Research Of Circular Dichroism EIT Effect Based On Metastructures

In this dissertation,the tunable EIT effect with circular dichroism is realized in the bilayered metastructure based on fabrication difficulties of their 3D counterparts.The excellent agreement between experimental data and simulation data confirms that the phenomenon is existent.Furthermore,theoretically studied and optimized the circular polarization dichroism devices.At last,in view of the unique phase transition properties of vanadium dioxide and little research in the microwave range,EIT-like active control can be achieved by using vanadium dioxide under microwave frequency bands,which paves the way for their applications in programmable material,slow light,microwave photonics and superconducting quantum circuit regions.?1?A bilayered metastructure of triple-arc resonator?TAR?was designed,which is composed of a single-arc resonator?SAR?and a double-arc resonator?DAR?.The calculation results show that circular polarization selectivity is achieved in the metastructure.Under the right-handed light incident,the ETT-like effect is generated due to the coupling of chiral and non-chiral modes,and the incident Gaussian pulse produces a group velocity delay of 1.77ns.More importantly,the proposed metastructure also has good circular dichroism tunability which can be obtained by adjusting the SAR rotation angle.The experimental samples were fabricated by Printed Circuit Board processing technology,and the simulation data was verified by the microwave network analyzer,which proved the existence of ETT-like.?2?we theoretically study and optimize the design of a two-dimensional metastructure circular polarization dichroism device based on the circular dichroism tunable phenomenon that has been discovered.The simulation data shows that the circular polarization dichroism of the metastructure is up to 68%at 15.6 GHz.The circular dichroism effects of the transmission and reflection conversion modes generated by different circularly polarized light incident on the metastructure are studied by simulation.Furthermore,the mechanism of the circular dichroism phenomenon based on electromagnetic induction transparency are studied.the RCP mode coupling of SAR and DAR leads to the conventional transparent window locating inside two reflecting mode of SAR and DAR.For LCP,the EIT-like phenomenon is a result of transmitting mode of DAR coupled with a reflecting mode of SAR.?3?Based on the above design,the modulation of transmission is mainly tuned by changing the geometry.Combined with the vanadium dioxide material with semiconductor-to-metal phase transition,the active tuning of EIT-like can be realized.By replacing the material of top intermediate layer with VO₂,the dynamical modulation of transmission can be modulated from about 0.2%to 58%.The experimental samples were fabricated,and the simulation data was verified by the microwave network analyzer,which proved the active control of electromagnetically induced transparency.