Thin and thick cross shaped metal grids

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