# Localized Surface Plasmon Fields Manipulation on Nanostructures Using Wavelength Shifting
## 2 Materials and Methods  
We designed unit structures of I-, T-, and Y-shaped nanostructure arrays as illustrated in Figure 1a. A unit structure of I-shaped nanostructure arrays consists of a gold nanorod with a width and length of 500 nm and 2 \(\upmu\)m, respectively, on BK7 glass. A unit structure of the T-shaped nanostructure arrays consists of a nanorod and a nanowire at right angles; the width and length of this nanorod are the same as those of the I-shaped nanostructure, and the vertical nanowire has a width of 300 nm. A unit structure of the Y-shaped nanostructure arrays consists of a zigzag nanowire with a width of 300 nm, an angle of 120\({}^{\circ}\), and a connection between the nanorods that has the same length and width as those of the I-shaped nanostructures. The unit structure in each nanostructure array was determined to be widthand length of 3 \(\upmu\)m and 8 \(\upmu\)m. The height of each nanostructure was estimated to be 100 nm.  
Moreover, we employed a rigorous coupled wave analysis (RCWA) [9; 12; 29; 30; 31; 32] for theoretical calculation to quantify distributions of near-field electromagnetic fields on I-, T-, and Y-shaped nanostructure arrays when the upward light entered at an incident angle of 60\({}^{\circ}\) (in xz-plane) in the TM and TE mode. The energy levels of incident light were selected as the four most widely used wavelengths in near infrared lasers, considering the material and size of the structure (808, 1064, 1310, and 1550 nm). The 15 \(\times\) 15 spatial harmonic orders were successfully operated to explain the optical near-field characteristics by LSP in each nanostructure array without abnormal divergence.  
Based on the theoretical design, fabrication of designed structure was performed in advance to examine whether those structures could be established well as we have designed, although this research is mainly focused on theoretical research. To verify that each nanostructure can be established and employed in functional substrates of various applications, the I-, T-, and Y-shaped nanostructures were designed as presented in Figure 1a. The fabricated structures are shown in Figure 1b. In this study, we employed electron-beam (e-beam) lithography [9, 33, 34, 35, 36, 37, 38, 39] to investigate the I-, T-, and Y-shaped nanostructure arrays. Specifically, the I-, T, and Y-shaped nanostructure arrays were fabricated on a BK7 glass substrate with a thickness of 180 \(\upmu\)m. To enhance the adhesion between the glass substrate and the gold nanostructure, a 2 nm-thick chrome adhesion layer was deposited. Each nanostructure array was established using e-beam lithography (Tescan, Brno, Czech Republic) with a negative polymer resist (ma-N 2403, Micro Resist Technology, Berlin, Germany). Each nanostructured pattern was converted into a gold nanostructure array with a 100 nm-thick by the thermal evaporation of gold and by lift-off processes using a chemical developer (ma-D 525, Micro Resist Technology). Figure 1b presents the scanning electron microscopy (SEM) images of the I-, T-, and Y-shaped nanostructure arrays fabricated by the afore-mentioned processes.