Broadband plasmonic terahertz absorber based on silicon cross structures

A broadband terahertz absorber based on plasmonic cross structure resonators is proposed and investigated. This plasmonic absorber yields above 90% absorbance from 0.67 THz to 1.78 THz in the simulation, compared with 0.74 THz to 1.62 THz in the experiment. The remarkable absorption bandwidth of about 90% in theory can be associated with two plasmonic resonances supported by the cavities bounded by the cross structure. Further, the absorber is polarization-insensitive and can operate over a wide range of incidence angles for both the transverse electric (TE) and transverse magnetic (TM) radiation. This plasmonics approach to terahertz absorption provides a path towards realization of efficient components for bolometric imaging and terahertz communications.