Coupling of coherent longitudinal optical phonons to excitonic quantum beats in GaAs/AlAs multiple quantum wells

O. Kojima, K. Mizoguchi, and M. Nakayama
Phys. Rev. B 68, 155325 – Published 24 October 2003
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Abstract

We have investigated the dynamical properties of the coherent oscillations due to the GaAs-like longitudinal optical (LO) phonon and the quantum beat of excitons in two samples of GaAs/AlAs multiple quantum wells with different splitting energies of the heavy-hole and light-hole excitons. The coherent oscillations were measured with a reflection-type pump-probe technique. In the multiple quantum well with the splitting energy almost equal to the energy of the GaAs-like LO phonon, the intensity of the coherent LO phonon are markedly enhanced in comparison with that of the other sample, and the pump-energy dependence of the intensity of the coherent GaAs-like LO phonon shows similar profile to that of the excitonic quantum beat. Moreover, the intensity of the coherent GaAs-like LO phonon is linearly increased with an increase in pump power, which is contrary to a usual generation mechanism, i.e., the displacive excitation of coherent phonon leading to a square dependence. These facts indicate that the excitonic quantum beat acts as a driving force for the coherent GaAs-like LO phonon in the case that the splitting energy of the heavy-hole and light-hole excitons is almost equal to the LO phonon energy.

  • Received 13 May 2003

DOI:https://doi.org/10.1103/PhysRevB.68.155325

©2003 American Physical Society

Authors & Affiliations

O. Kojima*, K. Mizoguchi, and M. Nakayama

  • Department of Applied Physics, Graduate School of Engineering, Osaka City University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan

  • *Electronic address: kojima@a-phys.eng.osaka-cu.ac.jp

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Issue

Vol. 68, Iss. 15 — 15 October 2003

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