Interferometer Action of a Parallel Pair of Wire Gratings

Abstract

The transmission of electromagnetic waves by a pair of wire gratings is treated as a boundary value problem, including oblique incidence, arbitrary separation between gratings, and ohmic losses. The electric vector is taken parallel to the wires; the wavelength is greater than twice the grating constant and much larger than the wire radius. It is found that, even when the gratings are quite close together, each grating can be regarded as a continuous, partially reflecting surface. On this basis, the band-pass characteristics are described in detail. The relative merits of gratings and thin conducting films are discussed. In a numerical example, it is shown that although the resolving power is the same as with a pair of thin metallic films of the same reflectivity and separation, the calculated peak transmission of the grating is about 8000 times larger.