Amplification lengths of spectral components of intrinsic stimulated picosecond emission. Dependence of the characteristic relaxation time of these components on their amplification lengths. Relation between stimulated and spontaneous emission spectra in GaAs

The high-power picosecond optical pumping of a thin GaAs layer generates intense picosecond stimulated emission. The emission spectrum is a light continuum. Based on the results of previous experimental work, the following is carried out. (a) The amplification lengths of the emission spectral components, i.e., the different distances over which different emission components are amplified in the active medium produced by pumping and (b) the dependences of the characteristic relaxation time of emission components on their gain lengths are estimated. It is shown that the spectrum of the product of the gain length and the gain linearly relates the spectra of the spontaneous and stimulated emission of GaAs. This relation is established upon gain saturation which is evidenced by a dip in the gain spectrum, “burned out” by intense emission.