Nonlinear spectroscopy in InGaAs/InP multiple quantum wells.

Intensity-dependent absorption, low-intensity pump-and-probe and forward-degenerate-four-wave-mixing experiments were performed in InGaAs/InP multiple -quantum-well structures, whose fundamental bandgaps lie in the wavelength region of low loss and low dispersion for silica-based optical fibers. The results if these experiments are self-consistent. The nonlinear susceptibility chi sup (3) was found to be 0.08 esu, which is greater than that for GaAs/GaAlAs MQW. The saturation intensity is 200W/cm sup 2 (for 30 nsec carrier lifetime). The absorption can be saturated almost completely near the n = 1 heavy-hole exciton peak. The large nonlinearity and good saturation property make InGaAs/InP MQW a promising candidate for all-optical switching.