Influence of Thickness of Methyl-Orange-Doped Polyvinyl Alcohol Film on Phase Conjugate Matched Filtering

Abstract

Phase conjugate matched filtering was performed with optical phase conjugation in Fourier-transforming backward degenerate four-wave mixing. A methyl-orange-doped polyvinyl alcohol (MO/PVA) film was used as a phase conjugator. The influence of the film thickness upon decay of a correlation signal due to phase mismatching was investigated. The thickness was varied from 15 μm to 90 μm. Reduction of the film thickness relaxes the tolerance for phase mismatching, which also occurs when a large reference picture is placed in a pump beam or when a reference picture shifts from the optical axis of the pump beam. Using a MO/PVA film of 15 μm thickness, we obtained allowable angles of 3.4° for a horizontally expanded reference picture and larger than 4.3° for a vertically expanded reference picture, assuming about 40% reduction of a correlation signal is allowable.