DARPA-funded researchers develop hollow-core fiber for use in sensors

Researchers funded by the Defense Advanced Research Projects Agency recently developed a hollow-core fiber that significantly improves the performance of high-power military sensors, DARPA announced on Wednesday.

Scientists with DARPA's Compact Ultra-Stable Gyro for Absolute Reference developed an advanced version of the hollow-core fiber technology and brought design and production capacity inside the U.S. The fiber uses a hollow, air-filled core to remove the fundamental limitations of glass optical fiber and improves performance by forcing light to go through channels of air, instead of the glass around it.

The spider-web-like core fiber can be used for advanced military applications, such as in high-precision fiber optic gyroscopes for inertial navigation.

Hollow-core fiber can be coiled and bent while guiding light at speeds 30 percent faster than standard fiber.

"Previous instantiations of hollow-core fiber have shown these high propagation speeds, but they weren't able to do so in combination with the properties that make it useful for military applications," Josh Conway, DARPA's program manager, said. "The real breakthrough with COUGAR fiber is that it can achieve a single-spatial-mode, maintain polarization and provide low loss, all while keeping more than 99 percent of the optical beam in the air."

DARPA started COUGAR in an effort to improve fiber optic performance for military-grade gyroscopes to develop world-class, hollow-core production capacity in the U.S.

"While we are still working on integrating this new technology into a gyroscope, the fiber itself is revolutionary," Conway said. "This type of technology may also lend itself to other types of high-power sensors and additional applications where intense optical beams are required. Hollow-core fiber is also naturally radiation hardened, so it may open up fiber applications to space systems."