Thin and thick cross shaped metal grids

Thin cross shaped metal grids have been studied in the infrared for wavelen gths smaller and larger than the periodicity constant. Resonance frequencie s of thin grids, calculated using rigorous computational methods, agree wel l with experimental data and empirical formulas. Resonance wavelength and t he Wood anomaly of metal meshes on silicon substrates show frequency shifts to longer wavelength, with shifts smaller than the refractive index for th e resonance and equal to the refractive index for the Wood anomaly. An empi rical formula for the wavelength of the "thickness" peak of free standing t hick cross shaped grids is shown and agrees very well with experimental and computational results. (C) 1999 Elsevier Science B.V. All rights reserved.