Optical Nano-antenna on Photonic Crystal Fiber*

Metallic nanowire probes supporting plasmon polariton modes can localize the optical fields at nanoscale for near-field imaging and sensing applications such as tip-enhanced Raman spectroscopy (TERS). In this paper, we report the design, fabrication and far-field characterization of a photonic-plasmonic optical fiber probe where light in a photonic crystal fiber (PCF) couples with the surface plasmons of a nanowire optical antenna. The needle-shaped antenna is grown by electron beam assisted chemical deposition of platinum on the PCF’s end facet. By controlling the deposition parameters, height and base diameter of the antenna can be tuned to optimize plasmonic resonance conditions. Far field emission to the side of the probe, optical spectra and mode profiles transmitted through the probe demonstrate the excitation of surface plasmons on the antennae. The probe can be implemented into TERS setup to obtain spectroscopic information at the nanoscale.