發(fā)布時(shí)間：2018-01-13 07:16

  本文關(guān)鍵詞：支持表面等離子激元回音壁模式的石墨烯納米腔的研究　出處：《華僑大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 回音壁模式 表面等離子激元 石墨烯 可調(diào)諧 耦合

【摘要】：表面等離子體激元(Surface Plasmon Polaritons,SPPs)的高局域性,與回音壁模式(Whispering Gallery Mode,WGM)諧振腔的共振模式特性相結(jié)合可以構(gòu)成具有高品質(zhì)因子(Quality Factor,Q值)、小模式體積(Mode Volume,V_m)的表面等離子體激元回音壁模式諧振腔,這種諧振腔由于克服了傳統(tǒng)介質(zhì)WGM微腔所受的衍射極限的限制,可以將尺寸縮小到納米量級(jí)。對(duì)于傳統(tǒng)的貴金屬材料來(lái)說(shuō),例如金和銀,一旦其結(jié)構(gòu)固定,SPPs的性質(zhì)便難以調(diào)節(jié),并且在傳統(tǒng)金屬界面上傳播的SPPs損耗較大,因此基于金屬的SPPs裝置的優(yōu)良特性受到了限制。石墨烯作為單碳原子層的二維(2 dimension,2-D)材料,當(dāng)電導(dǎo)率虛部為正值時(shí),石墨烯能夠支持橫磁(Transverse Magnetic,TM)模式的SPPs。并且石墨烯的高限制性、低損耗、易于調(diào)節(jié)等特性已經(jīng)在理論上和實(shí)驗(yàn)上得到了證實(shí)。通過(guò)改變化學(xué)摻雜或者改變施加于石墨烯上的靜電場(chǎng)可以改變石墨烯化學(xué)勢(shì),進(jìn)而改變石墨烯電導(dǎo)率,從而調(diào)制其支持的SPPs的性質(zhì)。本論文利用了石墨烯的局域可調(diào)諧性,在一片石墨烯上構(gòu)造等離子體激元回音壁模式諧振腔,模擬計(jì)算其模式特性隨腔體的幾何參數(shù)和石墨烯的材料參數(shù)的變化,并分析探討其物理機(jī)制。本文利用有限元方法數(shù)值模擬計(jì)算了石墨烯等邊三角形納米腔,分析了納米腔的模式特性與腔尺寸R_1、頻率、石墨烯動(dòng)量豫馳時(shí)間t和石墨烯化學(xué)勢(shì)μ_c之間的關(guān)系。研究結(jié)果表明,在近紅外波段,當(dāng)其他參數(shù)保持不變時(shí),腔Q值隨R_1的變化不顯著,而頻率、τ以及μ_c的變化對(duì)腔Q值的影響較大。當(dāng)真空波長(zhǎng)大約在1.415μm時(shí),該腔可支持Q值約為147.93的一種高階回音壁模式,對(duì)應(yīng)的模式體積可達(dá)10~(-7)(λ_0/2n)~3量級(jí),purcell因子能達(dá)到108量級(jí)。其次對(duì)連接有頂級(jí)輸出波導(dǎo)的石墨烯等邊三角形納米腔進(jìn)行模擬數(shù)值計(jì)算,分析了該結(jié)構(gòu)的模式特性和輸出特性隨結(jié)構(gòu)的幾何尺寸以及石墨烯材料參數(shù)的變化。研究結(jié)果表明,當(dāng)μ_(c1)和μ_(c2)分別設(shè)定為0.9eV和0.59eV時(shí),R_1為30nm且輸出波導(dǎo)寬度為5nm的該種集成等離子體器件中purcell因子可達(dá)107量級(jí),輸出系數(shù)達(dá)到20.2%。在本文中除了探討石墨烯等邊三角形納米腔以外,我們利用同樣的方法對(duì)石墨烯納米盤的耦合進(jìn)行數(shù)值分析,對(duì)于基于石墨烯納米盤的雙原子等離子體分子,主要分析其兩盤間距g以及兩盤大小差異對(duì)模式耦合的影響。研究結(jié)果表明,隨著g的減小該結(jié)構(gòu)中存在簡(jiǎn)并模式分裂的現(xiàn)象,并且存在基模TM_(8,1)和高階模TM_(5,2)耦合的情況;兩盤大小差異的變化也對(duì)該等離子體分子的模式耦合產(chǎn)生影響。對(duì)于基于石墨烯納米盤的三原子等離子體分子,主要研究對(duì)稱性退化(由等邊三角形結(jié)構(gòu)逐漸變化成為線性鏈結(jié)構(gòu))對(duì)于模式耦合特性的影響。研究結(jié)果表明,隨著結(jié)構(gòu)的變化,模式電場(chǎng)E_z的分布,及其對(duì)應(yīng)的頻率與Q值也逐漸發(fā)生相應(yīng)的變化,當(dāng)a=135時(shí)其中一種耦合模式的Q值可達(dá)105量級(jí)。
[Abstract]:Surface Plasmon Polaritons (SPPs). And the echo wall pattern is the whispering Gallery Mode. The combination of the resonance mode characteristics of the WGM resonator can form a high quality factor (Q value) and a small mode volume mode (Volume). The surface plasmon resonator echo mode resonator cavity, which overcomes the diffraction limit of the traditional dielectric WGM microcavity. For traditional precious metal materials such as gold and silver it is difficult to adjust the properties of SPPs once their structure is fixed. And the SPPs loss propagating on the traditional metal interface is larger. Therefore, the excellent properties of metal-based SPPs devices are limited. Graphene, as a two-dimensional dimentision2-D) material of mono-carbon atomic layer, has a positive conductivity when the imaginary part of conductivity is positive. Graphene can support the SPPsof Transverse Magneticum (TM) mode, and the graphene has high limit and low loss. The easy-to-adjust properties have been proved theoretically and experimentally. By