Population inversion in optically pumped asymmetric quantum well terahertz lasers

P. Harrison, R. W. Kelsall

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


Intersubband carrier lifetimes and population ratios are calculated for three- and four-level optically pumped terahertz laser structures. Laser operation is based on intersubband transitions between the conduction band states of asymmetric GaAs-Ga1-xAlxAs quantum wells. It is shown that the carrier lifetimes in three-level systems fulfill the necessary conditions for stimulated emission only at temperatures below 200 K. The addition of a fourth level, however, enables fast depopulation of the lower laser level by resonant longitudinal optical phonon emission and thus offers potential for room temperature laser operation.

Original languageEnglish
Pages (from-to)7135-7140
Number of pages6
JournalJournal of Applied Physics
Issue number11
Publication statusPublished - 1 Jun 1997
Externally publishedYes


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