Plasmon-enhanced optical performance in S-bend pedestal-type TeO2–ZnO waveguides doped with Nd3+

We report the fabrication and optical characterization of curved pedestal waveguides based on Nd³⁺ doped TeO₂–ZnO (TZ) thin films, with and without gold nanoparticles (Au NPs), for near-infrared photonic applications at 1064 nm. The waveguides were fabricated using RF sputtering, direct-write photolithography, and reactive ion etching (RIE), and exhibit well-defined S-bend geometries. Scanning electron microscopy (SEM) was employed to verify structural fidelity and confirm the defined waveguide geometry, while atomic force microscopy (AFM) confirmed low surface roughness (Sa = 0.5 ± 0.3 nm), supporting efficient light coupling. Propagation losses of about 1.0 dB/cm were determined for 10 μm S-bend waveguides, whereas smaller widths showed higher losses that reached 6.0 dB/cm. Samples containing Au NPs exhibited an approximate 33 % increase in photoluminescence intensity, attributed to local electric field enhancement effects. The best performance was observed for 2 and 4 μm width S-bend waveguides whose relative gains reached ∼4.0 dB/cm, at 1064 nm, indicating an increase of about 100 % due to Au NPs. However, considering the propagation losses, the internal gain analysis revealed positive values for the 10, 8, and 4 μm wide S-bend waveguides with and without Au NPs. These findings confirm the potential of Nd³⁺ TZ S-bend waveguides with plasmonic enhancement for integrated near-infrared (NIR) amplifiers and light sources.