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理论分析了由掺镱光纤放大器、高非线性光纤(HNLF)和光栅对组成的高功率飞秒脉冲产生系统。由于掺镱光纤放大器固有的有限带宽效应会导致脉冲抛物波形和线性啁啾的畸变,影响脉冲的压缩。在放大器和光栅对之间引入高非线性光纤,可以在展宽脉冲频谱的同时也保持波形和线性啁啾。针对高非线性光纤计算了不同的非线性系数和色散参量对压缩脉冲宽度和压缩效率的影响。研究表明,较高的非线性系数可以进一步降低最小压缩脉冲宽度,但是压缩效率随光纤长度增加而下降的趋势也变得越显著;较低的色散参量有利于得到更短的压缩脉冲,并且相对较高色散参量不会显著地降低压缩效率;在一定范围内,通过延长高非线性光纤可以缩短压缩脉冲,同时需要兼顾压缩效率。
The high-power femtosecond pulse generation system composed of Ytterbium-doped fiber amplifier, high-nonlinear fiber (HNLF) and grating pairs is theoretically analyzed. Due to the inherent limited bandwidth effect of Ytterbium-doped fiber amplifier, the pulse parabolic waveform and the linear chirp distortion will be affected and the pulse compression will be affected. Introducing a highly nonlinear fiber between the amplifier and the grating pair can broaden the pulse spectrum while maintaining waveform and linear chirp. The effects of different nonlinear coefficients and dispersion parameters on the compression pulse width and compression efficiency are calculated for high nonlinear optical fiber. Studies have shown that higher nonlinear coefficients can further reduce the minimum compression pulse width, but the compression efficiency also becomes more pronounced as the fiber length increases; lower dispersion parameters favor shorter compression pulses and relative Higher dispersion parameters do not significantly reduce the compression efficiency; within a certain range, compression pulses can be shortened by extending the length of the highly nonlinear optical fiber, while at the same time requiring both compression efficiency.