丝状液晶非线性光学衍射效应的弛豫时间研究

On the Relaxation Time of Nonlinear Optical Diffraction Effect in Nematic Liquid Crystals

本文研究了丝状液晶在光感应下产生衍射光束的弛豫时间,找出了与分子重新取向的响应时间相联系的对应关系,对影响弛豫时间的三种重要因素作了理论分析。对MBBA的弛豫时间测量结果与理论计算结果一致。

Based on the basic mechanism of nematic liquid crystal of causing a nonlinear optical effect, the photo-Kerf effect, the relaxation of molecular reorientation in MBBA liquid crystal under the action of light field is discussed. It is the first time that the interference brought about by two mutually coherent laser beams on the membrane of the liquid crystal has been treated theoretically. A phase grating constant is introduced and the formula for the relaxation time molecular reorientation is derived. Factors affecting the relaxation time are analyzed. The relationship between the relaxation time of diffracted beam and that of molecular reorientation has been found. The relaxation of diffracted beam was observed by experiment. With the computer-based signal and data processing technique, the relaxation times of diffracted beam under different conditions have been measured and experimental results for MBBA are found to be in fairly good agreement with theoretical ones.