Real time monitoring of SRG and BG on an azobenzene polymer film

Abstract

Azo-containing polymers have received much attention over the past decade because of their nice optical properties. It is well known that surface relief grating(SRG) and birefringence grating(BG) can be formed when two polarized beams are illuminated on an azo-containing polymer. The mechanism of SRG and BG formation is crucial for the applications to various optical devices. In this presentation, two types of photo-induced gratings, SRG and BG were formed on an azobenzene polymer film by two-beam interference method with left and right circularly polarized recording beams. In order for real time monitoring of SRG and BG separately, two methods, diffraction efficiency measurement method and real time imaging method were examined. The spatial distributions of SRG and BG measured by the two methods were analyzed and compared with each other. This work is useful to clarify the SRG formation which mechanism is still not clear.