本文關(guān)鍵詞：幾種周期性亞波長(zhǎng)結(jié)構(gòu)的光學(xué)特性及其器件設(shè)計(jì)　出處：《江蘇大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 亞波長(zhǎng)光柵 原子光學(xué)晶格 超寬帶反射鏡 反射聚焦

【摘要】：隨著激光加工技術(shù)的不斷進(jìn)步和成熟,人們對(duì)材料的加工技術(shù)已經(jīng)可以達(dá)到納米尺度的精度。這為亞波長(zhǎng)結(jié)構(gòu)光學(xué)性質(zhì)的研究提供了條件,而亞波長(zhǎng)結(jié)構(gòu)也因?yàn)槠洫?dú)特的光學(xué)特性正吸引了越來(lái)越多的關(guān)注。本文首先介紹了亞波長(zhǎng)金屬結(jié)構(gòu)及亞波長(zhǎng)介質(zhì)結(jié)構(gòu)的研究進(jìn)展,并討論了表面等離子激元的特性。接著,本文討論了二維周期性納米金屬圓柱結(jié)構(gòu)的近場(chǎng)光學(xué)特性,討論了結(jié)構(gòu)參數(shù)對(duì)其近場(chǎng)暗中空模式的影響,并結(jié)合范德瓦爾斯勢(shì)及自發(fā)輻射來(lái)討論原子囚禁的可能性。之后,本文提出了一種基于亞波長(zhǎng)梯形介質(zhì)光柵的高帶寬、超高反射率的反射鏡,并討論結(jié)構(gòu)參數(shù)對(duì)于反射帶寬的影響。最后,提出了一種利用亞波長(zhǎng)介質(zhì)光柵實(shí)現(xiàn)反射聚焦的方法,并討論了結(jié)構(gòu)參數(shù)對(duì)反射鏡相位的影響。在第二部分中,提出一種采用金屬圓柱陣列實(shí)現(xiàn)二維原子光學(xué)晶格的方案,利用有限元數(shù)值模擬方法研究了表面等離子激元特性,并考慮相鄰圓柱的近場(chǎng)耦合,得到了三維光強(qiáng)分布。分析了冷原子所受光學(xué)勢(shì)與范德瓦爾斯勢(shì)的作用,討論了總勢(shì)場(chǎng)分布及勢(shì)阱中心位置與結(jié)構(gòu)參數(shù)的依賴關(guān)系。研究發(fā)現(xiàn),金屬納米圓柱形成的光學(xué)勢(shì)阱可以將冷原子囚禁在四個(gè)金屬納米圓柱中間上方的長(zhǎng)350 nm、寬350 nm、高66 nm的周期性暗中空區(qū)域內(nèi),并且可以通過(guò)改變圓柱陣列的幾何參數(shù)來(lái)調(diào)整光學(xué)勢(shì)阱的空間大小與相對(duì)位置,方便對(duì)原子的操縱與控制。此外,討論了囚禁在光學(xué)勢(shì)阱中原子的自發(fā)輻射、瑞利散射與拉曼散射情況,并考慮原子的冷卻特性。在第三部分中,提出了一種基于亞波長(zhǎng)梯形介質(zhì)光柵的高帶寬超高反射率反射鏡方法。利用嚴(yán)格耦合波理論和有限元數(shù)值模擬方法研究了亞波長(zhǎng)梯形介質(zhì)光柵平面波入射情況下的反射特性,發(fā)現(xiàn)通過(guò)兩種方法得到的反射率曲線吻合得非常好。通過(guò)優(yōu)化結(jié)構(gòu)參數(shù),可以得到中心頻率約為1550 nm處,具有345 nm寬的高反射帶寬,且其反射率超過(guò)99.9%(Δλ/λ22%)。另外,通過(guò)調(diào)整結(jié)構(gòu)參數(shù),可以獲得反射帶寬為80 nm,對(duì)應(yīng)的反射率超過(guò)99.99%的反射鏡。光柵中存在的歸一化電場(chǎng)強(qiáng)度近場(chǎng)分布的駐波模式被用來(lái)解釋高反射率形成的原因。在第四部分中,提出了基于一種準(zhǔn)周期的亞波長(zhǎng)介質(zhì)光柵的反射聚焦方案。通過(guò)有限元數(shù)值模擬,我們發(fā)現(xiàn)當(dāng)光柵周期L=700 nm,光柵柵格寬度l1=525 nm時(shí),光柵柵格高度的分布符合一元二次曲線,當(dāng)中間層的厚度d=600 nm時(shí),可以獲得聚焦中心處強(qiáng)度高于周圍約5倍的反射聚焦效果。研究發(fā)現(xiàn)反射鏡的聚焦效果和反射光柵處的相位分布有著密切的關(guān)系,還討論了光柵的結(jié)構(gòu)參數(shù)對(duì)反射光柵處相位分布的影響。
[Abstract]:With the development and maturity of laser processing technology, material processing technology has been able to achieve nanoscale precision, which provides a condition for the study of optical properties of subwavelength structures. The subwavelength structure has attracted more and more attention because of its unique optical properties. Firstly, the research progress of the subwavelength metal structure and the subwavelength dielectric structure is introduced in this paper. The characteristics of surface plasma excitators are also discussed. Secondly, the near field optical properties of two dimensional periodic nanometallic cylindrical structures are discussed, and the influence of structural parameters on the near field dark space mode is discussed. The possibility of atom trapping is discussed by combining van der Waals potential and spontaneous emission. Then, a high bandwidth and ultra-high reflectivity reflector based on sub-wavelength trapezoidal dielectric grating is proposed. Finally, a