanoparticle Growth in Situ via the Acoustic Vibrations Probed by Four-Wave Mixing.

    PubMed

    Wu, Jian; Xiang, Dao; Gordon, Reuven

    2017-02-21

    We monitor in situ gold nanoparticle growth in aqueous solution by probing the acoustic vibrations with four-wave mixing. We observe two acoustic vibrational modes of gold nanoparticles from the nonlinear optical response: an extensional mode with longitudinal expansion and transverse contraction and a breathing mode with radial expansion and contraction. The mode frequencies, which show an inverse dependence on the nanoparticle diameter, allow one to monitor the nanoparticle size and size distribution during synthesis. The information about the nanoparticle size and size distribution calculated on the basis of the mode frequencies agrees well with the results obtained from the electron microscopy analysis, validating the four-wave mixing technique as an accurate and effective tool for in situ monitoring of colloidal growth.

  10. High resolution spectroscopy and spectral simulation of C2 using degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Lloyd, G. M.; Ewart, P.

    1999-01-01

    Degenerate four-wave mixing in the sub-Doppler phase conjugate geometry was used to record high resolution spectra of the d 3Πg-a3Πu (0-0) Swan band of C2 produced in an oxy-acetylene flame. The line positions of isolated transitions were measured to an accuracy of ˜3×10-3 cm-1 and calibrated using a Fizeau interferometer system. The data obtained from these spectra was used to calculate rotational constants and lambda doubling parameters for the 3Π states from which the line positions for the whole band were calculated. Noticeable improvements between experimental and calculated line positions are seen when compared to previously published values. The effect of inaccuracies in line positions on the simulation of degenerate four-wave mixing spectra is discussed and some examples of the improvement in simulation using the newly calculated line positions are presented.

  11. Classical-to-quantum transition with broadband four-wave mixing.

    PubMed

    Vered, Rafi Z; Shaked, Yaakov; Ben-Or, Yelena; Rosenbluh, Michael; Pe'er, Avi

    2015-02-13

    A key question of quantum optics is how nonclassical biphoton correlations at low power evolve into classical coherence at high power. Direct observation of the crossover from quantum to classical behavior is desirable, but difficult due to the lack of adequate experimental techniques that cover the ultrawide dynamic range in photon flux from the single photon regime to the classical level. We investigate biphoton correlations within the spectrum of light generated by broadband four-wave mixing over a large dynamic range of ∼80  dB in photon flux across the classical-to-quantum transition using a two-photon interference effect that distinguishes between classical and quantum behavior. We explore the quantum-classical nature of the light by observing the interference contrast dependence on internal loss and demonstrate quantum collapse and revival of the interference when the four-wave mixing gain in the fiber becomes imaginary.

  12. Coherent Fano resonances in a plasmonic nanocluster enhance optical four-wave mixing

    PubMed Central

    Zhang, Yu; Wen, Fangfang; Zhen, Yu-Rong; Nordlander, Peter; Halas, Naomi J.

    2013-01-01

    Plasmonic nanoclusters, an ordered assembly of coupled metallic nanoparticles, support unique spectral features known as Fano resonances due to the coupling between their subradiant and superradiant plasmon modes. Within the Fano resonance, absorption is significantly enhanced, giving rise to highly localized, intense near fields with the potential to enhance nonlinear optical processes. Here, we report a structure supporting the coherent oscillation of two distinct Fano resonances within an individual plasmonic nanocluster. We show how this coherence enhances the optical four-wave mixing process in comparison with other double-resonant plasmonic clusters that lack this property. A model that explains the observed four-wave mixing features is proposed, which is generally applicable to any third-order process in plasmonic nanostructures. With a larger effective susceptibility χ(3) relative to existing nonlinear optical materials, this coherent double-resonant nanocluster offers a strategy for designing high-performance third-order nonlinear optical media. PMID:23690571

  13. Metal-free flat lens using negative refraction by nonlinear four-wave mixing.

    PubMed

    Cao, Jianjun; Zheng, Yuanlin; Feng, Yaming; Chen, Xianfeng; Wan, Wenjie

    2014-11-21

    A perfect lens with unlimited resolution has always posed a challenge to both theoretical and experimental physicists. Recent developments in optical metamaterials promise an attractive approach towards perfect lenses using negative refraction to overcome the diffraction limit, improving resolution. However, those artificially engineered metamaterials are usually accompanied by high losses from metals and are extremely difficult to fabricate. An alternative proposal using negative refraction by four-wave mixing has attracted much interest recently, though most existing experiments still require metals and none of them have been implemented for an optical lens. Here, we experimentally demonstrate a metal-free flat lens for the first time using negative refraction by degenerate four-wave mixing with a thin glass slide. We realize an optical lensing effect utilizing a nonlinear refraction law, which may have potential applications in microscopy.

  14. Four-wave mixing and edge-enhanced optical correlation in a Ce:KNSBN crystal.

    PubMed

    Liang, B; Wang, Z; Guan, J; Mu, G; Cartwright, C M

    2000-08-01

    In the case of degenerate four-wave mixing in a cerium-doped potassium sodium strontium barium niobate (Ce:KNSBN) crystal, it is found that the transmission grating is dominant when the incident beams are extraordinarily polarized, the crystal response is more rapid, and the conjugate beam is more intense. Furthermore, the variation of the conjugate beam intensity forms a loop as the fringe modulation of the transmission grating varies. Based on this observation, we have implemented edge enhancement of an image and edge-enhanced optical correlation via four-wave mixing in a Ce:KNSBN crystal without the requirement of reversal of the signal-pump-beam intensity ratio.

  15. Carbon nanotube/polymer composite coated tapered fiber for four wave mixing based wavelength conversion.

    PubMed

    Xu, Bo; Omura, Mika; Takiguchi, Masato; Martinez, Amos; Ishigure, Takaaki; Yamashita, Shinji; Kuga, Takahiro

    2013-02-11

    In this paper, we demonstrate a nonlinear optical device based on a fiber taper coated with a carbon nanotube (CNT)/polymer composite. Using this device, four wave mixing (FWM) based wavelength conversion of 10 Gb/s Non-return-to-zero signal is achieved. In addition, we investigate wavelength tuning, two photon absorption and estimate the effective nonlinear coefficient of the CNTs embedded in the tapered fiber to be 1816.8 W(-1)km(-1).

  16. Numerical analysis of multiwavelength erbium-doped fiber ring laser exploiting four-wave mixing.

    PubMed

    Xu, Xiaochuan; Yao, Yong; Chen, Deying

    2008-08-04

    In this paper, a model is proposed to study the behavior of four-wave mixing assisted multiwavelength erbium doped fiber ring laser based on the theoretical model of the multiple FWM processes and Gile's theory of erbium-doped fiber. It is demonstrated that the mode competition can be effectively suppressed through FWM. The effect of phase matching, the nonlinear coefficient, the power in the cavity and the length of the nonlinear medium on output spectrum uniformity are also investigated.

  17. Silicon-on-Sapphire Waveguides: Mode-converting Couplers and Four-wave Mixing

    DTIC Science & Technology

    2014-09-01

    dominance. Previous investigations show that this spectral range is of interest for applications that include free-space communications, laser radar... laser radar. The goal of this project is to develop mid-infrared transmitters for these applications by utilizing a four-wave mixing process...modulation laser sources, still have inferior perform- ance compared to telecom band devices, therefore hindering the performance of mid-infrared

  18. Femtosecond Degenerate Four-Wave-Mixing in ZnO Microcrystallite Thin Films

    NASA Astrophysics Data System (ADS)

    Zhang, Wei-li; Wang, Qing-yue; Chai, Lu; Xing, Qi-rong; K, Wong S.; H, Wang; Z, Tang K.; G, Wong K. L.; R, Jain

    1999-06-01

    Transient third-order optical nonlinearity χ(3) of ZnO microcrystallite thin films is measured at various temperatures by using femtosecond degenerate four-wave-mixing. Room-temperature excitonic enhancement of χ(3) is observed. The magnitude of χ(3) ranges between 10-4 to 10-6 esu from 4.2 K to room temperature. The measured χ(3) response time ranging from 200 to 300 fs is ultrafast for temperature down to 4.2 K.

  19. Experimental demonstration of optical switching and routing via four-wave mixing spatial shift.

    PubMed

    Nie, Zhiqiang; Zheng, Huaibin; Zhang, Yanpeng; Zhao, Yan; Zuo, Cuicui; Li, Changbiao; Chang, Hong; Xiao, Min

    2010-01-18

    We demonstrate the shift characteristics of four-wave mixing (FWM) beam spots which are controlled by the strong laser fields via the large cross-Kerr nonlinearity. The shift distances and directions are determined by the nonlinear dispersions. Based on such spatial displacements of the FWM beams, as well as the probe beam, we experimentally demonstrate spatial optical switching for one beam or multiple optical beams, which can be used for all-optical switching, switching arrays and routers.

  20. Bunching-induced asymmetry in degenerate four-wave mixing with cold atoms

    SciTech Connect

    Gattobigio, G. L.; Michaud, F.; Kaiser, R.; Javaloyes, J.

    2006-10-15

    We have investigated degenerate four-wave mixing in a sample of cold rubidium atoms. A red-blue asymmetry is observed for high intensities of the pumping beams. This asymmetry is explained by the spatial bunching of the atoms in the nodes or antinodes of the strong standing wave of the pump beams. This explanation is confirmed by different experimental configurations and by numerical simulations.

  1. Observation of four-wave mixing in slow-light silicon photonic crystal waveguides.

    PubMed

    McMillan, James F; Yu, Mingbin; Kwong, Dim-Lee; Wong, Chee Wei

    2010-07-19

    Four-wave mixing is observed in a silicon W1 photonic crystal waveguide. The dispersion dependence of the idler conversion efficiency is measured and shown to be enhanced at wavelengths exhibiting slow group velocities. A 12-dB increase in the conversion efficiency is observed. Concurrently, a decrease in the conversion bandwidth is observed due to the increase in group velocity dispersion in the slow-light regime. The experimentally observed conversion efficiencies agree with the numerically modeled results.

  2. Four-wave mixing analysis of quantum dot and quantum well lasers

    NASA Astrophysics Data System (ADS)

    Lin, Hung-Hsin; Lin, Chih-Hao; Lin, Fan-Yi

    2011-02-01

    In this paper, we characterize and compare a quantum dot and a quantum well lasers using the four-wave mixing analysis. The optical and power spectra of the four-wave mixing state in the quantum dot laser are studied both numerically and experimentally. The tendency of the amplitude versus detuning in the quantum dot laser is very similar to those seen in the quantum well laser. The four-wave mixing signals and the power spectra from both lasers are symmetric, while asymmetry in the regenerated signal is found. Compared to the quantum well lasers, the higher resonance peak of the regenerated signal of the quantum dot lasers appears on the opposite side of the detuning in the optical spectra. The intrinsic parameters of the lasers are also obtained by fitting the optical spectra and power spectra obtained experimentally with those derived directly from the rate equations. The measured value of the linewidth enhancement factor has a good agreement with that obtained by the injection locking method.

  3. Studies of degenerate and nearly degenerate four wave mixing of laser radiation in plasmas

    SciTech Connect

    Joshi, Chan . Dept. of Electrical Engineering)

    1990-12-01

    Optical Phase Conjugation is an area of nonlinear optics with a wide variety of potential applications. One method of generating as phase conjugate signal is with four wave mixing (FWM). In FWM, three input beams interact in a nonlinear medium, and a fourth beam is produced that is the phase conjugate of one of the input waves. Degeneate Four Wave Mixing (DFWM) is a special case of FWM in which all of the beams are at the same frequency. In a plasma, DFWM is an effective technique for phase conjugation in high density, low temperature plasmas. One way of enhancing the phase conjugate signal over and above the DFWM level is with Resonant Four Wave Mixing (RFWM), in which two of the input beams beat at a plasma resonance. In addition to enhancing the generated wave, RFWM can also serve as a diagnostic for many plasma parameters, such as the electron and ion temperatures, the ion acoustic velocity, and the damping rate. In this report, experimental evidence of RFWM with CO{sub 2} laser radiation (10.6 {mu}m) is presented, and the data is compared with theoretical predictions.

  4. Robust and compact entanglement generation from diode-laser-pumped four-wave mixing

    SciTech Connect

    Lawrie, B. J.; Yang, Y.; Eaton, M.; Black, A. N.; Pooser, R. C.

    2016-04-11

    Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein- Podolsky-Rosen entanglement and intensity difference squeezing. Recently, diode-laser-pumped four-wave mixing processes have been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generated by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. In conclusion, this robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.

  5. Robust and compact entanglement generation from diode-laser-pumped four-wave mixing

    DOE PAGES

    Lawrie, B. J.; Yang, Y.; Eaton, M.; ...

    2016-04-11

    Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein- Podolsky-Rosen entanglement and intensity difference squeezing. Recently, diode-laser-pumped four-wave mixing processes have been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generatedmore » by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. In conclusion, this robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.« less

  6. Robust and compact entanglement generation from diode-laser-pumped four-wave mixing

    SciTech Connect

    Lawrie, B. J. Pooser, R. C.; Yang, Y.; Eaton, M.; Black, A. N.

    2016-04-11

    Four-wave-mixing processes are now routinely used to demonstrate multi-spatial-mode Einstein-Podolsky-Rosen entanglement and intensity difference squeezing. Diode-laser-pumped four-wave mixing processes have recently been shown to provide an affordable, compact, and stable source for intensity difference squeezing, but it was unknown if excess phase noise present in power amplifier pump configurations would be an impediment to achieving quadrature entanglement. Here, we demonstrate the operating regimes under which these systems are capable of producing entanglement and under which excess phase noise produced by the amplifier contaminates the output state. We show that Einstein-Podolsky-Rosen entanglement in two mode squeezed states can be generated by a four-wave-mixing source deriving both the pump field and the local oscillators from a tapered-amplifier diode-laser. This robust continuous variable entanglement source is highly scalable and amenable to miniaturization, making it a critical step toward the development of integrated quantum sensors and scalable quantum information processors, such as spatial comb cluster states.

  7. Measurement of Coherence Decay in GaMnAs Using Femtosecond Four-wave Mixing

    PubMed Central

    Webber, Daniel; de Boer, Tristan; Yildirim, Murat; March, Sam; Mathew, Reuble; Gamouras, Angela; Liu, Xinyu; Dobrowolska, Margaret; Furdyna, Jacek; Hall, Kimberley

    2013-01-01

    The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system.  Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization.  The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted.  The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism.  We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques.   This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics. PMID:24326982

  8. Vortex algebra by multiply cascaded four-wave mixing of femtosecond optical beams.

    PubMed

    Hansinger, Peter; Maleshkov, Georgi; Garanovich, Ivan L; Skryabin, Dmitry V; Neshev, Dragomir N; Dreischuh, Alexander; Paulus, Gerhard G

    2014-05-05

    Experiments performed with different vortex pump beams show for the first time the algebra of the vortex topological charge cascade, that evolves in the process of nonlinear wave mixing of optical vortex beams in Kerr media due to competition of four-wave mixing with self-and cross-phase modulation. This leads to the coherent generation of complex singular beams within a spectral bandwidth larger than 200nm. Our experimental results are in good agreement with frequency-domain numerical calculations that describe the newly generated spectral satellites.

  9. Ultrasonic probes of aqueous particle suspensions: Collinear four-wave mixing and resonator detuning

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, Christopher Scott

    The interaction of sound with sound in a suspension can be mediated by the suspension's response to acoustic radiation pressure. The current investigations involve acoustical four-wave mixing mediated by a suspension with collinear pump and probe waves, and the effects of sound on the resonant frequency of a system. The suspension includes hollow glass or polystyrene microparticles in a deionized water/sugar or water/salt mixture designed to make the particles neutrally buoyant. Radiation pressure from counter propagating pump beams induces a periodic grating in the number density of the microspheres, due to the particles difference in compressibility from that of the host solution. The pump beams are formed by the transmission and repeated reverberations of a wave produced by a single ceramic pump transducer that is reflected off a receiver. The pump wave is in the stopband. In the case of four-wave mixing, the Bragg scattering amplitude was measured using the pump transducer as the probe source and a piezoelectric thin film hydrophone as a receiver, with both parallel to the standing pump wave nodal planes. Reflection coefficients as a function of time and frequency are calculated by comparing the reflected and transmitted probe waves. By increasing the particle concentration, total Bragg reflectivities from the established grating reaching 20% have been seen, which is still in the region of agreement between the Born approximation and transfer matrix theory. Bragg scattering by gratings of gas bubbles caused by cavitation was also detected. The redistribution of the suspended particles in the standing wavefield shifts the resonant frequency of the chamber. Adiabatic invariance theory and a transfer matrix approach agree with the experimental results. Some interesting results, including a form of mode-hopping, were also observed. The dynamics of the grating formation and dissolution have been studied using both four-wave mixing and frequency shift measurements

  10. Graphene Near-Degenerate Four-Wave Mixing for Phase Characterization of Broadband Pulses in Ultrafast Microscopy.

    PubMed

    Ciesielski, Richard; Comin, Alberto; Handloser, Matthias; Donkers, Kevin; Piredda, Giovanni; Lombardo, Antonio; Ferrari, Andrea C; Hartschuh, Achim

    2015-08-12

    We investigate near-degenerate four-wave mixing in graphene using femtosecond laser pulse shaping microscopy. Intense near-degenerate four-wave mixing signals on either side of the exciting laser spectrum are controlled by amplitude and phase shaping. Quantitative signal modeling for the input pulse parameters shows a spectrally flat phase response of the near-degenerate four-wave mixing due to the linear dispersion of the massless Dirac Fermions in graphene. Exploiting these properties we demonstrate that graphene is uniquely suited for the intrafocus phase characterization and compression of broadband laser pulses, circumventing disadvantages of common methods utilizing second or third harmonic light.

  11. Real-time monitoring of graphene patterning with wide-field four-wave mixing microscopy

    NASA Astrophysics Data System (ADS)

    Koivistoinen, Juha; Aumanen, Jukka; Hiltunen, Vesa-Matti; Myllyperkiö, Pasi; Johansson, Andreas; Pettersson, Mika

    2016-04-01

    The single atom thick two-dimensional graphene is a promising material for various applications due to its extraordinary electronic, optical, optoelectronic, and mechanical properties. The demand for developing graphene based applications has entailed a requirement for development of methods for fast imaging techniques for graphene. Here, we demonstrate imaging of graphene with femtosecond wide-field four-wave mixing microscopy. The method provides a sensitive, non-destructive approach for rapid large area characterization of graphene. We show that the method is suitable for online following of a laser patterning process of microscale structures on single-layer graphene.

  12. Real-time monitoring of graphene patterning with wide-field four-wave mixing microscopy

    SciTech Connect

    Koivistoinen, Juha; Aumanen, Jukka; Myllyperkiö, Pasi; Pettersson, Mika; Hiltunen, Vesa-Matti; Johansson, Andreas

    2016-04-11

    The single atom thick two-dimensional graphene is a promising material for various applications due to its extraordinary electronic, optical, optoelectronic, and mechanical properties. The demand for developing graphene based applications has entailed a requirement for development of methods for fast imaging techniques for graphene. Here, we demonstrate imaging of graphene with femtosecond wide-field four-wave mixing microscopy. The method provides a sensitive, non-destructive approach for rapid large area characterization of graphene. We show that the method is suitable for online following of a laser patterning process of microscale structures on single-layer graphene.

  13. Optical imaging through turbid media using a degenerate-four-wave mixing correlation time gate

    SciTech Connect

    Bigio, I.J.; Strauss, C.E.M.; Zerkle, D.K.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The authors have demonstrated the use of a degenerate-four-wave-mixing time gate to allow imaging through turbid media, with potential application to tissue imaging. A near infrared (NIR), long-pulse Cr{sup +3}:Li{sub 2}SrAlF{sub 6} laser was used as the light source (during most the project) for imaging through clear and turbid media. Preliminary experiments were also carried out with a continuous diode laser.

  14. Degenerate four-wave mixing from layered semiconductor clusters in the quantum size regime

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; Rhee, Bum Ku; McGinnis, Brian P.; Sandroff, Claude J.

    1986-11-01

    We report the first measurement of the third-order nonlinear susceptibility χ(3) in layered semiconductor clusters exhibiting pronounced quantum size effects at room temperature. BiI3 clusters prepared in colloidal form in acetonitrile had a thickness of ≂7 Å and lateral dimensions between 60 and 90 Å. Using degenerate four-wave mixing, we observed that the conjugate pulses from the small and the large gratings had comparable intensities, verifying the electronic origin of the nonlinearity. The nonlinear susceptibility was found to be 2.3×10-11 esu for a colloid with a cluster volume fraction of 10-5.

  15. Application of four wave mixing in precise radio frequency dissemination via optical fiber link

    NASA Astrophysics Data System (ADS)

    Lu, Xing; Lv, Zhiqiang; Chen, Xing; Gong, Zibo; Shi, Kebin

    2014-09-01

    We report on a new phase noise detection technique for radio frequency (RF) dissemination based on transferring mode locked laser pulses via optical fiber. The proposed approach is insusceptible to optical fiber interconnection reflection by combining optical frequency comb (OFC) expansion generated by four wave mixing (FWM) in dispersion shifted fiber (DSF) and wavelength division multiplexing (WDM) technique. An experimental system based on a fiber link of 100km was demonstrated. The measured fractional stability was 1.5×10-13 at 1s and 1.7×10-16 at 1000s.

  16. Saturation effects and inhomogeneous broadening in Doppler-free degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Steel, D. G.; Lam, J. F.

    1981-12-01

    We have performed experiments to study the saturation properties of degenerate four-wave mixing (DFWM) in inhomogeneously broadened material. The experiments were performed on line-center in SF 6 using a CW CO 2 laser on the P16 line at 10.6 μm. Measured peak reflectivities of 1.7 x 10 -4 are in reasonable agreement with a simple two-level model. This model also appears to correctly account for the observed saturation effects. While the material is clearly inhomogeneously broadened, both the experimental and theoretical reflectivity scale as though the material was homogeneously broadened.

  17. Observation of multi-component spatial vector solitons of four-wave mixing.

    PubMed

    Wang, Ruimin; Wu, Zhenkun; Zhang, Yiqi; Zhang, Zhaoyang; Yuan, Chenzhi; Zheng, Huaibin; Li, Yuanyuan; Zhang, Jinhai; Zhang, Yanpeng

    2012-06-18

    We report the observation of multi-component dipole and vortex vector solitons composed of eight coexisting four-wave mixing (FWM) signals in two-level atomic system. The formation and stability of the multi-component dipole and vortex vector solitons are observed via changing the experiment parameters, including the frequency detuning, powers, and spatial configuration of the involved beams and the temperature of the medium. The transformation between modulated vortex solitons and rotating dipole solitons is observed at different frequency detunings. The interaction forces between different components of vector solitons are also investigated.

  18. Quantum properties of parametric four-wave mixing in a Raman-type atomic system

    NASA Astrophysics Data System (ADS)

    Sharypov, A. V.; He, Bing; Arkhipkin, V. G.; Myslivets, S. A.

    2017-05-01

    We present a study of the quantum properties of two light fields used in parametric four-wave mixing in a Raman-type atomic system. The system realizes an effective Hamiltonian of beam-splitter-type coupling between the light fields, which allows one to control squeezing and amplitude distribution of the light fields, as well as realizing their entanglement. The scheme can be feasibly applied to engineer the quantum properties of two single-mode light fields in properly chosen input states.

  19. Phase-matching and mitigation of four-wave mixing in fibers with positive gain.

    PubMed

    Fève, Jean-Philippe

    2007-01-22

    We present a theoretical study of four-wave mixing interactions in fibers in the presence of gain. In contrast to passive fibers, positive gain at the pump wavelength leads to constructive generation of the signal and idler waves, even in the case of large phase-mismatch, so that FWM processes can be very efficient even in isotropic single-mode fibers with normal dispersion. We also propose simple ways to mitigate these parametric interactions by applying a controlled variation of the phase-mismatch along the fiber. These concepts apply to all optical amplifiers.

  20. Two-photon resonant four-wave mixing in a dressed atomic system

    NASA Astrophysics Data System (ADS)

    Sun, Jiang; Zuo, Zhanchun; Mi, Xin; Yu, Zuhe; Jiang, Qian; Wang, Yanbang; Wu, Ling-An; Fu, Panming

    2004-11-01

    We study two-photon resonant nondegenerate four-wave mixing (NFWM) in a dressed cascade four-level system. In the presence of a strong coupling field, the two-photon resonant NFWM spectrum exhibits Autler-Townes splitting, accompanied by either suppression or enhancement of the NFWM signal. Such phenomena are demonstrated in Ba through inducing of atomic coherence between the ground state 6s2 and the doubly excited autoionizing Rydberg state 6pnd . This technique provides a spectroscopic tool for measuring not only the resonant frequency and dephasing rate but also the transition dipole moment between two highly excited atomic states.

  1. Spectrally resolved four-wave mixing experiments on bulk GaAs with 14-fs pulses

    SciTech Connect

    Wehner, M.U.; Steinbach, D.; Wegener, M.; Marschner, T.; Stolz, W.

    1996-05-01

    We investigate the coherent dynamics at the band edge of GaAs at low temperatures for carrier densities ranging from 4.3{times}10{sup 14} cm{sup {minus}3} to 4.4{times}10{sup 17} cm{sup {minus}3} by means of spectrally resolved transient four-wave mixing with 14-fs pulses. At large nonequilibrium carrier densities we observe oscillations with an energy-dependent oscillation period related to interference among continuum states. The experimental findings are compared with a simple model. This comparison delivers a weak energy dependence of dephasing in the initial buildup phase of screening. {copyright} {ital 1996 Optical Society of America.}

  2. Solitons of four-wave mixing in competing cubic-quintic nonlinearity.

    PubMed

    Wu, Zhenkun; Zhang, Yunzhe; Ullah, Zakir; Jiang, Tao; Yuan, Chenzhi

    2015-04-06

    We experimentally investigate the soliton formation and dynamics in the nonlinear propagation of the generated signal and probe beams in four-wave mixing (FWM) process with atomic coherence in a three-level atomic system, under the competition between focusing and defocusing nonlinearities, as well as between gain and dissipation, due to the third- and fifth-order nonlinear susceptibilities with opposite signs. With multi-parameter controllability and nonlinear competition in the system, fundamental, dipole, and azimuthally-modulated vortex FWM solitons can transform mutually from one to the other. Such investigations have potential applications in optical pattern formation and control, and all-optical communication.

  3. Theory of slow light enhanced four-wave mixing in photonic crystal waveguides.

    PubMed

    Santagiustina, M; Someda, C G; Vadalà, G; Combrié, S; De Rossi, A

    2010-09-27

    The equations for Four-Wave-Mixing in a Photonic Crystal waveguide are derived accurately. The dispersive nature of slow-light enhancement, the impact of Bloch mode reshaping in the nonlinear overlap integrals and the tensor nature of the third order polarization are therefore taken into account. Numerical calculations reveal substantial differences with simpler models, which increase with decreasing group velocity. We predict that the gain for a 1.3 mm long, unoptimized GaInP waveguide will exceed 10 dB if the pump power exceeds 1 W.

  4. Designing slow-light photonic crystal waveguides for four-wave mixing applications.

    PubMed

    Kanakis, Panagiotis; Kamalakis, Thomas; Sphicopoulos, Thomas

    2014-02-15

    We discuss the optimization of photonic crystal waveguides for four-wave mixing (FWM) applications, taking into account linear loss and free-carrier effects. Suitable figures of merit are introduced in order to guide us through the choice of practical, high-efficiency designs requiring relatively low pump power and small waveguide length. In order to realistically perform the waveguide optimization process, we propose and validate an approximate expression for the FWM efficiency, which significantly alleviates our numerical calculations. Promising waveguide designs are identified by means of an exhaustive search, altering some structural parameters. Our approach aims to optimize the waveguides for nonlinear signal-processing applications based on the FWM.

  5. Intermodal four-wave mixing from femtosecond pulse-pumped photonic crystal fiber.

    PubMed

    Tu, H; Jiang, Z; Marks, D L; Boppart, S A

    2009-03-09

    Large Stokes-shift ( approximately 4700 cm(-1)) four-wave mixing is generated in a deeply normal dispersion regime from a 20 cm commercial large-mode-area photonic crystal fiber pumped by amplified approximately 800 nm femtosecond pulses. The phase-matching condition is realized through an intermodal scheme involving two pump photons in the fundamental fiber mode and a pair of Stokesanti-Stokes photons in a higher-order fiber mode. Over 7% conversion efficiency from the pump input to 586 nm anti-Stokes signal has been attained.

  6. Four-wave mixing stability in hybrid photonic crystal fibers with two zero-dispersion wavelengths.

    PubMed

    Sévigny, Benoit; Vanvincq, Olivier; Valentin, Constance; Chen, Na; Quiquempois, Yves; Bouwmans, Géraud

    2013-12-16

    The four-wave mixing process in optical fibers is generally sensitive to dispersion uniformity along the fiber length. However, some specific phase matching conditions show increased robustness to longitudinal fluctuations in fiber dimensions, which affect the dispersion, even for signal and idler wavelengths far from the pump. In this paper, we present the method by which this point is found, how the fiber design characteristics impact on the stable point and demonstrate the stability through propagation simulations using the non-linear Schrödinger equation.

  7. Designing photonic crystal waveguides for broadband four-wave mixing applications.

    PubMed

    Kanakis, Panagiotis; Kamalakis, Thomas; Sphicopoulos, Thomas

    2015-03-15

    We present photonic crystal waveguide designs which exhibit large four-wave mixing efficiencies over a wide wavelength region. These designs are identified using an optimization process taking into account sophisticated figure-of-merits that depend on the pump bandwidth and the signal/pump tunability. The obtained designs achieve up to -18.9  dB conversion efficiency, tunable over a 10 nm tunability range. We also present alternative designs that are less efficient but have smaller power requirements and are far more compact.

  8. Polarization properties of degenerate four-wave mixing in GaAs

    NASA Technical Reports Server (NTRS)

    Liu, Duncan T.; Cheng, Li-Jen

    1989-01-01

    The effect of an applied dc electric field on beam-polarization properties of degenerate four-wave mixing in GaAs is investigated. The results can be interpreted in terms of the phase retardation arising from the applied electric field and the light-induced periodic space-charge field. The conditions for attaining a cross-polarized diffracted beam and read beam are discussed. The experimental results agree reasonably well with the theoretical calculations for an applied voltage of 6 kV.

  9. Highly efficient picosecond degenerate four-wave mixing in a tellurite microstructured optical fiber

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Hoang Tuan, Tong; Kawamura, Harutaka; Nagasaka, Kenshiro; Suzuki, Takenobu; Ohishi, Yasutake

    2016-06-01

    Wavelength-tunable picosecond degenerate four-wave mixing was demonstrated in a tellurite microstructured optical fiber (TMOF). The zero-dispersion wavelength of the TMOF was shifted to 1570 nm by introducing a single ring of air holes in the cladding. The anti-Stokes signal sideband can be generated from 1490 to 1500 nm, and the Stokes idler sideband can emit from 1595 to 1645 nm. Because of the high nonlinearity of the TMOF and the large peak power of the picosecond pump, a maximal signal gain of 31.2 dB and an idler conversion efficiency of +35 dB were achieved.

  10. Opening four-wave mixing and six-wave mixing channels via dual electromagnetically induced transparency windows.

    PubMed

    Zhang, Yanpeng; Brown, Andy W; Xiao, Min

    2007-09-21

    Highly efficient four-wave mixing (FWM) and six-wave mixing (SWM) processes can coexist in a four-level Y-type atomic system due to atomic coherence. The simultaneously opened dual electromagnetically induced transparency windows in this four-level atomic system allow observation of these two nonlinear optical processes at the same time, which enables detailed studies of the interplay between the FWM and SWM processes. Three-photon and five-photon destructive interferences are also observed.

  11. Superradiant cascade emissions in an atomic ensemble via four-wave mixing

    SciTech Connect

    Jen, H.H.

    2015-09-15

    We investigate superradiant cascade emissions from an atomic ensemble driven by two-color classical fields. The correlated pair of photons (signal and idler) is generated by adiabatically driving the system with large-detuned light fields via four-wave mixing. The signal photon from the upper transition of the diamond-type atomic levels is followed by the idler one which can be superradiant due to light-induced dipole–dipole interactions. We then calculate the cooperative Lamb shift (CLS) of the idler photon, which is a cumulative effect of interaction energy. We study its dependence on a cylindrical geometry, a conventional setup in cold atom experiments, and estimate the maximum CLS which can be significant and observable. Manipulating the CLS of cascade emissions enables frequency qubits that provide alternative robust elements in quantum network. - Highlights: • Superradiance from a cascade atomic transition. • Correlated photon pair generation via four-wave mixing. • Dynamical light–matter couplings in a phased symmetrical state. • Cooperative Lamb shift in a cylindrical atomic ensemble.

  12. Highly efficient four wave mixing in GaInP photonic crystal waveguides.

    PubMed

    Eckhouse, V; Cestier, I; Eisenstein, G; Combrié, S; Colman, P; De Rossi, A; Santagiustina, M; Someda, C G; Vadalà, G

    2010-05-01

    We report highly efficient four wave mixing in a GaInP photonic crystal waveguide. Owing to its large bandgap, the ultrafast Kerr nonlinearity of GaInP is not diminished by two photon absorption and related carrier effects for photons in the 1550 nm range. A four-wave-mixing efficiency of -49 dB was demonstrated for cw pump and probe signals in the milliwatt range, while for pulsed pumps with a peak power of 25 mW the conversion efficiency increased to -36 dB. Measured conversion efficiency dependencies on pump probe detuning and on pump power are in excellent agreement with a simple analytical model from which the nonlinear parameter gamma is extracted. Gamma scales approximately with the square of the slow down factor and varies from 800 W(-1) m(-1) at a pump wavelength lambda(p)=1532 nm to 2900 W(-1) m(-1) at lambda(p)=1550 nm. These values are consistent with those obtained from self phase modulation experiments in similar devices.

  13. Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

    NASA Astrophysics Data System (ADS)

    van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

    2016-09-01

    Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

  14. Analysis of four-wave mixing between pulses in high-data-rate quasi-linear subchannel-multiplexed systems.

    PubMed

    Zweck, John; Menyuk, Curtis R

    2002-07-15

    We study four-wave mixing between pulses in two subchannels of a quasi-linear 40-Gbit/s subchannel-multiplexed system. For a pseudorandom bit string there are resonances in the mean of the ghost pulse energy and in the jitter of the energy in the marks as functions of the subchannel frequency spacing. However, away from these resonances the effect of four-wave mixing decreases as the subchannel spacing increases, permitting propagation over longer distances.

  15. All-optical switching via four-wave mixing Bragg scattering in a silicon platform

    NASA Astrophysics Data System (ADS)

    Zhao, Yun; Lombardo, David; Mathews, Jay; Agha, Imad

    2017-02-01

    We employ the process of non-degenerate four-wave mixing Bragg scattering to demonstrate all-optical control in a silicon platform. In our configuration, a strong, non-information-carrying pump is mixed with a weak control pump and an input signal in a silicon-on-insulator waveguide. Through the optical nonlinearity of this highly confining waveguide, the weak pump controls the wavelength conversion process from the signal to an idler, leading to a controlled depletion of the signal. The strong pump, on the other hand, plays the role of a constant bias. In this work, we show experimentally that it is possible to implement this low-power switching technique as a first step towards universal optical logic gates, and test the performance with random binary data. Even at very low powers, where the signal and control pump levels are almost equal, the eye-diagrams remain open, indicating a successful operation of the logic gates.

  16. Role of atomic coherence effects in four-wave mixing using autoionizing resonances

    NASA Astrophysics Data System (ADS)

    Anscombe, M. P.; de Nalda, R.; Kuçukkara, I.; Marangos, J. P.

    2003-10-01

    The generation of tunable, nanosecond-pulsed extreme-ultraviolet (EUV) light (84.92 nm to 84.97 nm ˜14.6 eV) using four-wave mixing in optically deep krypton gas was investigated experimentally and theoretically. The sum-frequency mixing scheme generated light from two overlapping autoionizing resonances, 17s' and 15d'. We investigated whether the laser-induced atomic coherence effect of electromagnetically induced transparency (EIT) could enhance the intensity of the EUV light generated. The maximum EUV output was seen from the region where the 15d' autoionizing resonance has a transparency window due to Fano-type quantum interference. An analytical model using appropriate atomic parameters explains how background absorption can prevent EIT enhancement of EUV generation; and shows how a background Raman-like coupling term in the nonlinear susceptibility can well describe the measured EUV generation spectrum.

  17. Microwave photonic notch filter with complex coefficient based on four wave mixing

    NASA Astrophysics Data System (ADS)

    Xu, Dong; Cao, Ye; Tong, Zheng-rong; Yang, Jing-peng

    2016-11-01

    A microwave photonic notch filter with a complex coefficient is proposed and demonstrated based on four wave mixing (FWM). FWM effect of two single-frequency laser beams occurs in a highly nonlinear fiber (HNLF), and multi-wavelength optical signals are generated and used to generate the multi-tap of microwave photonic filter (MPF). The complex coefficient is generated by using a Fourier-domain optical processor (FD-OP) to control the amplitude and phase of the optical carrier and phase modulation sidebands. The results show that this filter can be changed from bandpass filter to notch filter by controlling the FD-OP. The center frequency of the notch filter can be continuously tuned from 5.853 GHz to 29.311 GHz with free spectral range ( FSR) of 11.729 GHz. The shape of the frequency response keeps unchanged when the phase is tuned.

  18. Triply surface-plasmon resonant four-wave mixing imaging of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Masia, Francesco; Langbein, Wolfgang; Watson, Peter; Borri, Paola

    2011-03-01

    We have developed a novel multiphoton microscopy technique not relying on (and hence not limited by) fluorescence emission, which exploits the third-order nonlinearity called four-wave mixing of gold nanoparticles in resonance with their surface Plasmon. The coherent, transient and resonant nature of this signal allows its detection free from backgrounds that limit other contrast methods for gold nanoparticles. We show detection of single 10nm gold nanoparticles with low excitation intensities, corresponding to negligible average thermal heating. Owing to the the third-order nonlinearity we measure a transversal and axial resolution of 140nm and 470nm respectively, better than the one-photon diffraction limit. We also show high-contrast imaging of gold-labels down to 5nm size in Golgi structures of HepG2 cells at useful imaging speeds (10 kHz pixel rate). Thermal dissociation of gold nanoparticles from their bonding sites when varying the excitation intensity is also investigated.

  19. Format transparent, wide range and independent dispersion monitoring method based on four-wave mixing

    NASA Astrophysics Data System (ADS)

    Cui, Sheng; He, Sheng; Sun, Simin; Ke, Changjian; Liu, Deming

    2013-11-01

    In this paper we propose an improved all optical chromatic dispersion (CD) monitoring method based on highly nonlinear power transfer function (PTF) provided by four-wave mixing (FWM) in highly nonlinear fibers (HNLFs). This method can be applied for various modulation formats, including on-off keying and advanced multi-level modulation formats, without necessitating any changes of the hardware or software. Furthermore, it can expand the CD monitoring range beyond the limitation of Talbot effects and is insensitive to optical signal-to-noise ratio (OSNR) and polarization mode dispersion (PMD). These improvements are achieved by optimizing the profile of the PTF curve and utilizing a sweeping tunable dispersion compensator (TDC) in combination with an extremely simple digital signal processing (DSP) to find the zero residual dispersion point. Numerical simulations are then used to demonstrate the effectiveness of this method.

  20. Four-wave mixing using polarization grating induced thermal grating in liquids exhibiting circular dichroism

    SciTech Connect

    Nunes, J.A.; Tong, W.G.; Chandler, D.W.; Rahn, L.A.

    1995-04-01

    A novel four-wave mixing technique for the detection of circular dichroism in optically active liquid samples is demonstrated. When two cross-polarized laser beams are crossed at a small angle in a circular dichroic liquid a weak thermal grating is produced with a phase depending on the sign of the circular dichroism. The authors show that the polarization of one of the beams can be modified to allow coherent interference with an intensity-grating induced thermal grating. A probe beam scattering from the composite grating results in a signal that reveals the sign and magnitude of the circular dichroism. The use of this technique to optimize the signal-to-noise ratio in the presence of scattered light and laser intensity noise is discussed.

  1. Vibrational-coherence measurement of nonequilibrium quantum systems by four-wave mixing

    NASA Astrophysics Data System (ADS)

    Schubert, Alexander; Falvo, Cyril; Meier, Christoph

    2015-11-01

    We show theoretically that a quantum system in a nonequilibrium state interacting with a set of laser pulses in a four-wave-mixing setup leads to signal emission in directions opposite to the ones usually considered. When combined with a pump mechanism which sets a time origin for the nonequilibrium state creation, this particular optical response can be utilized to directly follow decoherence processes in real time. By varying the time delays within the probe sequence, signals in these unconventional directions can also be used to detect two-dimensional spectra determined by the dynamics of up to three-quantum coherences, revealing energetical anharmonicities and environmental influences. As a numerical example, these findings are demonstrated by considering a model of vibrational decoherence of carbon monoxide after photolysis from a hemeprotein.

  2. Experimental characterization of quantum correlated triple beams generated by cascaded four-wave mixing processes

    SciTech Connect

    Qin, Zhongzhong; Cao, Leiming; Jing, Jietai

    2015-05-25

    Quantum correlations and entanglement shared among multiple modes are fundamental ingredients of most continuous-variable quantum technologies. Recently, a method used to generate multiple quantum correlated beams using cascaded four-wave mixing (FWM) processes was theoretically proposed and experimentally realized by our group [Z. Qin et al., Phys. Rev. Lett. 113, 023602 (2014)]. Our study of triple-beam quantum correlation paves the way to showing the tripartite entanglement in our system. Our system also promises to find applications in quantum information and precision measurement such as the controlled quantum communications, the generation of multiple quantum correlated images, and the realization of a multiport nonlinear interferometer. For its applications, the degree of quantum correlation is a crucial figure of merit. In this letter, we experimentally study how various parameters, such as the cell temperatures, one-photon, and two-photon detunings, influence the degree of quantum correlation between the triple beams generated from the cascaded two-FWM configuration.

  3. Infrared pulse characterization using four-wave mixing inside a few cycle pulse filament in air

    SciTech Connect

    Marceau, Claude Thomas, Steven; Kassimi, Yacine; Gingras, Guillaume; Witzel, Bernd

    2014-02-03

    We demonstrate a four-wave mixing (FWM) technique to measure near- and mid-infrared (IR) laser pulse shapes in time domain. Few cycle 800 nm laser pulses were synchronized with the IR pulse and focused colinearly to generate a plasma filament in air. Second harmonic radiation around 400 nm was generated through FWM, with a yield proportional to the IR pulse intensity. Excellent signal to noise ratio was observed from 2.1 μm to 18 μm. With proper phase stabilization of the IR beam, this technique is a promising step toward direct electric field sensing of near-IR pulses in air.

  4. Phase quadrature discrimination based on three-pump four-wave mixing in nonlinear optical fibers.

    PubMed

    Baillot, Maxime; Gay, Mathilde; Peucheret, Christophe; Michel, Joindot; Chartier, Thierry

    2016-11-14

    We theoretically and experimentally study the principle of phase-sensitive frequency conversion in a highly-nonlinear fiber using three pump waves. This mechanism, originally demonstrated with four continuous-wave pumps and a signal wave, is based on four-wave mixing and enables to convert the two quadrature components of the signal to different frequencies. In this work, we derive a set of two simple equations to describe this mechanism and find analytic solutions. We show that only three pumps are required, instead of four as originally proposed. We give simple relations to determine the initial conditions for the power levels and the phases of the pumps. To validate this approach, we perform an experimental demonstration of the three-pump scheme and find excellent agreement with the theory.

  5. Optical bistability and four-wave mixing in a hybrid optomechanical system

    NASA Astrophysics Data System (ADS)

    Jiang, Lei; Yuan, Xiaorong; Cui, Yuanshun; Chen, Guibin; Zuo, Fen; Jiang, Cheng

    2017-10-01

    We explore theoretically the optical bistability and four-wave mixing (FWM) in a hybrid optomechanical system, where the mechanical resonator is simultaneously coupled to a cavity field and a two-level system (qubit). We can use a strong control field driving the cavity to control the bistable behavior of the steady-state photon number, phonon number, and the population inversion. The impact of qubit-resonator coupling strength on the bistable behavior is discussed. Furthermore, the two-level system can significantly modify the output fields of the cavity, leading to double optomechanically induced transparency (OMIT) and the enhancement of the FWM intensity. We find that the distance between the two peaks in the FWM spectrum can be controlled by the qubit-resonator coupling strength, and the peak value of the FWM intensity can be adjusted by the Rabi frequency of the control field.

  6. Rational design of metallic nanocavities for resonantly enhanced four-wave mixing.

    PubMed

    Almeida, Euclides; Prior, Yehiam

    2015-05-14

    Optimizing the shape of nanostructures and nano-antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four-Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell's equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near-infrared to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed.

  7. Quantitative degenerate four-wave mixing spectroscopy: Probes for molecular species

    SciTech Connect

    Farrow, R.; Rakestraw, D.; Paul, P.; Lucht, R.; Danehy, P.; Friedman-Hill, E.; Germann, G.

    1993-12-01

    Resonant degenerate four-wave mixing (DFWM) is currently the subject of intensive investigation as a sensitive diagnostic tool for molecular species. DFWM has the advantage of generating a coherent (beam-like) signal which results in null-background detection and provides excellent immunity to background-light interference. Since multiple one-photon resonances are involved in the signal generation process, the DFWM technique can allow sensitive detection of molecules via electronic, vibrational or rotational transitions. These properties combine to make DFWM a widely applicable diagnostic technique for the probing of molecular species. The authors are conducting fundamental and applied investigations of DFWM for quantitative measurements of trace species in reacting gases. During the past year, efforts have been focussed in two areas: (1) understanding the effects of collisional processes on the DFWM signal generation process, and (2) exploring the applicability of infrared DFWM to detect polyatomic molecules via rovibrational transitions.

  8. Optical cavity for enhanced parametric four-wave mixing in rubidium

    NASA Astrophysics Data System (ADS)

    Brekke, E.; Potier, S.

    2017-01-01

    We demonstrate the implementation of a ring cavity to enhance the efficiency of parametric four-wave mixing in rubidium. Using an input coupler with 95% reflectance, a finesse of 19.6$\\pm$0.5 is achieved with a rubidium cell inside. This increases the circulating intensity by a factor of 5.6$\\pm$0.5, and through two-photon excitation on the $5s_{1/2}\\rightarrow5d_{5/2}$ transition with a single excitation laser, up to 1.9$\\pm$0.3 mW of power at 420 nm is generated, 50 times what was previously generated with this scheme. The dependence of the output on Rb density and input power has been explored, suggesting the process may be approaching saturation. The blue output of the cavity also shows greatly improved spatial quality, combining to make this a promising source of 420 nm light for future experiments.

  9. Performance evaluation of four-wave mixing in a graphene-covered tapered fiber

    NASA Astrophysics Data System (ADS)

    Jin, Qiang; Lu, Jiamei; Li, Xibin; Yan, Qiang; Gao, Qianyu; Gao, Shiming

    2016-07-01

    Four-wave mixing in a monolayer graphene-covered tapered fiber is theoretically analyzed by taking into account the influence of the graphene layer on the light-field distribution. A figure-of-merit (FOM) coefficient, considering both the high nonlinearity and the heavy absorption, is redefined to evaluate nonlinear performance. The fiber diameter and length are optimized to acquire a higher FOM. Using such a graphene-covered tapered fiber with an optimal diameter of 0.736 μm, a maximum conversion efficiency of -38.07 dB is numerically obtained for the 1.55 μm pump when the graphene length is 34.4 μm and the peak pump power is 10 W. Moreover, a 3 dB bandwidth as broad as 430 nm can be realized in the 1.55 μm telecommunication band.

  10. Observation of the four wave mixing photonic band gap signal in electromagnetically induced grating.

    PubMed

    Ullah, Zakir; Wang, Zhiguo; Gao, Mengqin; Zhang, Dan; Zhang, Yiqi; Gao, Hong; Zhang, Yanpeng

    2014-12-01

    For the first time, we experimentally and theoretically research about the probe transmission signal (PTS), the reflected four wave mixing band gap signal(FWM BGS) and fluorescence signal (FLS) under the double dressing effect in an inverted Y-type four level system. FWM BGS results from photonic band gap structure. We demonstrate that the characteristics of PTS, FWM BGS and FLS can be controlled by power, phase and the frequency detuning of the dressing beams. It is observed in our experiment that FWM BGS switches from suppression to enhancement, corresponding to the switch from transmission enhancement to absorption enhancement in the PTS with changing the relative phase. We also observe the relation among the three signals, which satisfy the law of conservation of energy. Such scheme could have potential applications in optical diodes, amplifiers and quantum information processing.

  11. Methods and apparatus of entangled photon generation using four-wave mixing

    DOEpatents

    Camacho, Ryan

    2016-02-23

    A non-linear optical device is provided. The device comprises an optical disk or ring microresonator fabricated from a material that exhibits an optical nonlinearity able to produce degenerate four-wave mixing (FWM) in response to a pump beam having a pump frequency in a specified effective range. The microresonator is conformed to exhibit an angular group velocity minimum at a pump frequency within the specified effective range such that there is zero angular group velocity dispersion at the pump frequency. We refer to such a pump frequency as the "zero dispersion frequency". In embodiments, excitation of the resonator by a pump beam of sufficient intensity at the zero-dispersion frequency causes the resonator to emit a frequency comb of entangled photon pairs wherein the respective frequencies in each pair are symmetrically placed about the zero-dispersion frequency.

