【摘要】 为提高高功率大面阵垂直腔面发射激光器(Vertical Cavity Surface-Emitting Laser,VCSEL)封装散热性能，提升激光功率和电光转换效率等特性，探索VCSEL芯片低热阻封装形式，提出硅基歧管式微通道热沉直接贴装VCSEL的新型封装散热方案，研制多款液冷VCSEL激光模块，采用电学法对各模块热阻特性研究，分析各模块激光功率和电光转换效率(Power Conversion Efficiency, PCE)。应用激光光谱法监测光谱漂移，反演计算30 A下各模块热阻和芯片结温。表明热阻显著影响结温，结温制约激光功率。得出新方案VCSEL模块在8 A电流、20℃液冷条件下的总热阻由传统模块0.39 K/W降至0.23 K/W，降幅41%，最大激光功率由80 W增至120 W以上，增幅超50%。表明该方案有效增强了VCSEL模块的散热能力和光电性能。对大面积高热流密度芯片热管理有重要参考价值。更多还原

【Abstract】 Objective High-power vertical cavity surface-emitting lasers(VCSELs) offer numerous advantages over traditional edge-emitting semiconductor lasers, including ease of two-dimensional expansion and integration, low temperature drift coefficient, and excellent beam quality. To enhance the laser power of VCSELs, they are often expanded into VCSEL arrays. VCSEL arrays have rapidly developed in many applications such as laser illumination, laser pumping, and laser heating, finding widespread applications in military, industrial, medical,and many other fields. However, due to the special short resonant cavity of VCSELs and their distributed bragg reflector(DBR) structures on both sides, they not only suffer from severe self-heating issues but also face difficulties in heat dissipation. Additionally, due to the compact arrangement of high-density light-emitting point arrays, the heat accumulation problem in VCSEL arrays is particularly severe, with heat flux densities exceeding k W/cm2. It severely limits the laser power output and electro-optic conversion efficiency of VCSEL arrays,especially for large-area VCSEL arrays with dimensions of several millimetres or more, which possesses tens of thousands of densely packed light-emitting point arrays. Therefore, there is an urgent need for low-thermal resistance packaging and efficient heat dissipation to address this challenge. For this purpose, a low thermal resistance packaging scheme has been proposed, and quantitative characterisation and comparative analysis have been conducted.Methods Four types of liquid-cooled high-power large-area VCSEL array laser modules are designed and fabricated consisting of different structures and materials(Tab.1,Fig.3,Fig.4), The thermal resistances of these modules are tested with electrical transient measurement method under loading current of 8 A, which is nondestructive testing method. In addition, the compositions of the thermal resistances are tested and analysed with the structural function method(Fig.2,Fig.5). Under loading current of 30 A, the wavelength variation and laser power of four types of high-power VCSEL array laser modules are tested with laser spectroscopy testing system.Results and Discussions The test results show that the laser power of the high-power, large-area VCSEL array laser module, directly mounted on the silicon-based manifold microfluidic heat sink in module 3 and 4, both exceed 120 W, which is more than 50% higher than that of the traditional liquid-cooled multi-layer VCSEL laser module in module 1(Fig.8(a)). The highest electro-optical conversion efficiencies of the four types of laser modules are approximately 40%, indicating that the chip itself primarily determines the highest electro-optical conversion efficiency of the laser module, and the external packaging’s heat dissipation level cannot significantly play a role. However, it can enhance the electro-optical conversion efficiency of the high-power output stage in the laser module. Under a loading current of 30 A, the electro-optical conversion efficiencies of the four types of laser modules are 25.37%, 32.43%, 34.55%, and 35.90%, respectively(Fig.8(b)). Meanwhile, the junction temperatures rise of the chips is 93.20 ℃, 71.96 ℃, 46.25 ℃, and 46.07 ℃, respectively(Tab.2). Structural function analysis reveals that the thermal resistance of traditional multi-layer laser module 1 comprises up to 5items, resulting in a cumulative total thermal resistance of up to 0.39 K/W(Fig.9). The thermal resistances of the four types of laser modules are 0.39 K/W, 0.29 K/W, 0.24 K/W, and 0.23 K/W, respectively(Fig.12). The thermal resistance of the module 4 has been reduced by 41% compared to the traditional module 1. The module 3 has achieved a heat dissipation effect comparable to that of module 4 and even has surpassed it at high power and high heat flux stages. However, the price of single-crystal diamond is too high.Conclusions By reducing the packaging thermal resistance link of high-power, large-area VCSEL array laser module and adopting a new form of direct packaging with a silicon-based manifold microfluidic heat sink, the thermal resistance of the module is effectively reduced. Compared with the traditional multi-layer packaging form, the thermal resistance of the module is reduced from 0.39 K/W to 0.23 K/W, a 41% decrease. Under the new packaging form, the chip junction temperature of the module is effectively controlled, and the laser power output performance is further improved, with a 50% increase in laser power compared to the traditional one. In future, diamond-based microfluidic heat sinks and direct wafer bonding with the Ga As substrate of the VCSEL chip will further effectively reduce thermal resistance of the module. The research will provide important reference value for thermal management of large-area and high heat flux density chips.更多还原