1 中国科学院上海光学精密机械研究所, 上海 201800
2 中国科学院大学, 北京 100049
3 中国科学院量子光学重点实验室, 上海 201800
光晶格钟需要高稳定度的超稳激光, 而超稳激光的频率稳定性受限于超稳腔的热噪声和温度涨落, 因此, 降低超稳腔的温度涨落对于超稳激光的频率噪声达到热噪声极限具有重要意义。分别从时域和频域上分析了达到热噪声极限对超稳腔温度稳定性的要求, 设计了超稳腔控温系统, 其包括一层被动隔热、两层主动控温的超稳腔真空系统和主动控温装置; 找到了超稳腔的零膨胀工作温度; 测量了真空隔热系统的温度传递时间常数(3.6 d); 监测了真空腔内主动控温层11 d的温度涨落(<1 mK)。通过实验测量和理论分析, 在频域和时域上分别计算得到了超稳腔的温度波动, 确定了千秒内的温度涨落引起的频率噪声均在热噪声极限以下。利用磁光阱产生的199Hg冷原子的钟频跃迁光谱测得超稳腔的长期温度漂移为4.2 kHz/d, 符合Hg原子光晶格钟的要求。
激光光学 超稳激光 温度稳定 钟频跃迁 长期漂移
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Key Laboratory of Quantum Optics, Chinese Academy of Sciences, Shanghai 201800, China
3 University of Chinese Academy of Sciences, Beijing 100049, China
4 Center of Cold Atom Physics, Chinese Academy of Sciences, Shanghai 201800, China
We report on the observation of the highly forbidden S10–P30 optical clock transition in laser-cooled Hg199 atoms. More than 95% depletion of cold Hg199 atoms is detected in the magneto-optical trap. Using the free-of-field detection method, the AC Stark shift from the cooling laser is removed from the in-field spectroscopy. At low-power clock laser pumping, the linewidth of the clock spectroscopy is approximately 450 kHz (full width at half-maximum), which corresponds to a Doppler broadening at the atom temperature of 60 μK. We determine the S10–P30 transition frequency to be 1,128,575,290.819(14) MHz by referencing with a hydrogen maser and measuring with a fiber optical frequency comb. Moreover, a weak Doppler-free signal is observed.
020.1335 Atom optics Chinese Optics Letters
2018, 16(6): 060202
1 中国科学院上海光学精密机械研究所, 上海 201800
2 中国科学院量子光学重点实验室和冷原子物理中心, 上海 201800
3 中国科学院大学, 北京 100049
详细介绍了基于1014.8 nm室温光纤激光放大器的高效外腔倍频技术, 获得了大功率的507.4 nm单频激光。高效的外腔倍频是由内置正入射三硼酸锂晶体的高增益环形腔实现的, 最高可以获得3 W的输出功率, 倍频效率高达61.5%。倍频腔输入输出功率的实验测量值与理论计算结果相符合。该倍频腔针对4 W的基频光输入设计, 在最佳工作点(4W)附近倍频效率对输入功率改变不敏感。在1.5 h内, 绿光输出功率涨落的均方根值为1.7%。大功率稳定输出的507.4 nm单频激光可通过偏硼酸钡晶体倍频产生用于冷却中性汞原子所需的253.7 nm深紫外激光, 也可直接用于探测镱原子1S0态到3P2态跃迁的光谱和相关实验。
激光光学 绿光 二次谐波产生 环形腔 三硼酸锂晶体 非线性光学
Author Affiliations
Abstract
1 Key Laboratory for Quantum Optics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Science, Beijing 100049, China
3 Center for Cold Atom Physics, Chinese Academy of Sciences, Shanghai 201800, China
We experimentally observe polarization spectroscopy (PS) of the S01-P31 transition of mercury atom gases at 253.7 nm. The PS signal can be observed in all six richly abundant isotopes and the PS signal of six transitions for laser cooling are all clear and of a dispersive line shape. The optimized pump power and probe power are found for the PS of Hg202. We find the linearly polarized component in the pump beam will distort the original PS signal due to the use of linear PS. Consequently, the purity of the pump beam is crucial to laser frequency stabilization by PS.
300.6210 Spectroscopy, atomic 300.6310 Spectroscopy, heterodyne Chinese Optics Letters
2015, 13(7): 073001
1 中国科学院上海光学精密机械所中国科学院量子光学重点实验室, 中国科学院冷原子物理中心, 上海 201800
2 中国科学院大学, 北京 100049
3 中国科学院上海高等研究院, 上海 201203
连续可调谐的紫外激光一般通过红外或可见激光进行外腔倍频获得，然而倍频腔锁定电路的带宽限制了激光器的调谐性能。将前馈控制方法用于中性汞原子激光冷却的四倍频紫外激光器，即在调谐基频激光频率的同时，同步调节级联的两个倍频腔。这不仅降低了激光器频率调谐中引入的功率噪声，还提高了紫外激光器的频率调谐范围，使得紫外激光器的调谐能力得到大幅提高。通过汞原子的亚多普勒磁致双色光谱进行激光频率锁定，发现前馈控制电路的应用能降低激光的频率噪声。在汞原子光谱和激光冷却实验中，紫外激光的可调谐性和稳定性的提高将会带来很多优势。
激光器 四倍频 前馈控制方法 中性汞原子 激光冷却 相对功率噪声 中国激光
2014, 41(12): 1202004