  12. Freely designable optical frequency conversion in Raman-resonant four-wave-mixing process

    PubMed Central

    Zheng, Jian; Katsuragawa, Masayuki

    2015-01-01

    Nonlinear optical processes are governed by the relative-phase relationships among the relevant electromagnetic fields in these processes. In this Report, we describe the physics of arbitrary manipulation of Raman-resonant four-wave-mixing process by artificial control of relative phases. As a typical example, we show freely designable optical-frequency conversions to extreme spectral regions, mid-infrared and vacuum-ultraviolet, with near-unity quantum efficiencies. Furthermore, we show that such optical-frequency conversions can be realized by using a surprisingly simple technology where transparent plates are placed in a nonlinear optical medium and their positions and thicknesses are adjusted precisely. In a numerical simulation assuming practically applicable parameters in detail, we demonstrate a single-frequency tunable laser that covers the whole vacuum-ultraviolet spectral range of 120 to 200 nm. PMID:25748023

  13. Scanning nonreciprocity spatial four-wave mixing process in moving photonic band gap

    NASA Astrophysics Data System (ADS)

    Wang, Hang; Zhang, Yunzhe; Li, Mingyue; Ma, Danmeng; Guo, Ji; Zhang, Dan; Zhang, Yanpeng

    2017-03-01

    We experimentally investigate the scanning nonreciprocity of four-wave mixing process induced by optical parametric amplification in moving photonic band gap, which is different from the propagation nonreciprocity in the optical diode. Meanwhile the frequency offset and the intensity difference are observed when we scan the frequency of the beams on two arm ramps of one round trip. Such scanning nonreciprocities can be controlled by changing the frequency detuning of the dressing beams. For the first time, we find that the intensity difference can cause the nonreciprocity in spatial image. In the nonreciprocity process, the focusing or defocusing is resulted from the feedback dressing self-phase modulation while shift and split is attributed to feedback dressing cross-phase modulation. Our study could have a potential application in the controllable optical diode.

  14. Intense terahertz-pulse generation by four-wave mixing process in induced gas plasma

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2015-08-01

    In this article, we have numerically investigated an intense terahertz (THz) pulses generation in gaseous plasma based on the third-order nonlinear effect, four-wave mixing rectification (FWMR). We have proposed that the fundamental fields and second-harmonic field of ultra-short pulse lasers are combined and focused into a very small gas chamber to induce a gaseous plasma, which intense THz pulse is produced. To understand the THz generation process, the first-order multiple-scale perturbation method (MSPM) has been utilized to derive a set of nonlinear coupled-mode equations for interacting fields such as two fundamental fields, a second-harmonic field, and a THz field. Then, we have simulate the intense THz-pulse generation by using split step-beam propagation method (SS-BPM) and calculated output THz intensities. Finally, the output THz intensities generated from induced air, nitrogen, and argon plasma have been compared.

  15. Rational design of metallic nanocavities for resonantly enhanced four-wave mixing

    PubMed Central

    Almeida, Euclides; Prior, Yehiam

    2015-01-01

    Optimizing the shape of nanostructures and nano-antennas for specific optical properties has evolved to be a very fruitful activity. With modern fabrication tools a large variety of possibilities is available for shaping both nanoparticles and nanocavities; in particular nanocavities in thin metal films have emerged as attractive candidates for new metamaterials and strong linear and nonlinear optical systems. Here we rationally design metallic nanocavities to boost their Four-Wave Mixing response by resonating the optical plasmonic resonances with the incoming and generated beams. The linear and nonlinear optical responses as well as the propagation of the electric fields inside the cavities are derived from the solution of Maxwell’s equations by using the 3D finite-differences time domain method. The observed conversion-efficiency of near-infrared to visible light equals or surpasses that of BBO of equivalent thickness. Implications to further optimization for efficient and broadband ultrathin nonlinear optical materials are discussed. PMID:25974175

  16. Experimental characterization of quantum correlated triple beams generated by cascaded four-wave mixing processes

    NASA Astrophysics Data System (ADS)

    Qin, Zhongzhong; Cao, Leiming; Jing, Jietai

    2015-05-01

    Quantum correlations and entanglement shared among multiple modes are fundamental ingredients of most continuous-variable quantum technologies. Recently, a method used to generate multiple quantum correlated beams using cascaded four-wave mixing (FWM) processes was theoretically proposed and experimentally realized by our group [Z. Qin et al., Phys. Rev. Lett. 113, 023602 (2014)]. Our study of triple-beam quantum correlation paves the way to showing the tripartite entanglement in our system. Our system also promises to find applications in quantum information and precision measurement such as the controlled quantum communications, the generation of multiple quantum correlated images, and the realization of a multiport nonlinear interferometer. For its applications, the degree of quantum correlation is a crucial figure of merit. In this letter, we experimentally study how various parameters, such as the cell temperatures, one-photon, and two-photon detunings, influence the degree of quantum correlation between the triple beams generated from the cascaded two-FWM configuration.

  17. Intermodal four-wave mixing in a higher-order-mode fiber.

    PubMed

    Cheng, Ji; Pedersen, Martin E V; Charan, Kriti; Wang, Ke; Xu, Chris; Grüner-Nielsen, Lars; Jakobsen, Dan

    2012-10-15

    We demonstrate a high-efficiency intermodal four-wave-mixing process in an all-fiber system, comprising a picosecond fiber laser and a high-order-mode (HOM) fiber. Two pump photons in the LP(01) mode of the fiber can generate an anti-Stokes photon in the LP(01) mode and a Stokes photon in the LP(02) mode. The wavelength dependent mode profiles of the HOM fiber produce significant spatial overlap between the modes involved. The anti-Stokes wave at 941 nm is generated with 20% conversion efficiency with input pulse energy of 20 nJ. The guidance of the anti-Stokes and Stokes waves in the HOM fiber enhances system stability.

  18. Competing four-wave mixing processes in dispersion oscillating telecom fiber.

    PubMed

    Finot, Christophe; Fatome, Julien; Sysoliatin, Alexej; Kosolapov, A; Wabnitz, Stefan

    2013-12-15

    We experimentally study the dynamics of the generation of multiple sidebands by means of a quasi-phase-matched four-wave mixing (FWM) process occurring in a dispersion-oscillating, highly nonlinear optical fiber. The fiber under test is pumped by a ns microchip laser operating in the normal average group-velocity dispersion regime and in the telecom C band. We reveal that the growth of higher-order sidebands is strongly influenced by the competition with cascade FWM between the pump and the first-order quasi-phase matched sidebands. The properties of these competing FWM processes are substantially affected when a partially coherent pump source is used, leading to a drastic reduction of the average power needed for sideband generation.

  19. Nonlinear processes responsible for nondegenerate four-wave mixing in quantum-dot optical amplifiers

    NASA Astrophysics Data System (ADS)

    Akiyama, Tomoyuki; Wada, Osamu; Kuwatsuka, Haruhiko; Simoyama, Takashi; Nakata, Yoshiaki; Mukai, Kohki; Sugawara, Mitsuru; Ishikawa, Hiroshi

    2000-09-01

    Wavelength conversion using nondegenerate four-wave mixing in quantum-dot optical amplifiers is investigated. From the detuning frequency dependence of χ(3), derived from the conversion efficiency, we consider that, within the range of detuning in the experiment, spectral-hole burning and carrier heating are responsible, and that their time constants, i.e., carrier relaxation time to the ground state and the phonon scattering time, are in the range of 60-140 and 200-400 fs, respectively. This indicates that the carrier supply to the ground level via relaxation from the higher levels is very fast and that a broad conversion bandwidth comparable to that of quantum-well devices is ensured.

  20. Plasmon excitation on flat graphene by s-polarized beams using four-wave mixing.

    PubMed

    Tao, Jin; Dong, Zhaogang; Yang, Joel K W; Wang, Qi Jie

    2015-03-23

    Graphene plasmons have received significant attention recently due to its attractive properties such as high spatial confinement and tunability. However, exciting plasmons on graphene effectively still remains a challenge owing to the large wave-vector mismatch between the optical beam in air and graphene plasmon. In this paper, we present a novel scheme capable of exciting graphene surface plasmons (GSPs) on a flat suspended graphene by using only s-polarized optical beams through four-wave mixing (FWM) process, where the GSPs fields were derived analytically based on the Green's function analysis, under the basis of momentum conservation. By incorporating the merits of nonlinear optics, the presented scheme avoids any patterning of either graphene or substrate. We believe that the proposed scheme potentially paves the way towards an efficient pure optical excitation, switching and modulation of GSPs for realizing graphene-based nano-photonic and optoelectronic integrated circuits.

  1. Nonlinear Sagnac interferometer based on the four-wave mixing process.

    PubMed

    Xin, Jun; Liu, Jinming; Jing, Jietai

    2017-01-23

    A new nonlinear Sagnac interferometer (NSI) is proposed by replacing the beam-splitter in the traditional Sagnac interferometer (TSI) with a four-wave mixing process. Such a NSI has better angular velocity sensitivity than the one of the TSI. The standard quantum limit can be beaten and the Heisenberg Limit can even be reached for the ideal case by the NSI. We study the effect of the losses on the angular velocity sensitivity of the NSI and find that the optimal angular velocity, where the best angular velocity sensitivity can be obtained, of the NSI may be dependent on the losses inside the interferometer. Such a NSI has its advantages compared with the TSI and may find its potential applications in quantum metrology.

  2. Filamentation assisted generation of tunable multicolored femtosecond sidebands based on cascaded four-wave mixing

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Liu, Jun; Li, Fangjia; Shen, Xiong; Li, Ruxin

    2015-05-01

    Tunable intense multicolored femtosecond sidebands are generated in a 0.1 mm-thick sapphire plate based on cascaded four-wave mixing (CFWM) by using a spectrally broadened pulse from filamentation in air and a 806 nm fundamental pulse from a Ti:sapphire laser amplifier. By using the filamentation to extend the spectrum of one incident pulse, the experimental setup is compact and inexpensive. Furthermore, the spectra of the sidebands can be conveniently tuned by varying the input power for the filamentation generation, and even the second-order frequency upconversion sideband can maintain its output power higher than 0.2 mW during the process of tuning. The generated sidebands are observed with a spectral range from 500 to 950 nm, and each spectrum has a full width half maximum (FWHM) bandwidth above 37 nm, which have potential applications in ultrafast spectroscopy and microscopy.

  3. Enhanced four-wave mixing in a hollow-core photonic-crystal fiber.

    PubMed

    Konorov, S O; Fedotov, A B; Zheltikov, A M

    2003-08-15

    Hollow-core photonic-crystal fibers are shown to substantially enhance four-wave mixing (FWM) of laser pulses in a gas filling the fiber core. Picosecond pulses of Nd:YAG fundamental radiation and its second harmonic are used to generate a signal at the frequency of the third harmonic by the FWM process 3omega = 2omega + 2omega - omega. The efficiency achieved for this process in a 9-cm-long, 13-microm-hollow-core-diameter photonic-crystal fiber, designed to simultaneously transmit a two-color pump and the FWM signal, is shown to be approximately 800 times higher than the maximum FWM efficiency attainable with the same laser pulses in the tight-focusing regime.

  4. Four-wave mixing in photonic crystal waveguides: slow light enhancement and limitations.

    PubMed

    Li, Juntao; O'Faolain, Liam; Rey, Isabella H; Krauss, Thomas F

    2011-02-28

    We demonstrate continuous wave four-wave mixing in silicon photonic crystal waveguides of 396 μm length with a group index of ng=30. The highest observed conversion efficiency is -24 dB for 90 mW coupled input pump power. The key question we address is whether the predicted fourth power dependence of the conversion efficiency on the slowdown factor (η≈S4) can indeed be observed in this system, and how the conversion efficiency depends on device length in the presence of propagation losses. We find that the expected dependencies hold as long as both realistic losses and the variation of mode shape with slowdown factor are taken into account. Having achieved a good agreement between a simple analytical model and the experiment, we also predict structures that can achieve the same conversion efficiency as already observed in nanowires for the same input power, yet for a device length that is 50 times shorter.

  5. Four-wave mixing in slow light engineered silicon photonic crystal waveguides.

    PubMed

    Monat, C; Ebnali-Heidari, M; Grillet, C; Corcoran, B; Eggleton, B J; White, T P; O'Faolain, L; Li, J; Krauss, T F

    2010-10-25

    We experimentally investigate four-wave mixing (FWM) in short (80 μm) dispersion-engineered slow light silicon photonic crystal waveguides. The pump, probe and idler signals all lie in a 14 nm wide low dispersion region with a near-constant group velocity of c/30. We measure an instantaneous conversion efficiency of up to -9dB between the idler and the continuous-wave probe, with 1W peak pump power and 6 nm pump-probe detuning. This conversion efficiency is found to be considerably higher (>10 × ) than that of a Si nanowire with a group velocity ten times larger. In addition, we estimate the FWM bandwidth to be at least that of the flat band slow light window. These results, supported by numerical simulations, emphasize the importance of engineering the dispersion of PhC waveguides to exploit the slow light enhancement of FWM efficiency, even for short device lengths.

  6. Broadband wavelength converter based on four-wave mixing in a highly nonlinear photonic crystal fiber.

    PubMed

    Zhang, Ailing; Demokan, M S

    2005-09-15

    We demonstrate a 10 Gbit/s nonreturn-to-zero wavelength converter based on four-wave mixing in a 20 m highly nonlinear photonic crystal fiber. The tunable wavelength conversion bandwidth (3 dB) is about 100 nm. The conversion efficiency is -16 dB when the pump power is 22.5 dBm. Phase modulation was not used to suppress the stimulated Brillouin scattering; thus the linewidth of the converted wavelength remained very narrow. The eye diagrams show that there is no additional noise during wavelength conversion. The measured power penalty at a 10(-9) bit-error-rate level is about 0.7 dB.

  7. Four-wave mixing in slow light photonic crystal waveguides with very high group index.

    PubMed

    Li, Juntao; O'Faolain, Liam; Krauss, Thomas F

    2012-07-30

    We report efficient four-wave mixing in dispersion engineered slow light silicon photonic crystal waveguides with a flat band group index of n(g) = 60. Using only 15 mW continuous wave coupled input power, we observe a conversion efficiency of -28 dB. This efficiency represents a 30 dB enhancement compared to a silicon nanowire of the same length. At higher powers, thermal redshifting due to linear absorption was found to detune the slow light regime preventing the expected improvement in efficiency. We then overcome this thermal limitation by using oxide-clad waveguides, which we demonstrate for group indices of ng = 30. Higher group indices may be achieved with oxide clad-waveguides, and we predict conversion efficiencies approaching -10 dB, which is equivalent to that already achieved in silicon nanowires but for a 50x shorter length.

  8. Four-wave mixing analysis on injection-locked quantum dot semiconductor lasers.

    PubMed

    Lin, Chih-Hao; Lin, Fan-Yi

    2013-09-09

    We derive a simplified rate equation model for the four-wave mixing (FWM) analysis on quantum dot (QD) semiconductor lasers subject to optical injection. The regenerative and the amplitude modulation spectra of the FWM signals with different intrinsic laser parameters and external injection conditions are investigated. By curve fitting the regenerative and the amplitude modulation spectra obtained experimentally, the intrinsic parameters of a commercial single-mode QD laser under different injection conditions are extracted. The linewidth enhancement factor α at different injection levels and detunings are shown, where a reduction of up to 39% from its free-running value is demonstrated. By increasing the injection strength, the α can be further reduced to minimized the chirp in optical communications.

  9. Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor

    NASA Astrophysics Data System (ADS)

    Gupta, Prasoon; Horrom, Travis; Anderson, Brian E.; Glasser, Ryan; Lett, Paul D.

    2016-02-01

    Four-wave mixing in atomic vapor allows for the generation of multi-spatial-mode states of light containing many pairs of two-mode entangled vacuum beams. This in principle can be used to send independent secure keys to multiple parties simultaneously using a single light source. In our experiment, we demonstrate this spatial multiplexing of information by selecting three independent pairs of entangled modes and performing continuous-variable measurements to verify the correlations between entangled partners. In this way, we generate three independent pairs of correlated random bit streams that could be used as secure keys. We then demonstrate a classical four-party secret sharing scheme as an example for how this spatially multiplexed source could be used.

  10. Highly efficient generation of broadband cascaded four-wave mixing products.

    PubMed

    Cerqueira S, Arismar; Boggio, J M Chavez; Rieznik, A A; Hernandez-Figueroa, H E; Fragnito, H L; Knight, J C

    2008-02-18

    We propose a novel way to efficiently generate broadband cascaded Four-Wave Mixing (FWM) products. It consists of launching two strong pump waves near the zero-dispersion wavelength of a very short (of order a few meters) optical fiber. Simulations based on Split Step Fourier Method (SSFM) and experimental data demonstrate the efficiency of our new approach. Multiple FWM products have been investigated by using conventional fibers and ultra-flattened dispersion photonic crystal fibers (UFD-PCFs). Measured results present bandwidths of 300 nm with up to 118 FWM products. We have also demonstrated a flat bandwidth of 110 nm covering the C and L bands, with a small variation of only 1.2 dB between the powers of FWM products, has been achieved using highly nonlinear fibers (HNLFs). The use of UFD-PCFs has been shown interesting for improving the multiple FWM efficiency and reducing the separation between the pump wavelengths.

  11. Photon statistics of pulse-pumped four-wave mixing in fiber with weak signal injection

    NASA Astrophysics Data System (ADS)

    Nan-Nan, Liu; Yu-Hong, Liu; Jia-Min, Li; Xiao-Ying, Li

    2016-07-01

    We study the photon statistics of pulse-pumped four-wave mixing in fibers with weak coherent signal injection by measuring the intensity correlation functions of individual signal and idler fields. The experimental results show that the intensity correlation function of individual signal (idler) field decreases with the intensity of signal injection. After applying narrow band filter in signal (idler) band, the value of decreases from 1.9 ± 0.02 (1.9 ± 0.02) to 1.03 ± 0.02 (1.05 ± 0.02) when the intensity of signal injection varies from 0 to 120 photons/pulse. The results indicate that the photon statistics changes from Bose-Einstein distribution to Poisson distribution. We calculate the intensity correlation functions by using the multi-mode theory of four-wave mixing in fibers. The theoretical curves well fit the experimental results. Our investigation will be useful for mitigating the crosstalk between quantum and classical channels in a dense wavelength division multiplexing network. Project supported by the National Natural Science Foundation of China (Grant No. 11527808), the State Key Development Program for Basic Research of China (Grant No. 2014CB340103), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120032110055), the Natural Science Foundation of Tianjin, China (Grant No. 14JCQNJC02300), the Program for Changjiang Scholars and Innovative Research Team in University, China, and the Program of Introducing Talents of Discipline to Universities, China (Grant No. B07014).

  12. Electric Field Measurements in Non-Equilibrium Electric Discharge Plasmas Using Picosecond Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.

    This dissertation presents the results of development of a picosecond four wave mixing technique and its use for electric field measurements in nanosecond pulse discharges. This technique is similar to coherent anti-Stokes Raman spectroscopy and is well suited for electric field measurements in high pressure plasmas with high spatial and temporal resolution. The results show that the signal intensity scales proportionally to the square of the electric field, the signal is emitted as a coherent beam, and is polarized parallel to the electric field vector, making possible electric field vector component measurements. The signal is generated when a collinear pair of pump and Stokes beams, which are generated in a stimulated Raman shifting cell (SRS), generate coherent excitation of molecules into a higher energy level, hydrogen for the present work. The coherent excitation mixes with a dipole moment induced by an external electric field. The mixing of these three "waves'" allows the molecules to radiate at their Raman frequency, producing a fourth, signal, wave which is proportional to the square of the electric field. The time resolution of this technique is limited by the coherence decay time of the molecules, which is a few hundred picoseconds.

  13. Interferometric coherence transfer modulations in triply vibrationally enhanced four-wave mixing.

    PubMed

    Rickard, Mark A; Pakoulev, Andrei V; Kornau, Kathryn; Mathew, Nathan A; Wright, John C

    2006-10-12

    Triply vibrationally enhanced (TRIVE) four-wave mixing (FWM) spectroscopy in a mixed frequency/time domain experiment contains new output coherences that isolate nonlinear pathways that involve coherence transfer. Coherence transfer occurs when a thermal bath induces coupling between two states so a quantum mechanical entanglement of a pair of quantum states evolves to entangle a new pair of quantum states. The FWM includes several equivalent coherence pathways that interfere and create a temporal modulation of the output coherence that is a signature of coherence transfer. The transfer shifts the output coherence frequency and isolates coherence transfer pathways from the stronger FWM processes that form the basis of coherent multidimensional spectroscopy. The use of coherence transfer offers the opportunity for another form of coherent multidimensional spectroscopy where cross-peaks appear because of the coherence transfer between quantum states. Since this approach is based on frequency domain methods, it requires only short-term phase coherence during the excitation process so the method is not constrained to accessing the quantum states lying within the excitation pulse bandwidth.

  14. Line-space description of resonant four-wave mixing: theory for isotropic molecular states.

    PubMed

    Kouzov, A; Radi, P

    2014-05-21

    Based on the quantum Liouville formalism, a theory of the two-color, triply resonant four-wave mixing is developed for molecules with isotropically oriented angular momenta. The approach allows to strictly incorporate the relaxation matrices Γ((r)) (r = 0, 1, 2) into the third-order susceptibility χ((3)) whose expression acquires therewith the form of a scalar product in the line space. Thanks to this representation, isolation of all resonance terms from χ((3)) becomes a routine task. Some of these terms correspond to the case when a molecule initially interacts with two pump photons of the same frequency. Such interactions give rise to the grating line-space vectors which have the same (zero) eigenfrequency. Due to this degeneracy, the latter are easily mixed by rotationally inelastic collisions which shows up in a state-resolved coherence transfer. The satellite signals induced thereby provide a great scope to study the state-to-state inelastic rates in situ by purely optical means. If the diagonal form of Γ is assumed, the satellites become forbidden and our results reduce to conventional expressions for the main resonances. Polarization configurations are designed for direct measurements of the population (r = 0), orientation (r = 1), and alignment (r = 2) contributions to χ((3)). Finally, depending on the photon-molecule interaction sequence, the resonance terms of χ((3)) are shown to be differently affected by velocity averaging, the effect which conspicuously manifests itself when Doppler broadening becomes paramount.

  15. The Effect of the Incident Relative Phase on the Four-Wave Mixing Field and the Electromagnetically Induced Transparency

    SciTech Connect

    Niu, Y.; Gong, S.

    2005-10-15

    In a {lambda}-type system employing a two-photon pump field, a four-wave mixing field can be generated simultaneously and, hence, a closed-loop system forms. We study theoretically the effect of the relative phase between the two incident fields on the generated four-wave mixing field and the electromagnetically induced transparency. It is found that the phase of the generated four-wave mixing field is the sum of the incident relative phase and a fixed phase that is irrelative to the incident relative phase. Hence, the total phase of the closed-loop system is independent of the incident relative phase. As a result, the incident relative phase has no effect on the electromagnetically induced transparency, which is different from the case of a {lambda}-type loop system closed by a third incident field.

  16. THz generation by two-color femtosecond filaments with complex polarization states: four-wave mixing versus photocurrent contributions

    NASA Astrophysics Data System (ADS)

    Fedorov, V. Yu; Koulouklidis, A. D.; Tzortzakis, S.

    2017-01-01

    Two-color filamenation in gases is known to produce intense and broadband THz radiation. There are two physical mechanisms responsible for the THz generation in this scheme: four-wave mixing and emission from the induced plasma currents. The case when the main and second harmonic are linearly polarized is well studied including the impact from each of the above mechanisms. However, for the cases when the two-color fields have complex polarization states the role of the four-wave mixing and plasma mechanisms in the formation of the THz polarization is still under-explored. Here we use both the four-wave mixing and photocurrent models in order to consider the THz generation by two-color fields with arbitrary polarizations. We show that under specific polarizations of the two-color field components it is possible to determine which of the mechanisms is responsible for the THz polarization formation.

  17. Polarization and probe delay effect on degenerate four wave mixing of pyrazine

    NASA Astrophysics Data System (ADS)

    Li, Hongzhi; Kong, Wei

    1997-09-01

    Degenerate four wave mixing (DFWM) in supersonically cooled pyrazine was investigated using different polarization combinations of the three input beams. A common feature of these spectra was the strong Q branch, stronger than the corresponding spectra for a single photon process. The ratios for all the rotational branches demonstrated strong dependence on the polarization combination. The YYXX combination showed similar intensities for the P and R branches, while the YXYX combination had a much stronger R branch. The Q branch, relative to the P branch, was the strongest for the YYYY combination. All experiments probed for the same electronic transition with the same Hönl-London factor; therefore the variation in the rotational branching ratios was solely an effect of the polarization combinations. This polarization dependence of DFWM can be traced back to the selectivity in the magnetic quantum number for this multiphoton process. Based on the theoretical framework by Williams et al. [J. Chem. Phys. 101, 1072 (1994)], these spectra were simulated successfully. The calculations and analysis of the experimental conditions revealed that among the twelve gratings included in the original theory, only three of them had observable contributions to the experimental spectra, i.e., the gratings formed through the ground-state molecules via the two forward beams. The other nine gratings either were washed out or decayed in the collision free environment (supersonic expansion) under an excitation pulse of 7 ns. This argument was further confirmed by another experiment using a time delay between the backward probe beam and the two forward beams. The spectra recorded with a 15 ns delay in the probe beam (longer than the pulse duration of each input beam) were similar to those without delays. These results implied that (1) the backward beam did not participate in the grating formation process even when it arrived at the interaction region simultaneously with the two forward

  18. Spectroscopy and wavelength conversion by four-wave mixing in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Hunziker, Guido H.

    The first part of this thesis is dedicated to the study of the physics of the four-wave mixing (FWM) optical non- linearity in semiconductor optical amplifiers (SOAS). We focus our attention on the polarization properties of FWM and spectroscopic measurements of ultrafast carrier dynamics in these amplifiers. The second part presents investigations of FWM applications in the context of high-speed optical communication systems. The detuning and polarization dependence of the third- order non-linear susceptibility is presented with a model based on the density matrix formalism. Experimental verifications of the model for the polarization properties of the four-wave mixing are presented using an alternating compressive and tensile strained multiquantum-well semiconductor optical amplifier. The polarization selection rules are then used for spectroscopic measurements of the carrier dynamics in quantum well SOAs. In particular, we present new techniques to measure the stimulated carrier lifetime, the inter quantum-well transport lifetime as well as the intrinsic escape and capture time constants for quantum wells. The capture lifetime is further studied in a separate experiment involving wavelength resolved spectroscopy. We then demonstrate that strongly saturated and long SOAs (1.5 mm) are very effective wide span wavelength converters. We present bit error rate measurements for 30 nm wavelength down-conversion and 15 nm wavelength up- conversion at 10 Gb/s. We also present an application of the polarization selection rules to generate a polarization independent conversion at 2.5 Gb/s. Then, we introduce two different configurations where we use a lasing optical amplifier with a fiber Bragg grating to enhance the conversion efficiency and simplify the converter design. In the first case, we used the laser mode as pump wave and in the second case the lasing mode is injection locked to the FWM signal generated within the cavity. Finally, we present a new paradigm to

  19. Nonlinear photonic crystal fiber with a structured multi-component glass core for four-wave mixing and supercontinuum generation.

    PubMed

    Tombelaine, Vincent; Labruyère, Alexis; Kobelke, Jens; Schuster, Kay; Reichel, Volker; Leproux, Philippe; Couderc, Vincent; Jamier, Raphaël; Bartelt, Hartmut

    2009-08-31

    We report about a new type of nonlinear photonic crystal fibers allowing broadband four-wave mixing and supercontinuum generation. The microstructured optical fiber has a structured core consisting of a rod of highly nonlinear glass material inserted in a silica tube. This particular structure enables four wave mixing processes with very large frequency detuning (>135 THz), which permitted the generation of a wide supercontinuum spectrum extending over 1650 nm after 2.15 m of propagation length. The comparison with results obtained from germanium-doped holey fibers confirms the important role of the rod material properties regarding nonlinear process and dispersion.

  20. Wideband tuning of four-wave mixing in solid-core liquid-filled photonic crystal fibers.

    PubMed

    Velázquez-Ibarra, Lorena; Díez, Antonio; Silvestre, Enrique; Andrés, Miguel V

    2016-06-01

    We present an experimental study of parametric four-wave mixing generation in photonic crystal fibers that have been infiltrated with ethanol. A silica photonic crystal fiber was designed to have the proper dispersion properties after ethanol infiltration for the generation of widely spaced four-wave mixing (FWM) bands under 1064 nm pumping. We demonstrate that the FWM bands can be tuned in a wide wavelength range through the thermo-optic effect. Band shifts of 175 and over 500 nm for the signal and idler bands, respectively, are reported. The reported results can be of interest in many applications, such as CARS microscopy.

  1. Quantum correlations by four-wave mixing in an atomic vapor in a nonamplifying regime: Quantum beam splitter for photons

    SciTech Connect

    Glorieux, Quentin; Guidoni, Luca; Guibal, Samuel; Likforman, Jean-Pierre; Coudreau, Thomas

    2011-11-15

    We study the generation of intensity quantum correlations using four-wave mixing in a rubidium vapor. The absence of cavities in these experiments allows to deal with several spatial modes simultaneously. In the standard amplifying configuration, we measure relative intensity squeezing up to 9.2 dB below the standard quantum limit. We also theoretically identify and experimentally demonstrate an original regime where, despite no overall amplification, quantum correlations are generated. In this regime, a four-wave mixing setup can play the role of a photonic beam splitter with nonclassical properties, that is, a device that splits a coherent state input into two quantum-correlated beams.

  2. Plasmonic nanofocused four-wave mixing for femtosecond near-field imaging

    NASA Astrophysics Data System (ADS)

    Kravtsov, Vasily; Ulbricht, Ronald; Atkin, Joanna M.; Raschke, Markus B.

    2016-05-01

    Femtosecond nonlinear optical imaging with nanoscale spatial resolution would provide access to coupled degrees of freedom and ultrafast response functions on the characteristic length scales of electronic and vibrational excitations. Although near-field microscopy provides the desired spatial resolution, the design of a broadband high-contrast nanoprobe for ultrafast temporal resolution is challenging due to the inherently weak nonlinear optical signals generated in subwavelength volumes. Here, we demonstrate broadband four-wave mixing with enhanced nonlinear frequency conversion efficiency at the apex of a nanometre conical tip. Far-field light is coupled through a grating at the shaft of the tip, generating plasmons that propagate to the apex while undergoing asymptotic compression and amplification, resulting in a nonlinear conversion efficiency of up to 1 × 10-5. We apply this nonlinear nanoprobe to image the few-femtosecond coherent dynamics of plasmonic hotspots on a nanostructured gold surface with spatial resolution of a few tens of nanometres. The approach can be generalized towards spatiotemporal imaging and control of coherent dynamics on the nanoscale, including the extension to multidimensional spectroscopy and imaging.

  3. A theory for non-degenerate four-wave mixing in doped graphene

    NASA Astrophysics Data System (ADS)

    Margulis, Vl. A.; Muryumin, E. E.; Gaiduk, E. A.

    2017-03-01

    We present a theoretical study of the nonlinear optical (NLO) response of doped graphene to two coherent laser beams, of frequencies ω1 and ω2, resulting in the generation of radiation at frequency ωσ = 2ω1 -ω2 . The two main ingredients of the developed theory are the interplay of interband and intraband electron motion, induced by the incident light waves, and the finite lifetime of excited electronic states, caused by electron scattering. Adopting a tight-binding approximation for the π-electronic band structure of graphene and the Genkin-Mednis formalism of the nonlinear conductivity theory of semiconductors, we calculate the third-order NLO susceptibility χ (3) (-ωσ ;ω1 ,ω1 , -ω2) responsible for the non-degenerate four-wave mixing process under consideration. Our calculations show the resonant enhancement of the |χ (3) | (up to a value of 2.8 ×10-7 esu) when the frequencies ω1 and ω2 of the input beams are mat"ched to provide a resonance for the output photon energy ℏωσ with an effective optical gap of 2EF in the π-electronic band structure of doped graphene (EF is the Fermi energy of charge carriers in the graphene, tunable by an external gate voltage). The results obtained may be of practical interest for generating mid-infrared radiation from doped graphene pumped with two near-infrared laser beams.

  4. Investigation of a four-wave mixing signal generated in fiber-delivered CARS microscopy.

    PubMed

    Jun, Chang Su; Kim, Byoung Yoon; Park, Ju Hyun; Lee, Jae Yong; Lee, Eun Seong; Yeom, Dong-Il

    2010-07-10

    We studied the nonlinear signal generated in the fiber at an anti-Stokes wavelength during the delivery of the picosecond (ps) pump and Stokes beams in coherent anti-Stokes Raman scattering (CARS) microscopy. A small non-phase-matched four-wave mixing (FWM) signal was prevalently observed in the fiber at the power level where other nonlinear processes, including self-phase modulation and cross-phase modulation, were well suppressed. We analyzed the features of the FWM signal generation by varying the location of temporal overlap between two input pulses in the fiber to compare this to the CARS signal generated in the sample. Numerical modeling based on the nonlinear Schrödinger equation was also conducted and clearly explains the results in the experiment. In addition, we experimentally verified the interferometric feature of this FWM signal with the CARS signal by employing a phase-shifting unit, which potentially suggests the use of the FWM signal as a local oscillator for the interferometric CARS system.

  5. Dressed Gain from the Parametrically Amplified Four-Wave Mixing Process in an Atomic Vapor

    NASA Astrophysics Data System (ADS)

    Zhang, Zhaoyang; Wen, Feng; Che, Junling; Zhang, Dan; Li, Changbiao; Zhang, Yanpeng; Xiao, Min

    2015-10-01

    With a forward cone emitting from the strong pump laser in a thermal rubidium atomic vapor, we investigate the non-degenerate parametrically amplified four-wave mixing (PA-FWM) process with dressing effects in a three-level “double-Λ” configuration both theoretically and experimentally. By seeding a weak probe field into the Stokes or anti-Stokes channel of the FWM, the gain processes are generated in the bright twin beams which are called conjugate and probe beams, respectively. However, the strong dressing effect of the pump beam will dramatically affect the gain factors both in the probe and conjugate channels, and can inevitably impose an influence on the quantum effects such as entangled degree and the quantum noise reduction between the two channels. We systematically investigate the intensity evolution of the dressed gain processes by manipulating the atomic density, the Rabi frequency and the frequency detuning. Such dressing effects are also visually evidenced by the observation of Autler-Townes splitting of the gain peaks. The investigation can contribute to the development of quantum information processing and quantum communications.

  6. Combined third-harmonic generation and four-wave mixing microscopy of tissues and embryos.

    PubMed

    Mahou, Pierre; Olivier, Nicolas; Labroille, Guillaume; Duloquin, Louise; Sintes, Jean-Marc; Peyriéras, Nadine; Legouis, Renaud; Débarre, Delphine; Beaurepaire, Emmanuel

    2011-10-01

    Nonlinear microscopy can be used to probe the intrinsic optical properties of biological tissues. Using femtosecond pulses, third-harmonic generation (THG) and four-wave mixing (FWM) signals can be efficiently produced and detected simultaneously. Both signals probe a similar parameter, i.e. the real part of the third-order nonlinear susceptibility χ((3)). However THG and FWM images result from different phase matching conditions and provide complementary information. We analyze this complementarity using calculations, z-scan measurements on water and oils, and THG-FWM imaging of cell divisions in live zebrafish embryos. The two signals exhibit different sensitivity to sample size and clustering in the half-wavelength regime. Far from resonance, THG images reveal spatial variations |Δχ((3))(-3ω;ω,ω,ω)| with remarkable sensitivity while FWM directly reflects the distribution of χ((3))(-2ω(1) + ω(2);ω(1), -ω(2), ω(1)). We show that FWM images provide χ((3)) maps useful for proper interpretation of cellular THG signals, and that combined imaging carries additional structural information. Finally we present simultaneous imaging of intrinsic THG, FWM, second-harmonic (SHG) and two-photon-excited fluorescence (2PEF) signals in live Caenorhabditis elegans worms illustrating the information provided by multimodal nonlinear imaging of unstained tissue.

  7. Nondegenerate Four-Wave Mixing in Gold Nanocomposites Formed by Ion Implantation

    SciTech Connect

    Saonov, V.P.; Zhu, J.G.; Lepeshkin, N.N.; Armstrong, R.L.; Shalaev, V.M.; Ying, Z.C.; White, C.W.; Zuhr, R.A.

    1999-07-01

    Nondegenerate four-wave mixing technique has been used to investigate the third-order nonlinear susceptibility for nanocomposite material with Au nanocrystals formed inside a SiO{sub 2} glass matrix. High concentrations of encapsulated Au nanocrystals are formed by implantation of Au ions into fused silica glass substrates and thermal annealing. The size distribution and the depth profiles of the Au nanoparticles can be controlled by the implantation dose, energy and annealing temperatures. The high value of the third-order susceptibility - (0.26--1.3)x10{sup -7} esu was found in the range of the frequency detunings near the surface plasmon resonance. Two characteristic relaxation times, 0.66 ps and 5.3 ps, have been extracted from the detuning curve of the third-order susceptibility as the probe-beam frequency changes and the pump-beam frequency fixed at the plasmon resonance. The first relaxation time was attributed to electron-phonon relaxation, and the second to thermal diffusion to the host medium. The efficient nondegenerate conversion is attractive for optical processing.

  8. Phase-sensitive cascaded four-wave-mixing processes for generating three quantum correlated beams

    NASA Astrophysics Data System (ADS)

    Wang, Li; Wang, Hailong; Li, Sijin; Wang, Yaxian; Jing, Jietai

    2017-01-01

    Theoretical studies and experimental implementations of quantum correlation are the important contents of continuous variables quantum optics and quantum information science. There are various systems for the study of quantum correlation. Here, we study an experimental scheme for generating three quantum correlated beams based on phase-sensitive cascaded four-wave-mixing (FWM) processes in rubidium vapor. Quantum correlation including intensity difference or sum squeezing, two other combinatorial squeezing, and quantum entanglement among the three output light fields are theoretically analyzed in this paper. Also, the comparison of the quantum correlations have been made between the phase-sensitive cascaded FWM processes and the phase-insensitive cascaded FWM processes. By changing the phases and intensities of the input beams, it is interesting to find that the maximum degrees of various combinatorial squeezing are equal when the two FWM processes share a common intensity gain. When the common intensity gain of the two FWM processes changes, the maximum degrees of different combinatorial squeezing will be synchronously controlled. At last we discuss the genuine tripartite entanglement and steering in our phase-sensitive cascaded scheme, and compare them with the cases of the phase-insensitive cascaded scheme.

  9. Experimental setups for FEL-based four-wave mixing experiments at FERMI

    SciTech Connect

    Bencivenga, Filippo; Zangrando, Marco; Svetina, Cristian; Abrami, Alessandro; Battistoni, Andrea; Borghes, Roberto; Capotondi, Flavio; Cucini, Riccardo; Dallari, Francesco; Danailov, Miltcho; Demidovich, Alexander; Fava, Claudio; Gaio, Giulio; Gerusina, Simone; Gessini, Alessandro; Giacuzzo, Fabio; Gobessi, Riccardo; Godnig, Roberto; Grisonich, Riccardo; Kiskinova, Maya; Kurdi, Gabor; Loda, Giorgio; Lonza, Marco; Mahne, Nicola; Manfredda, Michele; Mincigrucci, Riccardo; Pangon, Gianpiero; Parisse, Pietro; Passuello, Roberto; Pedersoli, Emanuele; Pivetta, Lorenzo; Prica, Milan; Principi, Emiliano; Rago, Ilaria; Raimondi, Lorenzo; Sauro, Roberto; Scarcia, Martin; Sigalotti, Paolo; Zaccaria, Maurizio; Masciovecchio, Claudio

    2016-01-01

    The recent advent of free-electron laser (FEL) sources is driving the scientific community to extend table-top laser research to shorter wavelengths adding elemental selectivity and chemical state specificity. Both a compact setup (mini-TIMER) and a separate instrument (EIS-TIMER) dedicated to four-wave-mixing (FWM) experiments has been designed and constructed, to be operated as a branch of the Elastic and Inelastic Scattering beamline: EIS. The FWM experiments that are planned at EIS-TIMER are based on the transient grating approach, where two crossed FEL pulses create a controlled modulation of the sample excitations while a third time-delayed pulse is used to monitor the dynamics of the excited state. This manuscript describes such experimental facilities, showing the preliminary results of the commissioning of the EIS-TIMER beamline, and discusses original experimental strategies being developed to study the dynamics of matter at the fs–nm time–length scales. In the near future such experimental tools will allow more sophisticated FEL-based FWM applications, that also include the use of multiple and multi-color FEL pulses.

  10. Optical negative refraction by four-wave mixing in thin metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Palomba, Stefano; Zhang, Shuang; Park, Yongshik; Bartal, Guy; Yin, Xiaobo; Zhang, Xiang

    2012-01-01

    The law of refraction first derived by Snellius and later introduced as the Huygens-Fermat principle, states that the incidence and refracted angles of a light wave at the interface of two different materials are related to the ratio of the refractive indices in each medium. Whereas all natural materials have a positive refractive index and therefore exhibit refraction in the positive direction, artificially engineered negative index metamaterials have been shown capable of bending light waves negatively. Such a negative refractive index is the key to achieving a perfect lens that is capable of imaging well below the diffraction limit. However, negative index metamaterials are typically lossy, narrow band, and require complicated fabrication processes. Recently, an alternative approach to obtain negative refraction from a very thin nonlinear film has been proposed and experimentally demonstrated in the microwave region. However, such approaches use phase conjugation, which makes optical implementations difficult. Here, we report a simple but different scheme to demonstrate experimentally nonlinear negative refraction at optical frequencies using four-wave mixing in nanostructured metal films. The refractive index can be designed at will by simply tuning the wavelengths of the interacting waves, which could have potential impact on many important applications, such as superlens imaging.

  11. Optical imaging through turbid media with a degenerate four wave mixing correlation time gate

    SciTech Connect

    Sappey, A.D. )

    1994-12-20

    A novel method for detection of ballistic light and rejection of unwanted diffusive light to image structures inside highly scattering media is demonstrated. Degenerate four wave mixing (DFWM) of a doubled YAG laser in Rhodamine 6G is used to provide an ultrafast correlation time gate to discriminate against light that has undergone multiple scattering and therefore lost memory of the structures inside the scattering medium. We present preliminary results that determine the nature of the DFWM grating, confirm the coherence time of the laser, prove the phase-conjugate nature of the signal beam, and determine the dependence of the signal (reflectivity) on dye concentration and laser intensity. Finally, we have obtained images of a test cross-hair pattern through highly turbid suspensions of whole milk in water that are opaque to the naked eye. These imaging experiments demonstrate the utility of DFWM for imaging through turbid media. Based on our results, the use of DFWM as an ultrafast time gate for the detection of ballistic light in optical mammography appears to hold great promise for improving the current state of the art.

  12. Light storage based on four-wave mixing and electromagnetically induced transparency in cold atoms

    NASA Astrophysics Data System (ADS)

    Wu, Jinghui; Liu, Yang; Ding, Dong-Sheng; Zhou, Zhi-Yuan; Shi, Bao-Sen; Guo, Guang-Can

    2013-01-01

    We performed an experiment to observe the storage of an input probe field and an idler field generated through an off-axis four-wave mixing (FWM) process via a double-Λ configuration in a cold atomic ensemble. We analyzed the underlying physics in detail and found that the retrieved idler field came from two parts if there was no single-photon detuning for the pump pulse: Part 1 was from the collective atomic spin (the input probe field, the coupling field, and the pump field combined to generate the idler field through FWM; then the idler was stored through electromagnetically induced transparency). Part 2 was from the generated new FWM process during the retrieval process (the retrieved probe field, the coupling field, and the pump field combined to generate a new FWM signal). If there was single-photon detuning for the pump pulse, then the retrieved idler was mainly from part 2. The retrieved two fields exhibited damped oscillations with the same oscillatory period when a homogeneous external magnetic field was applied, which was caused by the Larmor spin precession. We also experimentally realized the storage and retrieval of an image of light using FWM, in which an image was added into the input signal. After the storage, the retrieved idler beams and input signal carried the same image. This image storage technique holds promise for applications in image processing, remote sensing, and quantum communication.

  13. Low-frequency four-wave mixing spectroscopy of biomolecules in aqueous solutions

    SciTech Connect

    Bunkin, Aleksei F; Pershin, S M

    2011-01-24

    Four-wave mixing (FWM) spectroscopy is used to detect the rotational resonances of H{sub 2}O and H{sub 2}O{sub 2} molecules in DNA and denatured DNA aqueous solutions in the range {+-}10 cm{sup -1} with a spectral resolution of 3 GHz. It is found that the resonance contribution of the rotational transitions of these molecules increases significantly in solutions rather than in distilled water. This fact is interpreted as a manifestation of specific properties of a hydration layer at DNA-water and denatured DNA-water interfaces. Analysis of the FWM spectra shows that the concentration of H{sub 2}O{sub 2} molecules in the hydration layer of the DNA solution increases by a factor of 3 after denaturation. The FWM spectra of aqueous solutions of {alpha}-chymotrypsin protein are obtained in the range {+-}7cm{sup -1} at the protein concentrations between 0 and 20 mg cm{sup -3}. It is found that the hypersound velocity in the protein aqueous solution, measured by the shift of Brillouin components in the scattering spectrum, obeys a cubic dependence on the protein concentration and reaches a value of about 3000 m s{sup -1} at 20 mg cm{sup -3}. (application of lasers and laser-optical methods in life sciences)

  14. Four-wave mixing and optical phase conjugation in vertical-cavity surface-emitting devices

    NASA Astrophysics Data System (ADS)

    Vansuch, Gregory Joseph

    1997-08-01

    Four-wave mixing (FWM), a nonlinear optical process, was investigated in resonant cavity light emitting diodes (RCLEDs) and vertical cavity surface emitting lasers (VCSELs) below lasing threshold. These semiconductor photonic devices consisted of an optical gain region of quantum wells sandwiched between two distributed Bragg reflector (DBR) mirrors. Pump and probe lasers were injected into the devices to generate FWM. The dependence of FWM on bias current, pump laser power, and spectral and spatial separation between pump and probe lasers was investigated experimentally. A computer model of FWM based on the wave and carrier density equations was developed and agreed well with experimental results. Conjugate reflectivities of 1.0 were obtained in the VCSEL when bias current was below threshold but above transparency. Reasonable conjugate reflectivities were obtained for pump-probe detunings up to 2 GHz in both devices. Noncollinear FWM was performed for the first time in VCSELs or RCLEDs at angles up to 10o. Both experiment and model showed the possibility of generating a strong reflected conjugate signal while minimizing the reflected pump signal. The noncollinear FWM demonstrated the possibility of phase front conjugation for correcting aberrated signals in vertical cavity devices.

  15. Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.

    PubMed

    Jiang, Qichang; Zhang, Yan; Wang, Dan; Ahrens, Sven; Zhang, Junxiang; Zhu, Shiyao

    2016-10-17

    We report the experimental manipulation of the group velocities of reflected and transmitted light pulses in a degenerate two-level atomic system driven by a standing wave, which is created by two counter-propagating light beams of equal frequencies but variable amplitudes. It is shown that the light pulse is reflected with superluminal group velocity while the transmitted pulse propagates from subluminal to superluminal velocities via changing the power of the backward coupling field. We find that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms. The theoretical discussion shows that the anomalous dispersion associated with a resonant absorption dip within the gain peak due to four-wave mixing leads to the superluminal reflection, while the varying dispersion from normal to anomalous at transparency, transparency within absorption, and electromagnetically induced absorption windows leads to the subluminal to superluminal transmission.

  16. Self-seeded four-wave mixing cascades with low power consumption

    NASA Astrophysics Data System (ADS)

    Cholan, N. A.; Al-Mansoori, M. H.; Noor, A. S. M.; Ismail, A.; Mahdi, M. A.

    2014-10-01

    The efficient generation of self-seeded four-wave mixing (FWM) cascades utilizing a double pass technique is demonstrated. To prove the efficiency of this technique, FWM cascades with a double-pass scheme are compared to their counterpart with a single-pass scheme. Experimental results indicate that the double-pass scheme consumes less power than the single-pass scheme. For the generation of ten spectral lines, the double-pass scheme requires an erbium-doped fiber amplifier (EDFA) output power of 114.02 mW, representing a 69% improvement over the single-pass scheme, which demands an EDFA output power of 366.32 mW. This is attributed to the use of the first-pass FWM cascades as seeds in the double-pass scheme, in contrast to two intracavity pumps as seeds in the single-pass scheme. The proposed scheme is not only free from external laser sources and phase modulators but also needs low power for operation, leading to the double-pass scheme being more cost effective than the single-pass scheme.

