In this Letter, we demonstrate experimentally that a patchwork of four metal-insulator-metal patches leads to an unpolarized wideband omnidirectional infrared absorption. Our structure absorbs 70% of the incident light on a 2.5 μm bandwidth at 8.5 μm. It paves the way to the design of wideband efficient plasmonic absorbers in the infrared spectrum.

We present both theoretical and experimental evidence that two metal-insulator-metal plasmonic resonators can be combined into a wideband and total photon absorber in the mid-infrared. We show that, although closely arranged in a subwavelength period, these resonators behave as angularly independent antennas at their own resonant wavelength. The structures thus allow for an efficient dual color photon routing and collection.

We show that a periodic array of metal-insulator-metal resonators can be described as a high refractive index metamaterial. This approach permits to obtain analytically the optical properties of the structure and thus to establish conception rules on the quality factor or on total absorption. Furthermore, we extend this formalism to the combination of two independent resonators.