Practical Research Of Terahertz Surface Plasmon Polariton Filter And Sensor (1)

As terahertz measuring carriers, terahertz functional devices become the focus ofresearch in the practical process of terahertz technology. However, excellentfunctional materials is a necessary condition for the development of functionaldevices. In the terahertz practical process, tunability is a necessary condition of thefilter, and the sensor with high sensitivity is required to detect and distinguish variousindistinguishable substances. In order to promote the practical research of terahertztechnology, this dissertation has made a preliminary study on above issues. The maincontents are summarized as follows:1. Based on the theory of solid-state physics, Drude model is used to solve thedielectric function of the conductor in electromagnetic field and the expression ofBulk Surface Plasmon (Bulk SP). Then the classified Maxwell equations are derivedto find out the relationship between SPP and Bulk SP, and the properties of SPPdispersion are obtained. Finally, five methods for exciting SPP are introduced.2. In order to widen types of terahertz functional materials, the dielectricproperties of functional ceramics materials in the range of terahertz have been studied.First, we briefly introduced the characteristics, applications, preparation technologyand the light control characteristic of dielectric constant in the range of terahertz ofCCTO ceramic. Then the dielectric properties of BLT and BNT ceramic from KHz toTHz were detailed studied. The study shows that the dielectric constant of BLT andBNT ceramic keep steadier from KHz to THz, and can be controlled by temperaturefrom KHz to GHz. Due to the limited experiment system conditions, the temperaturecontrol characteristic of BLT and BNT ceramic haven’t been verified.3. We have made a preliminary study on the tunable THz-SPP filter. First, we gota controllable parameters substrate dielectric permittivity by combining the THz-SPPfilter theory and numerical simulation. Considering SPP resonance peak position, theQ value, processing factors, material and thickness, we listed four structural designannouncements. Meanwhile, we designed and analysed three structural schemes thecomposite structure of semiconductor-metal or superconductor-metal, the compositestructure of functional ceramic-metal and the nematic liquid crystal structure. Finally,the preparation process of the tunable THz-SPP filter was detailed described. 4. We have made a study on surface plasmon enhanced terahertz spectroscopicdistinguishing between isomers in powder form. First, the sensor which is afreestanding stainless steel sheet perforated with an array of subwavelength holes isused to study the effect of a lactose overlayer of different thicknesses on terahertztransmission. Then we get the final resonance frequency ωfwhich can be consideredas a characteristic index to distinguish various dielectric substances in powder form.Based on the above studies, an experiment was carried out to distinguish betweenglutamic acid isomers, L-glutamic acid (Aladdin) and D-glutamic acid (Aladdin)which are classified as enantiomers. The experimental result shows a remarkabledistinction in the terahertz spectra reaching22GHz.