We present saturation absorption studies of the HH1 ? LH1 intersubband transition in a 70 Å p-type GaAs/AlGaAs multi-quantum well. The subband separation in this sample, with strongly non-parabolic bands, varies from 26 meV at k = 0 to 16 meV at the Fermi wave vector. The absorption behaviour of this transition is studied over a range of four orders of magnitude of intensity of incident THz radiation. The results are analysed within the contexts of a simple two-level model and an instantaneous thermalization model. The results indicate that the lifetime obtained with these models is limited by the pulsewidth, i.e. is greater than 1.7 ps. This places a lower limit on the energy relaxation time for transitions below the LO-phonon energy. © 1998 Elsevier Science B.V. All rights reserved.
|Number of pages||5|
|Journal||Physica E: Low-Dimensional Systems and Nanostructures|
|Publication status||Published - 15 Jul 1998|
- Energy relaxation
- p-type quantum well
- Saturation absorption
- Terahertz radiation