| 摘要 |
A system for measuring polarization mode dispersion (PMD) in a fiber using a polarizer controlling the polarization state of light input to the fiber and a polarization analyzer measuring the polarization state of light output from the fiber. Jones matrix analysis is applied to data derived from three input polarization states and two wavelengths of probing radiation. Performance is improved by using incoherent light sources such as light emitting diodes in conjunction with two bandpass filter. However, a laser source and optical detector are used to align the fiber. The system is particularly useful in measuring PMD values in short lengths of fiber and mapping those values with a long fiber from which the test fiber was cut. Preferably, the PMD is measured for various values of twist experimentally induced in the test fiber, and the short-length PMD value is that associated with zero-internal twist in the fiber as calculated according to a model. The fiber may also be loaded during measurement. |
