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

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 3 P 2 state and the 9.8 MHz broad 5s5p 3 P 2 → 5s5d 3 D 3 transition might be of interest for sub-Doppler cooling.

Visible‐Light Laser Diodes and Superluminescent Diodes: Characteristics and Applications

“…However, in the absence of an external cavity, a laser diode would be required for spectroscopy due to its narrow spectral emission. Laser cooling, which also requires precise control over the emission spectrum, might also make use of external cavities and injection locking [69][70][71][72].…”

A simple, powerful diode laser system for atomic physics

“…This generally results in a device with high tunability and narrow linewidth at a reasonable cost. The atomic or molecular species and transition of interest determines the choice of components, particularly the laser diode and grating, however a wide range of wavelengths are accessible from home-made ECDLs for assisting laser cooling of K at 405 nm [25] or Sr at 497 nm [26], to compact ECDLs for water vapor absorption at 1.4 µm [27].…”