Double-pass L-band erbium-doped fiber amplifier with high gain and low noise figure

A two-stage cascaded double-pass structure long- wavelength band (L-band) erbium-doped fiber amplifier (EDFA) is demonstrated. Two 980 nm laser diodes (LDs) are used as forward pumping sources for the two amplification stages. The gain of the L-band EDF A is 35.2-42.5 dB in the wavelength range of 1570–1610 nm, and the noise figure (NF) is 4.11-6.47 dB. In addition, the saturated output power of the L- band EDFA is 14 dBm.