Optical modeling of superconducting nanowire single photon detectors using the transfer matrix method

We present optical modeling of superconducting nanowire single photon detector devices using an analytical approach based on the transfer matrix method. We find that the optimal dielectric layer thicknesses vary slightly with the thickness and fill factor of the NbN layer and explore novel device geometries that can be described as a stack of thin films, such as devices on multilayered substrates, free-standing membranes, and optical fiber facets. In addition, the analytical results here show the importance of accounting for coherence correctly when an integrated cavity is included in the device structure and the relative insignificance of an anti-reflection coating in most cases.