INVESTIGATION OF OPTICAL TRANSMISSION THROUGH A GOLD GRATING WITH SEMICIRCLE BUMPS USING FDTD METHOD

Abstract

The optical transmissions through a gold grating with semicircle bumps were investigated using finite difference time domain (FDTD) method. As the semicircle bumps are set symmetrically in the slits, the resonant peaks for even modes exhibit a redshift, while odd modes exhibit a blueshift compared with the resonant peaks of the smooth slit grating. When the semicircle bumps are set asymmetrically, obvious resonant dips in the transmission spectrum appeared and they can be modulated by shifting the position of bumps in one slit and changing one slit width. Based on the electric and magnetic field distributions, Fabry–Pérot-like resonance, field interference and phase resonance mechanisms have been suggested for the physical origins of these observations.