Broadband terahertz metamaterial absorber enabled by using high-loss dielectric materials

Abstract

Metamaterial absorbers consisted of two metallic layers separated by low-loss dielectric materials have been extensively presented and studied. However, these absorbers using low-loss dielectric materials usually exhibit narrow bandwidth, which are not conductive to the practical applications. Here, we demonstrate a novel terahertz meta-device that can obviously widen the absorption bandwidth of metamaterial absorber. This meta-device is composed of a high-loss dielectric material sandwiched by a metallic strip and an opaque metallic mirror. Absorption of greater than 80% of the meta-device can cover a continuous frequency range of 2.43 THz, and its relative absorption bandwidth can reach 89.17%. These two indexes are both much larger than those of previous absorption devices using low-loss dielectric materials. Physical mechanism of the meta-device originates from the superposition of two different resonant modes. More importantly, the variation of meta-device parameters can provide considerable degree of freedom to regulate the absorption bandwidth and relative absorption bandwidth of the device