Spectral correlation between 2D and 1D guided mode resonant filters

We demonstrate the spectral responses of the guided mode resonant filter (GMRF) with 2D and 1D gratings, aiming to comprehensively investigate the spectral correlation between them under different incident conditions. A second-order effective-medium theory (EMT) is applied to calculate the effective refractive index of the corresponding 1D grating. Results show that the reflectance spectra of the 2D GMRF are considered to be a composition of that in two 1D GMRF structures with vertical grating bar orientation. The physical mechanism behind the spectral correlation is also analyzed in detail in terms of the wave vectors. Results and method shown in this letter provide a means to study new features of 2D GMRF, including the high angular tolerance, polarization-insensitivity under oblique incidence, and wavelength tunability.