偏斜光线抽运下回音壁模式光纤激光辐射的偏振特性

Polarization Properties of a Whispering-Gallery-Mode Fiber Laser Pumped by the Evanescent Wave of Skew Beam

研究了消逝波激励的回音壁模式(WGM)光纤激光器的偏振特性。实验发现,在抽运光以偏斜光线方式沿光纤的近轴向抽运时,回音壁模式激光既存在横电(TE)波又存在横磁(TM)波;对径向模式数(l)和角模式数(n)相同的回音壁模式,TE波和TM波之间的波数差随增益包层溶液折射率的增加而单调地减小。根据消逝波激励的WGM光纤激光的激励机制,结合圆柱型微腔中确定WGM共振位置的解析渐近公式,合理地解释了观察到的实验结果。

The polarization properties of a whispering-gallery-mode（WGM） fiber laser pumped by the evanescent wave of skew beam are studied.It is found from the experiments that when pump beam transmits in a bared optical fiber in skew way,both transverse electric（TE） wave and transverse magnetic（TM） wave exist in the laser emission,and the wave-number difference between TE and TM waves decreases monotonely with the increase of the refractive index of cladding solution.Based on the excitation mechanics of evanescent-wave pumped WGM fiber laser and the analytic asymptotic formula to determine the resonant positions of a WGM,the observed experimental results are well explained.