Injection locking of a low cost high power laser diode at 461 nm

TL;DR

This paper demonstrates injection locking of a high-power blue laser diode at 461 nm, achieving stable, narrow-band emission suitable for optical cooling of strontium atoms, offering an alternative to frequency doubling methods.

Contribution

It shows that low-power monomode laser injection can effectively lock a high-power multimode diode at 461 nm, reducing bandwidth and enabling direct use in atomic cooling applications.

Findings

At least 50% of the diode's power is locked to the desired frequency.

Bandwidth reduction verified by saturation spectroscopy and beat measurements.

Laser used successfully in a Zeeman slower for strontium cooling.

Abstract

Stable laser sources at 461 nm are important for optical cooling of strontium atoms. In most existing experiments this wavelength is obtained by frequency doubling infrared lasers, since blue laser diodes either have low power or large emission bandwidths. Here, we show that injecting less than 10 mW of monomode laser radiation into a blue multimode 500 mW high power laser diode is capable of slaving at least 50% of the power to the desired frequency. We verify the emission bandwidth reduction by saturation spectroscopy on a strontium gas cell and by direct beating of the slave with the master laser. We also demonstrate that the laser can efficiently be used within the Zeeman slower for optical cooling of a strontium atomic beam.