Multi-longitudinal-mode dynamics in twin-stripe lasers

Simulations for two laterally coupled Fabry-Perot type semiconductor lasers are presented. We show a threshold reduction effect and synchronization of the longitudinal modes in case of asymmetric pumping. For symmetric pumping 50% above threshold we find chaotic oscillations with frequencies well exceeding the single-stripe relaxation oscillation frequencies

Carrier inversion noise has important influence on the dynamics of a semiconductor laser

We find that, although inversion noise has only a marginal effect on the linewidth of a semiconductor laser in continuous wave operation, in the presence of dynamics, it may play an important role in determining the final dynamical state. It is, therefore, essential to include realistic carrier noise when analysing semiconductor laser dynamics

Dynamics of laterally coupled semiconductor lasers: transition to chaos

A method for the investigation of the dynamics of two semiconductor lasers, grown side-by-side on the same wafer to enhance the lateral optical coupling, is presented. Using steady state analysis, parameter regimes of relevant dynamics are identified. This is completed by a spectral analysis, were two routes to chaos are implicated. Finally, we confirm the calculations by showing an avoided crossing type of behavior for the coupling strength

The influence of noise on the dynamics of semiconductor lasers

We find that, although inversion noise has only a marginal effect on the linewidth of a semiconductor laser in CW operation, in the presence of dynamics it may play a key role in determining the final dynamical state. It is therefore essential to include both field noise and carrier noise of realistic strength when analysing semiconductor laser dynamics. Next we investigate the influence of quantum noise, both field and carrier noise, on the highly complex nonlinear dynamics that arise in a single-mode semiconductor laser subject to filtered optical feedback. Our numerical study based on stochastic rate equations shows that for a wide range of filter widths the noise may lead to qualitatively different dynamics than predicted by a deterministic analysis. In particular, we find that certain attractors that are predicted in the absence of noise may no longer be available when the effects of noise are correctly incorporated, while others show remarkable robustness instead. In general, the results confirm that carrier noise in the laser can influence the dynamics quite substantially. Finally, we present numerical results of noise-induced pulsations in a semiconductor laser with optical injection. We show that, close to the locking edge, patterns of single, two and three pulses can be excited and we suggest that experimental study of this multi-pulse excitability be based on pulse timing statistics

Global bistability in a semiconductor laser with filtered optical feedback

Through simulations based on the rate equations for a diode laser with filtered external optical feedback, we show that the laser's dynamical system attractors can be controlled through the filter parameters: the filter's spectral width and its central frequency. This is illustrated for a filter-induced global bistability

Dynamics in the frequency of a semiconductor laser using feedback from a narrow filter

We demonstrate that by spectrally filtering the delayed optical feedback into a semiconductor laser, one can elicit novel dynamics in the frequency of the laser output light on a time scale that is set by the delay time of the feedback

Experimental and theoretical study of semiconductor laser dynamics due to filtered optical feedback

We report experimental results on the nonlinear dynamical response of a semiconductor laser subjected to time-delayed (>5 ns), frequency selective, optical feedback from a Fabry-Pe´rot interferometer type of filter. Three regimes of interest, based on the relative value of the filter bandwidth with respect to the relevant laser parameters (relaxation oscillation frequency and external cavity mode spacing), are identified, viz. a wide filter case, an intermediate filter width case, and a narrow filter case. The dynamical response of the laser is shown to be quite different in each of these regimes. The principal results are 1) the laser's linewidth enhancement factor, coupled with the nonlinear response of the filter, can be exploited to induce nonlinear dynamics in the instantaneous optical frequency of the laser light on a time scale related to the time-delay of the feedback, 2) a mode mismatch effect which arises from a detuning between the filter center frequency and the nearest external cavity mode and manifests itself in a reduction of the maximum light available for feedback, and 3) a reduction in, or even disappearance of, relaxation oscillations in the laser dynamics when a filter of appropriate width is chosen. More generally, it is observed that certain dynamics that occur due to unfiltered optical feedback may be suppressed when the feedback light is spectrally filtered

Inversion dependent non-linear coupling in laterally coupled semiconductor lasers

The study of coupled semiconductor lasers is gaining in popularity, both due to the drive towards integrated optical components, but also due to the large variety of dynamics that coupled lasers can exhibit [1]. Since the integration of optoelectronic devices requires the placement of multiple components on a single chip, these components are generally, intentionally or unintentionally, coupled to some degree and therefore the underlying physics of coupled semiconductor lasers is of great interest also for integration technology. Here, we will present the simulation of two laterally coupled Fabry-Perot type semiconductor lasers, separated by about 4 µm, the so-called twin-stripe lasers. For an in-depth analysis of these devices we refer to [2]. We will investigate the effects on the dynamics of an inversion dependant coupling between the lasers. It has earlier been shown that two main mechanisms for coupling exist for coupling of the field in twin-stripe lasers: coherent coupling of the optical fields and incoherent coupling, where the gain of one laser contributes with stimulated emission photons to the field of the neighboring lasers [3]. Our emphasis will be on the coherent type of coupling. In a rate-equations type of description the coupling strength between the two laser stripes is quantified by the coupling rate. So far, it was assumed that this coupling is constant and independent of the carrier fluctuations in each stripe. However, recent theoretical work, using coupled wave-guide theory has shown that the inversion dynamics will cause the coupling rate to fluctuate and alter the coupling strength. In the next section we present a short overview of the underlying theory and the simulation conditions, followed by presentation of the results. We will end with some concluding remarks

Dynamics-induced asymmetries in the nonlinear gain of semiconductor lasers on multimode operation

In this paper, we show how the "Bogatov effect" can be included in a robust way into a multimode rate equations model that takes account of multi-wave mixing effects through dynamical gratings burned in the carrier distribution. We reveal how this dynamics might induce changes in the shape of the gain curve which ultimately manifests itself as operation of the laser on modes that do not correspond to the maximum of the gain curve. We also discuss the crucial role played by the carrier diffusion and introduce an intuitive visual approach to identify the phase-matching conditions that lead to the Bogatov effect. This information may be used to identify and interpret any eventual carrier dynamics induced bifurcation in the spectrum of the multimode laser

Filtered optical feedback induced dynamics in semiconductor lasers

\u3cp\u3eAn experimental and numerical demonstration of filtered optical feedback (FOF) induced frequency dynamics in semiconductor lasers were discussed. A filter introduces a controllable nonlinearity in the feedback system, and its influence on the laser dynamics can be manipulated via the filter's bandwidth, and its detuning from the laser frequency. It was also demonstrated that by spectral filtering of the delayed optical feedback into a diode laser it is possible to induce controlled oscillations in the instantaneous frequency of light from laser by careful choice of the filter bandwidth qnd DL frequency. The results suggested that the frequency oscillator is a delay induced dynamical device.\u3c/p\u3