Broadband terahertz metamaterial absorber based on coplanar multi-strip resonators

Broadband terahertz metamaterial absorber formed by four different-shaped metallic strips and a dielectric layer on top a metallic ground plane is theoretically demonstrated. The combination of the four metallic strips structure gives rise to an absorption bandwidth of 0.63 THz with absorption >80%. The FWHM (full width at half maximum) with respect to the central frequency of the absorber can reach 35.2%. Four different-sized metallic strips resonating at different but narrowing separated frequencies provide the ability to achieve the broadband absorption. Moreover, the resonance bandwidth of the metamaterial absorber can be further increased by employing more different-shaped metallic strips. Numerical simulations show that the relative FWHM of the six strips structure can be up to 55.8%, which is greater than that of the four strips absorber. The proposed absorbers have potential applications in many scientific and technological areas, such as THz imaging, detection and sensing.