本文關(guān)鍵詞： 二元光學(xué) 嚴(yán)格耦合波理論 亞波長(zhǎng)光柵 自支撐結(jié)構(gòu) 太赫茲偶數(shù)分束器 遺傳算法　出處：《深圳大學(xué)》2016年碩士論文　論文類型：學(xué)位論文

【摘要】：太赫茲功能器件作為太赫茲技術(shù)應(yīng)用中的關(guān)鍵和基礎(chǔ),目前相關(guān)的研究主要集中在以光子晶體、表面等離子體、超穎光柵、石墨烯等復(fù)雜結(jié)構(gòu)實(shí)現(xiàn)太赫茲的分束、濾波、偏振控制等方面,復(fù)雜的結(jié)構(gòu)導(dǎo)致制作困難,成本較高,實(shí)際效果不理想。所以,結(jié)構(gòu)簡(jiǎn)單、功能優(yōu)異的太赫茲功能器件的研究極具科學(xué)意義。本文在實(shí)驗(yàn)室長(zhǎng)期二元光學(xué)器件研究的基礎(chǔ)上,將嚴(yán)格耦合波理論與遺傳算法相結(jié)合,提出并設(shè)計(jì)了基于自支撐簡(jiǎn)單周期結(jié)構(gòu)的太赫茲偶數(shù)分束器,實(shí)現(xiàn)高衍射效率、高均勻性、高零級(jí)抑制效果,同時(shí)簡(jiǎn)單結(jié)構(gòu)的應(yīng)用極大地降低了制作難度和成本,可使太赫茲功能器件進(jìn)一步實(shí)用化。目前國(guó)內(nèi)外基于自支撐簡(jiǎn)單周期結(jié)構(gòu)的二元光柵實(shí)現(xiàn)太赫茲偶數(shù)分束的研究未見報(bào)道。本文的主要研究?jī)?nèi)容如下:1.以嚴(yán)格耦合波理論為基礎(chǔ),建立平面波入射自支撐簡(jiǎn)單周期結(jié)構(gòu)條件下太赫茲分束器各級(jí)衍射效率與自支撐結(jié)構(gòu)參數(shù)(光柵周期d、光柵占空比f(wàn)、光柵深度h、光柵材料折射率n)的映射關(guān)系;為自支撐亞波長(zhǎng)光柵太赫茲分束器的衍射效率和均勻性設(shè)置恰當(dāng)?shù)脑u(píng)價(jià)函數(shù),結(jié)合遺傳優(yōu)化算法,根據(jù)優(yōu)化結(jié)果不斷調(diào)整評(píng)價(jià)函數(shù)各項(xiàng)權(quán)重因子,給出合適的權(quán)重因子。2.綜合運(yùn)用嚴(yán)格耦合波理論與遺傳算法,基于自支撐簡(jiǎn)單周期結(jié)構(gòu)的二元光柵,設(shè)計(jì)了分束數(shù)為二、四、六的三款偶數(shù)硅基太赫茲分束器。最佳分束效果為:高階總衍射效率能夠達(dá)到99.14%,零級(jí)透射率抑制在0.188%以內(nèi),均勻性誤差控制在6.16×10-16以內(nèi)。3.分析了光柵結(jié)構(gòu)參數(shù)的制作誤差和入射光參數(shù)的偏差對(duì)自支撐亞波長(zhǎng)光柵偶數(shù)分束器分束性能的影響,給出了分束器光柵結(jié)構(gòu)參數(shù)和入射光參數(shù)對(duì)分束效果的影響規(guī)律,該工作對(duì)于所設(shè)計(jì)分束器的制作和測(cè)試有一定的指導(dǎo)意義;對(duì)所設(shè)計(jì)的分束器進(jìn)行結(jié)構(gòu)參數(shù)公差分析,給出了最佳制作參數(shù),該工作可以指導(dǎo)自支撐亞波長(zhǎng)光柵太赫茲偶數(shù)分束器的實(shí)際制作。4.用硅基材料制作了工作波長(zhǎng)為118.83μm的自支撐亞波長(zhǎng)光柵太赫茲四分束器,分析了實(shí)際制作誤差的原因,并給出了相應(yīng)的解決辦法。本文提出并設(shè)計(jì)了基于自支撐二元簡(jiǎn)單周期結(jié)構(gòu)的亞波長(zhǎng)光柵的太赫茲偶數(shù)分束器,結(jié)合矢量分析理論與遺傳優(yōu)化算法設(shè)計(jì)了二、四、六三款偶數(shù)分束器,突破了傳統(tǒng)標(biāo)量方法設(shè)計(jì)的局限性,有效地抑制了零級(jí)衍射;本文所設(shè)計(jì)和制作的太赫茲偶數(shù)分束器由于結(jié)構(gòu)簡(jiǎn)單、功能可擴(kuò)展、制作方便,可望在未來(lái)太赫茲通訊與成像系統(tǒng)中獲得應(yīng)用。
[Abstract]:Terahertz functional devices are the key and foundation of terahertz technology application. At present, the related research mainly focuses on the realization of terahertz beam splitting and filtering with complex structures such as photonic crystal, surface plasma, superglume grating, graphene and so on. In polarization control and other aspects, the complicated structure leads to the difficulty of making, the high cost, and the actual effect is not ideal. Therefore, the structure is simple, The research of terahertz functional devices with excellent function is of great scientific significance. In this paper, strict coupled wave theory is combined with genetic algorithm on the basis of long-term binary optical device research in laboratory. A terahertz even-number beam splitter based on self-supporting simple periodic structure is proposed and designed to achieve high diffraction efficiency, high uniformity and high zero order suppression. The application of simple structure greatly reduces the fabrication difficulty and cost. It can make THz functional devices more practical. At present, there is no report on the realization of terahertz even-number beam splitting based on self-supporting simple