Raman scattering from optically pumped electron-hole plasma in insulating GaAs

We measured the single particle Raman Scattering from an optically pumped electron-hole plasma in bulk insulating GaAs, using IR radiation of 1.06 μm to both excite and probe the plasma. The relevant theory is derived in terms of a Landau generalized quasi-particle picture and we show how many-body effects are discernible in the spectrum. The results of the experiment lend independent support to the model of two-photon absorption in GaAs and allowed us to place a lower bound of 1 × 10¹⁶ cm^?3 for the threshold of saturation effects in the density of photo-generated electron-hole pairs in bulk GaAs.