Optical frequency measurements of 6s2S1/2 - 6p2P3/2 transition in a 133Cs atomic beam using a femtosecond laser frequency comb

Abstract

Optical frequencies of the hyperfine components of the D2 line in 133Cs are determined using high-resolution spectroscopy and a ferntosecond laser frequency comb. A narrow-linewidth probe laser excites the 6s 2 S1/2 (F=3, 4)→ 6p2 P 3/2 (F=2,3, 4, 5) transition in a highly collimated atomic beam. Fluorescence spectra are taken by scanning the laser frequency over the excited-state hyperfine structure. The laser optical frequency is referenced to a Cs fountain clock via a reference laser and a ferntosecond laser frequency comb. Aretroreflectedlaser beam is used to estimate and minimize the Doppler shift due to misaligmnent betweenthe probe laser and the atomic beam. Weachieve an angular resolution on the order of 5X10-6 rad. The final uncertainties (~±5 kHz) in the frequencies of the optical transitions are a factor of 20 better than previous results [T.Udem et aI., Phys. Rev. A 62, 031801 (2000).]. Wefind the centroid of the 6s 28112 → 6p2 P 3/2 transitionto be fm~351 725718.4744(51) MHz.