为了使掺铒光纤超荧光光源C波段与L波段光谱匹配良好，实现高平坦度的C+L波段宽带光源，提出了一种三级双泵浦光源结构。首先，使用三段不同型号、不同长度的掺铒光纤，两个980 nm激光二极管，波分复用器，隔离器以及3 dB耦合器构成的光纤环形镜搭建宽带光源实验装置；然后，通过不断优化三段掺铒光纤的长度，调节两级抽运源功率获得高平坦度C+L波段光源输出;最后对其产生机理进行分析。实验结果表明，当三段掺铒光纤的长度分别为11.5 m、53 m和6.5 m，两级抽运源功率分别为65 mW和115 mW时，输出光谱的3 dB带宽为75.68 nm，在1 543~1 603 nm波段光谱的平坦度<±1.3 dB(不加任何滤波器的条件下)。获得的高平坦度C+L波段宽带光源可以更好地满足光纤传感、光纤通信系统等领域的应用要求。

In order to realize a high flattening C+L-band fiber source by C band matching L band closely, a superfluorescent light source structure with three-stage two-pumping is presented.Firstly, the experimental equipment is composed of three erbium-doped fibers, two 980 nm LDs,a Wavelength Division Multiplexer (WDM),an isolater(ISO)and a 3 dB coupler.Then, a high flattening C+L-band fiber source is achieved by optimizing the lengths of three erbium-doped fibers and adjusting the powers of two pumps, and the mechanism of production is also analyzed.Experimental results indicate that when the lengths of three fibers are 11.5 m, 53 m, 6.5 m and the powers of the two pumps are 65 mW, 115 mW respectively, the light source can offer a linewidth in 75.68 nm with a power ripple of 3 dB, and the flatness of the spectra from 1 543 nm to 1 603 nm is less than ±1.3 dB without any external spectral filters.The high flattening C+L-band superfluorescent light source can satisfy the requirements of the optical fiber sensing and optical fiber communication systems.