Lasing in dye-doped cholesteric liquid crystals: Two new tuning strategies

Tuning of a dye-doped cholesteric liquid crystal mirrorless laser in the violet-ultraviolet wavelength range is achieved using two different strategies for controlling the periodicity of the cholesteric helical structures. Both methods are shown produce a shift of the lasing wavelength by 30-40 nm, and smooth variation of the helical pitch can be achieved.