Low-loss Silicon Dual-mode Waveguide Bend with 900nm Width and 3μm Radius

We present a silicon dual-mode waveguide bend with a width of 900nm and an effective radius of $3\mu \mathrm{m}$, which exhibits low-loss and low-crosstalk characteristics. A self-adapted particle swarm optimization algorithm is developed to design the structure, which can generate the optimal structure with minimal intervention. The device is fabricated using electron beam lithography. The measured insertion losses for TE
0
and TE
1
modes are less than 0.02 dB and 0.09 dB per 90°, respectively, across the entire C band. The measured inter-mode crosstalk is less than -22.4dB per 90°.