Significant research efforts have focused on developing novel optoelectronic devices utilizing two-dimensional (2D) transition-metal dichalcogenides (TMDs), motivated by their strong light-matter interactions and unique material properties. Photodetectors simultaneously achieving high-speed and high-responsivity performance are particularly crucial for applications such as high-data-rate interconnects operating at telecom wavelengths. However, the intrinsically limited carrier mobilities in TMDs present a fundamental bottleneck for a high-speed operation. Here, we demonstrate high-performance monolayer MoS2 photodetectors fabricated via chemical vapor deposition (CVD) and monolithically integrated with a dielectric waveguide. The Au-MoS2-Au device architecture minimizes carrier transit path lengths while exploiting the short lifetime of hot electrons, yielding a measured bandwidth of similar to 3.28 GHz. Concurrently, the device achieves a high responsivity of 144 mA W- 1 at 1529.3 nm, attributed to an integrated tapered-waveguide design that significantly enhances the light-matter interaction region. This in situ synergistic integration of wafer-scale CVD-grown TMDs with planar, etch-free photonic circuits establishes a versatile platform for realizing high-performance on-chip optoelectronic devices.

Achieving broadband second-order nonlinear processes in a fully integrated fiber platform has long been a challenge, as silica fibers intrinsically lack second-order nonlinear susceptibility due to their centrosymmetric and amorphous structure. Here, we introduce an all-fiber strategy that overcomes this limitation by integrating microfibers with few-layer gallium selenide crystals, enabling controlled and broadband optical frequency mixing. We reveal the critical role of time-domain synchronization in sum-frequency generation (SFG) and demonstrate multi-frequency mixing from four continuous-wave sources, producing ten converted wavelengths through simultaneous second-harmonic generation (SHG) and SFG. Remarkably, the system operates at low excitation thresholds, supporting broadband SFG with two superluminescent diode sources and yielding an unprecedented SHG continuum extending to ~180 nm with a supercontinuum source. Furthermore, the broadband SFG spectrum can be tuned over 70 nm by coupling with a quasi-monochromatic laser. This approach establishes a scalable and versatile platform for regulating the wavelength and bandwidth of nonlinear processes in optical fibers, opening pathways toward tunable broadband light sources and advanced all-fiber photonic technologies.

Optoelectronic memristive devices that enable neuromorphic sensory computing with integrated sensing, memory and processing functionalities, have been identified as a promising element for next-generation artificial vision systems. However, the optoelectronic memristive dynamics of these devices are largely based on engineered structures and/or innovative functional nanomaterials, presenting critical challenges for their silicon complementary metal-oxide-semiconductor (CMOS) technology compatibility at a scalable application perspective. Here we demonstrate a CMOS-compatible optoelectronic memristive device based on the aluminium scandium nitride (AlScN) ferroelectric/two-dimensional (2D) semiconductor heterostructure enabled ferroelectric field-effect transistor (FeFET). We show that such FeFETs can be fabricated under the back-end-of-line (BEOL) thermal budget and exhibit non-volatile electronic memory properties. Harnessing the light-induced ferroelectric domain reconfiguration in the AlScN layer, these devices offer light-tunable short- and long-term memristive properties, directly linking light stimulation history to electronic dynamics. Such a working principle enables rich optoelectronic synaptic functions and the implementation of the psychological human visual memory model, offering a critical demonstration for optical neuromorphic sensory computing. Furthermore, a linear and non-volatile dependence of the photoresponse current on the light intensity is exploited for the optical information decoding. Our results mark new opportunities for CMOS-compatible optoelectronic memristive devices as the hardware basis of next-generation neuromorphic vision architectures.

