The scientific effort to control the interaction between light and matter has grown exponentially in the last 2 decades. This growth has been aided by the development of scientific and technological tools enabling the manipulation of light at deeply sub‐wavelength scales, unlocking a large variety of novel phenomena spanning traditionally distant research areas. Here, the role of chirality in light–matter interactions is reviewed by providing a broad overview of its properties, materials, and applications. A perspective on future developments is highlighted, including the growing role of machine learning in designing advanced chiroptical materials to enhance and control light–matter interactions across several scales.

Sensitivity and specificity in biosensing platforms remain key aspects to enable an effective technological transfer. Considerable efforts have been made to design sensing platforms capable of controlling light–matter interaction at the nanoscale. Here, we numerically investigated how a 3D out-of-plane chiral plasmonic metasurface can be used as a key element in a sensing platform, by exploiting the variation in the plasmonic and lattice modes as a function of the refractive index of the surrounding medium. The results indicate that chiral metasurfaces can be used to perform sensing, by detecting the refractive index change with a maximum sensitivity of 761 nm/RIU. The metasurface properties can be suitably designed to maximize the optical response in terms of the shift, modulated by the refractive index of the analyte molecules. Such studies can pave the way for engineering and fabricating highly selective and specific chiral metasurface-based refractive index sensing platforms.

Counterfeiting poses an ever‐growing challenge, driving the need for innovative anti‐counterfeiting strategies and technologies. Many solutions focus on tags characterized by optical features that are camouflaged to the human eye, thus discouraging scammers. In this paper, a QR code is printed using a commercial printer on a thin plastic foil previously coated by a specific nanocavity consisting of a metal‐insulator‐metal‐insulator (MIMI) multilayer, that possesses unique features in terms of light transmission and reflection, due to its specific design. A thin layer of polymer dispersed liquid crystals (PDLC), is fabricated to camouflage the QR code that becomes, then, readable only under specific thermal conditions. Two anti‐counterfeiting tags were fabricated, each using a distinct nematic liquid crystal (NLC) with its own nematic‐isotropic transition temperature. The combination of the unique optical properties of NLCs and optical nanocavities results in the creation of a new type of tags showing two different encoding levels. Stability tests such as immersion in water, bending test, and prolonged heating have been performed ensuring the long‐term stability of the tags. The realized two security‐level anti‐counterfeiting tags are cost‐effective, straightforward to manufacture and, thanks to their flexibility, can be easily integrated into packaging and products.

Efficient photothermal conversion and localized thermal field modulation are powerful design axes for next‐generation energy, electronic, and biomedical materials. Conventional photothermal platforms typically rely on opaque broadband absorbers, enforcing a fundamental trade‐off precluding simultaneous optical transparency and high thermal performance. Here, we report a semi‐transparent Fano nano‐cavity resonator, fabricated via lithography‐free deposition, that overcomes this limitation by operating under a critically coupled, resonant interaction regime. By harnessing asymmetric Fano interference between a continuous lossy background and a discrete cavity mode, the resonator suppresses reflection to achieve a zero‐reflectance () state. Under this coupling condition, the system reaches a balanced 50%–50% optical transmission absorption, respectively. Under continuous‐wave laser excitation, this optimal energy partition drives extreme, spatially confined temperature rises exceeding 500 within seconds, with an internal photothermal efficiency of 50%. Its functional versatility is demonstrated across diverse applications, including rapid phase‐transition defrosting and localized biothermal tissue cauterization, along with the proof of concept of an optical scalpel.

Metasurfaces have been extensively engineered to produce a wide range of optical phenomena, allowing unprecedented control over the propagation of light. However, they are generally designed as single-purpose devices without a modifiable post-fabrication optical response, which can be a limitation to real-world applications. In this work, we report a nanostructured planar fused silica metalens permeated with a nematic liquid crystal (NLC) and gold nanoparticle solution. The physical properties of embedded NLCs can be manipulated with the application of external stimuli, enabling reconfigurable optical metasurfaces. We report all-optical, dynamic control of the metalens optical response resulting from thermo-plasmonic induced changes of the NLC solution associated with the nematic-isotropic phase transition. A continuous and reversible tuning of the metalens focal length is experimentally demonstrated, with a variation of 80 um (0.16% of the 5 cm nominal focal length) along the optical axis. This is achieved without direct mechanical or electrical manipulation of the device. The reconfigurable properties are compared with corroborating numerical simulations of the focal length shift and exhibit close correspondence.

Using ultrasound-assisted extraction, we obtained a chlorophyll-rich extract from Opuntia ficus-indica cladodes (OFI) characterized through thin-layer chromatography (TLC), Fourier-transform infrared spectroscopy (FTIR), and spectrophotometric absorption analysis. The dye exhibited a strong fluorescence response in the visible range (400–800 nm) with a pronounced red emission when excited with a UV source. Antioxidant ability was evaluated via DPPH assay, showing an IC₅₀ of 185 µg/mL, highlighting its potential for reactive oxygen species scavenging. The extract was incorporated into polymethyl methacrylate (PMMA), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA), leading to fluorescence intensity enhancements of up to 40 times compared to the dye alone depending on matrix polarity, consistent with aggregation and polarity effects. Stability tests confirmed the dye’s resistance to CO₂ exposure, pH variations, and prolonged storage, positioning it as a viable alternative to synthetic fluorophores. These findings suggest that the OFI extract provides a functionally relevant, bio-derived dye platform promoting the valorization of agricultural by-products in high-value technological applications, highlighting a circular and scalable approach to developing ecofriendly fluorescent materials, aligning with sustainability and green technology goals.