Ultra-broadband on-chip power splitters for arbitrary ratios on silicon-on-insulator.

We propose and demonstrate on-chip power splitters based on adiabatic rib waveguide enabling arbitrary splitting ratios on a monolithic silicon photonic platform. The devices are elaborately engineered based on adiabatic directional couplers with a trapezoid-structure in the longitudinal direction in the mode evolution region. The measurement results indicate that the proposed devices can achieve over 150 nm bandwidth for arbitrary splitting ratios of 50%:50%, 70%:30% and 90%:10%. The mode evolution footprint is greatly narrowed to below 79 µm with an insertion loss of less than 0.22 dB. The demonstrated arbitrary ratio power splitters offer a promising application prospect in high-density photonic integrated circuits.