Participation of electron-phonon interaction in the ultrafast self-modulation of absorption of light in GaAs. Relation of modulation of absorption with the spectrum of stimulated radiation in GaAs

Abstract

Ultrafast (varying for ∼ 1 ps) self-modulation of the absorption spectrum of light takes place during the picosecond-scale photogeneration of charge carriers and intense intrinsic stimulated radiation in GaAs. With the modulation, formation of local amplifications of absorption in the spectrum (juts), which are attributed to local depletion of electron populations in the conduction band, is implied. It is found experimentally that the location of the juts in the spectrum is repeated over the interval determined by the energy of the longitudinal optical (LO) phonon and masses of the electron and heavy hole. This circumstance confirms the previous assumption about the substantial role of the electron-(LO phonon) interaction in ultrafast self-modulation of the absorption spectrum. The previously established notion of the relation of the shape of modulation of the absorption spectrum with the shape of the time-integrated spectrum of intrinsic picosecond radiation is also expanded to the case when ultrafast self-modulation of the absorption spectrum manifests itself.