光纤受激布里渊效应是一种非常重要的光纤非线性效应, 受激布里渊增益谱的线型特性, 对于光谱分析、 微波光子学、 光纤传感等领域的应用, 至关重要。 针对增益谱线型特性研究, 现有方法难以获取高信噪比的增益谱数据, 介绍了一种采用两个窄线宽激光器的增益谱测量方法, 其中一个激光器作为探针信号, 另一个可调谐激光器作为泵浦信号在宽波段范围内进行推扫。 得益于激光器的高信噪比单谱线特性, 并利用偏振跟随特性, 实现了高信噪比的受激布里渊增益谱测量。 测量并分析了不同泵浦功率, 对于谱型和线宽等受激布里渊增益特性的影响, 特别是, 直接实验测量了增益谱型从洛伦兹线型到高斯线型的演化, 揭示了泵浦功率等影响受激布里渊增益水平的因素, 对于增益谱线型的影响。 实验发现, 当泵浦功率超过15 dBm时, 增益谱出现饱和效应, 导致测量增益谱线宽开始随泵浦功率提高而展宽, 难以直接测量得到高泵浦功率时的高斯线型的增益谱。 提出通过归一化等校正处理, 以获取受激布里渊增益谱与待测信号光谱的有效卷积信息, 从而得到了近似为高斯线型的增益谱型； 针对中间增益区域增益谱型较为复杂, 缺少合适增益谱线型演化数学模型的难题, 给出了一种基于k次洛伦兹函数拟合的谱型模型, 描述从洛伦兹线型到高斯线型的完整演进过程。 实验表明拟合效果良好, 是一种行之有效的受激布里渊增益谱线型数学模型, 可完整描述增益谱在不同增益时的线型。 最后, 探索了受激布里渊效应在光谱分析方面的应用, 通过合理选择泵浦功率等手段, 增益谱型为高斯线型时的光谱分光效果最佳, 获取了0.2 pm分辨率的6314CA稳定光源的光谱, 显示了光纤受激布里渊效应在超高分辨率光谱分析领域的巨大技术优势, 而这对于新一代光网络的验证评估至关重要。

Stimulated Brillouin Scattering(SBS) is an important nonlinear effect which is observed in optical fiber, the properties of SBS gain spectrum lineshape play a key role, for use in some applications such as spectrum analysis, microwave photonic filtering and optical fiber sensors based on Brillouin amplification. High signal to noise ratio (SNR) measurement data is impossible with current methods, limits analyzing the lineshape of SBS gain spectrum. A method for brillouin gain spectrum measurements in standard single-mode fiber by two narrow-linewidth laser is presented, using one as the probe signal to measure, and the other as the pump signal, sweeping a wide spectral span of around the probe signal. Benefit from narrow-linewidth laser and polarization pulling of SBS, high SNR measurement of brillouin gain spectrum is achieved. The brillouin gain spectrum is measured for different power levels of pump signal, the relation of power levels and relevant SBS parameters such as linewidth and gain profile is studied, particularly, the evolution of the SBS gain profile from Lorentzian to Gaussian as predicted by current theory is also experimental verification and analysis, show the SBS spectrum lineshape affected by the gain level involving different optical power levels of the stimulating signal. Experimental results show that with pump power up from 15dBm, the saturation is preset, so if directly measured the FWHM of SBS gain spectrum, its broadens as the pump power increases. This gaussian functional form of SBS gain spectrum could not be directly measured experimentally at high pump powers, linearizing the response is proposed, in order to get valid information of the convolution between the SBS spectrum and the measured signal spectrum, so the lineshape is confirmed to be gaussian. In the intermediate gain region, the SBS spectral shape does not fit well with current functions, lack of proper lineshape evolution model, so a mathematical model with Lorentzian function to the power of a variable value k was proposed, to resolve the difficult fitting problems of lineshape evolution from Lorentzian to Gaussian. Experimental results with excellent accuracy, proven an effective mathematical model of SBS gain spectrum lineshape, to describe the profile of SBS spectrum with different gain level. The use of SBS response for spectral analysis is proposed. Accordingly, the quality of the SBS based spectrum analysis is highly dependent on the optical power of the pumping signal, the SBS gain as filtering with Gaussian profile is used. The optical spectrum of 6314CA stabilized optical source with 0.2 pm resolution is obtained, show a great potential candidate for ultra-high resolution spectral analysis, will be a useful diagnostic tool for new generation optical network research and development (R&D).