| The high bandwidth and data rate demands of future wireless communications,cannot be met by existing technologies for naturally occurring 3D materials.The terahertz(THz)band refers to the electromagnetic frequency range between the millimeter waveband and the infrared waveband,which has wide application potential in the field of high-speed wireless communication networks.Recently,two-dimensional materials(2D materials)such as graphene,Dirac semimetals,vanadium dioxide,and black phosphorus can effectively improve the performance of terahertz devices.Therefore,two-dimensional materials have become a research hotspot in recent years,and have potential applications in the fields of optical integrated circuits,optical communications and sensing.Plasmon-induced transparency(PIT)is an important phenomenon of two-dimensional materialsIn this background,the paper analyzes the basic principles of PIT,and studies the PIT effects and device design for different two-dimensional materials,which has potential value for the design and application of terahertz devices.The main research contents of this paper include the following four aspects:(1)A single-band PIT model based on silver nanodisk and nanorods with bright--dark mode coupling is designed.The bright--dark--dark mode coupling,dark--bright--dark--dark mode coupling and dark--dark--bright--dark--dark mode coupling is generated by increasing the number of silver nanorod resonators.The PIT effect with dual-band,triple-band and four-band is further achieved through the near-field coupling of nanodisk and rods and the mutual coupling of nanorods.Finally,based on the four-band PIT model,an ultrasensitive refractive index sensor is designed.Its maximum sensitivity reaches 326.2625(THz/ RIU),and the maximum figure of merit reaches 26.4(1/ RIU),exhibiting excellent sensing performance.(2)Using the coupling of black phosphorus parallel nanoribbons with different lengths and the coupling of black phosphorus nanorods having different lengths,based on the bright mode-bright mode coupling,single-band,dual-band and multi-band PIT effects are realized.Secondly,the PIT effect is theoretically explained by using the radiating two-oscillator model.At the same time,by changing the relaxation rate of black phosphorus,the tunability of the resonant frequencies and transmittance of the transparent peaks of each PIT model is realized.Finally,the sensing properties of the PIT model of black phosphorus nanorods with different lengths are investigated,and the sensitivity reaches 6.11(um/ RIU),showing good sensing performance.(3)A dual-tunable single-band,dual-band,triple-band and four-band absorbers based on Dirac semimetals and vanadium dioxide are designed.Firstly,the resonant frequencies and absorptivity of all absorbers can be dynamically adjusted by changing the Fermi energy of dirac semimetal and the conductivity of vanadium dioxide.Secondly,the single-band absorber is theoretically analyzed by the coupled mode theory,and the dual-band absorber is theoretically discussed by using the radiating two-oscillator model.The application potential of the dual-band absorber as a refractive index sensor is further analyzed.Its sensitivity reaches 15.74(um/ RIU)and the figure of merit reaches 6.54(1/ RIU),showing good sensing performance.(4)A PIT model based on a hybrid structure of silver rods,silver disk and graphene is proposed.Based on the weak hybridization of the two bright-mode units,single-band,dual-band and triple-band PIT effects are realized.The tunability of the resonance frequencies and transmittance at the transparent peaks of each PIT model is achieved by changing the chemical potential of graphene.The variation law of the single-band PIT effect with the background refractive index is analyzed,and the model has a sensitivity of 3.9(um/ RIU),having good sensing performance. |
