Green's function approach to study plasmonic luminescence enhancement in grated multilayer structures

Surface plasmons (SPs) have recently gained substantial attention due to their sub-wavelength localization and strong interactions in the near-field. Their unique properties are expected to be essential for the next-generation photonic nanodevices, for instance, to improve light extraction in light-emitting diodes (LEDs). We discuss and develop a rigorous and transparent method to model luminescence enhancement and absorption in grated multilayer structures. The method is based on Green's functions, obtained as a perturbative solution to Maxwell's equations, and the fluctuational electrodynamics description of the structures. The model provides an analytical alternative to numerical methods such as finite-element methods and gives insight beyond the numerical solutions, offering a direct means of studying emission and luminescence from the periodic structures. The model is applied to answer key fundamental questions regarding luminescence enhancement, absorption and reflection in realistic plasmonic GaN light-emitting diode (LED) structures. Two aspects are considered in particular: (1) modeling the reflectometry measurements of grated LED structures to explain and map the interference patterns observed experimentally by our collaborators, and (2) modeling the enhancement in plasmonic structures where the emission takes place in quantum wells in the vicinity of the metallic grating. The results clearly reveal e.g. the SP-related luminescence enhancement in InGaN quantum well structures incorporating periodic silver grating.