Conference Agenda

Plasmonic nanostructures integrated optical fiber platforms have emerged as powerful tools for localized light–matter interaction, enabling applications in sensing, imaging, and photothermal therapy. In particular, combining plasmonic heating and optical sensing on a single fiber tip enables localized photothermal actuation and in situ molecular detection. Most existing fiber probes are designed for a single function or use a single excitation wavelength across different functionalities, which can limit their effectiveness in multifunctional applications. In this work, we present a multifunctional plasmonic fiber probe that enables spectral multiplexing of plasmonic heating and surface-enhanced Raman spectroscopy (SERS). The probe is realized by integrating gold nanoislands (AuNIs) on the flat facet of an optical fiber using a solid-state dewetting process. The morphology of the AuNIs is controlled by adjusting the initial gold film thickness (5–10 nm), allowing tuning of the optical response and photothermal behavior. The probe operates in a dual-functional mode, with plasmonic heating at 473 and 633 nm and SERS sensing at 785 nm. Temperature gradients of 5–8 °C are achieved using 20 mW input power, with localized heating and a transient response time of ~650 ms. These results demonstrate a compact and multifunctional fiber platform for integrated biomedical applications.

Prism-coupled surface plasmon resonance (SPR) sensing is commonly implemented in the Kretschmann or Otto geometries, each with different advantages in simplicity and tunability. Here, we investigate the hybrid Kretschmann-Otto (KO) configuration, in which the dielectric thickness acts as an additional control parameter and enables coupled surface plasmons. Compared with the standard Kretschmann geometry, KO provides access to dielectric-thickness-dependent information and distinct sensitivity to the properties of each metal, which can favor asymmetric metal structures, while maintaining a broader working range than the pure Otto scheme. Reflectance maps are presented using the general model, highlighting KO as a versatile platform for tunable SPR sensing.

The energy transfer effect (or optical switch) between propagating diffraction orders (the 0th and -1st orders) in a deep metal grating has shown that two diffraction orders can exchange energy during an angular or spectral sweep via plasmonic mode coupling (LRSP). This phenomenon is explained by a strong, nearly lossless interaction between plasmonic modes (SPR) excited by a TM-polarised incident wave, which can only occur in deep metallic gratings. This effect is being investigated for the development of new plasmonic sensors (for the detection of gases and biological species) whose performance may exceed current SPR sensors state of the art, with detection limits (LOD) below 10⁻⁷ RIU.

We propose a dielectric multilayer platform with chiral gold metasurfaces enabling polarization-selective diffraction of Bloch Surface Waves (BSWs) with an imparted geometrical phase profile. Well-defined Orbital Angular Momentum (OAM) generation occurs when BSW are coupled, from an external laser beam. The metasurface chirality provides polarization selectivity, allowing at least 74% out-coupling into free space with a desired circular polarization. This approach opens new opportunities for generating free-space OAM single photons as an alternative to recently proposed plasmonic structures, particularly when single emitters are grafted on the device surface.

The effective medium concept enables advanced optical functionalities but typically relies on complex metamaterial or multilayer architectures with high-index-contrast interfaces, which introduce optical losses and fabrication complexity. Grey-scale micro- and nanofabrication provides an alternative approach by enabling continuous modulation of structural geometry and refractive index distribution, allowing quasi-continuous effective media without discrete meta-atoms or multilayer stacks. This approach reduces interface-induced optical losses and expands the design space for low-loss gradient-index components and three-dimensional photonic structures compatible with scalable fabrication.

Precise inspection of functional surfaces is essential in science and industry. Although, surface measurement is well established using optical methods such as confocal microscopy and white light interferometry (WLI), their application to hard-to-access internal surfaces such as tight boreholes and small surface features remains challenging. Miniaturized fiber-based WLI could be a promising solution for inspecting such surfaces. In this work we show how to print microlenses on modified fiber tips for application in fiber based white light interferometry and discuss challenges related to this approach.