Photonics represents a low-hanging fruit and a highly lucrative industry on the global stage, with applications spanning healthcare and biophotonics, energy and environmental photonics, agriculture and food systems, quantum photonics, telecommunications and data communications, among many other sectors. Despite this breadth of opportunity, the availability of structured biophotonics courses and programs remains limited, largely due to the inherently multidisciplinary nature of the field. Compounding this challenge, many schools, particularly in developing countries, lack adequate science laboratories, especially at the secondary level, thereby depriving learners of the practical exposure necessary to grasp fundamental theoretical concepts meaningfully. These gaps underscore the need for innovative and creative approaches to education and capacity development. Initiatives such as job-shadowing opportunities, outreach activities, summer schools, and diverse forms of online learning are therefore essential in widening access and building foundational skills. Introducing photonics, optics, and biophotonics at the high-school and undergraduate levels would significantly strengthen the talent pipeline, cultivating scarce and highly sought-after skills. Against this backdrop, this paper highlights the importance of targeted strategies that advance biophotonics education and capacity building as a catalyst for sectoral growth.
High-purity semi-insulating silicon carbide (HPSI-SiC) is a high-end substrate for power devices. However, both electrical and optical characterization of threading dislocations (TDs) remains challenging because of its low free-carrier concentration and abundant compensating deep-level defects. Here, we develop an optical technique for the selective identification and electronic characterization of device-relevant TDs with continuously distributed deep-level states. By employing partially etched TDs, TD types can be resolved through laser backscattering from etch-pit morphology, while their electronic activity is assessed via deep-level photoluminescence (PL) from the underlying dislocation lines. Statistical one-to-one structural-electronic correlation reveals that only a small fraction of pure screw-type TDs exhibits broadband deep-level emission, which is attributed to inherent dislocation-core states. These deep-level TDs may potentially form leakage-current pathways through trap-assisted mechanisms. Our work demonstrates a nondestructive PL-active approach for optically identifying deep-level TDs in HPSI-SiC.
Dielectric metasurfaces have emerged as promising candidates for controlling electromagnetic (EM) multipoles, crucial for precise manipulation of associated light-matter interactions, particularly for multifunctionality in photonics technologies spanning across structural scales and the EM spectrum. Each multipole with a given nature (electric-E, magnetic-H) and order (dipole-D, quadrupole-Q) has specific functionality with implications on resonance types (fundamental as well as collective), their coupling and hybridization. By using geometrical dimensions as the primary design parameters, only a few multipoles have been reported to be excited simultaneously. Moreover, an understanding of the relationship among meta-atom Mie resonances, lattice periodicity, and lattice resonances is still lacking. The local field distribution due to spatial hybridization with neighboring meta-atoms is also unknown for finite metasurfaces. We have developed a comprehensive design framework to maximize resonance strength by controlled multipole excitation, overlap, and coupling among different resonance types, including Mie, lattice, Rayleigh anomaly, and local fields in metasurfaces, using numerical simulations. The simultaneous spectral overlap of four multipoles (ED, MD, EQ, and MQ) is demonstrated when the meta-atom height exceeds the excitation wavelength. As periodicity matches both the Mie and Rayleigh anomaly wavelengths, the resulting metasurface resonance attains a high Q factor, attributed to maximum coupling of Mie and lattice resonances. Spatial field hybridization due to the specific arrangement of neighboring meta-atoms, depending on array size, results in asymmetric local field distributions in finite metasurfaces, crucial for real-world implementations. Our findings reveal governing principles linking controlled multipole excitation dynamics, the influence of coupling among different resonance types on the resultant resonances, and local field distributions relevant to multifunctional metasurface photonics and integrated quantum technologies.
Metasurfaces enable subwavelength control of free-space light for applications in sensing, nonlinear optics, and quantum photonics. However, their practical deployment is hindered by two key limitations: a tradeoff between low-Q resonances and weak amplitude contrast, and their predominantly static nature allowing only passive functionalities. These challenges are particularly severe in the mid-infrared (mid-IR), where the scarcity of low-loss materials constrains performance and scalability. Here, we demonstrate actively tunable single-crystalline silicon membrane metasurfaces combining high-Q resonances, strong amplitude contrast, and wafer-scale manufacturability. Our platform achieves record-high measured Q-factors up to 3000 in the mid-IR and supports two dynamic modulation schemes: electro-thermal tuning via Joule heating with  >50% modulation depth at CMOS-compatible voltages and speeds up to 14.5 kHz, and ultrafast all-optical modulation via carrier generation in silicon with nanosecond response times and estimated sub-GHz rates. These results establish silicon membrane metasurfaces as a scalable platform for active mid-IR photonics.
