Q-switching instability restricts pulse shortening in Kerr-lens mode-locked lasers (KLMLs). However, Q-switching suppression in KLMLs has not been discussed to date because of the difficulty of treating the Kerr-lens effect theoretically. We investigated parameter ranges for stable Kerr-lens mode-locking (KLM) against Q-switching theoretically and experimentally. We found the parameters and ranges required to suppress Q-switching in hard- and soft-aperture KLMLs. In soft-aperture KLMLs, both intracavity power and spatial mode matching between a pump beam and a cavity mode were found to be critical. These findings were verified experimentally using an Yb:${\rm Y_2O_3}$ KLML. Our results provide cavity design criteria for stable KLMLs against Q-switching.

中文翻译：

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Kerr-lens锁模的Q开关稳定性极限

Q开关的不稳定性限制了Kerr透镜锁模激光器（KLML）中的脉冲缩短。然而，由于理论上难以处理克尔-伦斯效应，因此迄今为止尚未讨论KLML中的Q开关抑制。我们在理论和实验上研究了稳定的Kerr-lens锁模（KLM）对抗Q开关的参数范围。我们发现抑制硬孔和软孔KLML中的Q切换所需的参数和范围。在软孔KLML中，发现腔内功率以及泵浦光束和腔模之间的空间模匹配都是至关重要的。这些发现已使用Yb：$ {\ rm Y_2O_3} $ KLML进行了实验验证。我们的结果为稳定的KLML抗Q开关提供了腔设计标准。