High performance lithium niobate polarization controller for PMD compensators

摘要

Polarization mode dispersion (PMD) is a major barrier to achieve 40 Gbit/s transmission over a long distance. A PMD compensator is required to reduce pulse distortion for systems operating at date rates greater than 10 Gbit/s. The polarization controller is the key component in a optical/optoelectronic PMD compensator. Several technologies are available to make a polarization controller, among them are mechanically rotating crystal waveplates or fiber loops, squeezing fiber or quartz with piezo electric elements, and electrically tuned liquid crystal waveplates. These polarization controllers are good for laboratory experiments and for test/measurement equipment applications, but not suitable to be used in fiber optic communication systems because their performance and reliability are questionable. Mechanical rotation is bulky and slow; piezo squeezers have hysteresis; liquid crystal is temperature sensitive. In this paper, we will present experimental results on a polarization controller that is based on electro-optic effect of Ti diffused optical waveguide in lithium niobate. It is fast, small, broadband, temperature insensitive and highly reliable.