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根据非线性薛定谔方程建立了基于可饱和吸收体被动锁模掺Er~(3+)氟化物光纤激光器的理论模型,研究了中红外超短脉冲在掺Er~(3+)氟化物光纤激光器中形成的物理机制,数值模拟了被动锁模掺Er~(3+)氟化物光纤激光器中中红外超短脉冲的演化过程,重点分析了掺Er~(3+)增益光纤长度,可饱和吸收体不饱和损耗对被动锁模掺Er~(3+)氟化物光纤激光器产生中红外超短脉冲的影响,并给出了参数设置范围。研究发现:当小信号增益系数、可饱和吸收体不饱和损耗、腔内净色散量为一定值,掺Er~(3+)氟化物光纤长度在一定范围时,才会出现稳定的锁模脉冲,且随着掺Er~(3+)氟化物光纤长度增加脉冲宽度变窄、光谱变宽、峰值功率增高;当掺Er~(3+)氟化物光纤长度、腔内净色散量、小信号增益系数为一定值时,可饱和吸收体不饱和损耗在一定的范围时可以得到稳定的锁模脉冲,且随着可饱和吸收体不饱和损耗的增加脉冲宽度变窄,光谱先变宽后变窄变化范围不大,峰值功率增加。
Based on the nonlinear Schrödinger equation, a theoretical model of passively mode-locked Er 3+ -fluorescent fiber lasers based on saturable absorber was established. The effects of mid-infrared ultrashort pulses on the Er 3+ -fluorescent fiber lasers (3+) fluoride fiber lasers, the evolution process of the mid-infrared ultrashort pulse in the passively mode-locked Er 3+ -fluorescent fiber laser is numerically simulated. The effects of Er 3+ gain fiber length, saturable absorber The effect of unsaturated loss on the generation of mid-infrared ultrashort pulse by the passively mode-locked Er3 + -fluorescent fiber laser is given and the parameter setting range is given. The results show that when the gain of small signal, the unsaturated absorber of saturable absorber and the net dispersion in the cavity are constant, the stable mode-locked pulse will appear only when the length of Er3 + fluoride fiber is within a certain range , And the pulse width narrows and the spectrum broadens with the increase of Er 3+ fluoride fiber length, the peak power increases. When the Er 3+ fluoride fiber length, the intracavity dispersion, the small signal When the gain coefficient is constant, the stable mode-locked pulse can be obtained when the saturation loss of saturable absorber is within a certain range, and the pulse width becomes narrower as the unsaturated loss of saturable absorber narrows. Narrow changes in the range, the peak power increases.