2025/04/16 by Ting Wang, Yingjie Ma, Wang, T. +17 · 1 citation
Engineering · #FOS: Physical sciences #Molecular Junctions and Nanostructures #Optics (physics.optics) #Photonic and Optical Devices #Semiconductor Lasers and Optical Devices
paper · pdf · doi:10.48550/arxiv.2504.11965
openalex publication_date 2025/04/16 · openalex created_date 2025/10/19 · openalex updated_date 2026/07/28
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.