Automatically tracked dispersion compensation with penalty-free tunable dispersion equalizer for 40 Gbit/s systems

The automatic control of a tunable dispersion equalizer by means of a bit error monitor was demonstrated. The tunable dispersion equalizer developed consists of a chirped fiber grating and divided thin film heaters. From the tests of the step response and the automatic DEQ control, we confirmed that the tunable dispersion equalizer based on the grating and heaters is suitable for adaptive dispersion compensation of dispersion variations caused by slowly varying environmental conditions with a fluctuation rate of several minutes or more.