Parametric Coupling in an Optically Excited Plasma in Ge

Abstract

Recent measurements of apparent absorption saturation and ultrafast relaxation in Ge have been reinterpreted as a parametric coupling between optical beams due to an index grating produced by a high-density electron-hole plasma. A sharp spike in probe-beam transmission of width 2 psec observed near zero time delay between a strong pumping and a weak probing beam has been shown to be the autocorrelation of the optical electric fields. In addition, evidence of a true saturation effect with a much longer recovery time is observed.