Coupling characteristics of surface modes in truncated two-dimensional photonic crystals

We investigate the coupling properties of localized modes between two identical truncated triangular photonic crystals composed of air holes in a dielectric background. The frequency of even parity modes varies more sensitively to the distance between the truncated faces of the crystals; i.e., the coupling distance. This behavior is explained in terms of photonic bands and spatial distribution of fields. This localized mode with even parity is shown to be a good guided mode from the finite-difference time-domain simulation. The guided range can be tuned by varying the coupling distance and the degree of truncation.