Triangular silver nanoparticle U-bent fiber sensor based on localized surface plasmon resonance

Optical sensors with local surface plasmon resonance (LSPR) of noble metal (gold, silver, platinum) nanoparticles have received extensive attention due to their excellent detection performance. Here, we propose an LSPR fiber-optic sensor with a graphene oxide/triangular silver nanoparticle structure. Benefiting from the LSPR characteristics of the silver triangle nanoparticles, the use of triangular silver nanoparticles provides significant sensitivity enhancement. In order to highlight the enhancement of silver triangle nanoparticles, we chose the commonly used silver spherical nanoparticles as a comparison. We used the finite difference time domain method to model and calculate the local electric field and extinction efficiency for the two shapes of silver nanoparticles. The simulation results show that the local electric field intensity of triangular silver nanoparticles is 10 times that of spherical silver nanoparticles, and the extinction efficiency is 4 times that of spherical silver nanoparticles. In the experiment, a U-shaped LSPR fiber sensor with spherical and triangular silver nanoparticles was fabricated. The former has a refractive index sensitivity of 342.7 nm/RIU and the latter has a sensitivity of 1116.8 nm/RIU. Even if there is temperature interference during the detection process, the detection result will not produce a large error.