A wide-angle and TE/TM polarization-insensitive terahertz metamaterial near-perfect absorber based on a multi-layer plasmonic structure

A kind of near-perfect metamaterial absorber, made of only Au and Si, has been presented in the terahertz band with extremely high absorptance. A flexible design method is proposed, which could create absorbers with four independent functions as follows. First, selective perfect absorption is achieved at a single frequency, which means the absorptance is more than 99.9% at the required frequency and almost 0% at adjacent frequencies. Second, nearly 100% perfect absorption is realized at more frequencies, which can be changed by simply adjusting the geometric parameters. Third, broadband absorption with a controllable band is gained, and the average absorptance exceeds 99% from 1.2 to 2 THz. Finally, the combination of single-frequency absorption and broadband absorption is accomplished, which greatly expands the application prospects of the proposed absorber. Besides, the absorber exhibits high performance over a wide range of incident angles from 0 degrees to 60 degrees. Meanwhile, it is insensitive to both TE and TM waves. The aforementioned design idea can be extended to other bands.

Automated summary

The novel metamaterial absorber, made of only gold and silicon, exhibits near-perfect absorption in the terahertz band with four independent functions: selective perfect absorption, nearly 100% perfect absorption at multiple frequencies, broadband absorption with controllable band, and a combination of single-frequency absorption and broadband absorption.