Single-layer metallodielectric nanostructures as dual-band midinfrared filters

We report a design and fabrication strategy for creating single-layer metallodielectric nanostructures with dual-band filtering properties at midinfrared wavelengths. Genetic algorithm optimization was used to determine an arrangement of nanometer-scale metal pixels within one unit cell of a two-dimensional periodic array that best satisfied the user-specified filter response and nanofabrication design rule constraints. Infrared transmission and reflection spectra measured on an optimized nanostructure array had two narrow stop bands blueshifted by 0.2μm from the designed center wavelengths of 3.3 and 4.1μm, with transmission attenuation greater than −20dB and reflection attenuation less than −1.5dB in each band. This strategy provides a practical and efficient approach to design metallodielectric nanostructures needed for photonic device applications as well as for future low-loss refractive index engineered metamaterials.