基于法拉第效应和偏振探测技术的谱灯抽运铷原子钟方案探索

Lamp-pumped rubidium atomic clock（abbreviated as rubidium atomic clock or rubidium clock） is the preferred space atomic clock for satellite navigation systems. In the past three decades, due to the demand for satellite navigation applications, the rubidium atomic clock technology has developed rapidly, and the frequency stability has increased by nearly two orders of magnitude. Recently, we have developed a high performance lamp-pumped rubidium atomic clock with the short-term frequency stability of 2.4E-13/√τ, which is the best of the same type reported in the world. However, we also found that further improving the frequency stability of the rubidium atomic clock is difficult, because there are principle difficulties in reducing the signal background noise. We propose a new scheme for the lamp-pumped rubidium atomic clock, which utilizes the Faraday effect and polarization detection technology and can greatly reduce the background noise. This project will carry out related research on the scheme, focusing on the mechanism of influence of magnetic field strength, polarization detection angle, light intensity and microwave power on the signal-to-noise ratio (S/N) of the frequency-discrimination signal. And through parameter optimization, the S/N of the atomic signal would be improved by 2~3 times, making the lamp-pumped rubidium atomic clock short-term frequency stability reach or even exceed the level of 1E-13/√τ.

谱灯抽运铷原子钟（简称铷原子钟或铷钟）是卫星导航系统的首选星载原子钟。近三十年来，由于卫星导航应用需求的牵引，铷原子钟技术快速发展，核心指标频率稳定度提高了近2个数量级。最近我们实现了一种高信噪比铷原子钟，其短期频率稳定度达2.4E-13/√τ，是目前世界上有报道的同类铷钟最高水平。但我们同时也发现，进一步提高铷原子钟的频率稳定度面临背景光噪声难以进一步抑制这个原理性困难。我们设计了一种谱灯抽运铷原子钟的新方案，该方案基于法拉第效应和偏振检测技术，可以进一步降低背景光噪声。本项目将开展该方案的相关研究，重点探索磁场强度、偏振检测角度、光强和微波功率等参数对偏振检测鉴频信号信噪比的影响机理，通过参数优化，将使原子信号信噪比提高2~3倍，使得谱灯抽运铷原子钟的短稳有潜力达到甚至突破1E-13/√τ的水平。

谱灯抽运铷原子钟短期频率稳定度已达2.4E-13/√τ，但我们发现，进一步提高铷原子钟的频率稳定度面临背景光噪声难以进一步抑制这个原理性困难。本项目设计了一种谱灯抽运铷原子钟的新方案，该方案基于法拉第效应和偏振检测技术，可进一步降低背景光噪声。本项目对铷光谱灯的光强空间分布特性和发光光谱线型进行了研究，然后基于设计的铷钟腔泡系统，研究了传统铷钟方案下原子信号信噪比对系统频率稳定度的限制，最后研究了利用线偏振光抽运和偏振探测技术得到的原子跃迁谱线特性。项目研究表明利用提出的方案难以进一步提高铷钟稳定度性能，但利用其它方案，我们实现了将原子跃迁信号对铷钟稳定度的限制小于1E-13/√τ的水平的既定目标，并研制出一种可工程化的铷原子钟腔泡系统，可用于高性能铷钟的研制。