Departament de Fisica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, 08222 Terrassa, Barcelona, Spain.
Philos Trans A Math Phys Eng Sci. 2013 Aug 19;371(1999):20120471. doi: 10.1098/rsta.2012.0471. Print 2013 Sep 28.
We perform a detailed numerical analysis of square-wave (SW) polarization switching in two semiconductor lasers with time-delayed, orthogonal mutual coupling. An in-depth mapping of the dynamics in the two-parameter plane coupling strength versus frequency detuning shows that stable SWs occur in narrow parameter regions that are localized close to the boundary of stability of the pure-mode solution. In this steady state, the two coupled lasers emit orthogonal polarizations. We also show that there are various types of SW forms and that stable switching does not need the inclusion of noise or nonlinear gain in the model. As these narrow regions of deterministic and stable SWs occur for quite different combinations of parameters, they could potentially explain the waveforms that have been observed experimentally. However, on the other hand, these regions are narrow enough to be in fact considered as experimentally unreachable. Therefore, our results indicate that further experimental statistical studies are needed in order to distinguish deterministic and stationary square waveforms from long transients because of noise.
我们对具有时滞、正交互耦的两个半导体激光器中的方波 (SW) 偏振转换进行了详细的数值分析。在耦合强度与频率失谐的两参数平面中对动力学进行深入映射，结果表明，稳定的 SW 出现在靠近纯模解稳定性边界的狭窄参数区域内。在这种稳定状态下，两个耦合激光器发射正交偏振。我们还表明，存在各种类型的 SW 形式，并且在模型中不需要包含噪声或非线性增益即可实现稳定切换。由于这些确定且稳定的 SW 的狭窄区域适用于非常不同的参数组合，因此它们可能可以解释实验中观察到的波形。然而，另一方面，这些区域足够窄，实际上可以认为在实验上是无法达到的。因此，我们的结果表明，需要进一步进行实验统计研究，以便将由于噪声引起的确定性和稳定的方波与长暂态区分开来。
