Single step etched two dimensional grating coupler based on the SOI platform.

We design and demonstrate a single step etched two dimensional grating coupler (2D GC) based on the silicon-on-insulator (SOI) platform using subwavelength cylinders. Taking the lag effect into consideration, the 2D GC is manufactured in the same lithography and etching processes with the strip waveguide. The measured coupling loss of the proposed 2D GC is -6.0 dB, which is comparable with conventional shallowly etched 2D GC, realizing a fabrication simplification without performance degradation.