Deterministic Fabrication of Plasmonic Nanostructures on Optical Nanofibers via Blurred Electron Beam Deposition

This study introduces a novel method for the deterministic fabrication of metallic nanostructures with controlled geometry and composition on suspended, single-mode tapered optical nanofibers (TNFs) using a tailored Blurred Electron Beam Induced Deposition (BEBID) technique. TNFs, owing to their subwavelength diameters and intense evanescent fields, offer a unique platform for enhanced light-matter interactions at the nanoscale. However, their mechanical fragility has thus far hindered the integration of plasmonic structures using conventional high-energy deposition methods. BEBID addresses this limitation by deliberately defocusing the electron beam to reduce local mechanical stress, minimize vibration, and prevent fiber damage during deposition, thereby enabling the one-step growth of platinum nanopillars with sub-20 nm spatial precision and high structural fidelity directly on suspended TNFs. The fabricated structures are characterized using SEM, EDX, and their optical properties are investigated through broadband scattering spectra and polarization-resolved measurements, showing strong agreement with Finite-Difference Time-Domain (FDTD) simulations. Numerical modeling further reveals that ordered arrays of nanopillars can shape and direct the scattered field along the fiber axis, enabling directional emission. This work establishes BEBID as a versatile nanofabrication approach for functional photonic architectures on fragile substrates, with direct applications in quantum photonics, nano-optics, and on-fiber plasmonic sensing.