High-Power Fiber Lasers for Free-Space Optical Communication Uplinks

Ground to satellite optical uplinks are a critical part of the infrastructure in the growing satellite network using free-space optical communications. Because of distortions to the free space optical beam caused by scattering, absorption and turbulence in the atmosphere, the optical power requirements for the uplink are higher than other parts of the system. Fiber lasers are expected to be a key component in the uplink transmitter, due to their robust nature, ability to operate at high average power with excellent beam quality, and high efficiency. This work will provide a brief overview of considerations for optical ground stations, and review of potential fiber laser sources for free space optical communications systems. Detailed results will be presented on a very-large mode area Er-doped fiber amplifier, core pumped by a 1480 nm Raman fiber laser, capable of operating at 100 W average power. Bit error rate testing results for the system at operating powers of up to 90 W will be presented.