reflection focusing method using subwavelength dielectric grating is proposed, and the influence of structure parameters on the mirror phase is discussed. In the second part. A scheme of realizing two-dimensional atomic optical lattice using metal cylindrical array is proposed. The surface plasmon characteristics are studied by means of finite element numerical simulation, and the near-field coupling of adjacent cylinders is considered. The effect of optical potential on cold atom and van der Waals potential is analyzed. The distribution of total potential field and the dependence of center position of potential well with structural parameters are discussed. The optical potential well formed by metal nanometers can trap cold atoms in a periodic dark hollow region of 350 nm in length, 350 nm in width and 66 nm in height above the middle of four metal nanometers. The spatial size and relative position of the optical potential well can be adjusted by changing the geometric parameters of the cylindrical array to facilitate the manipulation and control of atoms. In addition, the spontaneous emission of atoms trapped in the optical potential well is discussed. Rayleigh scattering and Raman scattering, taking into account the cooling properties of atoms. In the third part. A high bandwidth ultra-high reflectance reflector method based on subwavelength trapezoidal dielectric grating is proposed. The plane wave incidence of subwavelength trapezoidal dielectric grating is studied by using strictly coupled wave theory and finite element numerical simulation method. The reflection properties of. It is found that the reflectivity curves obtained by the two methods are in good agreement with each other. By optimizing the structural parameters, the center frequency is about 1550 nm and the high reflectance bandwidth of 345 nm is obtained. Moreover, the reflectivity is more than 99.9 (螖 位 / 位 22). In addition, by adjusting the structural parameters, the reflection bandwidth of 80 nm can be obtained. A mirror with a reflectivity of more than 99.99%. The standing wave mode of the near-field distribution of normalized electric field intensity in the grating is used to explain the formation of high reflectivity. In part 4th. A reflection focusing scheme based on a quasi-periodic subwavelength dielectric grating is proposed. By finite element numerical simulation, we find that when the grating period is 700 nm. When the width of grating grid is l1 ~ 525nm, the raster height distribution accords with the quadratic curve, and when the thickness of the middle layer is 600 nm. It is found that the focusing effect of the mirror is closely related to the phase distribution of the reflection grating. The influence of the structure parameters on the phase distribution of the reflective grating is also discussed.
【學(xué)位授予單位】：江蘇大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN25;TH74

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