Supermodes of photonic crystal CCWs and multimode bistable switchings with uniform thresholds

Photonic crystal (PC) coupled cavity waveguides (CCWs) with completely separated eigenfrequencies (or supermodes) are investigated. Using a coupled mode theory (CMT), the properties of the supermodes, such as the eigenfrequencies (including the central frequencies and corresponding linewidths), the quality factors (Qs) and the electric field profiles, are expressed in very simple formulas, and these results agree well with those derived from transfer matrix method (TMM). We discuss the great differences between the supermodes and continuous modes, which are described by tight binding (TB) theory. Then, the potential application of supermodes as a multi-channel (covering the whole C-band) bistable switching is investigated. Using the results of CMT, we predict that the thresholds of all the channels are uniform, and verify this prediction using nonlinear transfer matrix method.