An ultraviolet diode laser system for laser cooling trapped ytterbium ions

We describe the design and performance of an ultraviolet diode laser system for laser cooling trapped ytterbium ions without frequency doubling. The performance is similar to resonantly doubled laser systems, but with greater efficiency, reduced size, expense and fragility. The system achieved laser cooling of ytterbium ions in a linear Paul trap to less than 270 mK. No shorter wavelength laser has previously been used for laser cooling