Nanophotonics engages with light–material interaction behaviors that occur on wavelength or subwavelength scales, where the electromagnetic field is confined to the surface of designed nanostructures with unique and tunable optical properties. In particular, “plasmonics” using surface plasmon polaritons (SPPs), simply called surface plasmon, is diverse and a rapidly growing field in nanophotonics. The optical properties of materials are described by their complex dielectric function, which are composed of real and imaginary parts at a given wavelength of incident light. Simply, this function can characterize the polarization of materials interacting with electromagnetic waves because most materials behave differently to incident electromagnetic waves with different wavelength. Surface-enhanced Raman scattering (SERS) requires a substrate that has structure and can enhance the Raman scattering to detect an analyte of interest effectively. The developments of SERS substrate have been extensively performed using nanoparticles or nanostructures to create a uniform and higher number of “hot spots” as much as possible for large local field enhancement.