Broadband silicon grating couplers with high efficiency and a robust design.

A record-high efficiency and bandwidth for a fiber-to-chip grating coupler have been achieved with a robust design and cost-effective fabrication on a silicon-on-insulator platform. The design optimization involves the usual geometrical parameters, period, and fill factor, and a mode matching for the fiber output and grating. The measured coupling efficiency for TE polarization and 1 dB bandwidth are -2.