Transmission and dispersion of coupled double-ring resonators

Based on the symmetry between the transfer characteristics of two coupled double-ring resonators (CDRRs) with symmetrical loss and gain distributions, the transmission and dispersion characteristics of CDRRs with gain in both rings and gain in one ring and loss in the other are analyzed systematically. It is shown that besides coupled-resonator-induced transparency and absorption as in total lossy structures, transmission spectra of inverse transparency and absorption can also exist when gain is introduced. The lasing threshold, classification of transmission response, and group velocity control of different loss and gain structures at resonance and split modes are provided. (C) 2011 Optical Society of America