Optical Properties of Direct and Indirect Coupling of Cascaded Cavities in Resonator-Waveguide Systems

摘要

By using the coupled-mode theory-based transfer matrix, we analyze the optical properties of direct and indirect coupling of cascaded cavities in the resonator-waveguide system. The dispersion relation of the system, bandgap opening mechanisms, and anticrossing behavior are investigated theoretically and numerically. We also derive the transmission coefficients of the direct and indirect coupling system with multiple cavities and demonstrate the interaction between the modes, which leads to Fano resonance with an asymmetric transmission line shape. All the results obtained by the transfer matrix method are confirmed by the finite-difference time-domain method in photonic crystals.