Mid-infrared (MIR) imaging plays a pivotal role in chemical sensing, biomedicine, and material analysis, yet its further development is fundamentally constrained by limited room-temperature sensitivity and the lack of efficient multidimensional light-field control. In recent years, frequency upconversion imaging has emerged as a rapidly advancing approach that translates MIR signals to the visible or near-infrared domain, enabling high-sensitivity detection with mature, low-noise photonic platforms. More importantly, by engineering the pump field in nonlinear frequency conversion processes, a multidimensional imaging framework has been established, enabling indirect, all-optical encoding and retrieval of multiple degrees of freedom—including amplitude, phase, spectrum, time, and polarization—of MIR light fields. This paradigm shifts complex light-field manipulation from the MIR to technologically mature short-wavelength regimes, overcoming intrinsic limitations of conventional approaches. In this review, we systematically summarize the principles, architectures, and representative methodologies of MIR upconversion multidimensional imaging, and outline future directions toward high-sensitivity, high-dimensional, and integrated imaging systems, with implications extending to broader photonic and information processing domains.
Coordinated control of coupled heat and charge transport is fundamental to advanced thermoelectric energy conversion and management. Existing thermoelectric metamaterials are largely limited to static or steady-state functionalities. While spatiotemporal modulation has enabled dynamic regulation of single diffusion fields, extending such control to coupled thermoelectric systems remains challenging due to the intrinsic coupling via the Seebeck and Peltier effects and the vastly different thermal and electrical timescales. A unified theoretical framework for designing physically consistent, dynamically reconfigurable thermoelectric devices under transient conditions is lacking. Here, we establish a time-dependent transformation theory for coupled thermoelectric fields. We prove that the governing equations retain form invariance under coordinate transformations even when material parameters vary in space and time, and derive transformation rules for thermal conductivity, electrical conductivity, heat capacity, and the Seebeck coefficient. This enables the systematic design of dynamic thermoelectric functionalities through spacetime-dependent coordinate mappings. We numerically demonstrate three representative functionalities—cloaking, concentration, and rotation—in which heat flux and electric current are manipulated simultaneously without disturbing external fields. Furthermore, we design a time-adjustable thermoelectric cloak-concentrator by introducing a time-dependent virtual radius. For experimental realization, we propose a rotatable checkerboard structure based on effective-medium theory that exhibits periodic switching between cloaking and concentrating modes using conventional metals. This work provides a unified framework for designing dynamically reconfigurable thermoelectric devices, transcending the functionality-fixed limitation of conventional metamaterials. The theory is generalizable to other coupled diffusion processes, opening avenues for adaptive energy routing, intelligent thermal management, and spatiotemporal information processing.
We conceive low-melting-point metal derived superconductors (LMDSs) as a unified paradigm that enables the rapid fabrication of superconducting materials under near-ambient conditions through introducing low-melting-point metals (LMs) as dynamic metallic reaction media. In this framework, LMs serve as solvents, dopant reservoirs, interfacial mediators, and structural templates that lower the barrier to forming superconducting-relevant material states. This paradigm integrates LM-enabled pathways for producing bulk alloys, printed films, two-dimensional confined phases, interconnect geometries, and nanodroplets. Their liquid-state processability enables near-room-temperature patterning, reconfiguration, and compositional control, whereas superconducting functionality is established in cooled LM-derived states such as solidified alloys, doped films, amorphous/glassy phases, nanoconfined structures, and interfacially reconstructed layers, of which only solid-state forms have been reported to superconduct so far. We further outline a data-driven LM materials genome that unifies composition, structure, ground-state quantities, interaction parameters, and macroscopic properties to accelerate predictive modeling and inverse design of LMDS. Beyond processing advantages, LMs provide an experimental platform for examining superconductivity in amorphous, nanoconfined, and dynamically disordered states and for revisiting the long-standing question of whether true superconductivity can exist in the liquid state. This perspective positions LMs as a fertile and energy-efficient route toward reconfigurable and potentially transformative superconducting technologies.
