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arXiv · 2512.11232

Inverse-Designed Non-Hermitian Hollow Nanowire Cavity for Generating Optical Orbital Angular Momentum

Xuen Zhen Lim·Masato Takiguchi·Ryuji Kuruma·Hisashi Sumikura·Masaya Notomi
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Abstract

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.

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Xuen Zhen Lim, Masato Takiguchi, Ryuji Kuruma, Hisashi Sumikura, Masaya Notomi. 2025-12-12. Inverse-Designed Non-Hermitian Hollow Nanowire Cavity for Generating Optical Orbital Angular Momentum. https://arxiv.org/abs/2512.11232

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