Picosecond nonlinear absorption and four-wave mixing in GaInAsP

We report the first λ∼1.5 μm picosecond near-band-gap nonlinear absorption and degenerate four-wave mixing (DFWM) experiments in room-temperature GaInAsP using a mode-locked color center laser. The temporal, spectral, and pump energy dependences of the nonlinear signals are investigated. Nonlinear absorption cross sections σeh as large as −5.7×10−15 cm2 are obtained from the pump probe results, while effective nonlinear cross sections σeff as large as 7.8×10−16 cm2 (corresponding to a steady ‖χ(3)‖∼3.8×10−3 esu for a 20-ns relaxation time) are measured in the DFWM experiments.