PHASE-MATCHING FOR PARAMETRIC AMPLIFICATION IN A SINGLE-MODE BIREFRINGENT FIBER - INFLUENCE OF THE NON-PHASE-MATCHED WAVES

In a single-mode birefringent fiber, phase matching in four-photon par ametric amplification implies linear terms, which are due to dispersio n and birefringence, and nonlinear terms, which are due to self- and c ross-phase modulations. In the normal-dispersion regime combinations o f these terms lead to three phase-matched regimes. When the pump is eq ually divided between the two polarizations one must take the nonphase -matched waves into account to obtain accurate values of the phase-mat ched wavelengths and of the gain. To calculate these parameters we ana lytically develop corrected models of both the four-wave mixing formal ism and of the modulation instability formalism and show the correspon dence between these two approaches. Then we experimentally show that t he parametric gain increases with the value of the birefringence. (C) 1997 Optical Society of America.