摘要
铷87的双光子光谱具有高信噪比、无多普勒展宽、窄线宽等特点。构建了基于87Rb原子双光子跃迁的光学频率参考,分析测试了影响其短期稳定度的因素。利用778 nm外腔半导体激光器激发双光子跃迁产生420 nm荧光信号,通过荧光信号锁定激光器频率。探讨了谱线线宽、信噪比、功率、温度相关的谱线展宽、光频移、系统结构稳定性和调制宽度等对频移和稳定度的影响。采用螺栓锁紧结构固定光学元件,大幅改善了光学对准引起的稳频误差,通过直接调制激光器电流实现了秒级稳定度为1.5×10^(-12)、500 s稳定度为2.88×10^(-13)的光学频率参考。与其他基于饱和吸收的光学频率参考相比,构建的基于87Rb原子双光子跃迁的光学频率参考的稳定度提高了10~100倍。光学对准对于提高荧光探测信噪比和优化长期稳定度具有重要意义。验证了内调制实现双光子光学频率参考的可行性,并提出了进一步优化短期稳定度和长期稳定度可采用的技术方案。
Objective Rubidium(Rb)atomic two-photon spectra have attracted great attention in connection with small atomic frequency standards due to their narrow linewidth,absence of Doppler background,and broadening characteristics.In the past few decades,extensive research has been conducted on Rb atomic two-photon spectroscopy.As early as the 1990s,F.Nez et al.measured the absolute frequency of the two-photon transition with an uncertainty of 1.3×10^(-11).In 1994,Y.Millerioux et al.locked two lasers to the relevant hyperfine levels using Rb atomic two-photon transitions and achieved an instability of 3×10^(-13)in the 2000 s.In 2000,J.E.Bernard et al.used a frequency-doubled 1556 nm laser to precisely measure the two-photon transition frequency with a stability of 4×10^(-13) in 200 s.In 2020,Vincent Maurice et al.demonstrated a two-photon transition frequency standard on a micro-optical substrate using a miniature gas cell,achieving an instability of 2.9×10^(-12) at 450 mW power for 1 s.In 2021,Zachary L.Newman et al.reported a two-photon frequency standard at NIST with an instability of 1.8×10^(-13) in 100 s averaging time.The Rb two-photon optical frequency standard has the advantages of compactness and high precision,and with the support of micro-comb technology,it is expected to be adaptable to a wider range of application scenarios to become the next-generation high-performance atomic clock.Therefore,it is necessary to investigate this two-photon optical reference with compact volume and high performance.Methods We conducted a two-photon fluorescence spectroscopy experiment using a high-purity 87Rb vapor cell and a 778.1 nm laser.The laser was generated by an external cavity diode laser(ECDL)and stabilized by direct current modulation.The laser was split into two beams by a polarization beam splitter(PBS)and coupled into single-mode polarization-maintaining fibers.One beam was used to excite the atoms in the vapor cell,which was heated to 110℃,and the other beam was used as a reference for the beat frequency m
作者
孟一鸣
项静峰
徐斌
李彪
万金银
任伟
邓思敏达
张迪
吕德胜
Meng Yiming;Xiang Jingfeng;Xu Bin;Li Biao;Wan Jinyin;Ren Wei;Deng Siminda;Zhang Di;LüDesheng(Spaceborne Laser Engineering Department,Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Key Laboratory of Quantum Optics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2023年第23期113-120,共8页
Chinese Journal of Lasers
关键词
激光器
双光子跃迁
激光稳频
光学对准
频率稳定度
laser
two-photon transition
laser frequency stabilization
optical alignment
frequency stability
