Terahertz Electron-Hole Recollisions in GaAs/AlGaAs Quantum Wells: Robustness to Scattering by Optical Phonons and Thermal Fluctuations

摘要

Electron-hole recollisions are induced by resonantly injecting excitons with a near-IR laser at frequency ƒ_(NIR) into quantum wells driven by a 10 kV/cm field oscillating at ƒ_(THz) = 0.57 THz. At T = 12 K, up to 18 sidebands are observed at frequencies ƒ_(sideband) = ƒ_(NIR) + 2nƒ_(THz), with - 8 ≤ 2n ≤ 28. Electrons and holes recollide with total kinetic energies up to 57 meV, well above the E_(LO) = 36 meV threshold for longitudinal optical (LO) phonon emission. Sidebands with order up to 2n = 22 persist up to room temperature. A simple model shows that LO phonon scattering suppresses but does not eliminate sidebands associated with kinetic energies above E_(LO).