Two-dimensional (2D) van der Waals heterojunctions have attracted tremendous attention due to their excellent electronic and optoelectronic properties. However, conventional unipolar 2D heterostructures generally exhibit unidirectional rectification behavior and rarely possess bidirectional rectification characteristics, which limits the reusability of the devices. Herein, we designed a bidirectional rectification photodetector based on Ta2NiSe5/ReSe2 heterojunctions, leveraging the ambipolar nature of ReSe2 and the narrow bandgap of Ta2NiSe5. This unique material combination breaks through the unidirectional rectification bottleneck of conventional 2D heterojunction. This work reveals that photogenerated carrier tunneling can be simultaneously regulated at both the heterojunction interface and drain Schottky contact under gate voltage modulations, which is analyzed via transport current fitting and energy band analysis. Results show rectification ratios up to similar to 10(4) and similar to 10(5) under +/- 60 V gate voltages, respectively. Notably, it exhibits photodetection performance over 520-980 nm, with fast microsecond level photoresponse. This work demonstrates great application prospects of the Ta2NiSe5/ReSe2 heterojunction photodetector in advanced optoelectronics, providing a new strategy for high-performance, multifunctional photodetectors.

ABSTRACT While advancements in optical fiber‐based second harmonic generation (SHG) have leveraged novel waveguide designs and two‐dimensional nonlinear material integration, conventional fiber schemes remain constrained by limited multi‐frequency control and restricted efficiency growth. We demonstrate an all‐fiber resonant SHG strategy achieving periodic enhancement and polarization modulation by integrating a few‐layer GaSe crystal with a microfiber knot resonator (MKR). Benefitting from MKR‐enabled resonant interaction with GaSe, which possesses ultrahigh second‐order nonlinear susceptibility, the maximum excitation of comb‐like SHG at resonant wavelengths achieves a 32‐fold enhancement compared to GaSe‐microfiber integration under continuous‐wave laser pumping. Meanwhile, the twisted MKR structure facilitates dynamic polarization‐dependent control of the split SHG wavelengths through pump polarization modulation. Experimental results further reveal distinct intensity patterns of SHG intensity in both under‐coupling and over‐coupling regimes. Our findings offer insights into accessing broad, efficient, polarization‐controllable SHG combs for multifunctional nonlinear photonic devices with on‐demand spectral tailoring capabilities.

Advances in microwave photonics call for the investigation of Fano resonances in the microwave domain for efficient signal generation and processing. While emerging integrated acousto-optic (AO) technology provides a promising approach for this purpose, Fano resonances in these systems have seldom been reported. Here, based on a polymer-loaded lithium niobate on insulator (LNOI) platform, we achieve efficient AO and electro-optic (EO) coupling in a well-designed photonic crystal nanobeam cavity (PCNBC), enabling Fano resonance in the microwave domain within a single AO modulator. The characteristics of the Fano resonance are strongly determined by the acoustic modes. By adjusting the gap between the PCNBC and the interdigital transducer, the Fano resonance can be periodically tuned for a given acoustic mode. Additionally, its dependence on radio-frequency power is demonstrated, achieving a high extinction ratio up to 44 dB at a low radio-frequency power of -25 dBm. This work provides an approach to achieve the Fano resonance in the microwave domain, promoting the development of the AO-based devices in microwave photonics.

Chalcogenide polymeric materials have emerged as promising, cost-effective alternatives to conventional infrared materials. In this Letter, we demonstrate the fabrication of micro-optics elements using a flexible chalcogenide polymer with an extended transparency window into the long-wave infrared region. Employing this thermoset S-DADS polymer, broadband infrared micro-optical components were fabricated via casting processes. Experimental results validate their functionality in IR imaging, wavefront sensing, and mechanically tunable beam shaping, which shows their potential for diverse infrared applications.

