A scheme for increasing the sensitivity of metal–insulator–metal perfect absorber sensors

Abstract

Perfect absorbers have attracted lots of attentions in recent years due to their diverse applications in various fields. Between all designs introduced so far to represent the perfect absorption characteristic, metal–insulator–metal (MIM) plasmonic and metamaterial structures have a reputable standing because of their resonant nature, relatively easy fabrication procedure, and high absorption coefficients. In this paper, we introduce a novel MIM plasmonic structure operating at optical wavelengths that represents high absorption rates of 99.1 and 99.7 percent at two different resonant wavelengths. By extensively investigating the theoretical physics behind this resonant perfect absorptive behavior and inspired by that physics, we invent a new scheme through which sensing capabilities of the structure are noticeably enhanced. It is very likely that the procedure followed in this paper can be applied to similar MIM perfect absorber sensors as well to effectively increase their sensitivities.