Tuning asymmetry parameter of Fano resonance of spoof surface plasmons by modes coupling

Abstract

We report a kind of subwavelength, compound hole arrays formed by two nested sub-lattices used to modulate the Fano resonance of spoof surface plasmons (SSPs). Experiments complemented with numerical simulations show that the asymmetry parameter (q) of the Fano line shape can be tuned artificially and continuously: the q value experiences a sign reversal and varies linearly with the variation of hole size. The coupling between different SSP modes of sub-lattices is suggested to be responsible for the tunability of Fano resonance in the compound hole arrays.