本文選題：超熒光 + 放大自發(fā)輻射��； 參考：《國(guó)防科學(xué)技術(shù)大學(xué)》2015年碩士論文

【摘要】：超熒光光纖光源是利用稀土元素?fù)诫s光纖中的放大自發(fā)輻射(ASE)過(guò)程獲得寬譜輸出的光纖光源,隨著輸出功率的不斷提升,在不同領(lǐng)域得到廣泛應(yīng)用。分布式側(cè)面耦合包層泵浦(DSCCP)基于倏逝場(chǎng)耦合技術(shù),實(shí)現(xiàn)泵浦功率的分布耦合,有望實(shí)現(xiàn)超熒光輸出功率的進(jìn)一步提升。本文提出基于DSCCP光纖的超熒光光源設(shè)計(jì)方案,并建立基于DSCCP光纖的超熒光光源數(shù)值模型,分析其輸出特性和功率提升限制因素,并通過(guò)優(yōu)化實(shí)驗(yàn)設(shè)計(jì),獲得高功率輸出的全光纖超熒光光源。論文主要工作如下:1.基于DSCCP光纖的超熒光光源理論研究和數(shù)值仿真根據(jù)DSCCP光纖的簡(jiǎn)化的泵浦光耦合傳輸模型,結(jié)合速率方程理論,建立DSCCP超熒光光纖光源數(shù)值模型,該模型能夠較好地描述泵浦光和信號(hào)光演變的物理過(guò)程;根據(jù)最大總增益等于腔內(nèi)損耗這一寄生振蕩判定條件,建立寄生振蕩閾值計(jì)算模型;利用數(shù)值方法求解建立的超熒光光纖光源速率方程理論模型,研究其輸出特性和限制功率提升的因素。理論研究發(fā)現(xiàn):光纖輸出端面的光纖反饋是限制功率提升的主要因素;此外,增益光纖長(zhǎng)度會(huì)影響整個(gè)光纖的增益狀態(tài),增大光纖長(zhǎng)度會(huì)導(dǎo)致短波部分的ASE被重吸收,在某一光纖長(zhǎng)度下,寄生振蕩波長(zhǎng)出現(xiàn)由短波1045 nm向1070 nm的大幅轉(zhuǎn)換,而這一光纖長(zhǎng)度下的ASE輸出功率最大,我們將其定義為最優(yōu)光纖長(zhǎng)度,該最優(yōu)長(zhǎng)度與稀土離子摻雜濃度成反比關(guān)系;較大的纖芯包層比有益于抑制寄生振蕩的出現(xiàn),可以一定程度上提升ASE最大輸出功率。2.基于DSCCP光纖的高功率超熒光光源實(shí)驗(yàn)研究搭建30/250-250μm超熒光光纖光源,輸出ASE功率達(dá)百瓦量級(jí),驗(yàn)證了于DSCCP光纖在高功率超熒光光源上應(yīng)用的可行性,并實(shí)現(xiàn)了全光纖結(jié)構(gòu)。通過(guò)優(yōu)化斜角切割參數(shù),獲得7.5°的傾斜輸出端面,鏡面區(qū)域?qū)挾冗_(dá)到光纖直徑的4/5,使得粗糙區(qū)域與纖芯距離足夠大,保證了纖芯端面光學(xué)平整。在此基礎(chǔ)上,進(jìn)一步將超熒光輸出功率提升到135 W,斜率效率高達(dá)79.8%,前后向光譜帶寬(FHWM)分別為34 nm和32.8 nm,一分鐘內(nèi)的功率波動(dòng)不大于±1.4%。同時(shí),實(shí)驗(yàn)研究了超熒光光纖光源輸出功率與增益光纖長(zhǎng)度的關(guān)系,驗(yàn)證了理論上最優(yōu)增益光纖長(zhǎng)度的存在,在光纖長(zhǎng)度為7.3 m時(shí),獲得了最大功率輸出186 W,這是目前為止單級(jí)超熒光光纖光源的最高輸出功率。
[Abstract]:Superfluorescent fiber source is a kind of optical fiber light source which uses amplified spontaneous emission (ASE) process in rare-earth doped fiber to obtain wide-spectrum output. With the increasing of output power, it has been widely used in different fields. Distributed side-coupled cladding pump (DSCCP) is based on evanescent field coupling technology to realize the distributed coupling of pump power, which is expected to achieve further enhancement of superfluorescence output power. In this paper, a design scheme of superfluorescent light source based on DSCCP fiber is proposed, and a numerical model of superfluorescent light source based on DSCCP fiber is established. The output characteristics and power rise limiting factors are analyzed, and the experimental design is optimized. An all-fiber superfluorescent light source with high power output is obtained. The main work of this paper is as follows: 1. Theoretical research and numerical simulation of superfluorescent light source based on DSCCP fiber A numerical model of DSCCP superfluorescent fiber source is established according to the simplified pump light coupling transmission model of DSCCP fiber and the theory of rate equation. The model can describe the physical process of the evolution of pump light and signal light, and establish a model for calculating the threshold of parasitic oscillation according to the condition that the maximum total gain is equal to the loss in the cavity. The theoretical model of the rate equation of superfluorescent fiber source is solved by numerical method. The output characteristics and the factors limiting the power increase are studied. It is found that the fiber feedback at the output end of the fiber is the main factor limiting the power increase, in addition, the gain fiber length will affect the gain state of the whole fiber, and the increase of the fiber length will lead to the reabsorption of the ASE in the shortwave part. A large conversion of the parasitic oscillation wavelength from 1045 nm to 1070 nm occurs at a certain fiber length, and the output power of the optical fiber is the largest, which is defined as the optimal fiber length. The optimum length is inversely proportional to the doping concentration of rare earth ions, and the larger core-cladding ratio is beneficial to the suppression of parasitic oscillation, and the maximum output power of ASE can be increased to a certain extent by .2. The experimental study of high power superfluorescent light source based on DSCCP fiber is carried out, and the output ASE power is 100 watts. The feasibility of DSCCP fiber applied in high power superfluorescent light source is verified, and the all-fiber structure is realized. By optimizing the angle cutting parameters, an inclined output end face of 7.5 擄is obtained. The width of the mirror area reaches 4 / 5 of the diameter of the fiber, which makes the distance between the rough area and the core large enough to ensure the optical leveling of the core end face. On this basis, the superfluorescence output power is further raised to 135 W, the slope efficiency is as high as 79.8, the forward and backward spectral bandwidth (FHWM) is 34 nm and 32.8 nm, respectively, and the power fluctuation within one minute is less than 鹵1.4 nm. At the same time, the relationship between the output power and the gain fiber length of the superfluorescent fiber source is experimentally studied, and the existence of the theoretical optimal gain fiber length is verified. When the fiber length is 7.3 m, The maximum output power is 186 W, which is the highest output power of single stage superfluorescent fiber source so far.
【學(xué)位授予單位】：國(guó)防科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TN253

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本文編號(hào)：2057943