Giant linewidth enhancement factor and purely frequency modulated emission from quantum dot laser

Dagens, B.; Markus, A.; Chen, Jx X.; Provost, J. C.; Make, D.; Gouezigou, O. Le; Landreau, J.; Fiore, Andrea; Thédrez, B.

doi:10.1049/el:20057956

Cited by 88 publications

(55 citation statements)

References 6 publications

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“…. 5 are commonly measured, the measured α-factors in quantum-dot lasers range from near-zero [NEW99a,KON04a,ALE07] to very high values [DAG05], and even "infinite" α [CON07,GRI08a]. Furthermore, a strong dependence on the pump current has been observed [SU05a,JIA12].…”

Section: Amplitude-phase Coupling 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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Section: Amplitude-phase Coupling In Quantum-dot Lasersmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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“…2,3 Recent analysis has shown that the low ground state ͑GS͒ gain saturation of QD devices coupled with a large amount of nonresonant carriers in the QD's excited states ͑ES͒ and barrier states can result in large values above threshold 4 and as a consequence, directly phase modulated devices have been demonstrated. 5 In addition, it has been proposed that the unique carrier dynamics of QD semiconductor optical amplifiers ͑SOAs͒ would lead to a reduction of patterning effects compared to conventional devices, for both linear and nonlinear applications. 6,7 As the understanding of relevant carrier relaxation processes in QD structures improves, additional device functionalities will be realized.…”

mentioning

confidence: 99%

Phase dynamics of InAs∕GaAs quantum dot semiconductor optical amplifiers

O'Driscoll¹,

Piwoński²,

Houlihan³

et al. 2007

Applied Physics Letters

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The gain and phase dynamics of InAs/ GaAs quantum dot amplifiers are studied using single and two-color heterodyne pump probe spectroscopy. The relaxation of the wetting layer carrier density is shown to have a strong effect on the phase dynamics of both ground and excited state transients, while having a much weaker effect on the gain dynamics. In addition, the dynamical alpha factor may also display a constant value after an initial transient. Such behavior is strongly encouraging for reduced pattern effect operation in high speed optical networks. © 2007 American Institute of Physics. ͓DOI: 10.1063/1.2823589͔The physics of quantum dot ͑QD͒ photonic devices has been a subject of great interest since the development of self-assembly growth techniques. One of the principle motivating factors for the study of QD lasers was the possibility of substantially reducing the phase-amplitude coupling ͑␣ factor͒ of semiconductor lasers from values in the region of 3-5 for quantum well devices. 1 Among the expected benefits of such a reduction were low modulation chirp, reduced filamentation in high power devices, and reduced sensitivity to optical feedback. 1 To date, QD lasers have displayed a wide range of ␣ factors, the value displaying a strong dependence on the measurement conditions. 2,3 Recent analysis has shown that the low ground state ͑GS͒ gain saturation of QD devices coupled with a large amount of nonresonant carriers in the QD's excited states ͑ES͒ and barrier states can result in large values above threshold 4 and as a consequence, directly phase modulated devices have been demonstrated. 5 In addition, it has been proposed that the unique carrier dynamics of QD semiconductor optical amplifiers ͑SOAs͒ would lead to a reduction of patterning effects compared to conventional devices, for both linear and nonlinear applications. 6,7 As the understanding of relevant carrier relaxation processes in QD structures improves, additional device functionalities will be realized.Heterodyne pump probe spectroscopy has been established as an ideal tool to directly record the ultrafast gain and refractive index dynamics of SOA devices. Previous studies of the gain and phase dynamics of QD SOAs have been performed by Borri et al., who investigated the effects of carrier heating and spectral hole burning in InAs/ InGaAs QDs, 8 while related techniques have been used to measure the ␣ factor in various conditions. 9 Previously on InAs/ GaAs QDs, we demonstrated the importance of Augermediated carrier capture using a single color pump probe technique 10 and illustrated the effects of ultrafast hole relaxation on the gain recovery 11 using a two-color technique. In this letter, we report on two-color phase measurements of the same structure, and note the presence of a strong phase recovery component at the same time scale as the wetting layer carrier recovery. In addition, we combine these phase measurements with two-color gain measurements to calculate an ␣ factor for the device as a function of pump probe delay. The experimental...

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“…When the control signals A and/or B are fed into the two SOAs they modulate the gain of the SOAs and give rise to the phase modulation of the co-propagating CW signal due to LEF α Agrawal (2001), Agrawal (2002), Newell (1999. LEF values may vary in a large interval from the experimentally measured value of LEF α = 0.1 in InAs QD lasers near the gain saturation regime Newell (1999) up to the giant values of LEF α = 60 recently measured in InAs/InGaAs QD lasers Dagens (2005). However, such limiting cases can be achieved for specific electronic band structure Newell (1999), Dagens (2005), Sun (2004).…”

Section: Theoretical Approachmentioning

confidence: 96%