High-density optical storage based on nanometer-size arsenic clusters in low-temperature-growth GaAs

Nanometer-size arsenic clusters in low-temperature-growth molecular beam epitaxy GaAs provide the basis for a high-density optical storage medium. The material exhibits a large Franz-Keldysch electro-optic effect at room temperature. Charge storage on the clusters and the excitonic electro-optic properties of the material combine to make a low-power high-density photorefractive storage medium. The ultrafast lifetimes of the photogenerated carriers produce excellent spatial resolution during the writing of holographic space-charge gratings. Fringe spacings as small as 0.6 μm can be supported in this material, yielding an optical data density greater than 108 bits/cm2. The saturation intensity is 2 mW/cm2 with a storage time of 2 ms.