Transient degenerate four-wave mixing in the saturable absorption of Cr4+:GSGG at 1.06 μm

Degenerate four-wave mixing (DFWM) interaction in saturable media has received considerable attention because of its potential for application to optical phase conjugation and correction of phase distortions through aberrating media. For this purpose, saturable solid-state materials, operating at the classical wavelength of neodymium lasers near λ0 = 1.06 μm, are of great interest. Here, we present DFWM in a tetravalent chromium-doped gadolinium-scandium-gallium-garnet (Cr4+:GSGG) crystal. Indeed, tetravalent chromium (Cr4+) doped crystals were recently shown to be effective solid-state saturable absorbers for neodymium lasers.1,2 Furthermore, in comparison with traditional saturable absorbers such as dyes in solution, polymeric films, and color-center materials, these crystals exhibit chemical stability, high optical damage threshold, compactness, and would enable operation at high repetition rates.