A multi-stage optical amplifier includes at least a distributed Raman amplifier
fiber and a discrete amplifier fiber. The amplifier is configured to be coupled
to at least one signal source that produces a plurality of signal wavelengths s;
and at least a first pump source that produces one or more pump beam wavelengths
p. A signal input port is coupled to the amplifier. A signal
output port is coupled to the amplifier. The distributed Raman and discrete amplifier
fibers are positioned between the signal input port and the signal output port.
A first pump input port is coupled to a first end of the distributed Raman amplifier
fiber. A second pump input port is coupled to a second end of the distributed Raman
amplifier fiber. The first end is located closer to the signal input port than
the second end. A third pump input port is coupled to the discrete amplifier fiber.
