Optically controlled random lasing based on photothermal effect in dye-doped nematic liquid crystals

摘要

We presented a way to control the output of the nematic liquid crystal (NLC) random laser with a response time of hundreds of milliseconds by a continuous-wave laser beam with the power of several milliwatts. The lasing intensity can be tuned continuously by variation of the control power in the range from 0 to 5 mW or the lasing output can be switched on and off by turning off and on the control beam when the control power reaches 6 mW. The control power-dependent lasing polarisation and the self-phase modulation of the control beam indicate that the photothermal effect, which leads to the change of the order of the NLC and subsequently the change of the long-range fluctuation of the dielectric tensor, is mainly responsible for the controllability of the random lasing.