Ferroelectric materials, distinguished by their unique spontaneous and electrically switchable polarization, have emerged as a transformative platform for dynamically regulating various catalytic processes. The rational design and engineering of ferroelectric domain configurations offer an effective strategy to tailor activity and selectivity of catalyst. This review comprehensively elucidates the fundamental mechanisms by which ferroelectric domains and domain walls manipulate key catalytic processes, including surface adsorption, charge carrier dynamics, and reaction pathways. Recent advances in domain engineering of representative ferroelectric catalytic materials (e.g., perovskite oxides and two-dimensional materials) are summarized. Finally, current challenges and future directions in this field are outlined, highlighting the potential of ferroelectric nanomaterials for next-generation efficient and smart catalytic systems.
Nanowire (NW) photodetectors have emerged as a prominent group of optoelectronic materials that have been extensively researched over the last two decades. They belong to the one-dimensional nanostructures and operate in the regime of wave optics because the diameter of the NW is smaller than the wavelength of visible (VIS) light. Under these conditions, the absorption and reflection coefficients can be tuned by manipulating the NW geometry, selecting specific optical modes. The available literature is abundant in the technology development and properties of this new generation of materials, particularly in the context of their usefulness in advancing photodetectors. However, so far, no attempt has been made to determine their place in the broad group of optical radiation photodetectors. The present work addresses this challenge. To begin with, the basic techniques of NW growth are briefly presented, and the fundamental properties and their impact on the photodetector's performance are described. Then, the most important types of NW photodetectors are discussed. The final part of the paper analyses the NW photodetectors' performance against a broad family of VIS and infrared range detectors (including standard commercial detectors and new generation devices—with organic materials, perovskite, two-dimensional materials, and colloidal quantum dots). This analysis indicates the relatively immature fabrication technology of NW detectors compared to alternative new-generation ones, as evidenced by the large scatter in their performance. Some of the published results indicate the NW detectors' performance overestimation.
Neurodegenerative diseases (NDs) and brain tumors constitute two of the most devastating classes of brain disorders, imposing severe and growing burdens on global public health. Fluorescence lifetime imaging microscopy (FLIM) represents a powerful, environment-sensitive analytical tool that enables quantitative interrogation of molecular excited-state decay dynamics, independent of fluorophore concentration. This technique offers unprecedented insights into diverse biological processes, including metabolic reprogramming, protein–protein interactions, and intracellular microenvironmental dynamics, thereby providing a unique mechanistic window into the pathogenesis and early diagnosis of brain diseases. This review provides a comprehensive synthesis of state-of-the-art applications of FLIM in neuropathological research. We first introduce the fundamental principles and major detection modalities of FLIM. We then highlight key advances in applying FLIM to the study of representative brain diseases, with a focus on probing pathological protein aggregation in NDs and delineating tumor margins in brain malignancies. Finally, we critically evaluate current limitations and outline promising future directions to advance FLIM-based technologies toward clinical translation in brain health care.
Conjugated fullerene C60 networks, formed through inter-cage covalent bonding, constitute a versatile carbon platform in which bonding configuration, topology, and dimensionality can be engineered to realize a broad spectrum of multifunctional properties. This review surveys recent progress in two-dimensional covalently bonded, conjugated C60 networks, with an emphasis on synthetic strategies that enable structurally well-defined phases. We establish a synthesis–structure–property framework that links synthetic routes to inter-cage bonding motifs, network topology, and the resulting electronic, mechanical, and thermal transport responses. Beyond summarizing key advances, we critically assess the origins of the substantial scatter in reported properties, tracing it to methodological variations in simulations, particularly the choice of electronic-structure approximations and interatomic potentials as well as the limited availability of reliable experimental data. On this basis, we identify transferable structure–property relationships to guide future materials design. Outstanding challenges are discussed, including precise control over bonding topology, fabrication of well-defined specimens for reproducible and orientation-dependent measurements, and the establishment of quantitative experimental benchmarks. Finally, we outline prospective pathways toward property optimization and validation in device-relevant contexts.
Artificial vision systems conventionally segregate sensing, memory, processing, and display into discrete modules, incurring latency, energy penalties, and architectural complexity. Here, we report a miniaturized synaptic quantum-dot light-emitting diode that monolithically integrates optical sensing, charge-storage memory, and visible emission. Featuring a dual-spectrum-sensitive hole transport layer responsive to ultraviolet (UV) and near-infrared (NIR) light, the device achieves wavelength-gated synaptic plasticity. UV stimuli generate minute-scale electroluminescent afterimages via deep-level hole trapping, while NIR pulses enable millisecond-scale relaxation. This spectral asymmetry establishes distinct “write” and “develop/erase” pathways, facilitating privacy-preserving imaging without external circuitry. Furthermore, the device exhibits real-time motion trajectory display with 98.8% direction recognition accuracy via neural network validation and hardware-level adaptive noise filtering that suppresses random spikes while preserving correlated signals. By transforming the emissive layer into an on-device processing element, this architecture removes the need for separate sensor, processor, and display components, offering a compact platform for intelligent vision systems operating beyond the visible spectrum.
