Abstract: A twin coupler system includes first and second optical couplers that couple a multimode pump fiber into a double-clad active primary fiber. The pump fiber carries multimode pump power from a multimode source. The primary fiber, on the other hand, carries optical information signals on the single mode core that are amplified through the pump power. A system and method for manufacturing the twin coupler system constructs the first coupler by preparing first portions of the primary and pump fibers for coupling and performing fusion and tapering operations on the primary and pump fibers at the first portions, and constructs the second coupler by preparing second portions of the primary and pump fibers for coupling and performing fusion and tapering operations on the primary and pump fibers at the second portions.

Abstract: An optical communication system is described which includes an optical source; an optical modulator, receiving a transmission signal having frequencies included within a signal band and adapted to emit a modulated optical signal of a predetermined optical bandwidth; an optical transmission line comprising an optical fiber portion; and an optical receiver adapted to receive the optical signal in the presence of a predetermined SNR in the signal band, measured in a 5 MHz band. The telecommunication system further comprises, optically connected between the optical modulator and the optical transmission line, a depolarizer comprising two polarization-maintaining optical fiber portions, optically connected with each other in such a manner that the respective polarization axes form an angle of 45.degree.