Resonant effects in periodic gratings comprising a finite number of grooves in each period - art. no. 016605

We give numerical evidence of a kind of resonance that appears in infinite perfectly conducting gratings comprising a finite number of grooves in each period when illuminated by a normally incident p-polarized plane wave. Thi s phenomenon is intimately connected with the particular distribution of th e phase of the electromagnetic field inside the cavities, which is automati cally generated by waves of certain resonant wavelengths. The resonances ap pear as sharp peaks in the specularly reflected efficiency and are accompan ied by a significant intensification of the interior field. We study the pa rticular case of rectangular cavities and consider configurations with diff erent numbers of grooves per period. The diffraction problem is solved for s and p polarization by using the modal method, which proves to be especial ly suitable for this profile.