changing the chemical doping or changing the electrostatic field applied to graphene, the chemical potential of graphene can be changed and the conductivity of graphene can be changed. Therefore, the properties of the supported SPPs are modulated. In this paper, the plasmon echo wall mode resonator is constructed on a graphene piece by using the local tunability of graphene. The variation of the mode characteristics with the geometric parameters of the cavity and the material parameters of graphene is simulated, and its physical mechanism is analyzed and discussed. In this paper, the equilateral triangular nano-cavities of graphene are numerically simulated by the finite element method. The relationship between the mode characteristics of the nanocavity and the cavity size, frequency, graphene momentum relaxation time t and graphene chemical potential 渭 c was analyzed. When the other parameters remain unchanged, the Q value of the cavity does not change significantly with the R _ S _ 1, while the changes of the frequency, 蟿 and 渭 _ C have a great effect on the Q value of the cavity, when the vacuum wavelength is about 1.415 渭 m. The cavity can support a high-order echo wall model with Q value of 147.93, and the corresponding volume of the model can reach 10 ~ 10 ~ 7 ~ (-1) (位 _ 0 / 2 ~ (2) n ~ (-1)). The purcell factor can reach the order of 10 8. Secondly, the graphene equilateral triangular nanocavity with top output waveguide is simulated. The mode and output characteristics of the structure are analyzed with the geometric size of the structure and the parameters of graphene materials. When 渭 s / c _ (1) and 渭 _ s _ s _ 2) were set to 0.9eV and 0.59eV, respectively. The purcell factor of the integrated plasma device with 30 nm R1 and 5 nm output waveguide can reach 107 orders of magnitude. The output coefficient is 20.20.In this paper, we use the same method to analyze the coupling of graphene nanodisk in addition to the discussion of graphene equilateral triangular nano-cavity. For diatomic plasma molecules based on graphene nanodisk, the effects of the distance between two disks g and the size difference of the two disks on the mode coupling are analyzed. With the decrease of g, there is a degenerate mode splitting in the structure, and there is a coupling of the base mode TMSP 8 / 1) and the higher order mode TMSP 5 / 2). The variation of the size of the two disks also affects the mode coupling of the plasma molecule, for the triatomic plasma molecule based on the graphene nanodisk. The effect of symmetry degradation (from equilateral triangular structure to linear chain structure) on the mode coupling properties is studied. The results show that the distribution of mode electric field E _ z varies with the structure. The corresponding frequency and Q value change gradually, when a = 135, the Q value of one of the coupling modes can reach 105 orders of magnitude.
【學(xué)位授予單位】：華僑大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O539;O613.71
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本文編號(hào)：1417978