Photonic crystal fiber assisted nano-antenna for tip-enhanced Raman spectroscopy

Metallic plasmonic nano-probes can efficiently excite and detect the near-field 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 probe. In our device, light in a photonic crystal fiber (PCF) couples with the surface plasmons of a nano-antenna. The needle-shaped antenna is grown by electron beam assisted chemical deposition of platinum on the PCF’s end facet. Plasmonic resonance conditions can be optimized by controlling the deposition parameters, height, and base diameter of the antenna. 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.