1064nm超短激光脉冲的锁模获取与特性分析

Mode-lock acquisition and characteristic analysis of 1064 nm ultrafast laser pulse

为了获得1064 nm皮秒级的超短激光脉冲,探究其波形和功率特征以及泵浦功率和腔长对锁模特性的影响,使用SESAM(半导体可饱和吸收镜)设计相应的W型折叠腔实验系统进行分析,获得了重复频率为92.25 MHz的稳定锁模脉冲。实验结果表明,在腔长不变时,若泵浦功率过低,则锁模不会启动,若泵浦功率过高,则会观察到调Q不稳定及多脉冲现象,且在产生锁模效应的泵浦功率范围内,锁模脉冲的平均功率大小和泵浦功率大小是呈正相关的;在泵浦功率大小一定时,锁模脉冲的波形对折叠腔腔长的变化极为敏感,不足1 mm的腔长变化都会使波形出现较大的抖动,只有在一个极小的范围内才会出现稳定的梳状波。

A folded cavity mode-locked system has been employed by using the core device SESAM(semiconductor saturable absorption mirror)for related experiments.The 1064 nm picosecond ultrafast pulse has been expected to be obtained in experiments.Its characteristics based on waveform and power have been analyzed.At the same time,the influence of pump power and cavity length have also been explored.Finally,the mode-locked pulse waveform with repetition rate of 92.25 MHz has been obtained.It is shown that with a certain cavity length,the mode-locked pulse will not start if the pump power is insufficient.If the pump power is too high,Q-switched instability and multi-pulse phenomena will be observed.Within the range of pump power that leads to mode-locked effect,the average power of the mode-locked pulse is positively corrected with it.When the pump power is constant,the mode-locked pulse waveform is very sensitive to the change of the length of the folded cavity.The change of the cavity length of less than 1mm will make the waveform jitter greatly,and the stable comb wave will appear only in a very small cavity length range.