Design of a high-efficiency grating coupler with flat-top-like output

What we believe to be a novel high-efficiency grating coupler that can couple out a flat-top-like beam profile is proposed. Theory analyses and simulation results are shown in the design with optimized parameters. The power-up from the optimized grating coupler is over 83.9% (-0.76 dB) at the center wavelength of 1550 nm with the 3 dB bandwidth of about 140 nm. The flat-top area of the output light at a height of 1 mu m above the waveguide surface is about 14 x 14 mu m(2), which is applicable in the illumination field for many optical sensors. (C) 2021 Optica Publishing Group