Abstract

Intersubband scattering is a process of great importance, especially for the understanding of the possible performances of devices such as quantum cascade lasers.¹ The involved time scales are relatively well understood in the case of intersubband separation larger than the energy of the optical phonons² and correspond well to the computed interaction with LO phonons. In the case of intersubband separation smaller than the energy of the LO phonon, the results are quite widespread (from 1 ps to 1 ns).^3,4 We have studied in great detail the case of intersubband relaxation in large wells (~ 220 Å) using luminescence with resonant excitation and femtosecond (upconversion) or picosecond resolution (streak camera).

© 1998 Optical Society of America