Research On Tunable Terahertz Filters Based On Metamaterials

Terahertz band has developed rapidly in the sixth generation mobile communication,biological detection,medical imaging and other related fields because of its unique properties.As an ideal new type of artificial composite material that can manipulate electromagnetic waves at will,metamaterials are of great significance to the design and development of terahertz functional devices.Based on metamaterials,terahertz time-domain spectroscopy system and CST Studio Suite simulation software,the terahertz filter based on metal strip structure and diamond structure is studied in this paper.A terahertz filter based on metal strip structure is studied.By adjusting the structure parameters,the filter has the functions of narrowband filtering,dual frequency filtering for specific frequencies,and optical switching.The proposed device consists of a surface metal strip structure and a quartz substrate.By adjusting the structural parameters,the filter has the functions of narrowband filtering,dual frequency filtering for specific frequencies,and optical switching.The resonance intensity of the two resonance points can be comprehensively adjusted by changing the angle between the metal bar and the THz polarization.As the angle increases from 0 to 90 degrees,the transmissivity of 0.81 THz increases from-8.24 d B to-1.44 d B,and that of 1.37 THz increases from-9.61 d B to-2.11 d B.In addition,by changing the rotation angle between the metal strips in the cell,the resonance intensity at the corresponding frequency can be adjusted to make the filtering mode transition from the single resonance state to the double resonance state.The designed filter not only has the unique terahertz polarization direction detection function,but also has the advantages of large tunable range,double resonance,etc.A terahertz filter based on diamond structure is proposed and experimentally verified.The proposed metamaterial device consists of a surface diamond structure and a quartz substrate.The resonance characteristics of diamond with different widths and different rotation angles and the potential application of the device as a sensor are studied.By adjusting the structure width c of the diamond,the resonant peak frequency in the transmission spectrum can be adjusted independently.With the structure width c changing from 4μm increased to 12μm.The resonance point also moved from 2.12 THz to 2.46 THz,and the resonance intensity did not change significantly;The resonance intensity and frequency can be adjusted simultaneously by rotating the diamond shaped metamaterial structure.In addition,based on the excellent resonance strength of the structure,THz spectral characteristics of the structure in different refractive index liquids are simulated,and the sensing performance of the diamond structure metamaterial sensor is calculated quantitatively.The quality factor FOM reaches 9.It shows that the structure has good sensing properties and has broad application prospects in the super material terahertz biosensor.