Marc-André Dupertuis

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We report on the direct absorption measurement of the polarization selection rules in a V-groove QWR waveguide. Attenuation measurements in a 1 mm long waveguide were performed from 10 K up to room temperature. These measurements yielded the QWR DOS selection rules for lateral (TE) and vertical (TM) confinement directions. 1D heavy-hole like e(n)h(n) subband features were observed in the TE absorption spectra. Effective mass and 4 x 4 k . p models have been used to evaluate the band to band absorption. For

Efficient deterministic algorithms are proposed with logarithmic step complexities for the generation of entangled GHZ(N) and W-N states useful for quantum networks, and an implementation on the IBM quantum computer up to N = 16 is demonstrated. Improved q ...

We develop a dynamical theory for the optical injection of charge and spin current originating from the interferences between two coherent laser pulses of frequencies omega and 2omega. Multiband Bloch equations which include one- and two-photon interband transitions are derived. They also account for ac Stark shifts and intersubband two-photon transitions. The model is used to describe the case of time-dependent charge and spin current injection in a symmetric GaAs/AlGaAs quantum well. A comparison to the b

The optical properties of high-quality V-groove GaAs/AlxGa1-xAs quantum wires have been investigated using low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) techniques. We systematically study the evolution of PL and PLE spectra as a function of the wire size. This comparison allows us to analyze the modification of one-dimensional subbands with decreasing win thickness. We clarify the influence of surface corrugation and localization effects on PL and PLE spectra and we observe

We developed InGaAsP BRAQWET (barrier, reservoir, and quantum-well electron transfer) structures using numerical modeling to optimize the band structure. The main improvement was achieved by including i,n,i,p-doped layers in the barrier, thus decoupling the quantum-well (QW) from the electric field in the barrier, The optimized structures show increased QW movement with applied bias, QW level close to the Fermi level at zero bias, low leakage current and low sensitivity to fabrication tolerances, such as la

The electronic states in the conduction and valence bands of quantum wires are studied by means of the effective mass hamiltonian and the Luttinger hamiltonian. The band mixing effects due to the wire geometry are fully taken into account by an accurate finite element solution of the resulting Schrodinger equations. The quantum wire profiles measured by transmission electron microscopy are used. The comparison of theoretical results with photoluminescence excitation spectra of various nanostructures yields

The photoluminescence (PL) and PL-excitation (PLE) spectra of InyCa1-yAs/AlxGa1-xAs compressively strained V-groove quantum wires (QWR's) are compared to that of lattice-matched GaAs/AlyGa1-xAs QWR's with the same wire geometry. The PL is preferentially polarized along the QWR axis and the PL anisotropy increases with increasing indium content y. The observed PLE anisotropy also increases with y at the ground subband transition but is nearly independent of excited subband indices, unlike the case of lattice

The longitudinal spatial hole burning (LSHB) in gain-clamped semiconductor optical amplifiers (GCSOA's) is investigated by means of a numerical model, which is based on position-dependent rate equations for the carrier density and the propagation equations for the optical power, The simulation results show that the carrier densities are nonuniformly distributed within the active layer of GCSOA's, The nonuniformity can be large, especially for high currents and optical signal powers near the saturation. It i

Measurements of spontaneous emission from InGaAsP semiconductor optical amplifiers provide information on both the carrier density and temperature. By spatially resolving the light emitted along the active layer of the device, we find evidence of longitudinal spatial hole burning which results from amplified spontaneous emission in the structure and is modified by the injected optical signal. Under injection, we also observe pronounced asymmetry of the amplified spontaneous emission intensity from the two f

The role of the confinement potential symmetry on the electronic and optical properties of quantum mires is systematically studied. In a wide class of quantum mires with mirror symmetry we evidence a new set of optical transitions resulting both from band mixing and Ct, symmetry breaking at zone center. Several kinds of quasi-one-dimensional excitons are predicted as well as their specific dipole coupling. Even for ultralow C-1 symmetry we find independent excitons with distinct polarization selection rules

We report thermally stable latched operation of a nonlinear Fabry-Perot device without heat sinking other than through the 0.5-mm GaAs substrate. The device has a 2-μm GaAs spacer and integrated dielectric mirrors with reflectivities of 91% and 99%. Operated in reflection at a wavelength of 886 nm, thresholds as low as 1 mW, and contrast ratios of 10:1 have been observed. Measurements of the threshold dependence on the size of the excited spot give evidence for carrier diffusion and light-diffraction effect

