Transmission resonance induced by a d-like defect in the Fano-Anderson model with two Fano defects

Abstract

We study theoretically the propagation of waves in a discrete linear chain with two side-coupled Fano defects and one d-like defect, using a modified FanoAnderson model. Two separate cases, where the Fano defects are coupled to the chain by on-site coupling or by inter-site coupling, are considered. We find that the transmission behavior is very sensitive to whether the distance between the Fano defects and the d-like defect, l, is even or odd. In the on-site coupling case, we find that for even values of l, the FanoFeshbach resonance is sustained in the presence of a d-like defect, but the position of the transmission peak is shifted and its shape becomes asymmetric. In the inter-site coupling case, the width of the asymmetric Fano resonance can be tuned by changing the coupling constants. When l is odd in the inter-site coupling case, we find that there exist two resonant transmissions in addition to the perfect reflection. In general, the d-like defect strongly influences on the transmission resonance but does not alter the perfect reflection