Low crosstalk intersections of CCWs composed by mono-mode cavities

Low crosstalk intersections formed by two crossing coupled cavity waveguides (CCWs), which are formed by series of \textit{mono-mode} cavities in a two dimensional photonic crystal structure, are investigated. Although the individual cavities are \textit{mono-mode}, the modes of the properly designed CCWs (which are called \textit{supermodes} in this paper) may be dipole-like, and antisymmetry along the axis of the other perpendicular CCW, which ensures the low crosstalk of the intersections. According to the results of coupled mode analysis, we divide the intersections into two kinds based on the number of cavities of each CCW, and the transmission and crosstalk spectra of both kinds are numerically obtained using finite difference time domain (FDTD) method. The results show that crosstalk power is lower than -30dB. We also discuss the factors that affect the performance of the intersections.