Dual-parameter control of polarization correlations between excitation and emission in nanowire-cylindrical particle coupled structures

Surface plasmon polaritons in silver nanowires (Ag NWs) enable subwavelength optical confinement but suffer from limited local field enhancement. Coupling Ag NWs with silver nanoparticles (Ag NPs) addresses this limitation by leveraging synergistic resonant effects, yet dynamic polarization control mechanisms remain underexplored. Here, we systematically investigate the polarization-dependent emission from silver nanowire-cylindrical nanoparticle coupled structures via integrated finite-difference time-domain simulations, dipole radiation theory, and experimental validation. Crucially, we reveal a size-governed modulation paradigm: For small nanoparticles, emission polarization is strictly locked to the particle's long axis, acting as a directional dipole antenna independent of incident polarization. For large nanoparticles, emission polarization varies continuously with incident polarization, modulated by particle orientation via a gap-based Fabry–Perot resonator. Mode analysis attributes this dichotomy to competition between the particle's dipole mode and hybridized nanowire-plasmon modes, where nanoparticle size and orientation dictate energy partitioning. Experimental results on polyol-synthesized nanostructures corroborate the simulations. This dual-parameter control strategy establishes a novel pathway for nanoscale polarization manipulation, providing a foundational design principle for advanced photonic devices such as ultracompact polarization detectors and high-sensitivity sensors.