本文選題：光學(xué)非線(xiàn)性 + 摻鉺光纖��； 參考：《國(guó)防科學(xué)技術(shù)大學(xué)》2015年碩士論文

【摘要】：摻鉺光纖動(dòng)態(tài)光柵具有超窄帶寬、實(shí)時(shí)光控與自適應(yīng)特性,在光纖激光器、光纖信息技術(shù)等領(lǐng)域有重要應(yīng)用價(jià)值,從而引起了廣泛的關(guān)注。在傳統(tǒng)的應(yīng)用中需要兩束同頻、同偏振光場(chǎng)在摻鉺光纖中形成駐波,通過(guò)飽和吸收效應(yīng)形成吸收型各向同性動(dòng)態(tài)光柵。實(shí)際應(yīng)用中存在著光柵效率較低,易受偏振態(tài)影響等問(wèn)題,從而影響光纖器件性能、造成光纖激光器不穩(wěn)定。近年來(lái)的報(bào)道表明:增益型動(dòng)態(tài)光柵可能有更高的光柵效率。同時(shí)本課題組獨(dú)立發(fā)現(xiàn)了利用法拉第旋鏡,可使兩束偏振正交光場(chǎng)在普通非雙折射摻鉺光纖中產(chǎn)生各向異性動(dòng)態(tài)光柵的新現(xiàn)象,其產(chǎn)生機(jī)理值得深入研究。本文將針對(duì)這兩種動(dòng)態(tài)光柵展開(kāi)研究。同時(shí)在光頻率調(diào)制法的基礎(chǔ)上發(fā)展了“強(qiáng)弱光交替”法,可用于測(cè)量動(dòng)態(tài)光柵的瞬態(tài)特性。本文的研究?jī)?nèi)容和結(jié)果包括:(1)在考慮泵浦光的情況下,推導(dǎo)出摻鉺光纖中統(tǒng)一的四波混合非線(xiàn)性微分方程,可用于描述泵浦或非泵浦下的動(dòng)態(tài)光柵特性。對(duì)統(tǒng)一的非線(xiàn)性微分方程進(jìn)行了數(shù)值分析,發(fā)現(xiàn)了在一定強(qiáng)度的泵浦光下?lián)姐s光纖中可同時(shí)存在增益型和吸收型動(dòng)態(tài)光柵,并在實(shí)驗(yàn)中測(cè)到這一現(xiàn)象。對(duì)各向同性動(dòng)態(tài)光柵的特性隨寫(xiě)入光強(qiáng)、泵浦光強(qiáng)變化的規(guī)律進(jìn)行了系統(tǒng)的實(shí)驗(yàn)研究并與仿真結(jié)果對(duì)比,結(jié)果表明:新的非線(xiàn)性微分方程在一定程度上可用于描述增益型動(dòng)態(tài)光柵的反射譜特性。(2)在光頻率調(diào)制法的基礎(chǔ)上,提出將“強(qiáng)弱光交替”法用于測(cè)量動(dòng)態(tài)光柵特征時(shí)間。對(duì)此方法進(jìn)行測(cè)試,測(cè)得的數(shù)據(jù)與理論相符,驗(yàn)證了此方法的有效性。(3)結(jié)合光頻率調(diào)制法和“強(qiáng)弱光交替法”,將各向異性動(dòng)態(tài)光柵與各向同性動(dòng)態(tài)光柵進(jìn)行了系統(tǒng)的對(duì)比研究。實(shí)驗(yàn)結(jié)果表明,各向異性動(dòng)態(tài)光柵在特征時(shí)間、帶寬方面與各向同性動(dòng)態(tài)光柵相似,但其反射譜的最大相對(duì)變化約為2.5%,比各向同性動(dòng)態(tài)光柵低約1/2。
[Abstract]:Erbium-doped fiber dynamic gratings (EDGs) have been widely used in many fields such as fiber lasers, fiber information technology and so on, because of their ultra-narrow bandwidth, real-time optical control and adaptive characteristics. In the traditional application, two beams of the same frequency are needed, the same polarized light field forms standing wave in erbium-doped fiber, and the absorption isotropic dynamic grating is formed by saturated absorption effect. In practical application, there are some problems such as low efficiency of grating and easy to be affected by polarization state, which affects the performance of fiber devices and results in instability of fiber laser. It has been reported in recent years that the gain dynamic grating may have higher grating efficiency. At the same time, our team has independently discovered that using Faraday rotating mirror can make two beams of polarization orthogonal light field produce anisotropic dynamic grating in ordinary non-birefringent erbium-doped fiber, and its mechanism is worthy of further study. In this paper, the two kinds of dynamic gratings will be studied. At the same time, based on the optical frequency modulation method, the "strong and weak light alternating" method is developed, which can be used to measure the transient characteristics of the dynamic grating. The research contents and results of this paper include: (1) under the consideration of pump light, a unified four-wave nonlinear differential equation of mixing in erbium-doped fiber is derived, which can be used to describe the dynamic grating characteristics under pump or non-pumping. The unified nonlinear differential equations are numerically analyzed. It is found that there are both gain and absorption dynamic gratings in erbium-doped fiber under a certain intensity of pumping light, and this phenomenon is measured in experiments. The characteristics of the isotropic dynamic grating with the writing intensity and the pump intensity are studied experimentally and compared with the simulation results. The results show that the new nonlinear differential equation can be used to describe the reflectance spectrum characteristics of the gain dynamic grating to some extent. On the basis of the optical frequency modulation method, the "strong and weak light alternating light" method is proposed to measure the characteristic time of the dynamic grating. This method is tested and the measured data are in agreement with the theory. The validity of the method is verified by combining the optical frequency modulation method with the "strong and weak light alternating method". The comparison between anisotropic dynamic grating and isotropic dynamic grating is carried out. The experimental results show that the anisotropic dynamic grating is similar to the isotropic dynamic grating in characteristic time and bandwidth, but the maximum relative variation of the reflectance spectrum is about 2.5, which is about 1 / 2 lower than that of the isotropic dynamic grating.
【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(lèi)號(hào)】：TN25

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本文編號(hào)：1785861