THEORY OF NONDEGENERATE 4-WAVE-MIXING IN A BIREFRINGENT OPTICAL-FIBER

Nondegenerate four-wave mixing in a birefringent optical fibre pumped with two waves of orthogonal linear polarisations at different wavelen gths is studied theoretically. It is shown that, under appropriate con ditions, the frequency shift in the four-wave mixing process is propor tional to the polarisation-mode dispersion in the fibre, and insensiti ve to the difference between the two pump wavelengths. The theory expl ains the recent experimental observation that a laser beam can mix wit h a spectrum of light in a birefringent fibre to generate a distinct f requency-shifted beam. (C) 1998 Elsevier Science B.V. All rights reser ved.