The mid-infrared spectral region holds substantial promise for telecommunications, chemical sensing, and biomedical diagnostics applications. These fields increasingly demand high-resolution, miniaturized, and portable spectrometers. Leveraging recent advances in silicon photonics and computational reconstruction techniques, on-chip spectrometers offer a compact and lightweight solution. This paper presents a distinctive photonic spectrometer prototype based on microcavity-coupled photonic crystal waveguide (MPCW) architecture, operating at the mid-infrared region. The device achieves uniquely defined spectral responses by synergistically integrating non-uniform microcavity resonances with sharp photonics crystal band edges. Benefiting from the slow-light effect, titanium microheaters provide efficient thermal tuning, facilitating further precise spectral response control. The alternating optimization approach for spectral reconstruction eliminates the need for exhaustive parameter searches and substantially alleviates the computational burden. Thus, our MPCW spectrometer can retrieve an unknown spectrum with a resolution of 0.5 nm over a 100 nm bandwidth within several seconds, demonstrating high performance and robustness. Furthermore, the scalable nature of photonic crystal designs permits straightforward adaptation to other wavelength regimes by tailoring the MPCW dimensions.
In nature, photosynthesis is driven by solar light and a large proportion of the visible spectrum is absorbed by the light harvesting complexes (LHCs), which then transfer the energy to the reaction center. Inspired by nature, we implemented a light harvesting energy transfer cascade within biomimetic lipid bilayers of liposomes built with DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine), using membrane-anchored fluorescein, 2-(3,6-dihydroxy-9H-xanthen-9-yl)-5-dodecanamidobenzoic acid (FlC12) as primary absorber and membrane anchored eosin Y, hexadecyl 2-(2,4,5,7-tetrabromo-3,6-dihydroxy-9H-xanthen-9-yl)benzoate (EYC16), as energy acceptor to sensitize oxygen and generate the reactive oxygen species 1O2. Finally, the model substrate nicotinamide adenine dinucleotide (NADH) is oxidized by 1O2 within the compartmentalizing liposome nanoreactors. It was observed that our metal-free LHC system has only a minor effect on the photooxidation rate of NADH when the nanoreactor membrane is functionalized symmetrically. By contrast, asymmetric membrane functionalization of the liposome nanoreactor membranes leads to acceleration by 16% to 27% when using multi-colored light emitting diodes (LED) or simulated solar light, respectively.
A novel method, to our knowledge, for achieving a perfect mirror in the quantum domain is proposed by investigating the optical response of a three-level Λ-type atomic system driven resonantly by three coherent fields in a closed-loop coupling configuration. Owing to phase-controlled quantum interference, the real part of the induced complex permittivity becomes negative with vanishing imaginary part over a finite range of probe detuning. As a consequence, the complex refractive index exhibits a vanishing real part at a specific spectral detuning. Under this condition, the reflectance of the probe beam entering the medium reaches unity with ultimate suppression of transmittance. This leads to the phenomenon of perfect optically induced reflection (OIR). The tunable nature of OIR provides a new route for manipulating light propagation. The present study holds promise for its applications in the field of photonics. To this aim, we have demonstrated a two-port all-optical switching application at low light levels.
Time-resolved measurement of Auger-Meitner decay [Drescher et al., Nature (London) 419, 803 (2002)NATUAS0028-083610.1038/nature01143] marked a milestone in the development of attosecond science. To date, the time constants for the Auger-Meitner decay processes obtained from the time-domain experiments were found to be consistent with the values deduced from conventional energy-domain measurements. One of the main factors limiting the temporal resolution of these studies is the unlocked carrier-envelope-phase (CEP) of the laser pulses used to probe the electronic dynamics triggered by inner-shell photoabsorption. In this Letter, we report time-resolved inner-shell electron spectroscopy of xenon and krypton using attosecond soft x-ray (atto-SXR) pulses centered at 130 eV in combination with CEP-stabilized few-cycle Yb laser pulses. We observed that the N_{4,5}OO Auger electrons from xenon exhibit a clear streaking pattern, but with an unexpected time shift of ∼1.32  fs relative to the 4d photoelectrons. Furthermore, the energy-integrated yield of streaked Auger electrons from xenon exhibits a pronounced minimum at a pump-probe time delay of 4 fs. Neither of these observations can be explained by current streaking theories and both are inconsistent with lifetimes inferred from energy-domain measurements. The M_{4,5}NN Auger electrons from krypton partly overlap in energy with the 3d inner-shell photoelectrons and do not show these anomalous features. This Letter offers new insights into the inner-shell electron dynamics of heavy atoms in the giant dipole resonance region, laying the groundwork for attosecond soft x-ray spectroscopy of molecular systems containing iodine or bromine atoms.