  17. Nondegenerate four-wave mixing in a dual mode injection locked quantum dot laser

    NASA Astrophysics Data System (ADS)

    Grillot, Frédéric; Wang, Cheng; Aldaya-Garde, Ivan A.; Gosset, Christophe; Batte, Thomas; Decerle, Etienne; Even, Jacky

    2014-03-01

    Nondegenerate four-wave mixing (NDFWM) in semiconductor gain media is a promising source for wavelength conversion in the wavelength division multiplexed (WDM) systems and for fiber dispersion compensation in long distance fiber links. In contrast to bulk and quantum well (QW) semiconductors, the quantum dot (QD) gain medium is favorable for enhancing the performance of the FWM because of the wide gain spectrum, large nonlinear effect as well as ultrafast carrier dynamics. Especially, the destructive interference can be eliminated due to the reduced linewidth enhancement factor (LEF) for obtaining high efficiency in the wavelength up-conversion. This work reports the NDFWM generation in a dual-mode injection-locked QD Fabry-Perot (FP) laser. The device has a wide gain spectrum with a full width at half maximum of 81 nm, and a peak net modal gain of 14.4 cm-1. The laser exhibits two lasing peaks induced by Rabi oscillation, which provides the possibility for efficient FWM generation. Employing the dual-mode injection-locking scheme, an efficient NDFWM is achieved up to a detuning range of 1.7 THz with a weak injection ratio of 0.44. The highest measured values for both the normalized conversion efficiency (NCE) and the side-mode suppression ratio (SMSR) with respect to the converted signal respectively are -17 dB and 20.3 dB at the detuning 110 GHz.

  18. Four-wave mixing in Bose-Einstein condensate systems with multiple spin states

    SciTech Connect

    Burke, J.P. Jr.; Julienne, P. S.; Williams, C.J.; Band, Y.B.; Trippenbach, M.

    2004-09-01

    We calculate the four-wave mixing (FWM) in a Bose-Einstein condensate system having multiple spin wave packets that are initially overlapping in physical space, but have nonvanishing relative momentum that causes them to recede from one another. Three receding condensate atom wave packets can result in production of a fourth wave packet by the process of FWM due to atom-atom interactions. We consider cases where the four final wave packets are composed of one, two, three, and four different internal spin components. FWM with one or two-spin state wave packets is much stronger than three- or four-spin state FWM, wherein two of the coherent moving Bose-Einstein condensate wave packets form a spin-polarization grating that rotates the spin projection of the third wave into that of the fourth diffracted wave (as opposed to the one- or two-spin state case where a regular density grating is responsible for the diffraction). Calculations of FWM for {sup 87}Rb and {sup 23}Na condensate systems are presented.

  19. Theoretical Analysis of the Resonance Four-Wave Mixing Amplitudes: a Fully Non-Degenerate Case.

    NASA Astrophysics Data System (ADS)

    Kouzov, Alexander

    2015-06-01

    Degenerate (one-color) and two-color variants of the resonant four-wave mixing (RFWM) have developed into a sensitive and nonintrusive spectroscopic tool to study molecules in different gaseous environments. Yet, the fully non-degenerate (four-color, 4C) RFWM was scrutinized and implemented only for the Coherent AntiStokes Raman Scattering (CARS) excitation scheme. Here, by using the line-space approach, we analyze other 4C-RFWM schemes potentially interesting for the efficient up- and down-frequency conversion as well as for studies of molecular states. Decoupled expressions of the 4C-RFWM amplitudes are derived which allows to predict their polarization dependence. B. Attal-Trétout, P. Berlemont, and J. P. Taran, Mol. Phys. 70, 1 (1990). J.P. Kuehner, S.V. Naik, W.D. Kulatilaka, N. Chai, N.M. Laurendeau, R.P. Lucht, M.O. Scully, S. Roy, A.K. Patnaik, and J.R. Gord, J. Chem. Phys. 128, 174308 (2008). A. Kouzov and P. Radi, J. Chem. Phys. 140, 194302 (2014).

  20. Four-wave-mixing experiments and beyond: the TIMER/mini-TIMER setups at FERMI

    NASA Astrophysics Data System (ADS)

    Foglia, Laura; Bencivenga, Filippo; Mincigrucci, Riccardo; Simoncig, Alberto; Calvi, Andrea; Cucini, Riccardo; Principi, Emiliano; Zangrando, Marco; Mahne, Nicola; Manfredda, Michele; Raimondi, Lorenzo; Pedersoli, Emanuele; Capotondi, Flavio; Kiskinova, Maya; Masciovecchio, Claudio

    2017-05-01

    The development of free electron laser (FEL) sources, which provide extreme ultraviolet (XUV) and soft x-ray radiation of unprecedented coherence and almost transform-limited pulse structure, has opened up the realm of XUV/x-ray non-linear optics. In particular, XUV four-wave-mixing (XFWM) experiments may allow, e.g., to probe correlations among low-energy excitations and core states, and to access the "mesoscopic" wavevector range (0.1-1 nm-1), inaccessible so far and fundamental to investigate nanostructures and disordered systems. In this manuscript we report on the latest advances and future developments of the TIMER setup at FERMI (Elettra, Italy), specifically conceived for XFWM experiments. In particular, we discuss the improvements on the XUV-probe and on the pump transport. Moreover, TIMER and mini-TIMER (a test setup available at the DiProI end station) are also suitable for time-resolved second order nonlinear experiments, which are intrinsically surface sensitive due to symmetry restrictions. We hereby discuss the foreseen extension to the XUV of interface specific probing of electronic processes, for example charge and energy transfer, with chemical specificity.

  1. Degenerate four-wave mixing and phase conjugation in a collisional plasma

    SciTech Connect

    Federici, J.F.; Mansfield, D.K.

    1986-06-01

    Although degenerate four-wave mixing (DFWM) has many practical applications in the visible regime, no successful attempt has been made to study or demonstrate DFWM for wavelengths longer than 10..mu..m. Recently, Steel and Lam established plasma as a viable DFWM and phase conjugation (PC) medium for infrared, far-infrared, and microwaves. However, their analysis is incomplete since collisional effects were not included. Using a fluid description, our results demonstrate that when collisional absorption is small and the collisional mean-free path is shorter than the nonlinear density grating scale length, collisional heating generates a thermal force which substantially enhances the phase conjugate reflectivity. When the collisional attenuation length becomes comparable to the length of the plasma, the dominant effect is collisional absorption of the pump waves. Numerical estimates of the phase conjugate reflectivity indicate that for modest power levels, gains greater than or equal to1 are possible in the submillimeter to centimeter wavelength range. This suggests that a plasma is a viable PC medium at those long wavelengths. In addition, doubly DFWM is discussed.

  2. Phase-locking and Pulse Generation in Multi-Frequency Brillouin Oscillator via Four Wave Mixing

    NASA Astrophysics Data System (ADS)

    Büttner, Thomas F. S.; Kabakova, Irina V.; Hudson, Darren D.; Pant, Ravi; Poulton, Christopher G.; Judge, Alexander C.; Eggleton, Benjamin J.

    2014-05-01

    There is an increasing demand for pulsed all-fibre lasers with gigahertz repetition rates for applications in telecommunications and metrology. The repetition rate of conventional passively mode-locked fibre lasers is fundamentally linked to the laser cavity length and is therefore typically ~10-100 MHz, which is orders of magnitude lower than required. Cascading stimulated Brillouin scattering (SBS) in nonlinear resonators, however, enables the formation of Brillouin frequency combs (BFCs) with GHz line spacing, which is determined by the acoustic properties of the medium and is independent of the resonator length. Phase-locking of such combs therefore holds a promise to achieve gigahertz repetition rate lasers. The interplay of SBS and Kerr-nonlinear four-wave mixing (FWM) in nonlinear resonators has been previously investigated, yet the phase relationship of the waves has not been considered. Here, we present for the first time experimental and numerical results that demonstrate phase-locking of BFCs generated in a nonlinear waveguide cavity. Using real-time measurements we demonstrate stable 40 ps pulse trains with 8 GHz repetition rate based on a chalcogenide fibre cavity, without the aid of any additional phase-locking element. Detailed numerical modelling, which is in agreement with the experimental results, highlight the essential role of FWM in phase-locking of the BFC.

  3. Dressed Gain from the Parametrically Amplified Four-Wave Mixing Process in an Atomic Vapor

    PubMed Central

    Zhang, Zhaoyang; Wen, Feng; Che, Junling; Zhang, Dan; Li, Changbiao; Zhang, Yanpeng; Xiao, Min

    2015-01-01

    With a forward cone emitting from the strong pump laser in a thermal rubidium atomic vapor, we investigate the non-degenerate parametrically amplified four-wave mixing (PA-FWM) process with dressing effects in a three-level “double-Λ” configuration both theoretically and experimentally. By seeding a weak probe field into the Stokes or anti-Stokes channel of the FWM, the gain processes are generated in the bright twin beams which are called conjugate and probe beams, respectively. However, the strong dressing effect of the pump beam will dramatically affect the gain factors both in the probe and conjugate channels, and can inevitably impose an influence on the quantum effects such as entangled degree and the quantum noise reduction between the two channels. We systematically investigate the intensity evolution of the dressed gain processes by manipulating the atomic density, the Rabi frequency and the frequency detuning. Such dressing effects are also visually evidenced by the observation of Autler-Townes splitting of the gain peaks. The investigation can contribute to the development of quantum information processing and quantum communications. PMID:26463588

  4. Quantum optical devices based on four-wave mixing in hot rubidium vapor

    NASA Astrophysics Data System (ADS)

    Fang, YaMi; Qin, ZhongZhong; Wang, HaiLong; Cao, LeiMing; Xin, Jun; Feng, JingLiang; Zhang, WeiPing; Jing, JieTai

    2015-06-01

    In this paper, we briefly review the recent experimental progresses in quantum optics based on four-wave mixing (FWM) processes in hot rubidium vapor, particularly our two recent experiments in quantum information. We have experimentally produced strong quantum correlations between three bright beams generated by two cascaded FWM processes. The intensity difference squeezing with the cascaded system is enhanced to (-7.0±0.1)dB from the (-5.5±0.1)dB/(-4.5±0.1)dB with only one FWM process. Also, this system can be easily extended to multiple modes using multiple FWM processes. Besides, we have also successfully realized a cascade all-optical transistor (AOT), which is driven by a very weak light beam about 800 photons in total. The required probe power for achieving a switching efficiency of 50% can be as low as 180 pW, and it can manipulate a light beam with power of 5.0×106 times more, which proves the cascade of the AOT. Both experiments may find wide applications in quantum information and optical communication.

  5. Theory of pulsed four-wave mixing in one-dimensional silicon photonic crystal slab waveguides

    NASA Astrophysics Data System (ADS)

    Lavdas, Spyros; Panoiu, Nicolae C.

    2016-03-01

    We present a comprehensive theoretical analysis and computational study of four-wave mixing (FWM) of optical pulses co-propagating in one-dimensional silicon photonic crystal waveguides (Si-PhCWGs). Our theoretical analysis describes a very general setup of the interacting optical pulses, namely we consider nondegenerate FWM in a configuration in which at each frequency there exists a superposition of guiding modes. We incorporate in our theoretical model all relevant linear optical effects, including waveguide loss, free-carrier (FC) dispersion and FC absorption, nonlinear optical effects such as self- and cross-phase modulation (SPM, XPM), two-photon absorption (TPA), and cross-absorption modulation (XAM), as well as the coupled dynamics of free-carriers FCs and optical field. In particular, our theoretical analysis based on the coupled-mode theory provides rigorously derived formulas for linear dispersion coefficients of the guiding modes, linear coupling coefficients between these modes, as well as the nonlinear waveguide coefficients describing SPM, XPM, TPA, XAM, and FWM. In addition, our theoretical analysis and numerical simulations reveal key differences between the characteristics of FWM in the slow- and fast-light regimes, which could potentially have important implications to the design of ultracompact active photonic devices.

  6. Fiber-based source for multiplex-CARS microscopy based on degenerate four-wave mixing.

    PubMed

    Gottschall, Thomas; Baumgartl, Martin; Sagnier, Aude; Rothhardt, Jan; Jauregui, Cesar; Limpert, Jens; Tünnermann, Andreas

    2012-05-21

    We present a fiber-based laser source for multiplex coherent anti-Stokes Raman scattering (CARS) microscopy. This source is very compact and potentially alignment-free. The corresponding pump and Stokes pulses for the CARS process are generated by degenerate four-wave mixing (FWM) in photonic-crystal fibers. In addition, an ytterbium-doped fiber laser emitting spectrally narrow 100 ps pulses at 1035 nm wavelength serves as pump for the FWM frequency conversion. The FWM process delivers narrow-band pulses at 648 nm and drives a continuum-like spectrum ranging from 700 to 820 nm. With the presented source vibrational resonances with energies between 1200 cm-1 and 3200 cm-1 can be accessed with a resolution of 10 cm-1. Additionally, the temporal characteristics of the FWM output have been investigated by a cross-correlation setup, revealing the suitability of the emitted pulses for CARS microscopy. This work marks a significant step towards a simple and powerful all-fiber, maintenance-free multiplex-CARS source for real-world applications outside a laboratory environment.

  7. Electric field strength determination in filamentary DBDs by CARS-based four-wave mixing

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Kettlitz, Manfred; Brandenburg, Ronny; Hoeft, Hans; Czarnetzki, Uwe

    2016-09-01

    The electric field strength is a basic parameter of non-thermal plasmas. Therefore, a profound knowledge of the electric field distribution is crucial. In this contribution a four wave mixing technique based on Coherent Anti-Stokes Raman spectroscopy (CARS) is used to measure electric field strengths in filamentary dielectric barrier discharges (DBDs). The discharges are operated with a pulsed voltage in nitrogen at atmospheric pressure. Small amounts hydrogen (10 vol%) are admixed as tracer gas to evaluate the electric field strength in the 1 mm discharge gap. Absolute values of the electric field strength are determined by calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. Alteration of the electric field strength has been observed during the internal polarity reversal and the breakdown process. In this case the major advantage over emission based methods is that this technique can be used independently from emission, e.g. in the pre-phase and in between two consecutive, opposite discharge pulses where no emission occurs at all. This work was supported by the Deutsche Forschungsgemeinschaft, Forschergruppe FOR 1123 and Sonderforschungsbereich TRR 24 ``Fundamentals of complex plasmas''.

  8. Non-intrusive detection of methanol in gas phase using infrared degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Zhou, J.; Sahlberg, A. L.; Nilsson, H.; Lundgren, E.; Zetterberg, J.

    2015-11-01

    Sensitive and non-intrusive detection of gas-phase methanol with high spatial and temporal resolution has for the first time been reported using mid-infrared degenerate four-wave mixing (IR-DFWM). IR-DFWM spectra of methanol have been successfully recorded in nitrogen-diluted gas flows at room temperature and at 300 °C, by probing ro-vibrational transitions belonging to the fundamental C-H stretching modes, ν 2 and ν 9, and the O-H stretching mode, ν 1. The detection limit of methanol vapor at room temperature and atmospheric pressure is estimated to be 250 ppm with the present setup. Potential interference from CH4 and CO2 is discussed from recorded IR-DFWM spectra of CH4 and CO2, and it was found that detection of methanol free from CH4 and CO2 interference is possible. These results show the potential of the detection of methanol with IR-DFWM for applications in both combustion and catalytic environments, such as CO2 hydrogenation and CH4 oxidation.

  9. Line-space description of resonant four-wave mixing: Theory for isotropic molecular states

    SciTech Connect

    Kouzov, A.; Radi, P.

    2014-05-21

    Based on the quantum Liouville formalism, a theory of the two-color, triply resonant four-wave mixing is developed for molecules with isotropically oriented angular momenta. The approach allows to strictly incorporate the relaxation matrices Γ{sup (r)} (r = 0, 1, 2) into the third-order susceptibility χ{sup (3)} whose expression acquires therewith the form of a scalar product in the line space. Thanks to this representation, isolation of all resonance terms from χ{sup (3)} becomes a routine task. Some of these terms correspond to the case when a molecule initially interacts with two pump photons of the same frequency. Such interactions give rise to the grating line-space vectors which have the same (zero) eigenfrequency. Due to this degeneracy, the latter are easily mixed by rotationally inelastic collisions which shows up in a state-resolved coherence transfer. The satellite signals induced thereby provide a great scope to study the state-to-state inelastic rates in situ by purely optical means. If the diagonal form of Γ is assumed, the satellites become forbidden and our results reduce to conventional expressions for the main resonances. Polarization configurations are designed for direct measurements of the population (r = 0), orientation (r = 1), and alignment (r = 2) contributions to χ{sup (3)}. Finally, depending on the photon-molecule interaction sequence, the resonance terms of χ{sup (3)} are shown to be differently affected by velocity averaging, the effect which conspicuously manifests itself when Doppler broadening becomes paramount.

  10. Higher-Order Squeezing of Quantum Field and the Generalized Uncertainty Relations in Non-Degenerate Four-Wave Mixing

    NASA Technical Reports Server (NTRS)

    Li, Xi-Zeng; Su, Bao-Xia

    1996-01-01

    It is found that the field of the combined mode of the probe wave and the phase-conjugate wave in the process of non-degenerate four-wave mixing exhibits higher-order squeezing to all even orders. And the generalized uncertainty relations in this process are also presented.

  11. Study of degenerate four-wave mixing in germanium and rhenate-doped potassium chloride at carbon dioxide laser wavelengths

    SciTech Connect

    Watkins, D.E.

    1982-02-01

    Theoretical and experimental studies of degenerate four-wave mixing (DFWM) by three different mechanisms are presented. These are the nonlinear index of refraction of a lossless, Kerr-like medium, the saturable absorption of a resonant optical transition, and the formation of a free-carrier grating.

  12. Efficiency of four-wave mixing between orthogonally polarized linear waves and solitons in a birefringent fiber

    NASA Astrophysics Data System (ADS)

    Mas Arabí, C.; Bessin, F.; Kudlinski, A.; Mussot, A.; Skryabin, D.; Conforti, M.

    2016-12-01

    We analyze the interaction between orthogonally polarized solitons and dispersive waves via four-wave mixing in a birefringent fiber. We calculate analytically the efficiency of the phase-sensitive scattering between orthogonally polarized solitons and dispersive waves. Experiments performed by using a photonic crystal fiber perfectly match the analytical predictions.

  13. Optical limiting and degenerate four-wave mixing in novel fullerenes

    NASA Astrophysics Data System (ADS)

    Marciu, Daniela

    1999-09-01

    Two experimental methods, optical limiting and degenerate four-wave mixing, are employed to study the nonlinear optical properties of various novel fullerenes structures. Optical limiting refers to decreased transmittance of a material with increased incident light intensity. Detailed measurements of the wavelength- dependence of fullerene optical limiters have illustrated several key features of reverse saturable absorption. Most important among these is the requirement of weak but non-negligible ground state absorption. We have shown that the optical limiting performance of C60 can be extended into the near infrared range by appropriate modifications of the structure such as higher cage fullerenes or derivatization of the basic C60 molecule. The higher cage fullerene C76 shows improved optical limiting behavior compared to C60, for wavelengths higher than 650 nm, but becomes a weak limiter in the 800 nm range. C84, even at high concentrations in α- chloronaphthalene, does not reach the good performance of C 60, but instead shows weak optical limiting in the 800 nm range. We also demonstrate that by attaching various groups to the C60 molecule, we can extend the optical limiting performance in the near infrared regime. The C60 derivatives studied, (C60 cyclic ketone, C60 secondary amine, C60CHC6H 4CO2H, and C60C4H4(CH 3)CH2O2C(CH2)CO2H), have a similar characteristic: the attached groups cause a symmetry-breaking of the C60 sphere and, therefore, there are new allowed transitions that appear as absorption features up to 750 nm. The optical limiting measurements show that these materials, even for low input energies, have an exceptionally strong optical limiting response in the 640 to 750 nm spectral region. For wavelengths higher than 800 nm, however, they become transparent and no optical limiting is observed. Excited state absorption cross-sections obtained from analysis of the optical limiting data reveal that the C60 derivatives have a maximum triplet

  14. Dissection of rovibronic band structure by polarization-resolved degenerate four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Bracamonte, Alfredo E.; Vaccaro, Patrick H.

    2003-07-01

    Judicious selection of polarization characteristics in degenerate four-wave mixing (DFWM) spectroscopy is shown to provide a facile and robust means for discriminating rovibronic features according to their changes in rotational angular momentum, ΔJ. Building upon a perturbative (weak-field) treatment of the resonant DFWM response, theoretical analyses are presented for a collinear arrangement of linearly polarized electromagnetic waves that interact with an isotropic ensemble of gas-phase target molecules. The polarization unit vectors for two input fields (E1 and E3) are presumed to be fixed along the Y-axis (φ1=φ3=π/2), while the remaining incident field (E2) has its orientation within the transverse X-Y plane specified by angular coordinate φ2. For φ2=π/4, complete elimination of high-J Q-branch (ΔJ=0) and P-/R-branch (ΔJ=±1) structure is found to occur when the detected direction of linear polarization is switched between the limiting values of φ4,Q=-18.43° and φ4,P/R=+26.57°, respectively. These predictions are corroborated experimentally by probing the tunneling-split origin region of the tropolone à 1B2-X˜ 1A1 (π*←π) absorption system under ambient, bulk-gas conditions. Other polarization-based schemes for rovibronic branch suppression are discussed as are the effects incurred by (strong-field) optical saturation phenomena. The implementations of DFWM suggested by this work should prove useful for dissecting and unraveling the congested spectra often exhibited by massive polyatomic species.

  15. Two-color resonant four-wave mixing: a tool for double resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    Rohlfing, Eric A.; Tobiason, Joseph D.; Dunlop, J. R.; Williams, Skip

    1995-09-01

    Two-color resonant four-wave mixing (RFWM) shows great promise in a variety of double- resonance applications in molecular spectroscopy and chemical dynamics. One such application is stimulated emission pumping (SEP), which is a powerful method of characterizing ground-state potential energy surfaces in regions of chemical interest. We use time-independent, diagrammatic perturbation theory to identify the resonant terms in the third- order nonlinear susceptibility for each possible scheme by which two-color RFWM can be used for double-resonance spectroscopy. After a spherical tensor analysis we arrive at a signal expression for two-color RFWM that separates the molecular properties from purely laboratory-frame factors. In addition, the spectral response for tuning the DUMP laser in RFWM-SEP is found to be a simple Lorentzian in free-jet experiments. We demonstrate the utility of RFWM-SEP and test our theoretical predictions in experiments on jet-cooled transient molecules. In experiments on C3 we compare the two possible RFWM-SEP processes and show that one is particularly well-suited to the common situation in which the PUMP transition is strong but the DUMP transitions are weak. We obtain RFWM-SEP spectra of the formyl radical, HCO, that probe quasibound vibrational resonances lying above the low threshold for dissociation to H+CO. Varying the polarization of the input beams or PUMP rotational branch produces dramatic effects in the relative intensities of rotational lines in the RFWM-SEP spectra of HCO; these effects are well described by our theoretical analysis. Finally, RFWM-SEP spectra of HCO resonances that are homogeneously broadened by dissociation confirm the predicted lineshape and give widths that are in good agreement with those determined via unsaturated fluorescence depletion SEP.

  16. All-optical wavelength conversion by four-wave mixing in a semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Lee, Robert Bumju

    1997-11-01

    Wavelength division multiplexed optical communication systems will soon become an integral part of commercial optical networks. A crucial new function required in WDM networks is wavelength conversion, the spectral translation of information-laden optical carriers, which enhances wavelength routing options and greatly improves network reconfigurability. One of several techniques for implementing this function is four-wave mixing utilizing ultra-fast intraband nonlinearities in semiconductor optical amplifiers. The effects of input power, noise prefiltering and semiconductor optical amplifier length on the conversion efficiency and optical signal-to-noise ratio were examined. Systems experiments have been conducted in which several important performance characteristics of the wavelength converter were studied. A bit-error-rate performance of <10-9 at 10 Gb/s was achieved for a record shift of 18 nm down in wavelength and 10 nm up in wavelength. Two cascaded conversions spanning a 40 km fiber link at 10 Gb/s are also demonstrated for conversions of up to 9 nm down and up in wavelength. The dynamic range of input signal power and its impact on the BER performance were studied at 2.5 Gb/s for both a single-channel conversion and a simultaneous 2-channel conversion. The crosstalk penalty induced by parasitic cross-gain modulation in 2-channel conversion is quantified. The spectral inversion which results from the conversion process is studied by time-resolved spectral analysis, and its application as a technique for dispersion compensation is demonstrated. Finally, the application of selective organometallic vapor-phase epitaxy for the formation of highly-uniform and densely-packed arrays of GaAs quantum dots is demonstrated. GaAs dots of 15-20 nm in base diameter and 8-10 nm in height terminated by slow-growth crystallographic planes were grown within dielectric-mask openings and characterized by atomic force microscopy.

  17. Frequency-scanned ultrafast spectroscopic techniques applied to infrared four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Meyer, Kent Albert

    Frequency-scanned techniques of ultrafast spectroscopy were applied to infrared four-wave mixing (IRFWM) in order to determine their effectiveness in the detection and quantification of vibrationally coupled modes. Frequency-scanned ultrafast techniques are a mixed version of frequency and time domain approaches with some advantages of each domain. The frequency domain advantages include the ability to select individual components from a mixture; time domain advantages include the ability to temporally discriminate many non-linear pathways that can congest spectra and interpretation. These advantages have been experimentally verified with doubly vibrationally enhanced (DOVE) and triply vibrationally enhanced (TRIVE) FWM using dilute carbon disulfide as a model system. DOVE and TRIVE are multi-dimensional vibrational coupling techniques analogous to multi-dimensional NMR spin coupling techniques. They differ from NMR in that DOVE and TRIVE spectroscopy occur on the ultrafast (<1 ps) timescale and can provide new chemical dynamics information. Quantification of DOVE signal has been performed computationally of dilute carbon disulfide and agrees with values extracted from linear infrared spectra. Additional parameters from computational models show population dephasing contributions of dilute carbon disulfide's major combination band and strongly absorbing fundamental to be values not far from expected ones. An advantage of TRIVE over the standard IR-IR pump-probe methods is in the possible reduction of the total number of interfering pathways. Pathways not typically explored in the pump-probe paths may be useful in their line narrowing of correlated vibrational modes. The issue of broadening of spectral lines in mixed domain spectra due to the breadth of the electric fields has been addressed with the concept of gated line narrowing. Shaped input pulses can narrow homogeneously broadened lines when gated at a far time. In TRIVE, gating can take place in the form of

  18. Final Report: Investigation of Polarization Spectroscopy and Degenerate Four-Wave Mixing for Quantitative Concentration Measurements

    SciTech Connect

    Robert P. Lucht

    2005-03-09

    Laser-induced polarization spectroscopy (LIPS), degenerate four-wave mixing (DFWM), and electronic-resonance-enhanced (ERE) coherent anti-Stokes Raman scattering (CARS) are techniques that shows great promise for sensitive measurements of transient gas-phase species, and diagnostic applications of these techniques are being pursued actively at laboratories throughout the world. However, significant questions remain regarding strategies for quantitative concentration measurements using these techniques. The primary objective of this research program is to develop and test strategies for quantitative concentration measurements in flames and plasmas using these nonlinear optical techniques. Theoretically, we are investigating the physics of these processes by direct numerical integration (DNI) of the time-dependent density matrix equations that describe the wave-mixing interaction. Significantly fewer restrictive assumptions are required when the density matrix equations are solved using this DNI approach compared with the assumptions required to obtain analytical solutions. For example, for LIPS calculations, the Zeeman state structure and hyperfine structure of the resonance and effects such as Doppler broadening can be included. There is no restriction on the intensity of the pump and probe beams in these nonperturbative calculations, and both the pump and probe beam intensities can be high enough to saturate the resonance. As computer processing speeds have increased, we have incorporated more complicated physical models into our DNI codes. During the last project period we developed numerical methods for nonperturbative calculations of the two-photon absorption process. Experimentally, diagnostic techniques are developed and demonstrated in gas cells and/or well-characterized flames for ease of comparison with model results. The techniques of two-photon, two-color H-atom LIPS and three-laser ERE CARS for NO and C{sub 2}H{sub 2} were demonstrated during the

  19. Influence of temperature and free carries on four-wave mixing in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Makhonin, M. N.; Krizhanovskii, D. N.; Dremin, A. N.; Tartakovskii, A. I.; Kulakovskii, V. D.; Gippius, N. A.; Skolnick, Maurice S.; Roberts, John S.

    2003-06-01

    In semiconductor microcavities (MCs) with embedded quantum wells (QW) a strong two-dimensional (2D) confinement of the light in the growth direction leads to an enhanced exciton-photon interaction, which results in the formation of mixed exciton-photon states described in terms of quasi 2D-polaritons. The density of these states is strongly reduced compared to exciton one, due to a very small in-plane mass. As a result, one can hope that the high filling of the polariton states near the polariton band bottom can be achieved at relatively small total density without destroying the strong coupling regime. However such a filling never was reached at low excitation density range where the polariton relaxation to the polariton branch bottom is determined by the emission of acoustic phonons. The reason is in the fact that the polariton lifetime is comparable with phonon scattering time. As a result, the energy distribution of polaritons clearly demonstrates 'bottleneck effect' both under the above band gap excitation and the resonant excitation below free exciton level. However the high occupation of polariton states near the band bottom is relatively easy reached under conditions of a strong resonant excitation into the lower polariton (LP) branch at particular wavenumbers close to the inflection point of the LP dispersion. It is explained as the result of stimulated hyper-Raman scattering (or four-wave mixing) of pumped polaritons with (Ep, kp) to states with the energy and momentum [E1, k1 approximately 0] and [E2 = 2Ep - E1, k2 = 2kp], which referred to as the 'signal' and 'idler,' respectively. Here we investigate the influence of a temperature and an additional above band gap excitation on the stimulated scattering in MCs. A GaAs/AlAs MC containing 6 InGaAs quantum wells in the active layer (Rabi splitting Ω of 6 - 7 meV) has been investigated in a wide range of detunings between free exciton level and bottom of the photonic mode from δ = 0 to -3 meV. The

  20. Four-wave-mixing spectroscopy of localized excitons in CdS 1- xSe x

    NASA Astrophysics Data System (ADS)

    Dinger, A.; Ell, R.; Reznitsky, A.; Klingshirn, C.

    2000-06-01

    We investigated the dephasing properties of excitons in CdS 1- xSe x in the compositional range 0.07≲ x≲0.80 by means of transient four-wave-mixing experiments. For 0.35≲ x≲0.80, the dephasing times of localized excitons are in the order of a few 100 ps up to 1 ns. Thereby, we observe a strong dependence of the dephasing times on the composition x, the localization depth and the spectral excitation width. For very short delay times (a few ps), a beat phenomenon is presented which is interpreted by multiple reflections of propagating exciton-polariton wave packets. In the compositional range 0.07≲ x≲0.35 the four-wave-mixing signal is strongly suppressed and the slowly dephasing signal is hardly observable or as in the most cases not measureable at all.

  1. Broad bandwidth third-harmonic generation via four-wave mixing and stimulated Raman scattering in a microcavity.

    PubMed

    Chen-Jinnai, Akitoshi; Kato, Takumi; Fujii, Shun; Nagano, Takuma; Kobatake, Tomoya; Tanabe, Takasumi

    2016-11-14

    We generate broad bandwidth visible light ranging from 498 to 611 nm via third-harmonic generation in a silica toroid microcavity. The silica toroid microcavity is fed with a continuous-wave input at a telecom wavelength, where third-harmonic generation follows the generation of an infrared Kerr comb via cascaded four-wave-mixing and stimulated Raman scattering effects. Thanks to these cascaded effects (four-wave mixing, stimulated Raman scattering, and third-harmonic generation) in an ultrahigh-Q microcavity, a broad bandwidth visible light is obtained. The visible light couples with the whispering gallery mode of the cavity by demonstrating the evanescent coupling of the generated visible light with a tapered fiber based on an add-drop configuration.

  2. Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator

    NASA Astrophysics Data System (ADS)

    Yang, Yong; Jiang, Xuefeng; Kasumie, Sho; Zhao, Guangming; Xu, Linhua; Ward, Jonathan M.; Yang, Lan; Chormaic, Síle Nic

    2016-11-01

    Frequency comb generation in microresonators at visible wavelengths has found applications in a variety of areas such as metrology, sensing, and imaging. To achieve Kerr combs based on four-wave mixing in a microresonator, dispersion must be in the anomalous regime. In this work, we demonstrate dispersion engineering in a microbubble resonator (MBR) fabricated by a two-CO$_2$ laser beam technique. By decreasing the wall thickness of the MBR down to 1.4 $\\mu$m, the zero dispersion wavelength shifts to values shorter than 764 nm, making phase matching possible around 765 nm. With the optical \\textit{Q}-factor of the MBR modes being greater than $10^7$, four-wave mixing is observed at 765 nm for a pump power of 3 mW. By increasing the pump power, parametric oscillation is achieved, and a frequency comb with 14 comb lines is generated at visible wavelengths.

  3. Design and optimization of highly nonlinear low-dispersion crystal fiber with high birefringence for four-wave mixing.

    PubMed

    Zhang, Ya-Ni; Ren, Li-Yong; Gong, Yong-Kang; Li, Xiao-Hui; Wang, Lei-Ran; Sun, Chuan-Dong

    2010-06-01

    We have proposed a novel type of photonic crystal fiber (PCF) with low dispersion and high nonlinearity for four-wave mixing. This type of fiber is composed of a solid silica core and a cladding with a squeezed hexagonal lattice elliptical airhole along the fiber length. Its dispersion and nonlinearity coefficient are investigated simultaneously by using the full vectorial finite element method. Numerical results show that the proposed highly nonlinear low-dispersion fiber has a total dispersion as low as +/-2.5 ps nm(-1) km(-1) over an ultrabroad wavelength range from 1.43 to 1.8 microm, and the corresponding nonlinearity coefficient and birefringence are about 150 W(-1) km(-1) and 2.5x10(-3) at 1.55 microm, respectively. The proposed PCF with low ultraflattened dispersion, high nonlinearity, and high birefringence can have important application in four-wave mixing.

  4. Generation of 12 fs deep-ultraviolet pulses by four-wave mixing through filamentation in neon gas.

    PubMed

    Fuji, Takao; Horio, Takuya; Suzuki, Toshinori

    2007-09-01

    Generation of deep-ultraviolet femtosecond pulses by four-wave mixing through filamentation in neon gas was demonstrated. Fundamental (omega) and second-harmonic (2omega) pulses of 25 fs Ti:sapphire amplifier output were focused into neon gas, and 20 microJ pulses with the center wavelength of 260 nm were produced by a four-wave mixing process, 2omega+2omega-omega?3omega through an ~15 cm filament. Additionally, pulses with an energy of 2 microJ at 200 nm were generated, probably by a cascaded process, 3omega+2omega-omega?4omega. The 260 nm pulses were compressed by a grating-based compressor and characterized by a dispersion-free transient grating frequency-resolved optical gating. The estimated pulse width was 12 fs.

  5. Buffer gas-assisted four-wave mixing resonances in alkali vapor excited by a single cw laser

    NASA Astrophysics Data System (ADS)

    Shmavonyan, Svetlana; Khanbekyan, Aleksandr; Khanbekyan, Alen; Mariotti, Emilio; Papoyan, Aram V.

    2016-12-01

    We report the observation of a fluorescence peak appearing in dilute alkali (Rb, Cs) vapor in the presence of a buffer gas when the cw laser radiation frequency is tuned between the Doppler-broadened hyperfine transition groups of an atomic D2 line. Based on steep laser radiation intensity dependence above the threshold and spectral composition of the observed features corresponding to atomic resonance transitions, we have attributed these features to the buffer gas-assisted four-wave mixing process.

  6. Observation of parametric gain due to four-wave mixing in dispersion engineered GaInP photonic crystal waveguides.

    PubMed

    Colman, Pierre; Cestier, Isabelle; Willinger, Amnon; Combrié, Sylvain; Lehoucq, Gaëlle; Eisenstein, Gadi; De Rossi, Alfredo

    2011-07-15

    We investigate four-wave mixing (FWM) in GaInP 1.5 mm long dispersion engineered photonic crystal waveguides. We demonstrate an 11 nm FWM bandwidth in the CW mode and a conversion efficiency of -24 dB in the quasi-CW mode. For picosecond pump and probe pulses, we report a 3 dB parametric gain and nearly a -5 dB conversion efficiency at watt-level peak pump powers.

  7. Extinction ratio improvement by pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber.

    PubMed

    Chow, K K; Shu, C; Lin, Chinlon; Bjarklev, A

    2005-10-31

    We demonstrate extinction ratio improvement by using pump-modulated four-wave mixing in a dispersion-flattened nonlinear photonic crystal fiber. A 6-dB improvement in the extinction ratio of a degraded return-to-zero signal has been achieved. A power penalty improvement of 3 dB at 10(-9) bit-error-rate level is obtained in the 10 Gb/s bit-error-rate measurements.

  8. Efficiency of four-wave mixing in injection-locked InAs/GaAs quantum-dot lasers

    NASA Astrophysics Data System (ADS)

    Huang, H.; Arsenijević, D.; Schires, K.; Sadeev, T.; Erasme, D.; Bimberg, D.; Grillot, F.

    2016-12-01

    Frequency conversion using highly non-degenerate four-wave mixing is investigated in optically injection-locked InAs/GaAs quantum-dot Fabry-Perot lasers with different ridge waveguide dimensions. Conversion efficiencies up to -16 dB with a large optical signal-to-noise ratios of 36 dB are unveiled. The conversion bandwidth is extended to 4 THz with a quasi-symmetrical response between up- and down-converted signals.

  9. Experimental investigation of combined four-wave mixing and Raman effect in the normal dispersion regime of a photonic crystal fiber.

    PubMed

    Kudlinski, A; Pureur, V; Bouwmans, G; Mussot, A

    2008-11-01

    We study the effect of stimulated Raman scattering on four-wave mixing sidebands generated by pumping in the normal dispersion regime of a photonic crystal fiber. Q-switch nanosecond pulses at 1064 nm are used to generate signal and idler wavelengths by degenerate four-wave mixing. These three waves generate their own Raman Stokes orders, leading to a broadband supercontinuum.

  10. Simulation of pattern and defect detection in periodic amplitude and phase structures using photorefractive four-wave mixing

    NASA Astrophysics Data System (ADS)

    Nehmetallah, Georges; Banerjee, Partha; Khoury, Jed

    2015-03-01

    The nonlinearity inherent in four-wave mixing in photorefractive (PR) materials is used for adaptive filtering. Examples include script enhancement on a periodic pattern, scratch and defect cluster enhancement, periodic pattern dislocation enhancement, etc. through intensity filtering image manipulation. Organic PR materials have large space-bandwidth product, which makes them useful in adaptive filtering techniques in quality control systems. For instance, in the case of edge enhancement, phase conjugation via four-wave mixing suppresses the low spatial frequencies of the Fourier spectrum of an aperiodic image and consequently leads to image edge enhancement. In this work, we model, numerically verify, and simulate the performance of a four wave mixing setup used for edge, defect and pattern detection in periodic amplitude and phase structures. The results show that this technique successfully detects the slightest defects clearly even with no enhancement. This technique should facilitate improvements in applications such as image display sharpness utilizing edge enhancement, production line defect inspection of fabrics, textiles, e-beam lithography masks, surface inspection, and materials characterization.

  11. Kinetic Temperature and Electron Density Measurement in an Inductively Coupled Plasma Torch using Degenerate Four-Wave Mixing

    NASA Technical Reports Server (NTRS)

    Schafer, Julia; Lyons, Wendy; Tong, WIlliam G.; Danehy, Paul M.

    2008-01-01

    Laser wave mixing is presented as an effective technique for spatially resolved kinetic temperature measurements in an atmospheric-pressure radio-frequency inductively-coupled plasma. Measurements are performed in a 1 kW, 27 MHz RF plasma using a continuous-wave, tunable 811.5-nm diode laser to excite the 4s(sup 3)P2 approaches 4p(sup 3)D3 argon transition. Kinetic temperature measurements are made at five radial steps from the center of the torch and at four different torch heights. The kinetic temperature is determined by measuring simultaneously the line shape of the sub-Doppler backward phase-conjugate degenerate four-wave mixing and the Doppler-broadened forward-scattering degenerate four-wave mixing. The temperature measurements result in a range of 3,500 to 14,000 K+/-150 K. Electron densities measured range from 6.1 (+/-0.3) x 10(exp 15)/cu cm to 10.1 (+/-0.3) x 10(exp 15)/cu cm. The experimental spectra are analyzed using a perturbative treatment of the backward phase-conjugate and forward-geometry wave-mixing theory. Stark width is determined from the collisional broadening measured in the phase-conjugate geometry. Electron density measurements are made based on the Stark width. The kinetic temperature of the plasma was found to be more than halved by adding deionized water through the nebulizer.

  12. Optical four-wave mixing and generation of squeezed light in an optomechanical cavity driven by a bichromatic field

    NASA Astrophysics Data System (ADS)

    Garcés, Rafael; de Valcárcel, Germán. J.

    2014-05-01

    We show that an optomechanical cavity pumped by a bichromatic light beam can generate a signal whose frequency lies halfway between the two driving frequencies. This process can be understood as a degenerate four-wave mixing, in which two pump photons (one from each frequency) are combined to yield two identical signal photons. This process takes place between a lower and an upper threshold in terms of the pump intensity, which depend on the pump frequency difference. Close to the signal oscillation threshold a clear noise reduction in one of its quadratures is shown numerically.

  13. Generation of a single-photon source via a four-wave mixing process in a cavity

    SciTech Connect

    Fan Bixuan; Duan Zhenglu; Zhou Lu; Yuan Chunhua; Zhang Weiping; Ou, Z. Y.

    2009-12-15

    It is shown that an efficient, well-directional single-photon source can be realized via a four-wave mixing process in a cavity. The probability of producing a single-photon state nearly approaches 50%. The bandwidth of single-photons generated in this way is controllable, which is determined by that of the input pulse. Furthermore, we propose a scheme to generate a coherent multichannel single-photon source, which might have significant applications in wavelength division multiplexing quantum key distribution.

  14. Optimisation of 40 Gb/s wavelength converters based on four-wave mixing in a semiconductor optical amplifier

    NASA Astrophysics Data System (ADS)

    Schulze, K.; Petersen, M. N.; Herrera, J.; Ramos, F.; Marti, J.

    2007-08-01

    The optimum operating powers and wavelengths for a 40 Gb/s wavelength converter based on four-wave mixing in a semiconductor optical amplifier are inferred from experimental results. From these measurements, some general rules of thumb are derived for this kind of devices. Generally, the optimum signal power should be 10 dB lower than the pump power (-16 dB conversion efficiency) whereas the wavelength separation between the signal and the pump carrier should not be lower than about four times the signal bitrate (1.3 nm for 40 Gb/s RZ signals).

  15. Optical parametric oscillator based on degenerate four-wave mixing in suspended core tellurite microstructured optical fiber.

    PubMed

    Zhang, Lei; Tuan, Tong Hoang; Kawamura, Harutaka; Suzuki, Takenobu; Ohishi, Yasutake

    2015-10-05

    We report on a suspended core tellurite microstructured optical fiber (TMOF) based optical parametric oscillator (OPO). The intracavity gain is provided by the degenerate four-wave mixing (DFWM) occurred in a 1.5-m-long TMOF synchronously pumped by a mode-locked picosecond erbium-doped fiber laser. The oscillated signal can be generated from 1606 nm to 1743.5 nm, and the idler can be emited from 1526.8 nm to 1395 nm by adjusting the pump wavelength from 1565.4 nm to 1551 nm. A total intenal conversion efficiency of -17.2 dB has been achieved.

  16. Realization of low frequency and controllable-bandwidth squeezing based on a four-wave-mixing amplifer in rubidium vapor

    SciTech Connect

    Liu, Cunjin; Jing, Jietai; Zhou, Zhifan; Pooser, Raphael C; Hudelist, Florian; Zhang, Weiping

    2011-01-01

    We experimentally demonstrate the creation of two correlated beams generated by a nondegenerate four-wave-mixing amplifier at {lambda} = 795 nm in hot rubidium vapor. We achieve intensity difference squeezing at frequencies as low as 1.5 kHz which is so far the lowest frequency to observe squeezing in an atomic system. The squeezing spans from 5.5 to 16.5 MHz with a maximum squeezing of {approx}5 dB at 1 MHz. We can control the squeezing bandwidth by changing the pump power. Both low frequency and controllable bandwidth squeezing show great potential in sensitivity detection and precise control of the atom optics measurement.

  17. Characterization of Pairwise Correlations from Multiple Quantum Correlated Beams Generated from Cascaded Four-Wave Mixing Processes

    PubMed Central

    Wang, Hailong; Cao, Leiming; Jing, Jietai

    2017-01-01

    We theoretically characterize the performance of the pairwise correlations (PCs) from multiple quantum correlated beams based on the cascaded four-wave mixing (FWM) processes. The presence of the PCs with quantum corre- lation in these systems can be verified by calculating the degree of intensity difference squeezing for any pair of all the output fields. The quantum correlation characteristics of all the PCs under different cascaded schemes are also discussed in detail and the repulsion effect between PCs in these cascaded FWM processes is theoretically predicted. Our results open the way for the classification and application of quantum states generated from the cascaded FWM processes. PMID:28071759

  18. Wavelength conversion of 28 GBaud 16-QAM signals based on four-wave mixing in a silicon nanowire.

    PubMed

    Adams, Rhys; Spasojevic, Mina; Chagnon, Mathieu; Malekiha, Mahdi; Li, Jia; Plant, David V; Chen, Lawrence R

    2014-02-24

    We demonstrate error-free wavelength conversion of 28 GBaud 16-QAM single polarization (112 Gb/s) signals based on four-wave mixing in a dispersion engineered silicon nanowire (SNW). Wavelength conversion covering the entire C-band is achieved using a single pump. We characterize the performance of the wavelength converter subsystem through the electrical signal to noise ratio penalty as well as the bit error rate of the converted signal as a function of input signal power. Moreover, we evaluate the degradation of the optical signal to noise ratio due to wavelength conversion in the SNW.

  19. Low-power continuous-wave four-wave mixing wavelength conversion in AlGaAs-nanowaveguide microresonators.

    PubMed

    Kultavewuti, Pisek; Pusino, Vincenzo; Sorel, Marc; Stewart Aitchison, J

    2015-07-01

    We experimentally demonstrate enhanced wavelength conversion in a Q∼7500 deeply etched AlGaAs-nanowaveguide microresonator via degenerate continuous-wave four-wave mixing with a pump power of 24 mW. The maximum conversion efficiency is -43  dB and accounts for 12 dB enhancement compared to that of a straight nanowaveguide. The experimental results and theoretical predictions agree very well and show optimized conversion efficiency of -15  dB. This work represents a step toward realizing a fully integrated optical devices for generating new optical frequencies.

  20. Line space theory of Resonant Four-Wave Mixing: New prospects for all-optical studies of photofragment states

    NASA Astrophysics Data System (ADS)

    Kouzov, A. P.; Radi, P. P.

    2017-04-01

    Based on the line-space quantum formalism, the potential of Resonant Four-Wave Mixing spectroscopy as a new tool to study rotational and translational anisotropy of photofragments produced by absorption of plane-polarized photons is theoretically addressed. Synergy of the flexible polarization setup, fine quantum state resolution and of the possibility to study translational recoil distributions, makes the tool unsurpassed among the all-optical means to interrogate the photofragment states. It allows to directly separate signals induced by the rotational anisotropy which remain silent in the most of laser-induced fluorescence responses and thus opens new ways to study rotational helicity, a crucial signature of the photolysis pathway.

  1. Depolarization technique for wavelength conversion using four-wave mixing in a dispersion-flattened photonic crystal fiber.

    PubMed

    Yang, Taotao; Shu, Chester; Lin, Chinlon

    2005-07-11

    We have developed a depolarization technique to achieve polarization-insensitive wavelength conversion using four-wave mixing in an optical fiber. A maximum conversion efficiency of -11.79 dB was achieved over a 3 dB bandwidth of 26 nm in a 100-m-long dispersion-flattened photonic crystal fiber. The polarization-dependent conversion efficiency was less than 0.38 dB and the measured power penalty for a 10 Gbit/s NRZ signal was 1.9 dB. The relation between the conversion efficiency and the degree of polarization of the pump was also formulated.

  2. Time domain switching/demultiplexing using four wave mixing in GaInP photonic crystal waveguides.

    PubMed

    Cestier, I; Willinger, A; Eckhouse, V; Eisenstein, G; Combrié, S; Colman, P; Lehoucq, G; De Rossi, A

    2011-03-28

    We describe dynamical four wave mixing (FWM) functionalities of an GaInP photonic crystal waveguide. A W1 waveguide was used to wavelength convert 100 ps pulses and for sampling a 10.56 Gbit/s data stream so as to time demultiplex it into 16 or 32 channels. In all cases, the extracted pulses at the idler wavelength are undistorted and have a high signal to noise ratio proving the high efficiency and the versatility of the FWM process in the GaInP PhC waveguides we used.

  3. Phase-matched four wave mixing and quantum beam splitting of matter waves in a periodic potential

    SciTech Connect

    Hilligsoee, Karen Marie; Moelmer, Klaus

    2005-04-01

    We show that the dispersion properties imposed by an external periodic potential ensure both energy and quasimomentum conservation such that correlated pairs of atoms can be generated by four wave mixing from a Bose-Einstein condensate moving in an optical lattice potential. In our numerical solution of the Gross-Pitaevskii equation, a condensate with initial quasimomentum k{sub 0} is transferred almost completely (>95%) into a pair of correlated atomic components with quasimomenta k{sub 1} and k{sub 2}, if the system is seeded with a smaller number of atoms with the appropriate quasimomentum k{sub 1}.

