基于具有纳米尺寸液滴的染料掺杂聚合物分散液晶的全光可控随机激光器。

All-optically controllable random laser based on a dye-doped polymer-dispersed liquid crystal with nano-sized droplets.

作者信息

Lee C-R, Lin S-H, Guo C-H, Chang S-H, Mo T-S, Chu S-C

机构信息

Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan 701, Republic of China.

出版信息

Opt Express. 2010 Feb 1;18(3):2406-12. doi: 10.1364/OE.18.002406.

DOI:10.1364/OE.18.002406

PMID:20174070

Abstract

This study elucidates for the first time an all-optically controllable random laser in a dye-doped polymer-dispersed liquid crystal (DDPDLC) with nano-sized LC droplets. Experimental results demonstrate that the lasing intensity of the random laser can be controlled to decrease by increasing irradiation time/intensity of one green beam, and increase by increasing the irradiation time of one red beam. The all-optical controllability of the random laser is attributed to the green (red)-beaminduced isothermal nematic-->isotropic (isotropic-->nematic) phase transition in LC droplets by trans-->cis (cis-->trans back) isomerization of azo dyes. This isomerization may decrease (increase) the difference between the refractive indices of the LC droplets and the polymer, thereby increasing (decreasing) the diffusion constant (or transport mean free path), subsequently decreasing the scattering strength and, thus, random lasing intensity.

摘要

本研究首次阐明了一种在具有纳米尺寸液晶微滴的染料掺杂聚合物分散液晶（DDPDLC）中的全光可控随机激光器。实验结果表明，通过增加一束绿色光束的照射时间/强度，随机激光器的激光强度可被控制降低，而通过增加一束红色光束的照射时间，激光强度则会增加。随机激光器的全光可控性归因于偶氮染料通过反式→顺式（顺式→反式回变）异构化在液晶微滴中由绿色（红色）光束诱导的等温向列相→各向同性相（各向同性相→向列相）转变。这种异构化可能会减小（增加）液晶微滴与聚合物的折射率之差，从而增加（减小）扩散常数（或输运平均自由程），进而降低散射强度，从而降低随机激光强度。