高功率薄片激光介质温度与应力数值模拟

Numerical simulation of medium temperature and stress for high power disk laser

Nd:YAG薄片激光介质采用上表面二极管阵列泵浦,下表面冷却的工作方式,对Nd:YAG薄片激光介质和Cu冷却器建立了理论计算模型。分别计算了在不同泵浦面积的条件下薄片的温度分布和应力大小,薄片泵浦面积大小与应力的关系,以及在Nd:YAG薄片与Cu冷却器之间增加与Nd:YAG热膨胀系数相近的介质层材料对应力影响的关系。计算结果表明:在泵浦功率密度、外界温度和冷却条件一致的情况下,泵浦光泵浦整个薄片时总体应力最小,应力主要是由于Nd:YAG薄片与Cu冷却器热膨胀系数不匹配而产生的,增加介质层能改变应力大小;泵浦光泵浦部分薄片时总体应力较大,应力主要是薄片泵浦区与非泵浦区温差造成的,与介质层无关。

This paper presents the numerical simulation of the Nd.. YAG disk as the high power laser medium. The upper surface of the disk is pumped by the diode array, and the other side is cooled by copper heat sink. Temperature and stress are simulated for the disk partly pumped by an anea of 7.5 mm×6. 2 mm as well as pumped from its whole surface. The results show that with the same pumping power intensity,environment temperature and cooling,the overall stress of the disk fully pumped is smaller than that of the partly pumped disk. As the former is mainly coused by the difference of themal expansionbetween the disk andthe copper heatsink,it reduces when the compound diamond is used as a medium. While the latter,which is mainly coused by the temperature difference between the pumped and non-pumped area,changes little with the compound diamond medium.