The integration of plasmonic structures with step-index optical fibers is gaining traction for both fundamental research and practical applications. However, the challenge lies in dynamically controlling the interaction between guided light fields and plasmonic resonances, as multimode fiber (MMF) propagation introduces turbidity. This limitation has historically restricted the potential of nanostructured fiber optics.

By leveraging the full spectrum of guided modes, we demonstrate a spatiotemporal control approach that enhances plasmonic resonances at the fiber tip. Using dynamic phase modulation, we structure the plasmonic response on both the plasmonic facet and its Fourier plane, achieving spatially selective field enhancement and direct tuning of the probe’s work point in the dispersion diagram. This breakthrough paves the way for next-generation biomedical imaging and sensing, particularly in holographic endoscopic applications, by integrating advanced plasmonic sensing and light manipulation capabilities.

Keywords: plasmonic multimode fibers, step-index optical fibers, dynamic phase modulation, holographic endoscopy, nanostructured fiber optics, guided modes, plasmonic resonance control, biomedical imaging, fiber-optic sensing, Fourier plane modulation.