Dual-stage L-band erbium-doped fiber amplifier for gain enhancement

An experiment on gain enhancement in the long-wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated 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 optimum pump power ratio for the first pump was experimentally determined to be 33%. 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.