Two-photon two-color diode laser spectroscopy of the Rb 5<i>D</i>_5/2state

Abstract

We report on spectroscopic measurements of the Rb 5D5/2 state performed using two-photon excitation with a resonant intermediate state. With the two beams (5S1/2 → 5P3/2 at 780 nm and 5P3/2 → 5D5/2 at 776 nm) counterpropagating, the spectra are Doppler-free and the signals are very robust, even in a room temperature vapor. This is due to the near match of the transition wavelengths. The 5D5/2 hyperfine constants have been measured and compared to previous determinations. We have also performed the excitation in a sample of laser-cooled atoms and compare these results to those obtained at room temperature. The fact that the 5P3/2 → 5D5/2 transition is narrow, robust, diode-laser accessible, and relatively immune to AC-Stark shifts, may make it a promising candidate for a frequency reference at 776 nm.