Design of High-Efficiency Fully-Etched Binary Blazed Gratings Nearly Vertical Coupler

A high-efficiency binary blazed grating nearly vertical coupler with fully-etched spacing is proposed, which can be fabricated in one lithography step integrated with other SOI components. For transverse-electric polarized incident light, the coupling efficiencies from a fiber to waveguide are 59.2% at a wavelength of 1550 nm and 76.9% at 1563 nm, respectively. A 3-dB bandwidth of 33 nm from 1546 to 1579 nm is also obtained. The numerical simulation also shows that the tolerances of 19 nm in etched depth and 6.5 in incident angle are achievable.