Optical fiber system and method for overcoming the effects of polarization gain anisotropy in a fiber amplifier

摘要

An optical fiber system and method is disclosed that overcomes the effects of polarization gain anisotropy in rare-earth doped optical fiber amplifiers. An optical fiber has at least one rare-earth doped fiber portion for amplifying a light signal. Light signals are passed through the doped fiber portion in a first incident polarized state. This light signal is reflected back from a Faraday effect mirror and through the doped fiber portion in its orthogonal polarized state so as to overcome the effects of polarization gain anisotropy. The rare-earth doped amplifier is preferably an erbium-doped fiber amplifier. A signal is initially passed through one part of a Faraday optical circulator and out a second port into the doped amplifier. On its return pass, the light signal enters the second port and then exits a third port. The optical amplifier can include a wavelength division multiplexor coupler for merging the pump signal with the original light signal. Various amplifier configurations are also disclosed which are either co-propagating or counter-propagating and reflect only the signal, reflect only the pump signal, or reflect both the pump signal and original light signal.