An immersed liquid cooling slab laser is demonstrated with deionized water as the coolant and a Nd:YAG slab as the gain medium. Using waveguides, a highly uniform pump beam distribution is achieved, and the flow velocity distribution is also optimized in the channels of the gain module (GM). At various flow velocities, the convective heat transfer coefficient (CHTC) is obtained. Experimentally, a maximum output power of 434 W is obtained with an optical–optical efficiency of 27.1% and a slope efficiency of 36.6%. To the best of our knowledge, it is the highest output power of an immersed liquid cooling laser oscillator with a single Nd:YAG slab.

低温应用的大功率器件需要设计高冷却效率的液冷室结构。采用计算流体动力学（CFD）方法模拟了以液氮-氮气两相流为制冷剂的空腔结构、微通道结构和扰流柱结构的流动与传热过程。结果表明，相比于空腔结构和微槽道结构，扰流柱结构具有较好的换热能力。圆形扰流柱易发展45°方向支流，而方形扰流柱结构有利于垂直方向流速均匀化。相较于平行排布，扰流柱交错排列时圆形和方形扰流柱结构中流速分布更为均匀。对比对流换热系数发现，交错排布优于平行排布，方形扰流柱优于圆形扰流柱。换热效果最好的结构为交错排布的2 mm方形扰流柱，对流换热系数为4223 W/(m²·K)，较空腔结构提高125.83%。采用上述结构进行测试验证，在107.6 W加热功率工况下冷头测温点温度与相同功率下仿真结果有较好的对应性。