Low-loss multimode waveguide crossing based on lithium niobate on insulator

【摘要】 With the increasing demand for optical interconnect communication capacity, waveguide crossings are crucial for highdensity photonic integrated circuits（PICs）, especially for mode-division multiplexing（MDM） systems. However, designing multimode waveguide crossings on anisotropic platforms like lithium niobate on insulator（LNOI） remains challenging due to refractive index anisotropy and the limitations of the traditional waveguide crossing method. Here, we propose and experimentally demonstrate a low-loss multimode waveguide crossing on an X-cut LNOI platform, shaped by B-spline curves to support TE₀, TE₁, and TE₂ modes. By independently optimizing Y-and Z-propagation paths, the structure achieves insertion losses as low as 0.11, 0.22, 0.32 dB（Y-propagation） and 0.19, 0.40, 0.53 dB（Z-propagation） at 1550 nm, with crosstalk below-16 dB over a 100 nm wavelength range. The design offers a practical solution for a multimode structure on anisotropic platforms, paving the way for higher integration density in MDM photonic circuits.更多还原

【Abstract】 With the increasing demand for optical interconnect communication capacity, waveguide crossings are crucial for highdensity photonic integrated circuits（PICs）, especially for mode-division multiplexing（MDM） systems. However, designing multimode waveguide crossings on anisotropic platforms like lithium niobate on insulator（LNOI） remains challenging due to refractive index anisotropy and the limitations of the traditional waveguide crossing method. Here, we propose and experimentally demonstrate a low-loss multimode waveguide crossing on an X-cut LNOI platform, shaped by B-spline curves to support TE₀, TE₁, and TE₂ modes. By independently optimizing Y-and Z-propagation paths, the structure achieves insertion losses as low as 0.11, 0.22, 0.32 dB（Y-propagation） and 0.19, 0.40, 0.53 dB（Z-propagation） at 1550 nm, with crosstalk below-16 dB over a 100 nm wavelength range. The design offers a practical solution for a multimode structure on anisotropic platforms, paving the way for higher integration density in MDM photonic circuits.更多还原