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大功率垂直腔面发射激光器(VCSEL)在激光泵浦、激光测距、激光雷达等领域有广泛的应用前景,但目前的常规激光器材料结构尚未针对大功率激光输出进行优化设计。特别是为获得大功率激光输出所采用的大出光窗口导致的激光光束质量劣化成为限制其应用发展的核心问题之一。针对上述问题对激光器材料结构与器件结构进行了两方面的新结构设计和研制:(1)以实现大功率激光输出为目标,材料结构设计上对出光窗口一侧的N-DBR反射率进行了调整,以具有99.3%反射率的n-DBR替代常规结构中所采用的99.7%以上反射率。与常规材料结构相比,采用优化后的材料结构制备的直径500μm出光孔径的单管器件在注入电流110 A时激光输出功率达到102 W,而单元出光窗口直径100μm的5×5阵列在100 A电流下的激光输出功率为103 W,单元直径为140μm的8×8阵列在130 A注入电流下的激光输出功率达到115 W;(2)针对大出光窗口导致的光束质量劣化,通过湿法化学刻蚀研制了直接集成在出光窗口表面的微透镜结构,单元出光窗口直径为90μm的6×6阵列器件在4 A注入电流下的激光光束发散角压缩到6.6°,与未集成微透镜时的14.8°相比有了大幅改善。实验结果表明:降低n-DBR反射率及集成微透镜结构有效地改善提高了大功率垂直腔面发射激光的输出功率和激光光束质量。
High power vertical cavity surface emitting lasers (VCSELs) have broad application prospects in the fields of laser pumping, laser ranging, laser radar, etc. However, the conventional laser material structures have not been optimized for high power laser output. Especially, the laser beam quality degradation caused by the large light-emitting window adopted for obtaining high-power laser output has become one of the core problems restricting the application development. In order to achieve the high-power laser output, a new structural design and development of the laser material structure and device structure are carried out according to the above problems: (1) N-DBR reflectivity on the light exit side of the material structure design The n-DBR with 99.3% reflectance was adjusted to reflect over 99.7% of the reflectivity used in conventional structures. Compared with the conventional material structure, the single-tube device with the 500μm diameter of the light-emitting aperture prepared by the optimized material structure achieves a laser output power of 102 W at an injection current of 110 A, and a 5 × 5 array with a 100 μm Laser output power of 103 W at current and 8 × 8 array with unit diameter of 140 μm reached 115 W at 130 A injection current; (2) Beam quality degradation caused by large light exit window, The micro-lens structure directly integrated on the surface of the light-emitting window was developed by etching. The laser beam divergence angle of the 6 × 6 array device with the light-emitting window diameter of 90μm was compressed to 6.6 ° under the injection current of 4 A, 14.8 ° compared to a significant improvement. The experimental results show that reducing the n-DBR reflectivity and integrating the micro-lens structure effectively improves the output power and the laser beam quality of the high-power vertical-cavity surface-emitting laser.