Integrated silicon nitride photonics has emerged as a key enabling technology for quantum technologies. Among the essential devices, beam splitters in the form of integrated directional couplers are widely used in circuits such as Hong-Ou-Mandel (HOM) interferometry. However, the wavelength-dependent nature of these couplers limits their use in experiments involving broadband photons. In this work, we experimentally demonstrate a wavelength-flattened directional coupler on the silicon nitride platform, exhibiting a nearly wavelength-flattened splitting ratio over the measured telecom wavelength range. This integrated photonic circuit is compatible with broadband quantum photonic circuits, including HOM interferometry, and supports the development of integrated single- and photon-pair sources.
Light-responsive hydrogels are attractive materials for mimicking dynamic microstructures in nature, providing platform for tunable devices in photonics, sensing, and biomedicine. However, these systems often suffer from limited spatial resolution and slow response times, restricting their utility in high-speed or high-precision applications. Here, we present a light-responsive hydrogel thin film platform capable of rapid, reconfigurable surface modulation with sub-micron spatial resolution and actuation frequencies up to 2 Hz. The system leverages photoswitchable host-guest interactions to induce reversible contraction-expansion in response to patterned illumination. Dual-wavelength control enables the generation of dynamic, migrating surface features capable of transporting micro-objects in real time. The approach is further extended to free-standing films, demonstrating functionality in laser beam steering. Additionally, surface patterns can be stabilized by drying and erased by humidity, offering a route to rewritable sensor tags.
In recent years, electromagnetically induced transparency (EIT) has attracted extensive attention in the field of photonics. However, such effects typically arise from intricate bright-dark mode design and yield limited quality factors. In this study, an all-dielectric metasurface is experimentally validated to achieve EIT through coupled interactions between symmetry-protected bound states in the continuum (SP-BICs) and intrinsic resonant modes of the metasurface structure. Inheriting the high-Q-factor nature of BICs, the resulting EIT achieves a simulated Q-factor of 3802.61 and demonstrates a significantly strong slow-light effect in the terahertz band, exhibiting a group delay time of 1992.5 ps. This work establishes a new, to our knowledge, approach for EIT implementation via metasurfaces, with promising applications in narrowband filtering and slow-light devices. Moreover, this configuration exhibits superior performance metrics compared to comparable devices in the same category.
Non-Abelian topological insulators, arising from a non-Abelian gauge field, not only link to particle physics and the strong and weak forces of nature, but also create coveted topological phenomena with remarkable properties. Although significant efforts have been made to develop artificial non-Abelian gauge fields, few of them applied to momentum space to realize non-Abelian topological insulators. Here, we propose a scheme to create artificial SU(2) gauge fields in phononic crystals. By implementing this scheme to a non-Abelian Hofstadter model, we overcome the challenge of constructing an analog of the non-Abelian magnetic field in momentum space that opens nontrivial band gaps. We experimentally realize and observe such a non-Abelian topological insulating phase in a phononic crystal. Furthermore, we experimentally investigate the spin rotation and flipping phenomena of non-Abelian topological boundary states along a specific plane of the Bloch sphere, which are linked to the signatures of the underlying non-Abelian gauge field. Our Letter not only opens the door to the realization and characterization of non-Abelian topological insulators, but also provides a reconfigurable platform for exploring non-Abelian physics in a classical system.
