Research On Metamaterials Terahertz Absorber

Electromagnetic metamaterial is a new concept in the field of materials design. As an artificially-engineered electromagnetic material with the structure of periodic unit cell array, metamaterial shows abnormal physical properties. It is one of the hotspots of international related fields over the past decade. With the rapid development of electromagnetic metamaterials, its absorbing properties also attract wide attention of researchers.Due to the high absorption, ultra-thin thickness, frequency selective, design flexibility and other advantages, metamaterial absorber in terahertz got much attention. After N.I.Landy proposed the perfect absorber structure firstly, the research of metamaterial absorber also evolved from the pursuit of higher absorption rate of a single frequency to the wide angle and polarization insensitivity.The thesis summarizes the principle and the development of metamaterial absorber. CST Studio Suite 2013 was used to design and calculate the absorber properties in the terahertz band. Firstly, we analysis the absorbing properties based on the square metal, and introduce the surface current on both layer and the E-filed of top layer. Diagonal arrangement of the two defect structure is arranged in a square metamaterial unit structure. The surface current and the E-field distribution analysis are shown in the chapter. The absorbing rate with the wide angle TE and TM waves is also analyzed. The results show that:defect structure defects wit diagonal arrangement can greatly increase the absorption bandwidth.Secondly, based on the coplanar double rings, the surface current of each ring is analyzed to show its absorbing mechanism. The absorbing rate with the wide angle TE and TM waves is also analyzed. This chapter also discusses the influence of energy loss in dielectric layer material. The absorption bandwidth is increased with external ring metal compensation. The results show that:Double ring absorber has a very wide absorption bandwidth. Ohmic losses of the top layer are the major energy losses in the absorber. It is insensitive to the parameters of middle layer. Meatal compensation block can increase the metal absorption bandwidth.