本文選題：耦合模理論　切入點(diǎn)：布拉格光柵　出處：《北京交通大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：模分復(fù)用是繼時(shí)分復(fù)用和波分復(fù)用等復(fù)用技術(shù)后的一種新型復(fù)用技術(shù),利用不同的模式傳輸信息,能夠極大地提高通信系統(tǒng)的容量。目前的研究現(xiàn)狀表明,實(shí)現(xiàn)模分復(fù)用的方式可能有多種,而有效生成高階矢量模成為了一些模式復(fù)用方法的關(guān)鍵因素�；谝陨涎芯勘尘�,本文提出了一種基于FBG(Fiber Bragg Grating)實(shí)現(xiàn)基模耦合到高階矢量模的新方法。應(yīng)用閃耀光纖光柵全矢量復(fù)模理論,研究了基于階躍型少模光纖和環(huán)形少模光纖的單側(cè)紫外光曝光寫入的FBG,實(shí)現(xiàn)了基模到高階矢量模(TE01、TM01和HE21)的耦合。分析了紫外光指數(shù)分布的衰減因子α、光柵幅度函數(shù)χ以及光柵長(zhǎng)度等因素對(duì)耦合特性的影響。對(duì)于基于階躍型少模光纖的FBG,研究表明,通過(guò)合理調(diào)節(jié)光柵的各個(gè)參數(shù),可以實(shí)現(xiàn)高效的矢量模式耦合;但是階躍型少模光纖無(wú)法將LP111模式群的簡(jiǎn)并矢量模進(jìn)行有效分離。對(duì)于基于環(huán)形少模光纖的FBG,研究表明,由于此環(huán)形光纖結(jié)構(gòu)能夠打破LP111模式群中矢量模式的簡(jiǎn)并性,高階矢量模間的模式有效折射率差達(dá)到1.8×10-4,可以在不同反射波長(zhǎng)處實(shí)現(xiàn)高效耦合。耦合系數(shù)和反射率隨紫外光指數(shù)分布的衰減因子α的變化存在優(yōu)化極值點(diǎn)。隨著光柵幅度函數(shù),值的增大,反射率會(huì)增大,反射峰位置向長(zhǎng)波長(zhǎng)方向移動(dòng),同時(shí)反射譜會(huì)變寬。在χ值增大的過(guò)程中,TE01模和HE21 s模會(huì)發(fā)生相互作用,使反射率下降,且兩者的反射峰相對(duì)位置會(huì)發(fā)生互換。本論文提出的實(shí)現(xiàn)基模耦合到高階矢量模的FBG,為光纖中高階矢量模式的生成提供了新的技術(shù)手段,在模分復(fù)用技術(shù)研究領(lǐng)域具有重要應(yīng)用價(jià)值。
[Abstract]:Module division multiplexing is a new type of multiplexing technology after time division multiplexing (TDM) and wavelength division multiplexing (WDM). Using different modes to transmit information can greatly improve the capacity of communication system. There may be many ways to realize module division multiplexing, and the efficient generation of high-order vector modules has become the key factor of some pattern multiplexing methods. In this paper, a new method based on FBG(Fiber Bragg Gratingis proposed to realize the coupling of fundamental mode to high order vector mode, and the blazed fiber grating full vector complex mode theory is applied. The FBGs written by single-side ultraviolet light exposure based on step less mode fiber and ring less mode fiber are studied. The coupling of base mode to higher order vector mode TE01 and HE21) is realized. The attenuation factor 偽 and the grating amplitude function of the exponential distribution of ultraviolet light are analyzed. The effect of the number 蠂 and the grating length on the coupling characteristics. For the FBG based on the step less mode fiber, it is shown that, The efficient vector mode coupling can be realized by adjusting the parameters of the grating reasonably, but the degenerate vector mode of the LP111 mode group can not be effectively separated by the step less mode fiber. Because this ring fiber structure can break the degeneracy of vector mode in LP111 mode group, The difference of effective refractive index between higher order vector modes reaches 1.8 脳 10 ~ (-4), which can achieve high efficiency coupling at different reflectance wavelengths. The variation of coupling coefficient and reflectivity with the attenuation factor 偽 of ultraviolet light exponent distribution is optimized. With the increase of 蠂 value, the reflectivity will increase, the position of the reflection peak will move to the direction of long wavelength, and the reflection spectrum will become wider. In the process of increasing 蠂 value, there will be interaction between the HE21 s mode and the TE01 mode, which will decrease the reflectivity. The relative position of the two peaks will be interchangeable. In this paper, the FBGs which realize the coupling of the base mode to the higher-order vector mode provide a new technique for the generation of high-order vector mode in optical fiber. It has important application value in the research field of module division multiplexing technology.
【學(xué)位授予單位】：北京交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN253

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本文編號(hào)：1572028