All-optical coherently controlled terahertz ac charge currents from excitons in semiconductors

Christian Sames, Jean-Michel Ménard, Markus Betz, Arthur L. Smirl, and Henry M. van Driel
Phys. Rev. B 79, 045208 – Published 22 January 2009

Abstract

We have investigated the influence of excitonic effects on two-color coherently controlled electrical currents in semiconductors. We produce currents in CdSe and CdTe at temperature of 10 or 80 K using quantum interference between single- and two-photon absorption of fundamental and second-harmonic 150 fs optical pulses tuned over a wide energy range. Current injection is monitored via the emitted terahertz generation. For the highest photon energies wherein the injected electron-hole kinetic energy is large compared to the exciton binding energy, “dc” electrical current injection is observed and expected within the independent-particle approximation in which phase control of the current magnitude is governed by the optical phases only. However, as the photon energy decreases to the band-gap energy, features appear in the terahertz emission pattern that increasingly signal the breakdown of this model, in agreement with recent theoretical calculations that incorporate electron-hole interactions. In particular, when the excitation pulse bandwidth spans the 1s2p exciton states, the terahertz emission characteristics are consistent with a theoretically predicted ac electrical current injection in which the phase of the current—but not its amplitude—is controlled by the relative phase of the optical pulses.

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  • Received 22 September 2008

DOI:https://doi.org/10.1103/PhysRevB.79.045208

©2009 American Physical Society

Authors & Affiliations

Christian Sames1, Jean-Michel Ménard1, Markus Betz1, Arthur L. Smirl2, and Henry M. van Driel1,*

  • 1Department of Physics and Institute for Optical Sciences, University of Toronto, Toronto, Ontario, Canada M5S 1A7
  • 2Laboratory for Photonics and Quantum Electronics, 138 IATL, University of Iowa, Iowa City, Iowa 52242, USA

  • *Corresponding author; vandriel@physics.utoronto.ca

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Issue

Vol. 79, Iss. 4 — 15 January 2009

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