Mid-infrared optical emission due to intersubband transitions between excited conduction subbands of a coupled quantum well structure is studied. The emission process is based on optical pumping of free carriers from the ground subband into the third subband followed by a radiative transition from the third subband into the second subband and a fast phonon assisted relaxation into the ground subband. We have observed spontaneous emission at 14 μm that persists up to room temperature. Our results indicate that population inversion between conduction subbands and large stimulated gain can be achieved.
- Intersubband transitions
- Optical properties of quantum wells
- Semiconductor lasers
ASJC Scopus subject areas
- Materials Science(all)
- Condensed Matter Physics
- Electrical and Electronic Engineering