Photonics Research, Volume. 12, Issue 10, 2166(2024)
From localized to propagating surface plasmon resonances in Au nanoparticle-coated optical fiber sensors and its implications in biosensing
Fig. 1. Optical fiber sensing scheme composed of a broadband light source and a spectrometer to measure the plasmonic NP response on the fiber optic sensing probe. This probe is based on a 1 cm core-exposed section near the optical fiber cleaved tip (onto which a silver mirror was previously deposited).
Fig. 2. A: Schematic representation of the simulation setup where the random ensemble of Au NPs immobilized over the fiber core was approximated by a gradient effective index method (GEMA). This method divides the NPs into multiple homogeneous layers with an effective RI given by Maxwell-Garnett theory. B: Real component of the effective index profile for the multiple GEMA layers at several NP coverage densities for 50 nm NPs.
Fig. 3. A: Au NP deposition kinetics onto the optical fiber sensor, showing two plasmonic bands dependent on the deposition time. The Au NP diameter is 50 nm. B: Time evolution of the wavelength shift of both plasmonic modes during 50 nm Au NP immobilization. C: Scanning electron microscope (SEM) images of the Au NPs on optical fibers at different deposition times (5, 20, and 40 min). The estimated value of NP densities on the fiber surface (
Fig. 4. A: Calculated dispersion curves for a 50 nm effective index plasmonic layer on the fiber surface at various NP densities (
Fig. 5. A: Refractive index sensitivity of optical fibers immobilized with 51 nm Au NPs with
Fig. 6. A: Experimental optical properties recorded with a 50 nm Au NP immobilized optical fiber immobilized upon changing the refractive index of the surrounding medium from water (
Fig. 7. Experimental results obtained for optical fibers coated with 70 nm Au NPs at
Fig. 8. Calculated effective index through the Maxwell-Garnett effective index approximation for distinct Au densities. The complex material refractive index is shown for its real (A) and imaginary (B) components. C: Wavelength of the effective index maxima for the Au densities ranging between 0 and 0.3.
Fig. 9. Calculated optical response from the GEMA structure for a 20 nm layer under s-polarization, p-polarization, and the sum of both (
Fig. 10. Comparison of the RI sensitivity at
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Paulo S. S. dos Santos, João P. Mendes, Jorge Pérez-Juste, I. Pastoriza-Santos, José M. M. M. de Almeida, Luís C. C. Coelho, "From localized to propagating surface plasmon resonances in Au nanoparticle-coated optical fiber sensors and its implications in biosensing," Photonics Res. 12, 2166 (2024)
Category: Surface Optics and Plasmonics
Received: Jan. 11, 2024
Accepted: Jul. 8, 2024
Published Online: Sep. 14, 2024
The Author Email: I. Pastoriza-Santos (pastoriza@uvigo.gal)
CSTR:32188.14.PRJ.518181