Surface plasmon resonances in oriented silver nanowire coatings on optical fibers
Silver nanowires 1-3 μm in length and diameters of 0.04-0.05 μm were synthesized by a polyol process and deposited on a single mode optical fiber with the Langmuir-Blodgett technique. For nanowire surface coverage of ∼40% and partial orientation of their long axis obtained by controlling the deposition parameters, the optical properties of the nanowire coating become identical to those of a uniform metal coating obtained by sputtering or evaporation. Excitation of the nanowires by the polarized evanescent field of fiber cladding modes at near-infrared wavelengths near 1.5 μm results in surface plasmon-like resonances in the transmission spectrum of the optical fiber. The polarization-dependent loss (PDL) spectrum of the tilted fiber Bragg grating used to excite the cladding modes shows a pronounced characteristic dip indicative of a plasmon resonance for radially polarized light waves and complete shielding of light for azimuthally polarized light. The PDL dip shifts at a rate of 650 nm/(refractive index unit) when the surrounding refractive index is changed, a 10-fold increase compared to uncoated fiber gratings and similar to that of uniform metal coated gratings. The advantage of the nanowire approach is to provide a much increased contact surface area for biomolecular recognition-based immunosensing.
|Journal||The Journal of Physical Chemistry Part C|
Renoirt, J.-M. (Jean-Michel), Debliquy, M. (Marc), Albert, J, Ianoul, A.I, & Caucheteur, C. (Christophe). (2014). Surface plasmon resonances in oriented silver nanowire coatings on optical fibers. The Journal of Physical Chemistry Part C, 118(20), 11035–11042. doi:10.1021/jp5025069