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

Abstract

Photonic crystal (PC) coupled cavity waveguides (CCWs) with \textit{completely separated eigenfrequencies} (or supermodes) are investigated. Using a coupled mode theory, the properties of the supermodes, such as the electric field profiles, the eigenfrequencies (including the central frequencies and corresponding linewidths), and the quality factors (Qs) are expressed in very simple formulas, and these results agree well with those of ``exact'' numerical method. We also discuss the great differences between the supermodes and \textit{continuous modes}, which are described by tight binding (TB) theory. Then, the properties of supermodes are used to investigate their potential applications in multichannel (covering the whole C-band) bistable switchings, and bistable loops are obtained numerically. We also predict and verify that all the thresholds are uniform inherently.