Compact Silicon Photonic Grating Coupler With Dual-Taper Partial Overlay Spot-Size Converter

Abstract

A compact silicon photonic grating coupler enabling fiber-to-chip light coupling at a minimized footprint is proposed. The proposed coupler, which is partially overlaid at the tapered region, downsizes the effective length of the spot-size converter to 60 μ m while reducing the lateral height and width adiabatically to 220 nm and 320 nm, respectively. The incorporation of such a coupler in a photonic integrated circuit requires a total physical length and width of 75 μ m and 14 μ m, respectively, to enable effective interfacing with single mode fiber. The coupling efficiency and bandwidth of the structure at the light wavelength of 1550 nm are quantified as 68% and 67 nm, respectively, which outperform most recent demonstrations.