Patent ID: 7848014

Claim:
An apparatus comprising: a first optical combiner that is configured to receive an input optical signal to be amplified and a pump light beam, wherein the first optical combiner is configured to combine for output the input optical signal and the pump light beam; a first cladding pumped optical fiber having a first end and a second end, the first end configured to couple to the output of the first optical combiner, wherein the only optically active dopant in the first cladding pumped optical fiber is Erbium only and the first cladding pumped optical fiber outputs at the second end a first amplified optical signal together with power of the pump light beam not absorbed by the first cladding pumped optical fiber; and a second cladding pumped optical fiber having a first end and a second end, the first end configured to be coupled to the second end of the first cladding pumped optical fiber, wherein Erbium and Ytterbium are the optically active dopants in the second cladding pumped optical fiber and the second cladding pumped optical fiber absorbs power of the pump light beam not absorbed by the first cladding pumped optical fiber to further amplify the first amplified signal and produce an output amplified optical signal that is a desired amplified version of the input optical signal.