A technique to increase the dispersion and to reduce the penalties associated with group delay ripple in dispersion compensating gratings

We describe a simple technique for reducing the system penalties caused by the group delay ripple of dispersion compensating gratings whilst increasing their dispersion. We demonstrate that the ripple can be smoothened in a combination of a pair of unapodised chirped fiber Bragg gratings by applying a small temperature or strain gradient along one grating. The pair is cascaded in a 4-port optical circulator, where data is consecutively reflected. Simulated results from the transmission of a 10 Gb/s NRZ signal over 160 km of a repeaterless conventional fiber indicate eye-opening and BER performance improvement by using such a scheme.