Multi-frequency telecom fibered laser system for potassium laser cooling

We describe a compact and versatile multi-frequency laser system for laser-cooling potassium atoms, by frequency doubling a fiber-optic telecom beam (\(\simeq 1534\) or \(1540\)~nm). Low-power fiber-based telecom lasers and components generate a single beam containing the cooling and repumper half frequencies, subsequently amplified by high-power amplifier. A final free-space SHG stage generates a single beam with typically 2.5 W at quasi-resonant frequencies (\(\simeq 767\) or \(770\)~nm) with high-quality mode and ready for laser cooling. This allowed to trap up to \(4\times10^9\) \(^{41}\)K atoms with fast loading times (2.5 s) at sub-Doppler temperatures of 16~\(\mu\)K. This opens promising perspectives towards versatile and transportable ultracold atom setups.