Lasing Effect in a Binary Photoaligned Layer of a Cholesteric Liquid Crystal

The boundary conditions for the binary planar-homeotropic alignment of liquid crystals have been created using the photoalignment technique. Under these conditions, an orientational transition to the deformed lying helix state occurs in a cholesteric liquid crystal layer with the initial Grandjean texture under the action of an electric field. In the deformed lying helix state, the electric field-induced photonic stop bands exist for light propagating in the waveguide mode. In this study, the lasing effect has been investigated, which occurs at the short-wavelength edge of the tenth-order induced stop band overlapping with the amplified luminescence spectrum of a laser dye included in a cholesteric liquid crystal. It is shown that the electric field range in which the lasing effect occurs is consistent with the range of the increased diffraction efficiency of the deformed lying helix.