Compact, broadband, and low-loss silicon photonic arbitrary ratio power splitter using adiabatic taper

The arbitrary ratio power splitter is widely used in photonic integrated circuits (PICs), for signal monitoring, power equalization, signal feedback, and so on. Here we designed a fabrication-tolerant, compact, broadband, and low-loss arbitrary ratio power splitter. The proposed arbitrary ratio power splitter was realized with an adiabatically tapered silicon rib waveguide with 70 nm shallow etches and an Si₃N₄ waveguide. The fabrication analysis confirmed that both of them are robust to fabrication errors. 3D finite-difference time-domain simulations show a very low excess loss (less than 0.02 dB for Si₃N₄ waveguide and 0.05 dB for Si rib waveguide), and a broadband operating wavelength range (100 nm). Good fabrication tolerance and standard critical dimensions make the arbitrary ratio power splitter compatible with the standard fabrication process of commercial silicon photonic foundries.