Watt-class injection-locked diode laser system at 399 nm for atomic physics

We are constructing an ytterbium atom interferometer to search for ultralight dark matter. This device will be sensitive to scalar, pseudoscalar, and vector dark matter couplings in the frequency range of $10^{-8}$ Hz to $10$ Hz. Here we present an injection-locked 399~nm laser system used for cooling and trapping ytterbium atoms for our experiment. The system consists of a 5~mW seed laser and a follower laser that delivers up to 1.5~W. The locked high-power laser inherits the frequency agility and linewidth of the seed laser with $3.9~\text{kHz}$ broadening. By performing spectroscopy on a cold atomic beam of ytterbium, we show that at the maximum power output, 57\% of the follower power is locked to the seed frequency. After the isolator, the system provides 550mW of locked power that could be used for our experiment.