Brillouin-enhanced Four-wave Mixing Research Articles

Study on the asymptotic behavior of the interplay of stimulated Brillouin scattering and Brillouin-enhanced four-wave mixing in standard single-mode fibers

Study on the asymptotic behavior of the interplay of stimulated Brillouin scattering and Brillouin-enhanced four-wave mixing in standard single-mode fibers

Phase conjugate digital inline holography (PCDIH).

Digital inline holography (DIH) provides instantaneous three-dimensional (3D) measurements of diffracting objects; however, phase disturbances in the beam path can distort the imaging. In this Letter, a phase conjugate digital inline holography (PCDIH) configuration is proposed for removal of phase disturbances. Brillouin-enhanced four-wave mixing produces a phase conjugate signal that back propagates along the DIH beam path. The results demonstrate the removal of distortions caused by gas-phase shocks to recover 3D images of diffracting objects.

Polarization-decoupled four-wave mixing based on stimulated Brillouin scattering in a polarization-maintaining fiber

Polarization-decoupled four-wave mixing (FWM) based on stimulated Brillouin scattering (SBS) in a polarization-maintaining fiber is studied both theoretically and experimentally. We show the difference between Brillouin-enhanced FWM, which was studied a long time ago, and the Brillouin dynamic grating that was proposed in recent years. Under undepleted pump approximation, an analytical solution is given for the coupled equations, showing that a net phase-matching condition is dependent on pump power and frequency detuning from the Brillouin frequency. Experimental investigation of this net phase-matching condition provides a method to measure the spectral change in the refractive index that is responsible for the slow light effect based on SBS. Small refractive index changes (on the order of 10−8) versus frequency detuning can be determined experimentally.

Coexisting Brillouin, Rayleigh, and Raman-enhanced four-wave mixings

The coexisting Rayleigh and Brillouin attosecond sum-frequency polarization beats (ASPBs) and the coexisting Raman, Rayleigh, and Brillouin ASPBs have also been investigated via homodyne and heterodyne detections, respectively. The Raman, Rayleigh, and Brillouin-enhanced four-wave mixing processes strongly compete with each other in ASPBs. The heterodyne-detected signal of ASPBs offers the phase dispersion of the third-order nonlinear susceptibility in the homogeneous broadening material.

A composite phase conjugator based on Brillouin-enhanced four-wave mixing combining with stimulated Brillouin amplification – Erratum

A novel composite optical phase conjugator that combines Brillouin-enhanced four-wave mixing (BEFWM) and stimulated Brillouin amplification (SBA) in a compact structure is reported. A phase-conjugate wave seed is generated by BEFWM process with characteristics such as fast response, high conjugate fidelity and stability, then it is magnified by SBA with high energy-conversion efficiency. As a result, advantages of BEFWM and SBS can be realized at the same time. This composite conjugator has potentials for high-peak and high-average power laser applications, especially for short pulse or steep leading-edge pulse laser systems. Feasibility of this BEFWM-SBA mechanism is verified in theoretical simulations and demo experiments.

A composite phase conjugator based on Brillouin-enhanced four-wave mixing combining with stimulated Brillouin amplification

AbstractA novel composite optical phase conjugator that combines Brillouin-enhanced four-wave mixing (BEFWM) and stimulated Brillouin amplification (SBA) in a compact structure is reported. A phase-conjugate wave seed is generated by BEFWM process with characteristics such as fast response, high conjugate fidelity and stability, then it is magnified by SBA with high energy-conversion efficiency. As a result, advantages of BEFWM and SBS can be realized at the same time. This composite conjugator has potentials for high-peak and high-average power laser applications, especially for short pulse or steep leading-edge pulse laser systems. Feasibility of this BEFWM-SBA mechanism is verified in theoretical simulations and demo experiments.

Brillouin-enhanced nondegenerate four-wave mixing

We have observed Brillouin-enhanced nondegenerate four-wave mixing (NFWM) induced by an acoustic wave and Rayleigh-type NFWM induced by molecular reorientation in CS2. It was found that the acoustic wave and the molecular reorientation grating are not mutually independent. The existence of the acoustic wave destroys the phase coherence between the polarizations of the Rayleigh-type NFWM and the Brillouin-enhanced NFWM.

