Abstract

Recently, concerns have been raised about the presumed improvement in lasing performance in going from a 2D confined system to a OD confined system. Stark et al. (1992, 1993) have studied ≈10 nm GaAs/AlGaAs multiple quantum wells in a perpendicular magnetic field of 12T normal to the quantum wells. Magnetic quantization into equally spaced Landau levels plus the quantum-well quantization along the growth direction result in near-ideal quantum dots. Stark et al. have shown that the 2s magneto-exciton lives ≈ 100 ps, i. e., ≈ 1000 times longer in 12T than 0T, illustrating the phonon bottleneck. Usually hot carriers in a semiconductor excited well above the bandgap relax by a series of optical phonon emissions, thereby transferring energy rapidly (<1ps) and efficiently to the lattice. Schmitt-Rink et al. (1989), Weisbuch et al. (1991), Bockelmann and Bastard (1990), Benisty et al. (1991), and Inoschita et al. (1992) have emphasized that quantum dot quantization in all three dimensions should result in a phonon bottleneck; i.e., only by accident will the distance between energy levels be equal to the phonon energy. This could degrade the performance of a quantum dot laser considerably.

© 1995 Optical Society of America