Scientists have created the sharpest laser in history

A sharper laser means greater accuracy. Scientists have set a new record of laser sharpness when a laser has a linewidth of only 10 milihertz (0.01 hertz).

Spectral line width shows the extent of spectral coverage. We still have not reached the ideal laser, ie only one defined wavelength (photons are transmitted at the same frequency). But we are closer to that goal than ever.

Researchers from the German National Metrology Institute or PTB (Physikasisch Bundesanstalt) said that one of the ways this new laser can prove useful is keeping our time standards.

Physicist Thomas Legero explains: "The smaller the line's laser line width, the more accurate the determination of the atomic frequency in the optical clock. This new laser beam will allow us to significantly improve the quality. clock".

After nearly 10 years of work, the researchers have reached this new record with the help of the Fabry-Pérot silicon resonator . This device is used to control light wavelengths through two fixed mirrors facing each other and inside a double cone.

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

The length of the distance between the mirrors, in particular its stability, controls the laser line width. 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 down to temperatures of -150 degrees Celsius or -238 degrees Fahrenheit.

The world's sharpest laser beam was created like that. The researchers say light waves (of lasers), which fluctuate around 200 trillion times per second, are stable for 11 seconds or longer before they lose sync. That time is enough for the light to go to the Moon and back five times.

If laser is expected to improve radio communication in aerospace, it will have to go further. And PTB is confident that they can bring the line width below 1 milihertz.

Lasers are being used in optical atomic clocks.

Currently, lasers are being used to improve the quality of optical atomic clocks and to measure ultracold atoms with greater accuracy. In the future, lasers can also be used to measure electromagnetic radiation with more precision and even to test relativity.

This study was published in Physical Review Letters.