Undressing a Collective Intersubband Excitation in a Quantum Well

K. Craig; B. Galdrikian; J. N. Heyman; A. G. Markelz; J. B. Williams; M. S. Sherwin; K. Campman; P. F. Hopkins; A. C. Gossard

doi:10.1103/PhysRevLett.76.2382

Undressing a Collective Intersubband Excitation in a Quantum Well

K. Craig, B. Galdrikian, J. N. Heyman, A. G. Markelz, J. B. Williams, M. S. Sherwin, K. Campman, P. F. Hopkins, and A. C. Gossard

Phys. Rev. Lett. 76, 2382 – Published 25 March 1996

Abstract

We have experimentally measured the 1–2 intersubband absorption in a single 40 nm wide modulation-doped ${Al}_{0.3} {Ga}_{0.7} As / GaAs$ square quantum well as a function of frequency, intensity, and charge density. The low-intensity depolarization-shifted absorption occurs near $80 {cm}^{- 1}$ (10 meV or 2.4 THz), nearly 30% higher than the intersubband spacing. At higher intensities, the absorption peak shifts to lower frequencies. Our data are in good agreement with a theory proposed by Załużny, which attributes the redshift to a reduction in the depolarization shift as the excited subband becomes populated.

Received 7 September 1995

DOI:https://doi.org/10.1103/PhysRevLett.76.2382

Authors & Affiliations

K. Craig¹, B. Galdrikian¹, J. N. Heyman², A. G. Markelz¹, J. B. Williams¹, M. S. Sherwin¹, K. Campman³, P. F. Hopkins³, and A. C. Gossard³

¹Department of Physics and Quantum Institute, University of California at Santa Barbara, Santa Barbara, California 93106
²Department of Physics and Astronomy, Macalester College, St. Paul, Minnesota 55105
³Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106