Efficiency of nonlinear radiation conversion by phasematched third harmonic generation in a cholesteric liquid crystal

An investigation was made of the efficiency of third harmonic generation in a cholesteric liquid crystal as a function of the thickness of a nonlinear layer of this crystal. The phase-matching conditions in third harmonic generation were satisfied using the temperature dependence of the helix pitch of the crystal. The maximum third harmonic power was obtained using liquid-crystal cells about 10 μ thick. The homogeneity of the helix was disturbed in thicker liquid-crystal layers and this reduced the efficiency of third harmonic generation. The absolute value of the third-order nonlinear susceptibility of the liquid crystal was determined. The possibility of constructing compact liquid-crystal film converters of laser radiation was considered.