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Influence of the Surface Orientation on the Spectral Characteristics of Liquid-Crystal Photonic Crystals
The transmission, reflection, and luminescence spectra of two types of samples of a cholesteric photonic crystal are measured: with the orientation of the n director specified by the surface of the optical cell, and when the n director is disoriented on the cell surface. In samples with surface orientation, a perfect helical structure is formed with characteristic features of the luminescence spectra in the photonic band gap due to the density of photonic states. The density of photonic states is restored. The lower threshold value of the surface-anchoring potential W is estimated when the director deviates from the orientation direction given by the surface. The transformation of the luminescence spectra and the temperature dependence of the position of the bands during the transition from surface-oriented structures to disordered ones are observed.