Fitting experimental dispersion data with a simulated annealing method for nano-optics applications

A considerable amount of materials in nanophotonics are dispersive, enabling the propagation of the so-called surface plasmons at their interfaces with dielectrics. Hence, a reliable fit of frequency-dependent permittivity functions with an appropriate model is a first-order necessity for the accurate design of nano-optics devices with time-domain numerical methods, such as finite-difference time-domain or discontinuous Galerkin time-domain. We present the necessary ingredients to fit experimental permittivity functions using the simulated annealing method with a generalized second-order dispersion model implemented in the Diogenes software suite. By scanning through different classes of materials, we came up with effective rules of thumb to make the fitting process fast and accurate. (C) 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)