  In this letter, we investigate the coherent tunneling process of photons
between a defected circular resonator and a waveguide based on the recently
developed discrete coordinate scattering methods (L. Zhou et al., Phys. Rev.
Lett. 101, 100501 (2008)). We show the detailed microscopic mechanism of the
tunneling and present a simple model for defect coupling in the resonator. The
Finite-Difference Time-Domain(FDTD) numerical results is explored to illustrate
the analysis results.
