【摘要】：石墨烯作為一種二維材料,已經(jīng)被廣泛應用于光電器件的制作。復折射率和電導率是反映其電學特性和光學特性的兩個重要參數(shù)。傳統(tǒng)測量復折射率的方法如橢偏法具有測量儀器昂貴復雜和光學建模難度大的缺點,同時測量過程中沒有引入光波導,測量結果對石墨烯光電器件的設計參考價值不大。傳統(tǒng)測量石墨烯電導率的方法需要在其表面蒸鍍金屬電極,工藝難度大,且引入了接觸電阻。因此,設計一種石墨烯混合光波導結構的測量石墨烯復折射率和電導率對于石墨烯光電器件的研究具有重要的意義。本論文基于上述研究背景,提出了一種石墨烯-長周期光纖光柵混合波導的結構用于測量石墨烯復折射率和電導率,重點研究了這一混合波導的測量理論和制備實驗,主要完成以下工作:首先,本文對石墨烯基本光電特性和長周期光纖光柵的理論進行了闡述。針對石墨烯復折射率電導率的關系進行了探討,分析了其可調控性。根據(jù)耦合模理論分析了長周期光纖光柵的透射率,且對其透射譜進行仿真,為后文石墨烯-長周期光纖光柵混合波導的建模奠定了理論基礎。其次,本文根據(jù)兩種方法建立了混合波導模型的包層模本征方程。對于第一種石墨烯復折射率包層模型,本文通過求解其本征方程,分析了石墨烯折射率實部和虛部對求解結果的影響,研究了石墨烯折射率實部和虛部對長周期光纖光柵諧振波長的影響。對于第二種表面電流模型,從電場的矢量模型出發(fā),推導了其包層模本征方程,利用圖解法研究了其求解結果。然后,本文對長周期光纖光柵的制作和石墨烯的制備進行了研究,利用拉曼光譜對石墨烯進行了表征,完成了石墨烯到長周期光纖光柵的轉移實驗,為后續(xù)測量混合波導傳輸特性的實驗研究奠定了基礎。最后,對石墨烯-長周期光纖光柵混合波導的透射譜展開實驗測量,對比之前的理論模型,計算了石墨烯的復折射率和電導率,分析了測量誤差。這一復合波導的結構增強了長周期光纖光柵對外界環(huán)境變化的靈敏度。因此,這一結構也可以實現(xiàn)對外界環(huán)境,如液體折射率等的高靈敏傳感。
[Abstract]:As a two-dimensional material, graphene has been widely used in the fabrication of optoelectronic devices. The complex refractive index and conductivity are two important parameters reflecting their electrical and optical properties. The traditional methods of measuring complex refractive index, such as ellipsometry, have the disadvantages of expensive and complicated measuring instruments and difficult optical modeling. At the same time, optical waveguides are not introduced in the measurement process, so the results are of little reference value to the design of graphene optoelectronic devices. The traditional method of measuring the conductivity of graphene requires evaporation of metal electrode on its surface, which is very difficult, and the contact resistance is introduced. Therefore, the design of a graphene mixed optical waveguide structure to measure the graphene complex refractive index and conductivity is of great significance for the study of graphene optoelectronic devices. Based on the above research background, a structure of graphene / long period fiber grating hybrid waveguide is proposed to measure the complex refractive index and conductivity of graphene. The main work is as follows: firstly, the basic photoelectric properties of graphene and the theory of long period fiber grating are described. The relationship of complex refractive index conductivity of graphene was discussed and its controllability was analyzed. Based on the coupled mode theory, the transmittance of long-period fiber grating is analyzed, and its transmission spectrum is simulated, which lays a theoretical foundation for the modeling of graphene long-period fiber grating hybrid waveguide. Secondly, in this paper, the eigenequations of the cladding model of the mixed waveguide model are established according to two methods. For the first graphene complex refractive index cladding model, the effect of real and imaginary parts of graphene refractive index on the solution results is analyzed by solving its intrinsic equation. The effect of the real and imaginary parts of graphene refractive index on the resonant wavelength of long period fiber grating is studied. For the second surface current model, the eigenequation of the cladding model is derived from the vector model of the electric field, and the solution results are studied by using the graphical method. Then, the fabrication of long-period fiber gratings and the preparation of graphene were studied. The graphene was characterized by Raman spectroscopy, and the transfer experiment from graphene to long-period fiber grating was completed. It lays a foundation for the experimental study of the transmission characteristics of hybrid waveguides. Finally, the transmission spectrum of graphene / long-period fiber grating hybrid waveguide is measured experimentally. Compared with the previous theoretical model, the complex refractive index and conductivity of graphene are calculated, and the measurement errors are analyzed. The structure of the composite waveguide enhances the sensitivity of the long period fiber grating to the change of the external environment. Therefore, the structure can also achieve high sensitivity to the external environment, such as refractive index of liquid.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TN253

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本文編號：2218438