Abstract
We demonstrate the potential for laser operation at far-infrared wavelengths (30-300 μm, 1-10 THz) by using intersubband emission in four-level GaAs/AlGaAs asymmetric (stepped) quantum wells. Achieving population inversion in these devices depends critically on the lifetimes of the nonradiative intersubband transitions, and so we have performed detailed calculations of electron-electron and electron-phonon scattering rates. Our four-subband structures show potential for the realization of room temperature lasing, unlike previously considered three-subband structures which did not give population inversions except at impractically low electron densities and temperatures. Auger-type electron-electron interactions involving the highly populated ground subband effectively destroyed the population inversion in three level systems, but in these four subband structures the inversion is maintained by strong phonon-mediated depopulation of the lower laser level. The largest population inversions are calculated at low temperatures (<30 K), but for the structures with higher emission energies, room temperature (300 K) operation is also predicted.
Original language | English |
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Pages (from-to) | 23-28 |
Number of pages | 6 |
Journal | Journal of Applied Physics |
Volume | 85 |
Issue number | 1 |
Early online date | 16 Dec 1998 |
DOIs | |
Publication status | Published - 1 Jan 1999 |
Externally published | Yes |