L-ShapeDiamond Raman Laser with 35 W at 589nm and Hz-Scale Intrinsic Linewidth

Narrow linewidth lasers with high power and high beam quality in the visible spectrum are essential for emerging quantum and space technologies. Here, we report significant advances in diamond Raman lasers, generating diffraction-limited yellow light at 589 nm with an output power of up to 35 W and enhanced single-frequency stability. The optical-to-optical efficiency from the pump reaches 47.7%, representing a record efficiency for this class of device. More importantly, the extreme linewidth narrowing of Raman lasing in diamond enables a reduction in frequency noise exceeding 6 orders of magnitude, resulting in a measurement-limited intrinsic linewidth of 6 Hz at the maximum power. The laser is further stabilized to the sodium D2a saturation–absorption transition, making it well-suited for sodium-based space and quantum experiments. These results represent a major step toward continuous-wave, high-power, single-frequency laser sources across the visible spectrum that combine ultranarrow linewidth, high efficiency, and near-diffraction-limited beam quality for advanced quantum and space applications.