Polarization-Insensitive 1×2 Power Divider on SOI

We report the design of two polarization-insensitive $1 \times 2$ power dividers on SOI with 220nm top silicon. The multimode interference coupler is within 4 $\mu \mathrm{m} \times 140 \mu \mathrm{m}$. For the type I device, the excess losses for both the TE and TM modes at 1550 nm are $\lt 0.1$ dB. For the type II device, the excess losses for the TE and TM modes are $\lt 0.55$ dB over the C band. We also analyze their performance deteriorations due to ±20 nm fabrication errors in width.