In this work I present visually the results of a numerical analysis of the transition between classical High-Contrast Gratings (HCGs) and Monolithic High-Contrast Gratings (MHCGs) and I identify the source of the differences between the scatterless reflection peaks and those that either show strong scattering or do not occur in MHCGs. I show that the key property of MHCGs is the independence of the peak reflectivity wavelength on the substrate refractive index, which results from the modal interference inside the grating and the special form of its impedance/admittance matrix. This form of matrix can be obtained for any wavelength and in almost any material system by tuning the geometrical parameters of the grating—its pitch, fill-factor, and height.
Maciej Dems, Maciej Dems,
"Physical principles of monolithic high-contrast gratings", Proc. SPIE 10113, High Contrast Metastructures VI, 101130C (20 February 2017); doi: 10.1117/12.2250291; https://doi.org/10.1117/12.2250291