Fano-resonant filtering by planar chromium-based multilayer stacks

We demonstrate the design, fabrication, and experimental characterization of planar chromium-based metal-dielectric (Cr-MD) multilayer stacks that support sharp angular and spectral filtering via Fano-type resonances. Two configurations are investigated, differing in the sequence of dielectric layers above a chromium film. Under total internal reflection conditions, hybrid Tamm-waveguide modes yield bright and dark Fano resonances with angular widths of about 0.5 mrad. The high-contrast passband and stopband features are achieved, tunable via Cr thickness. Chromium's unique optical response enables broadband Tamm resonances, providing a compact platform for advanced optical filters. Potential applications include laser spatial mode control, optical sensing, and Raman spectroscopy.