Across nature, when systems are driven far from equilibrium, topological defects emerge as universal signatures of how order emerges from disorder. Their formation reflects the interplay between the competing time scales of driving and relaxation that govern their self-organization. Here, we investigate this process in light-responsive azopolymer films that spontaneously self-organize under continuous illumination through photoisomerization and phase separation. By tracking the spatiotemporal evolution of the emerging surface morphology, we identify a characteristic freeze-out timethe intrinsic time scale over which the initially uniform film transitions to an ordered pattern. Correlating this time scale with the defect density reveals a robust positive power-law scaling, where slower ordering near the illumination threshold yields higher defect densities, while stronger excitation accelerates domain formation and produces more coherent, defect-sparse patterns. This behavior is consistent with a self-limited regime in which pattern formation is governed primarily by the material's intrinsic photomechanical relaxation rather than by externally imposed rates. Following the initial pattern formation, we observe a secondary self-annealing regime mediated by transient vortex-antivortex pairing that drives further defect annihilation and surface refinement. These results establish light-driven azopolymers as a versatile and fully optical platform for probing universal kinetic laws of defect evolution, dynamic topological ordering, and nonequilibrium relaxation in soft photonic materials.
Mid-infrared spectroscopy enables biochemical sensing by identifying vibrational molecular fingerprints, but it faces limitations in instrumentation portability and analytical sensitivity. Optical metasurfaces with strong mid-infrared photonic resonances provide an attractive solution towards on-chip spectrometry and sensitive molecular detection, yet their static nature hinders their anticipated impact. Here, we introduce and demonstrate dynamically tunable silicon membrane metasurfaces exhibiting high-Q transmissive resonances in the fingerprint region. By harnessing silicon's thermo-optical properties, we achieve continuous modulation of coupling-induced transparency (CIT) modes that emerge upon the interference of quasi-bound states in the continuum (q-BICs) and surface lattice modes (SLMs). We measure a spectral tuning rate of 0.06 cm-1 K-1 by continuously sweeping the sharp CIT resonances over a 23.5 cm-1 spectral range across a temperature range of 300-700 K. In the current proof‑of‑concept implementation, the dynamic transmission control enables non-contact chemical analysis of polymer films by detecting characteristic absorption bands of polystyrene (1450 and 1492 cm-1) and poly(methyl methacrylate) (1730 cm-1) without requiring conventional spectrometers. When analyte molecules fill the metasurface-generated photonic cavities, we demonstrate vibrational strong coupling between the poly(methyl methacrylate)'s carbonyl band and the CIT mode, manifested in a Rabi splitting of ~43 cm-1. Our results establish a new photonic platform that unites spectral precision, strong field enhancement, and reconfigurability, offering diverse potential for compact mid-infrared spectroscopy, molecular sensing, and programmable polaritonic photonics.
Physical neural networks (PNNs) are neural-like computational frameworks that exploit the intrinsic dynamics of physical media to achieve ultrafast and energy-efficient information processing. However, the complex and strongly-coupled physical nature of PNNs in disordered environments makes them resistant to accurate differentiable modeling. Here, we propose a concept of computational space that empowers the chaotic environment itself with computational capabilities. This space constitutes a large-scale, model-agnostic PNN through distributed intelligent metasurfaces. To enable effective training, we develop a fully-forward learning framework that estimates zeroth-order gradients from in-situ measurable electromagnetic feedback, thereby circumventing the rigorous modeling requirements of conventional backpropagation. In experiments, we construct such computational space that achieves recognition accuracies of 97% for alphabetic characters and 99% for numeric patterns. Furthermore, the space exhibits the functionalities of enhanced focusing under disordered scattering conditions and reliable human position localization. This emerging paradigm of self-evolving physical intelligence holds potential for advancing embodied intelligence, autonomous cyber-physical systems, and next-generation human-machine interaction, marking a fundamental transition from computing the physics to computing with physics.
Programmable integrated photonics aims to replicate the versatility of field-programmable gate arrays in the optical domain. However, scaling these systems has been prevented by the high power consumption and thermal crosstalk of conventional volatile phase shifters. Here we introduce a non-volatile field-programmable photonic gate array, implemented on a hybrid silicon-barium titanate platform, which overcomes the power scaling limitations of previous technologies. Unlike traditional thermo-optic devices that require constant power to maintain a state, our device utilizes ferroelectric domain switching to provide non-volatile memory, allowing optical circuits to be programmed and retained without any holding power or electrical bias. The hexagonal waveguide mesh integrates 58 programmable unit cells and 116 actuators, achieving nanosecond-scale switching speeds of 80 ns while reducing static power consumption to negligible levels (560 nW per π phase shift). To validate this platform, we configured the mesh to perform diverse signal processing functions, including tunable filtering, 4 × 4 linear unitary transformations and optical routing. This work establishes non-volatile ferroelectric silicon photonics as a scalable, heat-free platform essential for the next generation of energy-efficient photonic computing.
