为了研究斯托克斯光产生的振荡对激光输出功率的限制，采用对双包层光纤激光器的速率传输方程进行近似的解析求解的方法，得到了在斯托克斯光达到阈值时，光纤中激光功率以及激光器抽运功率的解析表达式。通过对解析表达式的分析，结果表明，可以通过缩短光纤长度来提高产生斯托克斯光的阈值和提高抽运光效率的方式使激光功率得到进一步提高。

Double-clad scheme has provided an effective solution to take use of high power semiconductor lasers(or laser arrays)as the pump source. However,with the increase of the fiber laser power,stimulated Raman scattering may reach its threshold and finally limit the further increase of the fiber laser powers. After adopting justified approximation,it was analytically solved. The rate equation of the double-clad fiber lasers without the spontaneous emission terms,and expressions for the fiber laser power and pump power were derived when the Stokes radiation inside fiber reached its threshold. Based on these expressions,dependence of the threshold on the fiber laser parameters were studied.