跳模会导致单波长光纤环形激光器相干性有不同程度的退化,严重影响光学系统的性能。设计一种基于匹配干涉仪的相干坍塌抑制方案,分析抑制机理。并分别搭建臂差可调的空间光匹配干涉仪(SLMI)和全光纤结构匹配干涉仪(AFMI),通过实验对抑制效果进行方案验证。结果表明:当SLMI的等效臂差不断逼近理论值时,可监测到多模匹配干涉现象,该现象等效于单纵模激光干涉,从而实现相干坍塌抑制;AFMI结构紧凑,便于嵌入光纤相干探测系统中,能有效抑制随机跳模引入的相干坍塌和相位噪声谱级的大幅上升,降低系统虚警概率。作为一种被动手段,匹配干涉仪对抑制或规避模式失稳引起的相干坍塌具有指导意义。

Mode hopping causes varying degrees of degradation in the coherence of single-wavelength fiber ring lasers, which seriously affects the performance of optical systems. In this work, a method for coherence collapse suppression based on a matched interferometer is designed, and the suppression mechanism is analyzed. A space-light matched interferometer (SLMI) with adjustable arm difference and an all-fiber matched interferometer (AFMI) are constructed separately, and the suppression effect is verified experimentally. Experimental results show that when the equivalent arm difference of the SLMI continuously approaches the theoretical value, multi-mode-matching interference can be monitored. This is equivalent to single-longitudinal-mode laser interference, thereby successfully suppressing coherence collapse. The AFMI is compact and easy to incorporate into a fiber coherence detection system. It is found that the AFMI can effectively suppress the coherent collapse and the sharp increase of phase noise spectrum level introduced by random mode hopping; this helps to reduce the false alarm probability of the system. As a passive method, matched interferometers play a significant role in suppressing or evading coherence collapse caused by mode instability.