Global defense and technology corporation Northrop Grumman Corporation (Redondo Beach, CA) has been chosen to develop single-frequency fiber amplifiers for the new Revolution in Fiber Lasers (RIFL) program by the Defense Advanced Research Projects Agency (DARPA).
The RIFL program takes an approach to maturing fiber-laser technology similar to one Northrop Grumman demonstrated for solid-state lasers through support from U.S. military services and government agencies--by designing the building blocks needed to combine laser beams that can be scaled to a weapons-class power level while maintaining good beam quality. The ultimate goal of the RIFL program is to form a single, very-high-power (> 3 kW), narrowline, fiber-laser amplifier in the far field operating near the 1 μm (ytterbium) wavelength, with an overall electrical efficiency of ≥ 30% and a beam quality factor of less than 1.4x diffraction-limited.
Fiber lasers are 1.5 to 2 times more efficient than solid-state lasers, delivering more laser power per weight and volume. High beam quality and efficiency make fiber laser technology intrinsically ideal to pursue in parallel with solid-state lasers, the company noted.
"We'll build on internal successes, demonstrating the ability to scale and operate single-frequency fibers at high powers," said Dan Wildt, vice president of Directed Energy Systems for Northrop Grumman's Space Technology sector. "Coupled with the proprietary scalable architecture that we've successfully developed for the Joint High Power Solid State Laser program, we have demonstrated the essential building blocks for success. RIFL will enable us to scale this important technology to weapons-class powers."
Northrop Grumman has previously scaled narrowband fiber lasers to powers of 400 W by combining multiple fiber amplifiers with a near-perfect beam quality of 1.1. Northrop Grumman received a $4.5 million, 15-month contract for Phase I, with an option for a $4.6 million, 18-month Phase II contract. Key goals of the DARPA contract are demonstration of single-frequency fiber amplifiers at 1kW in the 15-month first phase and 3 kW at the end of the 18-month second phase.
Single-frequency fiber lasers and amplifiers are now typically limited to several hundred watts by an effect known as Stimulated Brillouin Scattering (SBS), which reflects power backwards and damages low-power components. The Northrop Grumman-led team will use proven proprietary approaches to eliminate SBS and achieve the program's goals.
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