Design of wideband and low group velocity based on coupled cavity waveguides

A method is proposed to design wideband and low group velocity in coupled cavity waveguide (CCW). By tuning the position of the defect row, the first and second rows adjacent to the defect row in the photonic crystal, the guided band is tailored. As a result, the group velocity can be decreased, with a relatively broad bandwidth of the guided band. The effects of three parameters on the group velocity of the crystal are analyzed in detail, using 2D plane wave expansion method. We numerically demonstrate that the group velocity of 0.0096c with 3.0 nm bandwidth of the guided band can be obtained in the model. Viewed from an actual standpoint, this tuning position method has its advantage in fabricating than the method of controlling the diameters of rods or holes.