Two-stage L-band erbium doped fiber amplifier

Gain enhancement in a long-wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated using isolator to split the erbium-doped fiber (EDF) into two segments. Both segments are pumped separately using a dual forward pumping scheme. Compared to a conventional single- stage amplifier, the small signal gain for a 1580 nm signal can be improved by 5.5 dB without paying much noise figure penalty. The corresponding noise figure penalty was 0.3 dB due to the insertion loss of the optical isolator. The maximum gain improvement of 8.3 dB was obtained at a signal wavelength of 1568 nm while signal and total pump powers were fixed at -30 dBm and 92 mW, respectively.