Lasing from photonic structure: Cholesteric-voltage controlled nematic-cholesteric liquid crystal

Experimental investigation and numerical simulation have been made of spectral and lasing properties of thin planar hybrid structures consisting of two layers of a cholesteric liquid crystal (ChLC) and a homogeneously aligned layer of a nematic liquid crystal between them. The light optical path in the nematic layer was controlled by an electric field. In the reference structure the ChLC layers were not doped, and the field controlled transmission spectra have been studied in detail. In the other two structures, both the ChLC layers were doped by the same laser dye (but different in the two structures) and the feedback necessary for lasing was controlled by the field induced phase retardation of the nematic layer. Therefore, the field control of the lasing spectra has been demonstrated. Numerical simulations of the transmission and lasing spectra are in good agreement with experimental data. The multilayer device described can be used as a field controllable planar microlaser.