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对主振荡功率放大器(MOPA)方式脉冲抽运双包层掺镱脉冲光纤放大器进行了理论研究,分析了放大中抽运脉冲、激光脉冲和拉曼斯托克斯光脉冲的相互作用过程。对增益光纤中上能级粒子数密度随抽运时间的变化进行了分析,求出了最佳抽运脉冲宽度。随着抽运功率的增加,放大过程中出现的受激拉曼效应(SRS)将抑制激光脉冲能量的增加,当采用最佳抽运功率时激光脉冲的能量可达到最大值。分析了光纤长度、纤芯直径对最佳抽运功率、激光脉冲和一级斯托克斯光脉冲的影响。结果表明,当最佳抽运功率时,采用纤芯较粗、长度较短的增益光纤,可以抑制受激拉曼效应,提高激光脉冲的能量与峰值功率。
A theoretical study was made on the pulsed double-clad ytterbium-doped pulsed fiber amplifier by the main oscillator power amplifier (MOPA). The interaction between the pump pulse and the Raman Stokes pulse was analyzed. The variation of the number density of the upper energy level in the gain fiber with the pumping time was analyzed, and the optimal pumping pulse width was obtained. With the increase of pumping power, the stimulated Raman effect (SRS) in the amplification process will restrain the increase of the laser pulse energy, and the laser pulse energy reaches the maximum when the pumping power is the best. The effects of fiber length and core diameter on the optimal pumping power, laser pulse and primary Stokes pulse were analyzed. The results show that when the pump power is the best, a gain fiber with thicker core and shorter length can suppress the stimulated Raman effect and increase the energy and peak power of the laser pulse.