Nondestructive position-resolved measurement of the zero-dispersion wavelength in an optical fiber

We describe a new technique for mapping the distribution of the zero-dispersion wavelength in a span of optical fiber. With this technique, which is based on four-wave mixing of short pulses, we obtained a spectral accuracy of /spl plusmn/0.2 nm and a spatial resolution of 700 m. Theoretical analysis agrees well with experimental results and points to an order of magnitude improvement in spatial resolution using shorter pulses. Spatial resolutions less than 100 m may be necessary because we find, by destructive measurements, variations in lambda-zero by as much as 0.5 nm over spans of 500 m.