Negative capacitance field-effect transistors offer a promising route to overcome the subthreshold swing limit of 60 mV/dec at 300 K in conventional complementary metal–oxide–semiconductor technology, potentially reducing power consumption without sacrificing performance. This review provides a comprehensive analysis of the negative capacitance (NC) effect in ferroelectric materials and its impact on next-generation electronic devices. We first outline the history and key properties of ferroelectric materials and their role in modern technology, with emphasis on the NC concept, major theoretical frameworks for NC, and state-of-the-art measurement techniques. We then summarize NC behavior across representative material systems, including perovskite, fluorite, and wurtzite ferroelectrics, and discuss key factors that influence NC and its device applications. Overall, this article provides an up-to-date overview of ferroelectric-based NC and its potential for low-power, high-performance electronics.
Liquid crystals (LCs), due to their intrinsic optical anisotropy and strong response to external stimuli, have emerged as a critical bridge between classical optics and quantum photonics. Initially recognized for their transformative impact on display technologies, LCs have garnered increasing attention in recent years within the fields of nonlinear optics (NLO) and quantum optics, driven by their advantages such as electrically tunable birefringence, reconfigurable molecular alignment, and compatibility with compact photonic architectures. This review provides a comprehensive overview of the latest advancements in LC-enabled linear, nonlinear, and quantum optical systems. We begin by discussing the fundamental optical properties and phase states of LCs. Building upon this, we focus on the emerging field of ferroelectric nematic LCs (FNLCs), which, owing to their spontaneous polarization and unique molecular alignment control, demonstrate significantly enhanced second-order nonlinear effects. Helical derivatives of FNLCs further enhance polarization control, giving rise to new concepts in nonlinear geometric phase. Additionally, this paper highlights the applications of FNLCs in quantum photonics, including entangled photon generation and polarization state manipulation. These innovations overcome the limitations of time-reversal symmetry inherent in traditional systems, offering promising opportunities for unidirectional quantum communication, secure quantum networks, and high-fidelity quantum state manipulation. Finally, we discuss the challenges currently facing this field and explore future prospects for FNLCs in interdisciplinary domains such as linear photonics, NLO, and quantum engineering.
Entanglement-based quantum key distribution (e-QKD) is a cornerstone of quantum-secure communication, offering advantages in device-independent security, compatibility with quantum networks, and resilience to specific attacks. While the probabilistic nature of entangled photon generation has slowed down experimental adoption compared to prepare-and-measure approaches, deterministic solid-state emitters—particularly epitaxial quantum dots (QDs)—have recently emerged as promising candidates for scalable, high-rate implementations. In this review, we survey the main e-QKD protocols along with their practical requirements and assess current technologies for entangled photon pair generation. We place particular emphasis on the state of the art in QD-based entangled photon sources, analyzing design strategies and performance metrics that directly impact secure key generation. Recent experimental advances demonstrating entanglement distribution and e-QKD with QDs over both fiber and free-space channels are discussed in detail. We conclude with an outlook on remaining challenges in source engineering, transmission capacity, and system integration, highlighting the potential of QDs to enable next-generation quantum communication technologies.
Terahertz (THz) radiation, which occupies a crucial region between electronics and photonics, has become a transformative tool in strong-field physics, ultrafast spectroscopy, and materials control. This review offers a comprehensive survey of cutting-edge advances in THz generation via optical frequency downconversion and its emerging applications. We delve into the principles and significant progress underlying various THz sources, including optical rectification in lithium niobate and organic crystals, optical different frequency generation, intense laser-induced electron radiation, spintronic THz emission, and quantum cascade lasers (QCLs). The review also highlights the profound impact of these intense THz sources in material manipulation, such as polarization control, phonon polariton excitation, and nonlinear phononics, and in revolutionizing electron dynamics through compact acceleration. Furthermore, we cover advances in THz QCL frequency combs and their role in high-precision dual-comb spectroscopy. Finally, we discuss remaining challenges and future directions, offering a roadmap for the development of next-generation high-field THz technologies and their applications in fundamental research and critical applications.
