Patent ID: 7400442

Claim:
An optical signal amplifier, comprising: at least one source of pumping light, said source being configured to produce pumping light having a predominant polarization state; and at least one depolarizer comprising a birefringent optical component having a principal axis oriented at about 45 degrees with respect to said predominant polarization state and coupled to receive said pumping light as an input and having as an output a pumping beam, wherein a Raman gain medium within said optical signal amplifier is configured to receive said pumping beam and optical signals as inputs and to transfer energy from said pumping beam to said optical signals via stimulated Raman scattering, said Raman gain medium is a single mode fiber that is backward pumped, and said at least one depolarizer is configured to provide an output pumping beam that has a degree of polarization in an inclusive range of greater than 1% through 15%.