Directional reversals and multimode dynamics in semiconductor ring lasers

Abstract

We investigate the dynamics of longitudinal modes in quantum-well semiconductor ring lasers by means of a spatiotemporal traveling-wave model. We report the existence of a multimode instability in such a system that provokes a periodic deterministic directional reversal involving jumps between consecutive longitudinal modes. The switching sequence follows the modal frequencies from blue to red, and every modal jump is accompanied by a reversal of the direction of emission. We characterize and analyze this instability via a bifurcation analysis of the full traveling-wave model as well as by performing a linear stability analysis of the monochromatic solutions.

Time-Domain Traveling-Wave Analysis of the Multimode Dynamics of Quantum Dot Fabry–Perot Lasers

“…In QDs indeed the Fast-LSHB of the carriers in the lasing ground state cannot be washed out by diffusion because carrier diffusion cannot occur in a 0D states [23], [24]. Theoretical works have demonstrated that the carrier gratings originated by the standing wave pattern cause a saturation of the gain at the lasing mode wavelength and this saturation can be modeled as a gain compression factor parameter (also known as ε parameter) [25], [26] [27]. Several experimental works have also reported measurements or evidences of high ε-parameter as a peculiar characteristic of the QD lasers [28]- [30], [31].…”

Wavelength Jumps and Multimode Instabilities in Integrated Master Oscillator Power Amplifiers at 1.5 <inline-formula><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>m: Experiments and Theory

“…(1) and (3)-(5) in a similar way as we did previously [14] and detailed in Appendix A. The threshold analysis lead us to the following eigenvalue equation,…”

“…This TWM has been used in the past for studying similar wavelength jumps that occur in passively mode-locked semiconductor lasers [12], and it naturally includes multilongitudinal mode competition and coupled-cavity effects. We briefly summarize the model, and refer the reader to [11], [13], [14] for the details.…”

“…For these reasons, assessing the properties of the device above threshold requires the numerical integration of the full TWM. In our case this is performed via the numerical algorithm developed in [17], that has already been successfully applied to the study of several semiconductor laser systems [8], [12]- [14] and which allows us to explore the impact that the different device parameters have on the dynamics. The numerical algorithm used to solve the full TWM can be found in [15].…”

“…If the mechanisms of modal drift were all known, the currents where wavelength jumps occur could be determined similarly to [5]. In our case, however, the complex interplay of thermal and carrierinduced mechanisms of modal drift make this task highly complicated, and a linear stability analysis of the full TWM [14] is required in order to address this question.…”