EFFECTIVE PHOTOCHROMIC NONLINEARITY OF DRIED BLUE-MEMBRANE BACTERIORHODOPSIN FILMS

We report the effective nonlinearity for photochromic conversion in a blue-membrane bacteriorhodopsin film hosted in a dry polyvinyl alcohol matrix. The shift in absorption maximum on photoconversion in this fi lm is larger than that of the same material in hydrated form, thus off ering a larger modulation of the refractive index. The photoexcited in dex modulation is stable for several months, which provides for hologr aphic data recording and long-term photochromic data storage. The effe ctive index modulation is experimentally measured and is in good agree ment with the theoretical predictions based on the Kramers-Kronig tran sformation. (C) 1996 Optical Society of America