Research On Terahertz Devices Based On Metasurfaces

Electromagnetic waves in the terahertz band has a good fingerprint spectrum discrimination ability and far less than the energy of X-rays.Therefore,the resonance characteristic spectral lines of matter can be obtained through terahertz waves to establish a database for future data collection and material identification.In addition,electromagnetic waves in the terahertz band have broadband characteristics,which also have potential in information transmission,absorbers,and other aspects.As a new type of artificially designed material,metasurface structures can be designed according to requirements to obtain some of the desired characteristics.In addition to locally enhancing the electromagnetic field,metasurface structures can also detect a small amount of samples and regulate the resonant frequency by adjusting structural parameters.In addition to locally enhancing the electromagnetic field,metasurface structures can also detect a small number of samples and regulate the resonant frequency by adjusting structural parameters.Therefore,combining electromagnetic waves in the terahertz band with metasurfaces can effectively improve the relevant performance of terahertz functional devices.The main content of this paper was the design of the structure and the improvement of performance.Three types of terahertz functional devices were proposed,including high Q-factor sensors,multi band sensors,and large bandwidth absorbers.Subsequently,simulation calculations were conducted using the simulation software CST Microwave Studio and detailed analysis was conducted on the structure design,simulation results,structural parameters,and sensing characteristics.The main contents are as follows:1.A unique E-shaped structure has been proposed,which can reduce radiation loss by adjusting the position of the grating arm to produce asymmetric and destructive suppression of dipole radiation.Meanwhile,the periodic arrangement of E-type terahertz metasurface structures can generate high Q-factor resonances.The sensing characteristics of this refractive index sensor based on metasurface structure were studied and its high sensitivity advantage was demonstrated.2.A new design of a multi band terahertz metasurface biosensor for early cancer detection has been proposed.The absorption spectra and polarization independence were analyzed under different design parameters,which improved the performance of the sensor by adjusting its absorption characteristics and provided calculation results.We studied the effects of refractive index and thickness of different samples on the sensor,and theoretically calculated the sensitivity of the sensor to basal cells,breast cells,cervical cells,and their corresponding cancer cells.3.A graphene terahertz metasurface absorber has been proposed.Firstly,through the analysis of resonance characteristics,it was found that the resonance of the sensor can be divided into localized surface plasmon resonance(LSPR)and propagating surface plasmon resonance(PSPR).Secondly,the highest absorption spectral line was obtained by optimizing the dielectric layer.At the same time,we also made adjustments to the structural parameters of the graphene layer.By adjusting the size structure,we determined the optimal set of parameters while maintaining the highest absorption peaks of LSPR and PSPR.Finally,the insensitivity and tunability of the structure were also studied.