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Chapter
Ultrafast THz Spectroscopy of Excitons in Multi-Component Carrier Gases
We discuss time-resolved experiments that study photo-excited e-h pairs in GaAs quantum wells via their THz response. Resonant generation of excitons leads to characteristic THz spectra dominated by 1s-2p intra-e...
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Chapter and Conference Paper
Stimulated Terahertz Emission from Excitons in Cu2O
Using ultrashort terahertz (THz) pulses we observe stimulated emission between internal energy levels of excitons. Emission occurs in Cu2O due to the 3p to 2s transition at 6.6 meV, with a cross section of 10−14 ...
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Article
Ultrafast terahertz probes of transient conducting and insulating phases in an electron–hole gas
Many-body systems in nature exhibit complexity and self-organization arising from seemingly simple laws. For example, the long-range Coulomb interaction between electrical charges has a simple form, yet is res...
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Article
Macroscopically ordered state in an exciton system
There is a rich variety of quantum liquids—such as superconductors, liquid helium and atom Bose–Einstein condensates—that exhibit macroscopic coherence in the form of ordered arrays of vortices1,2,3,4. Experiment...
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Article
Towards Bose–Einstein condensation of excitons in potential traps
An exciton is an electron–hole bound pair in a semiconductor. In the low-density limit, it is a composite Bose quasi-particle, akin to the hydrogen atom1. Just as in dilute atomic gases2,3, reducing the temperatu...
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Article
Many-body and correlation effects in semiconductors
Solids consist of 1022–1023 particles per cubic centimetre, interacting through infinite-range Coulomb interactions. The linear response of a solid to a weak external perturbation is well described by the concept...
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Chapter and Conference Paper
Quantum kinetics in semiconductors: Experiments on a 10-femtosecond timescale
In Quantum Kinetics, a few tens of femtoseconds after optical excitation, scattering processes in semiconductors are not completed, thus relaxation has not yet become irreversible. Here we review recent experi...
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Chapter and Conference Paper
Photocarrier Relaxation in the Quantum Kinetics Regime
A study of carrier dynamics in GaAs in the sub-100 fs regime ontradicts Bolzmann Kinetics, and is compared with a Quantum-Kinetic calculation.
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Article
Carrier transport effects and dynamics in multiple quantum well optical amplifiers
The gain recovery dynamics of multiple quantum well semiconductor optical amplifiers, following gain compression caused by ultrashort optical pulse excitation, have been studied for several devices of differen...
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Chapter
Amplitude Decay and Instantaneous Frequency Dynamics of Excitonic Polarization in Semiconductor Quantum Wells
Coherent light scattering is an ideal tool to investigate the microscopic interactions that take place in various diluted or condensed phase systems1. It is of particular interest in semiconductors where the Coul...
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Chapter
Ultrafast Time-Resolved Spectroscopy of Quantum Confined Semiconductor Heterostructures
We review recent investigations of ultrafast dynamics of electronic excitations in quantum confined semiconductor heterostructures. We concentrate on two topics: the femtosecond time resolved investigations of...
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Article
Optical properties of quasi-zero-dimensional magneto-excitons
We discuss the evolution of optical properties of semiconductor quantum wells, as the quasi-two-dimensional electronic states are further confined into quasi-zero dimensions by a perpendicular magnetic field. ...
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Chapter
Nonlinear Optics and Optoelectronics in Quasi Two Dimensional Semiconductor Structures
In this article we review the most salient results obtained in the 80’s in the fields of nonlinear optics and optoelectronics of semiconductor quantum well structures, with a particular emphasis on the propert...
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Chapter and Conference Paper
Gain Compression and Recovery Dynamics in Multiple Quantum Well Optical Amplifiers
The gain of a multiple quantum well optical amplifier recovers with fast (1 ps, 7ps) and slow (200 – 400 ps) components subsequent to gain compression by an intense pump pulse. The 7 ps time constant is caused...
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Chapter and Conference Paper
Electrorefractive Waveguide Devices Using Tunable Electron Density Quantum Wells
We demonstrate a novel tunable-electron-density electrorefractive multiple-quantum-well waveguide with high speed capability. 5.4 V produces 180° phase shift in a 650 μm long device.
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Chapter and Conference Paper
Femtosecond Spectroscopy of Quasi-Zero-Dimensional Magneto-Excitons
Quantum confinement of electronic states in quantum wells is achieved by layered thin film growth techniques. These materials demonstrate that linear and nonlinear optical properties depend critically on dimen...
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Chapter and Conference Paper
Kilohertz Amplification of Femtosecond Pulses near 1.55 µm, to Microjoule Energies
There is much interest in femtosecond spectroscopy of semiconductor heterostructures in materials such as InGaAs or InAlAs which have a bandgap wavelength near 1.5µm. For a long time, the time resolution of th...
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Chapter and Conference Paper
Femtosecond Excitonic Sampling in Submicron Thickness Coplanar Striplines
Excitonic electroabsorption in thin GaAs-AlGaAs free-standing films is a novel approach to femtosecond optoelectronics in which limits of femtosecond electrical pulse generation, propagation and detection can ...
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Chapter and Conference Paper
On the Lineshape of Time-Resolved Four-Wave Mixing
We study the effect of coherent interaction of polarizations in time-resolved Four-Wave-Mixing. The experimental results on excitons show novel effects. The physical origin of these effects is dicussed using s...
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Chapter
Femtosecond Spectroscopy of Optically Excited Quantum Well Structures
Semiconductor quantum wells (QW) have recently attracted much attention because of their electronic transport and optoelectronic properties[1]. The confinement of photocarriers in layers which thickness, Lz, is s...
