Dependence of Transmission Through Subwavelength Linear Apertures on Grating/Aperture Separation*

Far-field transmission spectra were obtained for structures consisting of subwavelength linear apertures flanked on one or both sides by periodic grating arrays in Au films. In each set of structures, the distance from the grating arrays to the aperture was incrementally varied. Transmission spectra clearly showed enhancement and suppression relative to an isolated aperture. A systematic shift in these extremes was observed with varying cavity width while holding other structural parameters constant. Distinct bands of enhancement and suppression arise from this analysis, consistent with a predictive analytical model. Our conclusions allow for precise control over enhancement/suppression at specific wavelengths in future structures.