Two-Photon Transitions of 85Rb 5D5/2 State by Using an Optical Frequency Comb and a Continuous-Wave Laser**Supported by the National Basic Research Program of China under Grant No 2012CB921603, the Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China under Grant No IRT13076, and the National Natural Science Foundation of China under Grant Nos

Abstract

A high-resolution two-photon spectrum of 5S1/2 → 5P3/2 → 5D5/2 transitions in a thermal 85Rb vapor cell is presented by using an optical frequency comb and a cw laser. The fluorescence of 6P3/2 → 5S1/2 spontaneous emission is detected when the cw laser frequency is scanned from the 5S1/2 ground state to 5P3/2 hyperfine levels and the optical frequency comb repetition rate is fixed. The hyperfine splittings (Ff = 2–5) of the 5D5/2 excited state are well resolved. The dependences of fluorescence intensities on the cw laser intensity and temperature of 85Rb vapor cell are studied, respectively. The experimental results are in good agreement with the theoretical analyses.