影响柱形微腔回音廊模激光抽运阈值能量的因素

将石英光纤浸入染料溶液中形成圆柱形微腔,并采用近轴向消逝场抽运的方式,激发染料溶液的激光增益。柱形微腔回音廊模(WGM)激光抽运阈值能量的高低与抽运激光的消逝场和回音廊模消逝场的空间重叠程度有直接关系,同时也需要考虑低阶与高阶回音廊模损耗的影响。通过改变染料溶液的折射率以及光纤直径,来改变回音廊模的消逝场分布,从而改变两种消逝场空间重叠的体积以及回音廊模的损耗。实验结果表明,柱腔直径不变时,存在一个最佳的溶液折射率值;同时,溶液折射率不变时,也存在一个最佳的柱腔直径,使得一阶回音廊模激光抽运阈值能量最低。

Factor of Influencing Pumping Threshold Energy of Whispering-Gallery-Mode Laser in a Cylindrical Micro-Cavity

A cylindrical microcavity was made by immersing a silica optical fiber in a dye solution.The pumping threshold energy of the whispering-gallery-mode (WGM) laser strongly related to the spatial overlapping between the evanescent field of the pumping laser and the WGMs,and it also was influenced by the losses of the WGMs of low and high order.The distribution of evanescent field of the WGM can be changed through changing the refractive index of dye solution and the diameter of fiber.Then the spatial overlapping and the losses of WGM are changed. The results show that there is a lowest pumping threshold value of the first order WGM laser when one of the refractive index of the solution and the diameter of fiber is changed but the other is invariable.