Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new technique to squeeze infrared light into ultra-confined spaces, generating an intense, nanoscale antenna that could be used to detect single biomolecules.
The researchers harnessed the power of polaritons, particles that blur the distinction between light and matter. This ultra-confined light can be used to detect very small amounts of matter close to the polaritons. For example, many hazardous substances, such as formaldehyde, have an infrared signature that can be magnified by these antennas. The shape and size of the polaritons can also be tuned, paving the way to smart infrared detectors and biosensors.
The research is published in Science Advances (“Ultra-confined mid-infrared resonant phonon polaritons in van der Waals nanostructures”).
“This work opens up a new frontier in nanophotonics,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering, and senior author of the study. “By coupling light to atomic vibrations, we have concentrated light into nanodevices much smaller than its wavelength, giving us a new tool to detect and manipulate molecules.”
Polaritons are hybrid quantum mechanical particles, made up of a photon strongly coupled to vibrating atoms in a two-dimensional crystal.
“Our goal was to harness this strong interaction between light and matter and engineer polaritons to focus light in very small spaces,” said Michele Tamagnone, postdoctoral fellow in Applied Physics at SEAS and co-first author of the paper.
Read more at nanowerk.com

Image Credit:  Harvard SEAS

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