Multi-channel slow light coupled-resonant waveguides based on photonic crystal with rectangular microcavities

The light transmission characteristics through the coupled-resonator optical waveguides (CROWs) based on the two-dimensional square-lattice photonic crystal with rectangular microcavities are systematically studied by the finite-difference time-domain method. Owing to the multiple spatial symmetries of the defective modes localized by the rectangular microcavities, the guiding bands can be adjusted by changing the coupling region between the CROW and the traditional W1-typed input and output channels, and their corresponding group velocities can be quite different from each other through the same CROW structure. Through optimizing the coupling regions between the CROW and three output channels, a kind of device with both the abilities of light beam splitting and frequency selection can be obtained, which has potential applications in the future complex all-optical circuits.