Abstract: Aiming at solving the problem that metamaterial absorbing device could only achieve perfect absorption of single frequency or narrow frequency band due to micromachining technology and response characteristics of the device, a new type of metamaterial terahertz broadband absorbing device was proposed. The method of combining two different surface metal structures (e.g. cross structure and resonant ring structure) was proposed to expand the absorption band width. Absorption at the resonance frequency was improved and the advantages of insensitive polarization mode and incident angle were proposed. Numerical simulation and analysis of the absorbing performance of the device was conducted in the work. The working mechanism of the absorber was analyzed. The influence of polarization mode, incident angle, structure size and other parameters on the performance of the absorber was investigated. The simulation results indicate that the absorptivity of the absorber is over 99% in the range of 1.26 THz~1.33 THz, and over 90% in the range of 1.23 THz~1.37 THz. Comparing with other broadband absorbers, the bandwidth of both absorption rate and absorption band is effectively improved.

Key words: terahertz absorbing device; surface metal structure; metamaterial; resonance frequency; polarization mode