Polarization Mode Dispersion (PMD) is the result of light traveling down a fiber along different paths. Each path will have a slightly different length, which will result in different arrival times for each component of light. The difference in arrival times is called PMD. This “differential delay” is measured in picoseconds (ps).
Chromatic Dispersion (CD) is the result of different wavelengths traveling at different speeds of the non-zero spectral width of transmitters. Since transmitters are actually made up of several wavelengths and each wavelength travels at a different speed, the difference in arrival times of each wavelength causes pulse spreading or (chromatic) dispersion. This phenomenon is measured in ps/nm.
RentalTec is providing a variety of PMD/CD testers like the single ended EXFO FTB-5700 for the FTB-2 Mainframe or the ODM E81DISPAP from VIAVI for the MTS-6000 and the optical broadband light source OBS-550