10 W-level monolithic continuous-wave yellow laser at 589 nm

In this Letter, a direct-diode-pumped monolithic yellow laser at 589 nm was realized in the Yb³⁺-doped YCa₄O(BO₃)₃ (Yb:YCOB) crystal. This intriguing yellow light emission originates from the collaborative phonon-coupling and self-frequency doubling effect, which enables a simple laser setup and excellent power scaling capacity. Via an effective direct-cooling scheme, the thermal accumulation on the Yb:YCOB gain medium was alleviated, thus yielding high-power laser loading and stable conversion efficiency. As a result, the continuous-wave laser power at 589 nm was improved to 10.2 W with a high optical-to-optical conversion efficiency of 24.3%. This work presents the first, to the best of our knowledge, ten-watt-level microchip yellow laser, in which the output power is ten times higher than that of diode-pumped Dy 3+ - and Tb 3+ -doped lasers.