Frequency Dependence of Polarization Mode Dispersion in a Crystal-Based Polarization Mode Dispersion Compensator

We report the frequency dependence of polarization mode dispersion (PMD) in a PMD compensator based on six cascaded birefringent crystals separated by Faraday rotators. When all crystal axes are aligned, the device can compensate for the first-order PMD. However, if all crystal axes are coupled with arbitrary angles, it can compensate for high-order PMD. The variations of differential group delay and principal state of polarization with optical frequency are analysed. The PMD vector and Stokes components of the device versus wavelength are measured. The theoretical simulations agree well with the experimental results.