Analysis of nearly depth-independent transmission of lamellar gratings in zeroth diffraction order in TM polarization

Gratings in the resonance domain typically show strong dependences of the diffraction efficiency on grating parameters, especially on grating period and grating depth. In this paper a grating design in a Littrow mounting is demonstrated, which shows a small influence of grating depth on diffraction efficiency in the zeroth transmitted diffraction order of TM polarization. The effect is investigated by near-field analysis and compared with effective medium theory. No analogous effect could be found for the zeroth transmitted diffraction order of TE polarization.