Patent ID: 7173756

Claim:
An optical amplifier for variable length optical fiber spans, the optical amplifier comprising: a) at least one discrete optical amplifier that is coupled into an optical fiber span that has a predetermined optical loss that is greater than or equal to 35 dB; b) a distributed optical amplifier that is coupled in the optical fiber span, a combined spectral gain of the at least one discrete optical amplifier and the distributed optical amplifier compensating for substantially all losses experienced by optical signals propagating in the optical fiber span, a gain of at least one of the at least one discrete optical amplifier and the distributed optical amplifier being adjusted to cause an increase in an associated effective noise figure that is less than 8 dB when the gain is reduce by 8 dB; and c) an optical loss element that is coupled into the optical fiber span, the optical loss element introducing an optical loss into the optical fiber span that achieves a desired combined gain dynamic range and associated effective noise figure for the predetermined optical loss of the optical fiber span.