Disorder-averaged excitonic response and its application to normal-mode coupling in semiconductor microcavities within a linear dispersion theory

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We have demonstrated ultrafast coherent control of excitons and exciton-polaritons in semiconductor quantum nanostructures. An InGaAs/AlGaAs multi-quantum-well Bragg structure and an AlGaAs/GaAs crescent-shaped quantum wire structure were used as samples for the control of the exciton-polariton and excitons in the nanostructure. In the multi-quantum-well Bragg sample, a two-stage decay due to the super-radiant exciton-polariton mode is clearly observed under the resonance conditions. Highly sensitive cohere

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

High-efficiency top-emitting InGaAs/AlGaAs microcavity light-emitting diodes (MCLEDs) have been optimized and fabricated. The structures were grown using molecular beam epitaxy on GaAs substrates. They consist of a three-period Be-doped distributed Bragg reflector (DBR) centred at 950 nm wavelength, a cavity containing three InGaAs quantum wells and a 15-period Si-doped DBR. Different values for the wavelength detuning between the spontaneous emission line and Fabry-Perot cavity mode were explored, between

We investigate the mechanisms leading to the optical non-linearities observed on a strongly excited semiconductor microcavity containing quantum wells. This study of a coupled exciton-cavity system is possible owing to the availability of a sample of exceptionally high quality, permitting to exclude effects of disorder and inhomogeneous broadening. Sub-picosecond pump and probe experiments are performed, in the regime of an incoherent exciton gas of high density. For such a gas the dephasing due to collisio

Photoluminescence intensity and emission wavelength of InAsP/InGaAsP and InGaAs/InGaAsP multi-quantum well (MQW) laser structures grown by chemical beam epitaxy (CBE) at 460 degrees C and V/III ratio of 2 are considerably affected by annealing at temperatures 600-650 degrees C which prevents lasing of these structures fused on GaAs substrates. It is shown that the degradation of luminescence characteristics can be decreased by increasing the growth temperature to 480 degrees C and V/III ratio to 4. InAsP/In

The influence of static disorder on the optical properties of microcavity-embedded quantum wells is studied by means of a microscopic model. Both the exciton-photon coupling and the exciton-disorder interaction are treated nonperturbatively. Despite the nonconservation of the in-plane momentum due to disorder, the Rabi splitting is still present. Moreover, the lower polariton is subject to motional narrowing of the spectral response, while for the upper one this effect is less important. This result shows v

We report transient sub-picosecond pump and probe experiments performed on a semiconductor microcavity into which quantum wells have been inserted. The cavity is featuring resonance and strong coupling with the exciton. It is strongly and resonantly excited. Optical amplification of the probe beam (up to a factor of 5) appears, a blueshift of the polaritons occurs once the excitation reaches the exciton saturation density. The intensity of the probe, reflected or transmitted by the sample, oscillates while

We have investigated the optical and structural properties of tensile-strained GaxIn1-xP/InP heterojunctions by cathodoluminescence (CL) in the scanning electron microscope and by transmission electron microscopy (TEM). The lattice mismatch of the samples is ranging from 0.4% (x=5.5%) to 0.84% (x=11.8%). We show, in agreement with previous studies, that the relaxation of tensile-strained epilayers occurs by the emission of partial and perfect dislocations. The numerous twins and stacking faults which are fo

The dye solar cell, is a novel photoelectrochemical solar cell presenting unique advantages, as the use of low cost materials and the potential simplicity of manufacturing. However, a liquid electrolyte is actually required for the transport of the photogenerated positive charges. A major breakthrough is the replacing of the liquid electrolyte by a solid-state hole conducting material – the aim of this work. First, the metal/TiO2 junction was investigated, with either silver or gold as rectifying contact. S

We investigated the optical properties of excitons in quasi-one-dimensional semiconductor quantum structures by photoluminescence and photoluminescence excitation: High-quality GaAs/AlxGa1-xAs heterostructures were grown using low-pressure organometallic chemical vapour deposition (OMCVD) on non-planar substrates. The experimentally observed subband separations are in good agreement with a theoretical calculation of the quantum-confined eigenstates, which includes the mapping of the crescent-shaped wire obt

We examine the correspondence between a quantum system and its classical analogue. We consider the wedge billiard which shows a wide variety of behaviors ranging from integrable to strongly chaotic. Angle-action coordinates are provided for the flow and for the bouncing map when the dynamics is integrable. Special sets of orbits, such as orbits bouncing in the corner and orbits sliding along the boundary are investigated. Their influence on the classical statistical properties is also discussed. At the quan

The optical properties of low pressure metal organic vapor deposition grown GaAs/AlxGa1-xAs (x = 0.5) single quantum well structures (SQW) with grown-in dislocations (GD) were studied by low temperature cathodoluminescence (CL) and photoluminescence (PL). High luminescence efficiency around the GD was observed and attributed to impurity decoration. CL spectra show a region surrounding the GD that consists of Si impurities and native defects in the SQW and barrier layers. The diameter of this region was foun

Disorder-averaged excitonic response and its application to normal-mode coupling in semiconductor microcavities within a linear dispersion theory

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Ultrafast coherent control of excitons and exciton-polaritons in quantum nanostructure

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

Design and characterization of top-emitting microcavity light-emitting diodes

Intrinsic non-linearities in exciton-cavity-coupled systems

Thermal Stability of InP-Based Structures for Wafer Fused Laser Diodes

Microscopic theory of motional narrowing of microcavity polaritons in a disordered potential

Optical stark effect and coherent gain of excitons in a semiconductor microcavity

Transmission electron microscopy and cathodoluminescence of tensile-strained Ga/sub x/In/sub 1-x/P/InP heterostructures. I. Spatial variations of the tensile stress relaxation

Solid state nanocrystalline titanium oxide photovoltaic cells

Optical spectroscopy of semiconductor quantum wires

Classical and quantum mechanics of a chaotic hamiltonian system : the wedge billiard

Cathodoluminescence and Photoluminescence Studies of Dislocations in Gaas/Algaas Quantum-Wells