研究了百皮秒脉冲在掺镱双包层光纤放大器(YDDCFA)中的放大特性及非线性效应。在1053 nm波段,分别对重复频率为70 MHz的准连续百皮秒信号和1 Hz的单脉冲百皮秒信号进行了放大。准连续脉冲输入信号平均功率为55 mW,谱宽为0.016 nm,饱和增益为7.02 dB,使用法布里-珀罗(F-P)干涉仪测量自相位调制(SPM)效应引起的信号光谱展宽为0.01 nm。单脉冲输入信号峰值功率为8.1 W,在输出峰值功率为6950 W、增益为29.3 dB时发生受激拉曼散射(SRS)效应,利用光纤布拉格光栅拉伸扫描的方法,观察到SPM和SRS效应引起的光谱变化,利用单模光纤的色散作用分离信号脉冲和斯托克斯脉冲,对SRS现象进行了判断,解决了单脉冲光谱不易观察的问题。实验结果表明,SRS效应是制约百皮秒脉冲放大的主要因素。

The amplification and nonlinear effects of 100 ps pulse in the diode-pumped Yb-doped double-clad fiber amplifier (YDDCFA) is investigated. The YDDCFA is seeded with 100 ps pulses with a spectrum centered at 1053 nm at repetition rate of 70 MHz and 1 Hz,respectively. The saturated gain of the quasi-continuous pulse input signal with average power of 55 mW,spectral width of 0.016 nm,is 7.02 dB. And the spectrum broadening caused by SPM is 0.01 nm,measured with F-P interferometer. The SRS is observed when the peak power of the single-shot pulse is amplified to 6950 W corresponding to a gain of 29.3 dB. Novel methods are devised to detect the spectrum of single shot. The change of spectrum caused by SPM and SRS is measured using a stretched fiber Bragg grating;and the Stocks pulse and signal pulse are separated using the dispersion of long sing mode fiber,revealing the SRS effect. Experimental results show that the SRS is the main limit of amplification of 100 ps pulse.