Laser Beam Steering Made More Efficient

The ability to precisely control the direction of a laser beam in an energy-efficient and inexpensive way has been discovered by researchers from North Carolina State University.

"In many cases, it is much easier to redirect a laser beam at a target than to steer the laser itself. We intended to develop a way to do this efficiently and without moving anything," said Dr. Michael Escuti, an associate professor of electrical engineering at NC State and co-author of a paper on the research. "We also wanted to be able to steer the beams over a wide range of angles, which is important for practical applications."

The key to the researchers' success was the use of "polarization gratings," which consist of a thin layer of liquid crystal material on a glass plate. They created a device that allows a laser beam to pass through a stack of these polarization gratings, then manipulated the optical properties of each grating, enabling them to steer the laser beams by controlling how each individual grating redirects the light.

"Because each individual grating is very good at redirecting light in the desired directions with almost no absorption, the stack of gratings [does] not significantly weaken the laser power," Escuti said.

Another advantage of the system, Escuti explained, is that "every grating that we add to the stack increases the number of steerable angles exponentially. So, not only can we steer lasers efficiently, but we can do it with fewer components in a more compact system.

"Compared to other laser steering technologies, this is extremely cost-effective. We're taking advantage of materials and techniques that are already in widespread use in the liquid crystal display sector."

The technology has a variety of potential applications. For example, free space communication uses lasers to transfer data between platforms – such as between satellites or between an aircraft and soldiers on the battlefield. This sort of communication relies on accurate and efficient laser beam steering. Other technologies that could make use of the research include laser weapons and lidar, which uses light for optical scanning applications, such as mapping terrain.

Escuti's team has delivered prototypes of the technology to the US Air Force and currently is engaged in additional research projects to determine the technology's viability for a number of other applications.

For more information, visit: www.ncsu.edu