Single-photon source engineering using a Modal Method

Solid-state sources of single indistinguishable photons are of great interest for quantum information applications. The semiconductor quantum dot embedded in a host material represents an attractive platform to realize such a single-photon source (SPS). A near-unity efficiency, defined as the number of detected photons by the collection optics per trigger, is desired, and to obtain this high efficiency the photonic environment must be engineered [1] such that all the emitted light couples to the collection optics. A recent design approach is based on a quantum dot placed inside a photonic nanowire (Fig. 1). This structure does not feature a cavity but instead relies on a geometrical screening effect to efficiently couple photons to the fundamental waveguide mode. Furthermore, the photonic nanowire SPS implements a bottom metal mirror and exploits tapering strategies based on conical tapers to ensure efficient in- and out-coupling. However, the performance of the photonic nanowire SPS depends critically on the geometrical parameters, and exact optical simulations of the scattering coefficients of the fundamental waveguide mode are required to obtain a detailed understanding of the various subcomponents. The natural choice of simulation method for the SPS design is thus a Modal Method, which allows for a determination of scattering coefficients in an elegant way. In this presentation, I will describe the Modal Method as well as its application to novel designs of highly efficient photonic nanowire SPSs