Ultra-efficient erbium-doped fiber amplifier

Abstract
The gain and saturation characteristics of 0.98 μm and 1.48 μm pumping are investigated for an erbium‐doped fiber amplifier with a mode field diameter of 4.8 μm, and a relative refractive index difference of 1.67%. Gain coefficients of 10.2 dB/mW at 0.98 μm pumping and 5.1 dB/mW at 1.48 μm pumping are obtained. The saturation output power is +12 dBm with a launched pump power of 50 mW for 1.48 μm pumping. The energy conversion efficiency at 1.48 μm pumping reaches as high as 71%.