InGaAs-GaAs quantum-dot lasers

Bimberg, D.; Kirstaedter, N.; Ledentsov, N. N.; Alfërov, Zh. I.; Kop’ev, P. S.; Ustinov, V. M.

doi:10.1109/2944.605656

Cited by 548 publications

(214 citation statements)

References 34 publications

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“…1,2 In this growth process, the strain, due to the lattice mismatch between the deposited material and the substrate, controls to a large extent the formation of self-assembled QDs. The three dimensional confinement of carriers in these nanostructures makes them interesting for applications like QD lasers, 3 single photon sources, 4 and single electron transistors. 5 The optoelectronic properties of QDs are determined by the confinement of the carriers 6 and are therefore directly connected to their morphology, which is the result of a delicate interplay between the elastic relaxation and the surface energy.…”

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confidence: 99%

Height control of self-assembled quantum dots by strain engineering during capping

Grossi

Smereka

Keizer

et al. 2014

Applied Physics Letters

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Strain engineering during the capping of III-V quantum dots has been explored as a means to control the height of strained self-assembled quantum dots. Results of Kinetic Monte Carlo simulations are confronted with cross-sectional Scanning Tunnel Microscopy (STM) measurements performed on InAs quantum dots grown by molecular beam epitaxy. We studied InAs quantum dots that are capped by InxGa(1−x)As layers of different indium compositions. Both from our realistic 3D kinetic Monte Carlo simulations and the X-STM measurements on real samples, a trend in the height of the capped quantum dot is found as a function of the lattice mismatch between the quantum dot material and the capping layer. Results obtained on additional material combinations show a generic role of the elastic energy in the control of the quantum dot morphology by strain engineering during capping.

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mentioning

confidence: 99%

Height control of self-assembled quantum dots by strain engineering during capping

Grossi

Smereka

Keizer

et al. 2014

Applied Physics Letters

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“…(3.51), where for vanishing detuning of the lasing frequency from the atom resonance the imaginary part of the gain is zero. Early studies, however, already showed that the influence of off-resonant optical transitions of the quantum-dot excited states and reservoir states lead to non-vanishing index variations [BIM97a].…”

Section: Charge-carrier-induced Susceptibility In Quantum-dot Lasersmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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In this thesis the dynamics and performance of optoelectronic devices based on semiconductor quantum-dots are investigated.In the first part, the dynamics of quantum-dot lasers under external perturbations is discussed. Using a microscopically based balance equation model that incorporates detailed charge-carrier scattering dynamics and the possibility to describe nonequilibrium between intra-band electronic states, the relaxation oscillations of the quantum-dot laser are investigated. Three qualitatively different dynamic regimes are identified in dependence of the scattering rates -the "constantreservoir" regime for slow scattering, the "overdamped" regime, and the "synchronized" regime for high scattering -characterized by a varying degree of nonequilibrium between the quantum-dot and reservoir states.Important differences to conventional lasers are found in the modulation response and the dynamics in optical injection and feedback setups. Common theoretical models and approaches used to describe these applications are shown to yield inaccurate predictions, especially in the "constant-reservoir" and "overdamped" dynamic regimes. An important consequence is that the amplitude-phase coupling in quantum-dot lasers, commonly described by the α-factor, differs from conventional descriptions due to the desynchronization of gain and refractive index. While the α-factor describes bifurcations of fixed points accurately, it fails in describing dynamic solutions and overestimates the extent of complex dynamics. The observed low sensitivity to optical perturbations in quantum-dot lasers can therefore be attributed partly to the charge-carrier nonequilibrium. Three quantum-dot laser models on different levels of sophistication are presented that can accurately describe the quantum-dot nonequilibrium dynamics.In the second part of the thesis, the performance of quantum-dot semiconductor optical amplifiers is investigated, and two types of applications unique to quantum-dots as active medium are discussed. The ground and excited states of the quantum-dots allow an ultra-broad-band amplification of optical data streams. Amplified signals on the ground-state frequencies are shown to generally exhibit higher quality than on the excited state, due to a lower sensitivity of the groundstate to carrier-density variations. Nevertheless the quantum-dot amplifier is found to allow effective amplification on both frequency ranges. Furthermore, a parameter range is identified that allows for a simultaneous amplification of data signals on the ground and excited state in a counter-propagating setup.The long microscopically polarization dephasing times in quantum-dots are found to enable quantum-coherent interactions on a macroscopic scale at room-temperature. By comparison with experiments, the occurrence of Rabi-oscillations by amplification of ultra-short pulses is demonstrated. Quantum-dot based devices could therefore be used for future applications based on quantum-coherent effects.

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“…The two key features necessary in such devices are high differential gain and fast carrier relaxation into the active states. High differential gain has proved to be present in many QD devices [2], [3] and, recently, ultrafast gain recovery on the scale of 100 fs has been demonstrated [4]. Despite these unique features, the maximum modulation frequency of present day QD lasers at room temperature is only 5-6 GHz [5], which is slower than bulk and QW devices.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast gain recovery and modulation limitations in self-assembled quantum-dot devices

Berg

Bischoff

Magnúsdóttir

et al. 2001

IEEE Photon. Technol. Lett.

220

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. Ultrafast gain recovery and modulation limitations in self-assembled quantum-dot devices. I E E E Photonics Technology Letters, 13(6) Abstract-Measurements of ultrafast gain recovery in self-assembled InAs quantum-dot (QD) amplifiers are explained by a comprehensive numerical model. The QD excited state carriers are found to act as a reservoir for the optically active ground state carriers resulting in an ultrafast gain recovery as long as the excited state is well populated. However, when pulses are injected into the device at high-repetition frequencies, the response of a QD amplifier is found to be limited by the wetting-layer dynamics.Index Terms-Gain recovery, quantum-dot amplifiers, ultrafast.

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InGaAs-GaAs quantum-dot lasers

Cited by 548 publications

References 34 publications

Height control of self-assembled quantum dots by strain engineering during capping

Height control of self-assembled quantum dots by strain engineering during capping

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Ultrafast gain recovery and modulation limitations in self-assembled quantum-dot devices

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