Mode dispersion in biperiodic photonic crystal waveguides

We propose and analyze biperiodic photonic crystal waveguides, where there are two sets of discrete translational symmetry along the propagation direction of the photonic crystal waveguides. We present a general method based on a spatial Fourier transform for the calculation of mode dispersion in such biperiodic waveguides. We demonstrate that by modifying the periodicity of only two rows of air holes adjacent to the guiding region, we can achieve guiding through the entire frequency band gap and greatly reduce the group velocity dispersion of the waveguide mode.