Abstract: A device for generating radiant energy comprising a first electrode, a second electrode spaced apart from said first electrode, a material disposed between and in electrical communication with first and second electrodes, which emits radiant energy upon activation. This material is a rare earth metal oxide or a rare earth metal halide.

Abstract: A two-photon process for writing to a holographic recording medium comprising a photorefractive material doped with an excitation dopant selected from rare earth ions and an ionization dopant selected from transition metal ions or rare earth ions.

Abstract: An optical data storage system and method that utilizes the frequency dimension to increase the storage capacity significantly. The system includes a storage material, for example, in the form of a block, adapted to undergo a photo induced reaction upon exposure to light and which exhibits inhomogeneous absorption line broadening. Data bits are stored by selective photo induced reactions induced by a narrow band laser at specific frequencies within the broad inhomogeneous line. The lifetime of these photo induced data bits is of the order of years so as to provide a non-volatile storage system. In a preferred embodiment, a material is selected so that the photo induced reaction can be made reversible thereby permitting, when desired, the erasing of the data bits.