Abstract
We present a method that utilizes double-sided Feynman diagrams and show it to be particularly useful for the study of coherence-induced phenomena, because the photon processes form an infinite power series. We systematically formulate the diagrammatic method and employ it to analyze electromagnetically induced transparency, interacting dark resonances, and a general N-level chain system. The method not only provides an alternate way to predict these phenomena, but also reveals the contributions from individual transition pathways.