Theoretical study on the far-infrared perfect absorbers with SU8 based multilayered metamaterial structure

A theoretical study on the perfect absorbers working in the far-infrared region with SU8 based multiplelayer metamaterials has been demonstrated. The perfect absorbers consist of periodic array of metal particles,SU8 dielectric spacing layer and a thicker metallic bottom layer. Through the LC model and the finite element numerical simulation methods,we studied the performance of the absorber. With finely tuned parameters,such like the thickness of the SU8 dielectric layers,the periodicity of the metal particles array,and the length of the metal particles, the near perfect absorption up to ~ 100% at the wavelength range between 20 μm to 30 μm for far infrared can be achieved. Based on these results,further design for the double-resonator absorber has been provided. Dual band perfect absorption can be accurately and independently obtained by adjusting the particle size of the upper and the lower metal layers. Moreover,the wavelength of the perfect absorption is also almost independent of the incident angle. These phenomena can be attributed to the multiple reflections between the thick metallic bottom layer and metal particle layers separated by SU8 dielectric layer,which can also be explained using a LC model as the resonant absorption in the metal-dielectric-metal cavities.