Optical dephasing in saturable-absorbing organic dye IR140

Room-temperature degenerate four-wave mixing in the forward two-pulse geometry, has been performed on a jet of organic saturable-absorbing laser dye IR140 dissolved in dimethylsulfoxide and ethylene glycol. Numerical solutions to the optical Bloch equation were fitted to the experimental data in order to extract a value of T2=50(plus-minus)5 fs for the homogeneous dephasing time; this value is comparable to those measured for similar organic dyes using other techniques.