A Laser System for the Spectroscopy of Highly-Charged Bismuth Ions

TL;DR

This paper introduces a laser system designed for high-precision spectroscopy of highly-charged bismuth ions at 244 nm, utilizing advanced stabilization and tuning techniques for accurate frequency control.

Contribution

The work presents a novel laser stabilization scheme with extended tuning range and high frequency accuracy for UV spectroscopy of highly-charged ions.

Findings

Achieved frequency uncertainty of 6.14 MHz at 244 nm over six days.

Implemented a transfer cavity locking scheme for stable laser frequency.

Extended tuning range of several THz using a sample-and-hold technique.

Abstract

We present and characterize a laser system for the spectroscopy on highly-charged ^209Bi^82+ ions at a wavelength of 243.87 nm. For absolute frequency stabilization, the laser system is locked to a near-infra-red laser stabilized to a rubidium transition line using a transfer cavity based locking scheme. Tuning of the output frequency with high precision is achieved via a tunable rf offset lock. A sample-and-hold technique gives an extended tuning range of several THz in the UV. This scheme is universally applicable to the stabilization of laser systems at wavelengths not directly accessible to atomic or molecular resonances. We determine the frequency accuracy of the laser system using Doppler-free absorption spectroscopy of Te_2 vapour at 488 nm. Scaled to the target wavelength of 244 nm, we achieve a frequency uncertainty of \sigma_{244nm} = 6.14 MHz (one standard deviation) over six days of operation.