Wideband Metamaterial Structure Based On CST Simulation And Its Experimental

Terahertz is a submillimeter wave whose wavelength ranges of 0.03~3mm between infrared and millimeter waves.It has unique properties that many other electromagnetic waves do not possess.At the same time,the terahertz spectrum of the material structure also contains very rich physical and chemical information.These advantages make it have many potential applications in the fields of physics,biochemistry,remote sensing,radar,military,homeland security,medicine,astronomy,communications,aerospace,etc.,which have caused concern from all walks of life at home and abroad.Metamaterials are an emerging artificial composite material that combines different common materials to achieve special physical properties like high absorption in the terahertz band.Converters incorporating terahertz metamaterials and infrared detection technology can utilize the metamaterial structure to absorb terahertz wave energy,convert it to infrared radiation and be detected by infrared detectors,which greatly reduces the cost of the terahertz detector.In this structure,the terahertz absorption metamaterial is the core part.In this paper,a single-wafer metamaterial absorbing structure is designed.It consists of a metal wafer,an intermediate medium,and an underlying metal film.The absorption principle of a single wafer metamaterial is studied,and the formula for calculating the resonant frequency of a single wafer metamaterial is derived and used.The CST software simulation made it possible to achieve a high absorption of 99.9% at 2.52 THz.Combined with the surface current distribution of the metal layer and the distribution of the electric field and magnetic field energy,the characteristics of the metamaterial to absorb the terahertz wave were analyzed.The influence of the single-wafer structure metal material,element size,dielectric thickness,and radius of the wafer on the terahertz response was investigated,and the simulation of the change of the absorption characteristics with the increase of the incident angle in the case of TM and TE waves.It is confirmed that the single-wafer structure which absorbs Terahertz wave has the advantage of polarization insensitivity.This paper also designs a multi-layer wafer and a single-layer multi-disk metamaterial structure based on the stacking and flattening of a single wafer structure,effectively widens the absorption bandwidth of the wafer structure.Through simulation,it was confirmed that the more types of disk radius in the structure,the wider the absorption bandwidth.The current distribution of the metal surface is used to explain the similarities and differences between the absorption principles of the two structures to increase the bandwidth:The stack structure due to the existence of useful current between layers,the coupling between the layers enhances the absorption of electromagnetic waves,and there is an upper limit to the increase of the bandwidth due to the existence of the interference current at the underlying metal film in the tiled structure.Finally,a novel composite wafer stack structure is constructed by combining the two structures,achieving an absorption of more than 80% in range of 4.7 to 7.4 THz(bandwidth 2.7 THz),which not only ensures high absorption but also greatly increases the absorption bandwidth.After reducing the size of the structure,the center frequency of the structure can be made larger.In this paper,a single wafer metamaterial structure was realized by using photolithography technology combined with vacuum evaporation.The metal wafer array was clean and uniform with a radius of about 18 ?m.The specific parameters of each process step were clarified through experiments,and the effects of different steps and parameters of the lithography process on the lithography pattern were highlighted.The response characteristics of the single wafer structure to terahertz waves were tested and analyzed.