Magnesium fluoride (MgF2) is a widely used optical window material in lasers. Laser-induced damage in MgF2 materials involves complex thermal-mechanical coupling issues. With the rapid development of high-power fiber laser technologies and application of optoelectronic countermeasures, it is necessary to investigate the damage mechanism of 1.06 μm high-power continuous-wave laser on MgF2 optical windows to clarify the laser damage threshold and factors influencing laser-irradiated MgF2 window mirrors. Therefore, based on the theory of heat conduction and elastic mechanics, a simulation study was conducted using the finite element method. First, based on the thermo-mechanical theory, established a thermo-mechanical damage model for a laser-irradiated MgF2 crystal. Second, we calculated the temperature, stress, and strain fields of single-crystal MgF2 material under the action of a 100 W / cm2 laser. When the laser was irradiated for 4.921 s, thermal stress-induced burst damage was observed, but no melting damage occurred. Finally, the impact of parameters such as the laser power density, spot size, and laser action time on the damage effect was discussed using the parametric scanning method. The calculation results showed that the aforementioned factors significantly impact the damaging effect. Moreover, under the same laser parameters, material burst due to thermal stress is expected to precede the melt damage.

中文翻译：

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高功率光纤激光辐照单晶MgF2热力学损伤行为

氟化镁 (MgF2) 是激光器中广泛使用的光学窗口材料。MgF2 材料中的激光诱导损伤涉及复杂的热机械耦合问题。随着高功率光纤激光器技术和光电对抗应用的快速发展，有必要研究1.06 μm高功率连续波激光器对MgF2光学窗口的损伤机理，明确激光损伤阈值和影响激光损伤的因素。辐照 MgF2 窗镜。为此，基于热传导和弹性力学理论，采用有限元方法进行了仿真研究。首先，基于热机械理论，建立了激光辐照MgF2晶体的热机械损伤模型。其次，我们计算了温度、应力、100 W/cm2 激光作用下单晶 MgF2 材料的应变场和应变场。当激光照射4.921 s时，观察到热应力引起的爆裂损伤，但没有发生熔化损伤。最后，利用参数扫描方法讨论了激光功率密度、光斑尺寸、激光作用时间等参数对损伤效果的影响。计算结果表明，上述因素对破坏效果影响显着。此外，在相同的激光参数下，由于热应力导致的材料破裂预计会先于熔化损坏。采用参数扫描方法讨论了光斑尺寸、激光作用时间对损伤效果的影响。计算结果表明，上述因素对破坏效果影响显着。此外，在相同的激光参数下，由于热应力导致的材料破裂预计会先于熔化损坏。采用参数扫描方法讨论了光斑尺寸、激光作用时间对损伤效果的影响。计算结果表明，上述因素对破坏效果影响显着。此外，在相同的激光参数下，由于热应力导致的材料破裂预计会先于熔化损坏。