The Research Of Terahertz Fingerprint Detection With Waveguide

Terahertz wave(THz)technology has been widely used in lots of fields because of its low photon energy and it is transparent to most of non-polar materials.It is a key direction in terahertz waveguide sensing to quantitative analysis samples.We come up with a way for designing terahertz waveguide sensors to realize the detection of samples with low quantity or concentration.The main work of this paper is described as follows:(1)We theoretically design a one-dimensional photonic crystal waveguide structure.Adjusting the size of structure to move the resonant frequency to match the eigen frequency of target sample to achieve the purpose of specific identification.Taking lactose as an example,a detection range of sample’s thickness from 1 μm to15 μm is achieved and outperforms the previous reported tens of microns.(2)We propose and design a hollow waveguide with the material of TOPASE.Taking the poisonous gas hydrogen cyanide(HCN)as an example for testing,the lowest detection limit for this photonic crystal fiber is 2 ppm.At the same time,the length of this fiber is 0.1 m which is suitable for real time poisonous gas detection and easy for integrating.(3)We propose and design a hollow waveguide with the material of polytetrafluoroethylene(PTFE).By taking the poisonous gas hydrogen cyanide(HCN)as an example,this waveguide achieves the purpose of low concentration gas detection of HCN.Under the standard atmospheric pressure,when the volume of HCN is 2 cubic centimeters per cubic meter of atmosphere(the concentration of HCN is 2 ppm),the transmittance can attenuate from 100% to 25% through waveguide of 1.28 m long.