Near-field Characterization on Light Emanated from Subwavelength Plasmonic Double Slit of Finite Length

Abstract

Near-field properties of light emanated from a subwavelength double slit of finite length in a thin metal film, which is essential for understanding fundamental physical mechanisms for near-field optical beam manipulations and various potential nanophotonic device applications, is investigated by using a threedimensional finite-difference time-domain method. Near-field intensity distribution along the propagation direction of light after passing through the slit has been obtained from the phase relation of transverse electric and magnetic fields and the wave impedance. It is found that the near field of emerged light from the both slits is evanescent, that is consistent with conventional surface plasmon localization near the metal surface. Due to the finite of the slit, the amplitude of this evanescent field does not monotonically approach to than of the infinite slit as the slit length increases, i.e. the near-field of the longer slit along the center line can be weaker than that of the shorter one.

Funneling of Oblique Incident Light through Subwavelength Metallic Slits

“…Takakura [ 4 ] performed an analysis of a single slit in a perfect electric conductor (PEC) and obtained the Fabry–Perot resonance wavelength. The detailed mechanisms and many different subwavelength structures have been studied [ 14 , 15 , 16 , 17 , 18 , 19 ] because of their importance for academic research. It also has numerous applications [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], such as in plasmonic lattices used as couplers to guide energy in an underneath subwavelength titanium dioxide layer, resulting in photonic crystal slabs [ 30 ].…”