Spatial fidelity of photorefractive image correlators

• Published in: IEEE journal of quantum electronics Vol. 30; no. 12; pp. 3025 - 3032
• Main Authors: Meigs, A.D., Saleh, B.E.A.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.12.1994; Institute of Electrical and Electronics Engineers
• Subjects: Correlators; Diffraction; Equations; Exact sciences and technology; Four-wave mixing; Fundamental areas of phenomenology (including applications); Green's function methods; Image analysis; Kernel; Laser excitation; Nonlinear optics; Optical elements, devices, and systems; Optical processors, correlators, and modulators; Optics; Phase conjugation, optical mixing, and photorefractive effect; Phase conjugation, optical mixing; photorefractive and kerr effects; Photorefractive effect; Physics; Probes; Theoretical study; Optical correlator; Photorefractive effect; Four-wave mixing; Experimental study; Nonlinear optics
• ISSN: 0018-9197; 1558-1713
• DOI: 10.1109/3.362702

The set of equations describing photorefractive four-wave mixing of image-bearing beams has been solved in the presence of diffraction using a perturbation analysis assuming a strong uniform backward pump and a weak conjugate. To first order, it was found that the conjugate image is bilinearly related to the forward-pump and probe images. By using a Green's function approach, an analytical expression for the bilinear kernel was derived. This kernel, which governs the bandwidth of the conjugation system, is a function of the material parameters, the beam angles, and the crystal length. When a conjugator is used to determine the correlation between two images, the result was found to be a distorted version of the correlation image. This distortion was reduced when the image with the smallest extent was chosen as the forward-pump image.< >