Ultra-broadband Reflector based on Subwavelength All-dielectric Grating

We report the design an ultra-broadband highly reflective subwavelength grating that covers almost the entire visible region. Results show that high reflectivity above 90% covering 450–700 nm can be achieved, corresponding to Δλ/λ=43%. We also provide intuitive physical insights into the broadband high reflection performance of reflector. We expect that this ultra-thin, ultra-broadband and highly reflective all-dielectric reflector can find applications in hyperspectral imaging based on tunable etalon filters.