Definition, meaning, and measurement of the polarization extinction ratio of fiber-based devices

We clarify the definition of the polarization extinction ratio--also called polarization cross talk--of fiber-based devices. Its strong wavelength dependence, even for simple devices such as a single-fiber patchcord, is highlighted. Thus white sources may not be used for most measurements. We also explain the weakness of measurements with a rotating polarizer and a monochromatic source. Only a polarimeter may be used if accuracy is required. We report measurements of connections (including two connectors and one mating sleeve) and show the importance of the mating sleeve in the result. Finally, we define the validity domain of the standardized method, which uses both a white source and a rotating polarizer.