Comparison of optical powerlimiting in bacteriorhodopsin and Azo-benzene films

Abstract

In this paper a comparison of the optical power-limiting characteristics of Bacteriorhodopsin (bR) and Azobenzcnc films is reported. An attempt is made to find out the technique which gives best powerlimiting for each of the materials. An input pump of 532 nm was used to study the first order self-diffracted output. Input beam intensity is varied over two orders of magnitude and the clamped output is measured in both the cases. The threshold intensity of limiting is governed by saturation intensity of excited state of the films and hence can be varied by choosing films of different upper state lifetimes. In both cases the output was clamped at the eye safe level of about 0.1 mW/cm2 but threshold intensities differ.