Demonstration and Fabrication Tolerance Study of a Low-Loss, Ultra-broadband Rapid Adiabatic 3-dB Coupler in a Next-Generation 45 nm Monolithic Electronic-Photonic Platform

We demonstrate a rapid adiabatic coupler (RAC) with 50±1.08% power splitting ratio over 100 nm and insertion loss <0.2 dB at 1290 nm. We measure the device over seven reticles and show low variations in splitting ratio and insertion loss across the wafer.