Dispersion compensator based on multiple 1D coupled-defect-type photonic crystals

We have developed an ultra compact dispersion compensator based on multiple one dimensional coupled-defect-type photonic crystals, utilizing large optical group velocity dependence on the wavelength without polarization mode dependence. The photonic crystal of the compensator consists of a SiO2/Ti2O5 multi-layer thin-film structure and SiO2 defect layers and was designed for a 1.55-mu m, 40-Gbit/s optical communication system. The thin-film structure is substrate-free, which enables the compensator to be small, that is, a 1.4-mm-edge cube. To obtain a large group-velocity difference, 60 substrate-free films are stacked to form the compensator. The passband is 2 nm, and the group delay time-difference within the band is more than 100 ps. A 40-Gbit/s non-return-to-zero optical transmission experiment was carried out with the compensator, demonstrating dispersion-compensation operation over a 10-km standard single-mode fiber, which corresponds to dispersion of 170 ps/nm.