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，对光反馈和光注入敏感。这些微扰可以引起丰富的非线性动力学行为，如光谱展宽、不规则和混沌脉动以及偏振不稳定性。由于VCSEL通常在偏置电流上升时以几个横模工作，因此由于不同横模的空间分布，系统的复杂性增加。因此，光学注入和反馈引起的动力学是基础科学和工程应用的重要研究课题。特别是，光反馈和光注入在两个激光器的混沌同步中起着关键作用，这对于安全的数据通信是有意义的。混沌同步也是耦合时滞系统的一个基本性质。 我们实验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，我们研究了进入混沌区的动力学途径，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台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，VCSEL是研究复杂系统中的动态的理想工具，也是光纤通信中有前途的设备。 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为研究非线性动力学和激光物理的科学家们带来有趣的结果。由于多模VCSEL具有较低的模式噪声，并且混沌同步对安全数据传输很重要，因此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生培训和学习相结合来加强本科生教育。学生通过暑期研究，高级论文和独立研究参与该项目。此外，利用VCSEL的实验和演示介绍了先进的课程和实验室。当地的高中学生和教师可以通过参加研究和参观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.