發(fā)布時(shí)間：2019-01-24 21:57

【摘要】：太赫茲波具有穿透、低能量、寬帶及光譜分辨等獨(dú)有的特性,賦予了其廣泛的應(yīng)用前景,并將給成像技術(shù)、光譜技術(shù)、通信技術(shù)及安全檢測方面帶來深遠(yuǎn)的影響。納米材料的出現(xiàn),給太赫茲技術(shù)的發(fā)展帶來了新的契機(jī)。碳納米管有著極具吸引力的固有屬性,并得到了人們廣泛的關(guān)注。碳納米管的應(yīng)用也從直流一直擴(kuò)展到紅外區(qū)域。但是,相比于微波及紅外區(qū)域,碳納米管在太赫茲區(qū)域的基礎(chǔ)研究相對較少。本文對碳納米管在太赫茲波的電磁傳播特性進(jìn)行了研究。基于等效介質(zhì)的Maxwell-Garnett模型及Drude-Lorentz模型對單壁碳納米管(single-walled carbon nanotubes,SWNTs)、雙壁碳納米管(double-walled carbon nanotubes,DWNTs)、氫雜化碳納米管(H-deped CNTs)的電學(xué)屬性進(jìn)行建模及數(shù)值擬合。給出了碳納米管的介電系數(shù)、介質(zhì)損耗角正切及實(shí)電導(dǎo)率隨頻率變化的曲線。隨后基于輔助差分方程的時(shí)域有限差分(ADE-FDTD)方法推導(dǎo)出碳納米管的場及電流方程,并驗(yàn)證了方法的有效性。對不同厚度的碳納米管的屏蔽效能進(jìn)行了比較,結(jié)果表明碳納米管在電磁屏蔽方面有潛在的應(yīng)用。針對可應(yīng)用于太赫茲器件的Si基片上的碳納米管分層介質(zhì)在太赫茲頻段的傳播進(jìn)行了討論,結(jié)果表明多反射及傳輸現(xiàn)象存在其中。碳納米管的手性矢量決定了其結(jié)構(gòu),同時(shí)也決定了其很多的物理性質(zhì)。本文通過對手性材料的分析,在Lorentz-Condon模型的基礎(chǔ)上結(jié)合Drude-Lorentz模型,給出了用于FDTD計(jì)算的手性碳納米管模型。用ADE-FDTD方法推導(dǎo)出手性碳納米管的場方程迭代公式,驗(yàn)證了方法及計(jì)算結(jié)果的正確性,并對太赫茲波下手性碳納米管的反射系數(shù)及傳輸系數(shù)進(jìn)行了計(jì)算。通過對手性碳納米管的分析,結(jié)果表明手性碳納米管中存在旋光性及圓二色性,這將對以后的應(yīng)用有一定的參考作用。最后本文用等效電路方法對手性介質(zhì)進(jìn)行了研究,給出了等效電路每單元部分的相位偏移和特征阻抗,并用ADS進(jìn)行了驗(yàn)證。
[Abstract]:Terahertz wave has unique characteristics such as penetration, low energy, wide band and spectral resolution, which will have a great impact on imaging technology, spectral technology, communication technology and security detection. The appearance of nanomaterials brings new opportunities to the development of terahertz technology. Carbon nanotubes (CNTs) have attracted much attention because of their attractive properties. The application of carbon nanotubes also extends from DC to infrared region. However, compared with microwave and infrared regions, the basic research of carbon nanotubes in terahertz region is relatively small. The electromagnetic propagation characteristics of carbon nanotubes in terahertz wave are studied in this paper. On the basis of Maxwell-Garnett model and Drude-Lorentz model of equivalent medium, single-walled carbon nanotubes (single-walled carbon nanotubes,SWNTs), double-walled carbon nanotubes (double-walled carbon nanotubes,DWNTs), double walled carbon nanotubes (double-walled carbon nanotubes,DWNTs), The electrical properties of hydrogen hybrid carbon nanotubes (H-deped CNTs) were modeled and numerically fitted. The curves of dielectric coefficient, dielectric loss angle tangent and real conductivity with frequency are given. Then the field and current equations of carbon nanotubes are derived by the finite difference time domain (ADE-FDTD) method based on the auxiliary difference equation, and the validity of the method is verified. The shielding efficiency of carbon nanotubes with different thickness is compared. The results show that carbon nanotubes have potential applications in electromagnetic shielding. The propagation of layered carbon nanotubes (CNTs) on Si substrates which can be used in terahertz devices at terahertz band is discussed. The results show that the phenomenon of multi-reflection and transmission exists. The chiral vector of carbon nanotubes determines its structure and many physical properties. Based on the Lorentz-Condon model and Drude-Lorentz model, a chiral carbon nanotube (CNT) model for FDTD calculation is presented by the analysis of chiral materials. The iterative formula of field equation for chiral carbon nanotubes is derived by ADE-FDTD method, which verifies the correctness of the method and the calculation results. The reflection coefficient and transmission coefficient of terahertz wave chiral carbon nanotubes are calculated. Through the analysis of chiral carbon nanotubes, the results show that there are optical and circular dichroism in chiral carbon nanotubes, which will be useful for future applications. Finally, the chiral dielectric is studied by using the equivalent circuit method. The phase offset and characteristic impedance of each unit of the equivalent circuit are given and verified by ADS.
【學(xué)位授予單位】：電子科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：O441.6;TB383.1
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本文編號：2414899