2x2 Silicon Photonic 3-dB Adiabatic Coupler with Optimized Taper Curvature

We report a 2x2 3-dB adiabatic coupler with the coupler gap of 400 nm and the taper length of 90 μm. The designed curved taper enables 8-times shorter coupler length than a conventional line ar taper. The fabricated device exhibits 50 ± 2% power splitting ratio over the wavelength range from 1580 nm to 1620 nm.