大信号布里渊增强四波混频相位共轭镜

大信号布里渊增强四波混频相位共轭镜

Theoretical study on temporal behavior of Brillouin-enhanced four-wave mixing

The nature of Brillouin-enhanced four-wave mixing (BEFWM) temporal modulating behavior is examined numerically. The evolution of the acoustic wave, which plays a key role in the process of energy inter-coupling, is simulated and analyzed. Based on this, the detailed mechanism of BEFWM temporal characteristics is explained. It is demonstrated that, modulations in the conjugate wave are related with the distribution and fluctuation of the acoustic wave, and influenced by parameters such as phonon lifetime, intensity of the signal and pump wave, effective interaction length, and so on.

The Use of Brillouin Enhanced Four Wave Mixing for Phase Conjugation of Laser Radiation.

Possibility of phase conjugation (PC) of solid-state laser radiation via Brillouin Enhanced Four-Wave Mixing (BEFWM) has been shown experimentally. Correction of various types of optical aberration introduced into incoming signal has been observed. PC-fidelity has been estimated to be equal to 0.62. Principle of operation of a multifunctional telescope system using BEFWM effect for correction for priary mirror aberration is briefly described.

Frequency structure in an electronically tuned Ti:sapphire laser:?periodic appearance of static fringes in both homodyne and heterodyne Michelson interferometers

Static interference fringes were observed repeatedly with changes of path difference in both homodyne and heterodyne Michelson interferometers. This unique coherence property of an electronically tuned Ti:sapphire laser with an intracavity acousto-optic tunable filter (AOTF) has revealed the frequency structure and dynamics of the laser field. The fact that static interference occurred in a heterodyne interferometer with unequal path lengths indicates backscattering of the intracavity laser field, suggesting that Brillouin-enhanced four-wave mixing occurs in the intracavity AOTF.

Temporal characteristics of polarization-decoupled, anti-Stokes-type Brillouin-enhanced four-wave mixing

The characteristics of time-dependent Brillouin-enhanced four-wave mixing (BEFWM) interaction were investigated. The temporal and spatial profiles of four optical waves and an acoustic wave in the BEFWM interaction of polarization-decoupled, anti-Stokes type were calculated using a relatively simple simulation method. In the simulation with step-function optical waves, two distinctive interaction regimes were observed: steady-state regime and reconversion regime which are distinguished by their characteristic temporal behaviors. The simulation with pump waves similar to the BEFWM experiment of polarization-decoupled, anti-Stokes scattering type showed that the temporal shape of the output signal well matched with the observed result.

Experimental investigation of high resolution imaging using Brillouin-enhanced four-wave mixing

Experimental investigation of high resolution imaging using Brillouin-enhanced four-wave mixing

Experimental investigation of high resolution imaging using Brillouin-enhanced four-wave mixing

We present the results of an experimental investigation of a polarization-decoupled Brillouin-enhanced four-wave mixing (BEFWM) configuration used for short-pulse high-resolution imaging. In this geometry, the four-wave mixing medium is carbon disulphide (CS2) and the counterpropagating pump is generated from the forward pump by stimulated Brillouin scattering in a second CS2 cell. This configuration produced a good quality, high resolution (∼9 μm) phase conjugate image of a United States Air Force test chart, correcting for aberrations in the system.

Brillouin-enhanced four-wave-mixing vector phase-conjugate mirror with beam-combining capability

It is often desirable to remove both wave front and polarization aberrations from an optical beam. Scalar phase conjugation, such as ordinary stimulated Brillouin scattering, can correct only for wave-front aberrations. We have developed a new geometry for Brillouin-enhanced four-wave mixing that performs vector phase conjugation to correct for both wave-front and polarization distortions. Results show a reduction in the depolarization losses from 50% to less than 2% of the total output energy. Coherent, variable, multiple-beam combination is achieved without need of nonreciprocal devices such as Faraday rotators.

