# Gold Nanoparticle-Enhanced Dual-Channel Fiber-Optic Plasmonic Resonance Sensor

## TL;DR

A new fiber-optic sensor design using gold nanoparticles and a TiO2/Au bilayer boosts sensitivity for detecting biochemical substances in low-refractive-index environments.

## Contribution

A dual-channel D-shaped PCF-SPR sensor with a TiO2/Au bilayer and gold nanoparticles for enhanced hybrid plasmonic coupling and field confinement.

## Key findings

- The sensor achieves a maximum wavelength sensitivity of 16,600 nm/RIU.
- Sensitivity is improved by 1.47× compared to conventional PCF-SPR designs.
- Gold nanoparticles significantly enhance the interaction between the electric field and the analyte.

## Abstract

What are the main findings?
A dual-channel D-shaped PCF-SPR sensor integrating a TiO2/Au bilayer with gold nanoparticles achieves strong hybrid plasmonic coupling and significantly enhanced field confinement.The optimized structure reaches a maximum wavelength sensitivity of 16,600 nm/RIU and improves sensing performance by 1.47× compared to conventional PCF-SPR designs.

A dual-channel D-shaped PCF-SPR sensor integrating a TiO2/Au bilayer with gold nanoparticles achieves strong hybrid plasmonic coupling and significantly enhanced field confinement.

The optimized structure reaches a maximum wavelength sensitivity of 16,600 nm/RIU and improves sensing performance by 1.47× compared to conventional PCF-SPR designs.

What are the implications of the main findings?
The demonstrated hybrid LSPR–SPP enhancement mechanism provides an effective strategy for boosting sensitivity in low-refractive-index biochemical environments.The proposed design offers a feasible pathway for developing next-generation high-performance optical fiber sensors for biochemical detection and environmental monitoring.

The demonstrated hybrid LSPR–SPP enhancement mechanism provides an effective strategy for boosting sensitivity in low-refractive-index biochemical environments.

The proposed design offers a feasible pathway for developing next-generation high-performance optical fiber sensors for biochemical detection and environmental monitoring.

Surface plasmon resonance (SPR) sensors based on photonic crystal fibers (PCFs) hold significant promise for high-precision detection in biochemical and chemical sensing. However, achieving high sensitivity in low-refractive-index (RI) aqueous environments remains a formidable challenge due to weak light-matter interactions. To address this limitation, this paper designs and proposes a novel dual-channel D-shaped PCF-SPR sensor tailored for the refractive index range of 1.34–1.40. The sensor incorporates a dual-layer gold/titanium dioxide film, with gold nanoparticles deposited on the surface to synergistically enhance both propagating and localized surface plasmon resonance effects. Furthermore, a D-shaped polished structure integrated with double-sided microfluidic channels is employed to significantly strengthen the interaction between the guided-mode electric field and the analyte. Finite element method simulations demonstrate that the proposed sensor achieves an average wavelength sensitivity of 5733 nm/RIU and a peak sensitivity of 15,500 nm/RIU at a refractive index of 1.40. Notably, the introduction of gold nanoparticles contributes to an approximately 1.47-fold sensitivity enhancement over conventional structures. This work validates the efficacy of hybrid plasmonic nanostructures and optimized waveguide design in advancing RI sensing performance.