Abstract

Holographic data storage systems [1] require sensitive optical materials that provide some means of nondestrective readout [2]. Among the number of techniques for nonvolatile readout available [2], the sensitazation of a photorefractive medium by illumination at one wavelength, called gating, for writing at a second using a resonant two-photon process, constitutes the most versatile all-optical nondestructive method. Typically, this process consists of absorption of a photon at frequency ω₁ to generate an intermediate excited state, followed by absorption of a second at ω₂ to generate a free carrier [3, 4, 5]. Gating occurs for absorption of two photons at two different wavelengths. In the present work, we identify the critical physical characteristics of the processes that provide the simultaneous realization of true gating and writing sensitivity at a variety of frequencies, evaluate the refractive index perturbation and the response rate, and investigate the significance of the the intermediate state occupancy and the arisining nonlinear photorefractive behavior at its saturation regime.

© 1996 Optical Society of America