10W single-mode PM optical amplifiers in the 1.5-μm region for space applications

MPB is developing space qualified 10 W End Of Life (EOL) optical amplifiers for longer range applications. Their design employs Polarization Maintaining (PM) Erbium and Erbium-Ytterbium Double Clad Fiber (EDF, EYDF) single-mode fibers. Absorption losses of the EDF and EYDF due to radiation in space are the major challenge to overcome. The gamma radiation tests show that the PM fibers have a greater sensitivity than standard fibers. However, in many applications, PM amplifiers show greater performances which is important for the power consumption. Furthermore, MPB's design minimizes Stimulated Brillouin Scattering in the fibers, a major obstacle to be overcome at this power level, even for on ground applications. Moreover, the compatibility with space environment (vacuum, temperature cycling, and radiation) of the high-power optical and electronic components (isolators, laser-diode pumps, current drivers) has to be demonstrated. The proposed optical designs compensate for radiation-induced losses, without resorting to the use of expensive radiation qualified fibers-a unique method of power recuperation through the photo-bleaching of the active fiber.