Simple four-wave-mixing-based method for measuring the ratio between the third- and fourth-order dispersion in optical fibers

A simple four-wave-mixing (FWM)-based method for measuring the ratio between the third- and the fourth-order dispersion coefficients (β3/β4) in optical fibers is reported. The FWM interaction involves a low power laser and a low power amplified spontaneous emission noise source. The method is applied in several dispersion-shifted and non-zero-dispersion-shifted fibers with lengths varying from 0.03 to 25km, and we have obtained an error of less than 3% in measuring β3/β4. In highly nonlinear fibers the error has presented a strong dependency with longitudinal variations of the zero-dispersion wavelength (λ0); an error less than 20% could be obtained in most of the tested fibers. Our method also allows for a fast estimation of the distribution of fluctuations of λ0 along the fiber.