Extraordinary optical transmission in one-dimensional gold gratings: near- and far-field analysis

The Influence of Substrate on the Optical Properties of Gold Nanoslits

Nanoslits have various applications, including localized surface plasmon resonance (LSPR)-based nanodevices, optical biosensors, superfocusing, high-efficiency refractive index sensors and chip-based protein detection. In this study, the effect of substrates on the optical properties of gold nanoslits placed in free space is discussed; for this purpose, glass BK7 and Al2O3 are used as substrates and the wavelength of incident light is supposed to be 650 nm. The optical properties, power flow and electric field enhancement for gold nanoslits are investigated by using the finite element method (FEM) in COMSOL Multiphysics software. The effect of polarization of an incident electromagnetic wave as it propagates from a gold nanoslit is also analyzed. As special case, the effect of glass and alumina substrate on magnetic field, power flow and electric field enhancement is discussed. The goal of this research is to investigate the phenomenon of power flow and electric field enhancement. The study of power flow in gold nanoslits provides valuable insights into the behavior of light at the nanoscale and offers opportunities for developing novel applications in the field of nanophotonics and plasmonics. The consequences of this study show the significance of gold nanoslits as optical nanosensors.

Tuning the magneto-optical Kerr effect by the nanograting cross section

The magneto-optical Kerr effect, especially the Kerr slope, is of great significance to magneto-optical devices. Herein, we developed a method to tune the magneto-optical effect by the nanograting cross section. Both the simulation and experiment confirm that the resonance strength of the plasmon can be modulated by the nanograting cross section, resulting in the large Kerr slope and Kerr rotation. By designing the nanograting cross section, we obtained the Kerr slope of 0.397°/nm, which is 4 orders of magnitude higher than the reported results. And the Kerr rotation of the magnetic nanograting reaches up to 1.218°, which is 24 times higher than the flat Co film. Such a huge enhancement on the Kerr slope and the Kerr rotation may have profound applications in magneto-optical devices in the future.

Efficient biosensing through 1D silver nanostructured devices using plasmonic effect

The current work explores the excitation of surface plasmon polaritons (SPPs) on a one dimensional (1D) silver nano-grating device, simulated on glass substrate, which can sense a very small change in the refractive index of an analyte adjacent to it. The most recent modeling technique finite element analysis is applied in this work by using a COMSOL RF module. The models of 1D grating devices of different slit widths with fixed periodicity and film thickness are simulated. The data is collected and then used to study higher refractive index unit per nanometer (RIU/nm) as well as the effect of the widths of the slits on the RIU. A number of investigations are done by the simulated data, like a dip in the transmission spectra of p-polarized light. This dip is due to SPP resonance with the variation of slit width. Furthermore, the most fascinating part of the research is the COMSOL modeling that provides an opportunity to look into factors affecting higher RIU/nm, while visualizing the cross-sectional view of the grating device and strong electric field enhancement at the surface of the metallic device. When the slit width is almost equal to half of the periodicity of the grating device, SPP resonance increases and it is at maximum for the slit width equal to two-thirds of the periodicity, because the coupling efficiency is at maximum.