利用传输腔技术实现镱原子光钟光晶格场的频率稳定  

Transfer cavity scheme for stabilization of lattice laser in ytterbium lattice clock

作　　者：张曦[1,2,3] 刘慧[1,2,3] 姜坤良[1,2,3] 王进起 熊转贤[1,2] 贺凌翔[1,2] 吕宝龙[1,2] 

机构地区：[1]中国科学院武汉物理与数学研究所,波谱与原子分子物理国家重点实验室,武汉430071 [2]中国科学院原子频标重点实验室,武汉430071 [3]中国科学院大学,北京100049

出　　处：《物理学报》2017年第16期126-131,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61227805,11574352,91536104,91636215);B类战略性先导科技专项(批准号:XDB21030700)资助的课题~~

摘　　要：为了获得高稳定度和高精确度的原子光晶格钟,光晶格场的频率必须得到锁定,线宽必须控制到特定水平用来消除交流斯塔克频移.本文提出利用传输腔技术来实现对镱原子光钟的光晶格场的频率锁定和抑制频率长期漂移的锁定方案.首先,将一个殷钢材料的传输腔锁定在基于调制转移谱技术锁定的780 nm激光场上,再将759 nm的光晶格光场锁定在传输腔上.实验结果表明,光晶格光场的线宽可以锁定和控制在1 MHz以下.光晶格光场与锁定于氢钟的光梳拍频结果显示,光晶格光场的长期频率稳定度优于3.6×10^(-10),可以确保实现镱原子光钟的不确定度进入10^(-17).For high performance clock, optical lattice is introduced to generate periodic trap for capturing neutral atoms through weak interactions. However, the strong trapping potential can bring a large AC Stark frequency shift due to imbalance shifts for the upper and lower energy levels of the clock transition. Fortunately, it is possible to find a specific＂magic＂wavelength for the lattice light, at which the first-order net AC Stark shift equals zero. To achieve high stability and accuracy of a neutral atomic optical clock, the frequency of the lattice laser must be stabilized and controlled to a certain level around magic wavelength to reduce this shift. In this paper, we report that the frequency of lattice laser is stabilized and linewidth is controlled below 1 MHz with transfer cavity scheme for ytterbium （Yb） clock. A confocal invar transfer cavity mounted in an aluminum chamber is locked through the Pound-Drever-Hall （PDH） method to a 780 nm diode laser stabilized with modulation transfer spectroscopy of rubidium D2 transition. It is then used as the locking reference for the lattice laser. This cavity has a free spectral range of 375 MHz, as well as fineness of 236 at 780 nm, and 341 at 759 nm. Because neither of the wavelengths of 759 nm and 780 nm is separated enough to use optical filter, they are coupled into the cavity with transmission and reflection way respectively, and the two PDH modulation frequencies are chosen differently to avoid possible interference. The stabilization of the 759 nm lattice laser on transfer cavity can stay on for over 12 hours without escaping or mode hopping. To estimate the locking performance of the system, a beat note with a hydrogen maser-locked optical frequency comb is recorded through a frequency counter at 10 ms gate time for over 3 hours. This beat note shows that the frequency fluctuation is in a range of 10 kHz corresponding to a stability of 2 × 10？11 level with 0.1 s averaging time, but goes up to 150 kHz corresponding to a stability of 3.6 × 10？

关 键 词：镱原子光钟 光晶格场 传输腔 频率稳定度 

分 类 号：O562[理学—原子与分子物理]