發(fā)布時間：2018-04-21 15:35

  本文選題：光子晶體 + 表面波��； 參考：《電子科技大學》2014年碩士論文

【摘要】：自由空間光通信是指以激光作為信息載體,在大氣中傳輸信息的通信系統(tǒng)。光通信以其周期短、成本低、抗電磁能力強、保密性好等優(yōu)點而被人們廣泛關注。本文針對光通信系統(tǒng)中的激光準直與耦合技術進行研究,利用光子晶體對激光發(fā)散角進行準直,通過光學軟件仿真對所得到的準直結果進行驗證;設計出超寬帶色散平坦的光子晶體光纖以提高光通信系統(tǒng)中的光傳輸效率,對光子晶體光纖和單模光纖的耦合特性進行研究分析。光子晶體是一種人工制造的光子帶隙材料,這是由于介電常數周期性改變使得光產生折射性的周期性分布。光子禁帶的產生使得有關光子晶體的許多應用都是依賴于其禁帶的頻率范圍,這為光控制提供了一種新的機理,受到人們的廣泛關注。本論文所做的主要工作包括:1.簡述光通信原理以及激光準直與耦合的幾種方法,確定文章采用光子晶體材料進行研究,并簡述光子晶體的發(fā)展歷程及其在光通信中的應用。介紹光子晶體的理論研究中主要的方法——平面波展開法、傳輸矩陣法及時域有限差分法,以及用光學軟件對光子晶體仿真所用到的有限元法。2.利用表面波作用對傳統(tǒng)二維光子晶體結構進行改進,考察激光束的準直效果。與傳統(tǒng)的二維光子晶體結構對比發(fā)現具有表面結構的光子晶體取得較好的準直角,并且利用遠場傳輸分布特性直觀的分析準直效果。表面結構的色散曲線及二維光子晶體的能帶曲線圖通過平面波展開法計算求出。通過計算得出表面模式的準直波頻率不在光子禁帶范圍內,并且利用軟件對準直結果進行仿真,結果可以明確的看出具有表面結構的新型光子晶體準直效果優(yōu)于傳統(tǒng)的光子晶體準直。3.設計超平坦色散的光子晶體光纖,減小光在光纖中傳輸時的碼間串擾。分析影響色散曲線的主要因素,得出的結論是包層空氣孔半徑和孔間距對色散產生了較大影響,對影響色散曲線的結構參數進行改變,優(yōu)化光子晶體光纖的色散曲線,得出了大波長范圍內的色散平坦曲線。分析影響光子晶體光纖與單模光纖耦合的因素,并將文中設計的超平坦色散光子晶體光纖與單模進行耦合,計算耦合損耗。
[Abstract]:Free space optical communication is a communication system which uses laser as information carrier and transmits information in atmosphere. Optical communication is widely concerned because of its short period, low cost, strong electromagnetic resistance and good confidentiality. In this paper, the laser collimation and coupling technology in optical communication system are studied, the laser divergence angle is collimated by photonic crystal, and the collimation result is verified by optical software simulation. The photonic crystal fiber with UWB dispersion flat is designed to improve the optical transmission efficiency in optical communication system. The coupling characteristics of photonic crystal fiber and single-mode fiber are studied and analyzed. Photonic crystal is a kind of artificial photonic bandgap material, which is caused by periodic change of dielectric constant to produce periodic distribution of light refraction. The generation of photonic bandgap makes many applications of photonic crystals depend on the frequency range of photonic crystals, which provides a new mechanism for optical control. The main work of this paper includes 1: 1. This paper introduces the principle of optical communication and several methods of laser collimation and coupling. It is determined that the photonic crystal material is used to study it. The development of photonic crystal and its application in optical communication are also briefly described. The main theoretical methods of photonic crystal are plane wave expansion method, transfer matrix method and finite-difference time-domain method, and the finite element method .2which is used to simulate photonic crystal with optical software. The conventional two-dimensional photonic crystal structure is improved by surface wave interaction to investigate the collimation effect of laser beam. Compared with the traditional two-dimensional photonic crystal structure, it is found that the photonic crystal with surface structure has a good quasi-right angle, and the collimation effect is analyzed intuitively by using the far-field transmission distribution characteristics. The dispersion curve of surface structure and the energy band curve of two-dimensional photonic crystal are calculated by plane wave expansion method. It is found that the collimation frequency of the surface mode is not within the range of photonic band gap, and the collimation results are simulated by software. The results show that the collimation effect of new photonic crystal with surface structure is better than that of traditional photonic crystal collimation. A photonic crystal fiber with ultra-flat dispersion is designed to reduce the intersymbol crosstalk when light is transmitted in the fiber. The main factors affecting dispersion curves are analyzed. The conclusion is that the radius of air holes and the spacing of holes in cladding have a great influence on dispersion. The structure parameters affecting dispersion curves are changed and the dispersion curves of photonic crystal fibers are optimized. The dispersion flatness curves in a wide wavelength range are obtained. The factors influencing the coupling between photonic crystal fiber and single-mode fiber are analyzed. The ultra-flat dispersive photonic crystal fiber is coupled with single mode and the coupling loss is calculated.
【學位授予單位】：電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN929.1

【參考文獻】

相關期刊論文 前1條

1 李鵬;張全;沈詩哲;葛劍虹;;柱狀楔形微透鏡光纖與半導體激光器耦合效率研究[J];光學儀器;2006年03期

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本文編號：1783040