Photodetectors that integrate two-dimensional (2D) materials with optical waveguides are considered an ideal approach to enhance infrared detection capability and on-chip integration capability and have become a focal point of recent research. These devices benefit not only from the intrinsic optoelectronic properties and flexible hetero-integration of 2D materials but also from a range of engineering strategies that enable precise control over their electronic and optical characteristics. In addition, by combining different types of waveguide structures, the optical field distribution can be effectively tailored, further strengthening light-matter interactions and facilitating the realization of compact, high-performance infrared photodetectors with versatile strategies. This review systematically summarizes the latest progress in waveguide-integrated 2D-material infrared photodetectors, organized primarily by the type of waveguide material and further categorized according to the 2D materials employed. It discusses the advantages of various waveguide structures and 2D materials, the working mechanisms, performance parameters, common device architectures, and many key approaches to improving photodetector performance (e.g., waveguide structure optimization, electrode material and spacing design, gate electrostatic doping, substrate engineering, strain modulation, twist angle control of 2D materials, heterojunction band alignment, etc). Furthermore, a comparative analysis with conventional commercial photodetectors is provided, demonstrating that waveguide-integrated 2D-material infrared photodetectors have already achieved comparable performance in many applications, while certain challenges remain. Finally, the review outlines the key obstacles facing practical implementation and offers perspectives on future research directions. This review examines waveguide-integrated two-dimensional-material infrared photodetectors, focusing on waveguide platforms, material integration, device mechanisms, performance enhancement strategies, and remaining challenges for practical on-chip detection.
Understanding charge dynamics at electrochemical interfaces is essential for establishing the basic mechanisms that underpin the functionality of energy storage devices and ultimately improve their performance, safety and longevity. However, direct, time-resolved access to such information remains challenging due to the complex and convoluted conditions necessary for charge transfer between materials and phases. Here, we report an electroactive fiber-optic device that integrates plasmonic sensing with electrochemical functionality, enabling real-time, multi-scale tracking of interfacial physicochemical changes. Gold-coated tilted fiber Bragg gratings were employed as dual-purpose sensors, simultaneously acting as working electrodes and optical probes of the resulting dynamics. By quantifying spectral response we demonstrate the ability to discriminate charge transfer phenomena across multiple regimes: double-layer formation, ionic and molecular adsorption, faradaic reactions involving both soluble redox species and immobilized thin solid films. By integrating a novel ‘optical-mass’ sensitivity concept, this approach unlocks access to comprehensive operando, real-time monitoring in both aqueous and organic electrolytes. As a first step toward practical deployment, we further demonstrate the feasibility of embedding a surface plasmon resonance tilted fiber Bragg grating sensor within a sealed 18650 Na-ion cell, enabling simultaneous electrochemical and optical interrogation of parasitic redox processes during formation. These results provide a new foundation for non-invasive, mechanistic studies of critical importance to energy storage, electrocatalysis and advanced materials technologies.
Implementing analog reservoir computing (RC) at the edge is fundamentally constrained by conflicting hardware requirements for the reservoir (volatile, nonlinear) and readout (nonvolatile, linear) layers. Here, we resolve this dilemma by monolithically integrating a multi-timescale photoelectric reservoir and a linear ferroelectric readout within a single vertical organic field-effect transistor (Fe-vOFET). This architecture functionally decouples photocarrier dynamics from ferroelectric polarization, allowing orthogonal optimization of reservoir dynamics and synaptic weights. In the optical mode, the Rubrene/F16CuPc heterojunction underpins reservoir dynamics, exploiting wavelength-dependent relaxation kinetics to construct multi-timescale grouped reservoirs that project inputs into high-dimensional spatiotemporal states. Conversely, in the electrical mode, the metal–ferroelectric–metal–insulator–semiconductor (MFMIS) stack governs readout functionality by mitigating interface trapping, translating remnant polarization into linear, symmetric, nonvolatile weight updates (endurance >106, retention >3000 s, asymmetry nonlinearity 0.31 ± 0.05). The vertical-channel geometry is pivotal, simultaneously amplifying optical feedback and boosting the on/off ratio to ~107, which is essential for high-fidelity weight mapping. Leveraging this dual-mode operation, we demonstrate a compact RC system achieving >90% accuracy in dynamic human-action recognition. This work establishes a scalable device paradigm that unifies dynamical richness with programming precision, paving the way for energy-efficient, all-in-one dynamic machine vision systems. A dual-mode Fe-vOFET integrates multi-timescale photoelectric reservoirs and linear nonvolatile ferroelectric readout, enabling compact, efficient dynamic machine vision with high recognition accuracy.
Abstract Moiré superlattices of twisted bilayer 2D materials creating nontrivial physical effects have recently revolutionized diverse subjects across materials, optoelectronics, nanophotonics, and beyond. Here, we present moiré superlattices in higher-dimensional freespace optics, where the basic twisted lattice is not a layer of 2D material, but a propagating structured light field with periodic topological textures. The moiré structured light with flexibly tuned twist angle can generate and transit among a rich set of topologies, including skyrmionium bags, skyrmion bag superlattices, skyrmion clusters, and quasicrystals, with controlled symmetry, most of which were not discovered in any other systems. Importantly, our freespace moiré textures maintain their topologies over long-distance propagation with nondiffractive behavior and topological robustness against perturbations and obstacles. Our work unlocks higher dimensions of moiré photonics to manipulate super-resilient topologies and address the challenges of robust information transfer and encryption.
Frequency combs are multimode photonic systems that underlie countless precision sensing and metrology applications. Since their invention over two decades ago, numerous efforts have pushed frequency combs to broader bandwidths and more stable operation. More recently, quantum squeezing and entanglement have been explored in single-comb systems for continuous-variable quantum computing and quantum-enhanced spectroscopy. However, the production of bright quantum light across multiple nondegenerate pulses or frequency combs, a key technology for multispectral applications, remains largely unexplored. In this work, we explore a mechanism that generates a series of nonlinearly coupled bright frequency combs through cascaded three-wave upconversion and downconversion processes mediated by a single idler comb. We consider both discrete combs and broadband ultrafast pulse systems, showing how these systems generate inter- and intracomb two-mode squeezing and entanglement directly in the frequency basis, spanning a large spectral range. Furthermore, we demonstrate how these systems can be engineered to produce target cluster states and concentrated two-mode squeezing through covariance matrix optimization. Our findings uncover a new multimode quantum regime enabled by hierarchical nonlinear interactions in two frequency dimensions, unlocking applications such as entanglement-assisted spectroscopy, squeezing-enhanced pump-probe measurements, quantum spectral multiplexing, and spectrally addressable cluster state generation for quantum information science. A cavity with idler-mediated cascaded second-order nonlinearity generates a nondegenerate system of nested frequency combs, enabling long-range quantum squeezing across distinct spectral bands and multipartite entanglement for cluster states.
