14 Aug 2014
Contractor Raytheon says that its planar waveguide optics are the key to delivering enough power to down enemy drones.
The US Office of Naval Research (ONR) has awarded Raytheon an $11 million contract to develop a laser weapon with a minimum output power of 25 kW, with the defense firm saying that a demo will be fielded in the “very near future”.
Under the “Ground Based Air Defense (GBAD) Directed Energy On-the-Move Future Naval Capabilities” program, the weapon is expected to be capable of destroying low-flying threats such as enemy drones.
The agreement calls for the field demonstration of a Humvee-mounted, short-range laser weapon system, packaged to meet the US Marine Corps' size, weight and power requirements.
"Raytheon's laser solution generates high power output in a small, light-weight rugged package ideally suited for mobile platforms," said Bill Hart, vice president of Raytheon’s space systems division.
Planar waveguides "key"
The defense contractor explains that its planar waveguide (PWG) optical technology is critical to its particular approach for scaling high-energy lasers by combining beams from a number of sources. “Using a single PWG, the size and shape of a 12 inch ruler, Raytheon high-energy lasers generate sufficient power to effectively engage small aircraft,” claims the firm.
PWG optics were a feature of Raytheon’s earlier work under the Robust Electric Laser Initiative (RELI) Department of Defense program, which also featured Northrop Grumman.
Whereas Northrop used a proprietary beam-combining technique based on diffractive optical elements to ramp the laser output, Raytheon used components with sandwich-type structures featuring a high-refractive-index active core surrounded by lower-index claddings.
Raytheon has previously described the structure as “essentially a one-dimensional fiber in which the thin transverse axis is guided and the wide transverse axis is unguided”.
"Our PWG laser architecture is scalable," Hart said. “We can achieve increasingly higher power levels with the same compact design we're using for GBAD."
He adds that Raytheon is working towards fielding directed energy weapon systems in the “very near future” with a Marine Humvee demonstration.
Whereas 25 kW is deemed to be sufficient to down drones, it is felt that significantly higher laser powers will be required for tougher, faster-moving targets such as rockets and artillery.
Earlier this year, Northrop Grumman won a $25 million contract to develop a 60 kW laser weapon for the US Army.
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