Doppler-free spectroscopy of molecular iodine using a frequency-stable light source at 578 nm

TL;DR

This paper develops a stable, frequency-locked light source at 578 nm using sum-frequency generation for high-resolution molecular iodine spectroscopy, achieving high stability and precise frequency measurement for optical clock applications.

Contribution

A novel frequency-stable light source at 578 nm based on sum-frequency generation is demonstrated, enabling high-resolution iodine spectroscopy and precise frequency referencing.

Findings

Achieved a stability of 2×10^-12 at 1 second.

Measured the absolute frequency of a hyperfine transition with 2 kHz accuracy.

Provided a frequency reference for ytterbium optical clocks.

Abstract

A stable light source obtained using sum-frequency generation (SFG) is developed for high-resolution spectroscopy at 578 nm. Hyperfine transitions of molecular iodine are observed by using the SFG light source with saturation spectroscopy. The light source is frequency stabilized to the observed hyperfine transition and achieves a stability of 2*10-12 for a 1-s averaging time. The absolute frequency of the light source stabilized on the a1 component of the R(37)16-1 transition is determined as 518304551833 (2) kHz. This transition serves as a frequency reference for the 1S0 - 3P0 optical clock transition in neutral ytterbium (Yb).