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Two-photon photocurrent studies of electron intersubband dynamics in multiple quantum wells

Schneider, H.

Quantum wells comprising three equidistant subbands, two of which are bound in the well and the third one in the continuum, result in a resonantly enhanced coefficient for two-photon absorption, which is by six orders of magnitude stronger than in usual semiconductors. Exploiting this nonlinearity in two-photon detectors, quadratic autocorrelation of a free-electron laser has recently been demonstrated at room temperature [1]. Temporal resolution of such a two-photon autocorrelator is only limited by the sub-ps intrinsic time constants of the intersubband transition, namely the intersubband relaxation time and the phase relaxation time. Using sub-ps mid-infrared pulses, the approach allows us to determine systematically the dependence of these time constants on structural parameters, and to discriminate between different scattering processes [2].
[1] H. Schneider, H. C. Liu, S. Winnerl, O. Drachenko, M. Helm, J. Faist, Appl. Phys. Lett. 93, 101114 (2008).
[2] H. Schneider, T. Maier, M. Walther, H. C. Liu, Appl. Phys. Lett. 91, 191116 (2007).

Keywords: intersubband transition; two-photon absorption; quantum well infrared photodetector; phase relaxation; autocorrelation

  • Invited lecture (Conferences)
    International Workshop on Nonequilibrium Nanostructures (NONNA'08), 01.-06.12.2008, Dresden, Germany

Permalink: https://www.hzdr.de/publications/Publ-11960
Publ.-Id: 11960