DEGENERATE 4-WAVE-MIXING IN PHENYLBENZIMIDAZOLE PROTON-TRANSFER LASER-DYES

Thermally induced phase conjugation by degenerate four-wave mixing in 1,4-dioxane solutions of the 5'-fluoro and 5'-chloro derivatives of th e 2-(2'-hydroxyphenyl) benzimidazole proton-transfer dye is reported i n the weak absorption region, low-reflectivity regime and nanosecond t ime domain. Efficiency-related aspects of the nonlinear process are in vestigated and the different contributions to the thermalization proce sses are discussed. Evidence of oscillatory acoustic modes in the nonl inear medium is presented.