Tailoring of random lasing characteristics in dye-doped nematic liquid crystals

Amplified spontaneous emission and random lasing are investigated in random systems with dye-doped nematic liquid crystals. And that temporal stability of random lasing is analyzed. The influence of pumping polarization as well as the multiple scattering and reflection between boundaries on the emission behavior and the formation of coherent feedback is investigated in detail. For freely suspended samples, certain emission wavelength can be obtained by changing the pump wavelength. This feature is useful in making wavelength-tunable lasers. Moreover, as the pumping thickness of wedge sample increases, the emission spectrum is red shifted and the average spacing of adjacent spikes decreases. This property can be applied in laser mode selection, i.e., the number of modes within certain wavelength range can be chosen.