Optical Enhancement by Gold Nanoring-Nanodisk Plasmonic Structures for Light Sensing Applications

We design and numerically model a 3D nanoring-nanodisk structure and evaluate the effect of the ring and the disk radii size within the presented structure on optical enhancement. Nanoring-nanodisk is a powerful structure for enhancing the local electric field for photo-sensing applications. We present an enhanced local electric field from the UV to IR wavelength range using the proposed structure with a fixed nanogap. It shows a strong dependence on the disk radius of the structure. In addition, two distinct peaks have different plasmonic vibrational modes appearing in the spectrum. These modes are revealed by 3D surface charge and local electric field distributions. Moreover, our calculations reveal that a smaller disk radius with a larger ring radius can generate more optical enhancement.