Research On The Transmission Characteristics And Coherent Control Of Double-layer Chiral Cross Shaped Metamaterial

Due to the unique electromagnetic properties of many natural materials,metamaterials have been paid more and more attention in recent decades and become a research hotspot.More and more attention has been paid to the application of the coherent control of the metamaterials.The coherent control of the metamaterials can dynamically control the intensity of light,the direction of propagation,the angle of polarization,etc.Moreover,coherent control has the characteristics of low energy consumption.However,there are few researches on the coherent control of chiral materials.In my work,I focus on the coherent absorption of double-layer cross-shaped chiral materials.A double-layer chiral cross-shaped metamaterial is designed to achieve the effect of coherent absorption in microwave band,which is verified by experiments,and the structure parameters of metamaterial are changed to achieve the effect of coherent absorption in terahertz band,the circular dichroism of the structure is also studied.The main work is as follows:(1)A double-layer cross-shaped chiral metamaterial structure is designed,which can achieve coherent absorption in microwave band.The single layer of the structure is composed of two vertically intersecting copper strips,the rotation angle between the two layers is 22.5~°.The two layers of copper structure are etched on FR4 by printed circuit board.The transmission,reflection and absorption characteristics of the structure are studied under the incident of a single beam of electromagnetic waves,and the absorption characteristics of the structure under the incident of two coherent electromagnetic waves are studied at fixed frequency of 6.9 GHz,the absorption efficiency of the incident electromagnetic wave can be greatly adjusted and controlled from 0 to 90%,so that the control effect of not absorbing the incident electromagnetic wave can be realized and the coherent perfect absorption can be realized,the result of experiment is the same as that of simulation.In addition,various parameters of the designed material are changed to investigate the influence of various parameters on the coherent absorption.(2)By changing the structural parameters of the designed double-layer cross-shaped metamaterial,the coherent absorption can also be achieved in terahertz band.The characteristics of transmission,reflection and absorption of the structure are studied in the case of single-beam incident electromagnetic wave,and in the case of two-beam incident electromagnetic wave,at the fixed frequency of 0.915 THz,the output electromagnetic wave intensity can be dynamically controlled from 0 to 90%,and the coherent control effect can be achieved.Finally,the circular dichroism of the structure in terahertz frequency band is studied.At 0.92 THz,the difference of the absorption efficiency of the structure is 0.18 for left circular polarized light and right circular polarized light.