A flat-based plasmonic fiber probe for nanoimaging

The difficulty of obtaining high-intensity localized light spots for optical probes leads to their lack of good applications in nanoimaging. Here we demonstrate a Fabry–Pérot resonance flat-based plasmonic fiber probe (FPFP). The simulation results show that the probe can obtain a nanofocusing spot at the tip with the radially polarized mode. The Fabry–Pérot interference structure is used to control the plasmon propagation on the surface of the probe, and it effectively improves the local spot intensity at the tip. Furthermore, the experimental results verify that the FPFP (tip curvature radius is 20 nm) prepared by chemical etching method can obtain a nanofocusing spot at the tip. The nanoimaging of the gold slit structure demonstrates the nanoimaging capability of the FPFP, and the 36.9 nm slit width is clearly identified by the FPFP.