千瓦级传导冷却半导体激光器阵列热特性

Thermal characteristics of kW-level conduction-cooled semiconductor laser array

随着半导体激光器输出功率的进一步提高,热管理已经成为制约其性能和可靠性的关键瓶颈之一。利用有限元方法对千瓦级高功率传导冷却型(G-Stack)半导体激光器阵列的热特性进行数值模拟与分析。结果表明工作脉宽大于250μs时器件各发光单元之间会发生严重的热串扰现象。在横向及垂直方向的热量分别为64.7%与35.3%,横向方向热阻的74.9%及垂直方向热阻的66.5%来自CuW,表明CuW对于激光器的散热性能有着决定性的影响。实验测试了器件在不同占空比条件下的光谱特性,得到工作频率分别为20、30、40 Hz相对50 Hz的温差分别为2.33、1.56、0.78℃,根据累积平均温度法计算得到的温差分别为2.13,1.47,0.75℃,理论模拟结果相对于实验结果的平均误差小于6.85%,结果表明理论模拟结果和实验瞬态热阻基本吻合。

With the increase in output power of high power semiconductor lasers （HPSLs）, thermal management is one of the critical bottlenecks affecting the optical-electrical performance and reliability of HPSLs. Thermal characteristics of a kW-level conduction cooled semiconductor laser array were analyzed based on numerical simulations and experiments. Firstly, transient thermal behavior was studied using finite element method （FEM）. There is significant ＂thermal crosstalk＂ behavior among the semiconductor laser bars with pulse width greater than 250 pus. It shows thermal resistances along horizontal and vertical directions are 64.7% and 35.3%, respectively, indicating that heat mainly dissipates along horizontal direction. 74.9% of thermal resistance along horizontal direction and 66.5% of thermal resistance along vertical direction origin from CuW layer, which shows that CuW is the most significant factor affecting the efficiency of thermal dissipation. Based on accumulated average temperature method, the simulated temperature differences are 2.13, 1.47, 0.75 ℃ at the repetition frequencies of 20, 30 and 40 Hz compared with that at the frequency of 50 Hz. Average junction temperature rises at different repetition frequency have been measured using spectral method, and the temperature differences at the repetition frequencies of 20, 30 and 40 Hz are 2.33, 1.56, 0.78 ℃, respectively. The average error is less than 6.85% between experiment results and numerical simulation. It shows that the simulated transient thermal resistance is coincident with the experimental result.