Control of EOT on sub-wavelength Au hole arrays via Fano resonances

Abstract In this work, we explore extra-ordinary-transmission (EOT) behavior where localized and propagating surface plasmon fields due to the sub-wavelength periodical holes in a relatively thick metal film (opaque) are under an interaction with two-level quantum emitters. First, the transmission properties (plasmon modes, electrical field amplitudes etc.) of Au hole arrays are investigated through FDTD analysis. Then, the physics behind this interaction, also known as Fano resonance or path-interference, is explained. In addition, numerical analysis and FDTD simulations are performed to enhance/suppress near field localization to control the strength of EOT signal. Moreover, suppression of EOT signal is obtained through FDTD simulations by solving Maxwell’ equations while acquiring its bulk-sensitivity. As the spectral position of plasmon peak changes due to change in refractive index of surrounding environment, the suppression phenomena stays unchanged at the same spectral position. Results show that this concept could carry strong potential for sensing of fluorescent molecules whose excitation and plasmon field spectra of fabricated structure overlaps without altering the output signal of designed sensor.