Thermally tunable dispersion compensator in 40-Gb/s system using FBG fabricated with linearly chirped phase mask

An improved design and fabrication method of nonlinearly chirped fiber Bragg gratings is demonstrated. Based on reconstruction-equivalent-chirp method, the nonlinearly chirped fiber Bragg grating is realized with a linearly chirped phase mask instead of a uniform one, which improves the performance of the device. Coated with uniform thin metal film, the obtained grating works as a tunable dispersion compensator with a tuning range ~200ps/nm, peak-to-peak group delay ripple <14ps and 3-dB bandwidth≈2nm Employing this device, the power penalty in a 40-Gb/s × 5/10km conventional single mode fiber using carrier suppressed return-to-zero format is less than 0.7dB at a BER=10-10.