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针对铷原子能级跃迁对光谱的特殊需求,设计并制备了795 nm单模垂直腔面发射激光器(VCSEL)。根据对VCSEL的光场和模式的分析和计算结果,设计了单模VCSEL芯片结构。采用MOCVD技术生长了外延结构,制备了不同有源区直径的氧化限制型VCSEL芯片并进行了测试。当有源区直径从6μm减小到3μm时,VCSEL芯片的边模抑制比(SMSR)由8.76 d B增加到34.05 d B,阈值电流由0.77 m A减小到0.35 m A。有源区直径为6,5,4和3μm的VCSEL芯片的输出功率分别为0.37,0.46,0.58和0.44 m W,有源区直径为4μm的VCSEL芯片的远场为圆形光束,发散角为15°。85℃时3.5μm有源区直径的VCSEL芯片输出功率为0.125 m W,激射波长为795.3 nm。室温3 d B带宽大于8 GHz,满足了铷原子传感器对VCSEL单模光谱、输出功率及调制速率的要求。
Aiming at the special requirement of spectrum for rubidium atom level transition, a 795 nm single mode vertical cavity surface emitting laser (VCSEL) was designed and fabricated. According to the analysis and calculation results of VCSEL’s light field and mode, a single-mode VCSEL chip structure is designed. Epitaxial structure was grown by MOCVD technique, and the oxidized confinement VCSEL chips with different active area diameters were prepared and tested. When the active region diameter is reduced from 6μm to 3μm, the side mode suppression ratio (SMSR) of VCSEL chip increases from 8.76 d B to 34.05 d B, and the threshold current decreases from 0.77 m A to 0.35 m A. VCSEL chips with active regions of 6, 5, 4, and 3 μm in diameter have output powers of 0.37, 0.46, 0.58, and 0.44 mW, respectively. The VCSEL chip with active region diameter of 4 μm is a circular beam with a divergent angle of 15 °. The VCSEL chip with 3.5μm active area diameter at 85 ℃ has an output power of 0.125 mW and a lasing wavelength of 795.3 nm. Room temperature 3 d B bandwidth greater than 8 GHz, to meet the rubidium atomic sensor VCSEL single-mode spectrum, output power and modulation rate requirements.