光纤中基于SBS效应的微弱光信号放大技术研究

发布时间：2018-04-30 02:11

  本文选题：受激布里渊散射 + 微弱信号放大　； 参考：《哈尔滨工业大学》2016年硕士论文

【摘要】：微弱信号的探测一直是激光雷达和激光通信等领域的难点。对微弱光信号进行放大,是提高系统作用距离和灵敏度的有效手段。在各种光放大技术中,以光纤为增益介质的基于受激布里渊散射(SBS)效应的光放大技术具备增益高、频率选择性好、系统可靠性强的优点,在光放大领域有重要的应用价值。本文研究光纤布里渊放大参数(包括抽运光功率、信号光脉宽、光纤长度等)对SBS放大率和信噪比的影响规律,优化参数,以实现高增益、高信噪比的微弱回波信号放大。首先建立了含噪声、用于数值研究的光纤中布里渊放大特性数学模型。利用此数值模型对单模光纤中的SBS过程进行数值模拟,通过单独改变抽运光功率、信号光功率及脉宽、光纤长度等参数,得出不同条件下放大率和信噪比的变化情况。研究表明:信号放大率随抽运光功率增加而提高,随信号光脉宽增加而提高,随信号光功率增加而下降;信噪比随抽运光功率增加而下降,随信号光脉宽增加而提高,随信号光功率增加而提高。实验上,本文首先开展了非散射信号的布里渊放大实验研究。采用连续抽运光放大脉冲信号光,以不同单模光纤作为SBS介质,改变实验中抽运光、信号光、光纤参数,研究其对单模光纤中SBS放大率和信噪比的影响。实验对0.43μW信号光实现了107放大,信噪比为11dB。实验研究与理论研究的放大率和信噪比的变化规律基本相符,确定了在弱抽运光功率情况下使用细芯径光纤,强抽运光功率下使用普通单模光纤的实验方法。在此基础上,开展了散射信号的布里渊放大实验研究,获得了抽运光功率、信号光脉宽和光纤长度、芯径对放大率和信噪比的影响规律。通过参数优化,对0.43μW信号实现了106放大,信噪比为10dB,实现了微弱光信号的高增益放大,放大后的信号满足最低信号可分辨条件。散射信号放大特性与光纤内部微弱信号放大特性的对比表明,放大率和信噪比均有所下降,说明退偏效应对SBS过程有一定影响,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.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN253;TN911.7
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本文编号：1822599