Four years ago the Airborne Laser Test Bed, a modified 747 that shoots lethal photons, destroyed a ballistic missile in flight by blasting it with a chemical laser. But after its test demonstration, the Pentagon mothballed the plane because of its annual R1 billion-plus price tag.
Still, the dream of flying laser weapons won’t rest in the boneyard if DARPA has anything to do with it. The agency is researching fibre-optic lasers as an alternative to massive chemical lasers. Lockheed Martin and Northrop Grumman were awarded contracts to build a prototype for a classified programme called Endurance. Instead of blowing up a missile, this system will target optically guided missiles. The programme can take advantage of lightweight lasers on drones because it takes less power to scorch optics than to melt a rocket casing. This technology could protect combat aircraft or counter terrorist threats to commercial airlines.
Fibre lasers have near-perfect beam quality, which is a measure of how much energy can be focused in one area. Endurance will combine dozens of fibre-laser beams into one with superb beam quality.
The telecoms boom of the ’90s accelerated fibre-optic tech. When the industry went bust in 2001, fibre companies found a new market: high-power fibre lasers for manufacturing. That means they’re designed to be reliable.
The material of most high-power fibre lasers has a high quantum efficiency; the wavelength of light energising the laser is close to that of the laser’s output colour. Fewer photons are wasted, and the system weighs less.
– Olivia Koski