Fiber-tip plasmonic resonators for label-free biosensing

We report fabrication and implementation of fiber-tip probes with localized surface plasmon resonators for in situ biosensing applications. Gold nano-void arrays, which act as localized surface plasmon resonators were fabricated on ordinary glass coverslips and mounted on cleaved tips of multi-mode optical fibers. Plasmon resonance peak wavelength and depth are functions of gold nano-void array parameters. Array design parameters were optimized using numerical simulations to attain maximum resonance depth and peak in the near infra-red region of the optical spectrum. Sensitivity of the fiber-tip localized surface plasmon resonators to quantify change in refractive index is measured to be 535.2 nm/RIU. Proof-of-principle experimental results of biomolecular interaction analysis with functionalized fiber-tip resonators are presented.