  4. Competition between two-photon-resonant three-photon ionization and four-wave mixing in Xe

    SciTech Connect

    Nagai, Hidekazu; Nakanaga, Taisuke

    2011-12-15

    Competitive inhibition of a resonance enhanced multiphoton ionization process by a resonant four-wave mixing has been observed in Xe atoms. When an intense IR (1064 nm) laser was applied to a sample of Xe which was also being irradiated by a UV laser tuned to the two-photon absorption line of Xe, the two-photon-resonant three-photon ionization signals decreased with increasing IR laser power. This phenomenon is dependent on the resonant states of Xe and the polarization of the two laser beams. Three 6s excited states [5/2]{sub 2}, [3/2]{sub 2}, and [1/2]{sub 0} were examined. At the [1/2]{sub 0} resonant state, the ion signals were not decreased but slightly increased with the increase of the IR laser power. No suppression of the ion signal was observed at the [5/2]{sub 2} resonant state, when the polarization directions of the lasers were perpendicular to each other. The result of the polarization dependence reflects the selection rules of four-wave mixing. A simple rate equation analysis including the contribution of two-photon ionization from the [1/2]{sub 0} state by the IR laser well represents the IR laser-power dependence of the ion signal.

  5. Four-wave mixing parametric oscillation and frequency comb generation at visible wavelengths in a silica microbubble resonator.

    PubMed

    Yang, Yong; Jiang, Xuefeng; Kasumie, Sho; Zhao, Guangming; Xu, Linhua; Ward, Jonathan M; Yang, Lan; Chormaic, Síle Nic

    2016-11-15

    Frequency comb generation in microresonators at visible wavelengths has found applications in a variety of areas such as metrology, sensing, and imaging. To achieve Kerr combs based on four-wave mixing in a microresonator, dispersion must be in the anomalous regime. In this Letter, we demonstrate dispersion engineering in a microbubble resonator (MBR) fabricated by a two-CO2 laser beam technique. By decreasing the wall thickness of the MBR to 1.4 μm, the zero dispersion wavelength shifts to values shorter than 764 nm, making phase matching possible around 765 nm. With the optical Q-factor of the MBR modes being greater than 107, four-wave mixing is observed at 765 nm for a pump power of 3 mW. By increasing the pump power, parametric oscillation is achieved, and a frequency comb with 14 comb lines is generated at visible wavelengths.

  6. Increased Cross-Correlation in Cascaded Four-Wave Mixing Processes

    DTIC Science & Technology

    2007-06-11

    over the spontaneous non- degenerate FWM process ωP1 +ωP2 = ωst + ωas in creating stokes (ωst) and anti-stokes (ωas) light in the spectral side bands...Study of cross-correlation between the created stokes and anti- stokes light is of special interest for the generation of squeezed states [14] or...interest in studying the correlation between the stokes and anti-stokes light created in a degenerate FWM process with a single pump wavelength [18, 19

  7. Dual-pumped nondegenerate four-wave mixing in semiconductor laser with a built-in external cavity

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Wei; Qiu, Qi; Hyub Won, Yong

    2017-04-01

    In this paper, a semiconductor laser system consisting of a conventional multimode Fabry-Pérot laser diode with a built-in external cavity is presented and demonstrated. More than two resonance modes, whose peak levels are significantly higher than other residual modes, are simultaneously supported and output by adjusting the bias current and operating temperature of the active region. Based on this device, dual-pumped nondegenerate four-wave mixing—in which two pump waves and a single signal wave are simultaneously fed into the laser, and the injection power and wavelength of the injected pump and signal waves are changed—is observed and discussed thoroughly. The results show that while the wavelengths of pump wave A and signal wave S are kept constant, the other pump wave B jumps from about 1535 nm to 1578 nm, generating conversion signals with changed wavelengths. The achieved conversion bandwidth between the primary signal and the converted signal waves is broadly tunable in the range of several terahertz frequencies. Both the conversion efficiency and optical signal-to-noise ratio of the newly generated conversion signals are adopted to evaluate the performance of the proposed four-wave mixing process, and are strongly dependent on the wavelength and power of the injected waves. Here, the attained maximum conversion efficiency and optical signal-to-noise ratio are close to -22 dB and 15 dB, respectively.

  8. Two-Photon Absorption and Two-Photon Four-Wave Mixing for the Terbium Ion in Insulators.

    NASA Astrophysics Data System (ADS)

    Huang, Jin

    Resonant enhancement of over two orders of magnitude of direct two-photon absorption from the ground state ^7F_6 to the excited state ^5G_6 of the 4f^8 configuration of Tb^{3+} at 40,200 cm ^{-1} has been observed in time resolved experiments with two separate lasers. The results provide clear evidence for resonant enhancement of two-photon absorption in rare earth compounds and imply the same for Raman scattering. Two separate transition mechanisms have been observed. When a single laser frequency was used, the intermediate states making the largest contribution were from excited configurations of opposite parity which were far from resonance. Detailed two-frequency experiments showed, however, that near the single photon resonance, there was a much stronger contribution from the 4f ^8 configuration ^5D _4 intermediate state. The phase-matching-induced frequency selectivity in the single-photon-resonant four-wave mixing has been observed in further rare earth compounds. These observations provide additional evidence that the phase matching effects, resulting from anomalous dispersion associated with the single-photon resonance, play a major role in determining both the intensity and the line narrowing of the mixing signal, and that similar effects will be observable in any rare earth compound. An effect of two-photon-resonant four-wave mixing has been observed for a transition to the 4f^8 configuration ^5K _8 state of the Tb^{3+ } ion in LiYF_4. The strength of the resonance is comparable to that of single -photon resonances. This technique holds promise as a new spectroscopic tool, especially for studies of two-photon transitions in non-fluorescent materials.

  9. Frequency shift in three-photon resonant four-wave mixing by internal atom-field interaction

    NASA Astrophysics Data System (ADS)

    de Melo, Natalia R.; Vianna, Sandra S.

    2015-11-01

    We report on experimental results of four-wave mixing processes in rubidium vapor where coherence is induced on the three-photon resonant transition from 5 s to 6 p states via intermediate Rydberg levels. It is shown that the use of two beams in a noncollinear configuration, i.e., θ ≠0 , and high atomic density unveil new features. First, the θ =0 (collinear configuration) odd-photon destructive interference between the incident and generated fields is strongly inhibited for θ ≠0 . Second, most importantly, the observed cooperative frequency shift of the three-photon transition is strongly enhanced for small, but nonzero, values of θ due to the factor (1-cosθ ) -1, which is not present if the generated radiation field is not considered self-consistently in the Maxwell-Bloch equations.

  10. Electromagnetically induced transparency and four-wave mixing in a cold atomic ensemble with large optical depth

    NASA Astrophysics Data System (ADS)

    Geng, J.; Campbell, G. T.; Bernu, J.; Higginbottom, D. B.; Sparkes, B. M.; Assad, S. M.; Zhang, W. P.; Robins, N. P.; Lam, P. K.; Buchler, B. C.

    2014-11-01

    We report on the delay of optical pulses using electromagnetically induced transparency (EIT) in an ensemble of cold atoms with an optical depth exceeding 500. To identify the regimes in which four-wave mixing (4WM) impacts on EIT behaviour, we conduct the experiment in both 85Rb and 87Rb. Comparison with theory shows excellent agreement in both isotopes. In 87Rb negligible 4WM was observed and we obtained one pulse-width of delay with 50% efficiency. In 85Rb 4WM contributes to the output. In this regime we achieve a delay-bandwidth product of 3.7 at 50% efficiency, allowing temporally multimode delay, which we demonstrate by compressing two pulses into the memory medium.

  11. Efficient reflection via four-wave mixing in a Doppler-free electromagnetically-induced-transparency gas system

    SciTech Connect

    Zhou, Hai-Tao; Wang, Dan; Zhang, Jun-Xiang; Wang, Da-Wei; Zhu, Shi-Yao

    2011-11-15

    We experimentally demonstrate the high-efficiency reflection of a probe field in {Lambda}-type three-level atoms of cesium vapor driven by two counterpropagating coupling fields. More than 60% of reflection efficiency is observed at the phase-matching angle. The underlying mechanism theoretically is investigated as the four-wave mixing is enhanced by the electromagnetically-induced transparency. Both of the two Doppler-free two-photon resonances (one for the probe and co-propagating fields, the other for the reflected and the counterpropagation fields) play an important role in satisfying the phase matching in the reflection direction. The phase compensation due to the anomalous dispersion and the decrease of effective absorption length in the atomic system allow the efficient reflection to be observed in a wide range of incident angles of the probe field and detunings of the coupling field.

  12. Analysis of four-wave mixing of high-power lasers for the detection of elastic photon-photon scattering

    SciTech Connect

    Lundin, J.; Marklund, M.; Lundstroem, E.; Brodin, G.; Collier, J.; Bingham, R.; Mendonca, J. T.; Norreys, P.

    2006-10-15

    We derive expressions for the coupling coefficients for electromagnetic four-wave mixing in the nonlinear quantum vacuum. An experimental setup for detection of elastic photon-photon scattering is suggested, where three incoming laser pulses collide and generate a fourth wave with a new frequency and direction of propagation. An expression for the number of scattered photons is derived and, using beam parameters for the Astra Gemini system at the Rutherford Appleton Laboratory, it is found that the signal can reach detectable levels. Problems with shot-to-shot reproducibility are reviewed, and the magnitude of the noise arising from competing scattering processes is estimated. It is found that detection of elastic photon-photon scattering may be achieved.

  13. Four-wave-mixing-based optical parametric oscillator delivering energetic, tunable, chirped femtosecond pulses for non-linear biomedical applications.

    PubMed

    Gottschall, Thomas; Meyer, Tobias; Schmitt, Michael; Popp, Jürgen; Limpert, Jens; Tünnermann, Andreas

    2015-09-07

    A novel concept for an optical parametric oscillator based on four-wave mixing (FOPO) in an optical fiber is presented. This setup has the ability of generating highly chirped signal and idler pulses with compressed pulse durations below 600 fs and pulse energies of up to 250 nJ. At a fixed pump wavelength of 1040 nm, the emerging signal and idler wavelengths can be easily tuned between 867 to 918 nm and 1200 to 1300 nm, respectively, only by altering the cavity length. With compressed peak powers >100 kW and a repetition rate of only 785 kHz, this source provides tunable intense ultra-short pulses at moderate average powers. This setup constitutes a stable, simple and in many ways superior alternative to bulk state-of-the-art OPO light converters for demanding biomedical applications and non-linear microspectroscopy.

  14. Four-wave mixing response of solution-processed CH3NH3PbI3 thin films

    NASA Astrophysics Data System (ADS)

    March, Samuel A.; Riley, Drew B.; Clegg, Charlotte; Webber, Daniel; Todd, Seth; Hill, Ian G.; Hall, Kimberley C.

    2017-02-01

    The interest in perovskite-based solar cell absorber materials has skyrocketed in recent years due to the rapid rise in solar cell efficiency and the potential for cost reductions tied to solution-processed device fabrication. Due to complications associated with the presence of strong static and dynamic disorder in these organic-inorganic materials, the fundamental photophysical behavior of photo-excited charge carriers remains unclear. We apply four-wave mixing spectroscopy to study the charge carrier dynamics in CH3NH3PbI3 thin films. Our experiments reveal two discrete optical transitions below the band gap of the semiconductor with binding energies of 13 meV and 29 meV, attributed to free and defect-bound excitons respectively.

  15. High-quality ultraviolet beam generation in multimode photonic crystal fiber through nondegenerate four-wave mixing at 532 nm.

    PubMed

    Sévigny, Benoit; Cassez, Andy; Vanvincq, Olivier; Quiquempois, Yves; Bouwmans, Géraud

    2015-05-15

    All-fiber ultraviolet (UV) light sources are of great practical interest for a multitude of applications spanned across different sectors, from industrial processes such as nonthermal, high-resolution materials processing, to biomedical applications such as eye surgery, to name a few. However, production of UV light sources with high beam quality has been a problem to this day as the fiber designs required to reach UV wavelengths by four-wave mixing with widely available pumps (i.e., 532 nm) are challenging because of their small size and increased risk of material damage. In this Letter, a specific pumping scheme is presented that allows the conversion of two pump photons in different modes to UV light in the fundamental mode and the corresponding idler in a higher order mode. The process has also been shown to work experimentally, and UV light at 390.5 nm in the fundamental mode was successfully generated.

  16. Graphene-assisted nonlinear optical device for four-wave mixing based tunable wavelength conversion of QPSK signal.

    PubMed

    Hu, Xiao; Zeng, Mengqi; Wang, Andong; Zhu, Long; Fu, Lei; Wang, Jian

    2015-10-05

    We fabricate a nonlinear optical device based on a fiber pigtail cross-section coated with a single-layer graphene grown by chemical vapor deposition (CVD) method. Using such graphene-assisted nonlinear optical device, we experimentally demonstrate tunable wavelength conversion of a 10 Gbaud quadrature phase-shift keying (QPSK) signal by exploiting degenerate four-wave mixing (FWM) progress in graphene. We study the conversion efficiency as functions of the pump power and pump wavelength and evaluate the bit-error rate (BER) performance. The observed optical signal-to-noise ratio (OSNR) penalties for tunable QPSK wavelength conversion are less than 2.2 dB at a BER of 1 × 10(-3).

  17. Diagnostic study of four-wave-mixing-based electric-field measurements in high-pressure nitrogen plasmas.

    PubMed

    Lempert, Walter R; Kearney, Sean P; Barnat, Edward V

    2011-10-10

    We present the results of a diagnostic study of the use of coherent four wave mixing for in situ measurement of an electric field in air or in nitrogen-containing plasmas. Static electric fields in air at a nominal pressure of 625 Torr and temperature of 300 K are detected using vibrational CARS of nitrogen. It is shown that the ratio of the infrared signal to the vibrational N(2) CARS signal is equal to approximately 10(-8) at 8.33 kV/cm, a factor of approximately 50 less than that predicted assuming equal third-order nonlinear susceptibilities. It is also shown that the spatial resolution of a typical collinear geometry measurement is approximately 1 cm. Finally, it is shown that achieving sensitivities of the order of 1 kV/cm requires that the coherent Raman pumping be performed in the highly saturated and Stark broadened regime. © 2011 Optical Society of America

  18. FOUR WAVE MIXING SPECTROSCOPY OF THE NO_3 tilde{B} ^2E' - tilde{X} ^2A_2' transition

    NASA Astrophysics Data System (ADS)

    Fukushima, Masaru; Ishiwata, Takashi

    2014-06-01

    The tilde{B} ^2E' - tilde{X} ^2A_2' electronic transition of NO_3 generated in a supersonic free jet expansion was investigated by four wave mixing ( 4WM ) spectroscopy. The degenerated 4WM and laser induced fluorescence ( LIF ) spectra around the 0_0^0 band region were measured simultaneously. The D4WM spectrum shows broad band features for the 0_0^0 band similar to that of the LIF spectrum. The broad 0_0^0 band does not consist of one sub-band, but of several bands. The intensity distribution of the sub-bands of the D4WM spectrum is similar, but not identical to that of the LIF spectrum.

  19. A novel approach to photonic generate microwave signals based on optical injection locking and four-wave mixing

    NASA Astrophysics Data System (ADS)

    Zhu, Huatao; Wang, Rong; Xiang, Peng; Pu, Tao; Fang, Tao; Zheng, Jilin; Li, Yuandong

    2017-10-01

    In this paper, a novel approach for photonic generation of microwave signals based on frequency multiplication using an injected distributed-feedback (DFB) semiconductor laser is proposed and demonstrated by a proof-of-concept experiment. The proposed system is mainly made up of a dual-parallel Mach-Zehnder modulator (DPMZM) and an injected DFB laser. By properly setting the bias voltage of the DPMZM, ±2-order sidebands with carrier suppression are generated, which are then injected into the slave laser. Due to the optical sideband locking and four-wave mixing (FWM) nonlinearity in the slave laser, new sidebands are generated. Then these sidebands are sent to an optical notch filter where all the undesired sidebands are removed. Finally, after photodetector detection, frequency multiplied microwave signals can be generated. Thanks to the flexibility of the optical sideband locking and FWM, frequency octupling, 12-tupling, 14-tupling and 16-tupling can be obtained.

  20. Broad and tunable multiwavelength fiber laser at the assistance of modulation-instability-assisted four-wave mixing

    NASA Astrophysics Data System (ADS)

    Liu, X. M.

    2010-04-01

    Based on a piece of highly-nonlinear near-zero-dispersion-flattened photonic crystal fiber (PCF), a broadly tunable multiwavelength erbium-doped fiber laser is proposed by using a bi-directionally pumping scheme. This kind of PCF induces the modulation-instability-assisted four-wave mixing to generate new wavelengths. The proposed laser with excellent stability is tunable and switchable by adjusting the fiber Bragg gratings and the variable optical attenuators. The outstanding merits of the proposed multiwavelength laser are the flexible tuning and the ultrabroad spectral range over 150 nm. Especially, the proposed laser source can work at the wavelength of less than 1460 nm, overcoming the limit of gain bandwidth of erbium-doped fiber.

  1. Thermometry of an oxy-acetylene flame using multiplex degenerate four-wave mixing of C2

    NASA Astrophysics Data System (ADS)

    Kaminski, C. F.; Hughes, I. G.; Lloyd, G. M.; Ewart, P.

    1996-01-01

    Thermometry of an oxy-acetylene flame using multiplex Degenerate Four-Wave Mixing (DFWM) of C2 is demonstrated. More than 100 rotational transitions in the d 3 Π g ← a 3 Π u (0,0) Swan band of C2 could be recorded simultaneously by use of a pulsed, broad bandwidth “modeless” laser. Temperatures were inferred by fitting temperature-dependent synthetic spectra of single- or multiple-shot averaged spectra. The strength and reliability of recorded signals together with the large number of rotational lines observed suggest that multiplex DFWM is a promising technique for minor species detection and for temporally resolved temperature measurements in luminous environments. Factors influencing the accuracy and precision of single-shot thermometry using the technique are discussed.

  2. High-power picosecond terahertz-wave generation in photonic crystal fiber via four-wave mixing.

    PubMed

    Wu, Huihui; Liu, Hongjun; Huang, Nan; Sun, Qibing; Wen, Jin

    2011-09-20

    We demonstrate picosecond terahertz (THz)-wave generation via four-wave mixing in an octagonal photonic crystal fiber (O-PCF). Perfect phase-matching is obtained at the pump wavelength of 1.55 μm and a generation scheme is proposed. Using this method, THz waves can be generated in the frequency range of 7.07-7.74 THz. Moreover, peak power of 2.55 W, average power of 1.53 mW, and peak conversion efficiency of more than -66.65 dB at 7.42 THz in a 6.25 cm long fiber are realized with a pump peak power of 2 kW.

  3. Electromagnetically induced transparency-assisted four-wave mixing process in the diamond-type four-level atomic system

    NASA Astrophysics Data System (ADS)

    Wen, Feng; Zheng, Huaibin; Xue, Xinxin; Chen, Haixia; Song, Jianping; Zhang, Yanpeng

    2014-11-01

    With electromagnetically induced transparency (EIT)-assisted configuration, we study the third-order nonlinear four-wave mixing (FWM) process in a diamond-type four-level atomic system both theoretically and experimentally. Following the proposal by the recent study (Willis et al., 2009), we introduce EIT contribution to the theoretical model which will enhance the conversion efficiency of the nonlinear process and narrow the linewidth of the FWM signal. By means of the coherent EIT effect, we get higher conversion efficiency at lower power level of incident beam in such atomic system. Compare to our previous models, the conversion efficiency in such diamond-type atomic system is much smaller which needs higher threshold temperature. In addition, the frequency dependences on incident beams reveal that the dipole transition of one-photon and two-photon processes affect this nonlinear process.

  4. Optical encryption of parallel quadrature phase shift keying signals based on nondegenerate four-wave mixing in highly nonlinear fiber

    NASA Astrophysics Data System (ADS)

    Cui, Yue; Zhang, Min; Zhan, Yueying; Wang, Danshi; Huang, Shanguo

    2016-08-01

    A scheme for optical parallel encryption/decryption of quadrature phase shift keying (QPSK) signals is proposed, in which three QPSK signals at 10 Gb/s are encrypted and decrypted simultaneously in the optical domain through nondegenerate four-wave mixing in a highly nonlinear fiber. The results of theoretical analysis and simulations show that the scheme can perform high-speed wiretapping against the encryption of parallel signals and receiver sensitivities of encrypted signal and the decrypted signal are -25.9 and -23.8 dBm, respectively, at the forward error correction threshold. The results are useful for designing high-speed encryption/decryption of advanced modulated signals and thus enhancing the physical layer security of optical networks.

  5. Four-wave-mixing-based wavelength conversion using a single-walled carbon-nanotube-deposited planar lightwave circuit waveguide.

    PubMed

    Chow, K K; Yamashita, S; Set, S Y

    2010-06-15

    We demonstrated a single-walled carbon-nanotube-deposited planar lightwave circuit (PLC) waveguide for four-wave-mixing (FWM)-based wavelength conversion. FWM is generated from the interaction between the propagating light through the PLC waveguide and the deposited carbon nanotubes (CNTs) on the overcladding-removed core of the waveguide. The third-order nonlinearity of the CNTs is originated from the interband transitions of the pi electrons causing nonlinear polarization similar to other highly nonlinear organic optical materials. FWM-based tunable wavelength conversion of a 10 Gbit/s non-return-to-zero signal is achieved with a power penalty of 3 dB in the bit-error-rate measurements. To our knowledge, this is the first demonstration of a CNT-technology-based device for integrated photonic applications.

  6. Optical frequency combs generated by four-wave mixing in optical fibers for astrophysical spectrometer calibration and metrology.

    PubMed

    Cruz, Flavio C

    2008-08-18

    Optical frequency combs generated by multiple four-wave mixing in short and highly nonlinear optical fibers are proposed for use as high precision frequency markers, calibration of astrophysical spectrometers, broadband spectroscopy and metrology. Implementations can involve two optical frequency standards as input lasers, or one standard and a second laser phase-locked to it using a stable microwave reference oscillator. Energy and momentum conservation required by the parametric generation assures phase coherence among comb frequencies, while fibers with short lengths can avoid linewidth broadening and stimulated Brillouin scattering. In contrast to combs from mode-locked lasers or microcavities, the absence of a resonator allows large tuning of the frequency spacing from tens of gigahertz to beyond teraHertz.

  7. Response functions for dimers and square-symmetric molecules in four-wave-mixing experiments with polarized light.

    PubMed

    Smith, Eric Ryan; Farrow, Darcie A; Jonas, David M

    2005-07-22

    Four-wave-mixing nonlinear-response functions are given for intermolecular and intramolecular vibrations of a perpendicular dimer and intramolecular vibrations of a square-symmetric molecule containing a doubly degenerate state. A two-dimensional particle-in-a-box model is used to approximate the electronic wave functions and obtain harmonic potentials for nuclear motion. Vibronic interactions due to symmetry-lowering distortions along Jahn-Teller active normal modes are discussed. Electronic dephasing due to nuclear motion along both symmetric and asymmetric normal modes is included in these response functions, but population transfer between states is not. As an illustration, these response functions are used to predict the pump-probe polarization anisotropy in the limit of impulsive excitation.

  8. Wavelength conversion for polarization multiplexing signal using four-wave mixing in semiconductor optical amplifier with reduced polarization crosstalk

    NASA Astrophysics Data System (ADS)

    Zhou, Hui; Chen, Ming; Wan, Qiuzhen; Zheng, Zhiwei

    2016-06-01

    We investigated wavelength conversion for polarization multiplexing signal based on four-wave mixing in a semiconductor optical amplifier. We found that the converted signals endured crosstalk among the pol-muxed channels. We also proposed and demonstrated a wavelength conversion scheme with polarization diversity technique. By utilizing the technique, the converted polarization multiplexing signal can be received without crosstalk. In addition, the performance of the proposed system is numerically analyzed with respect to the bit error rate of the converted signal, different frequency spacing between signal and pump and modulated data rate. The simulation results show that the proposed scheme may be a promising method to realize transparent wavelength conversion for polarization multiplexing signals.

  9. Enhanced four-wave-mixing effects by large group indices of one-dimensional silicon photonic crystal waveguides.

    PubMed

    Kim, Dong Wook; Kim, Seung Hwan; Lee, Seoung Hun; Jong, Heung Sun; Lee, Jong-Moo; Lee, El-Hang; Kim, Kyong Hon

    2013-12-02

    Enhanced four-wave-mixing (FWM) effects have been observed with the help of large group-indices near the band edges in one-dimensional (1-D) silicon photonic crystal waveguides (Si PhCWs). A significant increase of the FWM conversion efficiency of about 17 dB was measured near the transmission band edge of the 1-D PhCW through an approximate 3.2 times increase of the group index from 8 to 24 with respect to the central transmission band region despite a large group-velocity dispersion. Numerical analyses based on the coupled-mode equations for the degenerated FWM process describe the experimentally measured results well. Our results indicate that the 1-D PhCWs are good candidates for large group-index enhanced nonlinearity devices even without having any special dispersion engineering.

  10. Enhanced intermodal four-wave mixing for visible and near-infrared wavelength generation in a photonic crystal fiber.

    PubMed

    Yuan, Jinhui; Sang, Xinzhu; Wu, Qiang; Zhou, Guiyao; Li, Feng; Zhou, Xian; Yu, Chongxiu; Wang, Kuiru; Yan, Binbin; Han, Ying; Tam, Hwa Yaw; Wai, P K A

    2015-04-01

    We demonstrate experimentally an enhanced intermodal four-wave mixing (FWM) process through coupling positively chirped femtosecond pulses into the deeply normal dispersion region of the fundamental mode of an in-house fabricated photonic crystal fiber (PCF). In the intermodal phase-matching scheme, the energy of the pump waves at 800 nm in the fundamental mode is efficiently converted into the anti-Stokes waves around 553 nm and the Stokes waves within the wavelength range of 1445-1586 nm in the second-order mode. The maximum conversion efficiency of η(as) and η(s) of anti-Stokes and Stokes waves can be up to 21% and 16%, respectively. The Stokes frequency shift Ω is 5580  cm(-1). The fiber bending and intermodal walk-off effect of pulses do not have significant influence on the nonlinear optical process.

  11. Degenerate four-wave mixing in room-temperature GaAs/GaAlAs multiple quantum well structures

    NASA Astrophysics Data System (ADS)

    Miller, D. A. B.; Chemla, D. S.; Eilenberger, D. J.; Smith, P. W.; Gossard, A. C.; Wiegman, W.

    1983-06-01

    Degenerate four-wave mixing (DFWM) is of current interest both for practical applications (e.g., phase conjugation) and as a physical probe. DFWM makes it possible to detect very small nonlinear changes in refraction. In connection with the present investigation, the first observations of DFWM in GaAs/GaAlAs multiple quantum well structures (MQW's) at room temperature are reported. By combining DFWM and nonlinear absorption results, a direct measurement of the nonlinear refraction near the band gap of the MQW is conducted. The obtained value is compared with previous estimates. The measurements are of practical importance for possible low-power optical devices compatible with laser diodes based either on DFWM, nonlinear refraction (such as optical bistability) of nonlinear absorption. The MQW samples were grown by molecular beam epitaxy (MBE) on GaAs substrates, with the MQW layers sandwiched between GaAlAs cap layers which are transparent at the considered wavelengths.

  12. All-optical logic circuits based on the polarization properties of non-degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Bhardwaj, Ashish Ishwar Singh

    2001-10-01

    This thesis investigates a new class of all-optical logic circuits that are based on the polarization properties of non-degenerate Four-Wave Mixing. Such circuits would be used in conjunction with a data modulation format where the information is coded on the states of polarization of the electric field. Schemes to perform multiple triple- product logic functions are discussed and it is shown that higher-level Boolean operations involving several bits can be implemented without resorting to the standard 2-input gates that are based on some form of switching. Instead, an entire hierarchy of more complex Boolean functions can be derived based on the selection rules of multi-photon scattering processes that can form a new classes of primitive building blocks for digital circuits. Possible applications of these circuits could involve some front-end signal processing to be performed all- optically in shared computer back-planes. As a simple illustration of this idea, a circuit performing error correction on a (3,1) Hamming Code is demonstrated. Error-free performance (Bit Error Rate of <10-9) at 2.5 Gbit/s is achieved after single-error correction on the Hamming word with 50 percent errors. The bit-rate is only limited by the bandwidth of available resources. Since Four-Wave Mixing is an ultrafast nonlinearity, these circuits offer the potential of computing at several terabits per second. Furthermore, it is shown that several Boolean functions can be performed in parallel in the same set of devices using different multi-photon scattering processes. The main objective of this thesis is to motivate a new paradigm of thought in digital circuit design. Challenges pertaining to the feasibility of these ideas are discussed.

  13. Imaging the uptake of gold nanoshells in live cells using plasmon resonance enhanced four wave mixing microscopy

    PubMed Central

    Garrett, Natalie; Whiteman, Matt; Moger, Julian

    2014-01-01

    Gold nanoshells (GNS) are novel metal nanoparticles exhibiting attractive optical properties which make them highly suitable for biophotonics applications. We present a novel investigation using plasmon-enhanced four wave mixing microscopy combined with coherent anti-Stokes Raman scattering (CARS) microscopy to visualize the distribution of 75 nm radius GNS within live cells. During a laser tolerance study we found that cells containing nanoshells could be exposed to < 2.5 mJ each with no photo-thermally induced necrosis detected, while cell death was linearly proportional to the power over this threshold. The majority of the GNS signal detected was from plasmon-enhanced four wave mixing (FWM) that we detected in the epi-direction with the incident lasers tuned to the silent region of the Raman spectrum. The cellular GNS distribution was visualized by combining the epi-detected signal with forwards-detected CARS at the CH2 resonance. The applicability of this technique to real-world nanoparticle dosing problems was demonstrated in a study of the effect of H2S on nanoshell uptake using two donor molecules, NaHS and GYY4137. As GYY4137 concentration was increased from 10 μM to 1 mM, the nanoshell pixel percentage as a function of cell volume (PPCV) increased from 2.15% to 3.77%. As NaHS concentration was increased over the same range, the nanoshell PPCV decreased from 12.67% to 11.47%. The most important factor affecting uptake in this study was found to be the rate of H2S release, with rapid-release from NaHS resulting in significantly greater uptake. PMID:21935123

  14. Imaging the uptake of gold nanoshells in live cells using plasmon resonance enhanced four wave mixing microscopy.

    PubMed

    Garrett, Natalie; Whiteman, Matt; Moger, Julian

    2011-08-29

    Gold nanoshells (GNS) are novel metal nanoparticles exhibiting attractive optical properties which make them highly suitable for biophotonics applications. We present a novel investigation using plasmon-enhanced four wave mixing microscopy combined with coherent anti-Stokes Raman scattering (CARS) microscopy to visualize the distribution of 75 nm radius GNS within live cells. During a laser tolerance study we found that cells containing nanoshells could be exposed to < 2.5 mJ each with no photo-thermally induced necrosis detected, while cell death was linearly proportional to the power over this threshold. The majority of the GNS signal detected was from plasmon-enhanced four wave mixing (FWM) that we detected in the epi-direction with the incident lasers tuned to the silent region of the Raman spectrum. The cellular GNS distribution was visualized by combining the epi-detected signal with forwards-detected CARS at the CH2 resonance. The applicability of this technique to real-world nanoparticle dosing problems was demonstrated in a study of the effect of H2S on nanoshell uptake using two donor molecules, NaHS and GYY4137. As GYY4137 concentration was increased from 10 µM to 1 mM, the nanoshell pixel percentage as a function of cell volume (PPCV) increased from 2.15% to 3.77%. As NaHS concentration was increased over the same range, the nanoshell PPCV decreased from 12.67% to 11.47%. The most important factor affecting uptake in this study was found to be the rate of H2S release, with rapid-release from NaHS resulting in significantly greater uptake.

  15. Travelling-wave resonant four-wave mixing breaks the limits of cavity-enhanced all-optical wavelength conversion

    PubMed Central

    Morichetti, Francesco; Canciamilla, Antonio; Ferrari, Carlo; Samarelli, Antonio; Sorel, Marc; Melloni, Andrea

    2011-01-01

    Wave mixing inside optical resonators, while experiencing a large enhancement of the nonlinear interaction efficiency, suffers from strong bandwidth constraints, preventing its practical exploitation for processing broad-band signals. Here we show that such limits are overcome by the new concept of travelling-wave resonant four-wave mixing (FWM). This approach combines the efficiency enhancement provided by resonant propagation with a wide-band conversion process. Compared with conventional FWM in bare waveguides, it exhibits higher robustness against chromatic dispersion and propagation loss, while preserving transparency to modulation formats. Travelling-wave resonant FWM has been demonstrated in silicon-coupled ring resonators and was exploited to realize a 630-μm-long wavelength converter operating over a wavelength range wider than 60 nm and with 28-dB gain with respect to a bare waveguide of the same physical length. Full compatibility of the travelling-wave resonant FWM with optical signal processing applications has been demonstrated through signal retiming and reshaping at 10 Gb s−1 PMID:21540838

  16. Effects of refractive index changes on four-wave mixing bands in Er-doped photonic crystal fibers pumped at 976 nm.

    PubMed

    Velázquez-Ibarra, L; Díez, A; Andrés, M V; Lucio, J L

    2012-04-01

    An experimental study of the effects of an auxiliary 976 nm pump signal on the four-wave mixing parametric bands generated with a 1064 nm pump in a normal dispersion Er-doped photonic crystal fiber is presented. The four-wave mixing signal and idler bands shift to shorter and longer wavelengths, respectively, with increasing 976 nm pump power. It is shown that the wavelength-dependent resonant refractive index change in the erbium-doped core under 976 nm pumping is at the origin of the effect.

  17. Spectral bandwidth-efficient four-wave mixing minimization scheme for C-band dense wavelength division multiplexed system

    NASA Astrophysics Data System (ADS)

    Singh, Gurpreet; Singh, Maninder Lal

    2017-07-01

    A hybrid suboptimum channel separation (S-CS) scheme is presented. The distinct feature of the scheme is that it selectively minimizes the four-wave mixing (FWM) effect on the worst-affected channels and enhances the performance and spectral bandwidth efficiency in a controlled way. The scheme is helpful in the precise adjustment of tradeoff between immunity from FWM and spectral bandwidth requirement. The simulative comparison of the S-CS with optimum unequal channel separation (OUCS) and equal channel separation (ECS) schemes is performed to show its effectiveness. A dense wavelength division multiplexed system having a total capacity of 1.64 Tb/s in C band is implemented using the presented scheme. A maximum of 82 channels spaced at minimum CS of 50 GHz operating at a data rate of 20 Gb/s for each of the channels is realized using a S-CS (n=12) hybrid scheme. The simulations are performed in the presence of all the linear and nonlinear impairments and noises. A maximum of 480- and 300-km distances using SSMF and ITUT.G655 fibers, respectively, is realized using dispersion-compensating fibers for 82 channels. The ECS and hybrid OUCS can be realized to cover the same distances but with 73 and 79 channels, respectively, due to the realization problem and bandwidth inefficiency.

  18. Modeling interchannel four-wave mixing for 8-Ary modulated dense wavelength division multiplexing systems over dispersion map

    NASA Astrophysics Data System (ADS)

    Du, Jianxin; Shen, Ninghang; Xu, Yue

    2016-08-01

    Semianalytic models are developed to deterministically calculate the variances of degenerate and nondegenerate four-wave mixing (FWM) noises for dispersion-managed dense wavelength division multiplexing (DWDM) systems with 8-Ary modulations [i.e., 8-level amplitude- and differential phase-shift keying (8APSK) and constant-amplitude optical differential 8-level phase-shift keying (D8PSK)]. The semianalytic models include various important propagation effects for exact numerical results. A 5.28-Tb/s (40-Gs/s/ch) 100-GHz-spaced 33-channel DWDM system with a dispersion map is then numerically analyzed by using the newly derived semianalytic models. It is numerically validated that FWM impacts coming from 8APSK pump channels are more severe than those coming from D8PSK ones, where pump channels denote the channels whose energies are transferred to a probe channel through the FWM process. The numerical results show that although FWM tolerance of a central channel with 8APSK is worse than that with D8PSK, a central channel with 8APSK is still superior to that with D8PSK when some linear noises and FWM noise are simultaneously taken into account for our given system conditions, which is mainly attributed to a relatively larger minimum Euclidean distance for the 8APSK constellation than the D8PSK one.

  19. Wavelength-agile high-power sources via four-wave mixing in higher-order fiber modes.

    PubMed

    Demas, J; Prabhakar, G; He, T; Ramachandran, S

    2017-04-03

    Frequency doubling of conventional fiber lasers in the near-infrared remains the most promising method for generating integrated high-peak-power lasers in the visible, while maintaining the benefits of a fiber geometry; but since the shortest wavelength power-scalable fiber laser sources are currently restricted to either the 10XX nm or 15XX nm wavelength ranges, accessing colors other than green or red remains a challenge with this schematic. Four-wave mixing using higher-order fiber modes allows for control of dispersion while maintaining large effective areas, thus enabling a power-scalable method to extend the bandwidth of near-infrared fiber lasers, and in turn, the bandwidth of potential high-power sources in the visible. Here, two parametric sources using the LP0,7 and LP0,6 modes of two step-index multi-mode fibers are presented. The output wavelengths for the sources are 880, 974, 1173, and 1347 nm with peak powers of 10.0, 16.2, 14.7, and 6.4 kW respectively, and ~300-ps pulse durations. The efficiencies of the sources are analyzed, along with a discussion of wavelength tuning and further power scaling, representing an advance in increasing the bandwidth of near-infrared lasers as a step towards high-peak-power sources at wavelengths across the visible spectrum.

  20. [Study of the effect of light source stability on the signal to noise ratio in degenerate four wave mixing experiment].

    PubMed

    Wang, Wei-Bo; Chen, De-Ying; Fan, Rong-Wei; Xia, Yuan-Qin

    2010-02-01

    The effects of the stability of dye laser on the signal to noise ratio in degenerate four-wave mixing (DFWM) were first investigated in iodine vapor using forward geometries. Frequency-doubled outputs from a multi-mode Nd : YAG laser pumped dye laser with laser dye PM580 dissolved in ethanol was used. With the help of forward compensated beam-split technique and imaging detecting system, the saturation intensity of DFWM spectrum in the iodine vapor at 5 554.013 nm was first measured to be 290 microJ under the condition of atmospheric pressure and room temperature. The features of the dye laser such as wavelength ranges, beam quality and energy conversion efficiency decreased gradually with increasing pumping service use, pulse number and intensity. Additionally, with the comparison of the stable and unstable dye laser output, it was found that the instability of dye laser output had greatly influenced the DFWM signal and decreased the signal to background noise ratio. Shot to shot jitter and the broadening in the output frequency leads to an effective broadening of the recorded spectrum and loss of the DFWM signal to noise ratio under the same pumping intensity at different time. The study is of importance to the detection of trace atom, molecule and radical in combustion diagnosis.

  1. Tunable coupled-mode dispersion compensation and its application to on-chip resonant four-wave mixing.

    PubMed

    Gentry, Cale M; Zeng, Xiaoge; Popović, Miloš A

    2014-10-01

    We propose and demonstrate mode coupling as a viable dispersion compensation technique for phase-matched resonant four-wave mixing (FWM). We demonstrate a dual-cavity resonant structure that employs coupling-induced frequency splitting at one of three resonances to compensate for cavity dispersion, enabling phase matching. Coupling strength is controlled by thermal tuning of one cavity enabling active tuning of the resonant frequency matching. In a fabricated silicon microresonator, we show an 8 dB enhancement of seeded FWM efficiency over the noncompensated state. The measured FWM has a peak wavelength conversion efficiency of -37.9  dB across a free spectral range (FSR) of 3.334 THz (∼27  nm), which is, to the best of our knowledge, the largest in a silicon microresonator to demonstrate FWM to date. This form of dispersion compensation can be beneficial for many devices, including wavelength converters, parametric amplifiers, and widely detuned photon-pair sources. Apart from compensating dispersion, the proposed mechanism can alternatively be utilized in an otherwise dispersionless resonator to counteract the detuning effect of self- and cross-phase modulation on the pump resonance during FWM, thereby addressing a fundamental issue in the performance of light sources such as broadband optical frequency combs.

  2. Two-photon resonances in femtosecond time-resolved four-wave mixing spectroscopy: {beta}-carotene

    SciTech Connect

    Namboodiri, V.; Namboodiri, M.; Flachenecker, G.; Materny, A.

    2010-08-07

    Femtosecond time-resolved pump-degenerate four-wave mixing (pump-DFWM) spectroscopy has been used to study the ultrafast dynamics of {beta}-carotene involving several electronic and vibrational states. An initial pump pulse, resonant with the S{sub 0}-to-S{sub 2} transition, excites the molecular system and a DFWM process, resonant with the S{sub 1}-to-S{sub n} transition, is used to probe the relaxation pathways. The transient shows a peculiar decay behavior, which is due to the contributions of resonant DFWM signal of the excited S{sub 1} state, nonresonant DFWM signal of the ground S{sub 0} state and vibrational hot S{sub 0}{sup *} state, and the two-photon resonant DFWM signal of the ground S{sub 0} state. We have used a kinetic model including all the signal contributions to successfully fit the transient. The time constants extracted are in very good agreement with the known values for {beta}-carotene. For comparison, a two-pulse pump-probe experiment was performed measuring the transient absorption at the wavelength of the DFWM experiment.

  3. Generation of optical frequency combs via four-wave mixing processes for low- and medium-resolution astronomy

    NASA Astrophysics Data System (ADS)

    Zajnulina, M.; Boggio, J. M. Chavez; Böhm, M.; Rieznik, A. A.; Fremberg, T.; Haynes, R.; Roth, M. M.

    2015-07-01

    We investigate the generation of optical frequency combs through a cascade of four-wave mixing processes in nonlinear fibres with optimised parameters. The initial optical field consists of two continuous-wave lasers with frequency separation larger than 40 GHz (312.7 pm at 1531 nm). It propagates through three nonlinear fibres. The first fibre serves to pulse shape the initial sinusoidal-square pulse, while a strong pulse compression down to sub-100 fs takes place in the second fibre which is an amplifying erbium-doped fibre. The last stage is a low-dispersion highly nonlinear fibre where the frequency comb bandwidth is increased and the line intensity is equalised. We model this system using the generalised nonlinear Schrödinger equation and investigate it in terms of fibre lengths, fibre dispersion, laser frequency separation and input powers with the aim to minimise the frequency comb noise. With the support of the numerical results, a frequency comb is experimentally generated, first in the near infra-red and then it is frequency-doubled into the visible spectral range. Using a MUSE-type spectrograph, we evaluate the comb performance for astronomical wavelength calibration in terms of equidistancy of the comb lines and their stability.

  4. Realisation of four-wave mixing phase matching for frequency components at intracavity stimulated Raman scattering in a calcite crystal

    SciTech Connect

    Smetanin, Sergei N; Fedin, Aleksandr V; Shurygin, Anton S

    2013-06-30

    The possibilities of implementing four-wave mixing (FWM) phase matching at stimulated Raman scattering (SRS) in a birefringent SRS-active crystal placed in a cavity with highly reflecting mirrors have been theoretically and experimentally investigated. Phase-matching angles providing conditions for five types of phase matching are determined for a calcite crystal. These types are characterised by different combinations of polarisation directions for the interacting waves and ensure FWM generation of either an anti-Stokes wave or the second Stokes SRS component. In agreement with the calculation results, low-threshold generation of the second Stokes SRS component with a wavelength 0.602 {mu}m was observed at angles of incidence on a calcite crystal of 4.8 Degree-Sign and 18.2 Degree-Sign , under SRS pumping at a wavelength of 0.532 {mu}m. This generation is due to the FWM coupling of the first and second Stokes SRS components with the SRS-pump wave. (nonlinear optical phenomena)

  5. Synthesis, z-scan and degenerate four wave mixing characterization of certain functionalized photosensitive polyesters containing ortho-hydroxyazo chromophores

    NASA Astrophysics Data System (ADS)

    Jayakrishnan, K.; Siji Narendran, N. K.; Sreejith, P.; Joseph, Antony; Chandrasekharan, K.; Purushothaman, E.

    2015-07-01

    The preparation and NLO characterization of photosensitive polyesters containing azoaromatic residues in the molecular backbone, functionalized with orthohydroxy chromophores is presented. Samples were studied for its UV-vis absorption, FT-IR and intensity dependent nonlinear absorption properties. Nonlinear characterization was carried out with z-scan using frequency doubled, Q-switched Nd:YAG laser operating at 532 nm. The closed aperture z-scan spectra reveal the self defocusing effects of the samples with negative nonlinearity coefficient (n2) showing values as high as -1.28 × 10-10 (esu) for certain samples and the corresponding third order susceptibility coefficient of the order of 29.9 × 10-12 (esu). Degenerate four wave mixing technique was employed to substantiate the findings. The numerical fits show that the molecules exhibit reverse saturable absorption. A study of beam fluence dependence of nonlinear absorption coefficient (βeff) has been presented. All phenomena indicate that molecules are reverse saturable absorbers whose optical limiting property gets enhanced with increasing conjugation length.

  6. Spectrally-isolated violet to blue wavelength generation by cascaded degenerate four-wave mixing in a photonic crystal fiber.

    PubMed

    Yuan, Jinhui; Kang, Zhe; Li, Feng; Zhang, Xianting; Zhou, Guiyao; Sang, Xinzhu; Wu, Qiang; Yan, Binbin; Zhou, Xian; Wang, Liang; Zhong, Kangping; Wang, Kuiru; Yu, Chongxiu; Tam, Hwa Yaw; Wai, P K A

    2016-06-01

    Generation of spectrally-isolated wavelengths in the violet to blue region based on cascaded degenerate four-wave mixing (FWM) is experimentally demonstrated for the first time in a tailor-made photonic crystal fiber, which has two adjacent zero dispersion wavelengths (ZDWs) at 696 and 852 nm in the fundamental mode. The influences of the wavelength λp and the input average power Pav of the femtosecond pump pulses on the phase-matched frequency conversion process are studied. When femtosecond pump pulses at λp of 880, 870, and 860 nm and Pav of 500 mW are coupled into the normal dispersion region close to the second ZDW, the first anti-Stokes waves generated near the first ZDW act as a secondary pump for the next FWM process. The conversion efficiency ηas2 of the second anti-Stokes waves, which are generated at the violet to blue wavelengths of 430, 456, and 472 nm, are 4.8, 6.48, and 9.66%, for λp equalling 880, 870, and 860 nm, respectively.

  7. Characterization of a deep-level compensation ratio through picosecond four-wave mixing on a transient reflection grating

    NASA Astrophysics Data System (ADS)

    Kadys, A.; Delaye, Ph; Roosen, G.; Jarasiunas, K.

    2007-09-01

    We demonstrate a novel application of a time-resolved four-wave mixing technique for the determination of a deep-level compensation ratio in a semi-insulating crystal. The approach is based on photoexcitation of carriers from deep impurity levels, formation of a space-charge electric field in deep traps, and monitoring dynamics of photorefractive, free- carrier and absorption gratings by light diffraction. The analysis of anisotropic diffraction features on the reflection grating provided requirements for crystal orientation in order to discriminate contribution of amplitude grating from the photorefractive phase grating, both being related to deep-trap occupation. Contributions of these optical nonlinearities were studied experimentally in (0 0 1)-oriented GaAs wafers by using a transient reflection grating configuration with a very small grating period (150 nm). Comparison of the reflection grating picosecond kinetics and its diffraction efficiency with modeling curves allowed us to ascribe the slow decay component to amplitude grating in recharged deep traps and determine their compensation ratio. The proposed technique allowed the determination of the compensation ratio of a deep EL2 donor, equal to 0.6 ± 0.05 in the given GaAs crystal.

  8. Four-wave mixing based light sources for real-world biomedical applications of coherent Raman microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Stimulated Raman Scattering requires an extremely quiet, widely wavelength tunable laser, which, up to now, is unheard of in fiber lasers. We present a compact and maintenance-free optical parametric oscillator based on degenerate four-wave mixing in a photonic crystal fiber. By employing an all-fiber frequency and repetition rate tunable laser as a seed source, we are able to generate tunable light between 1015 and 1065 nm. After amplification and subsequent conversion in the fiber OPO, signal and idler radiation between 785 and 960 nm and 1177 and 1500 nm may be generated with a repetition rate of 9 MHz. Therefore, we are able to address Raman shifts between 910 and 3030 cm-1. An additional output provides the Stokes radiation at 18 MHz required for the SRS process, which is passively synchronized to the tunable radiation. We measure the relative intensity noise of the Stokes beam at 9 MHz to be -150 dBc enabling high speed SRS imaging with a good signal-to-noise ratio. The combination of FWM based conversion, coupled with all-fiber Yb-based fiber lasers allows for the first turn-key, widely tunable and extremely compact laser systems developed for applications of CRS microscopy in clinics. This source could very well be the missing key instrument that CRS imaging requires for its real world transition.

