Surface plasmon enhanced up-conversion from NaYF4:Yb/Er/Gd nano-rods.

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Up-conversion (UC) emission in rare-earth doped nanomaterials is crucial for various photonic applications.
• Controlling and enhancing UC emission intensity and spectral characteristics remains a key challenge.
• Surface plasmon resonance (SPR) in metallic nanostructures offers a pathway to manipulate light-matter interactions.

Purpose of the Study:

• To investigate the effect of surface plasmons from gold nanoparticle arrays (AuNPAs) on the up-conversion emission of Yb(3+)-Er(3+)-Gd(3+) co-doped sodium yttrium fluoride (NaYF4) nanorods.
• To understand how the geometric characteristics of AuNPAs influence the spectral properties and intensity of the UC emission.
• To explore the potential of plasmonic enhancement for optimizing UC nanophosphors.

Main Methods:

• Fabrication of two-dimensional AuNPAs with controlled periodicity.
• Synthesis of Yb(3+)-Er(3+)-Gd(3+) co-doped NaYF4 nanorods.
• Characterization of UC emission spectra and lifetimes under 980 nm diode laser excitation.
• Utilizing finite difference time domain (FDTD) calculations for theoretical analysis.

Main Results:

• Significant enhancement of the red emission (660 nm) from NaYF4:Yb/Er/Gd nanorods was observed due to interaction with AuNPAs.
• The geometric properties of AuNPAs tuned the SPR position and near-field strengths, impacting emission.
• Normalized red to green emission intensity reached 1.4 compared to a reference without nanostructures.
• Emission lifetimes decreased with decreasing AuNPA periodicity, showing up to a 6% reduction.

Conclusions:

• Grating-coupled surface plasmons in AuNPAs effectively enhance the red up-conversion emission of NaYF4:Yb/Er/Gd nanorods.
• Plasmonic interactions provide a tunable mechanism to modify the spectral characteristics and intensity of UC emission.
• The findings demonstrate a promising strategy for developing advanced luminescent nanomaterials with tailored optical properties.