Observation of phonon-assisted laser operation of Al<i>x</i>Ga1−<i>x</i>As-GaAs quantum well heterostructures

Abstract

Data are presented showing that the key to observing the phonon-assisted photopumped laser operation of narrow rectangular samples of AlxGa1−xAs-GaAs quantum well heterostructures (QWHs) is the control of the edge-to-edge resonator Q across the sample. If the sample is heat sunk in metal, with metal reflectors folded upward along the edges, the resonator Q across the sample is high, and laser operation across the sample on confined-particle states (a reference) and along the sample a phonon lower in energy (ΔE≊ℏωLO) is observed. If the sample edges across the sample are left uncoated (weakly reflecting, low Q), laser operation is observed only along the sample (longitudinal modes) but shifted (ΔE≊ℏωLO) below the confined-particle states and absorption. A QWH rectangle, with proper heat sinking and control of its edge-to-edge resonator Q, can act as a hot-phonon ‘‘spectrometer’’ if it is fully photopumped across its width and is only partially pumped along its length.