Plasmon-exciton coupling effect plays a crucial role in light emission and quantum control, which, however, has not been reported in nonmetallic systems until now. Topological insulators (TIs), with breaking through the limitations of traditional metallic materials on the operating frequency range and photonic integration, offer a new platform for exploring surface plasmons and their interaction with matter. Herein, we experimentally demonstrate the scattering resonance response of surface plasmons in the antimony telluride (Sb2Te3) TI metasurfaces with focused ion beam (FIB)-fabricated nanowells as well as the coupling behaviors between the plasmons and excitons in atomic-layer tungsten disulfide (WS2) semiconductors. The measured results show that the wavelength of scattering resonance presents a redshift with increasing the depth and pitch of TI nanowells. In WS2/TI metasurface heterostructures, we observe the obvious coupling effect between the TI plasmons and excitons in WS2 atomic layers. The theoretical analysis reveals that the plasmon-exciton interaction is located in the weak coupling regime with the generation of Fano resonance, inducing strong photoluminescence (PL) enhancement of WS2 atomic layers. This work will open a new door for plasmon-exciton coupling and applications of TIs in compact optoelectronic devices.

The optical characterization of atomic-layer materials requires the quantitative determination of both their complex refractive indices (RIs) and thickness. However, existing methods rely on preset thicknesses, empirical models, or auxiliary characterization tools. It remains a challenge to jointly retrieve real part n, imaginary part k, and thickness d of ultrathin samples in a wide-field manner and over a broad measurement range. Here, we propose an angle-scanning surface plasmon resonance (SPR) holographic microscopy. This method utilizes the modulation effect of sample parameters (n, k, d) on SPR phase shifts and retrieves them by fitting measured phase shifts with theoretical counterparts at multiple angles. Measurements of monolayer, bilayer, and multilayer graphene samples validate the effectiveness of this method and demonstrate its broad measurement range from monolayer to tens of nanometers. A step-like sample further confirms its wide-field measurement capability. This work provides an optical approach for jointly characterizing the complex RIs and thickness of graphene, with potential applicability to other atomic-layer materials.

In monolayer semiconductors, excitons confined by strain-induced potential traps are promising candidates for on-chip single-photon sources. For these quantum emitters, achieving broadband tunability while preserving high brightness is crucial for quantum information processing and communication, but remains challenging in aligning the emitter energy with optical resonances. Here, we demonstrate resonant tuning of localized exciton emission in monolayer WSe2 using an Au nanocube-on-mirror nanocavity. The design enables simultaneous strain-induced exciton energy tuning and Purcell-enhanced emission. By adjusting the cavity gap, it allows precise spectral alignment of the localized exciton with the plasmonic resonance. We observe a record-large redshift over 240 meV in localized exciton energy. Compared with the conventional approach, a 22-fold enhancement in emission intensity is achieved due to the spectral, spatial, and polarization matching between the localized exciton and plasmons. Our findings establish a robust strategy for developing high-performance nonclassical light sources, facilitating the development of scalable quantum applications.

In an era characterized by exponential digital growth and escalating cybersecurity threats, traditional encryption methods grapple with issues such as quantum vulnerability and static electromagnetic limitations. This paper introduces a transformative reconfigurable metasurfacebased pixel-wise visual cryptography (VC) framework. By integrating field-programmable gate arrays (FPGAs), the system dynamically encodes secrets into noise-like visual keys (VKs), which unveil content solely through electromagnetic superposition. Treating each 2 x 2 pixel as an independent encryption unit, it enables fine-grained control and real-time key reconfiguration, emulating the "one-time pad" principle to resist brute-force, machine-learning, and replay attacks. The pixel-wise encoding overcomes the coarse resolution constraints of traditional visual secret sharing, facilitating high-fidelity encoding of complex content, including alphanumeric text and high-resolution images. Experimental results demonstrate its robust performance, exhibiting notable tolerance to phase noise and reliable decryption even in the presence of partial hologram damage. This framework ensures information-theoretic security by eliminating statistical correlations between encryption cycles, outperforming traditional visual secret sharing (VSS) in resisting partial key interception.

