Optical characteristics of rounded silver nanoprisms

• Published in: Optical review (Tokyo, Japan) Vol. 23; no. 2; pp. 260 - 264
• Main Authors: Mori, Tomohiro, Yamaguchi, Kenzo, Tanaka, Yasuhiro, Suzaki, Yoshifumi, Haraguchi, Masanobu
• Format: Journal Article
• Language: English
• Published: Japan The Optical Society of Japan 01.04.2016
• Subjects: Atomic; Lasers; Microwaves; Molecular; Optical and Plasma Physics; Optical Devices; Optics; Photonics; Physics; Physics and Astronomy; Quantum Optics; Regular Paper; RF and Optical Engineering; Finite-difference time-domain method; Bowtie structure; Surface plasmon; Rounded corners; Nanoprism
• ISSN: 1340-6000; 1349-9432
• DOI: 10.1007/s10043-016-0188-8

We analyzed numerical optical characteristics of silver nanoprisms with rounded corners using the three-dimensional finite-difference time-domain method. The enhancement of the electric field was decreased from 240 to 13 times by introducing a large radius of curvature at the nanoprism corners such that it became a cylinder. This caused the optical multi-mode to change to single dipole mode. In the largest local electric field enhancement using the bowtie structure, which consisted of a pair of nanoprisms with rounded corners (the curvature radius and the gap distance were 8.66 and 1 nm, respectively), the electric field was enhanced by a factor of 360 at the hotspot. The bowtie structure that has non-zero curvature radii produces a larger electric field enhancement than does the single nanoprism without a curvature radius. Furthermore, the numerical simulation elucidates that the change of the curvature radius and the change of the gap distance have the same influence on the electric field enhancement.