搭建了一台用于研究石英单模光纤中非线性光谱特性的实验系统。利用磷酸钛氧钾（KTP）晶体倍频电光调Q脉冲Nd3+∶YAG固体激光器，将输出脉宽为10 ns，最大峰值功率达到50 MW，波长为 531.81 nm±0.26 nm的激光作为抽运光源，抽运长度分别为250 m和500 m的石英单模光纤。根据马吕斯定律使用偏振片调节抽运光的输出能量。在实验系统稳定工作的条件下，调节抽运光输出能量分别为220.6 kW和170 kW时，获得了可见光范围内250 m和500 m石英单模光纤的多级非线性光谱。基于石英单模光纤中的三阶非线性理论，分析了实验中所获得非线性光谱的特性。理论分析和实验数据均表明：石英单模光纤长度越长，非线性光谱强度、耦合增益系数越大，能量阈值越低，而石英单模光纤长度越短，非线性谱线的展宽和散射附加峰的产生越容易。

An experiment system is set up for studying the characteristics of nonlinear spectrum in quartz single mode fiber. The electro-optical Q-switched pulsed Nd3+∶YAG solid laser, frequency-doubling by potassium titanium oxide phosphate (KTP) crystal, with output pulse width of 10 ns, the maximum peak power of 50 MW, and wavelength of 531.81 nm±0.26 nm, is used to pump the quartz single mode fibers with lengths of 250 m and 500 m. Based on the principle of Malus law, a polarizing plate is used to adjust the output power of the pumping source. Under the stable operation condition, multi stage nonlinear spectra of 250 m and 500 m quartz single mode fibers in the visible region are obtained, while the output powers of pumping sources are 220.6 kW and 170 kW. Based on the principle of the third-order nonlinear effects in quartz single mode fiber, the characteristics of the nonlinear spectra obtained in the experiment are analyzed. Both the theoretical analysis and experimental results indicate that the longer the length of quartz single mode fiber, the larger the relative intensity of nonlinear spectrum and the coupling gain coefficient, and the smaller the energy threshold; while the shorter the length of quartz single mode fiber, the easier the broadening of nonlinear spectra and the generation of scattering additional peak.