  9. High Efficiency Four-Wave Mixing with Relaxation Coupling of Longitude-Optical Phonons in Semiconductor Quantum Wells

    NASA Astrophysics Data System (ADS)

    She, Yan-Chao; Zheng, Xue-Jun; Wang, Deng-Long; Ding, Jian-Wen

    2015-05-01

    The time-dependent analysis of four-wave mixing (FWM) has been performed in four-level double semiconductor quantum wells (SQWs) considering the cross-coupling of the longitude-optical phonons (LOP) relaxation. It is shown that both the amplitude and the conversion efficiency of the FWM field enhance greatly with the increasing strength of cross-coupling of LOP relaxation. Interestingly, a double peak value of the conversion efficiency is obtained under a relatively weak single-photon detuning considering the LOP coupling. When the detuning becomes stronger, the double peaks turn into one peak appearing at the line respect to the about equality two control fields. The results can be interpreted by the effect of electromagnetically induced transparency and the indirect transition. Such controlled high efficiency FWM based on the cross-coupling LOP may have potential applications in quantum control and communications. Supported by Program for Changjiang Scholars and Innovative Research Team in University under Grant (IRT1080), National Natural Science Foundation of China under Grant Nos. 51272158, 11374252, and 51372214, Changjiang Scholar Incentive Program under Grant No. [2009] 17, Scientific Research Fund of Hunan Provincial Education Department of China under Grant No. 12A140, the Science and Technology Foundation of Guizhou Province of China under Grant No. J20122314

  10. Direct generation of graphene plasmonic polaritons at THz frequencies via four wave mixing in the hybrid graphene sheets waveguides.

    PubMed

    Sun, Yu; Qiao, Guofu; Sun, Guodong

    2014-11-17

    A compact waveguide incorporating a high-index nano-ridge sandwiched between graphene sheets is proposed for the direct generation of graphene plasmonic polaritons (GSPs) via four wave mixing (FWM). The proposed waveguide supports GSP modes at the THz frequencies and photonic modes at the infrared wavelengths. Due to the strong confinement of coupled graphene sheets, the GSP modes concentrate in the high-index nano-ridge far below the diffraction limit, which improves integral overlap with the photonic modes and greatly facilitates the FWM process. To cope with the ultra-high effective refractive of the GSP modes, an alternative energy conservation diagram is selected for the degenerated FWM, which corresponds to one pump photon transfers its energy to two signal photons and one GSP photon. The single mode condition of the generated symmetric GSP modes is analyzed by the effective index method to suppress the undesired conversion. Due to the unique tunability of GSPs, the phase matching condition can be satisfied by tuning the chemical potential of the graphene sheets employing external gates. The FWM pumped at 1,550 nm with a peak power of 1 kW is theoretically investigated by solving the modified coupled mode equations. The generated GSP power reaches its maximum up to 67 W at a propagation distance of only 43.7 μm. The proposed waveguide have a great potential for integrated chip-scale GSP source.

  11. Polarization rotation of light propagating through a medium with efficient four-wave mixing and cross-phase modulation

    NASA Astrophysics Data System (ADS)

    Sahoo, Sushree S.; Bhowmick, Arup; Mohapatra, Ashok K.

    2017-03-01

    We have studied the rotation of an elliptically polarized light propagating through thermal rubidium vapor with efficient four-wave mixing (FWM) and cross-phase modulation (XPM). These nonlinear processes are enhanced by Zeeman coherence within the degenerate sub-levels of the two-level atomic system. The elliptically polarized light with small ellipticity is considered as the superposition of a strong-linearly-polarized pump beam and a weak-orthogonal-polarized probe beam. The interference of the probe and the newly generated light field due to degenerate FWM and their gain in the medium due to a large XPM induced by the pump beam leads to the rotation of the elliptical polarized light. A theoretical analysis of the probe propagation through the nonlinear medium was used to explain the experimental observation and the fitting of the experimental data gives the estimates of the third-order non-linear susceptibilities associated with FWM and XPM. Our study can provide useful parameters for the generation of efficient squeezed vacuum states and squeezed polarization states of light. Furthermore our study finds application in controlling the diffraction of a linearly-polarized light beam traversing the medium.

  12. Phase correlation between four-wave mixing and optical fields in double Λ-type atomic system.

    PubMed

    Jeong, Taek; Moon, Han Seb

    2016-12-12

    We study the spectral features and phase of four-wave mixing (FWM) light according to the relative phase-noise of the optical fields coupled to a double Λ-type atomic system of the 5S1/2-5P1/2 transition of 87Rb atoms. We observe that the spectral shape of the FWM spectrum is identical to that of the two-photon absorption (TPA) spectrum due to two-photon coherence and that it is independent of the relative phase-noise of the pump light. From these results, we clarify that the two-photon coherence plays a very important role in the FWM process. Furthermore, we measure the relative linewidth of the FWM signal to the probe and pump lasers by means of a beat interferometer. We confirmed that the phase of the FWM signal is strongly correlated with that of the pump laser under the condition of phase-locked probe and coupling lasers for two-photon coherence.

  13. Single-step fabrication of scalable multimode quantum resources using four-wave mixing with a spatially structured pump

    NASA Astrophysics Data System (ADS)

    Wang, Hailong; Fabre, Claude; Jing, Jietai

    2017-05-01

    Multimode quantum resources or states, in which quantum correlations are shared and distributed among multiple parties, are important not only for fundamental tests of quantum effects but also for their numerous possible applications in quantum technologies, such as quantum imaging and quantum metrology. Here we demonstrate the single-step fabrication of a multimode quantum resource from four-wave mixing (FWM) process in hot Rb vapor using a spatially structured pump, which consists of a coherent combination of two tilted pump beams. During this FWM process, one probe beam is amplified, three conjugate and two new probe beams are generated. The measured degrees of the intensity squeezing for the four-beam case and six-beam case are around -4.1 ±0.1 dB and -4.7 ±0.1 dB, respectively. The generated multiple quantum correlated beams are naturally separated with distinct directions, which is crucial for sending them out to quantum nodes at different locations in quantum communication. Our scheme is compact, simple, phase insensitive, and easily scalable to larger number of quantum-correlated modes.

  14. Flat and broadband supercontinuum generation by four-wave mixing in a highly nonlinear tapered microstructured fiber.

    PubMed

    Liao, Meisong; Gao, Weiqing; Cheng, Tonglei; Duan, Zhongchao; Xue, Xiaojie; Suzuki, Takenobu; Ohishi, Yasutake

    2012-12-10

    We have demonstrated broad supercontinuum (SC) generation by using a highly nonlinear tapered tellurite microstructured fiber pumped by a 15-ps-pulsed laser with the peak power of 375 W. The fiber is characterized with a short section with a large diameter followed by a long section with a small diameter. The SC was mainly generated in the last 30-cm-long section which had a core diameter of 0.9 μm and a zero dispersion wavelength around the pump wavelength. Such a core size and a dispersion profile were chosen to ensure the SC was mainly broadened by phase matched four-wave mixing. The SC spans from UV to mid IR. The 10 dB spectrum is from 780 to 1890 nm. The input peak power is much lower than conventionally adopted in the picosecond regime. The constructed SC light source is cost-effective, since neither femtosecond pulsed laser nor high power picosecond pulsed laser is adopted.

  15. Determination of the electric field strength of filamentary DBDs by CARS-based four-wave mixing

    NASA Astrophysics Data System (ADS)

    Böhm, P.; Kettlitz, M.; Brandenburg, R.; Höft, H.; Czarnetzki, U.

    2016-10-01

    It is demonstrated that a four-wave mixing technique based on coherent anti-Stokes Raman spectroscopy (CARS) can determine the electric field strength of a pulsed-driven filamentary dielectric barrier discharge (DBD) of 1 mm gap, using hydrogen as a tracer medium in nitrogen at atmospheric pressure. The measurements are presented for a hydrogen admixture of 10%, but even 5% H2 admixture delivers sufficient infrared signals. The lasers do not affect the discharge by photoionization or by other radiation-induced processes. The absolute values of the electric field strength can be determined by the calibration of the CARS setup with high voltage amplitudes below the ignition threshold of the arrangement. This procedure also enables the determination of the applied breakdown voltage. The alteration of the electric field is observed during the internal polarity reversal and the breakdown process. One advantage of the CARS technique over emission-based methods is that it can be used independently of emission, e.g. in the pre-phase and in between two consecutive discharges, where no emission occurs at all.

  16. Re-Visiting the Electronic Energy Map of the Copper Dimer by Double-Resonant Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Visser, Bradley; Bornhauser, Peter; Beck, Martin; Knopp, Gregor; Marquardt, Roberto; Gourlaouen, Christophe; van Bokhoven, Jeroen A.; Radi, Peter

    2017-06-01

    The copper dimer is one of the most studied transition metal (TM) diatomics due to its alkali-metal like electronic shell structure, strongly bound ground state and chemical reactivity. The high electronic promotion energy in the copper atom yields numerous low-lying electronic states compared to TM dimers with d)-hole electronic configurations. Thus, through extensive study the excited electronic structure of Cu_2 is relatively well known, however in practice few excited states have been investigated with rotational resolution or even assigned term symbols or dissociation limits. The spectroscopic methods that have been used to investigate the copper dimer until now have not possessed sufficient spectral selectivity, which has complicated the analysis of the often overlapping transitions. Resonant four-wave mixing is a non-linear absorption based spectroscopic method. In favorable cases, the two-color version (TC-RFWM) enables purely optical mass selective spectral measurements in a mixed molecular beam. Additionally, by labelling individual rotational levels in the common intermediate state the spectra are dramatically simplified. In this work, we report on the rotationally resolved characterization of low-lying electronic states of dicopper. Several term symbols have been assigned unambiguously. De-perturbation studies performed shed light on the complex electronic structure of the molecule. Furthermore, a new low-lying electronic state of Cu_2 is discovered and has important implications for the high-level theoretical structure calculations performed in parallel. In fact, the ab initio methods applied yield relative energies among the electronic levels that are almost quantitative and allow assignment of the newly observed state that is governed by spin-orbit interacting levels.

  17. Detection and Interpretation of Collisional Transfer and Rotational Anisotropy Fingerprints in Resonant Four-Wave Mixing Spectra.

    NASA Astrophysics Data System (ADS)

    Kouzov, A.; Radi, P.; Maksyutenko, P.; Kozlov, D.

    2013-06-01

    Coherent responses produced by resonant four-wave mixing (RFWM) in a weakly absorbing medium carry valuable information on the intrinsic properties and dynamics of the quantum states involved. Here, two aspects of RFWM applications are highlighted. First, the Two-Color (TC) version of RFWM was found to be a unique spectroscopic tool to directly trace collisional state-to-state transfer in isotropic gaseous media, both in the frequency% and time domains. Second, the RFWM techniques appeared to be very useful for studies of the rotational anisotropy. Here we report new experimental one-color RFWM spectra of the OH radicals produced by laser photolysis of H_{2}O_{2} at 266 nm. Polarization dependence and Doppler line structure of the spectra show clear evidence of the pronounced anisotropy of angular momentum (j) and velocity (% v) distributions as well as on the j-v correlation. The obtained results directly point to the pronounced OH helicity (i.e. j% ∥ v) which yet remained beyound the reach of purely optical means. For all mentioned cases, the line-shape theory is an optimal tool to derive compact expressions for the RFWM signals. The work was supported by the Swiss Federal Office of Energy, the Swiss National Science Foundation (200020_124542/1), and by the Russian Foundation for Basic Research, grants 11-02-01296 and 11-03-00448. P. P. Radi, H.-M. Frey, B. Mischler, A. P. Tzannis, P. Beaud, and T. Gerber, Chem. Phys. Lett. 265, 271 (1997). X. Chen and T. B. Settersten, Appl. Opt. 46, 3911 (2007). T. A. W. Wasserman, P. H. Vaccaro, and B. R. Johnson, J. Chem. Phys. 106, 6314 (1997). A.P. Kouzov and P.P. Radi, Phys. Rev. A 63, 010701 (2000).

  18. Probe gain via four-wave mixing based on spontaneously generated coherence

    NASA Astrophysics Data System (ADS)

    Yang, Hong; Zhang, Ting-gui; Zhang, Yan

    2017-02-01

    Not Available Project supported by the Natural Science Foundation of Hainan Province, China (Grant Nos. 20151005, 20151015, and 20161006), the National Natural Science Foundation of China (Grant Nos. 11247005, 51262007, 11501153, and 41564006), the Postdoctoral Scientific Research Program of Jilin Province, China (Grant No. RB201330), the Project Sponsored by Science Research Foundation for Returned Overseas Chinese Scholars, and the Fundamental Research Funds for the Central Universities, China (Grant No. 12QNJJ006).

  19. Electronic spectra of radicals in a supersonic slit-jet discharge by degenerate and two-color four-wave mixing.

    PubMed

    Mazzotti, Fabio J; Achkasova, Elena; Chauhan, Richa; Tulej, Marek; Radi, Peter P; Maier, John P

    2008-01-07

    Four-wave mixing techniques have been used for the measurement of electronic transitions of cold transient species generated in a supersonic slit-jet discharge expansion. The origin band of the d(3)Pi(g)-a(3)Pi(u) system of C(2) and A(2)Pi(3/2)-X[combining tilde](2)Pi(3/2) electronic transition of HC(4)S were recorded. A signal-to-noise ratio of 10(4) in the spectra was achieved, resulting in detection limits of 10(10) cm(-3) for these two molecules. Application of selective two-color resonant four-wave mixing is used for the spectral assignment utilizing the double-resonance nature of the method. The combination of these techniques with a slit source proves to be a sensitive approach for the detection of transient molecules in a molecular beam discharge.

  20. Selective detection of radicals and ions in a slit-jet discharge by degenerate and two-color four-wave mixing.

    PubMed

    Raghunandan, Ranjini; Mazzotti, Fabio J; Chauhan, Richa; Tulej, Marek; Maier, John P

    2009-11-26

    Degenerate four-wave mixing (DFWM) was used to record the spectra of charged and neutral carbon-containing radicals generated in a pulsed discharge source within a supersonic slit-jet expansion. Detection limits of approximately 10(9) molecules cm(-3) are achieved. The DFWM method allows a selective molecular detection by varying the discharge timings. Increased spectral selectivity is obtained by applying the two-color, doubly resonant four-wave mixing variant. This shows the potential of the techniques for sensitive and selective spectral analysis of radicals in discharges. The methods are successfully used for the detection of C(4)H, HC(2)S, and HC(4)H(+) with signal-to-noise in the range of 10(2)-10(4).

  1. Multi-wavelength Erbium-doped fiber laser based on four-wave-mixing effect in single mode fiber and high nonlinear fiber.

    PubMed

    Wang, Pinghe; Weng, Danmei; Li, Kun; Liu, Yong; Yu, Xuecai; Zhou, Xiaojun

    2013-05-20

    A multi-wavelength Erbium-doped fiber (EDF) laser based on four-wave-mixing is proposed and experimentally demonstrated. The 5 km single mode fiber in the cavity enhances the four-wave-mixing to suppress the homogenous broadening of the erbium-doped fiber and get the stable multi-wavelength comb. The lasing stability is investigated. When the pump power is 300 mW, the fiber laser has 5-lasing lines and the maximum fluctuation of the output power is about 3.18 dB. At the same time, a laser with 110 m high nonlinear fiber (HNFL) is demonstrated. When the pump power is 300 mW, it has 7-lasing lines (above -30 dBm) and the maximum fluctuation is 0.18dB.

  2. Bandwidth scaling and spectral flatness enhancement of optical frequency combs from phase-modulated continuous-wave lasers using cascaded four-wave mixing.

    PubMed

    Supradeepa, V R; Weiner, Andrew M

    2012-08-01

    We introduce a new cascaded four-wave mixing technique that scales up the bandwidth of frequency combs generated by phase modulation of a continuous-wave (CW) laser while simultaneously enhancing the spectral flatness. As a result, we demonstrate a 10 GHz frequency comb with over 100 lines in a 10 dB bandwidth in which a record 75 lines are within a flatness of 1 dB. The cascaded four-wave mixing process increases the bandwidth of the initial comb generated by the modulation of a CW laser by a factor of five. The broadband comb has approximately quadratic spectral phase, which is compensated upon propagation in single-mode fiber, resulting in a 10 GHz train of 940 fs pulses.

  3. Optical phase conjugation by four-wave mixing in Nd:YAG laser oscillator for optical energy transfer to a remote target

    NASA Astrophysics Data System (ADS)

    Kawakami, K.; Okamura, H.; Komurasaki, K.

    2015-02-01

    A self-starting phase conjugator was designed for optical energy transfer to a remote target. Saturable-gain four-wave mixing in a laser resonator was achieved using a flash-lamp pumped Nd:YAG crystal and phase-conjugate light (PCL) generation were verified. Wavefront correction experimentation revealed that beam wander caused by air turbulence is compensated. Tracking capability was demonstrated in the range of 9 mrad with tracking accuracy of ±0.04 mrad. The maximum field of view was measured to be 4.7°. Dependence of phase-conjugate light energy on reference light energy was investigated. The maximum output of 320 mJ was obtained. The temporal behavior of PCL is discussed based on the four-wave mixing mechanism. Unlike a conventional loop resonator type phase conjugator, this system is applicable for wireless energy transfer to a remote target.

  4. Generation of femtosecond anti-stokes pulses through phase-matched parametric four-wave mixing in a photonic crystal fiber.

    PubMed

    Konorov, S O; Serebryannikov, E E; Zheltikov, A M; Zhou, Ping; Tarasevitch, A P; von der Linde, D

    2004-07-01

    Phase-matched parametric four-wave mixing in higher-order guided modes of a photonic crystal fiber is shown to result in an efficient decay of 40-fs 800-nm Ti:sapphire laser pump pulses into an anti-Stokes signal with a central wavelength around 590-600 nm and a Stokes signal centered at 1.25 microm. The photonic crystal fiber is designed in such a way as to minimize the group-velocity dispersion at the pump wavelength, phase match the parametric four-wave-mixing process, and reduce the group delay between the pump and the anti-Stokes pulses. The duration of the anti-Stokes pulse under these conditions, as shown by cross-correlation frequency-resolved optical gating measurements, is less than 200 fs.

  5. Optical phase conjugation by four-wave mixing in Nd:YAG laser oscillator for optical energy transfer to a remote target

    SciTech Connect

    Kawakami, K. Komurasaki, K.; Okamura, H.

    2015-02-28

    A self-starting phase conjugator was designed for optical energy transfer to a remote target. Saturable-gain four-wave mixing in a laser resonator was achieved using a flash-lamp pumped Nd:YAG crystal and phase-conjugate light (PCL) generation were verified. Wavefront correction experimentation revealed that beam wander caused by air turbulence is compensated. Tracking capability was demonstrated in the range of 9 mrad with tracking accuracy of ±0.04 mrad. The maximum field of view was measured to be 4.7°. Dependence of phase-conjugate light energy on reference light energy was investigated. The maximum output of 320 mJ was obtained. The temporal behavior of PCL is discussed based on the four-wave mixing mechanism. Unlike a conventional loop resonator type phase conjugator, this system is applicable for wireless energy transfer to a remote target.

  6. Spectral phase transfer from near IR to deep UV by broadband phase-matched four-wave mixing in an argon-filled hollow core waveguide

    NASA Astrophysics Data System (ADS)

    Siqueira, J. P.; Mendonça, C. R.; Zilio, S. C.; Misoguti, L.

    2016-10-01

    We report on the implementation of a spectral phase transfer scheme from near IR to deep UV, in which the frequency conversion step is based on the broadband phase-matched four-wave mixing in a gas-filled hollow core waveguide. Micro joule level femtosecond pulses at 260 nm were generated by nonlinear mixing of a Ti:sapphire laser and its second-harmonic. The transfer of a π-step phase in a controllable manner was proposed and confirmed by a modulation observed in the generated deep UV femtosecond pulse spectrum due to an interference process. Numerical simulations confirmed our results.

  7. Electrically Tunable Microlens via Photopolymerization-Induced Phase Separation of Liquid Crystal/Monomer Mixtures Based on Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Kyu, Thein; Nwabunma, Domasius

    2001-03-01

    We introduce a new method of fabricating electrically tunable liquid crystal (LC) microlens via photopolymerization-induced phase separation of LC/monomer mixtures using four-wave mixing technique, i.e., interference of two horizontal and two vertical waves. The microlens forming process was simulated based on a spatially modulated photopolymerization reaction coupled with the time-dependent Ginzburg-Landau (TDGL) Model C equations, which incorporate free energy densities due to isotropic mixing, LC ordering, and polymer network elasticity. Our simulation revealed that the calculated LC microlens are similar to the compound eyes found in the eyes of insects such as flies, ants, and wasps.

  8. Phase-matched waveguide four-wave mixing scaled to higher peak powers with large-core-area hollow photonic-crystal fibers.

    PubMed

    Konorov, S O; Serebryannikov, E E; Fedotov, A B; Miles, R B; Zheltikov, A M

    2005-05-01

    Hollow photonic-crystal fibers with large core diameters are shown to allow waveguide nonlinear-optical interactions to be scaled to higher pulse peak powers. Phase-matched four-wave mixing is predicted theoretically and demonstrated experimentally for millijoule nanosecond pulses propagating in a hollow photonic-crystal fiber with a core diameter of about 50 microm , suggesting the way to substantially enhance the efficiency of nonlinear-optical spectral transformations and wave mixing of high-power laser pulses in the gas phase.

  9. Generation of sub-two-cycle mid-infrared pulses by four-wave mixing through filamentation in air.

    PubMed

    Fuji, Takao; Suzuki, Toshinori

    2007-11-15

    Generation of sub-two-cycle, microjoule pulses in the mid-infrared region is demonstrated. Fundamental and second-harmonic pulses of 25 fs Ti:sapphire amplifier output were focused into the air to produce extremely broadband mid-infrared pulses by four-wave difference-frequency generation through the filamentation. The full width at half-maximum of the spectral bandwidth reaches one octave (2.5-5.5 microm), which is sufficiently broad for sub-single-cycle pulse generation. The pulse width was estimated to be 13 fs, without any compressors, by cross-correlation frequency resolved optical gating. The output energy of more than a few microjoule is sufficient for spectroscopy.

  10. Effect of the coherent cancellation of the two-photon resonance on the generation of vacuum ultraviolet light by two-photon reasonantly enhanced four-wave mixing

    SciTech Connect

    Payne, M.G.; Garrett, W.R.; Judish, J.P.; Wunderlich, R.

    1988-11-01

    Many of the most impressive demonstrations of the efficient generation of vacuum ultraviolet (VUV) light have made use of two- photon resonantly enhanced four-wave mixing to generate light at ..omega../sub VUV/ = 2..omega../sub L1/ +- ..omega../sub L2/. The two-photon resonance state is coupled to the ground state both by two photons from the first laser, or by a photon from the second laser and one from the generated VUV beam. We show here that these two coherent pathways destructively interfere once the second laser is made sufficiently intense, thereby leading to an important limiting effect on the achievable conversion efficiency. 4 refs.

  11. Broad optical bandwidth based on nonlinear effect of intensity and phase modulators through intense four-wave mixing in photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Eltaif, Tawfig

    2017-05-01

    This work investigates the advantages of nonlinear optics of a cascaded intensity modulator (IM) and phase modulator (PM) to generate an initial optical frequency comb. The results show that when the direct current bias to amplitude ratio, α=0.1, and the IM and PM have the same modulation index and are equal 10, seed comb is achieved; it is generated by the modulation of two continuous wave lasers. Hence, based on these parameters, an intense four-wave mixing is created through 9 m of photonic crystal fiber. Moreover, a broadband spectrum was achieved, spaced by a 30-GHz microwave frequency.

  12. Chalcogenide As2S3 suspended core fiber for mid-IR wavelength conversion based on degenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Szpulak, M.; Février, Sébastien

    2009-05-01

    A chalcogenide optical fiber of special design is proposed to convert a short-wavelength IR radiation (around 2 μm) up to second transparency window of atmospheric air (around 4.5 μm) by degenerate four-wave mixing. The fiber supports a small core surrounded by three large air holes. The zero-dispersion wavelength is shifted down to 2 μm in this fiber by properly tailoring geometry of the fiber core. We demonstrate by solving the nonlinear Schrödinger equation that efficient wavelength-conversion can be obtained by pumping the fiber with a Tm:SiO2 pulsed fiber laser.

  13. Wideband multiwavelength output generation based on cascaded four-wave mixing in distributed Raman amplifier utilizing a Fabry-Pérot laser diode

    NASA Astrophysics Data System (ADS)

    Al-Alimi, A. W.; Cholan, N. A.; Yaacob, M. H.; Mahdi, M. A.

    2017-08-01

    Multiwavelength output generation based on cascaded four-wave mixing in a distributed Raman amplifier is demonstrated experimentally. The technique consists of launching a probe signal and Fabry-Pérot pump source in a co-propagating setup into a 2 km length of highly nonlinear fiber. In this configuration, the Fabry-Pérot laser diode plays two roles; as a Raman pump and as a source for multiple wavelengths generation. The output of multiple wavelengths with 27.8 GHz spacing centered around the probe signal is generated over 43 nm operation bandwidth. Besides, the bandwidth of the multiwavelength spectrum is also investigated at different wavelength ranges.

  14. Synthesis of optical standard frequencies in the S, C and L telecommunication bands by use of four-wave mixing in semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Carrasco-Sanz, Ana; Martín-López, Sonia; González-Herráez, Miguel; Corredera, Pedro; Hernanz, María Luisa

    2006-08-01

    The generation of standard reference frequencies close to the ITU channels is essential for the calibration and maintenance of DWDM systems. This work describes a method to synthesize frequency references in the range from 187.1 to 205.1 THz (1462-1602 nm). The method is based on the generation of four equispaced frequencies (by the process of four-wave mixing in a semiconductor amplifier) of which two are locked to absorption lines of the acetylene 12C 2H 2 (1511-1542 nm).

  15. Four-wave mixing based widely tunable wavelength conversion using 1-m dispersion-shifted bismuth-oxide photonic crystal fiber.

    PubMed

    Chow, K K; Kikuchi, K; Nagashima, T; Hasegawa, T; Ohara, S; Sugimoto, N

    2007-11-12

    We demonstrate widely tunable wavelength conversion based on four-wave mixing using a dispersion-shifted bismuth-oxide photonic crystal fiber (Bi-PCF). A 1-meter-long Bi-PCF is used as the nonlinear medium for wavelength conversion of a 10 Gb/s non-return-to-zero (NRZ) signal. A 3- dB working range of the converted signal over 35 nm is obtained with around 1-dB power penalty in the bit-error-rate measurements.

  16. Comparative analysis of four-wave mixing of optical pulses in slow- and fast-light regimes of a silicon photonic crystal waveguide.

    PubMed

    Lavdas, Spyros; Panoiu, Nicolae C

    2015-09-15

    We present an in-depth study of four-wave mixing (FWM) of optical pulses in silicon photonic crystal waveguides. Our analysis is based on a rigorous model that includes all relevant linear and nonlinear optical effects and their dependence on the group velocity, as well as the influence of free carriers on pulse dynamics. In particular, we reveal key differences between FWM in the slow- and fast-light regimes and how they are related to the physical parameters of the pulses and waveguide. Finally, we illustrate how these results can be used to design waveguides with optimized FWM conversion efficiency.

  17. Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    NASA Astrophysics Data System (ADS)

    Louchev, Oleg A.; Bakule, Pavel; Saito, Norihito; Wada, Satoshi; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-01

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-α (Ly-α) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-α generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-α radiation generation can achieve a value of ˜5×10-4 which is restricted by the total combined absorption of the fundamental and generated radiation.

  18. The first search for sub-eV scalar fields via four-wave mixing at a quasi-parallel laser collider

    NASA Astrophysics Data System (ADS)

    Homma, Kensuke; Hasebe, Takashi; Kume, Kazuki

    2014-08-01

    A search for sub-eV scalar fields coupling to two photons has been performed via four-wave mixing at a quasi-parallel laser collider for the first time. The experiment demonstrates the novel approach of searching for resonantly produced sub-eV scalar fields by combining two-color laser fields in the vacuum. The aim of this paper is to provide the concrete experimental setup and the analysis method based on specific combinations of polarization states between incoming and outgoing photons, which is extendable to higher-intensity laser systems operated at high repetition rates. No significant signal of four-wave mixing was observed by combining a 0.2 μ J/0.75 ns pulse laser and a 2 mW CW laser on the same optical axis. Based on the prescription developed for this particular experimental approach, we obtained the upper limit at a confidence level of 95% on the coupling-mass relation.

  19. Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

    SciTech Connect

    Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi; Bakule, Pavel; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

    2011-09-15

    We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

  20. Optical bistability and four-wave mixing with a single nitrogen-vacancy center coupled to a photonic crystal nanocavity in the weak-coupling regime.

    PubMed

    Li, Jiahua; Yu, Rong; Ding, Chunling; Wu, Ying

    2014-06-16

    We explore optical bistability and degenerate four-wave mixing of a hybrid optical system composed of a photonic crystal nanocavity, a single nitrogen-vacancy center embedded in the cavity, and a nearby photonic waveguide serving for in- and outcoupling of light into the cavity in the weak-coupling regime. Here the hybrid system is coherently driven by a continuous-wave bichromatic laser field consisting of a strong control field and a weak probe field. We take account of the nonlinear nature of the nitrogen-vacancy center in the Heisenberg-Langevin equations and give an effective perturbation method to deal with such problems in the continuous-wave-operation regime. The results clearly show that the bistability region of the population inversion and the intensity of the generated four-wave mixing field can be well controlled by properly adjusting the system practical parameters. The nanophotonic platform can be used to implement our proposal. This investigation may be useful for gaining further insight into the properties of solid-state cavity quantum electrodynamics system and find applications in all-optical wavelength converter and switch in a photonic crystal platform.

  1. All-optical ultrafast wavelength and mode converter based on inter-modal four-wave mixing in few-mode fibers

    NASA Astrophysics Data System (ADS)

    Weng, Yi; He, Xuan; Wang, Junyi; Pan, Zhongqi

    2015-08-01

    An ultrafast all-optical simultaneous wavelength and mode conversion scheme is purposed based on intermodal four-wave mixing (IM-FWM), with the capability of switching state of polarization (SOP) and mode degeneracy orientation (MDO) in few-mode fibers (FMF). The relation among the conversion efficiency, pump power and phase matching conditions is investigated in theory analysis and simulation. Using this scheme, cross-polarization modulation (XPolM) and cross-mode modulation (XMM) can be achieved, by in the best case up to 50% conversion efficiency. Furthermore, numerical results further indicate that the proposed configuration has the potential application for generating doughnut modes by the mixing of three characteristic spatial frequencies.

  2. Carrier diffusion in thin-film CH3NH3PbI3 perovskite measured using four-wave mixing

    NASA Astrophysics Data System (ADS)

    Webber, D.; Clegg, C.; Mason, A. W.; March, S. A.; Hill, I. G.; Hall, K. C.

    2017-09-01

    We report the application of femtosecond four-wave mixing (FWM) to the study of carrier transport in solution-processed CH3NH3PbI3. The diffusion coefficient was extracted through direct detection of the lateral diffusion of carriers utilizing the transient grating technique, coupled with the simultaneous measurement of decay kinetics exploiting the versatility of the boxcar excitation beam geometry. The observation of the exponential decay of the transient grating versus interpulse delay indicates diffusive transport with negligible trapping within the first nanosecond following excitation. The in-plane transport geometry in our experiments enabled the diffusion length to be compared directly with the grain size, indicating that carriers move across multiple grain boundaries prior to recombination. Our experiments illustrate the broad utility of FWM spectroscopy for rapid characterization of macroscopic film transport properties.

  3. Non-degenerate four-wave mixing in an optically injection-locked InAs/InP quantum dot Fabry–Perot laser

    SciTech Connect

    Huang, H.; Schires, K.; Grillot, F.; Poole, P. J.

    2015-04-06

    Non-degenerate four-wave mixing in an InAs/InP quantum dot Fabry–Perot laser is investigated with an optical injection-locking scheme. Wavelength conversion is obtained for frequency detunings ranging from +2.5 THz to −3.5 THz. The normalized conversion efficiency is maintained above −40 dB between −1.5 and +0.5 THz with an optical signal-to-noise ratio above 20 dB and a maximal third-order nonlinear susceptibility normalized to material gain of 2 × 10{sup −19} m{sup 3}/V{sup 2}. In addition, we show that injection-locking at different positions in the gain spectrum has an impact on the nonlinear conversion process and the symmetry between up- and down- converted signals.

  4. QPSK-to-2×BPSK wavelength and modulation format conversion through phase-sensitive four-wave mixing in a highly nonlinear optical fiber.

    PubMed

    Da Ros, Francesco; Dalgaard, Kjeld; Lei, Lei; Xu, Jing; Peucheret, Christophe

    2013-11-18

    A phase-sensitive four-wave mixing (FWM) scheme enabling the simultaneous conversion of the two orthogonal quadratures of an optical signal to different wavelengths is demonstrated for the first time under dynamic operation using a highly nonlinear optical fiber (HNLF) as the nonlinear medium. The scheme is first optimized with respect to the power levels and phases of the four phase-coherent pumps. The successful modulation and wavelength conversion of the two complex quadratures of a quadrature phase-shift keying (QPSK) signal to two binary phase-shift keying (BPSK) signals is then demonstrated experimentally with no power penalty at a bit-error-ratio (BER) of 10(-9) compared to direct interferometric demodulation of the QPSK signal.

  5. Multi-band multiwavelength fiber laser based on the combined effects of four wave mixing and self-seeding stimulated Brillouin scattering

    NASA Astrophysics Data System (ADS)

    Yuan, Yijun; Yi, Miao; Yao, Yong

    2017-07-01

    A multi-band multiwavelength erbium-doped fiber laser (MBMEFL) based on the combined four wave mixing effect (FWM) and self-seeding stimulated Brillouin scattering (SSBS) effect has been studied experimentally. We use two ring cavities which consist of a large and a small cavity to build up this MBMEFL. The output multiple bands and multiple wavelengths are depended on the EDFA power and the length of the single mode fiber (SMF). With a proper length of SMF, we can achieve multi-band lasing by FWM effect and multiwavelength lasing in these bands by SSBS. By increasing the EDFA power, the multi-band multiwavelength lasing signals from the MBMEFL decrease.

  6. Broadband optical parametric amplifier formed by two pairs of adjacent four-wave mixing sidebands in a tellurite microstructured optical fibre

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Tuan, Tong-Hoang; Kawamura, Harutaka; Nagasaka, Kenshiro; Suzuki, Takenobu; Ohishi, Yasutake

    2016-05-01

    A broadband fibre-optical parametric amplifier (FOPA) operating at a novel wavelength region that is far from the pump wavelength has been demonstrated by exploiting two pairs of adjacent four-wave mixing (FWM) sidebands generated simultaneously in a tellurite microstructured optical fibre (TMOF). Owing to the large nonlinearity of the TMOF and the high pump peak power provided by a picosecond laser, a maximal average gain of 65.1 dB has been obtained. When the FOPA is operated in a saturated state, a flat-gain amplification from 1424 nm to 1459 nm can be achieved. This broadband and high-gain FOPA operating at new wavelength regions far from the pump offers the prospect of all-optical signal processing.

  7. Spectral broadening due to intra-cavity four-wave mixing at low pump powers in erbium-doped fiber ring laser

    NASA Astrophysics Data System (ADS)

    Suchita; Sarbadhikari, Soham; Vijaya, R.

    2014-02-01

    In this paper, we present the experimental results of multi-pump-induced four-wave mixing (FWM) in erbium-doped fiber ring laser (EDFRL) in the wavelength range of 1560-1600 nm. The required multiple pumps are generated within the ring cavity by an appropriate choice of the wavelength range of operation with a suitable length of erbium-doped fiber. By introducing the optical nonlinearity with specialty fibers such as the highly nonlinear fiber (HNLF) and dispersion shifted fiber (DSF), FWM processes occurring in the laser are studied at low powers of the pump laser at 980 nm. The prevalent FWM theory is improved to interpret the two-pump and four-pump-induced side band generation in the first- and second-orders, after including the effect of phase mismatch at the wavelengths used in the experiments.

  8. Simultaneous multichannel wavelength multicasting and XOR logic gate multicasting for three DPSK signals based on four-wave mixing in quantum-dot semiconductor optical amplifier.

    PubMed

    Qin, Jun; Lu, Guo-Wei; Sakamoto, Takahide; Akahane, Kouichi; Yamamoto, Naokatsu; Wang, Danshi; Wang, Cheng; Wang, Hongxiang; Zhang, Min; Kawanishi, Tetsuya; Ji, Yuefeng

    2014-12-01

    In this paper, we experimentally demonstrate simultaneous multichannel wavelength multicasting (MWM) and exclusive-OR logic gate multicasting (XOR-LGM) for three 10Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signals in quantum-dot semiconductor optical amplifier (QD-SOA) by exploiting the four-wave mixing (FWM) process. No additional pump is needed in the scheme. Through the interaction of the input three 10Gbps DPSK signal lights in QD-SOA, each channel is successfully multicasted to three wavelengths (1-to-3 for each), totally 3-to-9 MWM, and at the same time, three-output XOR-LGM is obtained at three different wavelengths. All the new generated channels are with a power penalty less than 1.2dB at a BER of 10(-9). Degenerate and non-degenerate FWM components are fully used in the experiment for data and logic multicasting.

  9. Performance investigation of suppression of four wave mixing using optical phase conjugation with different modulation format in DWDM soliton communication system

    NASA Astrophysics Data System (ADS)

    Kaur, G.; Kaler, R. S.; Singh, S.

    2017-03-01

    In this paper, the performance of dense wavelength division multiplexed (DWDM) soliton transmission system for return-to-zero (RZ) and non-return-to-zero (NRZ) modulation formats have been investigated. The main aim of this paper is to estimate and mitigate the four wave mixing (FWM) power by using in-line optical phase conjugator (OPC). The effect of FWM has been estimated using real fiber link having non-linear and attenuation losses. The FWM power is strongly suppressed by introducing destructive interference between the first and second halves of in-line OPC. It has been indicated that RZ with OPC yields the better performance with FWM power suppression (more than 20 dBm in certain cases) with reasonable bit error rate and Q-factor.

  10. Observation of the exciton and Urbach band tail in low-temperature-grown GaAs using four-wave mixing spectroscopy

    SciTech Connect

    Webber, D.; Yildirim, M.; Hacquebard, L.; March, S.; Mathew, R.; Gamouras, A.; Hall, K. C.; Liu, X.; Dobrowolska, M.; Furdyna, J. K.

    2014-11-03

    Four-wave mixing (FWM) spectroscopy reveals clear signatures associated with the exciton, free carrier inter-band transitions, and the Urbach band tail in low-temperature-grown GaAs, providing a direct measure of the effective band gap as well as insight into the influence of disorder on the electronic structure. The ability to detect (and resolve) these contributions, in contrast to linear spectroscopy, is due to an enhanced sensitivity of FWM to the optical joint density of states and to many-body effects. Our experiments demonstrate the power of FWM for studying the near-band-edge optical properties and coherent carrier dynamics in low-temperature-grown semiconductors.

  11. Effects of three-body interactions on the instabilities and self-oscillations of the four-wave mixing in Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Ngounga Makoundit, G. J.; Ekogo, T. B.; Moubissi, A. B.; Ben-Bolie, G. H.; Kofane, T. C.

    2017-08-01

    In this paper, we analyze and discuss instabilities and self-oscillations of four-wave mixing in two-component Bose-Einstein condensates with two- and three-body interatomic interactions. The model is very accurately described in the mean-field approximation by the cubic-quintic Gross-Pitaevskii equation. The relation between the input and output field intensities is multivalued and the effects of the quintic nonlinearity on the self-oscillations of the system are studied. We have also found that the magnitude of the signal beam increases with the increase of the intensity of the probe beam, up to a saturated value, then it decreases with the increase of the intensity of the probe beam. We have shown that the three-body interatomic interactions enhance this saturated value.

  12. Using the seventh-order numerical method to solve first-order nonlinear coupled-wave equations for degenerate two-wave and four-wave mixing

    NASA Astrophysics Data System (ADS)

    Ja, Y. H.

    1984-12-01

    Using a new seventh-order numerical method [the O(h 7) method] for solving two-point boundary value problems, numerical solutions of the first-order nonlinear coupledwave equations for degenerate two-wave and four-wave mixing in a reflection geometry have been obtained. A computer program employing the Gauss-Jordan elimination technique has also been adopted to effectively solve the resultant large, sparse and unsymmetric matrix, obtained from the O(h 7) method and the Newton-Raphson iteration method. Numerical results from the computer calculations are presented graphically. A comparison between this O(h 7) method and the shooting method, mainly from the viewpoint of computational efficiency, is also made.

  13. Microjoule sub-10 fs VUV pulse generation by MW pump pulses using highly efficient chirped four-wave mixing in hollow-core photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Im, Song-Jin

    2015-03-01

    We theoretically study chirped four-wave mixing for VUV pulse generation in hollow-core photonic crystal fibers. We predict the generation of sub-10 fs VUV pulses with energy of up to hundreds of µJ by broad-band chirped idler pulses at 830 nm and MW pump pulses with narrow-band at 277 nm. The MW pump could be desirable to reduce the complexity of the laser system or use a high repetition rate laser system. The energy conversion efficiency from pump pulse to VUV pulse reaches to 30% . This generation can be realized in a kagome-lattice hollow-core PCF filled with noble gas of high pressure with core diameter less than 40 µm, which would enable technically simple or highly efficient coupling to the fundamental mode of the fiber.

  14. Stable power multi-wavelength fibre laser based on four-wave mixing in a short length of highly non-linear fibre

    NASA Astrophysics Data System (ADS)

    Awang, N. A.; Zulkifli, M. Z.; Latif, A. A.; Harun, S. W.; Ahmad, H.

    2011-07-01

    A multi-wavelength fibre laser utilizing the four-wave mixing (FWM) effect in a 100 m long highly non-linear fibre (HNLF) is proposed and demonstrated. The multi-wavelength fibre laser is configured in a ring cavity and only needs a low power erbium doped fibre amplifier (EDFA) as the gain medium to generate 11 lines in the range of 1582-1600 nm with a signal-to-noise ratio (SNR) of 43 dB. The proposed system is very stable, with only minor fluctuations of 0.1 dB in the output power of the generated multi-wavelengths observed for a test period of more than an hour. The multi-wavelength fibre laser has many potential applications in optical communications and optical sensing systems.

  15. A proposal for enhancing four-wave mixing in slow light engineered photonic crystal waveguides and its application to optical regeneration.

    PubMed

    Ebnali-Heidari, M; Monat, C; Grillet, C; Moravvej-Farshi, M K

    2009-09-28

    In this paper, we investigate both analytically and numerically four-wave mixing (FWM) in short (80 microm) dispersion engineered slow light photonic crystal waveguides. We demonstrate that both a larger FWM conversion efficiency and an increased FWM bandwidth (approximately 10 nm) can be achieved in these waveguides as compared to dispersive PhC waveguides. This improvement is achieved through the net slow light enhancement of the FWM efficiency (almost 30dB as compared to a fast nanowire of similar length), even in the presence of slow light increased linear and nonlinear losses, and the suitable dispersion profile of these waveguides. We show how such improved FWM operation can be advantageously exploited for designing a compact 2R and 3R regenerator with the appropriate nonlinear power transfer function.

  16. Efficient high-power generation of visible and mid-infrared light by degenerate four-wave-mixing in a large-mode-area photonic-crystal fiber.

    PubMed

    Nodop, D; Jauregui, C; Schimpf, D; Limpert, J; Tünnermann, A

    2009-11-15

    An efficient and simple approach for converting pulsed near-IR laser radiation into visible and mid-IR light by exploiting degenerate four-wave-mixing in an endlessly single-mode, large-mode-area photonic-crystal fiber is presented. Coupling a 1 MHz, 200 ps, 8 W average power pulsed source emitting at 1064 nm into this fiber results in average powers of 3 W at 673 nm signal wavelength and of 450 mW at 2539 nm idler wavelength, respectively. The excellent pulse energy conversion efficiencies of 35% for the signal and 6% for the idler wavelength are due to the unique combination of characteristics of this type of fiber.

  17. χ{sup (3)} measurements of axial ligand modified high valent tin(IV) porphyrins using degenarete four wave mixing at 532nm

    SciTech Connect

    Narendran, N. K. Siji Chandrasekharan, K.; Soman, Rahul; Arunkumar, Chellaiah; Sudheesh, P.

    2014-10-15

    Porphyrins and metalloporphyrins are unique class of molecules for Nonlinear Optical applications because of their unique structure of altering the central metal atom, large extended π-system, high thermal stability, tunable shape, symmetry and synthetic versatility Here, we report χ{sup (3)} Measurements of a simple phenyl porphyrins and its highvalent tin(IV) porphyrins with Bromination characterized by UV-Visible spectroscopic method. In this study, we employed the Degenerate Four Wave Mixing technique using forward Boxcar geometry with an Nd:YAG nano second pulsed laser as source and it was found that the tin(IV) porphyrin with Bromination exhibits good χ{sup (3)} value and figure of merit.

  18. Measurements of exciton diffusion by degenerate four-wave mixing in CdS1-xSex

    NASA Astrophysics Data System (ADS)

    Schwab, H.; Pantke, K.-H.; Hvam, J. M.; Klingshirn, C.

    1992-09-01

    We performed transient-grating experiments to study the diffusion of excitons in CdS1-xSex mixed crystals. The decay of the initially created exciton density grating is well described for t<=1 ns by a stretched-exponential function. For later times this decay changes over to a behavior that is well fitted by a simple exponential function. During resonant excitation of the localized states, we find the diffusion coefficient (D) to be considerably smaller than in the binary compounds CdSe and CdS. At 4.2 K, D is below our experimental resolution which is about 0.025 cm2/s. With increasing lattice temperature (Tlattice) the diffusion coefficient increases. It was therefore possible to prove, in a diffusion experiment, that at Tlattice<=5 K the excitons are localized, while the exciton-phonon interaction leads to a delocalization and thus to the onset of diffusion. It was possible to deduce the diffusion coefficient of the extended excitons as well as the energetic position of the mobility edge.

  19. All-optical frequency downconversion technique utilizing a four-wave mixing effect in a single semiconductor optical amplifier for wavelength division multiplexing radio-over-fiber applications.

    PubMed

    Kim, Hyoung-Jun; Song, Jong-In

    2012-03-26

    An all-optical frequency downconversion utilizing a four-wave mixing effect in a single semiconductor optical amplifier (SOA) was experimentally demonstrated for wavelength division multiplexing (WDM) radio-over-fiber (RoF) applications. Two WDM optical radio frequency (RF) signals having 155 Mbps differential phase shift keying (DPSK) data at 28.5 GHz were simultaneously down-converted to two WDM optical intermediate frequency (IF) signals having an IF frequency of 4.5 GHz by mixing with an optical local oscillator (LO) signal having a LO frequency of 24 GHz in the SOA. The bit-error-rate (BER) performance of the RoF up-links with different optical fiber lengths employing all-optical frequency downconversion was investigated. The receiver sensitivity of the RoF up-link with a 6 km single mode fiber and an optical IF signal in an optical double-sideband format was approximately -8.5 dBm and the power penalty for simultaneous frequency downconversion was approximately 0.63 dB. The BER performance showed a strong dependence on the fiber length due to the fiber dispersion. The receiver sensitivity of the RoF up-link with the optical IF signal in the optical single-sideband format was reduced to approximately -17.4 dBm and showed negligible dependence on the fiber length.

  20. Near-resonant four-wave mixing of attosecond extreme-ultraviolet pulses with near-infrared pulses in neon: Detection of electronic coherences

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Warrick, Erika R.; Fidler, Ashley; Leone, Stephen R.; Neumark, Daniel M.

    2016-08-01

    Coherent narrow-band extreme-ultraviolet (EUV) light is generated by a near-resonant four-wave mixing (FWM) process between attosecond pulse trains and near-infrared pulses in neon gas. The near-resonant FWM process involves one vacuum-ultraviolet (VUV) photon and two near-infrared (NIR) photons and produces new higher-energy frequency components corresponding to the n s /n d to ground-state (2 s22 p6) transitions in the neon atom. The EUV emission exhibits small angular divergence (2 mrad) and monotonically increasing intensity over a pressure range of 0.5-16 Torr, suggesting phase matching in the production of the narrow-bandwidth coherent EUV light. In addition, time-resolved scans of the NIR nonlinear mixing process reveal the detection of a persistent, ultrafast bound electronic wave packet based on a coherent superposition initiated by the VUV pulse in the neon atoms. This FWM process using attosecond pulses offers a means for both efficient narrow-band EUV source generation and time-resolved investigations of ultrafast dynamics.

  1. Photoionization pathways and thresholds in generation of Lyman-α radiation by resonant four-wave mixing in Kr-Ar mixture

    NASA Astrophysics Data System (ADS)

    Louchev, Oleg A.; Saito, Norihito; Oishi, Yu; Miyazaki, Koji; Okamura, Kotaro; Nakamura, Jumpei; Iwasaki, Masahiko; Wada, Satoshi

    2016-09-01

    We develop a set of analytical approximations for the estimation of the combined effect of various photoionization processes involved in the resonant four-wave mixing generation of ns pulsed Lyman-α (L-α ) radiation by using 212.556 nm and 820-845 nm laser radiation pulses in Kr-Ar mixture: (i) multi-photon ionization, (ii) step-wise (2+1)-photon ionization via the resonant 2-photon excitation of Kr followed by 1-photon ionization and (iii) laser-induced avalanche ionization produced by generated free electrons. Developed expressions validated by order of magnitude estimations and available experimental data allow us to identify the area for the operation under high input laser intensities avoiding the onset of full-scale discharge, loss of efficiency and inhibition of generated L-α radiation. Calculations made reveal an opportunity for scaling up the output energy of the experimentally generated pulsed L-α radiation without significant enhancement of photoionization.

