|Title||Saturation absorption studies of intersubband relaxation rates in a p-GaAs/AlGaAs QW using a free electron laser|
|Publication Type||Journal Article|
|Year of Publication||1998|
|Authors||B.E Cole, C Langerak, B.N Murdin, C.D Bezant, J.M Chamberlain, C.R Pidgeon, M. Henini, V. Nakov|
We present saturation absorption studies of the HH1 --> LH1 intersubband transition in a 70 Angstrom 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 lime for transitions below the LO-phonon energy. (C) 1998 Elsevier Science B.V. All rights reserved.
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