利用充人激光染料的石英毛细管构成了一个双层结构的圆柱形微腔,在S和P偏振光抽运条件下,分别观察到了微腔中的横磁波或横电波回音壁模式激光辐射。实验结果表明,横磁波激光光谱出现了明显的干涉调制现象,调制周期随染料溶液折射率的增加而增大,随毛细管内外半径比的增加而减小;横电波激光光谱则没有出现干涉调制现象。用双层微腔结构中反射波对折射波的干涉调制效应,成功解释了观察到的实验现象。双层结构圆柱形微腔中回音壁模式激光的干涉调制现象,为多模回音壁模式激光的模式选择提供了一定的参考。
A double-layered cylindrical microcavity is fabricated by filling Rh6G dye solution into a fused capillary. By pumping with s- and p- polarized laser light respectively, whispering-gallery mode lasing emission with transverse magnetic and transverse electric polarization is observed. The interference modulation effect in the whispering- gallery-mode lasing spectra is found when pumped by s- polarized light. And the modulation period increases with the refractive index of dye solution, but decreases with the ratio of the external to internal diameter of a capillary. By applying the interference modulation theory on the reflective and refractive waves in the double-layered cylindrical microcavity, the observed phenomenon can be explained successfully. The interference modulation effect provides a certain reference for mode selection in a multimode whispering-gallery-mode laser.