Tunable angular insensitive mid-infrared transmission filters using GST and the design optimization for electrical switching

Resonant cavity structures integrated with phase change material germanium antimony telluride (GST) function as angular insensitive mid-infrared optical filters. The one-dimensional (1D) sub-wavelength grating structures consisting of GST resonators embedded in metallic (Ag) film act as Fabry-Perot resonators with observable transmission resonances, that can be tuned by thermal excitation when GST switches from amorphous to crystalline state, while maintaining angular insensitivity up to 60 degrees. Modeling and experimental results of an interdigitated design of the 1D resonant structure for reconfigurable applications by electrical switching of the transmission spectra of the optical filter will be presented.