Erbium-doped/erbium-ytterbium co-doped waveguide amplifiers (EDWAs/EYCDWAs) have received much attention as essential components within large-scale functionalized silicon-based optoelectronic (SBO) chips for their remarkable ability to amplify optical signals on-chip at the communication band combined with their potential application across diverse fields. We reviewed the research progress of EDWAs/EYCDWAs comprehensively. In particular, the research advancements concerning amplifiers constructed with diverse host materials are introduced in detail, and the gain limitations of the waveguide amplifiers are thoroughly analyzed from multiple perspectives, such as host materials and innovative structural designs. Subsequently, the preparation processes of the gain medium and waveguide structure in EDWAs/EYCDWAs are discussed, and their common application scenarios and commercial applications are summarized. In addition, an assessment is carried out on the challenges encountered by EDWAs/EYCDWAs. Finally, a discussion is held on their potential applications and development prospects in the field of SBO chips, with the aspiration of providing valuable references for the development of EDWAs/EYCDWAs.

Quantum sensing aims to detect signals with unparalleled sensitivity, potentially surpassing classical limitations. Solid-state spin defects, particularly nitrogen-vacancy centers in diamond, have emerged as promising platforms due to their long coherence time, optical addressability, high field sensitivity, and spatial and spectral resolution, making them ideal for sensing and imaging applications. Their compact size and robust performance under room temperature and ambient conditions further enhance their suitability for real-world applications. We provide an overview of quantum sensing principles and explore efforts to improve sensor functionality, including advanced sensing protocols, spatial imaging techniques, and integration with optical systems to enhance detection efficiency. We also highlight recent progress in the applications of these sensors across various use cases, including biomedical diagnostics, semiconductor device inspection, and industrial and military applications.

We explore an emerging frontier in optical communications—leveraging optical computing and optical signal processing to restore degraded signals in space or mode-division multiplexing (SDM/MDM) systems. As SDM/MDM pushes toward ever-higher channel densities within a single fiber, inter-channel optical coupling leads to significant crosstalk. Due to group velocity mismatches, this crosstalk spatiotemporally entangles optical signal streams, significantly complicating multi-input multi-output digital signal processing (MIMO DSP) for signal recovery across both spatial and temporal domains. Free-space optical systems face similar challenges from multipath interference. We systematically appraise two strategic pathways of optically addressing the spatiotemporal interference: (1) optoelectronic computing that either accelerates conventional linear MIMO DSP or maps the problem onto physics-inspired models solvable by analog or hybrid optoelectronic systems and (2) all-optical processing that seeks to untangle the coupled optical signals directly within the optical domain. For both pathways, we evaluate architectural effectiveness and scalability based on rigorous mathematical analysis, aiming to offer insights into promising approaches for future research.

Pseudomagnetic fields (PMFs) can manipulate photons in a similar way that magnetic fields control electrons. However, the PMF-based control over light has been restricted to simple waveguiding of the Landau level states, which hinders the application of PMFs in practical photonic integrated circuits. Here, we propose a universal and systematic methodology to design complex nonuniform PMFs and arbitrarily control the flow of light in silicon photonic crystals at telecommunication wavelengths. As proofs of concept, an S-bend (with a low insertion loss of <1.83 dB) and a 50:50 power splitter (with a low excess loss of <2.11 dB and imbalance of less than ±0.5dB) based on PMFs are experimentally demonstrated. A high-speed data transmission experiment is performed on these devices with 140-Gb/s four-level pulse amplitude modulation signals to prove their applicability in real communication systems. The proposed method offers a paradigm for exploring magnetic-field-related physics with neutral particles and developing nanophotonic devices with PMF-induced states beyond the Landau level states and the topological edge states.

In two-dimensional (2D) organic–inorganic (O-I) heterostructures, interlayer coupling has emerged as a design parameter for engineering their electronic and optoelectronic properties, essential for designing future excitonic and optoelectronic devices. However, the further exploration of interlayer couplings is limited by their weak strength and ineffective tuning strategies, due to the inconsistent material quality and the bulky size of organic counterparts. Here, we integrate 2D pentacene single crystals with monolayer MoS2 to achieve strong interlayer coupling and effective tuning through a twisting method. We confirm this strong coupling through calculated lower interlayer spacing (∼2.70Å), high charge transfer efficiency (∼61%), and a high coupling strength of ∼2.72 at a twist angle of ∼32deg. Both density functional theory calculations and experimental results demonstrate the remarkable electrical control over interlayer couplings by adjusting electrical band alignments. This control over interlayer couplings helps to untangle the diffusion of neutral excitons and trions, which have diffusion lengths of ∼1.95 and 0.93μm, respectively. Our results underscore the significant tunability of interlayer couplings and relaxations within O-I systems via twist angles, offering avenues for developing high-performance vertical transistors, logic devices, photodetectors, and photovoltaic devices.

High-quality and real-time holographic imaging based on dynamically tunable metasurfaces has attracted immense interest. Despite remarkable progress, the complex electrical pattern designs and slow-speed near-field scanning terahertz (THz) microscopy systems have significantly hindered the development of real-time electrically tunable metasurface holography in the THz band. We propose and experimentally demonstrate an electrically tunable vanadium dioxide (VO2)-based active metasurface that can generate real-time bias-controlled holographic information via a THz focal plane imaging system. By elaborately designing "microladders" integrated with VO2 pads, the device exhibits low power consumption (∼0.8W) and real-time imaging (∼4.5s). The quantitative method is theoretically utilized to investigate the thermal parameters dependent thermodynamics of the "ladder" metasurface based on theoretical analysis with the aid of thermal modelling. The calculated dynamic response time based on the quantitative thermodynamic model agrees well with experimental results. Our study can be used to propel the development of THz electrically tunable metasurfaces for low-power-consumption dynamic, real-time displays, and information encryption, providing crucial insights for future optimization of VO2-based electrothermally tunable holographic metasurfaces.

