Phototunable lasing in dye-doped cholesteric liquid crystals

In this letter, we report the results of phototunable lasing in dye-doped cholesteric liquid crystals (DD-CLC). Photoexcitation of DD-CLC films gives rise to laser emission in the violet-UV range. Control of the structure of the chiral dopant driven by UV phototransformation is exploited in order to obtain a permanent variation of the cholesteric pitch. Laser emission wavelength tuning, by means of photoinduced shifting of the selective reflection band of the cholesteric liquid crystals is established. A tuning interval of about 35 nm, in the wavelength range of 385-415 nm, is observed.