Finite-size effect on one-dimensional coupled-resonator optical waveguides.

We study the finite-size effect on the dispersion relation, group velocity, and transmission curves of one-dimensional finite-size coupled-resonator optical waveguide (CROW) structures. Both the dispersion relation and the group velocity curves of a finite-size CROW oscillate along those of the corresponding infinite-extended ones. The oscillations can be suppressed by matching the equivalent admittance of the surrounding medium to that of the unit cell. Thelen's method is used to find the parameters of the matching layer to reduce oscillations on the group velocity and transmission spectra, and to analyze the structure parameters that determine the bandwidth and the group velocity.