从实验上研究了掺镱(Yb)双包层光纤放大器中单频脉冲信号放大时,受激布里渊散射(SBS)引起的脉冲畸变现象。实验中采用的单频双包层光纤放大器光纤长度14 m,内包层直径130 μm,纤芯模场直径6.5 μm,在单频脉宽200 ns脉冲放大,且峰值功率3.3 W时观察到后向SBS脉冲,脉宽明显小于输入信号脉宽,分析了受激布里渊散射引起放大脉冲波形畸变的随机特性和功率特性,并采用自由光谱范围30 GHz的法布里-珀罗(F-P)扫描干涉仪验证了SBS频移。

Experimental measurements on the phenomenon of pulse distortion which is induced by the stimulated Brillouin scattering (SBS) in the ytterbium-doped double-clad fiber amplifiers with the single-frequency pulse amplification are presented. In the experiment,the 14 m double-clad single-frequency amplifier with the inner-clad mode diameter 130 μm and the fiber core mode diameter 6.5 μm is adopted. The backward stimulated Brillouin scattering (SBS) pulse is observed when the peak power is up to 3.3 W in the single-frequency pulse amplification with the pulse duration of 200 ns. The pulse width of SBS pulse is apparently narrower than that of the input signal pulse. The stochastic aspect of pulse distortion and power property induced by SBS are analyzed. Meantime the frequency shift of SBS is verified using the F-P interferometer with free spectral range of 30 GHz.