795 nm VCSELs for 87Rb based miniaturized atomic clock
795 nm VCSELs for 87Rb based miniaturized atomic clock
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用于基于 87Rb 的小型原子钟的 795 nm VCSEL
DOI：
10.3788/ope.20142201.0050
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Wang, Li-Jun
中科院分区：
文献类型：
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作者：
Zhang, Jian-Wei;Zhang, Xing;Zeng, Yu-Gang;Wang, Li-Jun
针对87 Rb原子钟小型化和高温对激发源的特殊要求，设计并制作了一台795 nm垂直腔面发射激光器（VCSEL），该激光器对应于Rb原子能级跃迁。首先，采用kp方法计算了InAlGaAs/AlGaAs多量子威尔斯阱（MQW）的能级和材料增益，优化了量子威尔斯阱的组分和厚度。设计了795 nm的分布布拉格反射器（DBR），并采用一维传输矩阵法对DBR的反射特性、纵向光场和平均掺杂分布进行了计算和优化。最后，采用金属有机气相外延（MOVPE）技术在GaAs衬底上生长了优化多量子阱和DBR的795 nm垂直腔面发射激光器的外延结构，并制备了氧化物限制的非闭合台面结构的795 nm顶发射垂直腔面发射激光器。实验结果表明，在25 ~ 85 C的连续工作电流下，封装后的VCSEL能够保持激光输出，输出功率从17 mW下降到1.8 mW，远场分布为发散角为15 °的圆形，激光波长的温漂为0.064 nm/C。在室温52 ℃、电流100 mA时，激光波长达到87 Rb原子所需的波长。795 nm VCSEL满足了基于87 Rb的小型化原子钟在特定波长和高温下稳定工作的基本要求。
For the special requirements of the exciting source of a 87Rb based atomic clock for the miniaturization and high temperature conditions, a 795 nm Vertical Cavity Surface Emitting Laser(VCSEL)corresponding to the Rb atom energy level transition was designed and fabricated. Firstly, the energy levels and material gains of the InAlGaAs/AlGaAs Multiple Quantum Wells (MQWs) were calculated by the kp method to optimize the compositions and thicknesses of the quantum wells. Then, a Distributed Bragg Reflectors(DBRs) at 795 nm were designed and their reflection characteristics, longitudinal optical fields and averaged doping profiles were calculated and optimized using a one-dimensional transfer matrix method. Finally, the epitaxial structure of the 795 nm VCSEL with optimized MQWs and DBRs were grown on a GaAs substrate by Metal Organic Vapor Phase Epitaxy (MOVPE) and the oxide-confined 795 nm top-emitting VCSELs with unclosed-mesa structures were fabricated and characterized. Experimental results indicate that the packaged VCSELs can keep lasing under a cw current from 25 C to 85 C with power decreasing from 17 mW to 1.8 mW, the far field profiles are circular with a divergence angle of 15 and the temperature-shift of the lasing wavelength is 0.064 nm/C. Moreover, the lasing wavelength moves to the wavelength required by 87Rb atoms at an ambient temperature of 52 C and a current of 100 mA. The 795 nm VCSELs satisfy the basic requirements of 87Rb based miniaturized atom clocks for stable operation in a special wavelength and high-temperatures.