Wavelength-tunable dual-band edge plasmon mode based on gold edge-hole plasmonic nanostructure

Metal nanostructures have attracted attention because of their unique optical characteristics derived from localized surface plasmon resonance. In this study, gold nanoholes with edge structures were designed and characterized to possess two plasmon bands at different wavelengths. These bands were assigned to the plasmon modes that generated a concentrated electric field at the tip of the individual edge structures. Furthermore, wavelengths of these bands were independently tuned from the visible to near-infrared wavelengths with shape and size of the gold nanoholes and edge structures as variables. To demonstrate wavelength tuning, a gold nanostructure with edge plasmon bands at wavelengths of approximately 785 and 1064 nm (typical laser wavelengths for surface-enhanced Raman scattering and optical tweezers, respectively) was successfully obtained via optical simulation. The results indicate that the structure designed in this study provides a guideline for the design of optical devices with efficient multiple optical functions.