<title>Material for optical memory</title>

Abstract

A new and highly promising optical memory technology based on a proprietary metal oxide material has been developed in an on-going Rome Laboratory/Laser Chemical Corporation effort. Metal oxide materials are being evaluated for use as optical disk media and optically addressable electronic memory. Simultaneously presented Nd:YAG laser beams at 1.06 micrometer and doubled YAG at 532 nm are used to write blue bits on the metal oxide material. The 532 nm radiation causes electron transfer from oxygen to metal atoms. This weakens the metal- oxygen bonds, allowing lattice oxygen to be driven out. This additional electron then can move from one metal atom in the written spot to another. This process, called 'intervalence transfer,' involves absorption of visible light, making the material appear a different color then the unwritten material. The color change is permanent until the material is reheated to a temperature greater than 350 degrees Celsius either in an oven for global erase, or by a concentrated infrared laser beam for spot erase. Multiwavelength schemes are incorporated into optically reading the bits. Design, fabrication and evaluation of WO<SUB>3</SUB> thin films is discussed.