Modeling of Subwavelength Gratings: Near-Field Behavior

Abstract: Subwavelength gratings, with period shorter than the incident wavelength, have garnered significant attention in the fields of photonics, optoelectronics, and image sensor technology. In this research, we delve into the scattering characteristics of these gratings by employing the 2-dimensional point dipole approximation. Additionally, we propose a version of perturbation theory that relies on Fourier decomposition to obtain analytical expressions for the near-field behavior. We validate our models using numerical techniques such as boundary and finite element analysis. Notably, we explore how parameters like the grating period and slit width affect field enhancements. We demonstrate that our models produce qualitatively accurate results even for narrow slits.