Holographic fabrication of polarization selective diffractive optical elements on azopolymer film

Abstract

Polarization selective grating elements are fabricated on azopolymer film by superposing an interference pattern due to +45:-45° polarized light beams. The transmission type grating shows unique features due to the simultaneous presence of bulk birefringence grating and surface relief grating. The birefringence grating is formed due to light induced reorientation of the azobenzene chromophores. The surface relief grating, however, is formed by light driven polymer mass transport. Diffraction from the grating with linear and orthogonally polarized read beams show polarization discrimination capabilities. Also, an unpolarized read beam upon transmission through the grating becomes predominantly linearly polarized in the transmitted and diffracted orders.