记录方式对光致聚合物中全息光栅形成过程的影响

根据光致聚合物记录机理,研究了不同记录方式对光栅衍射效率的影响.对已有的光致聚合物光栅形成的一阶扩散模型进行简化,求解出全息曝光、暗增长、均匀后曝光过程对应的折射率调制度的解析式.应用所得解析结果,对三种记录方式在不同光强下的折射率调制度动态进行数值模拟.采用蓝敏光致聚合物,分别在4 mW/cm~2和2 mW/cm~2光强下应用不同方式记录光栅,结果表明:如果曝光光强较高,暗增长的记录方式将获得相对高的饱和折射率调制度,而均匀后曝光会加速达到饱和的进程.

The Effects of Recording Modes to the Formation of Holographic Grating in Photopolymer

Based on the recording mechanism of photopolymer,the effect of different recording modes on the diffraction efficiency of gratings was investigated.The existing first-harmonic diffusion model of grating formation in photopolymer was simplified,then the analytic expressions of refractive index modulation for holographic exposure,dark enhancement and uniform post-exposure were educed.The kinetics of refractive index modulation for these three recording modes under different exposure intensities were numerically simulated by using the analytic expressions.Experiments were done in a new blue-sensitized photopolymer material.The gratings were recorded by different recording modes with exposure intensities of 4 mW/cm~2 and 2 mW/cm~2 respectively.The results showed that if the intensity was high,the dark enhancement mode yielded to a high saturated refractive index modulation,while uniform post-exposure made the course of saturation fast.