High Efficiency and Broadband Two-Dimensional Blazed Grating Coupler With Fully Etched Triangular Holes

A 2-D blazed grating coupler with fully etched triangular holes to realize high efficient and broadband coupling between silicon-on-insulator nanowaveguide and fiber is proposed. By changing the lateral width of a triangular hole along propagating direction in each single grating period gradually according to effective medium theory, a high coupling efficiency of -2.78 dB and an extremely large 1 dB bandwidth of 180 nm are achieved simultaneously. By optimizing the buried oxide thickness from 2 to 1.83 mu m, the coupling efficiency can be further improved to -2.80 dB and 1 dB bandwidth is enlarged to 290 nm.