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Based on the four-wave mixing mechanism and light fanning effect, a mutually pumped phase conjugator(MPPC) model is proposed to analyze the variation of MPPC output response with time for different scattering seed value. It shows that preset grating can enhance the fan light intensity when it satisfies Bragg condition and also can shorten MPPC response time. In experiment the bird-wings MPPC is done with or without the preset grating and the variation of MPPC reflectivity with time is obtained in two cases, and simulation conclusion is in agreement with the experimental result. These results have importance for applications of MPPC on optical heterodyne detection.

Terahertz radiation has been studied extensively both experimentally and theoretically within the past decades. A number of methods have been developed to generate terahertz radiation using ultra-short laser pulses, including photoconductive effect, optical rectification, and so on. The photoconductive effect has been utilized to generate THz radiation from a piece of semiconductor with antenna structure. The bias electric field between the electrodes of photoconductor is limited by the breakdown field of the semiconductor. In order to enhance the THz radiation power, the distribution of electric field on the surface of the substrate is simulated and the relationship between the geometrical structure of antenna and bias electric field is analyzed. The results show that the bow-tie antenna works more safely than other antennas under the same condition, and the breakdown risk of the PC antenna is reduced and the capability of resistance to voltage is improved.

The photorefractive adaptive optical heterodyne detection system (PAOHDS) is proposed. The dynamic properties of mutually pumped phase conjugate (MPPC), the key technology to the PAOHDS, are studied theoretically. The three-dimensional distribution of MPPC refraction index grating in time and length axis is simulated numerically. The dependence of dynamic properties of MPPC on the intensity of the fanning light is presented.The stronger the intensity of the fanning light is, the less response time for MPPC is. The dependence of dynamic properties of MPPC on the coupling strength is presented. The greater the coupling strength is, the less response time for MPPC is. These results provide theoretical basis to reduce response time of PAOHDS.

The phase conjugation properties of self-pumped phase conjugation (SPPC), mutually pumped phase conjugation (MPPC), SPPC and MPPC coexisting are researched in Cu:KNSBN crystal with Q-switched single longitudinal mode YAG pulse laser pumping. The dependence of the reflectivity of phase conjugation on the incidence position and angle are obtained experimentally. The results show the optimal incident parameter exists in photorefractive phase conjugation effect.

The theoretical model of a photorefractive optical switch, which is implemented by adjusting the wavelength and space-phase of the read-out beam to control the diffraction direction of volume grating in a photorefractive crystal, is proposed. For N channel optical switch, each channel include n dissimilar wavelength carrying information with distinct space-phase, and any wavelength can turn into any other N -1 channel controlled by space-phase. In order to obtain this device, multiple holograms be recorded in a photorefractive crystal, performing an optical database accessible either by wavelength or by space-phase multiplexing. The holograms were written in a Fe doped LiNbO 3 using an Ar + laser with its three wavelength. The diffraction direction depended on wavelength and space-phase of the read-out beam, which agrees with the theoretical prediction and indicates that photorefractive crystal possesses excellent optical switching properties. It is demonstrated that the diffraction direction of the volume grating is relevant to the wavelength and space-phase of read-out beam; this property can be used to implement the all-optical switch.

Optical waveguide array are attractive for high-speed, wide-angle optical beam steering or deflection, but optical waveguide arrays radiate undesirable sidelobes. It is shown that suppression of sidelobes can be accomplished by configuring array elements in nonuniform pattern. Tow kinds of arrangement of linear changed spaced optical waveguide array are discussed. Sidelobes can be suppressed deeply. Especially, the light path area ratio can be improved to 71.9% by using symmetrical structure array. Steering characteristic shown that the maximum steering degree of 24 0 (-3dB) can be obtained by nonuniform spaced optical waveguide array. Keywords: optical waveguide array, sidelobes suppression, nonuniform pattern, symmetrical structure 1. INTRODUCTION Optical beam steering is one of the most important functions in the field of optoelectronics. Thus far, optical beam steering devices have found a number of very useful applications. Such a technology may offer rapidly optical radar, with many other applications to displays, optical switching, and optical router

Based on the programmable phase modulation technique with a multi-channel optical wave-guide array, a novel method used for collimated laser precision scanning was presented. Optical system and control circuit have been designed for the multi-channel optical wave-guide array. Theoretical analysis and experimental result shows that the method can be used for small angle adjusting and big angle scanning of collimated laser in free space light communication.

In steady state and two dimensions the distributions of the nonlinear refractive index in a photorefective crystals under the conditions of supporting low intensity spatial solitons are studied. It is shown that steady state spatial bright solitons of modulated ThM00 mode Gaussian waveform can form and induce planar array waveguides in photorefractive crystal. The effects of modulating conditions, the intensity of spatial solitons and the external bias electric field on profile of refractive index of the array waveguides is investigated.