Fiber core mode leakage induced by refractive index variation in high-power fiber laser
Yan Ping, Wang Xuejiao, Huang Yusheng, Fu Chen, Sun Junyi, Xiao Qirong, Li Dan †, Gong Mali
       

(color online) (a) Mode coupling coefficient of LP01 core mode to the first-order cladding modes; (b) mode coupling coefficient of LP11 core mode to the second-order cladding modes.