Dispersion-guided resonances in two-dimensional photonic-crystal-embedded microcavities.

We analyze dispersion-based guiding of resonances in two-dimensional (2-D) photonic-crystal-embedded microcavities (PCEMs) that comprise a finite-size square lattice of submicrometer air holes embedded in a high-index contrast square microcavity. Our 2-D finite-difference time-domain simulations of waveguide side-coupled PCEMs suggest high-Q quasi-periodic multimodes within the PC first band. The Q can increase by orders of magnitude as the mode frequency approaches the band-edge frequency or as the lattice dimension increases. By mapping the Fourier transform of the mode-field distributions onto the PC dispersion surface, we show that the modes k-vectors and group velocities are pointing near the GammaM direction.