10,000 OPTICAL WRITE, READ, AND ERASE CYCLES IN AN AZOBENZENE SIDE-CHAIN LIQUID-CRYSTALLINE POLYESTER

We show far what is believed to he the first time that it is possible tu generate 10,000 rapid write, read, and erase cycles optically in an azobenzene sidechain liquid-crystalline polyester. We do this by expo sing the film alternately to visible light from an argon laser at 488 nm and ultraviolet light from a krypton laser at 351 nm. The efficienc y of the system shows several exponential decays, presumably associate d ci with the azobenzene chromophores' aligning out of the plane of th e film and the lifetime of the cis state of the azobenzene. A local te mperature increase may also play a role. However, there is enough cont rast even after 10,000 cycles to permit a clear distinction between th e maximum and the minimum anisotropy. As the anisotropy is stable betw een erasures, this method could have immediate applications for optica l storage. (C) 1996 Optical Society of America