提出一种新型的基于复合微球腔WGM(回音壁模式)共振谱的全光纤激光腔内选模方法。通过多层介质和并联结构构造复合光学微球腔, 基于FDTD(有限差分时域)算法仿真并分析了复合微球腔内WGM的光场分布特性。基于复合光学微球腔-拉锥光纤的最佳耦合条件, 计算得到其传输透射谱。通过优化复合微球腔的参数并改进耦合条件, 实现了WGM共振谱带宽的压缩和边模抑制比的提高。所获得的窄带透射谱对实现全光纤激光选模具有重要意义。

We propose a novel mode-selection method in all-fiber laser cavity based on composite optical microsphere cavity Whispering-Gallery-Mode (WGM) resonance spectra and simulate and analyze the optical field distribution of the microsphere cavities constructed with multilayer media and parallel structures by using the Finite Difference Time Domain (FDTD) algorithm. On the basis of the optimal conditions for coupling the microsphere cavities with tapered fibers, we calculate and obtain their transmission spectra. By optimizing the parameters of microsphere cavities and improve the coupling conditions, we compress the WGM resonance spectra bandwidth and enhance the side-mode suppression ratio. The acquired narrow-band transmission spectra are of major significance to all-fiber laser mode selection.