Three-dimensional (3D) bioprinting technology is used to fabricate complex 3D structures using various biological molecules and biomaterials. The numerous 3D printing technologies are divided into four categories: extrusion-based bioprinting, laser-assisted bioprinting, stereolithography, and inkjet-based bioprinting. The sources used for 3D bioprinting include natural polymers (gelatin, agarose, collagen, fibrin, and alginate), synthetic polymers [polycaprolactone, poly (lactic-co-glycolic acid), and polyvinylpyrrolidone], and living materials (mammalian cells, plant cells, and microorganisms). Living materials provide environmental parameters and facilitate the natural synthesis of complex biomolecules with biofunctions. This review provides a systematic overview of recent advancements in the development of 3D bioprinting technology, emphasizing the use of living materials as bioinks, particularly mammalian cells, plant cells, microorganisms, and microalgae. We briefly discuss the promising applications of using living materials for 3D printing in the medical field, robotics industry, and environmental protection. Furthermore, limitations and current challenges for standardization of living materials and future prospects of using 3D bioprinting technology are also reviewed. This review also presents the potential future applications of 3D bioprinting technology using living materials.
Catastrophic optical damage (COD) remains a defining reliability challenge in high-power edge-emitting diode lasers, continuing to limit power density and operational lifetimes despite decades of progress. COD is irreversible and occurs preferentially, but not exclusively, at high-power densities. The understanding of the physical mechanisms leading to the COD constitutes a step forward for making more power devices able to operate safely for thousands hours. We provide a review of COD in devices made from various material systems (GaAs, GaN, and InP), and the explanations of the various microscopic processes related to its occurrence. COD is launched by the formation of local hot spots, preferentially, but not only, at the light exit aperture of devices. The COD is described as a complex non-linear effect involving optical, thermal, mechanical, and electrical phenomena. The properties of the materials sensitive to the degradation and the experimental techniques for identifying the degradation fingerprint are also treated. A critical insight is the central role of the facet region, where optical loading, native oxides, and defect structures converge to initiate the failure. Recent mitigation strategies have significantly raised COD power thresholds. This review provides the recent developments underscoring a multifaceted approach combining surface engineering, passivation, and device design to suppress COD. Nevertheless, it is to be expected that in the quest to achieve ever lower costs in cents/W of emission power, the presence COD will remain a feature of future generations of devices, requiring continued close attention.
Semiconductor quantum dots represent one of the most promising classes of deterministic single-photon sources for emerging quantum technologies. These nanostructures offer several key advantages, including extremely low multi-photon emission probabilities, high photon fluxes, and the potential for large-scale production using well-established semiconductor fabrication techniques. Their operation has been thoroughly demonstrated in the visible and near-infrared spectral regions, and considerable effort is now focused on adapting these devices to emit within the telecommunication wavelength bands. Achieving this compatibility is an essential milestone toward realizing fiber-integrated quantum communication networks. This review provides an overview of various methods for the growth of quantum dots, alongside strategies implemented at the device level to improve their optical performance across a range of emission wavelengths. A particular emphasis is placed on work conducted by the Chair of Technische Physik at the University of Würzburg, but we do present our work in the broader context of other approaches. We examine major advancements in epitaxial growth techniques on indium phosphide (InP) substrates, as well as innovations in mechanical strain tuning using piezoelectric elements, and photonic integration via micropillar cavities and circular Bragg grating structures. Furthermore, we discuss recent progress in enhancing photon indistinguishability within the telecom C-band using advanced excitation schemes and cavity quantum electrodynamics, including efforts in deterministic cavity positioning. Collectively, these developments underscore the strong potential of quantum dot-based devices as foundational components for scalable, high-performance quantum photonic systems.
Recent advances in semiconductor lasers have greatly expanded their scope of applications. Initially limited to optical communications, these lasers now compete effectively with fiber and solid-state lasers across diverse advanced fields, including sensing, microwave photonics, LiDAR, frequency comb generation, and quantum computing. These expanded capabilities are driven by continuous improvement in their stability, output power, reliability, and efficiency. Moreover, semiconductor lasers serve as a versatile platform for investigating emerging physical phenomena in fields like non-Hermitian and topological physics. In this review, we discuss the key theoretical approaches used to model complex semiconductor laser systems, focusing on both time- and frequency-domain approaches. We first introduce the fundamental equations underlying each approach and highlight essential terms accounting for cavity dispersion and nonlinear effects. We then extend these models to address complex and coupled cavities and detail their numerical implementations. Finally, we illustrate the practical applications of these models by exploring narrow-linewidth operation in self-injection locked lasers as well as passive and active mode-locking dynamics.