ABSTRACT The development of reconfigurable photonic devices demands dynamic, non‐invasive control of nonlinear optical processes at the nanoscale. While second‐harmonic generation (SHG) in 2D materials (e.g., MoS 2 ) is a promising candidate, its active modulation remains challenging. Here, we report an all‐optical strategy for on‐demand writing and erasing of SHG in few‐layer MoS 2 . By alternating ultraviolet‐ozone treatment and continuous 532 nm laser irradiation, we achieve fully reversible, cyclic modulation of the SHG intensity exceeding 80‐fold. Our comprehensive spectroscopic and microscopic characterizations indicate that the tunability arises from the metastable formation and removal of surface S─O bonds, which transiently break lattice inversion symmetry. Leveraging this reversible control, we demonstrate spatially selective patterning of SHG, enabling the writing, erasing, and rewriting of optical information on a single MoS 2 flake. This work establishes a simple, non‐destructive platform for reconfigurable nonlinear photonics, with direct implications for optical memory, logic, and encryption technologies.

Rapid and accurate access to complete wavefront information is essential for advancing in the field of light science. Recent advances in metasurfaces have led to the swift development of compact quantitative phase and polarization imaging techniques. However, the concurrent retrieval of intensity, phase, and polarization information via meta-optic systems remains limited. Here, a meta-optics-based sensing architecture capable of simultaneously capturing the amplitude, phase, and polarization of light fields is proposed. It utilizes a multichannel metasurface with polarization-encoded quadrifocal phase to generate space- and polarization-multiplexed intensity patterns, then reconstructs the complex amplitudes of two spin components from longitudinal differentiation of intensity images via the transport of intensity equation, thereby achieves single-shot quantitative sensing of full-wavefront parameters. This non-interferometric architecture is compatible with and scalable to conventional imaging systems. Experimental results demonstrate its application in the high-accuracy, real-time, multidimensional characterizations of micro-optical elements and osteoblasts. This work offers distinct advantages for the analysis of biological tissues and materials that require concurrent phase and polarization measurements.

