Lin Hui-Chi, Chu Chia-Wei, Li Ming-Shian, Fuh Andy Ying-Guey
Department of Electro-Optical Engineering, National Formosa University, Yunlin, Taiwan.
Opt Express. 2011 Jul 4;19(14):13118-25. doi: 10.1364/OE.19.013118.
The reorientation inversion of liquid crystal molecules in azo-dye-doped liquid crystal (ADDLC) films irradiated by biphotonic (green and red light) lasers is studied using the self-phase-modulation method. The results show that the induced change of refractive index (∆n) in an ADDLC cell illuminated with a fixed intensity of green light increases with the red-light intensity. Notably, the value of ∆n is initially negative, and becomes positive when the intensity of the red laser is increasing. It is due to the fact that an extra positive torque is exerted on the LCs, which is produced by cis-isomers upon absorbing red light to compensate the negative torque induced by the excitation of the green light.
利用自相位调制方法研究了双光子（绿光和红光）激光辐照下偶氮染料掺杂液晶（ADDLC）薄膜中液晶分子的重新取向反转。结果表明，在固定强度绿光照射下的ADDLC盒中，诱导折射率变化（∆n）随红光强度增加而增大。值得注意的是，∆n的值最初为负，当红色激光强度增加时变为正。这是因为在液晶上施加了额外的正扭矩，该扭矩由顺式异构体吸收红光产生，以补偿绿光激发所诱导的负扭矩。
