Maximizing the population inversion by optimizing the depopulation rate in far-infrared quantum cascade lasers
✍ Scribed by K. Donovan; P. Harrison; P. Kinsler; R.W. Kelsall
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 58 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
Electron-LO phonon and electron-electron transition rates are calculated for a three-level triple quantum well system to be employed as a laser operating in the far-infrared (30-300 µm) or terahertz (1-10 THz) region. The population ratio is determined from the ratio of the carrier lifetimes in levels |3 and |2 . The most effective way of depopulating the lower laser level is found to be by LO phonon scattering to a strongly coupled state, as occurs at an anticrossing. Back scattering of carriers from level |1 to level |2 is significant at room temperature, but a population ratio of approximately 5 is possible nonetheless.