Mode-locking via delayed orthogonal-polarization reinjection in semiconductor VCSELs

作者：Tao Wang, Yixing Ma, Zhibo Li, Juncheng Huang, Yiheng Li, Z. J. Tu, Yahui Zhang, Gang Xu, S. Barland, Shuiying Xiang, Yue Hao · 发表于：Optics Letters · 年份：2025 · DOI：10.1364/ol.565396 · 被引用次数：4 · 研究领域：Advanced Fiber Laser Technologies、Photonic and Optical Devices、Semiconductor Lasers and Optical Devices

We demonstrate harmonic mode-locking in a semiconductor VCSEL using polarization-controlled delayed feedback. By integrating a rotatable λ /2-plate within an external cavity, we achieve precise control over pulse multiplicity and repetition rates in TE and TM modes. For the TE mode, increasing the λ /2-plate angle ( θ ) transitions the system from disordered quasi-periodic states to stable fundamental (single-pulse) and harmonic dual-pulse mode-locking. Polarization-resolved measurements and cross-correlation analyses reveal coherent pulse alignment at half the cavity roundtrip time, enabled by polarization-mediated nonlinear dynamics. This work establishes cross-polarization feedback as a fundamental mechanism for ultrafast pulse engineering, advancing the understanding of polarization-mediated nonlinear dynamics in laser physics.