Arrest of Domain Coarsening via Antiperiodic Regimes in Delay Systems

Motionless domains walls representing heteroclinic temporal or spatial orbits typically exist only for very specific parameters. This report introduces a novel mechanism for stabilizing temporal domain walls away from the Maxwell point opening up new possibilities to encode information in dynamical systems. It is based on anti-periodic regimes in a delayed system close to a bistable situation, leading to a cancellation of the average drift velocity. The results are demonstrated in a normal form model and experimentally in a laser with optical injection and delayed feedback.Comment: 6 pages, 5 figures, resubmitted manuscrip

Nonlinear Dynamics of Semiconductor Lasers and Their Applications

Semiconductor lasers are key components in many optical systems due to their advantages, including their small size, low cost, high efficiency, and low power consumption. It is well-known that semiconductor lasers under external perturbations, such as optical injection, optical feedback, or delayed coupling can exhibit a large variety of complex dynamical behaviors. Nowadays, cutting-edge engineering applications based on the complex dynamics of diode lasers are being conducted in areas, such as optical communications, optical signal processing, encoded communications, neuro-inspired ultra-fast optical computing devices, microwave signal generation, RADAR and LIDAR applications, biomedical imaging, and broadband spectroscopy. The prospects for these applications are even more exciting with the advent of photonic integrated circuits. This Special Issue focuses on theoretical and experimental advances in the nonlinear dynamics of semiconductor lasers subject to different types of external perturbations

Double optical feedback and PT-symmetry breaking induced nonlinear dynamics in semiconductor lasers

A central aim of this research is to probe the nonlinear dynamics that arise in a semiconductor laser due to optical feedback. We investigate two schemes of optical feedback. The first scheme subjects the laser to optical feedback from two external cavities (or two loops), wherein each cavity contains a spectral filter. Using two filtered optical feedbacks, we experimentally demonstrate the ability to elicit and control unique dynamics in the optical emission frequency (wavelength) of the laser. These results are compared to a deterministic model describing the evolution of the complex electric field and carrier density of the laser. As the feedback rate from one cavity is increased, we observe a period doubling route in the frequency dynamics. To determine the influence of quantum noise on the period doubling route, we examine an augmented model of the rate equations which includes the effects of spontaneous emission and shot noise. One of the more surprising results is that in the presence of noise a larger feedback strength is required to induce chaotic dynamics. We find that noise drives the system toward stable attractors and the effects of the time-delay on the periodic dynamics are more pronounced. The second scheme we use is a system consisting of two time-delayed, optically coupled semiconductor lasers. We show that coupled lasers are an excellent test-bed to study parity (P) and time-reversal (T) symmetry breaking. Not only do optically coupled SCLs capture many of the characteristic signatures of PT symmetry breaking, but the time-delay between the lasers introduces novel and surprising features. We develop a simple PT model (analogous to a 2x2 Hamiltonian) that includes the effects of the time-delay. By examining the eigenvalues of the PT model, we can predict the intensity fluctuations by scanning the PT parameter, i.e. the frequency difference between the lasers. We experimentally observe the intensity fluctuations and find excellent agreement with the rate equation model which includes the dynamics of the carrier inversion and optical field

Microwave photonic signal generation in an optically injected discrete mode semiconductor laser

This article belongs to the Special Issue Microwave Photonics Applications.In this paper, microwave photonic signal generation based on the period-one dynamic of optically injected discrete mode (DM) semiconductor lasers has been experimentally demonstrated and numerically simulated. The results show that the frequency of the generated microwave increases linearly with the frequency detuning or optical injection ratio. In addition, a single optical feedback loop is sufficient to reduce the microwave linewidth without significantly deteriorating side mode suppression. The simulation results using a model considering the nonlinear dependencies of the carrier recombination agree well with the experimental results, which indicates that the nonlinear carrier recombination effect is important in determining the nonlinear dynamics of optically injected DM lasers.This research was funded in part by the DESTINI project (2017/COL/007) funded by the ERDF under the SMART Expertise scheme; in part by the DSP Centre (82085) funded by the ERDF through the Welsh Government; and in part by Ministerio de Ciencia e Innovación, Spain, under grant RTI2018-094118-B-C22 MCIN/AEI/FEDER, UE.Peer reviewe

Semiconductor Laser Dynamics

This is a collection of 18 papers, two of which are reviews and seven are invited feature papers, that together form the Photonics Special Issue “Semiconductor Laser Dynamics: Fundamentals and Applications”, published in 2020. This collection is edited by Daan Lenstra, an internationally recognized specialist in the field for 40 years

Mapping bifurcation structure and parameter dependence in quantum dot spin-VCSELs

We consider a modified version of the spin-flip model (SFM) that describes optically pumped quantum dot (QD) spin-polarized vertical-cavity surface-emitting lasers (VCSELs). Maps showing different dynamical regions and those consisting of various key bifurcations are constructed by direct numerical simulations and a numerical path continuation technique, respectively. A comparison between them clarifies the physical mechanism that governs the underlying dynamics as well as routes to chaos in QD spin-VCSELs. Detailed numerical simulations illustrate the role played by the capture rate from wetting layer (WL) to QD ground state, the gain parameter, and the amplitude-phase coupling. By tuning the aforementioned key parameters in turn we show how the dynamical regions evolve as a function of the intensity and polarization of the optical pump, as well as in the plane of the spin relaxation rate and linear birefringence rate, which is of importance in the design of spin lasers promising potential applications. By increasing the capture rate from WL to QD our simulation accurately describes the transition from the QD spin-VCSEL to the quantum well case, in agreement with a previous mathematical derivation, and thus validates the modified SFM equations

Forecasting the chaotic dynamics of external cavity semiconductor lasers

Chaotic time series prediction has been paid intense attention in recent years due to its important applications. Herein, we present a single-node photonic reservoir computing approach to forecasting the chaotic behavior of external cavity semiconductor lasers using only observed data. In the reservoir, we employ a semiconductor laser with delay as the sole nonlinear physical node. By investigating the effect of the reservoir meta-parameters on the prediction performance, we numerically demonstrate that there exists an optimal meta-parameter space for forecasting optical-feedback-induced chaos. Simulation results demonstrate that using our method, the upcoming chaotic time series can be continuously predicted for a time period in excess of 2 ns with a normalized mean squared error lower than 0.1. This proposed method only utilizes simple nonlinear semiconductor lasers and thus offers a hardware-friendly approach for complex chaos prediction. In addition, this work may provide a roadmap for the meta-parameter selection of a delay-based photonic reservoir to obtain optimal prediction performance