Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 13: Optical properties
HL 13.1: Talk
Tuesday, March 24, 2009, 09:30–09:45, BEY 118
THz sideband generation in multi quantum wells — Martin Wagner1, Harald Schneider1, Manfred Helm1, •Stephan Schartner2, Aaron Maxwell Andrews2, Tomas Roch2, and Gottfried Strasser2 — 1Institut für Ionenstrahlphysik und Materialforschung, Forschungszentrum Dresden-Rossendorf, Postfach 51 01 19, 01314 Dresden — 2Institut für Festkörperelektronik, TU Wien, Floragasse 7, 1040 Wien, Austria
THz sideband generation is a nonlinear mixing process where a near-infrared (NIR) laser beam is mixed with a THz beam to generate new frequencies (sidebands) ω = ω(NIR) * n * ω(THz) (with integer n). This effect has been investigated in various semiconductor systems (e. g., in bulk GaAs [1] and in multi quantum wells [2]).
We report on third-order nonlinear mixing between a NIR laser and a free-electron laser (FEL) in an undoped AlGaAs/GaAs multi quantum well. Differently from the literature where electronic and heavy-hole intersubband transitions were used, we are covering different transitions by tuning the FEL wavelength. We directly compare the n=+2 sideband generation efficiency when the FEL pumps the heavy-hole light-hole transition with the efficiency when the intraexcitonic 1s-2p transition of the heavy-hole is pumped. In the latter case the efficiency increases up to 0.2%, which is comparable to the best values achieved for an even stronger n=+1 sideband process [2].
[1] M. A. Zudov et al., Phys. Rev. B 64, 121204, 2001
[2] S. G. Carter et al., Appl. Phys. Lett. 84, 840, 2004