The Four-Wave Mixing and the Hydrodynamic Excitations in Smectic A Liquid Crystals

Abstract A nondegenerate four-wave mixing (FWM) on a new type of Kerr nonlinearity determined by the layer deformations in smectic A liquid crystal (SmA) is considered. It is shown that in the case when the frequency difference of the coupled electromagnetic waves (EMW) is close to the frequency of the second sound (SS), a strong parametric coupling among EMW through the dynamic grating of layer deformations occurs. As a result EMW with the lowest frequency is amplified and EMW with the highest frequency is depleted, while the two EMW with the intermediate frequencies are compressed in space and their envelopes take the form of a spatial soliton. The explicit expressions of all amplitudes are calculated. The gain coefficient appears to be one order of magnitude greater than the one for stimulated scattering on an ordinary sound in organic liquids. The interaction of EMW with the specially selected frequencies and wave vectors gives rise to the analog of Brillouin enhanced FWM (BEFWM) resulting in the ampl...

Optimization of the field of view of a Brillouin-enhanced four-wave-mixing phase conjugator

A Brillouin-enhanced four-wave mixing phase conjugator featuring a field of view that varies by approximately an order of magnitude, i.e., from 2 to 20 mrad, is described. We control this variable field of view by utilizing a slightly noncollinear pumping geometry and by adjusting the pump-pump frequency difference to optimize the phase mismatch for the overall process. A model that describes the interplay between frequency and geometry to the Brillouin-enhanced four-wave-mixing phase mismatch is found to predict the expandable field of view.

Correction of phase and depolarization distortions in a multimode fiber at 1064 μm with stimulated-Brillouin-scattering phase conjugation

We have used phase conjugation to compensate phase distortions and depolarization introduced in multimode fibers having 2-m lengths and 400-microm core diameters. The experiment was performed at a wavelength of 1.064 microm, and we achieved phase conjugation using Brillouin-enhanced four-wave mixing in a 0.8-mm-core hollow quartz lightguide filled with TiCl(4). The far-field conjugation fidelity was 70%, and the residual depolarization was <1%. Comparable compensation was achieved by use of either a graded-index or a step-index fiber.

Demonstration of the spectral and the geometrical criteria that control high-reflectivity Brillouin-enhanced four-wave mixing

The interplay between frequency and geometry in high-reflectivity Brillouin-enhanced four-wave mixing (BEFWM) is examined. We obtain detailed knowledge of the frequency relationship among all four interacting beams by using a unique laser system that directly supplies all three BEFWM input beams with independent and precise relative frequency control and by analyzing the phase-conjugate output spectrum. In accordance with an existing model, geometry measurements clearly confirm an inverse relationship between pump–pump and pump–signal angles when the input frequencies are fixed, and the total phase mismatch is found to be constant over a broad range of spectrally and spatially diverse BEFWM conformations. Output detunings similar to previously reported input detunings are observed. Line-shape analysis of the various resonances supports the concept that high-reflectivity BEFWM arises from the formation of distinct read and write gratings and that the energy transfer between them is controlled by a relatively broad phase-mismatch range.

A frequency-upshifting Brillouin enhanced four-wave mixing scheme using an iodine laser as a pump source

The characteristics of temporal modulation and frequency recovery in frequency-upshifting Brillouin-enhanced four-wave mixing (BEFWM) using CS 2 as a nonlinear medium were investigated experimentally for an iodine laser. BEFWM interaction in a stimulated Brillouin scattering (SBS) generator-amplifier scheme was tested, first, and compared with a new BEFWM scheme in which the amplifier cell is placed out of the beam path of the SBS signal originating from the generator cell, allowing a more efficient and more strongly compressed pulse. The output signal from BEFWM recovers the original laser frequency by frequency-upshifting a Stokes-shifted probe. A pulse compression from 50 ns to 3 ns between the incident laser pulse and the output signal and a power conversion efficiency of 30% with respect to the Stokes-shifted pump were obtained through BEFWM.