Complete Transmission Through a Two-Dimensional Diffraction Grating

Greg Kriegsmann, NJIT

ABSTRACT: The propagation of a normally incident plane electromagnetic wave through a two-dimensional metallic grating, is modeled and analyzed using S-Matrix theory. The period of the structure $A$ is on the order of the incident wave length $\lambda$, but the height of the channel $H$ separating the grating elements is very small in comparison. Exploiting the small parameter $H/A$ an approximate transmission coefficient is obtained for the grating. For a fixed frequency this coefficient is $O(H/A)$ due to the thinness of the channel. However, near resonant lengths it is $O(1)$. That is, for certain widths the structure is transparent. Similarly, for a fixed length the transmission coefficient has the same resonant features as a function of frequency. This latter feature makes this grating potentially useful as a selective filter.