Polarization-independent omnidirectional defect modes in Bragg gaps of one-dimensional photonic crystals

To minimize the dispersion of defect modes in the Bragg gap of a conventional one-dimensional photonic crystal (1D PC) doped with a defect layer of left-handed material (LHM), a numerical technique is developed for tuning the optimized parameters of the defect. Through a defect couple comprising a pair of adjacent right-handed material and LHM defect layers, omnidirectional defect modes (ODMs), within a determined tolerance limit, are generated and shown to be much less dispersive than some recently reported near-zero dispersion defect modes. A defect couple with a dispersive LHM yields multiple near-zero dispersion channels in the bandgap. We propose the defect-couple 1D PC as a design for generating polarization-independent ODMs.