Abstract

Intersubband transitions in quantum-well (QW) structures have attracted much interest because of their potential application to infrared detectors, modulators, harmonic generators, and lasers. We have recently fabricated GaAs/AlGaAs potential- inserted quantum-well (PI-QW) structures in which a very thin AlAs layer is inserted at the center of the well, and we have demonstrated shifts of intersubband transition energy without changing the position of the second subband.^1,2 In this paper we present a novel asymmetric double-quantum-well structure consisting of a PI-QW and a normal QW of the same thickness. This structure easily makes resonant coupling of the second subbands of the two wells, as shown in Fig. 1. This structure is designed so that the first and second intersubband transition energies are in the photon-energy region of the CO₂ laser. We investigated photoluminescence spectra of the potential-inserted asymmetric double quantum wells (PI-DQW’s) under infrared optical excitation by a CO₂ laser at the intersubband resonance in order to control the electron population.

© 1993 Optical Society of America