Abstract
A dense hot electron-hole plasma and picosecond superluminescence appeared upon pumping of a GaAs layer by a picosecond (ex) optical pulse. The distribution of electrons over the conduction band was modulated with a period equal to the LO-phonon energy. The effect of additional pumping of GaAs (p i ) by an optical pulse with a photon energy of ℏωp<ℏωex−0.1 eV on the superluminescence was investigated. In the case of simultaneous pumping by ex and p i pulses, a local maximum or minimum appeared in the spectrum of relative increase in the superluminescence energy at the photon energy, which corresponds to the peak in the superluminescence-energy spectrum of the active region of the GaAs layer. The local maximum appeared when the electrons that were excited by the p 1 pulse to the level with a depleted population emitted LO phonons (one phonon per each electron) and recombined. The local minimum appeared when electrons were excited by the p 2 pulse to the level with the Fermi population. The spectral width of the local maximum and minimum turned out to be narrower than the calculated width of the energy level from which the electrons recombine.