Plasmonic metafiber for all‐fiber <i>Q</i> ‐switched cylindrical vector lasers
Hua He, Chao Zeng, Zhiwen He, Hua Lü, Yueqing Du, Dong Mao, Jianlin Zhao
Abstract
Abstract Metafibers, by integrating metasurface at the optical fiber tip, are emerging as the significant optical coupling platforms for nanophotonics and fiber‐optic communities. Here, we propose a plasmonic metafiber for converting the fundamental mode to first‐order mode in fiber, and as proof of device performance, demonstrate an all‐fiber Q ‐switched cylindrical vector laser using the metafiber. Based on polarization‐dependent plasmonic resonance, a polarization‐independent mode conversion metasurface is designed theoretically and numerically, fabricated directly on fiber facet, and packaged as an all‐fiber component with efficiency up to 21% at 1550‐nm band. Using the metafiber in an all‐fiber laser, Q ‐switched azimuthally polarized beam (APB) and radially polarized beam (RPB) are delivered at wavelength of 1548.5 nm with pulse durations from ∼7 to ∼2 μs when pump power increases from 30 to 120 mW. The mode purities of the APB and RPB are 86.5% and 90.7%, respectively. This work outlines a new strategy to integrate metasurfaces into “all‐in‐fiber” systems and offers a reliable route to construct next‐generation laser sources, such as all‐fiber ultrafast structured lasers.