Quantum entanglement networks have garnered significant attention due to the inherent security provided by quantum physics. The networks aim to connect a multitude of users with a high secure key rate (SKR). Fully connected networks have been demonstrated using wavelength-division multiplexing architectures. However, the SKR of such networks remains challenging due to the limited brightness of quantum photon-pair sources and the loss introduced by cascaded filtering components. We present high-rate quantum entanglement networks that leverage a broadband quantum light source with high brightness and an industry-grade flexible wavelength-selective switching technique with uniform loss. By implementing the BBM92 protocol, we achieve an SKR of 28.19 kbps in a four-user network, representing a two-order-of-magnitude improvement over previous implementations. After transmission through a 40-km fiber spool, the SKR remains as high as 3.58 kbps and stays positive over distances up to 250 km. Furthermore, the flexibility of our scheme is illustrated by constructing a six-user network, achieving SKRs of 4.21 kbps and 0.45 kbps without and with a 40-km fiber spool, respectively. These results demonstrate a practical approach to enhancing the SKR and scalability in entanglement-based quantum networks, offering a feasible solution for deploying metropolitan and backbone quantum communication systems.

The power monitor, a crucial component for programmable photonics, faces challenges in on-chip applications due to rigorous demands for low optical absorption loss, adequate responsivity, minimal dark current, and low power consumption. Currently, there are limited effective solutions that can simultaneously address all these issues within the existing photodetection technology for telecommunications bands on the silicon-on-insulator platform. Here, we present a first Ge+-implanted silicon waveguide photodiode (PD) monitor operating in the dual-band spanning telecommunications O- and C-bands. Ge, a complementary metal-oxide-semiconductor-compatible group IV element, can substitute a silicon atom at a lattice site with minimal introduction of extra free carriers. We demonstrate responsivities of 124.8mA·W−1·mm−1 at 1310-nm wavelength (O-band) and of 31.2mA·W−1·mm−1 at 1550-nm wavelength (C-band), with a low dark current of 0.8 nA upon a small bias voltage of −3V. The internal quantum efficiency exceeds that of B+-, P−-, and Ar+-implanted silicon PDs by factors of 4.9 to 16.8. The device exhibits optical absorption loss of <0.012dB·μm−1 and 98% linearity across <1mW on-chip power. Our Ge+-implanted silicon waveguide PDs hold significant promise in on-chip power monitors for programmable photonics.

Artificial intelligence-driven (AI-driven) data centers, which require high-performance, scalable, energy-efficient, and secure infrastructure, have led to unprecedented data traffic demands. These demands involve low-latency, high-bandwidth connections, low power consumption, and data confidentiality. However, conventional optical interconnect solutions, such as intensity-modulated direct detection and traditional coherent systems, cannot address these requirements simultaneously. In particular, conventional encryption protocols that rely on complex algorithms are increasingly vulnerable to the rapid advancement of quantum computing. We propose and demonstrate a quantum-secured data transmission architecture that involves minimal digital signal processing (DSP) consumption and meets all the stringent requirements for AI-driven data center optical interconnect (AI-DCI) scenarios. By integrating a self-homodyne coherent (SHC) system and quantum key distribution (QKD) through the multicore-fiber-based space division multiplexing (SDM) technology, our scheme enables secure, high-capacity, and energy-efficient data transmission while ensuring resilience against quantum computing threats. In our demonstration, we achieved an expandable transmission capacity of 2 Tbit per second (Tb/s) with a quantum secret key rate (SKR) of 229.2kb/s and further validated real-time encrypted transmission using AES-256 encryption with QKD-generated keys. Our work paves the way for constructing secure, scalable, and cost-efficient data transmission frameworks, enabling the next generation of intelligent, leak-proof optical interconnects for data centers.

The calibration process has always been an inevitable key step of light-induced thermoelastic spectroscopy (LITES) technology, which is also the current primary bottleneck hindering the widespread application. The complexity, high cost, and environmental sensitivity of such a process severely limit the sensing system’s ability to perform long-term, stable, and accurate measurements of the target. We propose a breakthrough calibration-free LITES sensing technique. The core innovation lies in the first-time utilization of quartz thermoelastic effect as the sensing mechanism, combined with full-range light intensity modulation to acquire the complete target gas absorption spectrum, from which absolute gas concentration and temperature values are directly extracted, eliminating the need for calibration. The concentration and temperature in this work were measured separately, among which, the temperature was retrieved by targeting two gas absorption lines. Theoretical research with experimental studies on gas concentration and temperature sensing was conducted. In terms of gas sensing, this technology can achieve the inversion of the different absolute gas concentrations without a calibration process using a quartz tuning fork (QTF). In terms of temperature measurement, this technology successfully achieves simultaneous inversion of two gas absorption lines with a single QTF and obtains the temperature field information. The experimental results also verified that this technology can accurately detect the target even when the laser power, QTF characteristics, and the optical path of the system change, providing an effective technical proposal for the long-term, stable, and accurate measurement of the analyte. Furthermore, it also offers the advantages of small size and wavelength independence, which make it well suited for miniaturization and extending sensing to mid-infrared or far-infrared wavebands.