Polarization mode dispersion measurements on long buried cables

This paper describes the polarization mode dispersion (PMD) measurements of long standard fibers, dispersion-shifted (DS-) and dispersion-flattened (DF-) fibers uncabled on bobbins and in cables installed in the test links Berlin IV (18 km long) and Berlin VI (22.6 km). The PMD is measured with the aid of the interferometric technique, using a Michelson-interferometer. This method is not restricted to long fibers with low birefringence, it can be used to measuring the PMD and group beatlength of short high-birefringent fibers with a high accuracy. It will be shown that the cabling procedure increases the PMD values considerably, up to one order of magnitude.