Terahertz Electron-Hole Recollisions In Gaas/Algaas Quantum Wells: Robustness To Scattering By Optical Phonons And Thermal Fluctuations

Electron-hole recollisions are induced by resonantly injecting excitons with a near-IR laser at frequency f(NIR) into quantum wells driven by a 10 kV/cm field oscillating at f(THz) = 0.57 THz. At T = 12 K, up to 18 sidebands are observed at frequencies f(sideband) = f(NIR) + 2nf(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.