Patent ID: 7440171

Claim:
An optical amplifier, comprising: a first doped fiber portion, wherein an optical signal transmitted through the first doped fiber portion is amplified with a first gain per unit length and wherein the first doped fiber portion has first control values selected to generate a first set of output characteristics; a second doped fiber portion coupled to the first doped fiber portion to receive the optical signal from the first doped fiber portion, wherein the optical signal is amplified by the second doped fiber portion with a second gain per unit length that is higher than the first gain per unit length of the first doped fiber portion, wherein the second doped fiber portion has second control values that are selected to produce a second set of output characteristics based on the second control values and the first set of output characteristics; and a third doped fiber portion coupled to the second doped fiber portion to receive the optical signal from the second doped fiber portion, wherein the third doped fiber portion has a higher saturation power than either of the first doped fiber portion and the second doped fiber portion, the third doped fiber portion having a third gain per unit length, wherein the third doped fiber portion has third control values and produces a third set of output characteristics based on the third control values and the second set of output characteristics; and wherein: the first, second and third control values each include one or more of a dopant concentration, a doped fiber length, a pump power, or a transmission signal power; and the first, second, and third set of output characteristics each include one or more of a transmission signal gain, a noise figure, a saturation power, or an attenuation of pump energy.