Tunable chromatic dispersion compensator

One of the major bottlenecks in optical telecommunication systems is chromatic dispersion. Each frequency component of an optical pulse travels at a different group velocity, hence the pulse width broadens, thereby leading to system penalties. A demand for tunable compensators has arisen from DWDM systems with dynamic routing where the degree of pulse broadening is unknown. Another demand comes from the increased sensitivity of 40 Gb/s systems. We have suggested a novel design based on periodically poled lithium niobate (PPLN) which can compensate the dispersion of three 40 GHz channels with 200 GHz spacing in the range of 200-1000 ps/nm. Tunability is achieved by changing the ratio between the length of the sections, where the refractive index is modulated, and the length of the phase shifters. To the best of our knowledge, this is the first publication suggesting this approach.