Profile-engineered composite long-period gratings for scalable broadband on-chip higher-order mode conversion

Le résumé fourni par la source

We present a scalable higher-order mode-conversion scheme based on profile-engineered composite long-period gratings (PE-CLPGs). By tailoring the transverse refractive-index perturbation profile according to the symmetry and field distribution of the interacting modes, mode-selective coupling is achieved within a unified design framework. Combined with a tapered waveguide, the proposed structure provides efficient modal overlap and broadband phase matching, enabling broadband higher-order mode conversion. As proof-of-concept demonstrations, TM0-to-TM2, TM0-to-TM4, and TM0-to-TM6 mode converters were designed, fabricated, and experimentally characterized. The fabricated devices maintain insertion losses below 1.7 dB and crosstalk below −15 dB over operating bandwidths exceeding 100 nm. Numerical results further show that the proposed framework can be extended to odd-order mode conversion, non-fundamental-input mode conversion, and TE-polarized higher-order mode conversion, demonstrating its applicability to a broad range of mode-conversion scenarios. In particular, 1-dB bandwidths of 235 nm and 250 nm are achieved for TM0-to-TM3 and TM1-to-TM3 conversion, respectively, while TE0-to-TM3 and TE0-to-TM4 converters exhibit 1-dB bandwidths of 320 nm and 260 nm. The results demonstrate that the proposed PE-CLPG framework is not restricted to a specific mode pair, mode order, or polarization state, providing a scalable and fabrication-friendly approach for broadband higher-order mode manipulation in multimode silicon photonic circuits.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.