Analysis of polarization interference-type bpf arrays for nir spectroscopic imaging utilizing all-dielectric planar chiral metamaterials

We investigated the potential application of planar chiral metamaterials (PCMs) to near infrared wavelength filters for multispectral measurement through electromagnetic simulation. PCM assumed here was a two-dimensional sub-wavelength surface grating on a high index film with chiral unit cells. The PCM exhibits optical activity (OA) for normally incident light at a finite wavelength range. Thus, by sandwiching the PCM with a pair of linear polarizers, a polarization interference-type BPF can be constructed. We focused on an all-dielectric PCM consisting of a silicon chiral layer and a dielectric underclad layer on a silica substrate. Wavelength filtering characteristics with different bandwidths have been verified for several underclad materials such as Si₃N₄,Al₂O₃, and Si.