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arXiv · 2608.13261

Inverse-Designed High-Q/V Silicon Nitride Photonic Crystal Cavities for Second- and Third-Harmonic Generation

M. Takiguchi·P. Heidt·X. Z. Lim·J. Zöllner·S. Yanagimoto·K. Nakayama·T. Aihara·M. Ono·H. Sumikura·M. Notomi
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Abstract

SiN photonic crystal (PhC) cavities are promising platforms for nonlinear and quantum photonics because of their wide transparency window, CMOS compatibility, and negligible two-photon absorption. However, realizing high-Q/V cavities remains challenging because of the relatively low refractive index of SiN. Here, we employ inverse design to optimize a two-dimensional SiN PhC cavity and experimentally demonstrate a quality factor of approximately 80,000, the highest reported for a near-stoichiometric SiN 2D PhC cavity. Furthermore, both second- and third-harmonic generation are observed from the same cavity, providing experimental evidence of strong optical confinement and large Q/V. Our results establish inverse-designed SiN PhC cavities as a promising platform for nonlinear photonics and future heterogeneous integrated photonic devices.

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M. Takiguchi, P. Heidt, X. Z. Lim, J. Zöllner, S. Yanagimoto, K. Nakayama, T. Aihara, M. Ono, H. Sumikura, M. Notomi. 2026-08-13. Inverse-Designed High-Q/V Silicon Nitride Photonic Crystal Cavities for Second- and Third-Harmonic Generation. https://arxiv.org/abs/2608.13261

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