Ultra-broadband dual-polarization and arbitrary ratio power splitters based on Bezier curve optimized multimode interference

We propose and demonstrate two types of 1 × 2 power splitters based on multimode interference (MMI), which are ultra-compact, fabrication friendly, and low loss. The contours of MMI and output tapers are optimized with Bezier curves, which can implement arbitrary ratio power splitters (ARPSs) and ultra-broadband dual-polarization power splitters (UDPSs). For ARPSs, the experimental results show that arbitrary power splitting ratios can be obtained with an average excess loss (EL) of 0.17 dB at 1550 nm for fundamental TE polarization. For UDPSs, the experimental results show that the ELs for fundamental TE and TM polarization are less than 0.63 dB and 0.44 dB over a large bandwidth of 415 nm (1260-1675 nm). The footprints of the proposed devices are less than 10 µm × 2.5 µm (without input straight waveguide) with large fabrication tolerance.