Patent ID: 6603594
Filing Date: 2003-08-05
Classification: H01S,H04B

Abstract:
A multi-stage optical amplifier, comprising:one or more optical fibers including at least a distributed Raman amplifier fiber and a discrete Raman amplifier fiber, the one or more optical fibers configured to communicate with one or more signal sources producing a plurality of signal wavelengths &lgr;s and at least two pump sources that produce one or more pump beam wavelengths &lgr;p, the distributed Raman amplifier fiber is configured to introduce an effective optical noise figure to at least a portion of the plurality of signal wavelengths &lgr;s of less than 8 dB and less than an effective optical noise figure introduced by the discrete Raman amplifier fiber, wherein at least one of the one or more pump beam wavelengths &lgr;p is shorter than at least a portion of the plurality of signal wavelengths &lgr;s, and wherein the discrete Raman amplifier fiber is capable of introducing a gain level to at least some of the plurality of wavelengths &lgr;s of at least 5 dB; a signal input port coupled to the one or more optical fibers; a signal output port coupled to the one or more optical fibers; a first pump input port, the distributed Raman amplifier fiber being positioned between the signal input port and the first pump input port and the discrete Raman amplifier fiber being positioned between the first pump input port and signal output port; a second pump input port coupled to the one or more optical fibers and positioned between the first pump input port and the signal output port; and wherein the plurality of signal wavelengths &lgr;s flow in a first direction and the one or more pump beam wavelengths &lgr;p flow in a direction counter to the first direction, and wherein at least one of the distributed Raman amplifier and the discrete Raman amplifier comprises a dispersion compensating fiber.