, Volume 6, Issue 1, pp 35-42
Date: 15 Sep 2010

Computational Study of Influence of Structuring of Plasmonic Nanolens on Superfocusing

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The focusing effect of the plasmonic nanolens is studied systematically. The influence of different construction parameters including the size of the central hole, the ring width of the surrounding concentric grating, the thickness of the metal film, and the distance of the central hole to grating has been simulated by rigorous finite difference time domain method and analyzed. It is found that the intensity of the central nano-spot is linearly proportional to the size of the central hole and inversely linearly proportional to the thickness of the metal film. In addition, the intensity of the lobes can be suppressed effectively by reducing the ring width down to a quarter of plasmon wavelength to achieve a better focusing effect. The influence of the distance of central hole to grating is a little bit complex, but generally, the intensity for the distance of (2n − 1)/2 plasmon wavelength is larger than the case of the distance of nλSP. The simulation results can be a general guide for the design of plasmonic nanolenses.