本文選題：窄帶選模　切入點：回音壁模式　出處：《南京郵電大學》2016年碩士論文　論文類型：學位論文

【摘要】：隨著光通信、光學傳感、軍工和醫(yī)療等領(lǐng)域的發(fā)展,高性能光纖光源成為研究熱點。窄線寬光纖激光器作為高性能光纖光源重要的研究方向,由于其具有線寬窄、波長靈活、設(shè)備小巧以及可實現(xiàn)高功率輸出等特性,成為光纖傳感、雷達和光纖通信等領(lǐng)域的重點研究對象,對光纖激光器的窄帶選模技術(shù)提出了新的要求�；匾舯谀Ｊ焦鈱W微腔由于其高品質(zhì)因數(shù)、小模式體積、低損耗和低成本等優(yōu)點,成為一種理想的窄帶濾波器。本文針對回音壁模式微球腔在窄帶激光選模方面的性能展開相關(guān)研究,介紹了回音壁模式微腔的起源、發(fā)展、分類和應(yīng)用。論文首先闡述了幾種主要的微腔耦合方法和理論模型。接著,本文利用FDTD軟件仿真分析了回音壁模式均勻介質(zhì)微球腔與拉錐光纖的耦合過程。為改進回音壁模式微球腔的窄帶選模能力,本文提出了兩種新型的回音壁模式微球腔結(jié)構(gòu):其一,提出了一種均勻介質(zhì)雙微球級聯(lián)結(jié)構(gòu),仿真結(jié)果表明,均勻介質(zhì)雙微球-拉錐光纖耦合系統(tǒng)較均勻介質(zhì)單微球-拉錐光纖耦合系統(tǒng)降低了輸出共振譜諧振峰的峰值透射率,提高了邊模抑制比,壓縮了諧振峰的線寬,從而提高了整個系統(tǒng)的窄帶選模能力。其二,提出了一種雙層介質(zhì)結(jié)構(gòu)回音壁模式微球,即在純SiO2均勻介質(zhì)微球表面鍍高折射率介質(zhì)膜層,仿真結(jié)果表明,當均勻介質(zhì)微球表面鍍層厚度為100 nm、折射率為2.4時,鍍膜微球-拉錐光纖耦合系統(tǒng)較均勻介質(zhì)微球-拉錐光纖耦合系統(tǒng)降低了輸出共振譜諧振峰的峰值透射率,提高了邊模抑制比,壓縮了諧振峰的線寬,從而提高了系統(tǒng)的窄帶選模性能;同時,該系統(tǒng)還提高了光場分布中的最大能量密度,降低了微腔的模式體積。此外,本文還對仿真所使用的鍍膜微球的膜層厚度進行了優(yōu)化,結(jié)果表明,當膜層厚度約為180 nm時,系統(tǒng)性能最佳,邊模抑制比達到最大值,線寬得到進一步壓縮,最大能量密度大幅提升,微球腔的模式體積更小。因此,本文提出的兩種改進方法均對均勻介質(zhì)微球的窄帶選模性能有所提升,為實際應(yīng)用提供了科學依據(jù)和理論指導。最后,本文設(shè)計并搭建了回音壁模式微球腔-拉錐光纖耦合實驗系統(tǒng),并通過實驗得到了窄帶回音壁模共振譜,自由光譜范圍約為1.32 nm,線寬約為0.8 pm,Q值高達2.0×106。實驗表明,回音壁模式微球腔應(yīng)用于窄帶選模和光學濾波領(lǐng)域具有可行性和高效性。
[Abstract]:With the development of optical communication, optical sensing, military industry and medical treatment, high performance optical fiber light source has become a research hotspot. Narrow linewidth fiber laser is an important research direction of high performance optical fiber light source, because of its narrow line width and flexible wavelength. Because of its small size and the ability to achieve high power output, it has become an important research object in the fields of optical fiber sensing, radar and optical fiber communication. A new requirement for narrowband mode selection of fiber lasers is put forward. Due to its advantages of high quality factor, small mode volume, low loss and low cost, echo wall mode optical microcavity has many advantages, such as high quality factor, small mode volume, low loss and low cost. It is an ideal narrowband filter. In this paper, the origin and development of echo-mode microsphere cavity in narrowband laser mode selection are introduced. Classification and application. Firstly, several main methods and theoretical models of microcavity coupling are introduced. In this paper, the coupling process of homogenous dielectric microsphere cavity with tapered fiber is simulated by FDTD software. In order to improve the narrowband mode selection ability of echo wall mode microsphere cavity, In this paper, two new types of echo-wall microsphere cavity structures are proposed. First, a uniform dielectric double-microsphere cascade structure is proposed. The simulation results show that, The double microsphere tapered fiber coupling system in uniform medium reduces the peak transmittance of the resonant peak of the output resonance spectrum, increases the edge-mode rejection ratio, and compresses the linewidth of the resonant peak, compared with the uniform dielectric single-microsphere tapered fiber coupling system. Therefore, the narrow band mode selection ability of the whole system is improved. Secondly, a double-layer dielectric structure echo wall mode microsphere is proposed, which is coated with high refractive index dielectric film on the surface of pure SiO2 homogeneous dielectric microsphere. The simulation results show that, When the coating thickness and refractive index of uniform dielectric microspheres are 100 nm and 2.4, the peak transmittance of the resonant peak of the output resonance spectrum is reduced in the coated microsphere tapered fiber coupling system compared with the uniform dielectric microsphere tapered fiber coupling system. The edge-mode rejection ratio is increased, the linewidth of the resonant peak is compressed, and the narrowband mode selection performance of the system is improved. At the same time, the maximum energy density in the optical field distribution is increased, and the mode volume of the microcavity is reduced. The film thickness of the coating microspheres used in the simulation is optimized. The results show that when the film thickness is about 180 nm, the system performance is the best, the side mode rejection ratio reaches the maximum, and the line width is further compressed. The maximum energy density is greatly increased, and the mode volume of the microsphere cavity is much smaller. Therefore, the two improved methods proposed in this paper have improved the narrowband mode selection performance of the homogeneous dielectric microspheres, and provided scientific basis and theoretical guidance for practical application. In this paper, an experimental system of microsphere cavity and tapered fiber coupling with echo wall mode is designed and built. The resonant spectrum of narrow band echo wall is obtained by experiments. The free spectrum range is about 1.32 nm, and the line width is about 0.8 pmQ as high as 2.0 脳 106. The microsphere cavity with echo wall mode is feasible and efficient in narrow band mode selection and optical filtering.
【學位授予單位】：南京郵電大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TN24

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1 呂宏春;基于回音壁模式微腔的窄帶激光選模技術(shù)研究[D];南京郵電大學;2016年

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本文編號：1598467