Patent ID: 7346280

Claim:
Apparatus for amplification in a bi-directional optical communication link, said apparatus comprising: a first Erbium-doped fiber amplifier that amplifies a first WDM signal that occupies a first subband and propagates through said bi-directional optical communication link; a Raman pump module that injects pump energy into a first span of said bi-directional optical communication link to induce Raman amplification of a second WDM signal that occupies a second subband that propagates through said bi-directional communication link in a direction opposite a direction of propagation of said first WDM signal; a second Erbium-doped fiber amplifier that amplifies said second WDM signal; a first circulator having a first port coupled to said first span and a second port coupled to an input of said second Erbium-doped fiber amplifier wherein a third port of said first circulator is coupled to said Raman pump module; and a fiber Bragg grating coupled to a fourth port of said first circulator such that an output of said first Erbium-doped fiber amplifier is coupled to said fourth port through said fiber Bragg grating and said pump energy enters said third port, exits said fourth port, reflects from said fiber Bragg grating, and exits said first port to enter said first span.