The generation of multiple waves during near-oblique incidence of a
weakly focused beam on photorefractive iron-doped lithium niobate in a typical reflection geometry configuration is studied. It is shown that these waves are produced through two-wave coupling (self-diffraction) and four-wave mixing (parametric diffraction). One of these waves, the stimulated photorefractive backscatter produced from parametric diffraction, contains the self-phase conjugate. The dynamics of six-wave mixing and its dependence on crystal parameters, angle of incidence, and pump power are analyzed. What we believe to be a novel order analysis of the interaction equations provides further insight into experimental observations in the steady state. The quality of the backscatter is evaluated through image restoration, interference experiments, and visibility measurement.
Reduction of two-wave coupling may significantly improve the quality of the self-phase conjugate.
© 2007 Optical Society of America
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(190.5040) Nonlinear optics : Phase conjugation
(190.5330) Nonlinear optics : Photorefractive optics
(190.7070) Nonlinear optics : Two-wave mixing
Original Manuscript: November 1, 2006
Revised Manuscript: May 24, 2007
Manuscript Accepted: May 30, 2007
Published: August 16, 2007
M. A. Saleh, P. P. Banerjee, J. Carns, G. Cook, and D. R. Evans, "Stimulated photorefractive backscatter leading to six-wave mixing and phase conjugation in iron-doped lithium niobate," Appl. Opt. 46, 6151-6160 (2007)