periodic grating at home and abroad. The main contents of this paper are as follows: 1. Strictly coupled. Based on the theory of combined wave, The mapping relationship between the diffraction efficiency of terahertz beam splitter and the parameters of self-supporting structure (grating period d, grating duty cycle f, grating depth h, refractive index of grating material n) under the condition of simple periodic structure of incident plane wave is established. For the diffraction efficiency and uniformity of the self-supporting sub-wavelength grating terahertz beam splitter, the appropriate evaluation function is set up. Combined with genetic optimization algorithm, the weight factors of the evaluation function are continuously adjusted according to the optimization results. The appropriate weight factor is given. 2. Combining the strictly coupled wave theory and genetic algorithm, based on the binary grating with self-supporting simple periodic structure, the beam splitting number is designed to be two and four. The best beam splitting effect is that the total diffraction efficiency of higher order can reach 99.14 and the transmission of zero order is limited to 0.188%. The uniformity error is controlled within 6.16 脳 10 ~ (-16). 3. The effects of the fabrication error of grating structure parameters and the deviation of incident light parameters on the beam splitting performance of self-supporting sub-wavelength even number beam splitter are analyzed. The influence of beam splitter grating structure parameters and incident light parameters on beam splitting effect is given. The work is of guiding significance for the fabrication and testing of the designed beam splitter, and the structural parameter tolerance analysis of the designed beam splitter is carried out. The optimum fabrication parameters are given. This work can guide the practical fabrication of the self-supporting sub-wavelength grating terahertz even number splitter. Finally, the self-supporting sub-wavelength grating terahertz beam splitter with the working wavelength of 118.83 渭 m has been fabricated with silicon based material, and the self-supporting sub-wavelength grating terahertz beam splitter with the working wavelength of 118.83 渭 m has been fabricated. The causes of practical fabrication errors are analyzed, and the corresponding solutions are given. In this paper, a terahertz even number beam splitter for subwavelength grating based on self-supporting binary simple periodic structure is proposed and designed. Combined with vector analysis theory and genetic optimization algorithm, two, four and six even-number beam splitters are designed, which break through the limitation of traditional scalar method and effectively suppress zero-order diffraction. The terahertz even-number beam splitter designed and fabricated in this paper is expected to be used in terahertz communication and imaging systems in the future due to its simple structure, extensible function and convenient fabrication.
【學(xué)位授予單位】：深圳大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：TN25

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