Scientists have created the sharpest laser in history.

Sharper lasers mean greater precision. Scientists have set a new record for laser sharpness by creating a laser with a linewidth of just 10 millihertz (0.01 hertz).

The linewidth represents the extent to which the spectrum is covered. We are not yet at the ideal laser, which is a laser with only one wavelength (photons transmitted at the same frequency). But we are closer than ever.

Researchers from the German National Metrology Institute or PTB (Physikasisch Bundesanstalt) say one way this new laser could prove useful is in keeping our time standards.

"The smaller the linewidth of the laser, the more precise the determination of the atomic frequency in an optical clock. This new laser will allow us to significantly improve the quality of the clock," explains physicist Thomas Legero.

After nearly 10 years of work, the researchers achieved this new record with the help of a Fabry-Pérot silicon resonator. This device is used to control the wavelength of light via two fixed mirrors placed opposite each other and located inside a double cone.

Silicon resonator, responsible for creating the sharpest laser beam to date.

The length of the gap between the mirrors, and in particular their stability, controls the laser's linewidth. So the challenge for scientists is to keep these mirrors as stable as possible. That means eliminating interference from pressure changes, vibrations from sound waves, seismic waves, and temperature fluctuations.

The final task is to minimize the thermal motion of atoms (Brownian motion) that occurs in all materials at finite temperatures. To do this, the resonator is made from single-crystal silicon and cooled to -150 degrees Celsius, or -238 degrees Fahrenheit.

The world's sharpest laser was created this way. Researchers say the light waves, which oscillate about 200 trillion times per second, are stable for 11 seconds or so before they lose sync. That's enough time for the light to travel to the moon and back five times.

If lasers are expected to improve radio communications in space, they will have to go much further. And PTB is confident that they can get the linewidth down to less than 1 millihertz.

Lasers are being used in optical atomic clocks.

Lasers are currently being used to improve the quality of optical atomic clocks and to measure ultracold atoms with greater precision. In the future, lasers may also be used to measure electromagnetic radiation with greater precision and even to test the theory of relativity.

The study was published in Physical Review Letters.

According to Khoahoc.tv