Cutting through Fog with Laser Focus

Mickael Mounaix and Joel Carpenter have found a new way of controlling how light travels through different materials at different times using optical fibers. (Source: U. Queensland)

Research from the Univer­sity of Queens­land aimed at controlling light in scattering materials, such as fog or biological tissues, will benefit future bio­medical imaging and telecommu­nications. Optics researchers Mickael Mounaix and Joel Carpenter have found a new way of controlling how light travels through different materials at different times using optical fibres.

“The reason you can’t see through a solid brick wall is pretty straight­forward – the wall absorbs the light so no image or information can get through,” Mounaix said. “The reason you can’t see through scattering materials like fog is quite different – most of the light gets through, it’s just completely scrambled and unrecog­nisable.”

Scattering materials like fog, cloud, a glass of milk or biolo­gical tissues have complex micro­scopic structures, and when light travels through these materials, it interacts with them. “Light may enter the cloudy material as a single spot at a single point in time, however as it travels through the material the light gets scattered,” Carpenter said. “On the other side, you end up with light arriving at many different places at many different times.”

Most of the research during the past ten years has focused on controlling the spatial properties of beams of light, but the new research shows how to control light’s properties in time. “For many appli­cations, it’s more important that the light arrives at the desired time, rather than what the light beam looks like as an image,” Carpenter said.

Now, the authors demons­trate how to deliver short optical pulses at very precise times, after propa­gation through an optical fibre. “Such optical fibres were avoided in the past half century because of the scattering they induce, but now that we can adjust these effects, they will play a key role for in-vivo biomedical imaging and telecommu­nications in the near future.” (Source: U. Queensland)

Reference: M. Mounaix & J. Carpenter: Control of the temporal and polarization response of a multimode fiber, Nat. Commun. 10, 5085 (2019); DOI: 10.1038/s41467-019-13059-8

Link: School of Information Technology and Electrical Engineering, University of Queensland, Brisbane, Australia

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