Design And Characteristic Of All-Dielectric Metamaterial Terahertz Functional Device

Terahertz wave is usually defined as the electromagnetic radiation with special electromagnetic characteristic,which frequency between 100 GHz-10 THz.Terahertz technology is a very important cross-cutting frontier field,which is widely used in imaging systems,security inspection and radar fields.Terahertz technology provides an effective means for biological information detection,due to the vibration and rotation frequencies of biological macromolecules in nature are in terahertz range.The terahertz metamaterial absorber can effectively improve the detection effect,so the metamaterial absorber has great potential in the preparation of high-sensitivity biochemical sensors.Among them,the all-dielectric metamaterial absorber has attracted widespread attention due to the low loss,easy processing,and more stable performance.Two absorbers based on all-dielectric materials are investigated in this paper.They can achieve single-band or multi-band absorption with high quality factor Q in the terahertz range,respectively.The single-band absorber consists of silicon cylinder and polyimide substrate.The results show that the metamaterial absorber can achieve high absorption of 99.75%at 0.57 THz.The absorber is insensitive to polarization,and the peak absorbance remained higher absorption over a wide range of incident angles.Due to the light modulation characteristics of silicon material,this absorber could achieve photo-excitation.In addition,the absorber is sensitive to the refractive index of the analyte on the absorber's top,the absorber has potential applications in the fields of THz sensing.The multi-band absorber is composed of one-dimensional silicon grating,which can achieve multi-band absorber in the working frequency range of 0.2-2.5 THz,and the absorption rate is greater than 91%,with a higher quality factor Q.The experimental results are in good agreement with the simulation results.Similar to the single-band absorber the multi-band absorber can also achieve photo-excitation,while also having the sensing characteristics.In order to explore the sensing performance of the absorber,different concentrations of pesticide solution were dropped on the surface of the metamaterial.We testing the reflection spectrum of the absorber.The experimental results show that the absorption amplitude at the resonant peak has a good linear relationship with the concentration of pesticide solution.The multi-band absorber has a great potential in pesticide detection.