利用二氧化碳激光器加热法，将普通单模光纤拉制成微纳光纤，用湿法转移石墨烯覆盖在微纳光纤上构成复合波导，不同波长的光通过耦合器进入复合波导，以倏逝波的形式与石墨烯相互作用，开展石墨烯优先吸收特性的研究。当短波作为泵浦光时，随着入射强度的增长，测得输出端长波信号光光谱的变化，获得了约3.5 dB的调制深度，0.62 dB·mW-1的调制效率。当长波作为泵浦光并改变入射光强时，在输出端测得作为信号光的短波透过率变化约1.9%。实验结果表明，随着任意波长泵浦光入射光强的增长，复合波导对其表现出优先吸收的特性。实验还测试了长波和短波分别经过复合波导后透过率随输入功率的变化，得出长波的透过率增加速度比短波更快，并从能带和倏逝波两方面作出了对应的理论分析。

In this paper, the normal single-mode fiber is pulled into microfiber by the method of carbon dioxide laser heating, wet method is used to transfer graphene and cover microfiber to form a composite waveguide. The light of different wavelengths enters the composite waveguide through the coupler, interacts with graphene in the form of evanescent waves, thus the research experiment of preferential absorption characteristic is carried out. When a short wave light was used as a pump light, changes in the long wave spectrum with the increase of incident intensity were measured, obtaining a modulation depth of about 35 dB, and a modulation efficiency of 0.62 dB·mW-1. When the long wave light was used as the pump light, the light transmittance of the short wave signal was measured to change by ~1.9%. The experimental results show that with the increase of the incident light intensity of the pump light at any wavelength, the composite waveguide exhibits its preferential absorption characteristics. In addition, when the long-wave and short-wave waves passed through the composite waveguide, the transmittance changes with the input power were tested, experiments show that the long-wavelength transmittance increases faster than the short-wavelength transmittance, and the corresponding theoretical analysis can be made from the two aspects of energy band and evanescent wave.