The filtering characteristics of multiple ring resonator (MRR) filters are modeled and investigated. The ring resonators of the MRR have identical perimeters and the coupling coefficients distribution provide passband characteristics with steeper roll-off, flatter top and greater stopband rejection than single ring resonator. The theoretical results are indicated that the optical loss in micro-rings has a strong influence on the characteristics of the MRR filters. A novel attempt has been made to employ a graphical approach in the analytical derivation of the optical transfer functions of MRR filters that can be represented in signal flow graph diagrams. (C) 2007 Elsevier GmbH. All rights reserved.