External strain engineering of the optical response of (Al,Ga)As/GaAs microdisk lasers

ORAL

Abstract

Recent studies show that semiconductor microcavities provide unexpected ways of controlling electron spin coherence via light-matter interactions in confined geometries [S. Ghosh et al., cond-mat/ 0509500], suggesting new routes towards spin-based quantum information processing. Here, we use optical spectroscopy to study the effects of external strain on lattice-matched (Al,Ga)As/GaAs microdisk lasers. We demonstrate that the encapsulation of such lasers with SiN$_x$ allows systematic strain engineering of steady state optical characteristics, where measurements of spontaneous emission show that GaAs quantum wells in the active region of the microdisks experience strain from both the SiN$_x$ and the free standing disk shape, and measurements of stimulated emission show that the laser threshold decreases with the magnitude of net compressive strain. Further, we also explore related modifications in the electron spin coherence time. Work supported by DARPA/QUIST and NSF.

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Authors

  • Xia Li

  • M. H. Mikkelsen

  • Sayantani Ghosh

    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA 93106, USA

  • David Awschalom

    • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, CA 93106

  • Nitin Samarth

    • Materials Research Institute, Penn State University and Center for Spintronics and Quantum Computation, University of California-Santa Barbara
    • Physics Department, Penn State University, University Park PA 16802
    • Physics Department and Materials Research Institute, Penn State University, University Park PA 16802.
    • Physics Dept., Penn State University, University Park PA 16802