Intersubband Transitions in Quantum Wells.

Intersubband transitions in quantum-well structures have been studied both experimentally and theoretically. Far -infrared (FIR) intersubband emission has been observed in an optically pumped GaAs/AlGaAs coupled-quantum well (CQW) structure. Intersubband absorptions have been observed in GaAs/AlGaAs coupled-quantum well (CQW) structures. A self-consistent Hartree model which predicts the transition energies to within 3% and the transition strengths to within 20% has been developed, and the role of the exchange interaction is discussed. The possibility of creating an optically -pumped FIR laser using the intersubband transitions of a CQW structure was investigated using this model. It was concluded that such a laser is feasible, but not practical when compared to the existing sources of coherent FIR radiation. Modifications to improve the predicted performance were recommended. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253 -1690.).