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 thatovercomes the effects of polarization gain anisotropy inrare-earth doped optical fiber amplifiers. An optical fiberhas at least one rare-earth doped fiber portion foramplifying a light signal. Light signals are passed throughthe doped fiber portion in a first incident polarized state.This light signal is reflected back from a Faraday effectmirror and through the doped fiber portion in its orthogonalpolarized state so as to overcome the effects ofpolarization gain anisotropy. The rare-earth dopedamplifier is preferably an erbium-doped fiber amplifier. Asignal is initially passed through one part of a Faradayoptical circulator and out a second port into the dopedamplifier. On its return pass, the light signal enters thesecond port and then exits a third port. The opticalamplifier can include a wavelength division multiplexorcoupler for merging the pump signal with the original lightsignal. Various amplifier configurations are also disclosedwhich are either co-propagating or counter-propagating andreflect only the signal, reflect only the pump signal, orreflect both the pump signal and original light signal.