Aperture array Fabry–Perot interference filter

We demonstrate effective implementation of the Fabry–Perot interferometer with subwavelength aperture arrays on its two metal mirrors to achieve polarization-independent narrow band-pass filtering. By superimposing of aperture array fundamental resonance transmission with one of the Fabry–Perot interference peaks, the moderate filter insertion loss of −5 dB, narrow band-pass width of 15 μm, and efficient out-of-band rejection within the ∼0.1–3 THz range are reported. The Siemens-star-shaped apertures in arrays play an important role to achieve such polarization independence and small insertion loss.