Three-dimensional metastructures with nanoscale feature sizes exhibit unique properties compared with structures with larger feature sizes, but are difficult to fabricate. Here we introduce implosion carving (ImpCarv), a method for photopatterning vacancies of complex geometry throughout materials, followed by isotropic shrinkage (>10-fold). ImpCarv works by photoactivating sensitizers to generate reactive oxygen species that cleave a swollen hydrogel at defined points, followed by controlled shrinkage via dehydration. ImpCarv creates three-dimensional metastructures where the refractive index of each point throughout a material can be specified with nanoscale precision via material presence or absence. By leveraging refractive index programmability for precise phase control, we demonstrate an all-optical machine learning device with nanoscale neuron sizes operating at visible wavelengths. ImpCarv may thus support diverse applications in nanophotonics and nanotechnology.
Silicon nanowires have attracted the scientific community's attention due to their exceptional optical properties and potential for device integration. In our previous research, we investigated plasmonic resonance behavior in silicon nanowires to elucidate the physical origin of plasmonic excitations in semiconductor nanostructures and to explore plasmonic responses for potential applications in silicon-based nanophotonic and optoelectronic devices. We directly observed the longitudinal plasmonic resonance and the transverse plasmonic resonance in cylindrical and conical silicon nanowires with diameters of 30-100 nm. In our most recent work, we extended the study to conical-shaped silicon nanowires with quantistic NW tip sizes to further understand the morphological influence on the plasmonic resonances. All our previous findings refer to silicon nanowires enveloped in a silicon oxide shell. It is known that the dielectric shell modulates the local electromagnetic field and resonance conditions. In this paper, we present our investigation of several groups of conical and cylindrical silicon nanowires with varying lengths, without a dielectric shell, suspended in vacuum or deposited on a carbon film. We employed a scanning transmission electron microscope equipped with electron energy-loss spectroscopy. The results indicate that all the investigated SiNW groups exhibit signals with a periodic nature, with a clear, strong dependence of the plasmonic resonance energy on NW length rather than on environmental conditions, and confirm a strong transversal plasmonic resonance signal in all cases. This opens a practical pathway to plasmon engineering in silicon nanowires solely through geometry, simplifying their integration into nanophotonic platforms.
In nature, fruit flies Drosophila have evolved a simple but superb vision system characterised by a three-level synergy: natural compound eyes for panoramic perception, head muscles for continuous tracking in dim conditions, and neural circuits for dynamic scenes. This vision system serves as an ideal model for biomimicry, yet achieving true replication remains challenging, despite significant progress in artificial compound eyes recently. In this study, we present a flexible artificial compound eye camera that adopts such a three-level synergy. An artificial compound eye is constructed by plastic optical fibres and curved microlens arrays for real-time panoramic imaging. Two tethers simulate head muscle movements, achieving a 270° field of view for continuous tracking of weak signals. An artificial intelligence algorithm mimics neural processing, enabling the reconstruction of interactive mixed-reality scenes at rates up to 7000 fps. This unique integration of panoramic sensing, active tracking, and neural-like processing establishes a framework for vision-based metaverse applications and bioinspired wearable technologies.
Silver nanoparticle (AgNP) formation in oligomers (epoxy resins and oligoxypropylenediamine) and epoxy-amine systems based on them were studied in detail using UV-visible spectroscopy, small-angle X-ray scattering, dynamic light scattering, and X-ray diffractometry. The reduction of silver ions in the oligomeric media was carried out at near-room temperatures, which is why it was called "cold". A fundamental difference in the behaviour of Ag+ ions in oligomers, depending on the nature of their terminal groups, has been established, and assumptions have been made about the mechanism of stabilisation of Ag+ ions and nanoparticles based on reduced Ag0 silver atoms. The kinetics of Ag0 nanoparticle formation in epoxy systems has been the subject of investigation, and the influence of the system composition (precursor and solvent concentrations) on this process has been demonstrated. The evolution of Ag0 nanoparticle sizes in epoxy and epoxy-amine systems is discussed, and a hypothesis is put forward about the formation of an oligomeric hydrodynamic shell around these nanoparticles. It is suggested that, depending on the nature of the oligomer's terminal groups, this contributes to either the stabilisation or aggregation of nanoparticles. The present study investigates the influence of temperature on the ratio of Ag+ ion coordination/reduction processes and Ag0 nanoparticle stabilisation/aggregation. The results of this research will be used for the purpose of the targeted regulation of polymer-silver nanocomposite production processes.