Four-wave mixing in optical fibers and its applications

Four-wave mixing (FWM) is a phenomenon that must be avoided in DWDM transmission, but depending on the application it is the basis of important second-generation optical devices and optical device measurement technology. This paper discusses the theory of FWM, and then introduces one of its applications - a broadband all-optical simultaneous wavelength converter developed using a high nonlinearity dispersion fiber (HNL-DSF) that efficiently produces FWM. The conversion bandwidth extends to 23.3 nm HWHM (half width at half maximum), the widest yet reported for wavelength conversion using non-polarization-maintaining fiber. As a further application, a novel technique is introduced for measuring the nonlinear coefficient of optical fibers by evaluating FWM generating efficiency. With this technique it is now possible to effect simultaneous measurement of the chromatic dispersion and nonlinear coefficient of fiber.