Coherent proprietary rare earth doping technology is used to fabricate Er/Yb co-doped fibers with industry leading tolerances on the key parameters important for fiber based amplifiers. This ensures the essential lot-to-lot reproducibility required for volume manufacturing of high power CATV and telecom optical amplifiers at 1550 nm. Coherent XP version offers an optimized design for ultra-high efficiency and minimized threshold delivering superior performance. The new ‚¬€œXP fiber is particularly well suited for single-stage amplifiers and lasers requiring high gain factors with limited pump power. Utilizing Coherent proprietary NuCOAT coating technology, these single-mode fibers around 1550 nm offer the best damp and dry heat performance available and ensure extended operating lifetime.