Ultrapure Yellow Laser from Diamond express
The laser based on diamond converts almost half of the pump energy into bright yellow light — an efficiency of 47.7%, a record for such devices. But the main advantage is not the power, but the exceptional purity of the color: the beam is so monochromatic that it can be compared to a musical instrument playing just one note without the slightest wavering.
The light frequency was stabilized using absorption lines of sodium vapor — the very element that gives the familiar orange glow to street lamps. Thanks to this, the instability is squeezed down to 6 hertz: if the laser's frequency were a clock, it would lose less than a second in a million years.
This stability opens the door to telescopes capable of scrutinizing the atmospheres of distant exoplanets, and to quantum computers where every photon must arrive exactly on time.
Original abstract
as written by the authors arXiv:2603.27191
High-power lasers with narrow linewidth 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 output power 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 devices. More importantly, the extreme linewidth-narrowing of Raman lasing in diamond enables a reduction in frequency noise exceeding six 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.
That very same yellow light from street lamps is pushed here to the limit of precision — its frequency stays constant to within billionths.