A tunable low-drift laser stabilized to an atomic reference

TL;DR

This paper introduces a laser system with high frequency stability and low drift, stabilized to an atomic reference, suitable for precision spectroscopy of ions at 441 nm.

Contribution

It demonstrates a tunable, low-drift laser stabilized to an atomic transition with detailed characterization of its stability and linewidth.

Findings

Linewidth of 50 kHz achieved

Long-term frequency stability verified against an atomic reference

Laser suitable for high-precision ion spectroscopy

Abstract

We present a laser system with a linewidth and long-term frequency stability at the 50 kHz level. It is based on a Ti:Sapphire laser emitting radiation at 882 nm which is referenced to an atomic transition. For this, the length of an evacuated transfer cavity is stabilized to a reference laser at 780 nm locked to the $^{85}$Rb D$_2$-line via modulation transfer spectroscopy. Gapless frequency tuning of the spectroscopy laser is realized using the sideband locking technique to the transfer cavity. In this configuration, the linewidth of the spectroscopy laser is derived from the transfer cavity, while the long-term stability is derived from the atomic resonance. Using an optical frequency comb, the frequency stability and linewidth of both lasers are characterized by comparison against an active hydrogen maser frequency standard and an ultra-narrow linewidth laser, respectively. The laser system presented here will be used for spectroscopy of the $1s^{2}2s^{2}2p\ ^{2}P_{1/2} -\ ^{2}P_{3/2}$ transition in sympathetically cooled Ar$^{13+}$ ions at 441nm after frequency doubling.