Optimum condition analysis of series coupled ring resonator for very high efficiency dropping operation

This study investigates the optimum condition of coupling efficiency and clarifies that the optimum condition for the lossy case is quite different from that for the lossless case. If the resonator suffers loss, small amount of light is transmitted to the through port at the resonant frequency under the conventional maximally flat condition, and the cross talk is deteriorated. However, if the ring resonator involves loss, strong couplings between busline and resonator and between resonators are required to satisfy these conditions simultaneously. Therefore the loss in the resonator should be reduced for higher performance. In the case of higher order series coupled ring resonator, the optimum condition is given by similar approach.