Electromagnetically Induced Transparency-like Effect And Asymmetric Transmission Based On Chiral Metamaterials

Metamaterials are artificial materials with special properties,which usually have extraordinary physical properties or better working performance than natural materials.The shape and size of artificial structural units of electromagnetic metamaterials will affect their electromagnetic properties.Moreover,chiral metamaterials can achieve special functions by virtue of the particularity of chiral structure,and they usually control the circularly polarized component of electromagnetic wave.This thesis focuses on the research of chiral metamaterials,including two aspects:the first is optical rotation effect and electromagnetically induced transparency in chiral metamaterials;the second is asymmetric transmission device based on chiral metamaterials.In the study of optical rotation effect and electromagnetically induced transparency,a C₄ symmetric chiral metamaterial at about 13.4 GHz is designed and fabricated,which not only has optical rotation,but also can produce electromagnetically induced transparency.The transmission peak is located at 13.4 GHz,with a transmittance of 79.2%,and a rotation angle of 33°.In addition,the electrical and magnetic response characteristics of the chiral metamaterial are analyzed,and the relationship between optical rotation and electromagnetically induced transparency in the chiral metamaterial is revealed from a novel perspective.Based on this,the corresponding transmittance equation is established,and the transmission spectrum obtained by numerical fitting is basically consistent with the simulation results.This device has both electromagnetically induced transparency-like effect and optical rotation effect,so it has high transmittance at the optical rotation wavelength.In the aspect of asymmetric transmission with chiral metamaterials,an asymmetric transmission device based on Z-shaped chiral metamaterial is studied.The optical rotation characteristics and the transfer matrix of anisotropic optical elements are analyzed,and the asymmetric transmission device in microwave band is designed and fabricated.The experimental results show that the transmittance is 31.8%and the corresponding transmittance for the opposite propagating wave is 10.9%at 4.25 GHz.In addition,a multilayer asymmetric transmission device is designed,and the simulation results show that it can realize the asymmetric transmission of left-handed circularly polarized light in 1550 nm optical communication band.