Patent ID: 6157470
Filing Date: 2000-12-05
Classification: G03H

Abstract:
A method for recording information in an optical material, comprising:preparing the optical material to have first and second types of dopants that are operable to produce charge carriers to a common band in response to radiation of specified wavelengths and to recombine with charge carriers in said common band, said first type of dopants having a first dopant energy level below said common band by a first energy gap greater than a second energy gap of a second dopant energy level of said second type of dopants below said common band;illuminating the optical material by a sensitizing beam of a first wavelength to simultaneously excite charge carriers from both said first and second types of dopants to said common band; andilluminating the optical material by a signal beam and a reference beam of a second wavelength that is longer than said first wavelength and exciting only charge carriers from said second type of dopants to said common band, said signal and reference beams producing an interference pattern in the optical material,simultaneously illuminating the optical material by said sensitizing beam, said signal beam, and said reference beam to produce a spatial charge carrier distribution indicative of said interference pattern and storing information carried by said signal beam.