High Powered Er:Yb Doped Fiber Laser Amplifier

Aspen Systems proposes to develop a Er+3:Yb+3 doped double clad fiber laser amplifier with an output power of 10 W. The active core enclosed by a large rectangular inner cladding is end pumped with a beam from a laser diode array delivered by a bundle of rectangular core fibers preserving the brightness. This active fiber is periodically re-charged, using efficient side couplers, with a system of powerful laser diodes pigtailed to the rectangular core fibers.A new revolutionary technology of laser diode self-correction that includes enhancing the power, correcting the astigmatism, and collimating the beam results in efficient laser to fiber coupling. Moreover, a fiber polishing technique will be used for shaping the fiber end face to match the numerical aperture of the laser beam with an efficiency of 93 - 95%. The side couplers will provide coupling efficiency better than 95%.In Phase I, the concept will be demonstrated analytically and experimentally. The technologies that will be developed and fabricated are enhancing the laser beam power and quality, polishing technique to shape the fiber end face, and efficient side coupling scheme. The complete fiber laser system will be assembled and tested during the Phase II with the final product delivered to the USAF.