We examine optically induced birefringence in semicrystalline azopolymer films that are held at glass-transition temperature <i>T</i><sub><i>g</i></sub>. The birefringence increases markedly after interception of the pump beam; the saturation value depends on exposure time. In addition, the induced birefringence is completely erased by irradiation with a circularly polarized beam at <i>T</i><sub><i>g</i></sub>. Using this thermally assisted method, we demonstrate the holographic recording of a test image. The intensity of the diffracted beam also increases after interception of the writing beams. Furthermore, the retrieved image is found to have a resolution of ~30 lp/mm. This resolution is comparable with that of the optical setup that is used. Accordingly, the thermally assisted recording by use of semicrystalline azopolymers is a promising method for reversible holographic storage.
© 2002 Optical Society of America
(090.2900) Holography : Optical storage materials
(160.5470) Materials : Polymers
(210.2860) Optical data storage : Holographic and volume memories
(210.4810) Optical data storage : Optical storage-recording materials
Jiro Minabe, Katsunori Kawano, and Yasunari Nishikata, "Thermally Assisted Recording of Holographic Gratings in Semicrystalline Azobenzene-Containing Polymers," Appl. Opt. 41, 700-706 (2002)