Space qualified EDFA uses radiation-harden version erbium-doped or erbium/ytterbium co-doped specialty fibers as gain medium. Al the other passive fiber optic components are either High-Rel category items or the best-in-class high power level fiber optics.
Sub-Sea
The key sections of Sub-Sea EDFAs, such as the micro-controller and the pump lasers, have built-in redundancy in design. This allows the controlling electronics to be with high reliability, which features an FIT value below 20