High-Efficiency Unidirectional Dual-Wavelength-Band Grating Coupler With 1D Subwavelength Structure

A unidirectional dual-wavelength-band grating coupler with one-dimensional (1D) subwavelength structures is proposed and experimentally demonstrated. Inverse optimization method is used for the design and the grating coupler fabricated on the silicon-on-insulator chip can achieve efficient fiber-chip coupling simultaneously in the O-band and the L-band. The peak coupling efficiencies in the two bands are measured to be 19.7% and 19.5% with 3-dB bandwidths of 27 and 38-nm, respectively.