An encrypted optical memory system that uses a wavelength code as well as input and Fourier-plane random phase codes is proposed. Original data are illuminated by a coherent light source with a specified wavelength and are then encrypted with two random phase codes before being stored holographically in a photorefractive material. Successful decryption requires the use of a readout beam with the same wavelength as that used in the recording, in addition to the correct phase key in the Fourier plane. The wavelength selectivity of the proposed system is evaluated numerically. We show that the number of available wavelength keys depends on the correlation length of the phase key in the Fourier plane. Preliminary experiments of encryption and decryption of optical memory in a LiNbO<sub>3</sub>:Fe photorefractive crystal are demonstrated.
© 1999 Optical Society of America
(070.4560) Fourier optics and signal processing : Data processing by optical means
(190.5330) Nonlinear optics : Photorefractive optics
(210.0210) Optical data storage : Optical data storage
(210.2860) Optical data storage : Holographic and volume memories
Osamu Matoba and Bahram Javidi, "Encrypted optical storage with wavelength-key and random phase codes," Appl. Opt. 38, 6785-6790 (1999)