【作者】 刘杰；

【导师】 邹林儿；

【作者基本信息】 南昌大学 ， 物理学， 2025， 硕士

【摘要】 小铯钟作为一级频率标准,在国防、通信、导航、授时等领域应用广泛。光抽运小铯钟因其更高的原子利用率,较磁选态小铯钟更具指标优势。激光系统为光抽运小铯钟的重要组成部分,性能影响光抽运小铯钟的频率稳定度等指标。光抽运小铯钟要求激光系统输出频率稳定、功率波动低的激光,以保证铯原子能级制备和钟跃迁信号的检测效果。但激光稳频效果易受外界环境影响、自由运转的激光功率波动大等因素一度限制了光抽运小铯钟的工程化进程。本论文对光抽运小铯钟所用的激光系统进行了深入研究,采用原子束荧光稳频技术与基于声光调制器的激光功率稳定技术,分别对激光频率和激光功率进行伺服控制,研制了一套小型化激光系统,经测试,性能满足光抽运小铯钟使用要求。本论文的主要工作有:1.分析了光抽运小铯钟激光与原子之间的相互作用机制,重点讨论了抽运光与检测光所对应跃迁路径的物理特性及其对钟信号提取效率的影响,确定了本研究抽运光与检测光的配置方案,为后续激光系统设计与实验研究奠定了基础。2.针对激光频率漂移问题,研制基于原子束荧光稳频技术的激光系统,以自主设计的高稳激光二极管驱动电路和高精度铯炉控温电路为基础,获得了高度稳定的稳频荧光信号。结合激光频率锁定电路,实现了秒稳2.01×10?11和线宽2.5MHz的稳频激光输出。3.针对激光功率波动大的问题,构建基于声光调制器的激光功率动态调控系统,系统采用声光调制器作为执行器件,闭环控制其驱动信号功率,降低激光功率波动。测试结果表明,该系统将激光相对功率波动抑制至±0.1%,标准差降至0.05%。4.采用光机一体化设计方案,集成DFB激光器、光学元器件与电路模块,通过有限元仿真优化抗振结构,实现了激光系统。该系统支撑实现了高性能光抽运小铯钟,实测整钟千秒频率稳定度达1.99×10^-13。更多还原

【Abstract】 As a primary frequency standard,compact cesium clocks are widely employed in defense,communications,navigation,and timekeeping.Compact optically pumped cesium clocks exhibit superior performance metrics compared to magnetic state-selected cesium clocks due to their higher atomic utilization efficiency.The laser system,a critical component of optically pumped cesium clocks,significantly influences key parameters such as frequency stability.These clocks require lasers with stable frequency and low power fluctuations to ensure effective preparation of cesium atomic energy levels and detection of clock transition signals.However,challenges including environmental susceptibility of laser frequency stabilization and significant power fluctuations in free-running lasers have historically hindered the engineering advancement of optically pumped cesium clocks.This thesis conducts a comprehensive study on the laser system for optically pumped compact cesium clocks.By integrating atomic beam fluorescence frequency stabilization and acousto-optic modulator(AOM)-based laser power stabilization technologies,we developed a miniaturized laser system with servo-controlled frequency and power.Experimental validation confirms that the system meets the operational requirements for optically pumped cesium clocks.The main contributions of this work are as follows:1.A systematic analysis of the laser-atom interaction mechanisms in optically pumped compact cesium atomic clocks was conducted,with a focused investigation into the spectroscopic characteristics of transition pathways associated with pump and probe lights,as well as their impact on clock signal detection efficiency.This study established optimized configuration parameters for the pump and probe light schemes,providing a critical theoretical foundation for subsequent laser system design and experimental investigations.2.To address laser frequency drift,a laser frequency stabilization system based on atomic beam fluorescence spectroscopy was developed.Leveraging a custom-designed high-stability laser diode driver circuit and a precision cesium oven temperature control system(thermal stability:±0.01°C),ultra-stable frequency-stabilized fluorescence signals were obtained.By integrating a laser frequency locking circuit,the system achieved a frequency-stabilized laser output with 1-second fractional frequency stability of 2.01×10?11and a spectral linewidth of 2.5 MHz,fulfilling the stringent requirements for atomic state manipulation in cesium clock applications.3.To address the issue of significant laser power fluctuations,a dynamic laser power stabilization system based on an AOM was constructed.The system employs the AOM as an actuator and implements closed-loop control of its drive signal power to suppress laser power instability.Experimental results demonstrate that this system effectively reduces relative laser power fluctuations to within±0.1%,with the standard deviation diminished to 0.05%.4.An opto-mechanical integrated design approach was implemented to realize a compact laser system through the incorporation of distributed feedback(DFB)lasers,precision optical components,and electronic modules.Vibration-resistant mechanical structures were optimized via finite element analysis(FEA)simulations to ensure environmental robustness.This system enabled the development of a high-performance optically pumped compact cesium atomic clock,achieving a measured fractional frequency stability of 1.99×10?13at 1,000-second averaging time—a benchmark performance for miniature atomic frequency standards.更多还原