Study On Polarization Device Applied In Mixed Oil Detection For Terahertz Frequency Region

In recent years,with the rapid development of methods to generate and detect terahertz radiation,THz has received great attention in the fields of wireless communication,radar imaging,biomedicine research,nondestructive testing and so on.And this is also because its low energy,strong penetrability through the non-polar material and having fingerprint absorption spectrum of many kinds of organic molecules.However,at present the application of terahertz mostly limited to direct using of terahertz,there is a lack of research on the polarization modulation of terahertz wave,and there are few kinds of polarization devices applied to THz wave band.So it has important practical value to study the polarization devices used in terahertz frequency region.We present a new terahertz polarization device by means of Brewster effect of a stack of silicon wafers,to overcome the shortcomings of polarization devices currently used in terahertz frequency region,which are expensive to produce,difficult to be process,and easy to generate Fabry-Perot echo effect et al..This paper introduces the designing theory in detail and discusses the type of the material used,the number of the wafers,and the geometric structure of the polarization device,based on the performance index of the polarizer.Furthermore,we also designed the bracket to use the polarizer more conveniently.Then according to the design,we manufactured the silicon group polarizer,established the experimental scheme and tested its performance.In order to facilitate processing the data,this paper also gives a brief introduction to the program and optimization of the data processing.The test results show that the polarizer designed in this paper meet the needs of polarization in terahertz wave band.The extinction ratio of the polarizer is higher than 1059,the maximum transmittance is higher than 99% and the polarizer can be used in 0 ~ 3THz frequency region.For different kinds of oil with different concentrations of chiral compounds,the opticity in terahertz frequency region is different.We used the silicon wafer polarizer to measure 97# gasoline,0# diesel and their mixture,and realized detection of mixed oil.