Numerical Design of a Waveguide Crossing Based on SOI platform for Wideband Photonic Integrated Circuits and Networks

Waveguide crossings are critical components for creating 'overpasses' across photonic nanowires and other complex optical signal processing elements, enabling the construction of integrated photonic circuits on a single chip as well as large-scale integrated photonic neural networks. This paper presents a design proposal for a waveguide crossing based on a pair of perpendicular multimode waveguides using the silicon-on-insulator (SOI) material platform. The central region employs shallow etched depth core waveguides to achieve perfect interference at the intersection point without mode scattering. Numerical simulations indicate that the designed waveguide crossing exhibits very low insertion loss, not exceeding 0.66 dB across the wavelength range from 1550 nm to 1600 nm. Additionally, the device demonstrates minimal insertion losses of 0.025 dB for a height tolerance of Ah = ±10 nm, 0.014 dB for a shallow etched depth tolerance of AhSED = ±20 nm, and 0.12 dB for a width tolerance of ΔW=±100 nm. These excellent performance characteristics position the waveguide crossing as a promising candidate for broad applications in high-end optical signal processing circuits, on-chip photonic networks, and low-loss, wide-bandwidth photonic neural networks.