An extended-cavity diode laser at 497 nm for laser cooling and trapping of neutral strontium

TL;DR

This paper reports the development of the first extended-cavity diode laser at 497 nm, offering a compact, tunable, single-frequency source for strontium laser cooling and trapping, simplifying existing complex systems.

Contribution

Introduction of the first 497 nm extended-cavity diode laser with high power, tunability, and narrow linewidth for atomic physics applications.

Findings

Up to 60 mW output power at 497 nm.

Tunable over more than 8 nm.

Lorentzian linewidth less than 90 kHz.

Abstract

We present the first extended-cavity diode laser in Littrow configuration operating in the cyan wavelength range around 497 nm. The gallium-nitride based diode laser features a free-space output with up to 60 mW, operates in a single frequency mode, is tunable over a range of more than 8 nm and has a Lorentzian linewidth of less than 90 kHz. A detailed characterization of the tuning capabilities of the diode laser and its emission spectrum is provided. This compact, simple and low cost laser source replaces more complex systems based on frequency doubling and therefore simplifies the development of future compact and mobile optical clocks based on neutral strontium. Applications include efficient repumping of strontium atoms from the $5s5p$ $^3P_2$ state and the 9.8 MHz broad $5s5p$ $^3P_2 \rightarrow 5s5d$ $^3D_3 $ transition might be of interest for sub-Doppler cooling.