Optimization of 1D Silver Grating Devices for Extraordinary Optical Transmission

Abstract

This paper reports the behavior of extraordinary optical transmission (EOT) through 1D plasmonic nanostructure devices when thickness and periodicity of silver film simulated on glass substrate are fixed and only slit width is varied. Transverse magnetic (TM) polarized photon incident normally at the grating structure and zero-order transmission spectra has been extracted. Fano-resonance associate with the excitation of the surface plasmon polaritons (SPPs) has been evaluated carefully to calculate EOT. Excited plasmons along with the Febry-Perot mode have contributed toward the EOT through the periodic slits in the grating device. It has been found that its numerical value of EOT is maximum at a particular slit width, i.e., 409 nm, which is greater than one half and less than two third of periodicity, when wavelength of light is comparable with periodicity. This unique behavior is associated with the maximum incident energy coupled to the excited plasmon due to fundamental plasmonic mode being the most efficient. Such optimal devices find many applications in real world, e.g., light-emitting diodes (LEDs), biosensing, and SERs.