共振简并四波混频光学相位共轭的研究

本文考虑了非线性极化强度对cos(k·r)的依赖关系,对共振增强简并四波混频的半经典处理提出了修正,得到相位共轭反射率满足的Riccatti方程.使用可调谐连续波CO_2激光器和SF_6气体作非线性介质作了实验研究.获得了(0.2～0.8)×10~(-4)的反射率.     

Optical phase conjugation by degenerate four-wave mixing in basic green 1 dye-doped gelatin film using He–Ne laser

Optical phase conjugation in gelatin film doped with basic green 1 has been measured using CW laser radiation (λ=632.8 nm) generated by He–Ne laser of total power 35 mW. The degenerate four-wave mixing (DFWM) experiment allowed for measurement of phase conjugate reflectivity as a function of dye concentration, backward beam intensity, forward beam intensity, probe beam intensity, mean pumping beam intensity and angle between the forward pumping beam and probe beam. For 1 mM concentration of basic green 1-doped gelatin film, 0.1% phase conjugate reflectivity has been observed.     

Nd:YAG激光在单晶硅中的四波混频相位共轭

以单晶硅作非线性介质,用调Q脉冲Nd:YAG激光作四渡混频,获得了相位共轭反射光波.从光激发电子-空穴对浓度及其所产生的相位光栅出发,理论计算了相位共轭镜的反射率.实验获得的共轭镜反射率为125%,并与实验中显示了其对相位干扰的补偿特性.     

Study of non-linear optical phase conjugation in Ca by resonant degenerate four-wave mixing via bound excited states

. The dependence of the reflectivity on the vapour density, the buffer gas pressure and the pump beams intensity was investigated. The influence of the strong linear absorption was taken into account in a theoretical model that led to a satisfactory interpretation of the experimental results. A maximum reflectivity of 46% was measured under optimized conditions. The effect was also studied through the high-lying bound states . The maximum measured reflectivity was as high as for the first excited state. The effect of the oscillator strength on the reflectivity was demonstrated experimentally and interpreted with the help of a simple theoretical model. Received: 11 June 1996     

Contribution of resonance medium amplitude and phase modulation to the effectiveness of phase conjugation by degenerate four-wave mixing

The contribution of amplitude and phase modulation to the energetic efficiency of wavefront conjugation (WFC) under degenerate four-wave mixing is studied in resonant media simulated by a two- or a three-level scheme. It is shown that a WFC-mirror of reflectivityR higher than unity may be achieved only in the presence of the medium phase modulation. Optimum conditions for obtaining high-efficiency (R>1) WFC are defined.     

A tunable narrowband optical filter via phase conjugation by nondegenerate four-wave mixing in a doppler-broadened resonant medium

The formulation of phase conjugation via nondegenerate four-wave mixing in a Doppler-broadened resonant medium is generalized to include nondegenerate pump frequencies. This process is shown capable of yielding a tunable optical band-pass filter whose central frequency can be tuned over the entire Doppler profile with only a small degradation of the filter efficiency while still maintaining a bandwidth limited by the homogeneous linewidth.     

Optical bistability and hysteresis in phase conjugation by degenerate six-photon mixing

First observation of non-cavity optical bistability and hysteresis in the phase conjugation by degenerate six-photon mixing in CdS crystals together with some analytical consideration is reported.     

Tunable phase conjugation by intracavity degenerate four-wave mixing in an injection-seeded solid dye laser

We demonstrate efficient degenerate four-wave mixing in a laser injection-seeded solid dye laser. Phase-conjugate energy of as much as 140 times the total energy injected externally into the phase conjugator was extracted. Moreover, efficient phase-conjugate energy was obtained in the broad wavelength region from 558 to 567 nm.     

Dynamic holograms and phase conjugation in multilevel resonant media

The generation of dynamic holograms and four-wave phase conjugation in resonant media has been investigated under conditions of interaction between radiation and excited singlet and triplet states. Two mechanisms of optical control of resonant media non-linearities using independent pump-up to increase the diffraction efficiency of dynamic holograms have been considered. The peculiarities of non-linear recording of holograms, and a variant of quadratic recording, have been investigated. The dependence of the efficiency of diffraction by dynamic holograms on the intensity of interacting waves and the spectroscopic characteristics of the medium has been analysed.     

