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We present an experimental and theoretical study of the existence of acoustic phonon sidebands in the emission line of single self-assembled InAs/GaAs quantum dots. Temperature-dependent photoluminescence measurements reveal a deviation from a Lorentzian profile with the appearance of lateral sidebands. We obtain an excellent agreement with calculations done in the framework of the Huang-Rhys formalism. We conclude that the only relevant parameter for the observation of acoustic phonon sidebands is the linewidth of the central zero-phonon line. At high temperature, the quasi-Lorentzian quantum dot line appears to be fully determined by the acoustic phonon sidebands

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We study the ultrafast switching-on and -off of planar GaAs/AlAs microcavities. Up to 0.8% refractive index changes are achieved by optically exciting free carriers at λ = 1720 nm and pulse energy EPump = 1.8±0.18 µJ. The cavity resonance is dynamically tracked by measuring reflectivity versus time delay with tunable laser pulses, and is found to shift by as much as 3.3 linewidths within a few ps. The switching-off occurs with a decay time of ∼ 50 ps. We derive the dynamic behavior of the carrier density, and of the complex refractive index. We propose that our inferred 10 GHz switching rate may be tenfold improved by optimized sample growth.

We report high-resolution spectroscopy by interferometric correlation measurements on the photoluminescence signal of a single quantum dot. We demonstrate that the insertion of a Michelson interferometer in the detection path gives a compact and flexible setup for linewidth measurements. We have used this technique to study self-assembled InAs/GaAs quantum dots. We observe linewidth variations from one quantum dot to another, and we bring evidence of environment effects on the broadening processes. (C) 2002 American Institute of Physics