Tellurium Spectrometer for ${}^1\text{S}_0-{}^{1}\text{P}_1$ Transitions in Strontium and Other Alkaline-Earth Atoms

TL;DR

This paper develops a tellurium-based laser frequency reference system for strontium and other alkaline-earth atoms, enabling stable, tunable, and versatile laser spectroscopy crucial for atomic physics applications.

Contribution

It introduces a novel tellurium spectrometer setup with frequency-offset locking for precise laser tuning in alkaline-earth atom experiments, overcoming iodine's spectral density limitations.

Findings

Achieved stable, widely tunable laser frequency referencing using tellurium.

Demonstrated rapid switching between strontium isotopes in a magneto-optical trap.

Adapted the system for spectroscopy on different alkaline-earth atoms.

Abstract

We measure the spectrum of tellurium-130 in the vicinity of the 461~nm ${}^1\text{S}_0-{}^{1}\text{P}_1$ cycling transition in neutral strontium, a popular element for atomic clocks, quantum information, and quantum-degenerate gases. The lack of hyperfine structure in tellurium results in a spectral density of transitions nearly 50 times lower than that available in iodine, making use of tellurium as a laser-frequency reference challenging. By frequency-offset locking two lasers, we generate the large frequency shifts required to span the difference between a tellurium line and the ${}^1\text{S}_0-{}^1\text{P}_1$ resonance in strontium or other alkaline-earth atom. The resulting laser architecture is long-term frequency stable, widely tunable, and optimizes available laser power. The versatility of the system is demonstrated by using it to quickly switch between any strontium isotope in a magneto-optical trap and by adapting it to spectroscopy on a thermal beam with a different alkaline-earth atom.