Nanometric Plasmonic Rulers Based on Orthogonal Plasmonic Gap Modes in Metal Nanoblocks

• Main Authors: Tae-Woo Lee, Young Jin Lee, Eunso Shin, Soon-Hong Kwon
• Format: Article
• Language: English
• Published: MDPI AG 2018-03-01
• Series: Applied Sciences
• Subjects: surface plasmon; plasmon ruler; sensor; nanoparticles
• Online Access: http://www.mdpi.com/2076-3417/8/3/386

We theoretically propose a three-dimensional (3D) plasmonic ruler based on orthogonal plasmonic gap modes which have different wavelengths. The ruler consists of three silver nanoblocks with two ten-nanometer air gaps. First, in a two-block structure, the lateral displacement of one block can be determined by the absorption spectrum, in which two orthogonal modes are observed with different wavelengths. Secondly, in a three-block structure, due to the distinctive wavelength dependencies on the x- or y-directional movement of the two orthogonal modes and the strong dependencies on the air gap size, the 3D positioning of one nanoblock relative to a reference nanoblock can be measured with a 2.5 nm resolution using the spectral positions of the absorption spectrum.