Single-etch grating coupler for micrometric silicon rib waveguides.

Grating couplers are widely used as an efficient and versatile fiber-chip coupling structure in nanometric silicon wire waveguides. The implementation of efficient grating couplers in micrometric silicon-on-insulator (SOI) rib waveguides is, however, challenging, since the coupler waveguide region is multimode. Here we experimentally demonstrate grating couplers in 1.5 μm-thick SOI rib waveguides with a coupling efficiency of -2.2 dB and a 3 dB …