Two-color modulation transfer spectroscopy

TL;DR

This paper introduces two-color modulation transfer spectroscopy, a precise method for studying excited atomic states with high resolution, useful for measuring energy splittings and stabilizing laser frequencies.

Contribution

The paper presents a novel two-color modulation transfer spectroscopy technique that achieves sub-Doppler resolution and in situ energy spacing measurement for excited atomic states.

Findings

Achieves sub-Doppler linewidths in atomic spectra

Provides high signal-to-noise ratio spectra

Includes in situ rulers for energy spacing

Abstract

We present two-color modulation transfer spectroscopy as a tool for precision studies of atomic properties of excited states. The bi-colored technique addresses a narrow set of velocity groups of a thermal atomic vapour using a two-step transition to "burn a hole" in the velocity distribution. The resulting spectrum presents sub-Doppler linewidths, good signal to noise ratio and the trademark sidebands that work as an in situ ruler for the energy spacing between atomic resonances. The spectra obtained can be used for different applications such as measurements of energy splittings or stabilization of laser frequencies to excited atomic transitions.