Wide-Range Position-Tuning Lasers in Cholesteric Liquid Crystal

A wedge liquid crystal (LC) cell is designed and manufactured, and a dye-doping cholesteric LC laser formed by mutual diffusion of the cholesteric LC with different pitches. A laser that is tunable in the 558–624 nm range is obtained under moderate optical pumping, with a tuning range of 66 nm and a laser spectral tuning resolution of 1 nm, so as to achieve the spatial position of a wide range of tunable lasers. The laser threshold varies at different positions in the device, and the lasing thresholds of the dye-doping cholesteric LC cell at 40 and 9 μm are 18 and 25 μJ/pulse, respectively. The density of the photonic states is simulated in the experimental sample, and the result is in good agreement with the photonic band gap in our experiment, which not only explains the low-threshold laser at the band gap edge, but also predicts the experiment.