Optical filter based on a coupled bilayer photonic crystal

We report on the fabrication of an ultra-compact optical filter based on photonic crystal free-standing membranes in bi-layer configuration. The basic heterostructure consists of two 376 nm-thick GaAs-membranes sandwiched between air on a GaAs substrate. The air gap between the two membranes is 520 nm thick. The normal-incidence reflectance measurements and the numerical simulation of reflection spectra show a high sensitivity to the holes diameter