Metainterface and Application for High-Performance Spectro-Polarimetric Filter

Metasurface attracts much attention but lacks the modulation ability along the beam propagation direction, which confines its ability to control the wavelength and polarization of light. We propose a new concept of metainterface by embedding a two-dimensional metamaterial in a layered structure with vertical control ability. It can hugely improve the light control power and generate excellent characteristics while keeping simple fabrication processes. A high-performance spectro-polarimetric filter, which is based on the interface composed of one-dimensional photonic crystals and 10 nm thick Al grating, is fabricated for demonstration. Experimental results show that it can simultaneously have a polarization extinction ratio (PER) of 800 and a spectral resolution power (SRP, λ/Δλ) of 113, which are, respectively, 74 and 9 times better than the recently obtained best results of the metasurface. Moreover, it can break the limitation of diffraction and achieve much higher PER with limited size gratings. Because of these characteristics, it has great potential in miniature and integrated spectropolarimeters.