  2. Demonstration and optimisation of an ultrafast all-optical AND logic gate using four-wave mixing in a semiconductor optical amplifier

    SciTech Connect

    Razaghi, M; Nosratpour, A; Das, N K

    2013-02-28

    We have proposed an all-optical AND logic gate based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) integrated with an optical filter. In the scheme proposed, the preferred logical function can be performed without using a continuous-wave (cw) signal. The modified nonlinear Schroedinger equation (MNLSE) is used for the modelling wave propagation in a SOA. The MNLSE takes into account all nonlinear effects relevant to pico- and sub-picosecond pulse durations and is solved by the finite-difference beam-propagation method (FD-BPM). Based on the simulation results, the optimal output signal with a 40-fJ energy can be obtained at a bit rate of 50 Gb s{sup -1}. In the simulations, besides the nonlinearities included in the model, the pattern effect of the signals propagating in the SOA medium and the effect of the input signal bit rate are extensively investigated to optimise the system performance. (optical logic elements)

  3. Experimental generation of quadruple quantum-correlated beams from hot rubidium vapor by cascaded four-wave mixing using spatial multiplexing

    NASA Astrophysics Data System (ADS)

    Cao, Leiming; Qi, Jian; Du, Jinjian; Jing, Jietai

    2017-02-01

    Multimode quantum states, such as multipartite quantum entanglement or quantum correlations, are important for both fundamental science and the future development of quantum technologies. Here we theoretically propose and experimentally realize a scheme that can fully exploit the multi-spatial-mode nature of the four-wave-mixing (FWM) process, i.e., spatial multiplexing, and thus integrates multiple FWM processes into a single cell at each stage of the cascaded process. The number of generated quantum-correlated beams 2n is exponentially dependent on the number of vapor cells n . In addition, the quantum correlations between the multiple beams also increase as the number of vapor cell increases. For the case of n =2 , we experimentally show that the degree of intensity-difference squeezing between the four quantum-correlated beams in our scheme is enhanced to -8.2 ±0.2 dB from -5.6 ±0.3 and -6.5 ±0.2 dB of squeezing obtained with a single FWM process. Our system may find applications in quantum information and precision measurement.

  4. A C- and L-band dual-wavelength erbium-doped fibre laser for assisting four-wave mixing self-stability

    NASA Astrophysics Data System (ADS)

    Liu, Xueming; Zhao, Wei; Liu, Hongjun; Zou, Kuaisheng; Zhang, Tongyi; Lu, Keqing; Sun, Chuandong; Wang, Yishan; Ouyang, Xian; Chen, Guofu; Hou, Xun

    2006-06-01

    A kind of photonic 'Robin Hood' based on four-wave mixing is proposed and proved to be effective, theoretically and experimentally, in detail. Its applications for L-band dual-wavelength erbium-doped fibre (EDF) laser use are experimentally demonstrated at room temperature. The experimental results show that the conventional EDF cavity only induces a very unstable L-band laser, but the novel Robin Hood can effectively suppress the homogeneous gain in the erbium laser. By using suitable fibre Bragg gratings and stretching them, the proposed EDF laser can operate from ~1520 to ~1635 nm, so our dual-wavelength EDF laser can be used in lasing operation not only for the L band but also for the C band. The outstanding merits of our dual-wavelength laser are the flexible tuning and the ultrabroad spectral range of more than 115 nm. The experimental results show that the stability and uniformity of the proposed dual-wavelength laser in C-band operation are better than those for the same laser in L-band operation.

  5. APPLICATION OF LASERS AND LASER-OPTICAL METHODS IN LIFE SCIENCES Low-frequency four-wave mixing spectroscopy of biomolecules in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Bunkin, Aleksei F.; Pershin, S. M.

    2011-01-01

    Four-wave mixing (FWM) spectroscopy is used to detect the rotational resonances of H2O and H2O2 molecules in DNA and denatured DNA aqueous solutions in the range ±10 cm-1 with a spectral resolution of 3 GHz. It is found that the resonance contribution of the rotational transitions of these molecules increases significantly in solutions rather than in distilled water. This fact is interpreted as a manifestation of specific properties of a hydration layer at DNA—water and denatured DNA—water interfaces. Analysis of the FWM spectra shows that the concentration of H2O2 molecules in the hydration layer of the DNA solution increases by a factor of 3 after denaturation. The FWM spectra of aqueous solutions of α-chymotrypsin protein are obtained in the range ±7cm-1 at the protein concentrations between 0 and 20 mg cm-3. It is found that the hypersound velocity in the protein aqueous solution, measured by the shift of Brillouin components in the scattering spectrum, obeys a cubic dependence on the protein concentration and reaches a value of about 3000 m s-1 at 20 mg cm-3.

  6. Simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 using four-wave mixing spectroscopy.

    PubMed

    March, Samuel A; Clegg, Charlotte; Riley, Drew B; Webber, Daniel; Hill, Ian G; Hall, Kimberley C

    2016-12-15

    Solar cells incorporating organic-inorganic perovskite, which may be fabricated using low-cost solution-based processing, have witnessed a dramatic rise in efficiencies yet their fundamental photophysical properties are not well understood. The exciton binding energy, central to the charge collection process, has been the subject of considerable controversy due to subtleties in extracting it from conventional linear spectroscopy techniques due to strong broadening tied to disorder. Here we report the simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 films using four-wave mixing (FWM) spectroscopy. Due to the high sensitivity of FWM to excitons, tied to their longer coherence decay times than unbound electron- hole pairs, we show that the exciton resonance energies can be directly observed from the nonlinear optical spectra. Our results indicate low-temperature binding energies of 13 meV (29 meV) for the free (defect-bound) exciton, with the 16 meV localization energy for excitons attributed to binding to point defects. Our findings shed light on the wide range of binding energies (2-55 meV) reported in recent years.

  7. Synthesis, Z-Scan and Degenerate Four Wave Mixing characterization of certain novel thiocoumarin derivatives for third order nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Jayakrishnan, K.; Joseph, Antony; Mathew, K. Paulson; Siji, T. B.; Chandrasekharan, K.; Narendran, N. K. Siji; Jaseela, M. A.; Muraleedharan, K.

    2016-08-01

    The third order nonlinear optical features of certain novel thiocoumarin derivatives have been studied. Single beam Z-scan study on these compounds reveals that the compounds exhibit self defocusing effect upon irradiation with 532 nm, 7 ns pulses of Nd:YAG laser. Nonlinear absorption coefficient, nonlinear refractive index and second-order molecular hyperpolarizability values were estimated. The optical power limiting properties of the compounds are found to be attributable to both two-photon and excited state absorption. Some of the samples show nonlinear absorption coefficient (βeff) as high as 24.5 cm/GW. UV-Visible and photoluminescence outputs of these compounds reveal remarkable absorptive and emissive properties. This article also reports extraordinary growth of third order optical nonlinearity in pure coumarin upon certain donor substitutions in lieu of hydrogen. Degenerate Four Wave Mixing (DFWM) signals of the compounds were analyzed to verify the Z-scan results. Electrostatic Surface Potential (ESP) mapping and structure optimization techniques have been employed to interpret the structure-property relationship of each molecule.

  8. Wavelength conversion, time demultiplexing and multicasting based on cross-phase modulation and four-wave mixing in dispersion-flattened highly nonlinear photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Hui, Zhan-Qiang; Zhang, Jian-Guo

    2012-05-01

    We propose the use of cross-phase modulation (XPM) and four-wave mixing (FWM) in dispersion-flattened highly nonlinear photonic crystal fibers (HNL-PCFs) to implement the functionalities of wavelength conversion, simultaneous time demultiplexing and wavelength multicasting in optical time-division multiplexing (OTDM) systems. The experiments on wavelength conversion at 80 Gbit s-1and OTDM demultiplexing from 80 to 10 Gbit s-1 with wavelength multicasting of two channels are successfully demonstrated to validate the proposed scheme, which are carried out by using two segments of dispersion-flattened HNL-PCFs with lengths of 100 and 50 m, respectively. Moreover, the bit error rate (BER) performance is also measured. The results show that our designed system can achieve a power penalty of less than 4.6 dB for two multicasting channels with a 24 nm wavelength span at the BER of 10-9 when compared with the 10 Gbit/s back-to-back measurement. The proposed system is transparent to bit rate since only an ultrafast third-order nonlinear effect is used. The resulting configuration is compact, robust and reliable, benefiting from the use of dispersion-flattened HNL-PCFs with short lengths. This also makes the proposed system more flexible in the operational wavelengths than those based on dispersion-shifted fibers and traditional highly nonlinear fibers. The work was supported in part by the CAS/SAFEA International Partnership Program for Creative Research Teams.

  9. Influence of four-wave mixing in short- and medium-range 1310  nm dense wavelength division multiplexing systems.

    PubMed

    Markowski, Konrad; Chorchos, Łukasz; Turkiewicz, Jarosław Piotr

    2016-04-10

    In this paper, we demonstrate a comprehensive analysis of the impact of four-wave mixing (FWM) on the quality of transmission in short- and medium-range dense wavelength division multiplexing (DWDM) systems in the 1310 nm wavelength domain. The presented analysis proves that, for the system with uniform power per channel assignment, setting proper input channel power can substantially reduce the influence of the FWM effect on bit error rate in low channel spaced short-range systems, despite the position of the DWDM grid around the zero-dispersion wavelength. Simulations and experimental analysis of the possibility of FWM suppression have been provided. The power penalty measurements show that the influence of FWM on system performance may be as low as 0.3 dB with reasonable input power (i.e., -11  dBm per channel), making possible the transmission of data by fiber over distances of 25 km. Finally, we demonstrate that, for channel spacing as low as 120 GHz, error-free transmission in the 1310 nm wavelength domain is possible, despite high efficiency of FWM generation. The results prove that utilization of the 1310 nm wavelength domain in a system with low channel spacing, i.e., with better bandwidth allocation, is an interesting solution for data storage and processing center applications.

  10. Simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 using four-wave mixing spectroscopy

    PubMed Central

    March, Samuel A.; Clegg, Charlotte; Riley, Drew B.; Webber, Daniel; Hill, Ian G.; Hall, Kimberley C.

    2016-01-01

    Solar cells incorporating organic-inorganic perovskite, which may be fabricated using low-cost solution-based processing, have witnessed a dramatic rise in efficiencies yet their fundamental photophysical properties are not well understood. The exciton binding energy, central to the charge collection process, has been the subject of considerable controversy due to subtleties in extracting it from conventional linear spectroscopy techniques due to strong broadening tied to disorder. Here we report the simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 films using four-wave mixing (FWM) spectroscopy. Due to the high sensitivity of FWM to excitons, tied to their longer coherence decay times than unbound electron- hole pairs, we show that the exciton resonance energies can be directly observed from the nonlinear optical spectra. Our results indicate low-temperature binding energies of 13 meV (29 meV) for the free (defect-bound) exciton, with the 16 meV localization energy for excitons attributed to binding to point defects. Our findings shed light on the wide range of binding energies (2–55 meV) reported in recent years. PMID:27974815

  11. Deep-ultraviolet second-harmonic generation by combined degenerate four-wave mixing and surface nonlinearity polarization in photonic crystal fiber.

    PubMed

    Yuan, Jinhui; Kang, Zhe; Li, Feng; Zhou, Guiyao; Zhang, Xianting; Mei, Chao; Sang, Xinzhu; Wu, Qiang; Yan, Binbin; Zhou, Xian; Zhong, Kangping; Wang, Kuiru; Yu, Chongxiu; Lu, Chao; Tam, Hwa Yaw; Wai, P K A

    2017-08-23

    Deep-ultraviolet (UV) second-harmonics (SHs) have important applications in basic physics and applied sciences. However, it still remains challenging to generate deep-UV SHs especially in optical fibers. Here, for the first time, we experimentally demonstrate the deep-UV SH generations (SHGs) by combined degenerate four-wave mixing (FWM) and surface nonlinearity polarization in an in-house designed and fabricated air-silica photonic crystal fiber (PCF). When femtosecond pump pulses with average input power P av of 650 mW and center wavelength λ p of 810, 820, 830, and 840 nm are coupled into the normal dispersion region close to the zero-dispersion wavelength of the fundamental mode of the PCF, the anti-Stokes waves induced by degenerate FWM process are tunable from 669 to 612 nm. Then, they serve as the secondary pump, and deep-UV SHs are generated within the wavelength range of 334.5 to 306 nm as a result of surface nonlinearity polarization at the core-cladding interface of the PCF. The physical mechanism of the SHGs is confirmed by studying the dependences of the output power P SH of the SHs on the PCF length and time. Finally, we also establish a theoretical model to analyze the SHGs.

  12. Quasi-phase-matched four-wave mixing generation between C-band and mid-infrared regions using a symmetric hybrid plasmonic waveguide grating.

    PubMed

    Dai, Jing; Zhang, Minming; Zhou, Feiya; Wang, Yuanwu; Lu, Luluzi; Deng, Lei; Liu, Deming

    2015-08-10

    A symmetric hybrid plasmonic waveguide (SHPW) configuration based on quasi-phase-matched (QPM) four-wave mixing (FWM) is proposed to realize efficient FWM conversion between the C-band and mid-infrared (mid-IR) regions. Due to the ability to allow strong confinement of light, an extremely large nonlinear parameter γ>104  m-1 W-1 and a very low propagation loss ∼3×10-3  dB/μm accompanying the sub-λ scale (effective mode area Aeff∼3×10-2  μm2) are achieved by optimally designing the SHPW geometrical parameters. In addition, a QPM technique is adopted to achieve a relatively long effective length of FWM nonlinear process by constructing a long SHPW grating, thereby resulting in highly efficient wavelength conversion without rigorous dispersion engineering of waveguide structures. By using numerical simulations we have demonstrated that, for a pump wavelength of 1,800 nm, an efficient and flat FWM conversion of ∼-17  dB (∼-22  dB) could be realized around a target signal wavelength of the C-band: 1,530-1,565 nm (mid-IR: 2,118-2,180 nm), in a 1,000 μm-long grating with a serious phase mismatch.

  13. Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser assisted by multiple four-wave mixing processes in a ring cavity

    NASA Astrophysics Data System (ADS)

    Shirazi, M. R.; Mohamed Taib, J.; De La Rue, R. M.; Harun, S. W.; Ahmad, H.

    2015-03-01

    Dynamic characteristics of a multi-wavelength Brillouin-Raman fiber laser (MBRFL) assisted by four-wave mixing have been investigated through the development of Stokes and anti-Stokes lines under different combinations of Brillouin and Raman pump power levels and different Raman pumping schemes in a ring cavity. For a Stokes line of order higher than three, the threshold power was less than the saturation power of its last-order Stokes line. By increasing the Brillouin pump power, the nth order anti-Stokes and the (n+4)th order Stokes power levels were unexpectedly increased almost the same before the Stokes line threshold power. It was also found out that the SBS threshold reduction (SBSTR) depended linearly on the gain factor for the 1st and 2nd Stokes lines, as the first set. This relation for the 3rd and 4th Stokes lines as the second set, however, was almost linear with the same slope before SBSTR -6 dB, then, it approached to the linear relation in the first set when the gain factor was increased to 50 dB. Therefore, the threshold power levels of Stokes lines for a given Raman gain can be readily estimated only by knowing the threshold power levels in which there is no Raman amplification.

  14. All-optical four-wavelength 2R regeneration based on data-pump four-wave-mixing with offset filtering

    NASA Astrophysics Data System (ADS)

    Wen, Feng; Wu, Bao-Jian; Zhou, Xing-Yu; Yuan, Hao; Qiu, Kun

    2014-06-01

    A simultaneous all-optical 2R regeneration of 4 × 12.5 Gb/s return-to-zero (RZ) signals is demonstrated based on the data-pump four-wave-mixing in a single highly nonlinear fiber, in which the channel spacing and duty cycle are 200 GHz and 50%. Both the bidirectional configuration and time-interleaved technology are used to reduce the crosstalk from other channels. For further improving the performance of the multichannel regenerator, an offset filtering (OF) method is employed to minimize the influence from the opposite input signal. Our experiments show that the extinction ratio (ER) of regenerated signals is about two times larger than that of the degraded signals and the maximum ER improvement is about 6.5 dB. By using the offset filtering method, the sensitivity improvements of four-wavelength regenerated signals are 2.05 dB, 2.53 dB, 3.57 dB and 2.8 dB, respectively.

  15. [Characteristics of rubidium forward degenerate four-wave mixing (FDFWM) influenced by the matrix effect of chloride brine in graphite furnace].

    PubMed

    Wang, Jian; Ren, Zhao-Yu; Cheng, Xue-Mei; Miao, Yi-Zhu; Chen, Hao-Wei; Yin, Xun-Li; Wang, Li-Qin; Bai, Jin-Tao

    2012-06-01

    Rb is mainly extracted from brine. The authors studied the matrix effect of chloride brine (NaCl, CaCl2, KCl and MgCl2) on FDFWM (Forward phase-matching degenerate four-wave mixing) of Rb in the graphite furnace. The Rb and other chloride brine concentrations dependences of FDFWM were investigated respectively. The results indicate that with the increase in Rb concentration, FDFWM increases and reaches the highest at 80 ng x mL(-1). With the concentration of Rb sample further increasing, the FDFWM intensity drops. It was also found that when the Rb concentration is low, FDFWM signal is suppressed by the chloride brine, and the suppressing effect gets stronger with the increase in the chloride brine concentration. However, when the Rb concentration is high, FDFWM signal is first enhanced and then suppressed with the increase in the chloride brine concentration. The Cl- interference and Rb ionization in the graphite furnace were employed to explain the experimental results. This work is of important meaning in extracting and analyzing Rb in brine.

  16. Generation of visible wavelength by the phase-matching four-wave mixing in an Yb-doped V-shape photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Li, Lixiao; Yuan, Jinhui; Sang, Xinzhu; Yan, Binbin; Wang, Kuiru; Yu, Chongxiu; Han, Ying; Xia, Changming; Zhou, Guiyao; Wei, Shuai; Wang, Chao; Yang, Jianju; Wang, Shuang; Cheng, Xu; Hou, Lantian

    2015-07-01

    In this paper, an Ytterbium-doped V-shape photonic crystal fiber (Yb-VPCF) with low dispersion and high nonlinearity is designed and fabricated in our laboratory. Through coupling femtosecond pulses into the fundamental mode of Yb-VPCF, the tunable anti-Stokes signals at the visible wavelength are efficiently generated based on the phase-matching four-wave mixing. When the pump wavelength is changed from 810, to 820, and to 830 nm and the input average power is increased from 0.4, to 0.5, and to 0.6 W, respectively, the anti-Stokes signals are generated within the wavelength range of 562-477 nm. The wavelength-tunable range is over 100 nm, and the maximum power ratio of anti-Stokes signal at 477 nm and the residual pump at 830 nm can be up to 23.9:1. The anti-Stokes signals generated can be used as the ultrashort pulse sources for ultrafast optoelectronics and spectroscopy.

  17. Efficient and broadband Stokes wave generation by degenerate four-wave mixing at the mid-infrared wavelength in a silica photonic crystal fiber.

    PubMed

    Yuan, Jinhui; Sang, Xinzhu; Wu, Qiang; Zhou, Guiyao; Yu, Chongxiu; Wang, Kuiru; Yan, Binbin; Han, Ying; Farrell, Gerald; Hou, Lantian

    2013-12-15

    Based on degenerate four-wave mixing (FWM), the broadband Stokes waves are efficiently generated at the mid-infrared wavelength above 2 μm, for the first time to our knowledge, by coupling the femtosecond pulses into the fundamental mode of a silica photonic crystal fiber designed and fabricated in our laboratory. Influences of the power and wavelength of pump pulses on the phase-matched frequency conversion process are discussed. When pump pulses with central wavelength of 815 nm and average power of 300 mW are used, the output power ratio of the Stokes wave generated at 2226 nm and the residual pump wave P(s)/P(res) is estimated to be 10.8:1, and the corresponding conversion efficiency η(s) and bandwidth B(s) of the Stokes wave can be up to 26% and 33 nm, respectively. The efficient and broadband Stokes waves can be used as the ultrashort pulse sources for mid-infrared photonics and spectroscopy.

  18. Simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 using four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    March, Samuel A.; Clegg, Charlotte; Riley, Drew B.; Webber, Daniel; Hill, Ian G.; Hall, Kimberley C.

    2016-12-01

    Solar cells incorporating organic-inorganic perovskite, which may be fabricated using low-cost solution-based processing, have witnessed a dramatic rise in efficiencies yet their fundamental photophysical properties are not well understood. The exciton binding energy, central to the charge collection process, has been the subject of considerable controversy due to subtleties in extracting it from conventional linear spectroscopy techniques due to strong broadening tied to disorder. Here we report the simultaneous observation of free and defect-bound excitons in CH3NH3PbI3 films using four-wave mixing (FWM) spectroscopy. Due to the high sensitivity of FWM to excitons, tied to their longer coherence decay times than unbound electron- hole pairs, we show that the exciton resonance energies can be directly observed from the nonlinear optical spectra. Our results indicate low-temperature binding energies of 13 meV (29 meV) for the free (defect-bound) exciton, with the 16 meV localization energy for excitons attributed to binding to point defects. Our findings shed light on the wide range of binding energies (2–55 meV) reported in recent years.

  19. Nonlinear Optical Properties in Molecular Systems with Non-Zero Permanent Dipole Moments in Four-Wave Mixing Under Stochastic Considerations

    NASA Astrophysics Data System (ADS)

    Paz, J. L.; Mastrodomenico, A.; Cardenas-Garcia, Jaime F.; Rodriguez, Luis G.; Vera, Cesar Costa

    2016-07-01

    The solvent effects over nonlinear optical properties of a two-level molecular system in presence of a classical electromagnetic field were modeled in this work. The collective effects proper of the thermal reservoir are modeled as a random Bohr frequency, whose manifestation is the broadening of the upper level according to a prescribed random function. A technique of work, based in the use of the cumulant expansions to obtain the average in the Fourier components associated with the coherence and populations, evaluated by the use of the Optical Stochastic Bloch Equations (OSBE), is employed. Analytical expressions for susceptibility, optical properties and non-degenerate Four-Wave Mixing (nd-FWM) signal intensity, were obtained. Numerical calculations were carried out to construct surfaces corresponding to these magnitudes as a function of the pump-probe frequency detuning, values of the permanent dipole moments (PDM), noise parameters and relationships between the longitudinal and transversal relaxation times. Our results show that it is necessary to neglect the Rotating-Wave approximation (RWA) in order to measure the effect of the permanent dipole moments and that the inclusion of these favors two-photon transitions over those with one-photon. In general, the effect of non-zero permanent dipole moments, are reflected in the appearance of new and more complex signals associated with new multiphoton processes.

  20. Experimental observation of multi-spatial-mode quantum correlations in four-wave mixing with a conical pump and a conical probe

    NASA Astrophysics Data System (ADS)

    Du, Jinjian; Cao, Leiming; Zhang, Kai; Jing, Jietai

    2017-06-01

    Extensive attention has been drawn in generating multimode quantum states in recent years. Many efforts have been made during the last decade to produce such states. In this paper, we have experimentally demonstrated a scheme for generating a multi-spatial-mode quantum light source by a non-degenerated four-wave mixing process with a conical pump and a conical probe in a hot atomic vapor cell. The degree of the intensity-difference squeezing between the generated twin beams is about -4.1 dB. Due to the similar conical shape of the concentric quantum correlated beams, both the amplified probe and the generated conjugate beams can be decomposed into many angular modes. We have also experimentally verified the multi-spatial-mode nature of the generated quantum correlation by comparing the noise levels' variation tendencies of global attenuation and local cutting attenuations. In addition, we have also found the optimal values of each parameter in this scheme for further applications. Due to our scheme's advantages such as compactness, phase-insensitivity, and easy scalability, we have already shown a promising candidate for generating multi-spatial-mode quantum states, which may find potential applications in quantum metrology and quantum imaging, such as quantum-enhanced superresolution and the generation of multiple quantum correlated images.

  1. All-optical recognition method of double two-dimensional optical orthogonal codes-based labels using four-wave mixing

    NASA Astrophysics Data System (ADS)

    Zhang, Chongfu; Wang, Leyang; Perumal, Sathishkumar; Qiu, Kun; Zhou, Heng

    2011-08-01

    A novel all-optical label recognition method is proposed and demonstrated experimentally which is based on fiber Bragg gratings (FBGs)-based encoder/decoder and semiconductor optical amplifier (SOA). In this scheme, the optical label is firstly decoded properly, the decoded signal then generates the 1st and the 2nd order four-wave mixing (FWM) effect in different SOA, any of the frequencies achieved by the 2nd order FWM is extracted to recognize the optical label. The proposed solution can favor hardware simplicity over bandwidth efficiency in order to achieve the double two-dimensional optical orthogonal codes (2D-OOCs)-based optical label recognition in an optical packet switching (OPS) system where the bandwidth efficiency can be improved by FWM effect in SOA to achieve optical label processing and reasonable spacing of wavelengths for the payloads and optical label. The feasibility of the proposed method is validated by two experiments of the double 2D-OOCs-based optical label generation and recognition, the effect of the optical label on the payloads is also considered. These results show that the proposed method can (1) reduce effectively the code auto-correlation /cross-correlation requirements of the optical label identification and remove the cross-correlation pulses after optical decoding, (2) increase greatly the coding capacity and the number of the available optical labels, (3) improve the reliability and bandwidth efficiency of the optical label identification. The experimental results also show that the optical label has a high extinction ratio and can be operated easily.

  2. Characterization of the 1 ^5Πu - 1 ^5Πg Band of C_2 by Two-Color Resonant Four-Wave Mixing and Lif

    NASA Astrophysics Data System (ADS)

    Radi, Peter

    2015-06-01

    The application of two-color resonant four-wave mixing (TC-RFWM) in combination with a discharge slit-source in a molecular beam environment is advantageous for the study of perturbations in C_2. Initial investigations have shown the potential of the method by a detailed deperturbation of the d3Π_g, v=4 state. The deperturbation of the d3Π_g, v=6 state unveiled the presence of the energetically lowest high-spin state of C_2. This dark state gains transition strength through the perturbation process with the d3Π_g, v=6 state yielding weak spectral features that are observable by the high sensitivity of the TC-RFWM technique. The successful deperturbation study of the d3Π_g, v=6 state resulted in the spectroscopic characterization of the quintet (15Πg) and an additional triplet state (d3Π_g, v=19). More recently, investigations have been performed by applying unfolded TC-RFWM to obtain further information on the quintet manifold. The first high-spin transition (15Πu) - 15Πg)) has been observed via an intermediate ``gateway'' state exhibiting both substantial triplet and quintet character owing to the perturbation between the 15Πg), v=0 and the d3Π_g, v=6 states. The high-lying quintet state is found to be predissociative and displays a shallow potential that accommodates three vibrational levels only. Further studies of the high-spin system will be presented in this contribution. By applying TC-RFWM and laser-induced fluorescence, data on the vibrational structure of the 15Πu - 15Πg system is obtained. The results are combined with high-level ab initio computations at the multi-reference configuration interaction (MRCI) level of theory and the largest possible basis currently implemented in the 2012 version of MOLPRO. P. Bornhauser, G. Knopp, T. Gerber, and P.P. Radi, Journal of Molecular Spectroscopy 262, 69 (2010) P. Bornhauser, Y. Sych, G. Knopp, T. Gerber, and P.P. Radi, Journal of Chemical Physics 134, 044302 (2011) Bornhauser, P., Marquardt, R

  3. Noise characterization in double-heralded generation of two-photon-states by spontaneous four-wave-mixing

    NASA Astrophysics Data System (ADS)

    Smith, Roger A.; Reddy, Dileep V.; Vitullo, Dashiell L. P.; Raymer, Michael G.

    2016-09-01

    In quantum optics experiments, heralding, a form of conditional state preparation, is a useful tool for creating photon-number states from nonlinear optical sources for quantum-information science experiments. Heralding occurs when one photon from a correlated pair is detected to herald the presence of the other photon, labeled the signal photon. However, as heralding is extended to two or more photon pairs, the presence of noise photons in the herald channel quickly degrades the photon statistics of the signal photons. We create two-photon number states from a non-degenerate, third-order nonlinear optical fiber source with double heralding and present a method for verifying these photon-number states. The consequences of noisy heralding on the statistics of states created via third-order nonlinear processes are analyzed. We present a method for estimating the effects of noise photons on the signal photon statistics. Additionally, we prove the equivalence between noise in the herald channel and a loss in the signal channel. We utilize this equivalence to infer the photon statistics of the photon-number states in the signal channel that would be present in the absence of noise in the herald channel. By measuring the statistics of the signal channels with noise in the herald channel and comparing to the inferred, noise-free distribution, we can estimate the potential benefits of additional noise-reducing procedures on the experiment.

  4. Spontaneous four-wave mixing in liquid-core fibers: towards fibered Raman-free correlated photon sources

    NASA Astrophysics Data System (ADS)

    Barbier, M.; Zaquine, I.; Delaye, P.

    2015-05-01

    We experimentally demonstrate, for the first time to our knowledge, the generation of correlated photon pairs in a liquid-core photonic crystal fiber. Moreover, we show that, thanks to the specific Raman properties of liquids, the Raman noise (which is the main limitation of the performance of silica-core fiber-based correlated photon pair sources) is highly reduced. With a demonstrated coincident-to-accidental ratio equal to 63 and a pair generation efficiency of about 10-4 per pump pulse, this work contributes to the development of high-quality correlated photon pair sources for quantum communications.

  5. Tunable error-free optical frequency conversion of a 4ps optical short pulse over 25 nm by four-wave mixing in a polarisation-maintaining optical fibre

    NASA Astrophysics Data System (ADS)

    Morioka, T.; Kawanishi, S.; Saruwatari, M.

    1994-05-01

    Error-free, tunable optical frequency conversion of a transform-limited 4.0 ps optical pulse signalis demonstrated at 6.3 Gbit/s using four-wave mixing in a polarization-maintaining optical fibre. The process generates 4.0-4.6 ps pulses over a 25nm range with time-bandwidth products of 0.31-0.43 and conversion power penalties of less than 1.5 dB.

  6. Generation of 3.6  μm radiation and telecom-band amplification by four-wave mixing in a silicon waveguide with normal group velocity dispersion.

    PubMed

    Kuyken, B; Verheyen, P; Tannouri, P; Liu, X; Van Campenhout, J; Baets, R; Green, W M J; Roelkens, G

    2014-03-15

    Mid-infrared light generation through four-wave mixing-based frequency down-conversion in a normal group velocity dispersion silicon waveguide is demonstrated. A telecom-wavelength signal is down-converted across more than 1.2 octaves using a pump at 2190 nm in a 1 cm-long waveguide. At the same time, a 13 dB on-chip parametric gain of the telecom signal is obtained.

  7. Measurements of the nonlinear refractive index of air, N2, and O2 at 10 μm using four-wave mixing.

    PubMed

    Pigeon, J J; Tochitsky, S Ya; Welch, E C; Joshi, C

    2016-09-01

    We report on measurements of the nonlinear index of refraction of air, N2, and O2 at a wavelength close to 10 μm by collinear four-wave mixing of a 200 MW CO2 laser beat-wave. The use of a 200 ps long beat-wave comprising radiation amplified on the 10P20 and 10R16 lines of the CO2 laser provides a sensitive method to measure the small nonlinearities characteristic of the gas phase in a spectral region where no such data exists.

  8. Determining the nature of excitonic dephasing in high-quality GaN/AlGaN quantum wells through time-resolved and spectrally resolved four-wave mixing spectroscopy

    NASA Astrophysics Data System (ADS)

    Gallart, M.; Ziegler, M.; Crégut, O.; Feltin, E.; Carlin, J.-F.; Butté, R.; Grandjean, N.; Hönerlage, B.; Gilliot, P.

    2017-07-01

    Applying four-wave mixing spectroscopy to a high-quality GaN/AlGaN single quantum well, we report on the experimental determination of excitonic dephasing times at different temperatures and exciton densities in III-nitride heterostructures. By comparing the evolution with the temperature of the dephasing and the spin-relaxation rate, we conclude that both processes are related to the rate of excitonic collisions. When spin relaxation occurs in the motional-narrowing regime, it remains constant over a large temperature range as the spin-precession frequency increases linearly with temperature, hence compensating for the observed decrease in the dephasing time. From those measurements, a value of the electron-hole exchange interaction strength of 0.45 meV at T =10 K is inferred.

  9. Mass-analyzed threshold ionization study of vinyl bromide cation in the first excited electronic state using vacuum-ultraviolet radiation generated by four-wave mixing in Hg

    NASA Astrophysics Data System (ADS)

    Lee, Mina; Kim, Myung Soo

    2005-11-01

    The vibrational spectrum of the vinyl bromide cation in the first excited electronic state ÃA'2 was obtained by one-photon mass-analyzed threshold ionization (MATI) spectroscopy. The use of an improved vacuum-ultraviolet radiation source based on four-wave sum frequency mixing in Hg resulted in excellent sensitivity for MATI signals. From the MATI spectrum, the ionization energy to the ÃA'2 state of the cation was determined to be 10.9150±0.0006eV. Nearly complete vibrational assignments for the MATI peaks were possible by utilizing the vibrational frequencies and Franck-Condon factors calculated at the density-functional theory (DFT) and time-dependent DFT/B3LYP levels with the 6-311+G(df,p) basis set.

  10. Phase-matched four-wave mixing of sub-100-TW/ cm2 femtosecond laser pulses in isolated air-guided modes of a hollow photonic-crystal fiber.

    PubMed

    Konorov, S O; Serebryannikov, E E; Akimov, D A; Ivanov, A A; Alfimov, M V; Zheltikov, A M

    2004-12-01

    Hollow-core photonic-crystal fibers are shown to allow propagation and nonlinear-optical frequency conversion of high-intensity ultrashort laser pulses in the regime of isolated guided modes confined in the hollow gas-filled fiber core. With a specially designed dispersion of such modes, the 3omega=2omega+2omega-omega four-wave mixing of fundamental (omega) and second-harmonic (2omega) sub-100- TW/ cm(2) femtosecond pulses of a Cr:forsterite laser can be phase matched in a hollow photonic-crystal fiber within a spectral band of more than 10 nm, resulting in the efficient generation of femtosecond pulses in a well-resolved higher-order air-guided mode of 417-nm radiation.

  11. Highly efficient non-degenerate four-wave mixing under dual-mode injection in InP/InAs quantum-dash and quantum-dot lasers at 1.55 μm

    SciTech Connect

    Sadeev, T. Arsenijević, D.; Huang, H.; Schires, K.; Grillot, F.; Bimberg, D.

    2015-11-09

    This work reports on non-degenerate four-wave mixing under dual-mode injection in metalorganic vapor phase epitaxy grown InP/InAs quantum-dash and quantum dot Fabry-Perot laser operating at 1550 nm. High values of normalized conversion efficiency of −18.6 dB, optical signal-to-noise ratio of 37 dB, and third order optical susceptibility normalized to material gain χ{sup (3)}/g{sub 0} of ∼4 × 10{sup −19} m{sup 3}/V{sup 3} are measured for 1490 μm long quantum-dash lasers. These values are similar to those obtained with distributed-feedback lasers and semiconductor optical amplifiers, which are much more complicated to fabricate. On the other hand, due to the faster gain saturation and enhanced modulation of carrier populations, quantum-dot lasers demonstrate 12 dB lower conversion efficiency and 4 times lower χ{sup (3)}/g{sub 0} compared to quantum dash lasers.

  12. Design of optical time-division multiplexed systems using the cascaded four-wave mixing in a highly nonlinear photonic crystal fiber for simultaneous time demultiplexing and wavelength multicasting

    NASA Astrophysics Data System (ADS)

    Hui, Zhan-Qiang; Zhang, Jian-Guo

    2015-07-01

    This paper reports a new design of optical time-division multiplexed (OTDM) systems that possess a functionality of simultaneous time demultiplexing and wavelength multicasting based on the cascaded four-wave mixing in a dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF). A module of OTDM demultiplexing and wavelength multicasting can be feasibly implemented by using a 3 dB optical coupler, a high-power erbium-doped fiber amplifier, a short-length DF-HNL-PCF, and a wavelength demultiplexer in the simple configuration. We also carry out an experiment on the proposed system to demonstrate the 100-10 Gbit s-1 OTDM demultiplexing with wavelength conversion simultaneously at 4 multicast wavelengths. It is shown that error-free wavelength multicasting is achieved on two wavelength channels with the minimum power penalty of 3.2 dB relative to the 10 Gbit s-1 back-to-back measurement, whereas the bit error rates of other two multicasting channels are measured to be about 10-6-10-5. Moreover, we propose the use of a proper error-correcting code to improve the multicasting performance of such an OTDM system, and our work reveals that the resulting system can theoretically support error-free multicasting of the OTDM-demultiplexed signal on four wavelength channels.

  13. All-optical NRZ-to-RZ format conversion at 10 Gbit/s with 1-to-4 wavelength multicasting exploiting cross-phase modulation & four-wave-mixing in single dispersion-flattened highly nonlinear photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Hui, Zhan-Qiang; Zhang, Bo; Zhang, Jian-Guo

    2016-04-01

    All-optical NRZ-to-RZ format conversion with a function of wavelength multicasting is proposed in this paper, which is realized by exploiting cross-phase modulation (XPM) and four-wave-mixing (FWM) in a dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF). The designed format converter is experimentally demonstrated, for which the 1-to-4 wavelength multicasting is achieved simultaneously by filtering out two FWM idler waves and both blue-chirped and red-chirped components of the broadened NRZ spectrum induced by XPM. Moreover, the wavelength tunability and dynamic characteristics of the proposed NRZ-to-RZ format converter are also exploited using the different central wavelengths of an optical clock signal and varying the input optical power at a DF-HNL-PCF in our experiment. It is shown that the designed format converter can possess a wide range of operational wavelength over 17 nm, an optimal extinction ratio of 11.6 dB, and a Q-factor of 7.1, respectively. Since the proposed scheme uses an optical fiber-based configuration and is easy for implementation, it can be very useful for future applications in advanced fiber-optic communication networks.

  14. Electrically controllable spontaneous magnetism in nanoscale mixed phase multiferroics.

    PubMed

    He, Q; Chu, Y-H; Heron, J T; Yang, S Y; Liang, W I; Kuo, C Y; Lin, H J; Yu, P; Liang, C W; Zeches, R J; Kuo, W C; Juang, J Y; Chen, C T; Arenholz, E; Scholl, A; Ramesh, R

    2011-01-01

    Magnetoelectrics and multiferroics present exciting opportunities for electric-field control of magnetism. However, there are few room-temperature ferromagnetic-ferroelectrics. Among the various types of multiferroics the bismuth ferrite system has received much attention primarily because both the ferroelectric and the antiferromagnetic orders are quite robust at room temperature. Here we demonstrate the emergence of an enhanced spontaneous magnetization in a strain-driven rhombohedral and super-tetragonal mixed phase of BiFeO₃. Using X-ray magnetic circular dichroism-based photoemission electron microscopy coupled with macroscopic magnetic measurements, we find that the spontaneous magnetization of the rhombohedral phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent tetragonal-like phase and the epitaxial constraint. Reversible electric-field control and manipulation of this magnetic moment at room temperature is also shown.

  15. Electrically Controllable Spontaneous Magnetism in Nanoscale Mixed Phase Multiferroics

    SciTech Connect

    He, Q.; Chu, Y. H.; Heron, J. T.; Yang, S. Y.; Wang, C. H.; Kuo, C. Y.; Lin, H. J.; Yu, P.; Liang, C. W.; Zeches, R. J.; Chen, C. T.; Arenholz, E.; Scholl, A.; Ramesh, R.

    2010-08-02

    The emergence of enhanced spontaneous magnetic moments in self-assembled, epitaxial nanostructures of tetragonal (T-phase) and rhombohedral phases (R-phase) of the multiferroic BiFeO{sub 3} system is demonstrated. X-ray magnetic circular dichroism based photoemission electron microscopy (PEEM) was applied to investigate the local nature of this magnetism. We find that the spontaneous magnetization of the R-phase is significantly enhanced above the canted antiferromagnetic moment in the bulk phase, as a consequence of a piezomagnetic coupling to the adjacent T-phase and the epitaxial constraint. Reversible electric field control and manipulation of this magnetic moment at room temperature is shown using a combination of piezoresponse force microscopy and PEEM studies.

  16. Nonlinear Optics Technology, Area 1: FWM (Four Wave Mixing) Technology

    DTIC Science & Technology

    1986-09-22

    41 0 u Q)Co o 0 0. >1- o 0 41 -A $4 P4 38 paths to insure a high degree of copolarization at the Na cell. Turning mirrors (M) were visible dielectric...or MAXBRIte coated Zerodur substrate optics with twentieth wave or better surface figures. A 50-50 beamsplitter (BSl) served to generate the two pump...retroreflecting mirror . The signal beam, which essentially constituted a very bright glint, was split off of the pump leg by a beamsplitter and directed to a

  17. Optical gyroscope with controllable dispersion in four wave mixing regime.

    NASA Astrophysics Data System (ADS)

    Mikhailov, Eugeniy; Wolfe, Owen; Du, Shuangli; Rochester, Simon; Budker, Dmitry; Novikova, Irina

    2016-05-01

    We present our work towards realization of the fast-light gyroscope prototype, in which the sensitivity enhancement (compared to a regular laser gyroscopes) is achieved by adjusting the intra-cavity dispersion. We discuss schematics and underlying nonlinear effects leading to the negative dispersion in Rb vapor: level structure, optically addressed transitions, and configuration of the resonant cavity. We investigate dependence of the pulling factor (i.e., the ratio of the lasing frequency shift with the change of the cavity length to the equivalent resonance frequency shift in the empty cavity) on pump lasers detunings, power, and density of the atomic vapor. The observation of the pulling factor exceeding unity implies the gyroscope sensitivity improvement over the regular system This work is supported by Naval Air Warfare Center STTR program N68335-11-C-0428.

  18. Mixed lipid bilayers with locally varying spontaneous curvature and bending.

    PubMed

    Gueguen, Guillaume; Destainville, Nicolas; Manghi, Manoel

    2014-08-01

    A model of lipid bilayers made of a mixture of two lipids with different average compositions on both leaflets, is developed. A Landau Hamiltonian describing the lipid-lipid interactions on each leaflet, with two lipidic fields ψ 1 and ψ 2, is coupled to a Helfrich one, accounting for the membrane elasticity, via both a local spontaneous curvature, which varies as C 0 + C 1(ψ 1 - ψ 2/2), and a bending modulus equal to κ 0 + κ 1(ψ 1 + ψ 2)/2. This model allows us to define curved patches as membrane domains where the asymmetry in composition, ψ 1 - ψ 2, is large, and thick and stiff patches where ψ 1 + ψ 2 is large. These thick patches are good candidates for being lipidic rafts, as observed in cell membranes, which are composed primarily of saturated lipids forming a liquid-ordered domain and are known to be thick and flat nano-domains. The lipid-lipid structure factors and correlation functions are computed for globally spherical membranes and planar ones and for a whole set of parameters including the surface tension and the coupling in the two leaflet compositions. Phase diagrams are established, within a Gaussian approximation, showing the occurrence of two types of Structure Disordered phases, with correlations between either curved or thick patches, and an Ordered phase, corresponding to the divergence of the structure factor at a finite wave vector. The varying bending modulus plays a central role for curved membranes, where the driving force κ 1 C 0 (2) is balanced by the line tension, to form raft domains of size ranging from 10 to 100 nm. For planar membranes, raft domains emerge via the cross-correlation with curved domains. A global picture emerges from curvature-induced mechanisms, described in the literature for planar membranes, to coupled curvature- and bending-induced mechanisms in curved membranes forming a closed vesicle.

  19. Spontaneous Esophageal Perforation in a Patient with Mixed Connective Tissue Disease

    PubMed Central

    Lyman, David

    2011-01-01

    Spontaneous esophageal perforation is a rare and life-threatening disorder. Failure to diagnosis within the first 24-48 hours of presentation portends a poor prognosis. A patient with mixed connective tissue disease (MCTD) on low-dose prednisone and methotrexate presented moribund with chest and shoulder pain, a left hydropneumothorax, progressive respiratory failure and shock. Initial management focussed on presumed community acquired pneumonia (CAP) in a patient on immunosuppressants. Bilateral yeast empyemas were treated and attributed to immunosuppression. On day 26, the patient developed mediastinitis, and the diagnosis of esophageal perforation was first considered. A review of the literature suggests that the diagnosis and management of spontaneous esophageal perforation could have been more timely and the outcome less catastrophic. PMID:22279514

  20. A new model of central lid margin apposition and tear film mixing in spontaneous blinking.

    PubMed

    Pult, Heiko; Korb, Donald R; Murphy, Paul J; Riede-Pult, Britta H; Blackie, Caroline

    2015-06-01

    To investigate tear film spreading and central lid position in spontaneous blinks and to propose a model of the central lid position of the closed eye in such blinks. In vivo: lid margin position and geometry of 15 subjects (9 female; median age=45 years) were evaluated by high-speed video and slit-lamp microscope video in consecutive spontaneous blinks. Upper lid (UL) tear meniscus (TM) depth was observed in the open and almost closed eye. Eyelid geometry, position and UL TM depth were analysed by Image-J Software. Lid margin thicknesses were measured with a Scheimpflug camera. In vitro: tear film spreading and lipid layer formation were simulated on a lubricated glass plate and videoed by high-speed camera (JVC, GZ-GX1BE, Japan). In vivo: the median central lid margin thickness was not significantly (p=0.258) different between UL (1.8mm) and LL (1.7mm) in the opened eye. During blinking, UL remained perpendicular to the corneal surface, while LL tilted in and thinned. A scaled model diagram was created and revealed an over-blink of the UL over the LL (>0.7mm) and a height offset of the posterior lid margin of >0.7mm. In vitro: the LL TM fused with the UL TM even before full lid touch due to capillary bridge building. The central UL overlaps the central LL during spontaneous blinking. This provides the appearance of complete closure. The space that results from the lack of lid margin apposition influences the fusion of the upper and lower TM and ultimately tear film mixing. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  1. Wave-turbulence theory of four-wave nonlinear interactions

    NASA Astrophysics Data System (ADS)

    Chibbaro, Sergio; Dematteis, Giovanni; Josserand, Christophe; Rondoni, Lamberto

    2017-08-01

    The Sagdeev-Zaslavski (SZ) equation for wave turbulence is analytically derived, both in terms of a generating function and of a multipoint probability density function (PDF), for weakly interacting waves with initial random phases. When the initial amplitudes are also random, a one-point PDF equation is derived. Such analytical calculations remarkably agree with results obtained in totally different fashions. Numerical investigations of the two-dimensional nonlinear Schrödinger equation (NLSE) and of a vibrating plate prove the following: (i) Generic Hamiltonian four-wave systems rapidly attain a random distribution of phases independently of the slower dynamics of the amplitudes, vindicating the hypothesis of initially random phases. (ii) Relaxation of the Fourier amplitudes to the predicted stationary distribution (exponential) happens on a faster time scale than relaxation of the spectrum (Rayleigh-Jeans distribution). (iii) The PDF equation correctly describes dynamics under different forcings: The NLSE has an exponential PDF corresponding to a quasi-Gaussian solution, as the vibrating plates, that also shows some intermittency at very strong forcings.

  2. Establishment of primary mixed cell cultures from spontaneous canine mammary tumors: Characterization of classic and new cancer-associated molecules

    PubMed Central

    Gentile, Luciana B.; Nagamine, Marcia K.; Biondi, Luiz R.; Sanches, Daniel S.; Toyota, Fábio; Giovani, Tatiane M.; de Jesus, Isis P.; da Fonseca, Ivone I. M.; Queiroz-Hazarbassanov, Nicolle; Diaz, Bruno L.; Salles Gomes, Cristina de O. Massoco

    2017-01-01

    There are many factors which make canine cancer like cancer in humans. The occurrence of spontaneous mammary tumors in pet dogs, tumor genetics, molecular targets and exposure to the same environmental risk factors are among these factors. Therefore, the study of canine cancer can provide useful information to the oncology field. This study aimed to establish and characterize a panel of primary mixed cell cultures obtained from spontaneous canine mammary tumors. Eight established cell cultures obtained from one normal mammary gland, one complex adenoma, one mixed adenoma, two complex carcinomas and two mixed carcinomas were analyzed. The gene expression levels of classic molecular cancer players such as fibroblast growth factor receptor (FGFR) 2, breast cancer (BRCA) 1, BRCA2 and estrogen receptor (ESR) 1 were evaluated. For the first time, three orphan nuclear receptors, estrogen-related receptors (ERRs) α, β and γ were studied in canine mammary cancer. The highest expression level of ERRα was observed in complex carcinoma-derived cell culture, while the highest levels of ERRβ and γ were observed in cells derived from a mixed carcinoma. Meanwhile, complex carcinomas presented the highest levels of expression of ESR1, BRCA1 and FGFR2 among all samples. BRCA2 was found exclusively in complex adenoma. The transcription factor GATA3 had its highest levels in mixed carcinoma samples and its lowest levels in complex adenoma. Proliferation assays were also performed to evaluate the mixed cell cultures response to ER ligands, genistein and DES, both in normoxia and hypoxic conditions. Our results demonstrate that morphological and functional studies of primary mixed cell cultures derived from spontaneous canine mammary tumors are possible and provide valuable tool for the study of various stages of mammary cancer development. PMID:28945747

  3. Establishment of primary mixed cell cultures from spontaneous canine mammary tumors: Characterization of classic and new cancer-associated molecules.

