Optical fiber-based platforms are increasingly explored as compact, minimally invasive tools for integrated photonic functionalities in biomedical applications. Among these, the combination of plasmonic heating and optical sensing on a single fiber tip offers compelling opportunities for localized photothermal actuation and in situ molecular detection. This work presents a multifunctional plasmonic fiber probe that enables spectral multiplexing of thermo-plasmonic heating and surface-enhanced Raman spectroscopy (SERS). This dual capability is achieved by integrating gold nanoislands (AuNIs) onto the flat facet of a multimode optical fiber using a solid-state dewetting process—a straightforward and scalable fabrication method that avoids the complexity of lithographic techniques. The morphology of the AuNIs is characterized in terms of its modulation of optical extinction, photothermal response, and electromagnetic field enhancement across the visible and near-infrared spectrum. In particular, efficient, wavelength-dependent heating under visible light and strong SERS signal enhancement under near-infrared excitation are demonstrated, both supported by electromagnetic and thermal simulations. The ability to decouple photothermal stimulation and Raman sensing in a single, fiber-integrated device addresses a current gap in lab-on-fiber technologies, where multifunctional operation is often constrained to a single wavelength.
Kashif et al. (Sun,) studied this question.