Rayleigh-Wood anomaly approximation with FDTD simulation of plasmonic gold nanohole array for determination of optimum extraordinary optical transmission characteristics

Light confinement in small volumes remains one of the old and important challenges in the realm of optics. One of the widely studied phenomena of light confinement is extraordinary optical transmission (EOT) through holes with a radius much smaller than the wavelength of light. However little work has been done to provide a phenomenological study detailing underpinnings of the numerical evaluation. To this end, we investigate the Rayleigh-Wood anomalies arising from a plasmonic gold thin film nanohole array on glass through theoretical calculations and FDTD simulations. Theoretical investigation of Rayleigh-Wood anomaly provides an approximation of optical transmission features independent of hole geometrical shape. A discussion is presented on the relation between EOT and Q-factor at various orders. A rational is provided as to why elliptical (i.e round and anisotropic) nanohole array leads to optimum transmission characteristics. It is expected that our results will have an important role in the characterization and optimization of EOT based nanophotonic devices such as plasmonic biosensors, photovoltaics, IR detectors and rotation sensors.