Research On Tunable Metamaterial Devices Based On Phase Change Materials

Metamaterials are subwavelength structures that composed of periodically arranged meta-atoms which can be arbitrarily designed by people,it doesn’t exist in nature world.People can achieve unique electromagnetic properties beyond the limits of natural materials by carefully design its periodic meta-atoms,such as negative refractive index,super lens,invisible cloak,perfect absorber,and antenna performance enhancement,etc.The development of metamaterials has greatly improved people’s ability to manipulate electromagnetic waves,but with the rapid development of metamaterials people have gradually realized the inconvenience of untunable metamaterials,the design of dynamically tunable metamaterials has gradually attracted more and more attention.In this article,we integrated the phase-change material of vanadium dioxide and GST into the meta-atoms design and studied a variety of tunable and controllable metamaterials,and mainly designed the following metamaterial devices:First,we combined the phase-change material vanadium dioxide to realize the excitation of the dynamic toroidal dipole in the metamaterial.We designed one singlegap split ring toroidal dipole resonator and another double-gap split ring toroidal dipole resonator,their working frequencies are 0.46THz and 0.288THz respectively.In terms of absorption of electromagnetic wave,we designed a mid-infrared narrowband absorber based on the phase-change material GST,it has one 100%perfect absorptance peak at 89THz.By stimulating GST from crystalline state to amorphous state,its absorptance drops to 6%,the device shows a good switching effect.Finally,by using the phase transition of VO2 from insulator state to metal state we designed a multi-layer bifunctional metamaterial device,it can switch to different state between the electromagnetically induced transparency(EIT)phenomenon and linear polarization conversion,but the physical shape of the device will not change in any way.For electromagnetically induced transparency,it has a transmission window of 88.2%at 0.207THz because of the destructive interference between "bright mode" and "dark mode".When the device is working in linear polarization conversion state,the incident wave can be transformed to a cross-polarized wave.All the metamaterial devices we designed have dynamic control capabilities,and they are insensitive to polarization angle and incident angle.Therefore,the devices we designed have great potential in the actual manufacturing and application.