Spectral and Polarization Characteristics of the Light Passing through a Cholesteric Photonic Crystal

Abstract

Combined optical studies of a cholesteric photonic crystal are performed: the transmission spectra and the rotation of the plane of polarization of light (RPPL) spectra of the crystal are recorded, and the polarization characteristics of the light having passed through the photonic crystal are measured. The RPPL spectra have specific features related to the presence of a photonic quasi-band gap. The photonic density of states and its transformation with the photonic crystal temperature and thickness are determined. The ellipticity (ratio of the minor to the major axis of ellipse) of the light having passed through the sample is maximal at the center of the band gap and decreases when the distance from the band gap increases. At the center of the photonic quasi-band gap, the ellipticity increases with increasing photonic crystal thickness L and decreasing temperature, and it is close to a circular one in samples with L > 5 μm. The results obtained are compared with the existing theories, the analytical expressions derived from the Maxwell equations, and the results of numerical calculations performed by the 4 × 4 Berreman matrix method