Patent ID: 6972898

Claim:
A wide band optical fiber amplifier used in an optical transmission system, comprising: a first amplifying unit configured for amplifying an optical signal having C and L-band optical signal components; a distributor coupled to said first amplifying unit configured for receiving the amplified C and L-band optical signal components via a first path; a gain flattening filter coupled to said distributor for receiving said amplified C and L band optical signal components and for gain flattening only said amplified C band optical signal component; a first reflector coupled to said gain flattening filter for reflecting said amplified gain flattened C band optical signal component and said amplified L band optical signal component back into said distributor, via said gain flattening filter, said first reflector causing said gain flattened optical signal component to be gain flattened a second time; a second amplifying unit coupled to said distributor for receiving and amplifying the twice gain flattened amplified C band optical signal component and said amplified L-band optical signal component; the distributor further configured for receiving said amplified C and L band optical signal components from the second amplifying unit and for splitting the amplified C and L band optical signal components into a separate amplified C and L band optical signal components; a third amplifying unit coupled to said distributor and configured for amplifying the separate amplified L-band optical signal component; a second reflector coupled to said third amplifying unit configured for reflecting the separate amplified L band optical signal component back to said distributor via said second amplifying unit; and the distributor further configured for combining the reflected separate amplified L band optical signal component from the third amplifying unit and passing back through the second amplifying unit with the separate amplified C band optical signal component from the second amplifying unit and for outputting the combined signal.