An experimental study is carried out on the diffraction and angular selectivity properties of gratings for a wide range of angles of incidence in three-dimensional space. Results for three grating types are presented: nonslanted volume gratings, slanted volume gratings, and hybrid structures. The study encompasses a wide range of directions of radiation incidence on structures and reveals grating orientations that can provide maximal diffraction efficiency for angles of incidence of more than 70°. Obtained data are used to assess the efficiency of diffractive deflectors on the basis of the considered structures, taking into account the trajectory of the Sun as applied to solar-energy problems.
Tunable Polarization Volume Gratings based on Blue Phase Liquid Crystals
