Figure 1: Optical properties of the capped aluminum nanoslits.
From: Highly Sensitive Aluminum-Based Biosensors using Tailorable Fano Resonances in Capped Nanostructures
(a) The optical image of the capped aluminum nanoslit arrays on an A4 size polycarbonate film. There are 416 arrays and the area of each periodic nanostructure is 5 × 5 mm2. The inset shows a schematic configuration depicting the geometrical parameters of the capped aluminum nanoslits and the direction of the transverse magnetic (TM)-polarized incident light. (b) Measured transmission spectra of the 470-nm-period capped aluminum nanoslits in air and water for normally incident TM-polarized light. We chose H = 35 nm, T = 42 nm, W = 60 nm, and P = 470 nm for the structure. The inset shows the Breit-Wigner-Fano fitting curve of the Fano resonance in air environment. According to the fitting equation of the Fano resonance, the linewidth (w) and Fano factor (q) was 2.7 nm and −1.13, respectively. (c,d) The measured angular transmission diagram of 470-nm-period capped nanoslit arrays with a 42-nm-thick aluminum film in air (c) and water (d) for TM-polarized incident light, respectively. The solid lines show the theoretical resonance wavelengths (calculated using eqs (4) and (5)) for the SPR modes and Wood’s anomaly, respectively.
