Discontinuous shift of lasing wavelength with temperature in cholesteric liquid crystal

The laser action in a dye-doped cholesteric liquid crystal has been investigated as a function of temperature. The discontinuous shift of the lasing wavelength has been observed. It has also been found that the shift of the stop band in the cholesteric liquid crystal is discontinuous when the size of the measured area for the spectrum is small. These results have been interpreted to originate from the disappearance of every half period of the cholesteric liquid crystal helix in the unwinding process as the temperature decreases.