Broadband all order polarization mode dispersion compensation using liquid -crystal modulator arrays

Mehmetcan Akbulut, Purdue University


Polarization Mode Dispersion (PMD) is a serious barrier that limits high-speed optical fiber telecommunication systems. PMD is the result of random birefringence in single-mode fibers along the transmission path. This leads to wavelength-dependent polarization states and phases at the output that eventually result in pulse deformations and system outages. Of course, things get worse with increasing bandwidth of the optical signals. Several techniques have been proposed to measure and compensate for PMD. Although the measurements can be implemented for large bandwidths, the compensation ideas only work for small bandwidths where the PMD effects are not as drastic. Another weak side of the proposed compensators is that they are serial devices, i.e. every input wavelength receives the same type of treatment. Motivated by this, we have constructed a PMD compensation scheme where all wavelengths can be compensated separately, and it works for moderately large bandwidths depending on the application. In this work, we demonstrate the application of ultrafast pulse shaping techniques for experimental wideband all-order PMD compensation, for the first time to our knowledge. PMD is treated as arbitrary variations of State of Polarization (SOP) and Phase vs. wavelength, in an all-order sense. Consequently, two pulse shapers are implemented in a serial manner to compensate the polarization and phase spectra independently. The first step corrects the wavelength-dependent polarization states to a fixed x or y state. Furthermore, the second step equalizes the spectral phase to restore the clean input pulse. We report compensation of sub-picosecond pulses (14 nm bandwidth around 1550 nm) that are anomalously spread to more than 2 ps due to PMD. This PMD compensation scheme can potentially be a powerful and cost-effective solution for ultra high capacity fiber optic telecommunication networks.




Weiner, Purdue University.

Subject Area

Electrical engineering

Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server