Grating couplers as optical probe pads in a standard CMOS process

To enable in-line nanophotonic device monitoring, grating couplers for near-vertical wafer-scale optical probing are fabricated in a standard CMOS process. These partially etched “optical probes” demonstrate a robust 3-dB-bandwidth larger than 80 nm allowing for photonic device characterization over the entire C-band throughout the fabrication process.