Special photodetectors could also be used to see through snow to find avalanche victims or vehicles caught in a snowstorm, says a researcher from Polytechnique Montreal.

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Self-driving vehicles that “see” through snow and fog, cameras that can identify stale fruits and vegetables, and better detectors for toxic gases are some of the potential applications for a technology being worked on by researchers from Polytechnic Montreal.

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Professor Oussama Moutanabbir’s team is developing a photodetector based on custom-made semiconductors on silicon chips, a kind of “bionic eye” sensitive to a specific infrared band that the human eye cannot detect.

“These are not thermal cameras, they are cameras that detect the light that exists,” Moutanabbir explained. “If we go out and it’s dark, it’s only dark because we don’t have the right detectors. Our eyes are optimized to detect the visible.

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While infrared cameras are already available on the market, Moutanabbir’s team is specifically interested in the region of the spectrum with a wavelength between 1.7 and 8 micrometers, known as infrared bands at short and medium waves.

The new camera can detect silhouettes or see writing on an object, which is a “very significant advantage” over thermal cameras, Moutanabbir said.

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Rather than detecting heat, he said, the detector can see light reflected from an object when illuminated by light at those wavelengths. It works the same way as a human eye or a conventional camera, but using a different type of light.

Targeting the short and mid-wavelength infrared bands will allow the photodetector to solve the problem of visible light being reflected from snow, ice and fog. These infrared bands are not reflected as much, so detectors in these bands can “see” through these obstacles.

Along with adding cameras to vehicles to improve safety, the technology could also see through snow to find avalanche victims or vehicles caught in a blizzard, Moutanabbir said.

The professor’s team has been working on this technology for several years, with the support of the Innovation for Defence, Excellence and Security funding program of the Department of National Defence, the Canadian Foundation for Innovation and PRIMA Quebec.

Semiconductors are made at Polytechnique Montreal by placing germanium and tin atoms on silicon wafers, layer by layer, creating “crystals that don’t exist in nature,” Moutanabbir said.

The group recently showed that its photoreceptors are efficient at room temperature and that their response time is fast enough for spectroscopic photodetection applications. Its advances were recently the subject of articles in the scientific journal ACS Photonics.