Delay Differential Equation-Based Modeling of Passively Mode-Locked Quantum Dot Lasers Using Measured Gain and Loss Spectra (Postprint) (original) (raw)
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Physics and Simulation of Optoelectronic Devices XX, 2012
In this paper, we investigate the dynamics of a nonlinear delay differential equation model for passive mode-locking in semiconductor lasers, when the delay model is seeded with parameters extracted from the gain and loss spectra of a quantum dot laser. The approach used relies on narrowing the parameter space of the model by constraining the values of most of the model parameters to values extracted from gain and loss measurements at threshold. The impact of the free parameters, namely, the linewidth enhancement factors that are not available from the gain and loss measurements, on the device output is then analyzed using the results of direct integration of the delay model. In addition to predicting experimentally observed trends such as pulse trimming with applied absorber bias, the simulation results offer insight into the range of values of the linewidth enhancement factors in the gain and absorber sections permissible for stable mode-locking near threshold. Further, the simulations show that this range of permissible values is significantly reduced under the application of a bias voltage on the absorber section, thereby suggesting that an applied bias is not only required for pulse trimming, but also a reduction in the linewidth enhancement factor, which is important for telecomm and datacomm applications where such devices are sought as pulsed sources, as well as in military RF photonic applications, where mode-locked diode lasers are used as low noise clocks for sampling.
IEEE Journal of Selected Topics in Quantum Electronics, 2000
A delay differential equation-based model for passive mode locking in semiconductor lasers is shown to offer a powerful and versatile mathematical framework to simulate quantumdot lasers, thereby offering an invaluable theoretical tool to study and comprehend the experimentally observed trends specific to such systems. To this end, mathematical relations are derived to transform physically measured quantities from the gain and loss spectra of the quantum-dot material into input parameters to seed the model. In the process, a novel approach toward extracting the carrier relaxation ratio for the device from the measured spectra, which enables a viable alternative to conventional pump-probe techniques, is presented. The simulation results not only support previously observed experimental results, but also offer invaluable insight into the device output dynamics and pulse characteristics that might not be readily understood using standard techniques such as autocorrelation and frequency-resolved optical gating.
Time-Domain Travelling-Wave Model for Quantum Dot Passively Mode-Locked Lasers
IEEE Journal of Quantum Electronics, 2000
We present a time-domain travelling-wave model for the simulation of passive mode-locking in quantum dot (QD) lasers; accurate expressions for the time varying QD optical susceptibility and the QD spontaneous emission noise source are introduced in the 1-D wave equations and numerically described using a set of infinite-impulse response filters. The inhomogeneous broadening of the density of states of the whole QD ensemble as well as the homogeneous linewidth of each QD interband transition are properly taken into account in the model. Population dynamics in the QD, quantum well, and barrier states under both forward and reverse bias conditions are modeled via proper sets of multi-population rate equations coupled with the field propagation equations. The model is first applied to the study of gain and absorption recovery in a QD semiconductor optical amplifier under both forward and reverse bias conditions. Simulations of passive mode-locking in a two-section QD laser are then performed as a function of the bias parameters. Gain and absorption dynamics leading to the generation of mode-locking pulses is described. The onset of a trailing-edge instability at low currents is observed and fully explained in the framework of the described model. Index Terms-Mode-locked lasers, modeling, quantum dots, semiconductor optical amplifiers.
IEEE Journal of Quantum Electronics, 2000
We present a modified version of the multisection delayed differential equation model, for quantum dot passively mode-locked (ML) lasers when competition between ground state (GS) and excited state (ES) ML takes place. The model takes into account the difference in the group velocity of GS and ES fields. Sole GS, sole ES, and dual-state lasing and ML have been studied. The results are verified with time domain traveling wave simulations and compared, when possible, with experimental results. These tests confirmed the reliability of the model. We found that, in two-section ML lasers, GS lasing and mode locking are always more easily established. For instance, GS lasing can be either self-starting or induced by the initial lasing from the higher energy ES. On the contrary, GS lasing tends to inhibit, to a certain extent, the onset of ES lasing, especially at low injection current and low reverse voltage. Moreover, ES shows less potential to achieve stable ML than GS. Based on these findings, we propose proper theoretical explanation of the achieved lasing and ML regimes in realized devices. Especially, we demonstrate a novel stable dual-state ML regime with remarkable enhanced pulse peak power and pulse width.