Experimental demonstration of optical speedup at transparency (OSAT) has been performed on a 1 mm long semiconductor optical amplifiers (SOA). OSAT is a recently proposed scheme that decreases the recovery time of an SOA while maintaining the available gain. It is achieved by externally injecting into the SOA the beam of a separate high power laser at energies around the transparency point. Even though the experimental conditions were not optimal, a beam of 100 mW decreases the recovery time by a third when

We report on carrier-induced effects on emission and absorption in forward biased GaAs/AlGaAs V-groove quantum wire (QWR) diodes observed using low-temperature (10 K) photoluminescence (PL), electroluminescence (EL) and PL excitation (PLE) spectroscopy. In the case of simultaneous electron-hole injection we observe a band-gap renormalization (BGR) of at least 5 meV for a carrier density of approximate to 10(6) cm(-1), by comparing high-density EL spectra with low-density PLE spectra. In the case of electron

Quantum many-body states of up to four excitons are studied in small parallelepipedal quantum dots with only two nondegenerate electronic levels in the conduction and in the valence bands. Only one type of hole is considered. We find the set of good quantum numbers (including spin variables for the electrons and holes) which block-diagonalizes the Coulomb and the optical dipole interactions. This provides a convenient labeling scheme for the excited states which allows us to diagonalize nearly entirely anal

An optical device for amplifying or emitting an optical beam of given wavelength comprises an optical source (20) in combination with a primary optical device (10) which is a semiconductor optical amplifier (SOA), a gain-clamped semiconductor optical ampli ...

We analyze the magnitude of degenerate two-photon gain of several quantum wells (QWs) in a resonant microcavity which is pumped off-resonantly by an optical field. A set of coupled phenomenological rate equations for electron-hole pairs and photons is derived. In the framework of this model, we make a realistic prediction of the time-integrated two-photon gain and find that a lambda-cavity containing 11 QWs would give a maximal amplification of similar to 2.3% for a peak,intensity of similar to 80 MW/cm(2).

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 fluctuat ...

We show that the two-dimensional quantum confined Stark effect in a semiconductor quantum wire can display novel behaviour, i.e. wave function splitting and cascading. No analog to these phenomena can be found in bulk material or quantum wells. The consequences of these effects on Stark shifts, oscillator strengths and electroabsorption spectra are explored numerically using k.p theory. A non-trivial prediction of our model is that, for the case of hole wave function splitting, the cascading of the ladder o

Pump and probe measurements with femtosecond resolution are performed on a gain-clamped semiconductor optical amplifier, a structure that contains a lasing mode. The corresponding relaxation oscillations are observed in the temporal gain recovery of the amplifier. The current dependence of the oscillations is well reproduced by a small-signal analysis of the laser rate equations. The gain recovery can be very fast, we measure damping rates of up to 40 GHz.

We present a general theory for semiconductor polarons in the framework of the Frohlich interaction between electrons and phonons. The latter is investigated using noncommuting phonon creation/annihilation operators associated with a natural set of nonorth ...

Marc-André Dupertuis

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Direct observation of new transitions in the absorption spectra of a V-groove quantum wire waveguide

Efficient Quantum Algorithms for GHZ and W States, and Implementation on the IBM Quantum Computer

Dynamics of optical injection of charge and spin currents in quantum wells

Effect of lateral confinement on valence-band mixing and polarization anisotropy in quantum wires

Optimized Band-Structure Design of Ingaasp Braqwet Structures

Band-mixing and coupling in single and double quantum wire structures

Separation of strain and quantum-confinement effects in the optical spectra of quantum wires

Longitudinal spatial hole burning and associated nonlinear gain in gain-clamped semiconductor optical amplifiers

Direct observation of longitudinal spatial hole burning in semiconductor optical amplifiers with injection

The impact of low symmetry on the electronic and optical properties of quantum wires

Thermally Stable Operation of a Bistable Fabry-Perot Etalon with a Bulk Gaas Spacer

Optical speedup at transparency of the gain recovery in semiconductor optical amplifiers

Carrier-induced effects on absorption and emission in V-groove quantum wire diodes

Quantum Many-Body States of Excitons in a Small Quantum-Dot

An integrated holding-beam-at-transparency (hbat) configuration for semiconductor optical amplification or emission

Feasibility study for degenerate-two-photon gain in a semiconductor microcavity

Charged excitons in modulation-doped quantum wires

Quantum confined Stark effect in quantum wires: Wave function splitting and cascading

Time-resolved relaxation oscillations in gain-clamped semiconductor optical amplifiers by pump and probe measurements

Nonorthogonal theory of polarons and application to pyramidal quantum dots