Fig. 3

A T/FWHM, B S/FoM, and C Q/LoD of the SPC-GRD as \(\left[\text{Air}*{({PSi}_{1}*{PSi}_{2})}^{N}{({PSi}_{2}*{PSi}_{1})}^{N}*\text{Substrate}\right]\) at \({d}_{1}=100\,{\text{nm}}\), \({d}_{2}=170\,{\text{nm}}\), \({P}_{1}=20 \%\), \({P}_{2}=80 \%\) ,and \({d}_{D}=0\,{\text{nm}}\).