Optical Studies Of Subwavelength Structures

ABSTRACT: In this study we have studied optical properties of subwavelength structures. There is still a debate about possible mechanisms responsible for enhanced optical transmission of subwavelength structures. Two different works have been produced to better understand the physics of enhanced optical transmission: hole arrays in silver films and bullseye structures. In hole arrays, the period of the grating and hole size are systematically varied to give peak transmittances at different wavelengths. The spectra coincide when scaled using the array geometry and this shows independence of the dielectric function of the metal. We conclude that the spectra can be explained by interference of diffractive and resonant scattering. The resonant contribution is due to electromagnetic modes trapped inside the structures. In bullseye structures we have shown enhanced transmission without apertures due to trapped modes and cavity resonances.