Analysis of a Plasmonic Pole-Absorber Using a Periodic Structure

Junji YAMAUCHI  Shintaro OHKI  Yudai NAKAGOMI  Hisamatsu NAKANO  

IEICE TRANSACTIONS on Electronics   Vol.E101-C   No.7   pp.495-500
Publication Date: 2018/07/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E101.C.495
Type of Manuscript: INVITED PAPER (Special Section on Distinguished Papers in Photonics)
plasmonic devices,  frequency-dependent FDTD method,  trapezoidal recursive convolution,  

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A plasmonic black pole (PBP) consisting of a series of touching spherical metal surfaces is analyzed using the finite-difference time-domain (FDTD) method with the periodic boundary condition. First, the wavelength characteristics of the PBP are studied under the assumption that the PBP is omnidirectionally illuminated. It is found that partial truncation of each metal sphere reduces the reflectivity over a wide wavelength range. Next, we consider the case where the PBP is illuminated with a cylindrical wave from a specific direction. It is shown that an absorptivity of more than 80% is obtained over a wavelength range of λ=500 nm to 1000 nm. Calculation regarding the Poynting vector distribution also shows that the incident wave is bent and absorbed towards the center axis of the PBP.