Science & Technology

Nano magnifier converts infrared light to visible light

Impression of a prototype artist who converts infrared light into a visible spectrum using molecules sandwiched between gold particles and a mirror.

Our eyes can’t see infrared, which is why we have infrared detectors that act like extended sensations. However, infrared rays transfer little energy compared to ambient heat, so they are less sensitive and generate a lot of noise. The best infrared detectors overcome this problem by operating at ultra-low temperatures, but this requires a lot of energy and can be very expensive.

An international team of researchers has streamlined infrared detection by developing low-cost devices that guide molecules to convert invisible infrared light into visible light. Molecules absorb mid-infrared light within vibrating chemical bonds and transfer this extra energy to the visible light they encounter. In the process, the infrared is “up-converted” to broadband near the blue edge of the spectrum. This can be seen with the latest cameras.

Converting the frequency of light is not an easy task due to the constraints of the law of conservation of energy. However, researchers have found a workaround by using mediators, or small vibrational molecules, to add energy to the infrared light.

The main challenge is to cross the molecule with visible light fast enough for energy transfer to occur. To that end, a team led by researchers at the University of Cambridge devised a setup that traps the light from the laser in a gap surrounded by a thin layer of gold. A single layer of molecules occupies the same small volume, narrowing light down to one billionth of the space of human hair.

“It was difficult to capture these different colors of light at the same time, but we wanted to find an easy way to make a practical device that wasn’t expensive,” said Cavendish Laboratory co-author. One Dr. Rohit Chikkaraddy said. Experiments based on his simulation of light in these building blocks.

“It’s like listening to a slowly undulating seismic wave colliding with a string of a violin and ringing a high, easy-to-hear whistle without breaking the violin,” said Professor Jeremy Boumberberg, who led the study.

What makes this new infrared detector really useful is that it can be integrated into existing visible light detection technologies such as regular cameras.

Low-cost infrared detectors have a wide range of applications, from pollutant detection and cancer tracking to galactic structure observation. Although this prototype is still in its infancy, researchers are confident that it can further optimize performance and turn it into a cheaper sensor for industrial and scientific applications.

“But so far, the light conversion efficiency of the device is still very low,” warns Dr. Wen Chen, the lead author of the work. “We are currently focusing on improving it further” – an important step towards commercial applications.

The survey results were published in the journal Chemistry..

Nano magnifier converts infrared light to visible light Nano magnifier converts infrared light to visible light

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