Objective Slow light photonic crystal waveguides (PCWs) have shown great potential in integrated optics, particularly for applications requiring enhanced light-matter interaction, optical delay, and compact nonlinear components. However, the trade-off between achieving high group index (n(g)) and broad bandwidth remains a key challenge in chip-scale implementations. This work aims to address this issue by proposing a dispersion-engineered PCW design based on the W1 line-defect configuration. The approach combines first-row air-hole truncation and second-row cooperative modulation to realize wide flat-band slow-light transmission, while maintaining structural simplicity and fabrication compatibility. Furthermore, a square Fabry-Perot (FP) cavity is introduced at the waveguide terminal, and is employed in both numerical analysis and experiments to validate the slow-light properties via spectral analysis, enabling accurate extraction of n(g) variation. Methods The structure is designed on a 220-nm-thick silicon slab corresponding to the device layer of a standard silicon-on-insulator (SOI) platform, with a buried oxide underneath providing vertical index contrast in the fabricated devices. In plane, a triangular lattice with a period of 414 nm and an initial air-hole radius of 0.29a is patterned, and a W1 line defect is formed along the Gamma-K direction by removing one row of holes. Different from a conventional W1, the first-row air holes next to the defect are laterally cut to form Dshaped truncated holes, and the remaining part is defined as D '. Reducing D ' increases the local effective index and shifts the guided band, so that a low-dispersion slow-light segment can appear before the intrinsic band edge (Figs. 1(b) and 1(c)). On this basis, a second degree of freedom is introduced by tuning the position or the radius of the second-row holes (Fig. 2): in one case, the holes are shifted toward the line defect; in the other case, their radius is enlarged. Both operations target further dispersion suppression around the designed wavelength. To verify the design on real devices, a pair of square air holes is added at the end of the optimized PCW to form an on-chip FP cavity of 40 mu m in length, and the ng is retrieved from the spacing of adjacent resonances and compared with the numerical results (Fig. 3, Fig. 4). Results and Discussions Band-structure and n(g) calculations show that truncating the first-row holes shifts the guided band toward lower normalized frequency, and more importantly, turns the previously steep rise of the n(g) curve into a segment that becomes flat before the band edge is reached (Fig. 1(c)). When D ' is reduced to 0.6D or 0.5D, a practically usable slow-light window appears in the telecom band, in which the n(g) variation is limited while the average value stays high. Based on this truncated configuration, shifting the second-row holes toward the defect strengthens the mode-lattice interaction and pushes the band to higher frequency; with a shift of s=0.12a, the sharp n(g) peak is transformed into a flatter distribution with a low-dispersion bandwidth of 8.25 nm, a relatively high n(g) of 47.63, and a corresponding normalized delay bandwidth product (NDBP) of 0.249, which is suitable for on-chip delay and nonlinear interaction (Figs. 2(a) -(c)). In the alternative route, enlarging the second-row radius to r '=1.16r produces a red-shifted slow-light window; although the peak ngis slightly lower than that of the shifted case, the flat slow-light bandwidth is broadened to 16.6 nm and the n(g) is 29.3, resulting in an NDBP of similar to 0.307 (Fig. 2(d)-(f)). Thus, the two optimizations are complementary: position shift favors higher n(g), while radius enlargement favors wider usable bandwidth. To confirm that these effects are not limited to simulations, both optimized PCWs were terminated by square mirrors to form FP cavities, and their transmission spectra were numerically obtained (Fig. 3). For the structure with a second-row position shift (s=0.12a), the simulated resonance spacing decreases toward the target band, and the FSR-extracted n(g) is 45, which is in good agreement with the bandgap structure results, exhibiting a flat slow-light region with a bandwidth of 8.1 nm (Fig. 3(b)). For the structure with an enlarged second-row radius (r '=1.16r), the same FSR analysis yields a red-shifted and slightly broader flat slow-light window, consistent with the calculated dispersion (Fig. 3(c)). Based on this, fabricated SOI devices were measured. SEM images confirm that the truncated first row, the tuned second row and the square cavity can all be fabricated with good uniformity (Fig. 4(a), Fig. 4(d)). The n(g) retrieved from the measured FP spectra is 40, with a flat region of 6.1 nm, consistent with the simulation results in Fig. 3 (Fig. 4(b), Fig. 4(c), F ig. 4(e), Fig. 4(f)). Conclusions This work numerically designed and experimentally demonstrated a slow-light PCW featuring a truncated first row of air holes jointly tuned with a second-row air-hole modification. The proposed structure preserves the simplicity and CMOS compatibility of the W1-type PCW. With the first-row truncation fixed at D '=0.6D, numerical results show that the position-offset design achieves a high group index slow light regime at s=0.12a, delivering (n) over bar (g)=47.63 and Delta lambda =8.25 nm with a corresponding NDBP of 0.249. By contrast, increasing the second row hole radius to r ' = 1.16r reduces (n) over bar (g) to 29.26 but expands the low-dispersion bandwidth to 16.59 nm, boosting the NDBP to similar to 0.307. By integrating a square FP cavity and retrieving ng from the measured FSR, both optimized structures yield a flat slow-light window with (n) over bar (g)=40, where Delta lambda is 6.1 nm for s=0.12a and 9 nm for r '=1.16r; the slow-light window position and its evolution trend are consistent with the theoretical predictions. The proposed approach provides a feasible structural route for integrating slow-light-enhanced nonlinear optics, optical delay, and ultrafast pulse characterization in photonic integrated circuits.

