Ultraviolet lasing in cholesteric liquid crystals

We report the observation of stimulated emission and mirrorless lasing in p ure cholesteric liquid crystals. The lasing action is attributed to the com bination of the fluorescence and the distributed feedback that are due to t he inherent periodic structure of the liquid crystal. If the reflection ban d matches the intrinsic emission of the cholesteric liquid crystal, the cry stal becomes a natural laser material, which will self-lase, without any op tical elements or the addition of dyes, under picosecond excitation at 355 nm. Samples have been made to lase at different wavelengths in the near UV by shifting of the edge of the reflection band in the range of 385-405 nm. Typical linewidths observed are of the order of 0.5 nm. (C) 2001 Optical So ciety of America.