Perfect subwavelength fishnetlike metamaterial-based film terahertz absorbers

Abstract

We present two different designs of robust, easily manufactured metamaterial-based films of subwavelength thickness capable of full absorption of incident terahertz radiation at certain frequencies. Both designs allow a choice between the total absorption of all polarizations or only one linear polarization while the other polarization is reflected. Even if the films are optimized for normal incidence, the absorption remains greater than 99% for angles up to $\ensuremath{\sim}35\ifmmode^\circ\else\textdegree\fi{}$ in the TE and up to $\ensuremath{\sim}65\ifmmode^\circ\else\textdegree\fi{}$ in the TM case. In the first design, the maximum absorption frequency shifts considerably with angle, and in the second design it is independent of angle.