SPECTRAL FILTERING WITH FINITELY CONDUCTING INDUCTIVE GRIDS

Inductive wire grids with square-shaped holes on a thin finitely condu cting metal screen are examined by rigorous three-dimensional electrom agnetic diffraction theory in the region where the optical wavelength is comparable with the grid period. Spectral transmittance and reflect ance 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-ind ependent short-wavelength pass filters are designed for near-infrared and visible light. The importance of finite conductivity is demonstrat ed, and Al appears to be the best metal in this spectral region. (C) 1 998 Optical Society of America.