Polarization-dependent hotspots formed in crossed silver nanowires for surface-enhanced Raman spectroscopy

Well-defined metal nanostructures with highly tunable optical properties are promising substrates for surface-enhanced Raman scattering (SERS) research and applications. In this paper, we present a crossed junction to create plasmonic hotspot, which was fabricated by the micromanipulation of chemically synthesized silver nanowires. The field enhancements were evaluated via the detection of Raman spectra by the means of local and remote excitation, respectively. The experimental investigation and numerical simulation of dependence on polarization direction were performed. The nature of the polarization dependent enhancement is further discussed. This work would be valuable for studying properties of more complex regular nanostructure, such as 3-dimensional structures consisting of nanogaps and vertical stacking, for ultrahigh-enhancement SERS.