Thermally Driven Resonance Tuning in Nanobipyramid Plasmonic Substrates

Abstract

Plasmonic nanoparticles have captivated researchers due to their exceptional optical properties and ability to manipulate light at the nanoscale and have been utilized in various applications. This article explores the shape control of gold nano bipyramid (AuNBP) particles to achieve highly broadband spectral tunability. By tailoring heating profiles, we can adjust the resonance wavelength by over 250 nm. Using in-situ reflection spectroscopy, SEM analysis, and in-situ TEM analysis, we demonstrate that the resonance shift results from changes in the shape and aspect ratio of the anisotropic particles. Heating the nano bipyramid-coated substrates from room temperature to 400°C allows us to effectively tune the resonance wavelength between 750 nm and 530 nm. Additionally, localized heating of the substrates enables the fabrication of substrates with locally modulated resonance wavelengths. This study provides insights into the impact of temperature on the shape change of AuNBP and aids in designing custom-tailored plasmonic substrates for applications in tunable optical filters, biosensing and non-linear signal enhancement.