Nd:YAG薄片激光增益介质封装技术

Packaging technique of Nd:YAG thin disk laser gain medium

为了保证Nd:YAG薄片激光器的高功率、高光束质量,需解决薄片增益介质封装后的均匀散热、低波前畸变等关键问题。分析了封装过程中薄片增益介质的热应力,模拟了连接界面无缺陷条件下薄片增益介质的热分布,对封装工艺技术进行改进。优化的封装技术将薄片激光增益介质与微通道冷却器连接在一起,采用超声扫描显微镜、激光干涉仪对薄片激光器的焊接界面与增益介质表面面形进行测试。结果表明:该封装技术实现了直径Φ80 mm的大口径YAG薄片与冷却器焊料层均匀、无空洞的界面连接,同时减小了焊接后薄片的波前畸变,Φ60 mm口径内面形畸变PV值小于1μm,均方根RMS值小于0.15μm。该技术封装的单模块Nd:YAG薄片激光器输出功率达到2.3 k W。

Thermal homogeneity and low wave-front distortion are the main problems affecting the beam quality of high power Nd：YAG thin disk laser which should be solved through packaging technique. The thermal stress of thin disk produced in the process of welding was analysed and the thermal distribution was stimulated, φ80 mm YAG thin disk laser gain medium and micro channel cooler （MCC） were connected by optimized packaging technology. The disk laser was tested by scanning acoustic microscope （SAM） and laser interferometer. The results show that solder layer is homogeneous and void-free, peak- to-valley （PV） departure of optical surface is less than 1 μm and root-mean-square （RMS） is less than 0.15 μm in the circle diameter of 60 mm. On the basis of this packaging technique, high beam quality 2.3 kW output power was extracted with one disk laser.