Cholesteric Liquid Crystals always form a self-assembled helical structure.It produces a periodic refractive index modulation for the circular polarized light to result in a photonic band-gap.When fluorescence dyes are doped and the emission spectrum of the dye overlaps one edge of the stop-band,the photon density of states (DOS) at the edge reaches to the maximum.Thus,the laser is pumped out.Such kind of laser possesses many advantages,e.g.simple fabrication,low lasing threshold,and electrically-controllable.