Feedback method of the noise suppression in wave-mixing amplifiers based on non-linear materials with photorefractive response in a reflection grating configuration

In the photorefractive wave-mixing system, fluctuation in the signal beam intensity of the photorefractive output with a reflection grating has been analyzed by employing pump feedback method. In this method, fluctuations of the photorefractive wave-mixing process not only induce the intensity fluctuation of the mixing waves but also induce phase fluctuation of the mixing waves. Thus, the phase of the pump and signal beams at the output surface fluctuates in time around a mean value. Using such a positive feedback method of a pump beams, the relative fluctuation in the photorefractive output signal beam intensity with respect to its mean intensity can be minimized significantly without reducing its mean intensity. The factors that control the fluctuation in the signal beam intensity, such as the phase fluctuation of the output pump beam, absorption strength of the material and the feedback reflectivity of the cavity mirrors, on the relative fluctuation of the output signal intensity in the photorefractive wave-mixing systems have been studied in detail. It has been found that the fluctuation of the output signal intensity relative to its mean intensity in the photorefractive wave-mixing system can be suppressed to larger extent by taking lower value of feedback reflectivity of the cavity mirrors which could exist at a higher value of absorption strength of the photorefractive materials.     

NONLINEAR EFFECTS OF THIRD-AND FIFTH-ORDER ON POLARIZATION BEATS IN A FOUR-LEVEL SYSTEM

We have employed second-order coherence function theory to study the nonlinear effects of third-and fifth-order on polarization beats in a four-level system (TPBFS and FPBFS). It is found that the different temporal behavior of the beat signal in TPBFS and FPBFS depends on the stochastic properties of the lasers and transverse relaxation rate of the transition. We have considered the cases that pump beams have either narrow band or broadband linewidth and found that for both cases a Doppler-free precision can be achieved in the measurement of the energy-level difference between two excited states which are dipolar forbidden from the ground state. We also discussed the spatiall modulation behavior of the beat signal.     

Properties of optical fiber based synchronous heralded single photon sources at 1.5 μm

1.5 μm synchronous heralded single photon source (HSPS) is experimentally demonstrated based on spontaneously four wave-mixing in liquid nitrogen cooled dispersion shifted fiber. Experimental results show that both preparation efficiency and conditional second order correlation function g(2)(0) increase with pump light level. Between the two important parameters, tradeoff should be taken to obtain high quality fiber based synchronous HSPS. A HSPS with preparation efficiency of >60% and g(2)(0)<0.06 is achieved, multi-photon probability of which is reduced by a factor of >16 compared with the Poissonian light sources. Experimental results show a great potential of the fiber based synchronous HSPS for quantum information applications.     

布里渊增强四波混频技术及其应用

探讨一种基于非线性光学相位共轭特性的布里渊增强四波混频技术,由于具有对微弱信号无延迟、高增益的反射特性,布里渊增强四波混频技术在激光探测方面具有良好应用前景．     

V型三能级系统中极化拍频的不对称特性

在抽运光为窄带或宽带的情形下 ,对 V型三能级系统中极化拍频的不对称特性进行了研究 ,发现这种不对称特性是由于光学元件色散所导致的零延时的漂移引起的     

Synthesis of Poly[（3-octanoylpyrrole-2,5-diyl）-p-nitrobenzylidene] and Its Third-order Nonlinear Optical Property

Introduction Nonlinearoptical(NLO)organicpolymers havereceivedincreasingattentionbecauseoftheir excellentbehaviorandgoodprospectsforapplica- tiontohightechnologiessuchasopticalcommuni- cation,highdensityopticalstorageandall-optical informationprocess[1_4].Thepoly[heteroarylene- methines]andtheirderivativesareregardedaspo- tentiallyapplicativeNLOmaterials[5_8],buttheir solubilityandfilm-formingperformancearenot goodwhichisabottleneckproblemfortheapplica- tionofthesepolymers.Inthisstudy,anovel…