Investigation of birefringence and surface relief grating formation in azopolymer films

Abstract

Polarization holography is used to study the dynamics of optically induced gratings in azobenzene functionalized polymer films. The simultaneously formed birefringence grating (BG) and surface relief grating (SRG) are investigated by probing the grating formation process with orthogonal linearly polarized beams for different polarization combinations of the writing beams. Our experimental results indicate that for early writing times, vertically polarized beam diffract from the BG while the horizontally polarized beam gets diffracted predominantly from the SRG. Explanation based on the total electric field vector pattern due to interference of polarized beams and its effect on the material gives an insight into the physical processes responsible for the dual-grating formation.