Optical chaos in multiple degenerate four-wave mixing

Spatial evolution has been studied of an ensemble of equal-frequency light waves involved in several four-wave mixing processes under linear photoabsorption. It is shown that this system may exhibit spatial chaos caused by competition of optical mixing processes with strong energy exchange between the waves. For pulsed radiation, the temporal envelopes of interacting waves undergo modulations which may also be of chaotic character. Also discussed are possible variants of identifying chaos in systems of interacting light waves experimentally and the role of accompanying photoprocesses (photoabsorption, self-action of radiation).     

The feasibility of C. W. degenerate four-wave mixing in the far-infrared to millimeter region using an artificial Kerr medium

Using the results of Rogovin, the C. W. submillimeter phase conjugate reflectivities and response times of various prototype suspensions have been calculated for the degenerate four-wave mixing geometry. Assuming realistic liquid and particle optical constants as well as realistic submillimeter laser pump powers it is demonstrated that phase conjugate reflectivities approaching or exceeding unity could be expected in the strong pump limit for a wavelength of 100 microns. For longer wavelengths phase conjugation is not practical because the grating formation time exceeds the particle fall time hence no spatial grating can be formed. However, it is shown that if the particle buoyancy could be increased, phase conjugation could proceed with high efficiency at longer wavelengths.     

150-times phase conjugation by degenerate four-wave mixing in a continuous-wave Nd:YVO4 amplifier

The high phase-conjugate reflectivity of 150, by four-wave mixing in a diode-pumped Nd:YVO₄, has been demonstrated. The phase-conjugate mirror was capable of correcting the phase aberration of a probe beam. The experimental diffraction efficiency of the transmission gratings was 60. Received: 8 April 2002 / Revised version: 10 June 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +81/43-290-3490, E-mail: omatsu@image.tp.chiba-u.ac.jp     

Phase conjugation in fluorescein film by degenerate four-wave mixing and holographic process

Phase conjugation is performed in a fluorescein film by a cw Ar ion laser of the wavelength 0.488 μm in a degenerate four-wave mixing (DFWM) configuration. It becomes apparent that the phase conjugate wave is generated simultaneously by not only DFWM but also a holographic process and that the DFWM and holographic components of the phase conjugate wave have different time constants.     

Optical phase conjugation in the hybrid polymer liquid crystal panel

In this paper, we present experimental results of the optical phase conjugation (PC) process in nematic liquid crystal cell with a photoconducting polymer layer (PVK doped with TNF). We analyze and discuss the influence of a few parameters (applied voltage, power of the laser beams, and geometry of an experiment) on conjugation efficiency. We also present experimental results showing possible application of the optical phase conjugation phenomenon in correction of phase distortion and aberration.     

Real-time non-destructive testing of phase objects using four-wave mixing with photorefractive BGO crystals

Real-time non-destructive testing of phase and transparent objects using degenerate four-wave mixing with photorefractive BGO crystals is described. Some quantitative results of thickness variations of phase objects such as a thin optical wedge and a thin BGO crystal are also given.     

近简并四波混频相位共轭介质中的光强分布

从求解耦合波方程出发，详细研究了非线性光学介质中由近简并四波混频所产生的相位共轭过程。以上述波方程的解为基础，给出作为混频结果的反射传播相位共轭波沿介质轴向的光强分布，得到比以往文献中所报道的更为精确的结果，从而为选择工作物质的最佳尺寸提供了理论依据。     

简并四波混频相位共轭介质中的光强分布

相位共轭现象在很多领域有着广阔的应用前景。本文对非线性介质中所发生的简并四波混频相位共轭过程进行了较详细的分析，以耦合波动方程的解为基础，研究了介质中正向探测波和反向相位共轭波的光强分布，得到比迄今文献报导的更为确切的结果。     

向列相液晶中光学相位共轭技术的研究进展

对向列相液晶中光学相位共轭技术的研究进展进行了介绍,分析总结了向列相液晶中光学相位共轭过程的机理与实验方法,并对向列相液晶中的光学相位共轭技术的应用前景进行了展望。     

Intracavity resonant degenerate 4-wave mixing in atomic sodium vapor: Bistability in phase conjugation

We report on intracavity phase conjugation via resonant degenerate 4-wave mixing in atomic sodium vapor with the use of transverse optical Zeeman pumping as a versatile nonlinear mechanism. Under appropriate conditions the phase conjugate wave is found to display bistability, polarization switching and magnetically-induced selfoscillations. Our measurements are shown to be in fair agreement with theoretical predictions based on a simple analytic treatment for a homogeneously broadened coupled 4-level system.