RUI: Perturbation-Induced Dynamics and Chaos Synchronization in Multi-Transverse-Mode Vertical-Cavity Surface-Emitting Lasers

垂直腔面发射激光器(VCSEL)广泛应用于光纤通信和互连中，对光反馈和光注入非常敏感。这些扰动可以导致丰富的非线性动力学行为，如频谱展宽、不规则和混沌脉动以及偏振不稳定性。由于垂直腔面发射激光器在偏置电流增大时经常以多个横模工作，因此由于不同横模的空间分布，增加了系统的复杂性。因此，光注入和反馈引起的动力学问题在基础科学和工程应用中都具有重要的研究意义。特别是，光反馈和光注入在两个激光器的混沌同步中都起着关键作用，这对保密数据通信具有重要意义。混沌同步也是耦合时滞系统的一个基本性质。我们从实验上研究了垂直腔面发射激光器的微扰诱导极化和横向动力学。在多横模区域，我们研究了混沌区域的动力学路径，光反馈和电流调制的相互作用，以及两个频率的光注入的影响。所得结果有助于实现两个多模垂直腔面发射激光器的混沌同步，并验证了相应的理论结果。如上所述，垂直腔面发射激光器是研究复杂系统动力学的理想工具，也是一种很有前途的光纤通信设备。我们对多横模垂直腔面发射激光器在微扰作用下的非线性动力学的研究将对研究非线性动力学和激光物理的科学家产生有趣的结果。由于多模垂直腔面发射激光器由于其较低的模式噪声以及混沌同步对于保密数据传输的重要性，因此多模垂直腔面发射激光器已被用于局域网(LAN)中，其结果也将对光纤通信社区有用。该项目通过将研究与本科培训和学习相结合来加强本科教育。学生通过暑期研究、高级论文和独立研究参与到这个项目中来。此外，还在高级课程和实验室中介绍了使用VCSELs的实验和演示。当地高中生和教师可以通过加入研究和参观PI的实验室从该项目中受益。

Widely used in optic-fiber communications and interconnections, vertical-cavity surface-emitting lasers (VCSEL) are sensitive to optical feedback and optical injection. These perturbations can induce rich nonlinear dynamical behaviors, such as spectral broadening, irregular and chaotic pulsations, and polarization instabilities. Since VCSELs often operate with several transverse modes when the bias current goes up, complexity of the system increases due to spatial profiles of different transverse modes. Therefore dynamics induced by optical injection and feedback is a topic of significant research interests for both fundamental science and engineering applications. In particular, both optical feedback and optical injection play key roles in chaos synchronization of two lasers, which is of interest to secure data communications. Chaos synchronization is also a fundamental property of coupled, time-delay systems. We investigate experimentally perturbation-induced polarization and transverse dynamics of VCSELs. In the multi-transverse mode regime, we study dynamical routes to chaotic regime, interplay of optical feedback and current modulation, and effects of optical injection of two frequencies. The obtained results help us to achieve chaos synchronization of two multimode VCSELs and to validate corresponding theoretical results. As described above, a VCSEL is an ideal vehicle for studying dynamic in complex systems and a promising device in fiber-optic communications. Our study on nonlinear dynamics of multi-transverse-mode VCSELs subject to perturbations will produce interesting results for scientists who study nonlinear dynamics and laser physics. The results will also be useful to community of optic-fiber communications because multimode VCSELs have been used in local area network (LAN) due to their lower modal noise and because chaos synchronization is important for secure data transmission. The project enhances undergraduate education by integrating research with undergraduate training and learning. Students are involved in the project through summer research, senior theses, and independent studies. Besides, experiments and demonstrations that utilize VCSELs are introduced in advanced courses and laboratory. Local high school students and teachers can benefit from the project through joining the research and visiting the PI's laboratory.