Observation of Photoinduced Terahertz Gain in GaAs Quantum Wells: Evidence for Radiative Two-Exciton-to-Biexciton Scattering
arXiv:2004.11459 · doi:10.1103/PhysRevLett.125.167401
Abstract
We have observed photoinduced negative optical conductivity, or gain, in the terahertz frequency range in a GaAs multiple-quantum-well structure in a strong perpendicular magnetic field at low temperatures. The gain is narrow-band: it appears as a sharp peak (linewidth 0.45 meV) whose frequency shifts with applied magnetic field. The gain has a circular-polarization selection rule: a strong line is observed for hole-cyclotron-resonance-active polarization. Furthermore, the gain appears only when the exciton state is populated, which rules out intraexcitonic transitions to be its origin. Based on these observations, we propose a possible process in which the stimulated emission of a terahertz photon occurs while two free excitons scatter into one biexciton in an energy and angular-momentum conserving manner.
arXiv comment5 pages, 4 figures
References in corpus (9)
- Broadband THz study of excitonic resonances in the high-density regime
- Exciton Mott transition in Si Revealed by Terahertz Spectroscopy
- Exciton-Population Inversion and Terahertz Gain in Resonantly Excited Semiconductors
- Ultrafast terahertz probes of interacting dark excitons in chirality-specific semiconducting single-walled carbon nanotubes
- Observation of Coulomb-Assisted Dipole-Forbidden Intraexciton Transitions in Semiconductors
- Transient terahertz spectroscopy of excitons and unbound carriers in quasi two-dimensional electron-hole gases
- Stability of High-Density Two-Dimensional Excitons against a Mott Transition in High Magnetic Fields Probed by Coherent Terahertz Spectroscopy
- Renormalized Energies of Superfluorescent Bursts from an Electron-Hole Magneto-plasma with High Gain in InGaAs Quantum Wells
- Magnetic control of Coulomb scattering and terahertz transitions among excitons