Design and Simulation of Low-Loss Multimode B-Spline Waveguide Bends Based on Lithium Niobate on Insulator

We design and simulate low-loss multimode B-spline waveguide bends based on lithium niobate on insulator assisted by Equilibrium optimizer. The results show that with a bending radius of
$\boldsymbol{30 \mu \mathrm{m}}$
and a wavelength of 1550 nm, the bending losses of the proposed waveguide bend decrease from 2.2442 dB/90°(TE0), 20.6442 dB/90°(TE1), and 13.4473 dB/90° (TE2) to 0.2643 dB/900(TE0), 7.3521 dB/90°(TEI), and 4.8785 dB/90° (TE2), respectively. The results also show favorable crosstalk properties.