Research On Analogue Electromagnetically Induced Transparency And Sensing Based On Metamaterials

Metamaterial is a class of artificial composite materials which has sub-wavelength periodic structures.Because they exhibit many unique properties that natural materials do not have,they are of great research value and have attracted extensive research interests of many researchers.This article focuses on metamaterial sensors and electromagnetic-induced transparency effects(EIT)based on metamaterials.(1)A novel kind of sensors for simultaneous measurement of refractive index and temperature based on all-dielectric metasurfaces is firstly proposed.The metasurfaces are constructed by an array of silicon nanoblocks on top of the bulk fused silica substrate.We used three-dimensional full wave electromagnetic field simulation by finite integral method to accurately calculate the transmission spectrum of the metasurfaces.Two transmission dips corresponding to the electric and magnetic resonances are observed.Both dips shift as the ambient refractive index or the temperature changes.Simulation results show that the sensing sensitivities of two dips to the refractive index are 243.44 nm/RIU and 159.43nm/RIU,respectively,while the sensitivities to the temperature are 50.47 pm/°C and75.20 pm/°C,respectively.After introducing four holes into each silicon nanoblock,the sensitivities to the refractive index increase to 306.71 nm/RIU and 204.27nm/RIU,respectively.Our proposed sensors have advantages of polarization insensitive,small size,and low loss,which offer them high potential applications in physical,biological and chemical sensing fields.(2)We have designed aluminum-based metamaterials and silicon-based metamaterials with the same "glasses" shape to achieve EIT.We analyzed and compared the EIT performance in the near infrared waveband of these two metamaterials.The metallic EIT metamaterials with large radiation loss and ohmic heat loss have a smaller Q-factor than the dielectric counterpart with less energy loss,while having a higher sensitivity toward the ambient refractive index.The Q-factor of our designed aluminum metamaterial and silicon metamaterial are 10.06 and 412.6,respectively.Due to the optimization of the structure when designing,their sensitivities are 1642.97 nm/RIU and 433.05 nm/RIU,respectively,which are higher than most of their counterparts in the same waveband in the other literature,and they also has a good slow light effect.The EIT metamaterials that we designed have excellent performance,and to the best of our knowledge,we presents the first detailed comparison of EIT metamaterials made of dielectric and metal with similar structure;this paper may have certain instructive meaning for further research on metamaterial analogues of EIT in the future.(3)The bright mode and the dark mode in traditional EIT metallic metamaterials are connected by the near-field coupling.Here,we takes a different approach.Metal can be regarded as a perfect electrical conductor in the terahertz band,thus we combined the bright mode and the dark mode as a whole,and the bright mode excites the dark mode through the surface conductive current,and then the EIT is induced.We not only carried out simulation analysis,but also fabricated the metamaterials by lithography technique and wet etching process,and tested it with terahertz time domain spectroscopy system.It was found that the experimental results are in good agreement with the simulation.