2025/12/12 by Lim, Xuen Zhen, Takiguchi, Masato, Kuruma, Ryuji +2
Engineering · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Metamaterials and Metasurfaces Applications #Optics (physics.optics) #Orbital Angular Momentum in Optics #Plasmonic and Surface Plasmon Research
paper · doi:10.48550/arxiv.2512.11232
openalex publication_date 2025/12/12 · openalex created_date 2025/12/16 · openalex updated_date 2026/07/28
We designed a gallium nitride hexagonal hollow nanowire whispering gallery mode cavity that generates an |m|=6 topological light with orbital angular momentum (OAM). OAM is generated by breaking the cross-sectional mirror symmetry of the nanowire, which creates a non-Hermitian system. This is achieved by replacing the central airhole of the hollow nanowire with a cluster of 6 overlapping circular air holes with rotational offset relative to the hexagonal cross-sectional profile of the nanowire. The design parameters were then further optimized in Finite Element Method using an inverse design method to maximize the normalized OAM order |l|. We were able to realize of a cavity mode with |l| = 5.7, a mode purity of about 97%, and a Q-factor of ~250. This marks the first OAM generating active photonic device design falling within a sub-micron footprint, with additional novelties of being single component and materialistically homogeneous.