A compact ultranarrow high-power laser system for experiments with 578 nm ytterbium clock transition

In this paper, we present the realization of a compact, high-power laser system able to excite the ytterbium clock transition at 578 nm. Starting from an external-cavity laser based on a quantum dot chip at 1156 nm with an intra-cavity electro-optic modulator, we were able to obtain up to 60 mW of visible light at 578 nm via frequency doubling. The laser is locked with a 500 kHz bandwidth to an ultra-low-expansion glass cavity stabilized at its zero coefficient of thermal expansion temperature through an original thermal insulation and correction system. This laser allowed the observation of the clock transition in fermionic ¹⁷³Y b with a <50 Hz linewidth over 5 min, limited only by a residual frequency drift of some 0.1 Hz/s.