Marc-André Dupertuis

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We analyze the role of the confinement potential symmetry on the optical properties of quantum wires in the high-density regime. Within the Hartree-Fock approximation we go beyond a global group-theoretical analysis and analyse the structural details of the symmetrized set of microscopic polarization equations including band-mixing. We show that neglecting conduction band mixing leads to further degeneracies of the quantum wire excitonic fine structure. We also find that the decoupling of the symmetrized po

The results of a group theoretical analysis of the excitonic fine structure are presented and compared with spectroscopic data on single quantum dots. The spectral features reveal the signatures of a symmetry higher than the crystal symmetry (C-3v). A cons ...

We derive the closure relation for N polaritons made of three different types of excitons: bosonized excitons, Frenkel, or Wannier excitons. In the case of polaritons made of Wannier excitons, we show how this closure relation, which appears as nondiagonal ...

The optical nonlinearity of a GaAs/AlAs periodic layered structure was experimentally investigated for the first time. The shift of the reflectivity peak with increasing intensity was observed. A reflectivity contrast of about 10:1 was obtained by varying the incident intensity. Hysteresis loops due to the response delay of both the electronic and the thermal nonlinearity were observed. All-optical logic operations were also demonstrated. A further improvement of the structure may lead to a new type of opti

The conditions of splitting the reflectance, transmittance and absorption spectra of a dispersive symmetric Fabry-Perot microcavity are studied on the basis of classical multibeam interference formula, The special case of a monolithic semiconductor microcavity with quantum well excitons is studied in detail. The problem of resonant splitting of transmittance in the case of a single dispersive quantum well is solved exactly. A useful formalism including generalized time-invariance and well-suited for the ana

We have studied systems of asymmetric coupled GaAs V-groove quantum wires, in which the electrons and holes are injected into different wires. Our experimental results indicate efficient electron and hole tunneling, despite a 7 nm thick AlGaAs tunnel barrier. Temperature dependent electroluminescence exhibit clear effects of tunneling up to room temperature but cannot distinguish electron/hole tunneling from exciton tunneling.

We report on a bulk GaAlAs mirror which is used as a saturable absorber for subpicosecond pulse generation around 835 nm. The mirror consists of a 200 nm layer of bulk GaAlAs (with approximately 5% Al content) which is grown on a linear Bragg mirror and is used as a laser end mirror. The incorporation of the bulk GaAlAs mirror into a synchronously pumped styryl-9 dye laser leads to a significant mode locking improvement and pulse shortening. Optimum operation of the laser is obtained for wavelengths near th

We investigated theoretically the effects of the one-dimensional barriers on the electronic states in a quantum dot grown on a nonplanar substrate. These peculiar barriers drastically modify the confined carrier wave functions and their energies. Connecting the quantum wire to the pyramidal quantum dot leads to an enhancement in the ground to first excited state separation energy and a simultaneous large reduction of the energy size sensitivity. (C) 2004 American Institute of Physics.

We report on the growth of barrier, reservoir and quantum well electron transfer (BRAQWET) structures using chemical beam epitaxy. The photoluminescence spectra of the structures are affected by the bias voltage. The QW emission line is extinguished at positive bias and the barrier emission line is extinguished at negative bias. These effects might be used for the BRAQWETs characterization.

A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, ...

We report on the observation of negatively and positively charged excitons in the photoluminescence spectra of V-groove quantum wires. The charged exciton binding energy increases with the strength of the quantum confinement. We demonstrate that the charged excitons are localized by the fluctuations of the confinement potential and estimate a minimal value of the localization length. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA. Weinheim.

A fractional-dimensional approach is applied to a realistic V-groove quantum wire in order to calculate the excitonic absorption spectrum. An excellent agreement is obtained with much more computationally demanding models as well as with experimental photoluminescence excitation data. However, comparison with a full excitonic calculation reveals situations were the concept of fractional dimensions to some extent fails.

Evidence of tunneling and electronic coupling in a one-dimensional system is reported. This is accomplished by comparing low-temperature photoluminescence and photoluminescence excitation spectra of GaAs double quantum wires of different barrier widths with a full 4 x 4 k . p calculation of coupled interband transitions. [S0163-1829(98)01228-4].

We report on the electric field effects in photoluminescence (PL) and PL excitation (PLE) measurements of reverse-biased GaAs V-groove quantum wires. We observe large redshifts (9 meV at 265 kV/cm) of PL and PLE peaks as well as field dependent intensity and polarization anisotropy variations, which are analyzed by a two-dimensional quantum confined Stark effect model. (C) 1999 American Institute of Physics. [S0003-6951(99)00416-7].

We report the experimental observation of optical bistable switching in a combined distributed-feedback/Fabry-Perot structure. The sample had a high switching contrast with almost zero reflectivity in the on-state. A turnoff time as short as 4 ns was measured. The threshold power for bistability was about 2 mW. Bistable switching with the memory effect and a potential application for all-optical signal regeneration were demonstrated.

We demonstrate an efficient numerical scheme for the computation of the excitonic optical response of actual GaAs/AlGaAs quantum wire structures including a large set of relevant effects; structural, valence band-mixing, dielectric and many-body effects can be accounted for.

Marc-André Dupertuis

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Consequences of low symmetry in quantum wires: Exciton degeneracies and quasi-equilibrium high-density regime

Symmetry Elevation and Symmetry Breaking: Keys to Describe and Explain Excitonic Complexes in Semiconductor Quantum Dots

Closure relations for composite bosons: Difference between polaritons and Wannier or Frenkel excitons

All-Optical Reflectivity Tuning and Logic Gating in a GaAs/AlAs Periodic Layered Structure

Classical analysis of a dispersive symmetric Fabry-Perot microcavity and Rabi splitting in a monolithic semiconductor heterostructure

Electrolummescence of asymmetric coupled GaAs/AlGaAs V-groove quantum wires

Bulk GaAlAs Mirror as a Saturable Absorber for Subpicosecond Pulse Generation around 835 Nm

Effects of the one-dimensional quantum barriers in pyramidal quantum dots

Chemical Beam Epitaxy and Photoluminescence Characteristics of Ingaasp/Inp Braqwet Modulators

Single-photon emission from pyramidal quantum dots: The impact of hole thermalization on photon emission statistics

Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots

Observation of charged excitons in V-groove quantum wires

Fractional-dimensional excitonic absorption theory applied to V-groove quantum wires

Tunneling and coupling between one-dimensional states in double quantum wires

Two-dimensional quantum-confined Stark effect in V-groove quantum wires: Excited state spectroscopy and theory

All-Optical Bistable Switching and Signal Regeneration in a Semiconductor Layered Distributed-Feedback/Fabry-Perot Structure

Computing excitons in V-shaped quantum wires including band-structure and dielectric effects: binding energies and polarization anisotropy of the bright A(1), B-1, A(2) excitons

Alloy Segregation, Quantum Confinement and Carrier Capture in Self-Ordered Pyramidal Quantum Wires

Polarization-Resolved Optical Absorption in Single V-groove Quantum Wires