Ultra-Broadband, Compact Arbitrary Ratio Power Splitters Enabled by Adiabatic Sub-Wavelength Grating

An ultra-broadband, compact and CMOS-compatible arbitrary ratio power splitter that is based on a directional coupler is proposed on the silicon-on-insulator (SOI) platform. The proposed device consists of an adiabatic sub-wavelength grating (ASWG) and a conventional directional coupler. The wavelength dependence is greatly reduced by introducing an ASWG in the coupling region of the directional coupler. Simulation results show that our proposed device has an operating bandwidth of 250 nm for arbitrary power splitting ratios, with a transmission power variation of less than 8.5%, covering the wavelength range from 1400 nm to 1650 nm. Meanwhile, the device footprint has been narrowed to less than 46 μm. In addition, the power splitters also exhibit a low excess loss of below 0.24 dB. Our proposed ASWG-assisted power splitters show excellent potential for application in large-scale photonic integrated circuits.