Effects of separated absorption and emission spectra on degenerate four-wave mixing in organic dyes

Abstract

Degenerate four-wave mixing in a separated absorption-gain system, such as that of an organic dye, is studied by using a four-level model. The effects of the nonlinearity arising from the displaced emission spectrum are found and compared with the results of the two-level model of Abrams and Lind [ Opt. Lett.2, 94 ( 1978); Opt. Lett.3, 205 ( 1978)]. A nonsymmetric saturation behavior over the width of the absorption line is shown to exist that can be detrimental to the phase-conjugate reflectivity. Otherwise, minor differences are seen from the two-level case.