Peculiar behaviour of optical polarization gratings in light-sensitive liquid crystalline elastomers

The angular dependence of the diffraction efficiency of volumetype gratings recorded in a single-domain light-sensitive liquid elastomer was investigated. Usually this dependence is expected be very similar for intensity gratings and for polarization gratings. , our measurements resolved a profound difference between the types of the gratings: a typical Bragg peak of the diffraction efficiency observed only for intensity gratings, while polarization gratings exhibit a dip at the Bragg angle. The appearance of this dip is explained by anisotropic optical absorption of the actinic light during the process.