本文選題：受激布里淵散射 + 微弱信號放大��； 參考：《哈爾濱工業(yè)大學》2016年碩士論文

【摘要】：微弱信號的探測一直是激光雷達和激光通信等領域的難點。對微弱光信號進行放大,是提高系統(tǒng)作用距離和靈敏度的有效手段。在各種光放大技術(shù)中,以光纖為增益介質(zhì)的基于受激布里淵散射(SBS)效應的光放大技術(shù)具備增益高、頻率選擇性好、系統(tǒng)可靠性強的優(yōu)點,在光放大領域有重要的應用價值。本文研究光纖布里淵放大參數(shù)(包括抽運光功率、信號光脈寬、光纖長度等)對SBS放大率和信噪比的影響規(guī)律,優(yōu)化參數(shù),以實現(xiàn)高增益、高信噪比的微弱回波信號放大。首先建立了含噪聲、用于數(shù)值研究的光纖中布里淵放大特性數(shù)學模型。利用此數(shù)值模型對單模光纖中的SBS過程進行數(shù)值模擬,通過單獨改變抽運光功率、信號光功率及脈寬、光纖長度等參數(shù),得出不同條件下放大率和信噪比的變化情況。研究表明:信號放大率隨抽運光功率增加而提高,隨信號光脈寬增加而提高,隨信號光功率增加而下降;信噪比隨抽運光功率增加而下降,隨信號光脈寬增加而提高,隨信號光功率增加而提高。實驗上,本文首先開展了非散射信號的布里淵放大實驗研究。采用連續(xù)抽運光放大脈沖信號光,以不同單模光纖作為SBS介質(zhì),改變實驗中抽運光、信號光、光纖參數(shù),研究其對單模光纖中SBS放大率和信噪比的影響。實驗對0.43μW信號光實現(xiàn)了107放大,信噪比為11dB。實驗研究與理論研究的放大率和信噪比的變化規(guī)律基本相符,確定了在弱抽運光功率情況下使用細芯徑光纖,強抽運光功率下使用普通單模光纖的實驗方法。在此基礎上,開展了散射信號的布里淵放大實驗研究,獲得了抽運光功率、信號光脈寬和光纖長度、芯徑對放大率和信噪比的影響規(guī)律。通過參數(shù)優(yōu)化,對0.43μW信號實現(xiàn)了106放大,信噪比為10dB,實現(xiàn)了微弱光信號的高增益放大,放大后的信號滿足最低信號可分辨條件。散射信號放大特性與光纖內(nèi)部微弱信號放大特性的對比表明,放大率和信噪比均有所下降,說明退偏效應對SBS過程有一定影響,主要降低了放大率和信噪比。
[Abstract]:The detection of weak signal is always difficult in the field of lidar and laser communication. Amplifying the weak light signal is an effective method to improve the operating distance and sensitivity of the system. Among all kinds of optical amplification techniques, optical amplification based on stimulated Brillouin scattering (SBS) effect with optical fiber as gain medium has the advantages of high gain, good frequency selectivity and strong system reliability. It has important application value in the field of optical amplification. In this paper, the influence of Brillouin amplification parameters (including pump power, signal pulse width, fiber length, etc.) on SBS amplification and signal-to-noise ratio (SNR) is studied. The parameters are optimized to amplify weak echo signals with high gain and high signal-to-noise ratio (SNR). Firstly, a mathematical model of Brillouin amplification in optical fiber with noise is established. The numerical model is used to simulate the SBS process in single-mode optical fiber. By changing the parameters of pump power, signal optical power and pulse width, fiber length, the variation of magnification and SNR under different conditions is obtained. The results show that the signal magnification increases with the increase of the pump power, increases with the increase of the signal pulse width, and decreases with the increase of the signal optical power, and the SNR decreases with the increase of the pump light power, and increases with the increase of the signal optical pulse width. It increases with the increase of signal optical power. Firstly, the Brillouin amplification experiment of non-scattering signal is carried out in this paper. The pulse signal is amplified by continuous pump light, and different single-mode optical fibers are used as SBS medium. The parameters of pump light, signal light and fiber are changed to study the effect of the parameters on SBS magnification and signal-to-noise ratio in single-mode optical fiber. The signal to noise ratio (SNR) of 0.43 渭 W signal to noise is 11 dB. The experimental results are in good agreement with the variation of signal to noise ratio (SNR) and magnification power. The experimental method of using fine core optical fiber under weak pump power and ordinary single mode optical fiber with strong pump power is determined. On this basis, Brillouin amplification experiments of scattered signals are carried out, and the effects of pump power, signal pulse width and fiber length, core diameter on magnification and signal-to-noise ratio (SNR) are obtained. Through parameter optimization, the signal to noise ratio (SNR) of 0.43 渭 W signal is 10dB, and the high gain amplification of weak optical signal is realized. The amplified signal satisfies the minimum signal resolution condition. The comparison between the amplification characteristics of scattering signals and that of weak signals in optical fiber shows that both magnification and signal-to-noise ratio (SNR) are decreased, which indicates that the depolarization effect has a certain effect on the SBS process, which mainly reduces the magnification ratio and SNR.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TN253;TN911.7
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本文編號：1822599