Electric control of lasing from multiple-scattering structure of dye-doped liquid crystal

Abstract

We have performed the electric control of random lasing in a dye-doped smectic A liquid crystal. The liquid crystal used this study was a mixture of 4'-octyloxy-4-biphenylcarbonitrile and a chiral dopant, S1011 (2wt%). As a fluorescent dye, pyrromethene597 was doped in this liquid crystal at a concentration of 0.7 wt%. With the application of an electric field, when the excitation energy increased, the emission abruptly intensified and the bandwidth drastically shrunk. This random lasing can be controlled by the electric field with a threshold of 4 V/micron. In contrast to the previous report by Morris et al., our sample showed nonlinear amplification even in the electric field induced homeotropic state.