Reserach On Mode Control And Substance Detection In Hybrid Metamaterial System

Molecular vibrational spectroscopy plays an important role in chemical detection and biological sample identification.In recent years,people have studied more and more terahertz waves.Terahertz(THz,1THz=10THz)is between microwave and infrared.The area of electromagnetic radiation belongs to the far infrared area.Since the energy of the terahertz wave is very close to the energy of the interaction between the molecules,in the detection of the terahertz wave,the object to be detected is not damaged,and the nondestructive detection purpose is achieved.In this process,a terahertz time domain spectroscopy system is required.However,for the detection of trace film molecules,the terahertz time-domain spectroscopy system has been hindered from being applied in actual detection.Therefore,with the use of metamaterial structure devices,the method of using the near-field coupling of electromagnetic waves to improve the detection sensitivity of the system has also been favored by more and more scholars.This paper mainly proposes a kind of research based on mode regulation and substance detection in Hybrid metamaterial system.The main research contents include the following two parts:(1)At present,most of the research based on metamaterials for biomolecules,the general research direction is to improve the resonance of the electromagnetic metamaterial by increasing the Q value of the electromagnetic metamaterial and using the relative refractive index of the material to control the effective refractive index of the system.Location,the main physical mechanism of this traditional approach is the use of LC resonance or dipole resonance of metamaterial sensors.The evaluation criterion for this kind of sensor is to use the FOM(figure of merit)value to evaluate the performance of the sensor.In this paper,we mainly propose a high-extinction ratio electromagnetically induced transparent integrated chip sensor based on single-layer metamaterial,and carried out Experimental verification.The device structure involves four mirrorsymmetric coupled split-ring resonators(SRRs)that exhibit a bright-dark-dark-bright hybrid mode.The electromagnetically induced transparency effect is achieved by the coupling between the bright mode and the dark mode.Since the electric and magnetic dipoles of the two dark modes in the cell are opposite in direction,the radiation loss is suppressed and a high extinction ratio characteristic is obtained.The classical coupling model is used to analyze the transmission characteristics of the device,and the parameters of the device are demonstrated.And using the high Q value of this device for thin film molecular detection applications.The FOM obtained therein was 2.86.(2)Based on the absorption-induced transparency effect,the terahertz photon integrated biodetection chip is designed,which is mainly different from the first detection scheme,which can effectively and qualitatively detect trace thin film molecules.Under the premise of not changing the structure of the terahertz time domain spectrum system,the sensitivity to biomolecule detection is effectively improved.The experimental results show that the open resonant ring chip(SRR)is strongly coupled with L-tartaric acid molecules under low temperature conditions.The extinction ratio of the detection signal can be significantly increased from 1.75 dB to 4.5 dB,numerical calculations confirm and explain the experimental observations.By detuning the resonance of the metamaterial,the vibrational spectral signals of the coupled Hybrid system are tuned.When the SRR and the molecular vibration resonance frequency are closely aligned,a clear mode split is observed,resulting in a transparent vibration peak with an enhanced extinction ratio.The method detects the spectrum of trace film molecular vibration by absorption-induced transparent mechanism,showing great potential for application in thin film sensing.