From unconventional laser beams to a more robust imaging wave

From University of Rochester:

IMAGE: Creating a more robust terahertz wave from an Airy beam. view more

Credit: (Graphic by Michael Osadciw/University of Rochester)

Here’s the scene: a suspicious package is found in a public place. The police are called in and clear the area. Forced to work from a distance and unable to peer inside, they fear the worst and decide to detonate the package.

New research at the University of Rochester might help authorities in the not-too-distant future be better informed in tackling such situations and do so more safely. Working with a special type of electromagnetic wave–called terahertz (THz)–that’s capable of sensing and/or imaging objects behind barriers, the team demonstrated that they can detect a THz wave at a distance of up to 100 feet. The THz wave created by the researchers is more than five times stronger than what is generated by more conventional means, leading them to believe that a THz wave–and the image of a hidden object–can be detected at much greater distances in the future.

The research project was led by Kang Liu, a PhD student in optics, and Xi-Cheng Zhang, the M. Parker Givens Professor of Optics and the director of the Institute of Optics, in collaboration with a group from Greece led by Tzortzakis Stelios. The results have been published in the journal Optica.

“The use of an unconventional laser beam in our project goes beyond a scientific curiosity,” said Zhang. “It makes possible the remote sensing of chemical, biological, and explosive materials from a standoff distance.”

THz waves, which fall between microwave and the infrared band on the electromagnetic spectrum, can penetrate certain solid objects that are opaque to visible light to create images of what is hidden from view. Unlike traditional x-rays, the waves do so without damaging …

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