Wide-angle ultrasensitive biosensors based on edge states in heterostructures containing hyperbolic metamaterials

Edge states in photonic heterostructures composed of metal layers and all-dielectric one-dimensional photonic crystals (1DPCs) will shift toward short wavelengths (blueshift) with the increase in the incident angle for both transverses magnetic (TM) and transverse electric (TE) polarizations. However, we achieve redshift edge states for TM polarization and blueshift edge states for TE polarization in heterostructures composed of metal layers and 1DPCs containing layered hyperbolic metamaterials. Owing to the opposite wavelength shift of the edge states for two orthogonal polarizations, the ellipsometric phase will change dramatically around the edge state wavelength in a broad angle range. Based on this wide-angle phase singularity property, we propose a biosensor which can work with high refractive index resolution in a broad angle range.