Inductive wire grids with square-shaped holes on a thin finitely conducting metal screen are examined by rigorous three-dimensional electromagnetic diffraction theory in the region where the optical wavelength is comparable with the grid period. Spectral transmittance and reflectance curves are computed, considering the selection of the metal, the properties of the grid (metal-layer thicknesses, fill factor, aperture shape), and the angle of incidence. High-performance polarization-independent short-wavelength pass filters are designed for near-infrared and visible light. The importance of finite conductivity is demonstrated, and Al appears to be the best metal in this spectral region.
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