    PubMed

    Gentile, Luciana B; Nagamine, Marcia K; Biondi, Luiz R; Sanches, Daniel S; Toyota, Fábio; Giovani, Tatiane M; de Jesus, Isis P; da Fonseca, Ivone I M; Queiroz-Hazarbassanov, Nicolle; Diaz, Bruno L; Salles Gomes, Cristina de O Massoco; Dagli, Maria Lucia Z

    2017-01-01

    There are many factors which make canine cancer like cancer in humans. The occurrence of spontaneous mammary tumors in pet dogs, tumor genetics, molecular targets and exposure to the same environmental risk factors are among these factors. Therefore, the study of canine cancer can provide useful information to the oncology field. This study aimed to establish and characterize a panel of primary mixed cell cultures obtained from spontaneous canine mammary tumors. Eight established cell cultures obtained from one normal mammary gland, one complex adenoma, one mixed adenoma, two complex carcinomas and two mixed carcinomas were analyzed. The gene expression levels of classic molecular cancer players such as fibroblast growth factor receptor (FGFR) 2, breast cancer (BRCA) 1, BRCA2 and estrogen receptor (ESR) 1 were evaluated. For the first time, three orphan nuclear receptors, estrogen-related receptors (ERRs) α, β and γ were studied in canine mammary cancer. The highest expression level of ERRα was observed in complex carcinoma-derived cell culture, while the highest levels of ERRβ and γ were observed in cells derived from a mixed carcinoma. Meanwhile, complex carcinomas presented the highest levels of expression of ESR1, BRCA1 and FGFR2 among all samples. BRCA2 was found exclusively in complex adenoma. The transcription factor GATA3 had its highest levels in mixed carcinoma samples and its lowest levels in complex adenoma. Proliferation assays were also performed to evaluate the mixed cell cultures response to ER ligands, genistein and DES, both in normoxia and hypoxic conditions. Our results demonstrate that morphological and functional studies of primary mixed cell cultures derived from spontaneous canine mammary tumors are possible and provide valuable tool for the study of various stages of mammary cancer development.

  4. Counting neutrons from the spontaneous fission of {sup 238}U using scintillation detectors and mixed field analysers

    SciTech Connect

    Parker, Helen M. O'D.; Joyce, Malcolm J.; Jones, Ashley

    2015-07-01

    It is well documented that {sup 238}U decays by spontaneous fission, and that it is the main component of most nuclear fuels. As nuclear fuels are largely classed as Special Nuclear Material (SNM), they have to be fully accounted for by owners and processing facilities. One possible method for verifying declared amounts of SNM is to count the spontaneous neutrons produced from {sup 238}U. Using four EJ-309 liquid scintillation detectors and a mixed field analyser, spontaneous neutrons from 16.4 g of depleted uranium (0.3% enrichment) have been assayed. The assay method shows promising results and this proof of principle will be researched further in order for it to be applied in an industrial setting. (authors)

  5. Mixed cryoglobulinemia-associated Sjögren’s syndrome leading to spontaneous rupture of the kidney: a case report

    PubMed Central

    Haddiya, Intissar; Hamzaoui, Hakim; Alhamany, Zitouna; Berkchi, Fatime-zohra; Rhou, Hakima; Benamar, Loubna; Ouzeddoun, Naima; Bayahia, Rabea

    2016-01-01

    Background Spontaneous rupture of the kidney is uncommon and is mainly caused by renal tumors. Only a few cases are caused by vasculitis. We report here the first case of spontaneous rupture of kidney resulting from mixed cryoglobulinemia. Case presentation A 44-year-old man presented with sudden onset of fever, acute pulmonary edema, left flank abdominal pain unassociated with trauma, and rapidly progressive renal failure requiring dialysis. Computed tomography of the abdomen revealed a large perirenal hematoma of the left kidney. During conservative surgery, the patient underwent renal biopsy that showed renal vasculitis and membranoproliferative glomerulonephritis with intracapillary microthrombi. Tests were positive for mixed cryoglobulinemia caused by Sjögren’s syndrome. The patient was better after immunosuppressive therapy, with the disappearance of clinical symptoms and the recovery of baseline renal function. Conclusion We report on this case and discuss a possible link between spontaneous rupture of kidney and mixed cryoglobulinemia-associated Sjögren’s syndrome. PMID:27042145

  6. Comparative analysis of the use of various solid-state laser media for the self-starting of four-wave PCW generation in a loop laser resonator

    NASA Astrophysics Data System (ADS)

    Smetanin, Sergei N.

    2013-01-01

    A generalised theory has been used to carry out a comparative analysis of the use of various four-level and quasi-threelevel media for the self-starting of degenerate four-wave mixing PCW generation directly in a laser medium placed in a loop resonator. It has been shown that quasi-three-level media can compete with four-level media at long upper laser level lifetimes and increased pump intensities. The most attractive solid-state laser media for four-wave PCW generation have been identified that have the highest deposited energy at a given pump intensity. In addition to neodymium-doped crystals, which are already widely used for four-wave PCW generation, promising materials are fourlevel chromium-doped media, e.g. alexandrite and Cr : LiCAF, and quasi-three-level media with the longest upper laser level lifetime, such as Yb : YAG and Tm, Ho : YAG, at high pump intensities.

  7. Four-wave parametric amplification in semiconductor quantum dot-metallic nanoparticle hybrid molecules.

    PubMed

    Li, Jian-Bo; He, Meng-Dong; Chen, Li-Qun

    2014-10-06

    We study theoretically four-wave parametric amplification arising from the nonlinear optical response of hybrid molecules composed of semiconductor quantum dots and metallic nanoparticles. It is shown that highly efficient four-wave parametric amplification can be achieved by adjusting the frequency and intensity of the pump field and the distance between the quantum dot and the metallic nanoparticle. Specifically, the induced probe-wave gain is tunable in a large range from 1 to 1.43 × 10⁵. This gain reaches its maximum at the position of three-photon resonance. Our findings hold great promise for developing four-wave parametric oscillators.

  8. Degenerate four-wave mixing in a mercury-argon discharge

    NASA Technical Reports Server (NTRS)

    Richardson, W.; Maleki, L.; Garmire, E.

    1986-01-01

    Phase conjugation has been obtained with pump powers as low as 0.5 mW on the 546.1-nm line of atomic mercury. Collisional processes that oppose the effects of optical pumping sustain the signal. Line splittings observed in the Doppler regime are compared with theory. Reflectivities agree with those obtained from a model that includes pump absorption.

  9. Experimental method for the determination of two-photon cross sections using four-wave mixing

    NASA Technical Reports Server (NTRS)

    Burris, J.; Mcilrath, T. J.

    1985-01-01

    The two-photon absorption cross section for the R22 + S12(J double prime = 9 1/2) transition in nitric oxide's gamma band has been determined. The value is in good agreement with previous measurements on several other NO transitions. The technique described here can be used to obtain accurate cross sections for other diatomic molecules.

  10. Four-Wave Mixing And Scanning Tunneling Microscopy Of Semiconductor Clusters

    NASA Astrophysics Data System (ADS)

    Sarid, Dror; McGinnis, B. P.; Henson, Tammy D.

    1988-05-01

    Semiconductor structures in lower dimensions, dubbed quantum dots, exhibit novel properties which result from size quantization of their charge carriers, as well as from their large surface-to-volume ratio. Optical measurements, combined with scanning tunneling microscopy, can provide the detailed information required to model the nonlinear optical response of these clusters.

  11. Multiresonant two-photon-absorption-induced four wave mixing in crystalline rare earth insulators

    SciTech Connect

    Cone, R.L.; Ender, D.A.; Otteson, M.S.; Fisher, P.L.; Friedman, J.M.; Guggenheim, H.J.

    1982-01-01

    Coherent nonlinear optical generation of omega/sub 4/ = omega/sub 1/ + omega/sub 2/- omega/sub 3/ exhibits strong sharp intermediate (omega/sub 1/) and two-photon (omega/sub 1/ + omega /sub 2/) resonances in crystalline Tb(OH)/sub 3/ and LiTbF/sub 4/, providing a novel method for high resolution coherent measurement of both excited electronic configurations and intermediate 4f/sup n/ states of rare earth ions. New regions of the UV and VUV are thus made accessible to existing tuneable visible and near ultraviolet lasers. Selection of sharp features from broad overlapping absorptions, line narrowing due to phase matching selectivity, and coherent transient applications are discussed.

  12. Four-Wave Mixing and Optical Phase Conjugation in Vertical Cavity Surface Emitting Devices

    DTIC Science & Technology

    1997-01-01

    1990). Osinski , Marek and Jens Buus. "Linewidth Broadening Factor in Semiconductor Lasers- An Overview," IEEE Journal of Quantum Electronics QE-23(1): 9...above threshold. But as pointed out in the definitive document on the linewidth enhancement factor ( Osinski , 1987), for low carrier densities one can

  13. Geometries for the coherent control of four-wave mixing in graphene multilayers

    PubMed Central

    Rao, Shraddha M.; Lyons, Ashley; Roger, Thomas; Clerici, Matteo; Zheludev, Nikolay I.; Faccio, Daniele

    2015-01-01

    Deeply sub-wavelength two-dimensional films may exhibit extraordinarily strong nonlinear effects. Here we show that 2D films exhibit the remarkable property of a phase-controllable nonlinearity, i.e., the amplitude of the nonlinear polarisation wave in the medium can be controlled via the pump beam phase and determines whether a probe beam will “feel” or not the nonlinearity. This is in stark contrast to bulk nonlinearities where propagation in the medium averages out any such phase dependence. We perform a series of experiments in multilayer graphene that highlight some of the consequences of the optical nonlinearity phase-dependence, such as the coherent control of nonlinearly diffracted beams, single-pump-beam induced phase-conjugation and the demonstration of a nonlinear mirror characterised by negative reflection. The observed phase sensitivity is not specific to graphene but rather is solely a result of the dimensionality and is therefore expected in all 2D materials. PMID:26486075

  14. Experimental method for the determination of two-photon cross sections using four-wave mixing

    NASA Technical Reports Server (NTRS)

    Burris, J.; Mcilrath, T. J.

    1985-01-01

    The two-photon absorption cross section for the R22 + S12(J double prime = 9 1/2) transition in nitric oxide's gamma band has been determined. The value is in good agreement with previous measurements on several other NO transitions. The technique described here can be used to obtain accurate cross sections for other diatomic molecules.

  15. Dissecting X-Ray Raman Resonances Using Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Biggs, Jason D.; Zhang, Yu; Healion, Daniel; Govind, Niranjan; Shaul, Mukamel

    2013-03-01

    The stimulated x-ray Raman signal has been calculated for the amino acid cysteine using broadband (FWHM ≃14.2eV, 128 as) pulses tuned to the nitrogen K-edge. Peaks correspond to those valence excited states and reveal electronic Frank-Condon overlaps between canonical valence orbitals and relaxed orbitals in the presence of the core hole. The coupling between excited states with valence- and core-holes is further explored using a coherent, wave-vector matched photon echo technique, where it is possible to eliminate stimulated emission and excited-state absorption by taking the waiting time to be longer the lifetime of the core hole (˜ 7:1 fs for nitrogen).

  16. Measurement of the second order molecular hyperpolarizability of C 60- by nondegenerate four-wave mixing

    NASA Astrophysics Data System (ADS)

    Lascola, Robert; Wright, John C.

    1997-04-01

    We have determined the second order molecular hyperpolarizability γ for the charged species C 60- by use of coherent anti-Stokes Raman spectroscopy (CARS) vibrational lineshape analysis. We find γ is 2.4 (± 1.0) × 10 -33 esu, a value that is >65 times larger than the corresponding value for the neutral species and is comparable to values for highly conjugated organic polymers like polydiacetylene. The observed increase in γ with addition of charge to the fullerene cage has encouraging implications for the use of charge-transfer and endohedral fullerene complexes in future photonics devices.

  17. Optical Phase Conjugation via Four-Wave Mixing in Barium Titanate.

    DTIC Science & Technology

    1986-03-01

    light will now have more electric 39 S.. ... charge, and upon heating, electrostatic attraction will squeeze the thermoplastic film thinner than dark...direction of propagation and the phase factor of the electromagnetic wave. This causes the light to retrace its path, and as such has been referred...to as a "perfect mirror". Ordinary mirrors reverse the sign of only the normal component of the propagation vector k, causing light to reflect so that

  18. Nonlinear optical properties of porphyrin and chlorophyll dimers studied by degenerated four wave mixing

    SciTech Connect

    Chen, L.X.Q.

    1992-01-01

    As one of the important elements in natural and artificial electron transfer and energy transfer processes, porphyrin and its derivatives have received much attention in photoelectronics and photoelectronic materials. As our first attempt to relate the [pi]-[pi] electronic couplings between porphyrin macrocycles to apparent third order nonlinear susceptibilities, we measured [chi]([sup 3]) for several porphyrin and chlorophyll a derivatives, including dimers with different configurations. Our preliminary results show that the dimers have enhanced [chi]([sup 3]) compared to those of the monomer. This enhancement is related to the relative orientations between the two macrocycles in the dimers. The parallel dimers with close face-to-face distances seem to have the highest enhancement in [chi]([sup 3]). Thus, we believe that [chi]([sup 3]) is strongly related to the [pi]-[pi] electronic coupling between the two conjugated ring systems.

  19. Nonlinear optical properties of porphyrin and chlorophyll dimers studied by degenerated four wave mixing

    SciTech Connect

    Chen, L.X.Q.

    1992-12-31

    As one of the important elements in natural and artificial electron transfer and energy transfer processes, porphyrin and its derivatives have received much attention in photoelectronics and photoelectronic materials. As our first attempt to relate the {pi}-{pi} electronic couplings between porphyrin macrocycles to apparent third order nonlinear susceptibilities, we measured {chi}({sup 3}) for several porphyrin and chlorophyll a derivatives, including dimers with different configurations. Our preliminary results show that the dimers have enhanced {chi}({sup 3}) compared to those of the monomer. This enhancement is related to the relative orientations between the two macrocycles in the dimers. The parallel dimers with close face-to-face distances seem to have the highest enhancement in {chi}({sup 3}). Thus, we believe that {chi}({sup 3}) is strongly related to the {pi}-{pi} electronic coupling between the two conjugated ring systems.

  20. Diffractive optics based four-wave, six-wave, ..., nu-wave nonlinear spectroscopy.

    PubMed

    Miller, R J Dwayne; Paarmann, Alexander; Prokhorenko, Valentyn I

    2009-09-15

    A detailed understanding of chemical processes requires information about both structure and dynamics. By definition, a reaction involves nonstationary states and is a dynamic process. Structure describes the atomic positions at global minima in the nuclear potential energy surface. Dynamics are related to the anharmonicities in this potential that couple different minima and lead to changes in atomic positions (reactions) and correlations. Studies of molecular dynamics can be configured to directly access information on the anharmonic interactions that lead to chemical reactions and are as central to chemistry as structural information. In this regard, nonlinear spectroscopies have distinct advantages over more conventional linear spectroscopies. Because of this potential, nonlinear spectroscopies could eventually attain a comparable level of importance for studying dynamics on the relevant time scales to barrier crossings and reactive processes as NMR has for determining structure. Despite this potential, nonlinear spectroscopy has not attained the same degree of utility as linear spectroscopy largely because nonlinear studies are more technically challenging. For example, unlike the linear spectrometers that exist in almost all chemistry departments, there are no "black box" four-wave mixing spectrometers. This Account describes recent advances in the application of diffractive optics (DOs) to nonlinear spectroscopy, which reduces the complexity level of this technology to be closer to that of linear spectroscopy. The combination of recent advances in femtosecond laser technology and this single optic approach could bring this form of spectroscopy out of the exclusive realm of specialists and into the general user community. However, the real driving force for this research is the pursuit of higher sensitivity limits, which would enable new forms of nonlinear spectroscopy. This Account chronicles the research that has now extended nonlinear spectroscopy to six

  1. Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

    ERIC Educational Resources Information Center

    Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

    2005-01-01

    The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

  2. Applying Chemical Potential and Partial Pressure Concepts to Understand the Spontaneous Mixing of Helium and Air in a Helium-Inflated Balloon

    ERIC Educational Resources Information Center

    Jee-Yon Lee; Hee-Soo Yoo; Jong Sook Park; Kwang-Jin Hwang; Jin Seog Kim

    2005-01-01

    The spontaneous mixing of helium and air in a helium-inflated balloon is described in an experiment in which the partial pressure of the gases in the balloon are determined from the mole factions and the total pressure measured in the balloon. The results described provide a model for teaching concepts of partial pressure, chemical potential, and…

  3. Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

    NASA Astrophysics Data System (ADS)

    Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

    2011-03-01

    In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

  4. Spontaneous adsorption of coiled-coil model peptides K and E to a mixed lipid bilayer.

    PubMed

    Pluhackova, Kristyna; Wassenaar, Tsjerk A; Kirsch, Sonja; Böckmann, Rainer A

    2015-03-26

    A molecular description of the lipid-protein interactions underlying the adsorption of proteins to membranes is crucial for understanding, for example, the specificity of adsorption or the binding strength of a protein to a bilayer, or for characterizing protein-induced changes of membrane properties. In this paper, we extend an automated in silico assay (DAFT) for binding studies and apply it to characterize the adsorption of the model fusion peptides E and K to a mixed phospholipid/cholesterol membrane using coarse-grained molecular dynamics simulations. In addition, we couple the coarse-grained protocol to reverse transformation to atomistic resolution, thereby allowing to study molecular interactions with high detail. The experimentally observed differential binding of the peptides E and K to membranes, as well as the increased binding affinity of helical over unstructered peptides, could be well reproduced using the polarizable Martini coarse-grained (CG) force field. Binding to neutral membranes is shown to be dominated by initial binding of the positively charged N-terminus to the phospholipid headgroup region, followed by membrane surface-aligned insertion of the peptide at the interface between the hydrophobic core of the membrane and its polar headgroup region. Both coarse-grained and atomistic simulations confirm a before hypothesized snorkeling of lysine side chains for the membrane-bound state of the peptide K. Cholesterol was found to be enriched in peptide vicinity, which is probably of importance for the mechanism of membrane fusion. The applied sequential multiscale method, using coarse-grained simulations for the slow adsorption process of peptides to membranes followed by backward transformation to atomistic detail and subsequent atomistic simulations of the preformed peptide-lipid complexes, is shown to be a versatile approach to study the interactions of peptides or proteins with biomembranes.

  5. Measurement of mixing-induced thermal non-equilibrium in a supersonic shear layer using spontaneous Raman scattering

    NASA Astrophysics Data System (ADS)

    Reising, Heath H.; KC, Utsav; Clemens, Noel T.; Varghese, Philip L.

    2017-07-01

    Mixing-induced vibrational non-equilibrium of N2 is studied in the turbulent shear layer between a supersonic cold jet and a surrounding hot air coflow. The jet fluid is either air, N2, or Ar, and the heated coflow is air at a maximum temperature of 850 K. The rotational and vibrational temperatures of N2 are determined by fitting the measured time-averaged spontaneous Raman spectra to an analytical model that allows for different equilibrium distributions for the vibrational and rotational states. The mixing of the jet fluid with the coflow gases occurs over time scales of the order of 5 μs, which is found to be sufficiently fast to induce vibrational non-equilibrium in the mixture of hot and cold gases. Results show that the non-equilibrium can be measured, but not on the cold side of the shear layer where the vibrational population in the first hot band is negligible. The effect of fluctuating temperatures within the time-averaged Raman measurement was quantified with the use of Rayleigh thermometry and found to not significantly alter the Raman scattering results. It was also found that the non-equilibrium increases in the shear layer when N2 is removed from the jet fluid, indicating that the observed non-equilibrium is an averaged result of two competing processes that occur simultaneously at a molecular scale, i.e., vibrationally hot N2 is being cooled by a fast jet fluid and vibrationally cold jet fluid is being heated by a hot coflow fluid. An interesting inference of this view is that the averaging effect is always present, regardless of the measurement resolution.

  6. Comparative analysis of the use of various solid-state laser media for the self-starting of four-wave PCW generation in a loop laser resonator

    SciTech Connect

    Smetanin, Sergei N

    2013-01-31

    A generalised theory has been used to carry out a comparative analysis of the use of various four-level and quasi-threelevel media for the self-starting of degenerate four-wave mixing PCW generation directly in a laser medium placed in a loop resonator. It has been shown that quasi-three-level media can compete with four-level media at long upper laser level lifetimes and increased pump intensities. The most attractive solid-state laser media for four-wave PCW generation have been identified that have the highest deposited energy at a given pump intensity. In addition to neodymium-doped crystals, which are already widely used for four-wave PCW generation, promising materials are fourlevel chromium-doped media, e.g. alexandrite and Cr : LiCAF, and quasi-three-level media with the longest upper laser level lifetime, such as Yb : YAG and Tm, Ho : YAG, at high pump intensities. (nonlinear optical phenomena)

  7. A CRITICAL TEST OF VIBRATIONAL DEPHASING THEORIES IN SOLIDS USING SPONTANEOUS RAMAN SCATTERING IN ISOTOPICALLY MIXED CRYSTALS

    SciTech Connect

    Marks, S.; Cornelius, P.A.; Harris, C.B.

    1980-04-01

    A series of experiments has been conducted in order to evaluate the relative importance of several recent theories of vibrational dephasing in solids. The theories are discussed briefly, and are used to interpret the temperature dependence of the C-H and C-D stretch bands in the spontaneous Raman spectra of h{sub 14} - and d{sub 14}-1,2,4,5-tetramethyl benzene (durene). The infrared spectra of these same molecules are also reported in the region of the combination bands involving C-H (or C-D) stretches and low-frequency modes. The results support the applicability of the model of Harris, et. al., based on energy exchange in anharmonically coupled low-frequency modes. This theory is then used, in connection with Raman spectra obtained in isotopically mixed samples of durene, to elucidate the vibrational dynamics underlying the dephasing. It is found that the results are consistent with the hypothesis that some low-frequency modes in this molecule are significantly delocalized or 'excitonic' in character, and that this delocalization may be studied by means of a Raman spectroscopy on the low-frequency modes themselves, as well as by exchange analysis of the coupled high-frequency modes. These conclusions represent a generalization and extension of the previously published exchange model.

  8. A Generalized Multiple Discrete Interaction Approximation for resonant four-wave interactions in wind wave models

    NASA Astrophysics Data System (ADS)

    Tolman, Hendrik L.

    2013-10-01

    For several decades, the Discrete Interaction Approximation (DIA) for nonlinear resonant four-wave interactions has been the engine of third-generation wind-wave models. The present study presents a Generalized Multiple DIA (GMD) which expands upon the DIA by (i) expanding the definition of the representative quadruplet, (ii) formulating the DIA for arbitrary water depths, (iii) providing complimentary deep and shallow water scaling terms and (iv) allowing for multiple representative quadruplets. The GMD is rigorously derived to be an extension of the DIA, and is backward compatible with it. The free parameters of the GMD are optimized holistically, by optimizing full model behavior in the WAVEWATCH III® wave model as reported in a companion paper. Here, a cascade of GMD configurations with increasing complexity, accuracy and cost is presented. First, the performance of these configurations is discussed using idealized test cases used to optimize the GMD. It is shown that in deep water, GMD configurations can be found which remove most of the errors of the DIA. The GMD is also capable of representing four-wave interactions in extremely shallow water, although some remaining spurious behavior makes applications of this part of the GMD less suitable for operational wave models. Finally, several GMD configurations are applied to an idealized hurricane case, showing that results from idealized test cases indeed are representative for real-world applications, and confirming that such GMD configurations are economically feasible in operational wind wave models. Finally, the DIA results in surprisingly large model errors in hurricane conditions.

  9. Ultrabroadband mid-infrared spectroscopy with four-wave difference frequency generation

    NASA Astrophysics Data System (ADS)

    Fuji, Takao; Shirai, Hideto; Nomura, Yutaka

    2015-09-01

    Four-wave difference frequency generation (FWDFG) is a third-order optical parametric process, which is generally explained as {ω }1+{ω }2-{ω }3\\to {ω }4 or {ω }1-{ω }2-{ω }3\\to {ω }4, where three input frequencies are {ω }1, {ω }2, and {ω }3, and the output frequency is {ω }4. Here we report the use of FWDFG for chirped-pulse upconversion (CPU) of an ultrabroadband mid-infrared (MIR) supercontinuum and the application of the technique for MIR spectroscopy. When the CPU technique is used for MIR spectroscopy, ultrashort MIR pulses are converted into visible ones. This way, the spectra can be recorded with a visible spectrometer, which has much higher performance than MIR spectrometers. In the previous experiments, the CPU has been performed by using sum-frequency generation (SFG) with a solid crystal, and the bandwidth has been limited to less than 1000 cm-1 due to the phase matching condition of the SFG. This limitation can be removed by using FWDFG, which is a third-order nonlinear process that allows us to use centrosymmetric nonlinear media such as gases for the upconversion. Since gaseous media have much less dispersion than solid media, the bandwidth of the phase-matching condition for the upconversion process becomes very broad. In our experiments, the entire spectrum of the MIR supercontinuum spanning from 200 to 5500 cm-1 was upconverted by using a 4.9 ps chirped pulse to visible wavelength radiation, which was detected with a conventional visible dispersive spectrometer. The technique has been applied to attenuated total reflectance MIR spectroscopy. Absorption spectra of liquids in the range from 200 to 5500 cm-1 were measured with a visible spectrometer on a single-shot basis.

  10. Haldane Phases and Ferrimagnetic Phases with Spontaneous Translational Symmetry Breakdown in Distorted Mixed Diamond Chains with Spins 1 and 1/2

    NASA Astrophysics Data System (ADS)

    Hida, Kazuo; Takano, Ken'ichi; Suzuki, Hidenori

    2010-11-01

    The ground states of two types of distorted mixed diamond chains with spins 1 and 1/2 are investigated using exact diagonalization, DMRG, and mapping onto low-energy effective models. In the undistorted case, the ground state consists of an array of independent spin-1 clusters separated by singlet dimers. The lattice distortion induces an effective interaction between cluster spins. When this effective interaction is antiferromagnetic, several Haldane phases appear with or without spontaneous translational symmetry breakdown (STSB). The transition between the Haldane phase without STSB and that with (n+1)-fold STSB (n=1, 2, and 3) belongs to the same universality class as the (n+1)-clock model. In contrast, when the effective interaction is ferromagnetic, the quantized and partial ferrimagnetic phases appear with or without STSB. An effective low-energy theory for the partial ferrimagnetic phase is presented.

  11. Distinguishing non-resonant four-wave-mixing noise in coherent stokes and anti-stokes Raman scattering

    NASA Technical Reports Server (NTRS)

    Marks, Daniel L. (Inventor); Boppart, Stephen A. (Inventor)

    2009-01-01

    A method of examining a sample comprises exposing the sample to a pump pulse of electromagnetic radiation for a first period of time, exposing the sample to a stimulant pulse of electromagnetic radiation for a second period of time which overlaps in time with at least a portion of the first exposing, to produce a signal pulse of electromagnetic radiation for a third period of time, and interfering the signal pulse with a reference pulse of electromagnetic radiation, to determine which portions of the signal pulse were produced during the exposing of the sample to the stimulant pulse. The first and third periods of time are each greater than the second period of time.

  12. Four-wave-mixing spectroscopy of peridinin in solution and in the peridinin-chlorophyll- a protein

    NASA Astrophysics Data System (ADS)

    Christensson, Niklas; Chábera, Pavel; Hiller, Roger G.; Pullerits, Tõnu; Polívka, Tomáš

    2010-07-01

    A model for the third order optical response of carotenoids is used to analyse transient grating and pump-probe data of peridinin in solution and bound in the peridinin-chlorophyll protein (PCP). For peridinin in solution, the transient grating signal detected at 505 nm exhibits a bi-exponential recovery whose fast phase is assigned to relaxation from the S 2 state that has a lifetime of 75 ± 25 fs. The slower, solvent-dependent rise component is assigned to equilibration of the (S 1/ICT) state, taking place on a time scale of 0.6 and ˜2.5 ps in acetontrile and benzene, respectively. These dynamics match those obtained from pump-probe measured in the spectral region of the ICT state, implying that the ICT state contributes to the signal at 505 nm. In PCP, the transient grating signal shows distinctly different kinetics, and the signal shows no recovery. This difference is explained by energy transfer from peridinin to chlorophyll- a.

  13. Design of photonic crystal fibers with highly nonlinear glasses for four-wave-mixing based telecom applications.

    PubMed

    Kanka, Jiri

    2008-12-08

    A fully-vectorial mode solver based on the finite element method is employed in a combination with the downhill simplex method the dispersion optimization of photonic crystal fibers made from highly nonlinear glasses. The nonlinear fibers are designed for telecom applications such as parametric amplification, wavelength conversion, ultra-fast switching and regeneration of optical signals. The optimization is carried in terms of the zero dispersion wavelength, dispersion magnitude and nonlinear coefficient and confinement loss in the wavelength range around 1.55 microm. We restrict our work to the index-guiding fiber structures a small number of hexagonally arrayed air holes.

  14. Degenerate four-wave mixing spectroscopy and spectral simulation of C2 in an atmospheric pressure oxy-acetylene flame

    NASA Astrophysics Data System (ADS)

    Kaminski, C. F.; Hughes, I. G.; Ewart, P.

    1997-04-01

    The d 3Πg↔a3Πu Swan bands of C2 have been recorded with high resolution using DFWM in the nearly Doppler free, phase conjugate geometry. C2 was probed in a standard oxy-acetylene welding flame with excellent signal-to-noise ratio and spectral resolution. Theoretical spectra were simulated and fitted directly to the complex overlapping spectra. The good agreement obtained shows that DFWM holds promise to become a robust and reliable tool for flame thermometry. Current theories of DFWM are reviewed in context of the present work and advantages and disadvantages of the technique are discussed.

  15. Modulating the correlation and squeezing of phase-conjugate four-wave mixing via the polarizable dressing states.

    PubMed

    Wang, Ruimin; Guo, Yao; Liu, Zheng; Ma, Jiaqi; Yin, Ming; Wang, Xiuxiu; Li, Changbiao; Zhang, Yanpeng

    2015-05-28

    We report the experimental observation of the intensity noise correlation and squeezing between counter propagating Stokes and anti-Stokes signals in Pr(3+):Y2SiO5 crystals. Both the degree of correlation and squeezing as well as the oscillation frequency of correlation curves are modulated by changing the polarization states and powers of the dressing fields. The double-dressed effect and the triple-dressed effect in V-type three-level, Λ-type three-level and N-type four-level systems are compared. The polarization and power dependencies in these systems are different, and the oscillation frequency of the correlation curve in the triple-dressed process is greater than that of the double-dressed process. Our results show that the correlation and squeezing of photon pairs can be controlled via polarized dark states.

  16. Two-color interference effect involving three-photon atomic excitation and four-wave mixing in crossed laser beams

    SciTech Connect

    Peet, V.

    2007-09-15

    Through multiphoton ionization measurements, the polarization effects in destructive quantum interference under three-photon resonant excitation have been studied. Recent observations [V. Peet, Phys. Rev. A 74, 033406 (2006)] have indicated that contrary to the well-known pattern of a total suppression of resonance excitation, the destructive interference becomes incomplete if three-photon transition is driven by crossed beams with orthogonal polarization planes. These observations have been tested for a more general case of two-color excitation and very similar polarization-dependent anomalies in the interference character have been registered. It has been shown that the destructive interference is modified and the resonance excitation does occur if two crossed laser beams have opposite circular polarizations. The pressure-induced evolution of the uncanceled ionization peaks has the ratio of blue shift to width close to 0.5 exactly as it is known for resonance ionization peaks registered under excitation by counterpropagating laser beams.

  17. Nonlinear Optics Technology. Phase 2. Area 1. Four Wave Mixing Technology. Area 2. Phase Conjugated Solid State Laser Technology

    DTIC Science & Technology

    1988-01-15

    particle - in - a - box model for MQWs...the system. E GoAsg C 56 c1 irges in the band gap physics. Temporarily ignoring the effects of the e-h Coulomb interaction, simple particle - in - a - box theory...and 0 is the Heaviside step function. Figure 3-17C shows schematically the particle in a box energy levels and wave functions for both the

  18. Interplay of phase-sensitive amplification and cascaded four-wave mixing in dispersion-controlled waveguides

    NASA Astrophysics Data System (ADS)

    Martin, Aude; Combrié, Sylvain; Willinger, Amnon; Eisenstein, Gadi; de Rossi, Alfredo

    2016-08-01

    Phase-sensitive parametric interactions can selectively process the two complex quadratures of the optical field. We implement phase-sensitive amplification in a large band-gap semiconductor photonic crystal waveguide in order to avoid two-photon absorption and free-carrier-related effects. Experimentally, an extinction ratio of 15 dB is achieved in a 1.5-mm-long photonic crystal waveguide, at a peak pump power of about 600 mW. We show that cascaded parametric interaction has a strong impact on squeezing and phase-sensitive extinction ratio and that this depends on the dispersion profile of the waveguide.

  19. Supercontinuum and four-wave mixing with Q-switched pulses in endlessly single-mode photonic crystal fibres.

    PubMed

    Wadsworth, W; Joly, N; Knight, J; Birks, T; Biancalana, F; Russell, P

    2004-01-26

    Photonic crystal fibres exhibiting endlessly single-mode operation and dispersion zero in the range 1040 to 1100 nm are demonstrated. A sub-ns pump source at 1064 nm generates a parametric output at 732 nm with an efficiency of 35%, or parametric gain of 55 dB at 1315 nm. A broad, flat supercontinuum extending from 500 nm to beyond 1750 nm is also demonstrated using the same pump source.

  20. A 21-35 kDa Mixed Protein Component from Helicobacter pylori Activates Mast Cells Effectively in Chronic Spontaneous Urticaria.

    PubMed

    Tan, Ran-Jing; Sun, He-Qiang; Zhang, Wei; Yuan, Han-Mei; Li, Bin; Yan, Hong-Tao; Lan, Chun-Hui; Yang, Jun; Zhao, Zhuo; Wu, Jin-Jin; Wu, Chao

    2016-12-01

    Helicobacter pylori (H. pylori) seem to involve in the etiology of chronic spontaneous urticaria (CSU). But studies of the pathogenic mechanism are very little. In this study, we detected the serum-specific anti-H. pylori IgG and IgE antibodies in 211 CSU and 137 normal subjects by enzyme-linked immunosorbent assay (ELISA), evaluated the direct activation effects of H. pylori preparations and its protein components on human LAD2 mast cell line in vitro, and analyzed the specific protein ingredients and functions of the most effective H. pylori mixed protein component using liquid chromatography-mass spectrometry and ELISA assay. In CSU patients, the positive rate of anti-H. pylori IgG positive rate was significantly higher than that in normal controls, and the anti-H. pylori IgE levels had no statistical difference between H. pylori-infected patients with and without CSU. Further studies suggested that H. pylori preparations can directly activate human LAD2 mast cell line in a dose-dependent manner and its most powerful protein component was a mixture of 21-35 kDa proteins. Moreover, the 21-35 kDa mixed protein component mainly contained 23 kinds of proteins, which can stimulate the release of histamine, TNF-a, IL-3, IFN-γ, and LTB4 by LAD2 cells in a dose-dependent or time-dependent manner. A 21-35 kDa mixed protein component should be regarded as the most promising pathogenic factor contributing to the CSU associated with H. pylori infection. © 2016 John Wiley & Sons Ltd.

  1. Phase Coupling in Langmuir Wave Packets: Evidence for Four Wave Interactions in Solar Type III Radio Bursts

    NASA Technical Reports Server (NTRS)

    Thejappa, G.; MacDowall, R. J.; Bergamo, M.

    2012-01-01

    The four wave interaction process, known as the oscillating two stream instability (OTSI) is considered as one of the mechanisms responsible for stabilizing the electron beams associated with solar type III radio bursts. It has been reported that (1) an intense localized Langmuir wave packet associated with a type III burst contains the spectral characteristics of the OTSI: (a) a resonant peak at the local electron plasma frequency, f(sub pe), (b) a Stokes peak at a frequency slightly lower than f(sub pe), (c) anti-Stokes peak at a frequency slightly higher than f(sub pe), and (d) a low frequency enhancement below a few hundred Hz, (2) the frequencies and wave numbers of these spectral components satisfy the resonance conditions of the OTSI, and (3) the peak intensity of the wave packet is well above the thresholds for the OTSI as well as spatial collapse of envelope solitons. Here, for the first time, applying the trispectral analysis on this wave packet, we show that the tricoherence, which measures the degree of coherent four-wave coupling amongst the observed spectral components exhibits a peak. This provides an additional evidence for the OTSI and related spatial collapse of Langmuir envelope solitons in type III burst sources.

  2. Relations between Political Violence and Child Adjustment: A Four-Wave Test of the Role of Emotional Insecurity about Community

    PubMed Central

    Cummings, E. Mark; Taylor, Laura K.; Merrilees, Christine E.; Goeke-Morey, Marcie C.; Shirlow, Peter; Cairns, Ed

    2015-01-01

    This study further explored the impact of sectarian violence and children’s emotional insecurity about community on child maladjustment using a four-wave longitudinal design. The study included 999 mother-child dyads in Belfast, Northern Ireland (482 boys, 517 girls). Across the four-waves, child mean age was 12.19 (SD = 1.82), 13.24 (SD = 1.83), 13.61 (SD = 1.99), and 14.66 years (SD = 1.96), respectively. Building on previous studies of the role of emotional insecurity in child adjustment, the current study examines within-person change in emotional insecurity using latent growth curve analyses. The results showed that children’s trajectories of emotional insecurity about community were related to risk for developing conduct and emotion problems. These findings controlled for earlier adjustment problems, age and gender, and took into account the time-varying nature of experience with sectarian violence. Discussion considers the implications for children’s emotional insecurity about community for relations between political violence and children’s adjustment, including the significance of trajectories of emotional insecurity over time. PMID:23527495

  3. Exploring changes in nursing students' attitudes towards the use of technology: A four-wave longitudinal panel study.

    PubMed

    Tubaishat, Ahmad; Aljezawi, Ma'en; Al-Rawajfah, Omar M; Habiballah, Laila; Akhu-Zaheya, Laila M

    2016-03-01

    It is essential for nursing students to be equipped with the necessary technology skills throughout and after their study period. Their acceptance of this technology depends largely on their attitudes towards technology. To explore the evolution in nursing students' attitudes towards technology, and to determine whether there was a change in participants' formal education in technology over their four years of study. A longitudinal panel study was conducted in a single school of nursing in Jordan. A total of 140 students were followed over their four years of undergraduate study. They completed the same tool (the Technology Attitude Scale) each year, to capture any changes in their attitudes towards technology across the years. In all four waves of data collection, students showed positive attitudes towards technology, with the highest attitude scores being in their final year (M=6.19, SD=0.72). As the students spent more time on their nursing education, they were found to have a more positive attitude. Thus, a strong positive relationship existed between this formal education in technology and attitudes: as the students' education in technology increased, their attitudes were more positive. A remarkable development in students' attitudes towards technology is reported in this study. The positive attitudes displayed by the students should be enhanced by providing technology-related subjects during their studies in nursing schools at a very early stage. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Spontaneous Fission

    DOE R&D Accomplishments Database

    Segre, Emilio

    1950-11-22

    The first attempt to discover spontaneous fission in uranium was made by [Willard] Libby, who, however, failed to detect it on account of the smallness of effect. In 1940, [K. A.] Petrzhak and [G. N.] Flerov, using more sensitive methods, discovered spontaneous fission in uranium and gave some rough estimates of the spontaneous fission decay constant of this substance. Subsequently, extensive experimental work on the subject has been performed by several investigators and will be quoted in the various sections. [N.] Bohr and [A.] Wheeler have given a theory of the effect based on the usual ideas of penetration of potential barriers. On this project spontaneous fission has been studied for the past several years in an effort to obtain a complete picture of the phenomenon. For this purpose the spontaneous fission decay constants {lambda} have been measured for separated isotopes of the heavy elements wherever possible. Moreover, the number {nu} of neutrons emitted per fission has been measured wherever feasible, and other characteristics of the spontaneous fission process have been studied. This report summarizes the spontaneous fission work done at Los Alamos up to January 1, 1945. A chronological record of the work is contained in the Los Alamos monthly reports.

  5. Brillouin-enhanced four-wave-mixing phase conjugator with correction for material, thermal and birefringence aberrations and passive output control

    SciTech Connect

    Bowers, M.W.; Hankla, A.K.; Boyd, R.W.

    1995-11-20

    We have developed a laser system that incoroprates a vector phase conjugate mirror that corrects for both spatial and polarization distortions. The fractional output coupling can be varied mechanically from 0 to 100%.

  6. Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

    NASA Astrophysics Data System (ADS)

    Lempert, Walter R.; Adamovich, Igor V.

    2014-10-01

    The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed.

  7. Polarization dependence of nonlinear wave mixing of spinor polaritons in semiconductor microcavities

    NASA Astrophysics Data System (ADS)

    Lewandowski, Przemyslaw; Lafont, Ombline; Baudin, Emmanuel; Chan, Chris K. P.; Leung, P. T.; Luk, Samuel M. H.; Galopin, Elisabeth; Lemaître, Aristide; Bloch, Jacqueline; Tignon, Jerome; Roussignol, Philippe; Kwong, N. H.; Binder, Rolf; Schumacher, Stefan

    2016-07-01

    The pseudospin dynamics of propagating exciton-polaritons in semiconductor microcavities are known to be strongly influenced by TE-TM splitting. As a vivid consequence, in the Rayleigh scattering regime, the TE-TM splitting gives rise to the optical spin Hall effect (OSHE). Much less is known about its role in the nonlinear optical regime in which four-wave mixing, for example, allows the formation of spatial patterns in the polariton density, such that hexagons and two-spot patterns are observable in the far field. Here we present a detailed analysis of spin-dependent four-wave mixing processes, by combining the (linear) physics of TE-TM splitting with spin-dependent nonlinear processes, i.e., exciton-exciton interaction and fermionic phase-space filling. Our combined theoretical and experimental study elucidates the complex physics of the four-wave mixing processes that govern polarization and orientation of off-axis modes.

  8. Measurements of Electric Field in a Nanosecond Pulse Discharge by 4-WAVE Mixing

    NASA Astrophysics Data System (ADS)

    Baratte, Edmond; Adamovich, Igor V.; Simeni Simeni, Marien; Frederickson, Kraig

    2017-06-01

    Picosecond four-wave mixing is used to measure temporally and Picosecond four-wave mixing is used to measure temporally and spatially resolved electric field in a nanosecond pulse dielectric discharge sustained in room air and in an atmospheric pressure hydrogen diffusion flame. Measurements of the electric field, and more precisely the reduced electric field (E/N) in the plasma is critical for determination rate coefficients of electron impact processes in the plasma, as well as for quantifying energy partition in the electric discharge among different molecular energy modes. The four-wave mixing measurements are performed using a collinear phase matching geometry, with nitrogen used as the probe species, at temporal resolution of about 2 ns . Absolute calibration is performed by measurement of a known electrostatic electric field. In the present experiments, the discharge is sustained between two stainless steel plate electrodes, each placed in a quartz sleeve, which greatly improves plasma uniformity. Our previous measurements of electric field in a nanosecond pulse dielectric barrier discharge by picosecond 4-wave mixing have been done in air at room temperature, in a discharge sustained between a razor edge high-voltage electrode and a plane grounded electrode (a quartz plate or a layer of distilled water). Electric field measurements in a flame, which is a high-temperature environment, are more challenging because the four-wave mixing signal is proportional to the to square root of the difference betwen the populations of N2 ground vibrational level (v=0) and first excited vibrational level (v=1). At high temperatures, the total number density is reduced, thus reducing absolute vibrational level populations of N2. Also, the signal is reduced further due to a wider distribution of N2 molecules over multiple rotational levels at higher temperatures, while the present four-wave mixing diagnostics is using spectrally narrow output of a ps laser and a high

  9. Turbulence, Spontaneous Stochasticity and Climate

    NASA Astrophysics Data System (ADS)

    Eyink, Gregory

    Turbulence is well-recognized as important in the physics of climate. Turbulent mixing plays a crucial role in the global ocean circulation. Turbulence also provides a natural source of variability, which bedevils our ability to predict climate. I shall review here a recently discovered turbulence phenomenon, called ``spontaneous stochasticity'', which makes classical dynamical systems as intrinsically random as quantum mechanics. Turbulent dissipation and mixing of scalars (passive or active) is now understood to require Lagrangian spontaneous stochasticity, which can be expressed by an exact ``fluctuation-dissipation relation'' for scalar turbulence (joint work with Theo Drivas). Path-integral methods such as developed for quantum mechanics become necessary to the description. There can also be Eulerian spontaneous stochasticity of the flow fields themselves, which is intimately related to the work of Kraichnan and Leith on unpredictability of turbulent flows. This leads to problems similar to those encountered in quantum field theory. To quantify uncertainty in forecasts (or hindcasts), we can borrow from quantum field-theory the concept of ``effective actions'', which characterize climate averages by a variational principle and variances by functional derivatives. I discuss some work with Tom Haine (JHU) and Santha Akella (NASA-Goddard) to make this a practical predictive tool. More ambitious application of the effective action is possible using Rayleigh-Ritz schemes.

  10. Spontaneous pneumothorax in weightlifters.

    PubMed

    Marnejon, T; Sarac, S; Cropp, A J

    1995-06-01

    Spontaneous pneumothorax is infrequently caused by strenuous exertion. To our knowledge there has only been one case of spontaneous pneumothorax associated with weightlifting reported in the medical literature. We describe three consecutive cases of spontaneous pneumothorax associated with weightlifting. We postulate that spontaneous pneumothorax in these patients may be secondary to improper breathing techniques. It is important that physicians and weight trainers be aware of the association between weight lifting and spontaneous pneumothorax and assure that proper instruction is given to athletes who work with weights.

  11. Spontaneous EEG activity and spontaneous emotion regulation.

    PubMed

    Tortella-Feliu, M; Morillas-Romero, A; Balle, M; Llabrés, J; Bornas, X; Putman, P

    2014-12-01

    Variability in both frontal and parietal spontaneous EEG activity, using α and β band power and θ/β and δ/β ratios, was explored in a sample of 96 healthy volunteers as a potential correlate of individual differences in spontaneous emotion regulation (SER). Following a baseline EEG recording, participants were asked to continuously rate their discomfort while looking at affective pictures, as well as for a period of time after exposure. Greater spontaneous β band power in parietal locations, lower frontal and parietal δ/β ratios, and lower parietal θ/β ratio were associated with lower ratings of discomfort after the offset of unpleasant pictures. Moreover, lower parietal δ/β ratio was also related to less time needed to recover from discomfort after exposure to aversive pictures, while only a greater frontal and parietal α band power appeared to be associated with faster recovery from discomfort induced by normative-neutral pictures. However, parietal δ/β ratio was the only predictor of both minimum discomfort ratings and time needed to downregulate following exposure to unpleasant pictures, and frontal α band power the only spontaneous EEG index that predicted variability in spontaneous down-regulation after the exposure to normative-neutral pictures. Results are discussed focusing on the utility of diverse spontaneous EEG measures in several cortical regions when capturing trait-like individual differences in emotion regulation capabilities and processes. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Negative spontaneous magnetization and semi-spin glass magnetic order in mixed spinel Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4}

    SciTech Connect

    Gupta, Arti; Tandon, R. P.; Shinde, A. B.; Krishna, P. S. R.; Chatterjee, Ratnamala

    2015-10-07

    In this paper, we establish the negative spontaneous magnetization in Mn and Zn substituted cobalt ferrite Co{sub 0.6}Zn{sub 0.4}Fe{sub 1.7}Mn{sub 0.3}O{sub 4} (CZFMO). It is suggested that the origin of negative spontaneous magnetization is due to the substitution of small sized Mn{sup +4} ions (compared to Fe{sup +3} ions) at the octahedral B site in compound Co{sub 0.6}Zn{sub 0.4} Fe{sub 2}O{sub 4}. The low value of Poisson's ratio ∼0.202 for this compound possibly contributes towards the easy distortion in the bond length and bond angle, causing increase in Fe-O bond distance/decrease in Fe-O-Fe bond angle with Mn substitution, leading to considerably weak Fe-O-Fe superexchange interaction at the octahedral B site. The neutron diffraction data clearly illustrated the significant reduction in ordered magnetic moment at the B site, with the resultant negative spontaneous magnetization (M = M{sub B} − M{sub A}) in this mixed spinel system. The spin disorder also gives rise to an interesting semi-spin glass behavior in CZFMO.

  13. Wave mixing spectroscopy

    SciTech Connect

    Smith, R.W.

    1980-08-01

    Several new aspects of nonlinear or wave mixing spectroscopy were investigated utilizing the polarization properties of the nonlinear output field and the dependence of this field upon the occurrence of multiple resonances in the nonlinear susceptibility. First, it is shown theoretically that polarization-sensitive detection may be used to either eliminate or controllably reduce the nonresonant background in coherent anti-Stokes Raman spectroscopy, allowing weaker Raman resonances to be studied. The features of multi-resonant four-wave mixing are examined in the case of an inhomogeneously broadened medium. It is found that the linewidth of the nonlinear output narrows considerably (approaching the homogeneous width) when the quantum mechanical expressions for the doubly- and triply-resonant susceptibilities are averaged over a Doppler or strain broadened profile. Experimental studies of nonlinear processes in Pr/sup +3/:LaF/sub 3/ verify this linewidth narrowing, but indicate that this strain broadened system cannot be treated with a single broadening parameter as in the case of Doppler broadening in a gas. Several susceptibilities are measured from which are deduced dipole matrix elements and Raman polarizabilities related to the /sup 3/H/sub 4/, /sup 3/H/sub 6/, and /sup 3/P/sub 0/ levels of the praseodymium ions.

