Research On Metasurface-based Terahertz Functional Devices

While metasurface,as a kind of artificial two-dimensional periodic structure,can realize such functions and properties that natural material can not realize.Recently,there are increasing development of terahertz science and technology.However,compared with it,the research on related devices is still a bit lagging behind which greatly limiting the continuous improvement of terahertz science and technology.Therefore,it is extremely important to find a fabrication scheme for terahertz devices that is compacted,low cost,fast fabrication and easy to control.metasurface-based devices have many merits such as little thickness,compact structure,easy-to-control and other properties,In this paper,study on metasurface-based terahertz devices are explored.The main works of this article are following.(1)The polarization of reflective metasurface-based terahertz wave plate is explored.In simulation,by changing the interleaved distance,the anomalous refraction for different kinds of wave plate arrays are calculated.As for experiment,such metasurface-based samples are fabricated employing photolithography and electron beam evaporation technique.Optical system is also built for measurement and the simulation results are verified.The results show that such metasurface-based wave plate is viable for terahertz application.(2)The spiral phase plate(SPP)for terahertz vortices is designed and fabricated utilizing metasurface-based antennas.Firstly,FDTD Soultion software is used to simulate and verify the anomalous refraction phenomenon of metasurface-based antennas which is in perfect agreement with the generalized Snell’s law.According simulation results,SPPs with different topological charges are designed.Then,such metasurface-based samples are fabricated employing photolithography and electron beam evaporation technique.Finally,optical system is also built for measurement and the simulation results are verified.(3)Metasurface-based terahertz lens with focused effect is designed.The optical characteristics,such as numerical aperture and so forth,in terahertz band is simulated employing FDTD Solution software.And analysis and explanation are also provided for simulation results with different conditions.In terahertz band,such metasurface-based focused lens works well at the wavelength from 2.7 mm to 3 mm which also verifies the broadband property of metasurface-based structure.In general,terahertz devices fabrication using metasurface technique such as wave plate,the spiral phase plate and focused lens,provides an alternative idea and method for continuous improvement for terahertz science.