The present invention discloses a long-band Erbium doped-fiber amplifier including:
a first Erbium doped fiber with a predetermined length, coupled to a first pumping
light source through a first wavelength-selective coupler, for amplifying a C-band
optical signal by supplied pumping light; a second Erbium doped fiber with a predetermined
length for amplifying an L-band optical signal by a second pumping light source;
a feedback loop for recycling a specific C-band wavelength generated in the amplification
of the first Erbium doped fiber as the second pumping light source of the L-band
optical signal; a tap coupler formed between the first and second Erbium doped
fibers, for dividing the optical power amplified in the first Erbium doped fiber,
for supplying a predetermined ratio of optical power to the second Erbium doped
fiber, and for re-inputting the residual optical power to the feedback loop; and,
a second wavelength-selective coupler for coupling the signal light transmitted
from the tap coupler to the first Erbium doped fiber.