Photodetectors (PDs) are vital in optical communications, environmental monitoring, and military applications. At present, conventional PDs face challenges such as high dark current, which restricts their further development in high-performance photodetection. Two-dimensional (2D) materials offer advantages for next-generation photodetection due to their atomic thickness, defect-free surfaces, and gate-tunable bandgaps, which enable efficient channel modulation and ultralow dark current. This work presents a high-performance phototransistor that integrates topological semimetal NbSe2 source/drain electrodes and an underlying graphene (Gr) auxiliary layer to construct a ReS2/Gr heterojunction. The NbSe2 contacts mitigate Fermi-level pinning, while the underlying Gr auxiliary layer, not directly contacted by electrodes, significantly enhances device performance. At 14.9 mW/cm(2) of light intensity and -20 V of gate voltage, the ReS2/Gr device shows a higher responsivity of 1261.59 mA/W, which is 1726% higher than that of the ReS2 device. Besides, the specific detectivity and external quantum efficiency (D* = 7.20 & times; 10(11) Jones and EQE = 2.29 & times; 10(4)%) are much larger than those of the ReS2 device (D* = 4.17 & times; 10(10) Jones and EQE = 171%). The ReS2/Gr device also exhibits faster response speeds (t(rise) = 32.5 mu s, t(fall) = 45.7 mu s) compared to the ReS2 device (t(rise) = 3.23 ms, t(fall) = 4.27 ms), demonstrating a two-order-of-magnitude improvement in temporal response. Moreover, it shows excellent performance in optical communications and single-pixel imaging, successfully decoding an ASCII signal and capturing a high-contrast pattern. These results validate its potential for practical applications in optical communication and imaging, offering a representative demonstration for the optimization of 2D material PDs.

We demonstrate an on-chip electro-optic modulator with colloidal In 2 O 3 nanocrystals, which are integrated on a silicon photonic chip with a simple spin-coating process. The modulator has an electrical capacitor-like structure with In 2 O 3 and silicon as the two semiconductor electrodes, which are separated by an Al 2 O 3 dielectric layer. With the electrical voltage applied to the two semiconductor layers, their carrier densities are changed considerably, and subsequently, the complex refractive indices. As a result, from an In 2 O 3 -coated silicon microring resonator, the resonance lineshape and central wavelength are modified. The resonance wavelength tunability is 15.7 pm/V, resulting in a modulation depth exceeding 13 dB. A modulation efficiency V π · L of 0.56 V·cm, a static power consumption of 2.5 pW/nm, and a per-bit power consumption of 2.34 pJ/bit under a driving voltage of 2 V pp are realized. Our work provides a viable route for CMOS-compatible, high-throughput, and cost-effective solution-based electro-optic modulators for photonic integrated circuits.

Supercontinuum generation (SCG) on integrated photonic platforms is a pivotal technology for developing next-generation chip-scale systems for precision spectroscopy and metrology. While significant progress has been made with silicon (Si) and silicon nitride (Si_3N_4) platforms, they are often constrained by two-photon absorption (TPA) or moderate nonlinear coefficients, necessitating a trade-off between energy efficiency and bandwidth. Tantalum pentoxide (Ta_2O_5), possessing both high nonlinearity and a wide bandgap, emerges as a promising candidate; however, current implementations remain challenged by high pump energy consumption. Here, we report a low-loss Ta_2O_5 integrated waveguide fabricated via the Damascene process. It enables the generation of a two-octave-spanning spectrum with a low pulse energy of only 92.9 pJ (60 fs, 1550 nm). Notably, the corresponding peak power is a mere 1.36 kW, which is nearly an order of magnitude lower than that of state-of-the-art comparable broadband sources. Furthermore, at the maximum pump energy, our spectrum exhibits an ultrabroad coverage from 450 nm to 3400 nm, spanning nearly three octaves. Supported by numerical simulations, we analyze the dynamics of soliton fission. Furthermore, a Michelson interferometry system developed using this source exhibits superior performance, achieving not only micrometer-scale axial resolution but also a 6 dB sensitivity roll-off length of 3.1 mm. This exceptional roll-off performance, combined with a displacement measurement sensitivity of 346 nm, underscores the immense potential of the Ta_2O_5 platform for applications in biomedical imaging and precision metrology.