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提出了一种主振荡光纤放大系统,围绕提高脉冲信号的峰值功率和拓宽系统重复频率的调制范围两方面进行了实验研究。实验采用电脉冲调制和声光调制的方式对光脉冲序列进行调制,抑制了半导体种子源在小信号放大时产生的放大自发辐射效应和自激振荡,解除了种子源对系统重复频率的限制,使系统的重复频率在1~200kHz范围内连续可调。在声光调制器对光脉冲的调制过程中,声光Q开关有效抑制了放大过程中由自相位调制引起的光谱展宽。实验采用大模场棒状光子晶体光纤作为增益介质,提高了光脉冲的峰值功率和输出光的光束质量,抑制了因峰值功率过高引起的非线性效应,最终实现了脉冲宽度为1.12ns、峰值功率为2.01 MW的稳定光脉冲输出,平均功率超过56 W,输出光束质量接近衍射极限(M_x~2=1.49,M_y~2=1.54)。
A main oscillation optical fiber amplification system is proposed. The experimental research is focused on two aspects: increasing the peak power of the pulse signal and broadening the modulation range of the system repetition frequency. Experiments using electrical pulse modulation and acoustooptic modulation on the optical pulse sequence modulation, inhibit the semiconductor seed source in the small signal amplification amplified spontaneous emission effect and self-oscillation, the lifting of the seed source on the system of repetition rate restrictions, The system’s repetition rate in the range of 1 ~ 200kHz continuously adjustable. During the modulation of the light pulse by the acousto-optic modulator, the acousto-optic Q-switch effectively suppresses the spectral broadening caused by self-phase modulation during amplification. In the experiment, large-mode field photonic crystal fiber rod as the gain medium, the peak power of light pulse and the beam quality of the output light are increased, the non-linear effect due to the peak power is suppressed, and finally the pulse width is 1.12ns, the peak The power is 2.01 MW with a stable optical pulse output. The average power exceeds 56 W and the output beam quality approaches the diffraction limit (M_x ~ 2 = 1.49, M_y ~ 2 = 1.54).