Near-field Optical Measurement using Nano-Prism Probes

Recently, a nano-prism (NP) structure has drawn attention as an optical nano-antenna due to its exotic optical properties, while it has been extremely difficult to prepare a probe terminated with a NP for near-field optical measurement. Herein, we report a method to mass-produce pristine NP-probes. Our fabrication process allowed us to prepare \textit{NPs with sharp edge at the end of the probes,} which significantly enhanced the electric fields around the probes and made the NP-probes ideal for nano-optical applications. We performed the apertureless near-field scanning optical microscopy on gold nanoparticles using a NP-probe, revealing the field localization at the vertices of the NP. We also achieved high resolution topographic imaging on carbon nanotubes and successfully performed the tip-enhanced Raman spectroscopy (TERS) experiment on brilliant cresyl blue (BCB) molecules, revealing a significant field localization at the sharp edge of the NP. This method could be a major breakthrough and provide tremendous flexibility for near-field optical applications.