  14. Unified spontaneous Raman and CARS system

    NASA Astrophysics Data System (ADS)

    Lederman, S.; Posillico, C.

    1981-06-01

    In order to provide a more universally applicable diagnostic apparatus, a novel device based on simultaneous LDV and spontaneous Raman diagnostics is proposed. The simplest configuration of the device uses a Q-switched ruby laser and a Raman cell filled with a gas of particular interest, the Stokes line of which is stimulated. When the line is colinearly mixed with the primary beam, a coherent anti-Stokes Raman scattering (CARS) signal is generated in a given flowfield. A part of the incident ruby laser is simultaneously utilized to obtain spontaneous Raman signals, yielding the advantages of both the spontaneous and the CARS techniques using only one ruby laser. Experimental results demonstrate that the system can provide data on most practical flowfields, whether they are clean or contaminated and environmentally friendly or hostile.

  15. Spontaneous Resolution of Massive Spontaneous Tubercular Pneumothorax

    PubMed Central

    Kant, Surya; Saheer, S.; Hassan, G.; Parengal, Jabeed

    2011-01-01

    A 29-year-old female presented with complaints of fever and productive cough of three weeks duration. Pulmonary tuberculosis was diagnosed bacteriologically and she was prescribed antituberculosis drugs. During follow-up she developed massive pneumothorax, for which patient refused surgical management and was managed conservatively. After six months there was complete spontaneous resolution of pneumothorax. The unusual presentation and unexpected outcome prompted us to report this case. PMID:22937428

  16. Spontaneous Coronary Artery Dissection

    MedlinePlus

    ... artery dissection (SCAD). It's not yet clear what role these factors play in causing the disease. Common factors include: Female sex. Though spontaneous coronary artery dissection (SCAD) can occur ...

  17. Spontaneous combustion of hydrogen

    NASA Technical Reports Server (NTRS)

    Nusselt, Wilhelm; Pothmann, PH

    1923-01-01

    It is shown by the author's experiments that hydrogen which escapes to the atmosphere through openings in the system may burn spontaneously if it contains dust. Purely thermal reasoning can not account for the combustion. It seems to be rather an electrical ignition. In order to determine whether the cause of the spontaneous ignition was thermo-chemical, thermo-mechanical, or thermo-electrical, the experiments in this paper were performed.

  18. Spontaneous endomyometrial neoplasms in aging Chinese hamsters

    SciTech Connect

    Brownstein, D.G.; Brooks, A.L.

    1980-05-01

    Twenty-one endomyometrial neoplasms among 93 nulliparous noninbred Chinese hamsters were evaluated. The median survival time of the 93 females was 1040 days. The median age of hamsters with endomyometrial neoplasms was 1200 days. Neoplasms were classified as carcinomas or malignant mixed muellerian tumors of the endometrium and benign or malignant myometrial neoplasms. There were 13 endometrial adenocarcinomas. Three tumors were mixed adenosquamous carcinomas, which occurred in significantly older Chinese hamsters than did adenocarcinomas. Three malignant mixed muellerian tumors consisted of 2 carcinosarcomas and 1 mixed mesodermal tumor. The 2 myometrial neoplasms were a lelomyoma and a lelomyosarcoma. The classification and relative frequency of these neoplasms were similar to endomyometrial neoplasms of women, which makes Chinese hamsters useful subjects for studies of spontaneous endomyometrial cancers.

  19. Spontaneous closure of stoma.

    PubMed

    Pandit, Narendra; Singh, Harjeet; Kumar, Hemanth; Gupta, Rajesh; Verma, G R

    2016-11-01

    Intestinal loop stoma is a common surgical procedure performed for various benign and malignant abdominal problems, but it rarely undergoes spontaneous closure, without surgical intervention. Two male patients presented to our emergency surgical department with acute abdominal pain. One of them was diagnosed as having rectosigmoid perforation and underwent diversion sigmoid loop colostomy after primary closure of the perforation. The other was a known case of carcinoma of the rectum who had already undergone low anterior resection with covering loop ileostomy; the patient underwent second loop ileostomy, this time for complicated intestinal obstruction. To our surprise, both the loop colostomy and ileostomy closed spontaneously at 8 weeks and 6 weeks, respectively, without any consequences. Spontaneous stoma closure is a rare and interesting event. The exact etiology for spontaneous closure remains unknown, but it may be hypothesized to result from slow retraction of the stoma, added to the concept of a tendency towards spontaneous closure of enterocutaneous fistula. © The Author(s) 2015. Published by Oxford University Press and the Digestive Science Publishing Co. Limited.

  20. Solution study of a structurally characterized monoalkoxo-bound monooxo-vanadium(V) complex: spontaneous generation of the corresponding oxobridged divanadium(V,V) complex and its electroreduction to a mixed-valence species in solution.

    PubMed

    Dinda, Rupam; Sengupta, Parbati; Sutradhar, Manas; Mak, Thomas C W; Ghosh, Saktiprosad

    2008-07-07

    An interesting transformation of a structurally characterized monooxoalkoxovanadium(V) complex [VO(OEt)L] (LH 2 = a dibasic tridentate ONO donor ligand) in solution leading to the formation of the corresponding monooxobridged divanadium(V,V) complex (VOL) 2O is reported. This binuclear species in solution is adequately characterized by elemental analysis, measurement of conductance (in solution), various spectroscopic (UV-vis, IR, NMR, and mass spectrometry) techiniques and by cyclic voltammetry. The corresponding mixed-valence vanadium(IV,V) species has been generated in CH 3CN solution by controlled potential electrolysis of (VOL) 2O. This mixed-valence species is identified and studied by EPR technique (at room temperature and at liquid nitrogen temperature) and also by UV-vis spectroscopy. This study may be regarded as a general method of obtaining monooxo-bridged binuclear vanadium(V,V) species from the corresponding mononuclear monooxoalkoxovanadium(V) complexes of some selected dibasic tridentate ONO chelating ligands, which can be utilized as the precursor of monooxobridged divanadium(IV,V) mixed-valence species in solution obtainable by controlled potential electrolysis.

  1. Spontaneous vitrification in an immiscible Fe-Cu system

    NASA Astrophysics Data System (ADS)

    Huang, L. J.; Liu, B. X.

    1990-10-01

    Spontaneous vitrification was observed in the equilibrium immiscible Fe-Cu system. The metastable phase before vitrification was an icosahedral incommensurate phase which was formed by an ion beam mixing of Fe-Cu multilayer films at room temperature and subsequent high-temperature thermal annealing. The electrical and magnetic properties of the icosahedral phase are also reported, and the relation with spontaneous vitrification is discussed.

  2. Spontaneous Perforation of Pyometra

    PubMed Central

    Yildizhan, Begüm; Uyar, Esra; Şişmanoğlu, Alper; Güllüoğlu, Gülfem; Kavak, Zehra N.

    2006-01-01

    Pyometra is the accumulation of purulent material in the uterine cavity. Its reported incidence is 0.01−0.5% in gynecologic patients; however, as far as elderly patients are concerned, its incidence is 13.6% [3]. The most common cause of pyometra is malignant diseases of genital tract and the consequences of their treatment (radiotherapy). Other causes are benign tumors like leiomyoma, endometrial polyps, senile cervicitis, cervical occlusion after surgery, puerperal infections, and congenital cervical anomalies. Spontaneous rupture of the uterus is an extremely rare complication of pyometra. To our knowledge, only 21 cases of spontaneous perforation of pyometra have been reported in English literature since 1980. This paper reports an additional case of spontaneous uterine rupture. PMID:17093350

  3. Biomodal spontaneous fission

    SciTech Connect

    Hulet, E.K. )

    1989-09-26

    Investigations of mass and kinetic-energy distributions from spontaneous fission have been extended in recent years to an isotope of element 104 and, for half-lives, to an isotope of element 108. The results have been surprising in that spontaneous fission half-lives have turned out to be much longer than expected and mass and kinetic- energy distributions were found to abruptly shift away from those of the lighter actinides, showing two modes of fission. These new developments have caused a re-evaluation of our understanding of the fission process, bringing an even deeper appreciation of the role played by nuclear shell effects upon spontaneous fission properties. 16 refs., 10 figs.

  4. Spontaneous sarcomere dynamics

    NASA Astrophysics Data System (ADS)

    Günther, Stefan; Kruse, Karsten

    2010-12-01

    Sarcomeres are the basic force generating units of striated muscles and consist of an interdigitating arrangement of actin and myosin filaments. While muscle contraction is usually triggered by neural signals, which eventually set myosin motors into motion, isolated sarcomeres can oscillate spontaneously between a contracted and a relaxed state. We analyze a model for sarcomere dynamics, which is based on a force-dependent detachment rate of myosin from actin. Our numerical bifurcation analysis of the spontaneous sarcomere dynamics reveals notably Hopf bifurcations, canard explosions, and gluing bifurcations. We discuss possible implications for experiments.

  5. Spontaneous bilateral tubal pregnancy.

    PubMed

    Wali, Aisha Syed; Khan, Rozilla Sadia

    2012-02-01

    With the increase in incidence of ectopic pregnancy over the decades, bilateral ectopic pregnancy is also increasing. It is usually associated with assisted reproductive techniques (ART) but in recent years few cases of spontaneous bilateral ectopic pregnancy have been reported. Gynaecologists should be aware of this and that ultrasonography has limitations in diagnosis. In cases of ectopic pregnancy where contralateral adnexa is not clearly identified on ultrasound and fertility needs to be conserved, patient should be managed by experts in well equipped centres. A case of spontaneous bilateral tubal pregnancy that remained undiagnosed till laparotomy, is described.

  6. Autowaves in two-wave mixing in photorefractive media

    SciTech Connect

    Prudkovskii, Pavel A

    2011-01-31

    The phase part of the system of equations describing two-wave mixing in a photorefractive strongly inertial medium is studied analytically and numerically. It is shown that the solution of the system of equations evolves through a series of quasi-stationary states, and the system switches between them due to a nonlinear wave. The velocity and profile of such a 'switching wave' are completely determined by these states, which is an indication of an autowave process. The results show that the development of four-wave mixing in a strongly illuminated photorefractive medium is inevitably accompanied by intensity fluctuations. (nonlinear optical phenomena)

  7. Spontaneous polyploidization in cucumber

    USDA-ARS?s Scientific Manuscript database

    Cucumber occasionally produces polyploid plants, which are problematic for growers because these plants produce misshaped fruits with non-viable seeds. In this study, we undertook the first quantitative study to estimate the frequency of spontaneous polyploids in cucumber. Seeds of recombinant inbre...

  8. Spontaneous rib fractures.

    PubMed

    Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

    2015-07-01

    Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

  9. Spontaneous transverse colon volvulus

    PubMed Central

    Sana, Landolsi; Ali, Gassara; Kallel, Helmi; Amine, Baklouti; Ahmed, Saadaoui; Mohamed Ali, Elouer; Wajdi, Chaeib; Saber, Mannaï

    2013-01-01

    We report a case of spontaneous transverse colon volvulus in a young healthy woman. It constitutes an unusual case since it occurred in a young healthy woman with a subacute onset and no aetiological factor has been found. Its diagnosis is still challenging. Prompt recognition with emergency intervention constitutes the key to successful outcome. PMID:23785565

  10. Spontaneous transverse colon volvulus.

    PubMed

    Sana, Landolsi; Ali, Gassara; Kallel, Helmi; Amine, Baklouti; Ahmed, Saadaoui; Ali, Elouer Mohamed; Wajdi, Chaeib; Saber, Mannaï

    2013-01-01

    We report a case of spontaneous transverse colon volvulus in a young healthy woman. It constitutes an unusual case since it occurred in a young healthy woman with a subacute onset and no aetiological factor has been found. Its diagnosis is still challenging. Prompt recognition with emergency intervention constitutes the key to successful outcome.

  11. Spontaneous fulminant gas gangrene.

    PubMed

    Delbridge, M S; Turton, E P L; Kester, R C

    2005-07-01

    Gas gangrene is a rare condition, usually associated with contaminated traumatic injuries. It carries a high rate of mortality and morbidity. A number of studies have implicated non-traumatic gas gangrene and colonic neoplasia. This paper reports a patient who presented spontaneously with Clostridium septicum gas gangrene and an occult caecal carcinoma.

  12. [Spontaneous bacterial peritonitis].

    PubMed

    Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

    2017-01-01

    Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

  13. Spontaneous intracranial hypotension.

    PubMed Central

    Renowden, S A; Gregory, R; Hyman, N; Hilton-Jones, D

    1995-01-01

    The clinical features and radiological appearances of spontaneous intracranial hypotension are described in three patients and the medical literature is reviewed. Awareness of this condition and its differentiation from more sinister meningitic processes is important to avoid unnecessary invasive investigations and to allow prompt diagnosis and effective treatment. Images PMID:8530936

  14. Antenatal depressive symptoms as a predictor of deterioration in perceived social support across the perinatal period: a four-wave cohort study in Turkey.

    PubMed

    Senturk, V; Abas, M; Dewey, M; Berksun, O; Stewart, R

    2017-03-01

    In a perinatal cohort of women in urban and rural Turkey, we investigated associations between antenatal depressive symptoms and subsequent changes in perceived quality of key family relationships. Of 730 women recruited in their third trimester (94.6% participation), 578 (79.2%) were reassessed at a mean of 4.1 (s.d. = 3.3) months after childbirth, 488 (66.8%) were reassessed at 13.7 (s.d. = 2.9) months, and 448 (61.4%) at 20.8 (s.d. = 2.7) months. At all four examinations, self-reported quality of relationship with the husband, mother and mother-in-law was ascertained using the Close Persons Questionnaire with respect to emotional support, practical support and negative aspects of the relationship. Antenatal depressive symptoms were defined using the Edinburgh Postnatal Depression Scale. A range of covariates in mixed models was considered including age, education, number of children, family structure, physical health, past emotional problems and stressful life events. Key findings were as follows: (i) reported emotional and practical support from all three relationships declined over time in the cohort overall; (ii) reported emotional support from the husband, and emotional and practical support from the mother-in-law, declined more strongly in women with antenatal depressive symptoms; (iii) associations between depressive symptoms and worsening spouse relationship were more pronounced in traditional compared with nuclear families. Antenatal depressive symptoms predicted marked decline in the quality of key relationships over the postnatal period. This may account for some of the contemporaneous associations between depression and worse social support, and may compound the risk of perinatal depression in subsequent pregnancies.

  15. Spontaneous healing of spontaneous coronary artery dissection.

    PubMed

    Almafragi, Amar; Convens, Carl; Heuvel, Paul Van Den

    2010-01-01

    Spontaneous coronary artery dissection (SCAD) is a rare cause of acute coronary syndrome and sudden cardiac death. It should be suspected in every healthy young woman without cardiac risk factors, especially during the peripartum or postpartum periods. It is important to check for a history of drug abuse, collagen vascular disease or blunt trauma of the chest. Coronary angiography is essential for diagnosis and early management. We wonder whether thrombolysis might aggravate coronary dissection. All types of treatment (medical therapy, percutaneous intervention or surgery) improve the prognosis without affecting survival times if used appropriately according to the clinical stability and the angiographic features of the involved coronary arteries. Prompt recognition and targeted treatment improve outcomes. We report a case of SCAD in a young female free of traditional cardiovascular risk factors, who presented six hours after thrombolysis for ST elevation myocardial infarction. Coronary angiography showed a dissection of the left anterior descending and immediate branch. She had successful coronary artery bypass grafting, with complete healing of left anterior descending dissection.

  16. Spontaneous ileostomy closure

    PubMed Central

    Alyami, Mohammad S.; Lundberg, Peter W.; Cotte, Eddy G.; Glehen, Olivier J.

    2016-01-01

    Iatrogenic ileostomies are routinely placed during colorectal surgery for the diversion of intestinal contents to permit healing of the distal anastomosis prior to elective reversal. We present an interesting case of spontaneous closure of a diverting ileostomy without any adverse effects to the patient. A 65-year-old woman, positive for hereditary non-polyposis colorectal cancer type-I, with locally invasive cancer of the distal colon underwent en-bloc total colectomy, hysterectomy, and bilateral salpingoophorectomy with creation of a proximal loop ileostomy. The ostomy temporarily closed without reoperation at 10 weeks, after spontaneously reopening, it definitively closed, again without surgical intervention at 18 weeks following the original surgery. This rare phenomenon has occurred following variable colorectal pathology and is poorly understood, particularly in patients with aggressive disease and adjunct perioperative interventions. PMID:27279518

  17. Arachnoid cyst spontaneous rupture.

    PubMed

    Marques, Inês Brás; Vieira Barbosa, José

    2014-01-01

    Arachnoid cysts are benign congenital cerebrospinal fluid collections, usually asymptomatic and diagnosed incidentally in children or adolescents. They may become symptomatic after enlargement or complications, frequently presenting with symptoms of intracranial hypertension. We report an unusual case of progressive refractory headache in an adult patient due to an arachnoid cyst spontaneous rupture. Although clinical improvement occurred with conservative treatment, the subdural hygroma progressively enlarged and surgical treatment was ultimately needed. Spontaneous rupture is a very rare complication of arachnoid cysts. Accumulation of cerebrospinal fluid accumulation in the subdural space causes sustained intracranial hypertension that may be life-threatening and frequently requires surgical treatment. Patients with arachnoid cysts must be informed on their small vulnerability to cyst rupture and be aware that a sudden and severe headache, especially if starting after minor trauma or a Valsalva manoeuvre, always requires medical evaluation.

  18. Spontaneous Perforation of Pyometra

    PubMed Central

    Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-01-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perforation was performed. Although spontaneously perforated pyometra is rare, the condition must be borne in mind with regard to elderly women with acute abdominal pain. Preoperative diagnosis of perforated pyometra is absolutely essential. Computed tomography (CT) and MRI are diagnostic tools. In selected cases conservative approach at surgery can be opted. PMID:27152313

  19. Spontaneous Perforation of Pyometra.

    PubMed

    Sharma, Nalini; Singh, Ahanthem Santa; Bhaphiralyne, Wankhar

    2016-04-01

    Pyometra is collection of purulent material which occurs when there is interference with its normal drainage. It is an uncommon condition with incidence of 0.1 to 0.5% of all gynecological patients. Spontaneous rupture of uterus is an extremely rare complication of pyometra. A 65-year-old lady presented with pain abdomen and purulent vaginal discharge. Preoperative diagnosis of pyometra was made by magnetic resonance imaging (MRI). Laparotomy followed by peritoneal lavage and repair of perforation was performed. Although spontaneously perforated pyometra is rare, the condition must be borne in mind with regard to elderly women with acute abdominal pain. Preoperative diagnosis of perforated pyometra is absolutely essential. Computed tomography (CT) and MRI are diagnostic tools. In selected cases conservative approach at surgery can be opted.

  20. Spontaneous Rupture of Pyometra

    PubMed Central

    Mallah, Fatemeh; Eftekhar, Tahere; Naghavi-Behzad, Mohammad

    2013-01-01

    Spontaneous perforation is a very rare complication of pyometra. The clinical findings of perforated pyometra are similar to perforation of the gastrointestinal tract and other causes of acute abdomen. In most cases, a correct and definite diagnosis can be made only by laparotomy. We report two cases of diffuse peritonitis caused by spontaneous perforated pyometra. The first case is a 78-year-old woman with abdominal pain for which laparotomy was performed because of suspected incarcerated hernia. The second case is a 61-year-old woman with abdominal pain for which laparotomy was performed because of symptoms of peritonitis. At laparotomy of both cases, 1 liter of pus with the source of uterine was found in the abdominal cavity. The ruptured uterine is also detected. More investigations revealed no malignancy as the reason of the pyometra. PMID:24024054

  1. [Spontaneous pneumothorax in children].

    PubMed

    Michel, J L

    2000-03-01

    Spontaneous pneumothorax is rare in childhood. Before 12 years of age the main underlying pathologies are asthma, cystic malformations, post infectious bullae, and infectious pneumoniae. After 12 years of age it is mainly associated with cystic fibrosis and constitutional slim morphology. Symptoms vary according to the extent of lung collapse and the diagnosis is confirmed on chest X rays. In mildly symptomatic pneumothorax, spontaneous resolution is achieved within few days. When cardiorespiratory difficulties are present, mechanical evacuation of air from the pleural cavity is necessary through a tube drainage maintained until complete pulmonary reexpansion. Surgical treatment is indicated in case of persisting air leakage after one week of efficient drainage, large cystic malformation or post infectious bullae, recurring or bilateral pneumothorax.

  2. [Spontaneous spinal cord herniation].

    PubMed

    Rivas, J J; de la Lama, A; Gonza Lez, P; Ramos, A; Zurdo, M; Alday, R

    2004-10-01

    Spontaneous spinal cord herniation through a dural defect is an unusual condition. This entity has been probably underestimated before the introduction of MRI. We report a case of a 49-year-old man with a progressive Brown-Sequard syndrome. MRI and CT myelogram showed a ventrally displaced spinal cord at level T6-T7 and expansion of the posterior subarachnoid space. Through a laminectomy, a spinal cord herniation was identified and reduced. The anterior dural defect was repaired with a patch of lyophilized dura. The patient recovered muscle power but there was no improvement of the sensory disturbance. The diagnosis of spontaneous spinal cord herniation must be considered when progressive myelopathy occurs in middle-aged patients, without signs of spinal cord compression and typical radiological findings. Surgical treatment may halt the progressive deficits and even yield improvement in many cases.

  3. Spontaneous Iliopsoas Tendon Tear

    PubMed Central

    Rodriguez, Mary; Patnaik, Soumya; Wang, Peter

    2016-01-01

    Hip pain is one of the most common reasons for the elderly to present to the emergency department, and the differential diagnosis spectrum is vast. Iliopsoas injury is a relatively uncommon condition that may present with hip or groin pain. It is usually seen in athletes due to trauma, particularly flexion injuries. However, spontaneous iliopsoas tendon tear is extremely rare, and only a small number of cases have been reported; it has an estimated prevalence of 0.66% in individuals from 7 to 95 years. Risk factors include aging, use of steroids, and chronic diseases. Magnetic resonance imaging (MRI) using its high soft-tissue contrast resolution remains the most valuable imaging modality. A prompt diagnosis and treatment, which is usually conservative, is important to improve the quality of life in this group of patients. We describe a case of spontaneous iliopsoas tendon tear in an elderly woman. PMID:26929854

  4. Spontaneous Transomental Hernia

    PubMed Central

    Lee, Seung Hun

    2016-01-01

    A transomental hernia through the greater or lesser omentum is rare, accounting for approximately 4% of internal hernias. Transomental hernias are generally reported in patients aged over fifty. In such instances, acquired transomental hernias are usual, are commonly iatrogenic, and result from surgical interventions or from trauma or peritoneal inflammation. In rare cases, such as the one described in this study, internal hernias through the greater or lesser omentum occur spontaneously as the result of senile atrophy without history of surgery, trauma, or inflammation. A transomental hernia has a high postoperative mortality rate of 30%, and emergency diagnosis and treatment are critical. We report a case of a spontaneous transomental hernia of the small intestine causing intestinal obstruction. An internal hernia with strangulation of the small bowel in the lesser sac was suspected from the image study. After an emergency laparotomy, a transomental hernia was diagnosed. PMID:26962535

  5. Spontaneous recovery from acalculia.

    PubMed

    Basso, Anna; Caporali, Alessandra; Faglioni, Pietro

    2005-01-01

    A topic much considered in research on acalculia was its relationship with aphasia. Far less attention has been given to the natural course of acalculia. In this retrospective study, we examined the relationship between aphasia and acalculia in an unselected series of 98 left-brain-damaged patients and the spontaneous recovery from acalculia in 92 acalculic patients with follow-up. There was a significant association between aphasia and acalculia although 19 participants exhibited aphasia with no acalculia and six acalculia with no aphasia. We observed significant improvement between a first examination carried out between 1 and 5 months post-onset and a second examination carried out between 3 and 11 months later (mean: 5 months). The mechanisms of spontaneous recovery are discussed.

  6. Spontaneous nephrocutaneous fistula.

    PubMed

    Antunes, Alberto A; Calado, Adriano A; Falcão, Evandro

    2004-01-01

    Spontaneous renal fistula to the skin is rare. The majority of cases develop in patients with antecedents of previous renal surgery, renal trauma, renal tumors, and chronic urinary tract infection with abscess formation. We report the case of a 62-year old woman, who complained of urine leakage through the skin in the lumbar region for 2 years. She underwent a fistulography that revealed drainage of contrast agent to the collecting system and images suggesting renal lithiasis on this side. The patient underwent simple nephrectomy on this side and evolved without intercurrences in the post-operative period. Currently, the occurrence of spontaneous renal and perirenal abscesses is extremely rare, except in patients with diabetes, neoplasias and immunodepression in general.

  7. Spontaneous Pneumomediastinum in Labor

    PubMed Central

    Benlamkadem, Said; Labib, Smael; Harandou, Mustapha

    2017-01-01

    Spontaneous pneumomediastinum and subcutaneous emphysema also known as Hamman's syndrome is a very rare complication of labor that is often related to the valsalva maneuver during the labor. In most case, Hamman's syndrome is a self-limiting condition, rarely complicated unless there are underlying respiratory diseases. Chest X-ray can be a useful early diagnostic technique in severe clinical presentation. We report an uneventful pregnancy in a primigravid parturient, which was complicated in the late second stage of labor by the development of subcutaneous emphysema, pneumomediastinum, and mild pneumothorax. Spontaneous recovery occurred after four days of conservative management. This condition shows the major interest of labor analgesia especially locoregional techniques. PMID:28316849

  8. Spontaneous spinal epidural abscess.

    PubMed

    Ellanti, P; Morris, S

    2011-10-01

    Spinal epidural abscess is an uncommon entity, the frequency of which is increasing. They occur spontaneously or as a complication of intervention. The classical triad of fever, back pain and neurological symptoms are not always present. High index of suspicion is key to diagnosis. Any delay in diagnosis and treatment can have significant neurological consequences. We present the case of a previously well man with a one month history of back pain resulting from an epidural abscess.

  9. Spontaneous Symmetry Breaking

    NASA Astrophysics Data System (ADS)

    Strocchi, Franco

    One of the most powerful ideas of modern theoretical physics is the mechanism of spontaneous symmetry breaking. It is at the basis of most of the recent achievements in the description of phase transitions in Statistical Mechanics as well as of collective phenomena in solid state physics. It has also made possible the unification of weak, electromagnetic and strong interactions in elementary particle physics. Philosophically, the idea is very deep and subtle (this is probably why its exploitation is a rather recent achievement) and the popular accounts do not fully do justice to it.

  10. Spontaneous cerebrospinal fluid rhinorrhea.

    PubMed

    Yerkes, S A; Thompson, D H; Fisher, W S

    1992-07-01

    The diagnosis of CSF rhinorrhea requires the performance of a thorough history and physical examination. Often no objective findings can be found and further evaluation will be required. In our experience, metrizamide CT cisternography yields the most information for localization of the fistula. When indicated, patients can be protected against meningitis by using prophylactic antibiotics for 4-6 weeks to allow a fistula to close spontaneously. If the fistula fails to close during this time, surgical closure with dural or muscle graft with or without waxing of the bone is the treatment of choice.

  11. High-resolution inverse Raman and resonant-wave-mixing spectroscopy

    SciTech Connect

    Rahn, L.A.

    1993-12-01

    These research activities consist of high-resolution inverse Raman spectroscopy (IRS) and resonant wave-mixing spectroscopy to support the development of nonlinear-optical techniques for temperature and concentration measurements in combustion research. Objectives of this work include development of spectral models of important molecular species needed to perform coherent anti-Stokes Raman spectroscopy (CARS) measurements and the investigation of new nonlinear-optical processes as potential diagnostic techniques. Some of the techniques being investigated include frequency-degenerate and nearly frequency-degenerate resonant four-wave-mixing (DFWM and NDFWM), and resonant multi-wave mixing (RMWM).

  12. Order in Spontaneous Behavior

    PubMed Central

    Maye, Alexander; Hsieh, Chih-hao; Sugihara, George; Brembs, Björn

    2007-01-01

    Brains are usually described as input/output systems: they transform sensory input into motor output. However, the motor output of brains (behavior) is notoriously variable, even under identical sensory conditions. The question of whether this behavioral variability merely reflects residual deviations due to extrinsic random noise in such otherwise deterministic systems or an intrinsic, adaptive indeterminacy trait is central for the basic understanding of brain function. Instead of random noise, we find a fractal order (resembling Lévy flights) in the temporal structure of spontaneous flight maneuvers in tethered Drosophila fruit flies. Lévy-like probabilistic behavior patterns are evolutionarily conserved, suggesting a general neural mechanism underlying spontaneous behavior. Drosophila can produce these patterns endogenously, without any external cues. The fly's behavior is controlled by brain circuits which operate as a nonlinear system with unstable dynamics far from equilibrium. These findings suggest that both general models of brain function and autonomous agents ought to include biologically relevant nonlinear, endogenous behavior-initiating mechanisms if they strive to realistically simulate biological brains or out-compete other agents. PMID:17505542

  13. Spontaneous coronary artery dissection.

    PubMed

    Giacoppo, Daniele; Capodanno, Davide; Dangas, George; Tamburino, Corrado

    2014-07-15

    Spontaneous coronary artery dissection (SCAD) is a relatively rare and unexplored type of coronary disease. Although atherosclerosis, hormonal changes during pregnancy and connective tissue disorders might represent a sufficiently convincing explanation for some patients with SCAD, the many remaining cases display only a weak relationship with these causes. While on one side the clinical heterogeneity of SCAD masks a full understanding of their underlying pathophysiologic process, on the other side paucity of data and misleading presentations hamper the quick diagnosis and optimal management of this condition. A definite diagnosis of SCAD can be significantly facilitated by endovascular imaging techniques. In fact, intravascular ultrasound (IVUS) and optical coherence tomography (OCT) overcome the limitations of coronary angiography providing detailed endovascular morphologic information. In contrast, optimal treatment strategies for SCAD still represent a burning controversial question. Herein, we review the published data examining possible causes and investigating the best therapy for SCAD in different clinical scenarios.

  14. Spontaneous Ejaculations Associated with Aripiprazole

    PubMed Central

    EĞİLMEZ, Oğuzhan; ÇELİK, Mustafa; KALENDEROĞLU, Aysun

    2016-01-01

    Sexual side effects are common with antipsychotic use. Spontaneous ejaculations without sexual arousal have been previously described with several typical and atypical antipsychotics. We report the case of a man who had spontaneous ejaculations after stopping risperidone and starting 30 mg/day aripiprazole. Spontaneous ejaculations ceased 3 days after decreasing the aripiprazole dose to 15 mg/day. He denied sexual fantasies or increased sexual desire during the period in which he had spontaneous ejaculations. The partial agonistic effect of aripiprazole on D2 receptors may have augmented the mesolimbic dopaminergic pathway, which was suppressed by risperidone, causing spontaneous ejaculations in this patient. Serotoninergic effects of aripiprazole should also be considered. This unusual side effect should be questioned, particularly in patients who recieve aripiprazole after D2-blocking antipsychotics; otherwise, this side effect may cause embarrassement and noncompliance. PMID:28360773

  15. Spontaneous Intracerebral Hemorrhage: Management

    PubMed Central

    Kim, Jun Yup; Bae, Hee-Joon

    2017-01-01

    Spontaneous non-traumatic intracerebral hemorrhage (ICH) remains a significant cause of mortality and morbidity throughout the world. To improve the devastating course of ICH, various clinical trials for medical and surgical interventions have been conducted in the last 10 years. Recent large-scale clinical trials have reported that early intensive blood pressure reduction can be a safe and feasible strategy for ICH, and have suggested a safe target range for systolic blood pressure. While new medical therapies associated with warfarin and non-vitamin K antagonist oral anticoagulants have been developed to treat ICH, recent trials have not been able to demonstrate the overall beneficial effects of surgical intervention on mortality and functional outcomes. However, some patients with ICH may benefit from surgical management in specific clinical contexts and/or at specific times. Furthermore, clinical trials for minimally invasive surgical evacuation methods are ongoing and may provide positive evidence. Upon understanding the current guidelines for the management of ICH, clinicians can administer appropriate treatment and attempt to improve the clinical outcome of ICH. The purpose of this review is to help in the decision-making of the medical and surgical management of ICH. PMID:28178413

  16. Spontaneous breaking of supersymmetry

    SciTech Connect

    Zumino, B.

    1981-12-01

    There has been recently a revival of interest in supersymmetric gauge theories, stimulated by the hope that supersymmetry might help in clarifying some of the questions which remain unanswered in the so called Grand Unified Theories and in particular the gauge hierarchy problem. In a Grand Unified Theory one has two widely different mass scales: the unification mass M approx. = 10/sup 15/GeV at which the unification group (e.g. SU(5)) breaks down to SU(3) x SU(2) x U(1) and the mass ..mu.. approx. = 100 GeV at which SU(2) x U(1) is broken down to the U(1) of electromagnetism. There is at present no theoretical understanding of the extreme smallness of the ratio ..mu../M of these two numbers. This is the gauge hierarchy problem. This lecture attempts to review the various mechanisms for spontaneous supersymmetry breaking in gauge theories. Most of the discussions are concerned with the tree approximation, but what is presently known about radiative correction is also reviewed.

  17. Spontaneous baryogenesis without baryon isocurvature

    NASA Astrophysics Data System (ADS)

    De Simone, Andrea; Kobayashi, Takeshi

    2017-02-01

    We propose a new class of spontaneous baryogenesis models that does not produce baryon isocurvature perturbations. The baryon chemical potential in these models is independent of the field value of the baryon-generating scalar, hence the scalar field fluctuations are blocked from propagating into the baryon isocurvature. We demonstrate this mechanism in simple examples where spontaneous baryogenesis is driven by a non-canonical scalar field. The suppression of the baryon isocurvature allows spontaneous baryogenesis to be compatible even with high-scale inflation.

  18. Spontaneous emphysema of the neck.

    PubMed

    El-Ghazali, A M

    1983-04-01

    A case of spontaneous emphysema in the neck in a 17-year-old male was reported. Pathogenesis and management are discussed. Although it is a benign and self-limiting condition, it may carry a potential for serious complications.

  19. Spontaneous Activity in Crustacean Neurons

    PubMed Central

    Preston, James B.; Kennedy, Donald

    1962-01-01

    Single units which discharged with regular spontaneous rhythms without intentional stimulation were observed in the ventral nerve cord by intracellular recording close to the sixth abdominal ganglion. These units were divided into two groups: group A units in which interspike intervals varied less than 10 msec.; group B units in which interspike intervals varied within a range of 10 to 30 msec. Group A units maintained "constant" interspike intervals and could not be discharged by sensory inputs, while the majority of group B units could be discharged by appropriate sensory nerve stimulation. Both group A and B units discharged to direct stimulation when the stimulating and recording electrodes were placed in the same ganglionic intersegment, and directly evoked single spikes reset the spontaneous rhythm. In group B units, presynaptic volleys reset the spontaneous rhythm of some units; but in others, synaptically evoked spikes were interpolated within the spontaneous rhythm without resetting. The phenomenon of enhancement could also be demonstrated in spontaneously active units as a result of repetitive stimulation. It is concluded that endogenous pacemaker activity is responsible for much of the regular spontaneous firing observed in crayfish central neurons, and that interaction of evoked responses with such pacemaker sites can produce a variety of effects dependent upon the anatomical relationships between pacemaker and synaptic regions. PMID:14488667

  20. Spontaneous vortex nanodomain arrays at ferroelectric heterointerfaces.

    PubMed

    Nelson, Christopher T; Winchester, Benjamin; Zhang, Yi; Kim, Sung-Joo; Melville, Alexander; Adamo, Carolina; Folkman, Chad M; Baek, Seung-Hyub; Eom, Chang-Beom; Schlom, Darrell G; Chen, Long-Qing; Pan, Xiaoqing

    2011-02-09

    The polarization of the ferroelectric BiFeO(3) sub-jected to different electrical boundary conditions by heterointerfaces is imaged with atomic resolution using a spherical aberration-corrected transmission electron microscope. Unusual triangular-shaped nanodomains are seen, and their role in providing polarization closure is understood through phase-field simulations. Heterointerfaces are key to the performance of ferroelectric devices, and this first observation of spontaneous vortex nanodomain arrays at ferroelectric heterointerfaces reveals properties unlike the surrounding film including mixed Ising-Néel domain walls, which will affect switching behavior, and a drastic increase of in-plane polarization. The importance of magnetization closure has long been appreciated in multidomain ferromagnetic systems; imaging this analogous effect with atomic resolution at ferroelectric heterointerfaces provides the ability to see device-relevant interface issues. Extension of this technique to visualize domain dynamics is envisioned.

  1. Spontaneous closure of midline diastema following frenectomy.

    PubMed

    Koora, Kiran; Muthu, M S; Rathna, Prabhu V

    2007-03-01

    Maxillary midline diastema is a common aesthetic problem in mixed and early permanent dentitions. The space can occur either as a transient malocclusion or created by developmental, pathological or iatrogenical factors. Many innovative therapies varying from restorative procedures such as composite build-up to surgery (frenectomies) and orthodontics are available. Although literature says every frenectomy procedure should be preceded by orthodontic treatment, we opted for frenectomy technique without any orthodontic intervention. Presented herewith is a case report of a 9-year-old girl with a high frenal attachment that had caused spacing of the maxillary central incisors. A spontaneous closure of the midline diastema was noted within 2 months following frenectomy. The patient was followed up for 4 months after which the space remained closed and there was no necessity for an orthodontic treatment at a later stage.

  2. Thermodynamics and Spontaneity

    NASA Astrophysics Data System (ADS)

    Ochs, Raymond S.

    1996-10-01

    Despite the importance of thermodynamics as the foundation of chemistry, most students emerge from introductory courses with only a dim understanding of this subject. Generally students recognize that the information is significant, yet do not assimilate it into later studies, especially in applied fields such as biology and biochemistry. A clear sense of the problem is reflected in a number of other contributions to this Journal (e.g., 1 - 6). Most (1 - 4, 6) recommend increased rigor in derivation of equations. This may appeal to students in advanced courses in chemical thermodynamics, but not to most. A few other suggestions are to introduce the subject earlier in general chemistry courses (2) or to provide innovative ways to visualize reaction changes (3). I suggest that the problem lies at another level entirely: the meanings of the terms are not clear. Recently, MacNeal (7) introduced the concept of mathsemantics, the joining of mathematics with a deep understanding of the sense (semantics) in which it operates. For example, the author argues that not only can we add apples and oranges (yielding total fruit), but that anything less than such a synthesis is trivial. Mathematics is hard, not because of the actual mathematical part of the problem but because of the semantics. As discussed thoroughly by Weinburg (8), the very names we affix to ideas dominate how we think about them. A similar reorientation would benefit chemical education. By way of example, the word "spontaneous" is widely used in thermodynamics, presumably because the word is familiar and assists understanding of this subject. In the following, I will provide evidence that this word has contributed more to the obfuscation of chemical ideas than it has helped elucidate them. Literature Cited 1. Redlich, O. J. Chem. Educ. 1975, 52, 374 - 376. 2. Bergquist, W.; Heikkinen, H. J. Chem. Educ. 1990, 67, 1000 - 1003. 3. Macomber, R. S. J. Chem. Educ. 1994, 71, 311 - 312. 4. Sanchez, K. S.; Vergenz, R

  3. The Relationship among Spontaneity, Impulsivity, and Creativity

    ERIC Educational Resources Information Center

    Kipper, David A.; Green, Doreen J.; Prorak, Amanda

    2010-01-01

    The present study was designed to investigate two characteristics of spontaneity, its relationship to creativity and to impulsivity. We hypothesized a positive relationship between spontaneity and creativity, consistent with Moreno, 1953 "canon of spontaneity-creativity." We also predicted a negative relationship between spontaneity and…

  4. Spontaneous evaluative inferences and their relationship to spontaneous trait inferences.

    PubMed

    Schneid, Erica D; Carlston, Donal E; Skowronski, John J

    2015-05-01

    Three experiments are reported that explore affectively based spontaneous evaluative impressions (SEIs) of stimulus persons. Experiments 1 and 2 used modified versions of the savings in relearning paradigm (Carlston & Skowronski, 1994) to confirm the occurrence of SEIs, indicating that they are equivalent whether participants are instructed to form trait impressions, evaluative impressions, or neither. These experiments also show that SEIs occur independently of explicit recall for the trait implications of the stimuli. Experiment 3 provides a single dissociation test to distinguish SEIs from spontaneous trait inferences (STIs), showing that disrupting cognitive processing interferes with a trait-based prediction task that presumably reflects STIs, but not with an affectively based social approach task that presumably reflects SEIs. Implications of these findings for the potential independence of spontaneous trait and evaluative inferences, as well as limitations and important steps for future study are discussed. (c) 2015 APA, all rights reserved).

  5. Spontaneously Combustible Solids -- A Literature Search

    DTIC Science & Technology

    1975-05-01

    hydrides, carbides, and phosphides are incompatible with water because of thý- generation of flammable, toxic, and/or explosive products. Cesium , potassium...spontaneously flammable in moist air H Cesium Amide possible explosion on contact with water Cesium Antimony Alloy spontaneously flammable Cesium Arsenic Alloy...spontaneously flammable Cesium Bismuth spontaneously flammable Cesium , Metal spontaneously flammable in moist air at room temperature Cesitnu Oxide

  6. Code Mixing in a Young Bilingual Child.

    ERIC Educational Resources Information Center

    Anderson, Raquel; Brice, Alejandro

    1999-01-01

    Spontaneous speech samples of a bilingual Spanish-English speaking child were collected during a period of 17 months (ages 6-8). Data revealed percentages and rank ordering of syntactic elements switched in the longitudinal language samples obtained. Specific recommendations for using code mixing in therapy for speech-language pathologists are…

  7. Optical antenna enhanced spontaneous emission.

    PubMed

    Eggleston, Michael S; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C

    2015-02-10

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼ 200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ∼ 115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼ 2,500 × spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d(2). Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

  8. Optical antenna enhanced spontaneous emission

    PubMed Central

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; Yablonovitch, Eli; Wu, Ming C.

    2015-01-01

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ∼115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼2,500× spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = qω|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency. PMID:25624503

  9. Optical antenna enhanced spontaneous emission

    DOE PAGES

    Eggleston, Michael S.; Messer, Kevin; Zhang, Liming; ...

    2015-01-26

    Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ~200 THz optical frequency show a spontaneous emission intensity enhancement of 35 × corresponding to a spontaneous emission rate speedup ~115 ×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ~2,500 × spontaneous emission speedup at d ~10 nm, proportional to 1/d2. Unfortunately, at d spontaneous emission, where q|x(o)| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.« less

  10. Mixed Dementia

    MedlinePlus

    ... community Use our Virtual Library Treatment and outcomes back to top Because most people with mixed dementia are diagnosed with a single type of dementia, physicians often base their prescribing decisions on the type of dementia ...

  11. From mind wandering to involuntary retrieval: Age-related differences in spontaneous cognitive processes

    PubMed Central

    Maillet, David; Schacter, Daniel L.

    2015-01-01

    The majority of studies that have investigated the effects of healthy aging on cognition have focused on age-related differences in voluntary and deliberately engaged cognitive processes. Yet many forms of cognition occur spontaneously, without any deliberate attempt at engaging them. In this article we review studies that have assessed age-related differences in four such types of spontaneous thought processes: mind-wandering, involuntary autobiographical memory, intrusive thoughts, and spontaneous prospective memory retrieval. These studies suggest that older adults exhibit a reduction in frequency of both mind-wandering and involuntary autobiographical memory, whereas findings regarding intrusive thoughts have been more mixed. Additionally, there is some preliminary evidence that spontaneous prospective memory retrieval may be relatively preserved in aging. We consider the roles of age-related differences in cognitive resources, motivation, current concerns and emotional regulation in accounting for these findings. We also consider age-related differences in the neural correlates of spontaneous cognitive processes. PMID:26617263

  12. Density-driven spontaneous streak segregation patterns in a thin rotating drum.

    PubMed

    Liao, C C; Hsiau, S S; Nien, H C

    2014-06-01

    Granular mixtures may segregate because of external driving forces, which play an important role in industry and geophysics. We investigate experimentally the mechanism of density-driven spontaneous streak segregation patterns in a thin rotating drum. We find that a spontaneous streak segregation pattern can occur in such a system, which we call a D-system. A phase diagram identifies three segregation pattern regimes in this study: the mixing regime, the core segregation regime, and the streak segregation regime.

  13. Spontaneous emission and absorber theory

    NASA Astrophysics Data System (ADS)

    Pegg, David T.

    1997-01-01

    One of the long term interests of George Series was the construction of a theory of spontaneous emission which does not involve field quantisation. His approach was written in terms of atomic operators only and he drew a parallel with the Wheeler-Feynman absorber theory of radiation. By making a particular extra postulate, he was able to obtain the correct spontaneous emission rate and the Lamb shift reasonably simply and directly. An examination of his approach indicates that this postulate is physically reasonable and the need for it arises because quantisation in his theory occurs after the response of the absorber has been accounted for by means of the radiative reaction field. We review briefly an alternative absorber theory approach to spontaneous emission based on the direct action between the emitting atom and a quantised absorber, and outline some applications to more recent effects of interest in quantum optics.

  14. Spontaneous compactification and chiral fermions

    NASA Astrophysics Data System (ADS)

    Frampton, Paul H.; Yamamoto, Katsuji

    The question is addressed of which chiral fermions survive in spontaneously compactified solutions of the generalized Einstein-Yang-Mills field equations for higher even space-time dimensions. First, we study the allowed fermion representations of SU( N) which have no gauge or gravitational chiral anomalies in arbitrary even dimension and show how to find all such representations for the case of totally antisymmetric SU( N) tensors. Second, we look explicitly at monopole-induced spontaneous compactification in six dimensions; here, interesting chiral fermions in four dimensions do not occur easily but instead require highly artificial assignments of quantum numbers under the U(1) gauge group associated with the monopole. Finally, we consider instanton-induced spontaneous compactification in eight dimensions; for this case, we may readily obtain acceptable chiral fermions in four dimensions, including Georgi's three-family SU(11) model.

  15. Data mining in spontaneous reports.

    PubMed

    Bate, Andrew; Edwards, I R

    2006-03-01

    The increasing size of spontaneous report data sets and the increasing capability for screening such data due to increases in computational power has led to a recent increase in interest and use of data mining on such data. While data mining plays an important role in the analysis of spontaneous reports, there is general debate on how and when data mining should be best performed. While the cornerstone principles for data mining of spontaneous reports have been in place since the 1960s, several significant changes have occurred to make their use widespread. Superficially the Bayesian methods seem unnecessarily complex, particularly given the nature of the data, but in practice implementation in Bayesian framework gives clear benefits. There are difficulties evaluating the performance of the methods, but they work and save resources in managing large data sets. The use of neural networks allows more sophisticated pattern recognition to be performed.

  16. Spontaneous waves in muscle fibres

    NASA Astrophysics Data System (ADS)

    Günther, Stefan; Kruse, Karsten

    2007-11-01

    Mechanical oscillations are important for many cellular processes, e.g. the beating of cilia and flagella or the sensation of sound by hair cells. These dynamic states originate from spontaneous oscillations of molecular motors. A particularly clear example of such oscillations has been observed in muscle fibers under non-physiological conditions. In that case, motor oscillations lead to contraction waves along the fiber. By a macroscopic analysis of muscle fiber dynamics we find that the spontaneous waves involve non-hydrodynamic modes. A simple microscopic model of sarcomere dynamics highlights mechanical aspects of the motor dynamics and fits with the experimental observations.

  17. Spontaneous triplet, tubal ectopic gestation.

    PubMed Central

    Nwanodi, Oroma; Berry, Robert

    2006-01-01

    Only six cases of spontaneous, unilateral, triplet ectopic gestations have previously been reported. We now present a seventh case. The patient's prior obstetrical history was significant for a term stillbirth and a term cesarean section for breech. Quantitative betahCG was normal for gestational age; however, the increased trophoblastic mass of an inappropriately implanted multiple gestation may produce sufficient betahCG to mimic an intrauterine singleton gestation. Resolution was achieved via salpingostomy. This case is significant for being spontaneously conceived and not the result of assisted reproductive technologies. Furthermore, this case supports an association between prior cesarean section and ectopic gestation. Images Figure 1 PMID:16775922

  18. Flow Friction or Spontaneous Ignition?

    NASA Technical Reports Server (NTRS)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  19. Toddlers' Spontaneous Attention to Number

    ERIC Educational Resources Information Center

    Baroody, Arthur J.; Li, Xia; Lai, Meng-lung

    2008-01-01

    Hannula and Lehtinen (2001, 2005) defined spontaneous focusing on numerosity (SFON) as the tendency to notice the relatively abstract attribute of number despite the presence of other attributes. According to nativists, an innate concept of one to three directs young children's attention to these "intuitive numbers" in everyday situations--even…

  20. Spontaneous Number Representation in Mosquitofish

    ERIC Educational Resources Information Center

    Dadda, Marco; Piffer, Laura; Agrillo, Christian; Bisazza, Angelo

    2009-01-01

    While there is convincing evidence that preverbal human infants and non-human primates can spontaneously represent number, considerable debate surrounds the possibility that such capacity is also present in other animals. Fish show a remarkable ability to discriminate between different numbers of social companions. Previous work has demonstrated…