Detecting Explosives and Guiding High Power Microwaves with Curved Laser Beams

  • Published
  • By Maria Callier
  • Air Force Office of Scientific Research
ARLINGTON, Va. --  Research into creating curved laser beams in space may make it possible to someday accelerate charged particles and guide high power microwaves and radiofrequency waves in the air, all of which will be powerful tools for the Air Force in detecting explosives and chemical/biological agents at remote locations.

With funding from the Air Force Office of Scientific Research, investigation of this technology is underway at the University of Arizona's College of Optical Sciences and the Arizona Center for Mathematical Sciences under the guidance of Drs. Pavel Polynkin and Jerry Moloney.

In a recent issue of Science, Moloney who conducted the research in collaboration with Professor Demetrios Christodoulides and co-workers from the University of Central Florida, explained the process of the laser beams bending: 'they are made up of a combination of waves, one leading one, which carries most of the beam's intensity, and many smaller trailing waves. These waves interfere with each other so that the leading wave curves one way while the tail bends in the opposite direction.'

When powerful laser pulses reach sufficient intensity, they form filaments or peculiar self-guiding beams of light. In order to be useful, these filaments' location and shape must be controlled. Some laser beams (termed Bessel beams) produce longer, plasma channels while self-bending Airy beams generate curved light filaments and plasma channels in the air.

"An important practical aspect of Airy Beams is their self-healing property. They can quickly re-assemble themselves, after they are blocked or distorted. This allows for distortion-free propagation of these beams through turbulence and foggy environments," said Polynkin.

The main challenges for the physicists now are to invent innovative means to extend the light filaments and plasma channels over distances, in order to make these effects useful in real-life remote applications. The scientists plan to further investigate the physics underlying the creation of light filaments and plasma channels in environments where they can duplicate varying atmospheric conditions.

"We will collaborate with scientists at the 711th Human Performance Wing at Wright-Patterson Air Force Base in Ohio to gain a more complete understanding of multiple light filaments and plasma channels in the atmosphere," said Moloney.

"In the future, we plan to conduct experiments in a controlled environment that mimics different atmospheric conditions, including turbulence and high pressure," said Polynkin.

Despite the progress that has already been made, the practical use of laser filaments may be years away because the pulse shape is not predictable and that makes control, which is much needed, impossible.

Polynkin cautioned, "As a result, accurate comparison with theory and modeling will not be possible and the researchers will not learn a lot from such experiments."