Interferometric measurements of dispersion-spectra variations in a single-mode fiber

Previous work has demonstrated that group-delay spectra in single-mode fibers can be measured with 0.1-ps resolution by a white-light cross-correlation technique. An application would be to pretest short fibers before drawing an entire preform. This could be particularly useful for achieving high draw yield for fibers whose dispersion spectra are sensitive to core diameter. This paper describes measurements of minimum-dispersion spectra that were obtained using 4-m lengths of fiber that were cut from each end of kilometer-long quadruple-clad, triangular-index, and step-index depressed-clad fibers. The axial uniformity of fiber dispersion was found to be very good. Results show that averaging dispersion spectra using short fiber segments from each end produces excellent agreement when compared with the dispersion spectrum determined from conventional pulse-delay measurements on a long length of fiber.