Contrary to popular belief, a laser is not a "beam" of light, but a "strip" that extends across the entire spectrum and has a certain "line width". The priority goal of all research in this area is to reduce this width, and the "ideal laser" will function strictly in one wavelength. But it is still far from it, but an installation with a line width of 10 MHz can already be seen in action.
The linewidth of typical lasers is measured in kHz, but for ultra-precise work, for example, with an atomic clock, smaller sizes are needed. The second measure of the "quality" of a laser is the stability of the frequency of light, since wave oscillations after a certain period of time inevitably begin to oscillate due to synchronization. But the longer this stable state lasts, the better.
The new development of German-American scientists demonstrates outstanding performance in both parameters. So incredible that there is simply nothing to compare this laser with to measure the difference, and therefore the engineers built another one of the same and compare the results of their work. The line width of the new laser is only 10 MHz, and the stability reaches 11 seconds, which means that the beam can travel 3.3 million km, ten times more than from the Earth to the Moon, without any deviations and errors.
The laser is based on a Fabry-Perot silicon resonator with two opposite mirrors. The structure is 21 cm long and is not subject to vibration, temperature changes or pressure. Not ideal, but as close to them as possible conditions for making the most accurate measurements. Scientists are now looking for ways to lower the temperature in the cavity even further and are experimenting with the composition of the mirror material to achieve a phenomenal 1 MHz line width.