Polarization-insensitive optical spectral inversion using four-wave mixing in a dispersion-shifted fiber

A theoretical analysis of spectral inversion using a nondegenerate four-wave mixing wave in a dispersion-shifted fiber with two orthogonally polarized pumps is given. The configuration using two orthogonally polarized pumps was considered as polarization-insensitive spectral inversion. Our analysis will show that the spectral inversion still presents a polarization dependence up to several dB even when polarization-mode dispersion of conversion fiber is ignored. The polarization dependence is mainly induced by two factors: asymmetrical pump depletion and polarization-sensitive crosstalk four-wave mixing waves. The chirp characteristics of spectral-inverted signal are also given. The chirp may present a polarization dependence, depending on input signal power. (C) 1998 Academic Press.