一种基于PDLC-KIO_3的新型光倍频开关设计与实现

Design and experiment of a novel optical switch for second harmonic generation based on PDLC and KIO_3

利用聚合物分散液晶(PDLC)的开关特性与KIO3微晶体的非线性光学特性,研制出具有倍频效应(SHG)并且倍频光强电控可调谐的光变频开关。将YAG激光脉冲入射到开关器件,通过调制施加在开关上的驱动电压,当光开关闭合时,可阻挡基频光脉冲,抑制SHG,当光开关开启时,可在散射光路中观察到显著的SHG,开、关态倍频光强对比度可达6∶1。实验发现,驱动电压在0～80 V间,倍频光强能够实现近似线性的调制。测试表明,该变频开关的响应时间为20 ms。

A novel optical switch for second harmonic generation（SHG） is presented based on the electrooptical switching effect of polymer dispersed liquid crystal（PDLC） and nonlinear optical characteristics of KIO3 powder. YAG laser pulse enters the SHG optical switch,at the same time,an ac electric field is applied on PDLC for modulation. When the switch is in off-state,the second harmonic light is restrained. When the switch is in on-state, the second harmonic waves of YAG laser are generated and detected in the scattered direction. The intensity contrast ratio of second harmonic waves is 6 ： 1 between ＂on＂ and ＂off＂ state. Experimental results demonstrate that the intensity of SHG could be modulated linearly by the switch when ac electric potential is changed from 0 to 80 V. The response time of the switch is 20 ms.