Metal nanomaterials have attracted increasing attention due to their outstanding nonlinear optical and photonic properties, making them as potential saturable absorber (SA) candidates for realizing ultrafast photonic devices. In this paper, we demonstrate the generation of mode-locked dual-wavelength pulse trains in an Ag nanoplates (AgNPTs)-based Yb-doped all-fiber laser for the first time to the best of our knowledge. The AgNPTs are synthesized by seed-mediated growth and then integrated into a fiber ferrule by optical deposition, which serve as SA in the ring laser cavity. The plasmonic properties of such nanoplates are measured by absorption spectrophotometry and their nonlinear optical properties are characterized by Z-scan. The measured nonlinear saturable absorption of the AgNPTs-based SA is 6.4%. In our laser, the dual-wavelength synchronous mode-locking is achieved at the center wavelengths of 1031.92 and 1033.24 nm with 3-dB spectral bandwidth of 0.52 and 0.46 nm, respectively, where 293-ps pulse trains with a repetition rate of 11.43 MHz are obtained at the pump power of 350 mW. The results demonstrate that the solution-processed AgNPTs are promising SA candidates for achieving stable and low-cost pulsed laser sources which could be used for spectroscopy and ultrafast photonics.

Noble metal nanostructures provide versatile platforms for light manipulation through localized surface plasmon resonances (LSPRs). Among them, triangular silver nanoplates (AgNPTs) exhibit strong field-enhancement and spectral tunability, yet assembling them reproducibly on solids is challenging. We report a two-step functionalization strategy for constructing ordered AgNPT dimers on silica substrates, combining 3-aminopropyltriethoxysilane (APTES) anchoring with 1,4-butanedithiol bridging. AFM reveals face-to-face dimers with well-defined sub-nanometer gaps. Large-area AFM statistics collected over multiple regions (N = 80 nanoplates per condition) confirm reproducible and selective vertical dimerization. Extinction spectroscopy reveals sequential dielectric and coupling effects: thiol adsorption red-shifts the main resonance from 700 to 780 nm because of increased local refractive index and near-field damping, whereas dimerization partially restores it to ≈750 nm, consistent with plasmon hybridization within rigid ∼0.7 nm molecular gaps, where nonclassical moderation may occur but classical hybridization fully explains the observed shifts. Concomitantly, the extinction intensity doubles, following an exponential growth toward saturation during assembly. Surface-enhanced Raman scattering (SERS) measurements using 4-mercaptobenzoic acid (4-MBA) confirm a fourfold increase in the SERS enhancement factor from monolayer to bilayer, consistent with near-field coupling and hotspot formation at interplate junctions. Quantitative plasmon sensitivity analysis yields comparable results between experiments and finite-difference-time-domain simulations, confirming that the observed spectral shifts arise from near-field coupling and dielectric modulation rather than ensemble effects. This reproducible methodology enables precise tuning of NPT orientation, spacing, and optical response, providing a robust platform for enhanced sensing, SERS, and nanophotonic device engineering.