The reflectivity is as high as 99.99923%, and the first super mirror is available in the mid-infrared wave range.

CTOnews.com, December 9 (Xinhua)-- an international scientific team of experts from the United States, Austria and Switzerland recently successfully produced the first mid-infrared wavelength super mirror with a reflectivity of 99.99923%.

Mirrors have a wide range of uses, such as being equipped in sensors to accurately sense environmental optical changes; in manufacturing, for laser cutting and welding, higher reflectivity can bring more precise effects.

In the wavelength range of visible light (that is, between 380 nm and 700 nm), the reflectivity of the metal mirror is up to 99%, which means that one photon is lost for every 99 photons reflected.

In the near infrared range (between 780nm and 2.5um), the reflectivity of the mirror coating is 99.9997%, and only 3 photons are lost out of 1 million reflected photons.

In the past, scientists have been trying to extend the performance level of this super mirror to the mid-infrared (wavelengths from 2.5 μ m to 10 μ m or higher), but the reflectivity of the best mid-infrared mirror is 99.99%. The photon loss rate is 33 times that of the near-infrared supermirror.

The international research team developed a new coating process by combining traditional thin film coating technology with new semiconductor materials.

A silicon substrate with a diameter of 25 mm for super mirrors. They first developed a 25 mm diameter silicon substrate, then let the high reflection semiconductor crystal structure grow on a 10 cm gallium arsenide chip, then divided it into smaller circular mirrors, and then installed these mirrors on the silicon substrate. finally, the reflectivity reached 99.99923%.

CTOnews.com attached the reference address of the paper: Truong, GW., Perner, L.W., Bailey, D.M. Et al. Mid-infrared supermirrors with finesse exceeding 400 000. Nat Commun 14, 7846 (2023). Https://doi.org/10.1038/s41467-023-43367-z