光源相干长度对光纤Fabry—Perot干涉的影响

从数值上分析了光源相干长度对光纤Fabry-Perot干涉的影响。推导了光源在理想情况和非理想情况下的光纤Fabry—Perot干涉模型，通过计算机模拟了干涉信号，指出在非单色光源下，干涉条纹失去周期性，随着腔长相干长度比增加干涉条纹的变化幅度减小，最后演化成一条直线，条纹的可见度也慢慢趋近于零。综合考虑了光纤的耦合效率和光源的非单色性对干涉信号的影响，随着腔长的增加，干涉信号的幅值和变化幅度都在减小，信噪比变差。要得到好的干涉信号，腔长不宜选择过大，必须使光源的腔长相干长度比值低于0．1。

Influence of Optical Coherence on Fiber-Optic Fabry-Perot Interferometer

The influence of optical coherence on fiber-optic Fabry-Perot interferometer was analyzed. The model of fiber-optic Fabry-Perot interferometer was established when ideal or unideal optical source was applied. Through simulating interferometric signal by computer under the condition of nonmonochromatic light, the symmetry of fringes deteriorated, the fluctu- ating domain of fringes became small as the ratio of cavity length to coherence length increasing. At last the fringes changed into a line. The visibility of fringes approached zero slowly. At the same time, the influence of coupling efficiency and nonmonochromatic optical sources was studied. When the cavity length rose, both the amplitude and varing range of interferometric signal decreased, signal-to-noise ratio deterioated. In order to obtain good quality interferometric signal, the cavity length should be suitable and the ratio of cavity length to coherence length must be less than 0. 1.