Femtosecond frequency comb measurement of absolute frequencies and hyperfine coupling constants in cesium vapor

TL;DR

This paper uses a femtosecond frequency comb to precisely measure absolute transition frequencies and hyperfine constants in cesium vapor, significantly improving accuracy for certain states.

Contribution

It introduces a method employing broadband femtosecond laser combs for high-precision measurements of cesium atomic states, enhancing accuracy over previous results.

Findings

Achieved two orders of magnitude improvement in measurement accuracy for 9S and 7D states.

Validated measurements of 8S state consistent with recent data.

Provided new precise values for hyperfine coupling constants.

Abstract

We report measurements of absolute transition frequencies and hyperfine coupling constants for the 8S_{1/2}, 9S_{1/2}, 7D_{3/2}, and 7D_{5/2} states in ^{133}Cs vapor. The stepwise excitation through either the 6P_{1/2} or 6P_{3/2} intermediate state is performed directly with broadband laser light from a stabilized femtosecond laser optical-frequency comb. The laser beam is split, counter-propagated and focused into a room-temperature Cs vapor cell. The repetition rate of the frequency comb is scanned and we detect the fluorescence on the 7P_{1/2,3/2} -> 6S_{1/2} branches of the decay of the excited states. The excitations to the different states are isolated by the introduction of narrow-bandwidth interference filters in the laser beam paths. Using a nonlinear least-squares method we find measurements of transition frequencies and hyperfine coupling constants that are in agreement with other recent measurements for the 8S state and provide improvement by two orders of magnitude over previously published results for the 9S and 7D states.