Single-ended PMD measuring technology for metropolitan network

The continuous growth of triple-play services is driving transmission system to higher and higher data rates. Especially in metropolitan areas, Reconfigurable Optical Add-Drop Multiplexers (ROADMs) of 10 Gbit/s and even 40 Gbit/s transmission rates are massively deployed recently. Polarization mode dispersion (PMD) is one of the major obstacles when realizing high bit rate fiber optical systems. Compared to conventional point-to-point test, single-ended test is much more convenient and time-saving to perform. In order to reduce operation expense and capital expense, we extended the capabilities of our existing conventional PMD test sets by reconfiguring them as single-ended PMD test sets. In our single-ended test setup, light received by PMD analyzers is Rayleigh backscattered light and reflected light and it´s quite different from those of conventional test sets. To verify the reliability of test results, we investigated the optical properties of received lights, such as DOP (Degree of Polarization), SOP (State of Polarization) and power level stability. It´s found that test set based on the interferometric method with Amplified Spontaneous Emission (ASE) broadband light source is suitable for our single-ended PMD measurement setup. We have verified the feasibility and accuracy by testing both fiber links with a PMD emulator in the laboratory and installed fibers in the field.