Modal instability in high power solid-state lasers with an unstable cavity

作者：Su, Hua^*; Wei, Yu-Xin; Wang, Xiao-Jun; Tang, Chun

来源：Optics Communications, 2015, 341: 37-46.

DOI：10.1016/j.optcom.2014.12.009

• Laser resonators
• Laser stabilization
• Thermal effects
• Solid-state laser

A phenomenon of modal instability is investigated theoretically in some high power solid-state lasers with an unstable cavity. This modal instability is caused by a thermo-optic-thermo feedback coupled with an asymmetrical laser oscillation inside some unstable cavities. Numerical investigations indicate that this instability can appear in all lasers with Nd3+-doped disk scheme, Yb3+-doped disk scheme and direct-liquid-cooled slab scheme, but the physical mechanisms of optic-thermo feedback in the three schemes are completely different. It is shown that the modal instability can appear within a special power range only in the Nd- or Yb-doped disk lasers due to certain saturation phenomenon, but exhibits a power threshold in the direct-liquid-cooled slab lasers. Therefore different strategies to mitigate the modal instability in different lasers are suggested. Finally, the presence of transverse modal instability in the Nd:YAG thin-disk laser is confirmed qualitatively by an experiment.

• 出版日期2015-4-15
• 单位中国工程物理研究院; 北京应用物理与计算数学研究所