Apodized grating coupler using fully-etched nanostructures
Wu Hua1, 2, Li Chong1, Li Zhi-Yong3, Guo Xia1, 4, †,
       

SEM images of the fabricated apodized (a) and uniform (b) grating coupler with nanorectangles, apodized (c) and uniform (d) grating coupler with nanoholes.