1 中国科学院上海光学精密机械研究所量子光学重点实验室，上海 201800
2 中国科学院大学，北京 100049
介绍了一种利用光锁相环技术实现频率稳定的深紫外激光系统，包含两台253.7 nm四倍频激光器，用于汞原子在二维磁光阱和三维磁光阱的激光冷却。其中，一台深紫外激光器锁定在汞原子的饱和吸收谱线上，用于产生二维磁光阱的冷却光和推送光；另一台深紫外激光器通过1014.9 nm的半导体种子激光之间的光锁相环实现频率稳定，用于产生三维磁光阱的冷却光和探测光，并通过前馈方法将频率切换时间减小到原来的1/23。该系统可以大范围地调整深紫外激光器的频率，高效地利用紫外激光功率，并降低了实验装置的复杂性，从而满足了汞原子激光冷却实验的要求。同时，所提方法适用于其他深紫外激光系统。
激光器 汞原子 激光冷却 深紫外激光 光锁相环
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