PtBi2 is a polymorphic material that can crystallize in different (meta-)stable forms. Historically, it is best known for its pyrite (cubic) form, which displays an extremely large, nonsaturating magnetoresistance. In the last decade, a new crystal form of PtBi2 has attracted considerable attention: trigonal PtBi2. It crystallizes in the space group P31m and is a van der Waals layered material. Density functional theory predicts it to be a topological Weyl semimetal, with symmetry-protected topological band crossings lying near the Fermi energy. This particular electronic band structure leads to the formation of topological surface states known as Fermi arcs, which have been observed by spectroscopic techniques. In addition to its topological properties, trigonal PtBi2 has been found to undergo a superconducting transition at low temperatures, as evidenced by transport experiments as well as with spectroscopic methods (angle-resolved photoelectron spectroscopy and scanning tunneling microscopy). Various strategies have also been explored to enhance the superconductivity in PtBi2, including point contact, doping, and pressure-induced methods, which are also discussed in this review. This review begins with an overview of the synthesis, crystal symmetry, and electronic structure of trigonal PtBi2. It then provides a comprehensive summary and analysis of recent advances in understanding its superconductivity and topological properties. Finally, the review discusses the potential applications of this material, for instance, in uncovering and engineering exotic quantum states, as well as its promises for realizing unconventional pairing mechanisms and topological superconducting phases.
Polarization-sensitive photodetection, capable of simultaneously capturing the essential optical parameters of light intensity, wavelength, and polarization state, has demonstrated remarkable potential in fields such as remote sensing, biomedical diagnostics, and neuromorphic perception. Two-dimensional (2D) semiconductor heterostructures, owing to their well-defined interfaces and tunable electronic properties, can precisely control the separation and transport behavior of photogenerated carriers during the photoelectric conversion. This capability significantly enhances the performance of polarization-sensitive photodetectors. Nevertheless, achieving higher polarization ratios remains a critical challenge for the majority of 2D heterostructure-based devices. This review provides a systematic overview of recent progress in 2D semiconductor heterostructure polarization photodetectors. The review begins by outlining the working mechanisms of 2D heterostructure photodetectors constructed from representative 2D semiconductors, followed by an overview of their key performance metrics, including responsivity, detectivity, and polarization ratio. Special attention is given to strategies for improving polarization sensitivity, such as crystallographic orientation design, application of external electric fields, and integration of ferroelectric polarization fields. In parallel, the review explores emerging applications in imaging and recognition, digital signal processing, and optical communication. To conclude, this review outlines the key technical challenges, including scalable material synthesis, array fabrication, and system-level integration, and discusses future opportunities in interface engineering for controllable stacking, array-level optimization, multifunctional integration, and application-oriented device design.
Exceptional points (EPs), representing non-Hermitian singularities where eigenvalues and eigenvectors coalesce, have emerged as an intriguing concept in modern physics. Their unique topological and asymmetric responses have enabled new pathways for controlling wave propagation, sensing, and signal processing. Among the diverse platforms, plasmonic systems have proven especially attractive, as their inherent loss, strong dispersion, and tunable resonances and coupling can be utilized to tailor EPs at the subwavelength scale. In this review, we provide a comprehensive overview of recent advances at the intersection of EP physics and plasmonics. We first introduce the mathematical and physical foundations of EPs in non-Hermitian systems. We then discuss key experimental and theoretical developments in plasmonic EPs, including polarization manipulation, asymmetric wavefront control, mode conversion, and enhanced sensitivity. Particular attention is given to strategies that exploit symmetry breaking, loss engineering, and geometric phases to realize novel and robust EP-driven functionalities. Finally, we discuss emerging trends, such as the use of EP pairs for full vectorial control and the integration of non-Hermitian plasmonic structures with tunable, active, and even nonreciprocal thermal emission. By reframing loss as a design resource and leveraging the Riemann-surface geometry of non-Hermitian spectra, plasmonic EPs offer a new route to compact, robust, and programmable nanophotonic devices.
