A simplified 461-nm laser system using blue laser diodes and a hollow cathode lamp for laser cooling of Sr

TL;DR

This paper presents a simplified 461 nm laser system for Sr laser cooling using blue laser diodes and a hollow cathode lamp, eliminating the need for frequency-doubling crystals, which is significant for portable optical lattice clocks.

Contribution

The work introduces a simplified laser setup at 461 nm employing blue laser diodes and polarization spectroscopy, enhancing portability for Sr laser cooling applications.

Findings

Achieved 40 mW output power at 461 nm with an external cavity diode.

Amplified laser power to 110 mW via injection locking.

Demonstrated stable frequency locking using polarization spectroscopy.

Abstract

We develop a simplified light source at 461 nm for laser cooling of Sr without frequency-doubling crystals but with blue laser diodes. An anti-reflection coated blue laser diode in an external cavity (Littrow) configuration provides an output power of 40 mW at 461 nm. Another blue laser diode is used to amplify the laser power up to 110 mW by injection locking. For frequency stabilization, we demonstrate modulation-free polarization spectroscopy of Sr in a hollow cathode lamp. The simplification of the laser system achieved in this work is of great importance for the construction of transportable optical lattice clocks.