Compact Low-Loss Dual-Mode Silicon Waveguide Bend with Simple Geometry

A silicon waveguide bend with a width of 900nm and an effective radius of 3µm is proposed, which supports both TE
0
and TE
1
modes while maintaining low insertion loss and crosstalk. An adaptive particle swarm optimization algorithm is proposed for the bend waveguide design, enabling automated generation of optimal structures with minimal human intervention. The device is fabricated using electron beam lithography. The measured insertion losses for TE
0
and TE
1
modes are below 0.02 dB and 0.09 dB/90°, respectively, across the entire C-band. The measured inter-mode crosstalk is below −22.4dB per 90°.