Traveling wave modeling, simulation, and analysis of quantum-dot mode-locked semiconductor lasers
SPIE Proceedings, 2010
We analyze the dynamics of a mode-locked quantum-dot edge-emitting semiconductor laser consisting of reversely biased saturable absorber and forward biased amplifying sections. To describe spatial non-uniformity of laser parameters, optical fields and carrier distributions we use the traveling wave model, which takes into account carrier exchange processes between wetting layer and quantum dots. A comprehensive parameter study and an optical mode analysis of operation regimes are presented.
IEEE Journal of Quantum Electronics, 2011
We consider a mode-locked (ML) quantum-dot (QD) edge-emitting semiconductor laser consisting of a reversebiased saturable absorber and a forward-biased amplifying section. To describe the dynamics of this laser, we use the traveling wave model taking into account carrier exchange processes between a reservoir and the QDs. A comprehensive parameter study is presented and an analysis of mode-locking pulse broadening with an increase of injection current is performed. The results of our theoretical analysis are supported by experimental data demonstrating a strong pulse asymmetry in a monolithic two-section QD laser.
Automated analysis of stable operation in two-section quantum dot passively mode locked lasers
2007
In this paper, two-section mode-locked lasers consisting of monolithic quantum dot gain and absorber sections are studied as a function of absorber voltage, injected current to the gain region, and relative section lengths. We map the regions of stable mode-locking as measured by the electrical and optical spectra. A simple algorithm is presented that evaluates the quality of mode locking and allows automated characterization of devices. The relative advantages of increasing the absorber length compared to increasing the absorber reverse bias voltage are analyzed. Initial data indicate that doubling the absorber length from 1.4 to 2.8-mm in a 5 GHz repetition rate device increases the region of stable mode-locking by at least 25%, while increasing the absorber reverse bias can more than double the mode-locking regime. Nonetheless, in these devices, stable mode-locking over greater than a 100 mA bias range is realized with a grounded absorber making single bias control of a passively mode-locked semiconductor laser feasible.
2019
We consider a mode-locked quantum-dot edge-emitting semiconductor laser consisting of a reverse biased saturable absorber and a forward biased amplifying section. To describe the dynamics of this laser we use the traveling wave model taking into account carrier exchange processes between a reservoir and the quantum dots. A comprehensive parameter study is presented and an analysis of mode-locking pulse broadening with an increase of injection current is performed. The results of our theoretical analysis are supported by experimental data demonstrating a strong pulse asymmetry in a monolithic two section quantum dot mode-locked laser
Automated analysis of stable operation in two-section quantum dot passively mode locked lasers
Physics and Simulation of Optoelectronic Devices XV, 2007
In this paper, two-section mode-locked lasers consisting of monolithic quantum dot gain and absorber sections are studied as a function of absorber voltage, injected current to the gain region, and relative section lengths. We map the regions of stable mode-locking as measured by the electrical and optical spectra. A simple algorithm is presented that evaluates the quality of mode locking and allows automated characterization of devices. The relative advantages of increasing the absorber length compared to increasing the absorber reverse bias voltage are analyzed. Initial data indicate that doubling the absorber length from 1.4 to 2.8-mm in a 5 GHz repetition rate device increases the region of stable mode-locking by at least 25%, while increasing the absorber reverse bias can more than double the mode-locking regime. Nonetheless, in these devices, stable mode-locking over greater than a 100 mA bias range is realized with a grounded absorber making single bias control of a passively mode-locked semiconductor laser feasible.