Circularly polarized unidirectional lasing from a cholesteric liquid crystal layer on a 1-D photonic crystal substrate

We present the results of a study of highly circularly polarized unidirectional lasing emission from an organic lasing device that consisted of a dye-doped cholesteric liquid crystal (CLC) layer on a 1-dimensional (1-D) photonic crystal (PC) reflecting mirror substrate. Unidirectional lasing was demonstrated successfully for this device structure at the wavelength of the high-energy band edge of the CLC layer. It was also shown that circularly polarized lasing emission was produced from the lasing device at a low lasing threshold of 2.5 mJ/pulse. The handedness of lasing light corresponds to the handedness of the used CLC layer with a high ratio of intensity between right- and left-handed circularly polarized lasing light over of up to 3.7. These results show that the CLC/1-D PC device enables unidirectional lasing with highly circularly polarized laser emission.