Abstract
Two-dimensional finite-difference time-domain (FDTD) method has been performed to numerically investigate the transmission through a one-dimension cupped surface metallic grating structure. The concept of coupling of optical modes in the notches and main slits, introduced by Crouse and Keshavareddy [1], is examined further in our work. Unexpected phenomenon is shown that even horizontal surface plasmons (HSPs) are inhibited, the transmission still can be enhanced or suppressed. And the periodicity of transmission depending on the phase change of the light striking on the grating surface is discovered. A hybrid optical mode combined by cavity mode and diffracted evanescent wave mode [2] is introduced to analyze the phenomenon.
Highlights
Since Ebbesen first reported the extraordinary optical transmission through a two-dimensional (2-D) hole array perforated on a metallic film in 1998 [3], optical properties of periodically subwavelength metallic structures have attracted a considerable interest during the past years [4,5,6,7,8]
We investigate further about the concept of coupling between optical modes in the notches and main groove introduced by Crouse and Keshavareddy [1] and analyze the phenomenon that transmission can be enhanced or suppressed when horizontal surface plasmons (HSPs) are inhibited
Through discussing with the cted evanescent wave (CDEW) model [2], we consider that transmission is controlled by a CDEW/cavity mode (CM) hybrid optical mode, and the phase change of light striking on surface of grating is a key factor to this hybrid mode
Summary
Since Ebbesen first reported the extraordinary optical transmission through a two-dimensional (2-D) hole array perforated on a metallic film in 1998 [3], optical properties of periodically subwavelength metallic structures have attracted a considerable interest during the past years [4,5,6,7,8]. The present common understanding of the mechanism responsible for this extraordinary enhanced transmission is the excitation of surface plasmon (SPs) at the interfaces of the structured film [3,4,5,6,7]. Cao and Lalanne [8] have argued that the resonant excitation of surface SPs suppresses the transmission in the 1-D gratings. We find that even if HSPs are inhibited in this structure, the transmission still can be enhanced or strongly suppressed
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