Photonic Technologies Research Articles

Application Strategies of MXenes in Photodetector: Dual Perspectives of Acting as Modifiers and Being Modified

Photodetectors, as essential devices for photoelectric conversion, are critical to advancing military, industrial, and civil technologies. In the post‐Moore era, the demand for extreme miniaturization and multifunctionality has driven intense research into low‐dimensional materials. Two‐dimensional MXenes have attracted considerable attention due to their exceptional conductivity, controllable surface functional groups, and tunable bandgap associated with surface terminals. However, the lack of systematic analysis on how MXenes enhance photodetector performance, modification mechanisms, and the multifunctional applications of modified MXenes constrains progress in this field. Herein, this review focuses on the dual roles of MXenes as performance modifiers and modifiable materials in photodetectors. It systematically examines the preparation and modification strategies of MXenes. Emphasis is placed on their potential as conductive electrodes, carrier transport layers, and heterojunctions with photosensitive layers to optimize device performance. The impact of advanced modification techniques on MXene properties is also explored, along with their subsequent application in photodetectors with enhanced sensitivity and stability. Additionally, emerging opportunities for MXenes in enabling novel device architectures and multifunctional photodetection platforms are highlighted. Herein, strategic guidance is provided for photodetector structural design and material innovation and establishes a foundation for next‐generation optoelectronic devices and broader MXene integration in photonic technologies.

Pulse characterization at the single-photon level through chronocyclic Q-function measurements

The characterization of the complex spectral amplitude, that is, the spectrum and spectral phase, of single-photon-level light fields is a crucial capability for modern photonic quantum technologies. Since established pulse characterization techniques are not applicable at low intensities, alternative approaches are required. Here, we demonstrate the retrieval of the complex spectral amplitude of single-photon-level light pulses through measuring their chronocyclic Q −function. Our approach draws inspiration from quantum state tomography by exploiting the analogy between quadrature phase space and time-frequency phase space. In the experiment, we perform time-frequency projections with a quantum pulse gate (QPG), which directly yield the chronocyclic Q −function. We evaluate the complex spectral amplitude from the measured chronocyclic Q −function data with maximum likelihood estimation (MLE), which is the established technique for quantum state tomography. The MLE yields not only an unambigious estimate of the complex spectral amplitude of the state under test that does not require any a priori information, but also allows for, in principle, estimating the spectral-temporal coherence properties of the state. Our method accurately recovers features such as jumps in the spectral phase and is resistant against regions with zero spectral intensity, which makes it immediately beneficial for classical pulse characterization problems.

Advances in Photonic Materials and Integrated Devices for Smart and Digital Healthcare: Bridging the Gap Between Materials and Systems.

Recent advances in developing photonic technologies using various materials offer enhanced biosensing, therapeutic intervention, and non-invasive imaging in healthcare. Here, this article summarizes significant technological advancements in materials, photonic devices, and bio-interfaced systems, which demonstrate successful applications for impacting human healthcare via improved therapies, advanced diagnostics, and on-skin health monitoring. The details of required materials, necessary properties, and device configurations are described for next-generation healthcare systems, followed by an explanation of the working principles of light-based therapeutics and diagnostics. Next, this paper shares the recent examples of integrated photonic systems focusing on translation and immediate applications for clinical studies. In addition, the limitations of existing materials and devices and future directions for smart photonic systems are discussed. Collectively, this review article summarizes the recent focus and trends of technological advancements in developing new nanomaterials, light delivery methods, system designs, mechanical structures, material functionalization, and integrated photonic systems to advance human healthcare and digital healthcare.

A Gigahertz configurable silicon photonic integrated circuit nonlinear interferometer

Abstract Low loss and high-speed processing of photons is important to photonic quantum information technologies. The speed with which quantum light generation can be modulated impacts the clock rate of photonic quantum computers, the data rate of quantum communication and applications of quantum enhanced radio-frequency sensors. Here we use lossy carrier depletion modulators in a silicon waveguide nonlinear interferometer to modulate photon pair generation probability at 1 gigahertz (GHz) without exposing the generated photons to the phase dependent parasitic loss of the mod- ulators. The super sensitivity of nonlinear interferometers reduces power consumption compared to modulating the driving laser. This can be used for high-speed programmable nonlinearity in waveguide networks for quantum technologies and for optical quantum sensors.

Programmable quantum circuits in a large-scale photonic waveguide array

Over the past decade, integrated quantum photonic technologies have shown great potential as a platform for studying quantum phenomena and realizing large-scale quantum information processing. Recently, there have been proposals for utilizing waveguide lattices to implement quantum gates, providing a more compact and robust solution compared to discrete implementation with directional couplers and phase shifters. We report on the first demonstration of precise control of single photon states on an 11-dimensional continuously-coupled programmable waveguide array. Through electro-optical control, the array is subdivided into decoupled subcircuits and the degree of on-chip quantum interference can be tuned with a maximum visibility of 0.962 ± 0.013. Furthermore, we show simultaneous control of two subcircuits on a single device. Our results demonstrate the potential of using this technology as a building block for quantum information processing applications.

Effect of Core Geometry on Frequency Correlations and Channel Capacity of a Multimode Optical Fiber

Photons are the fundamental carriers of classical and quantum information across long distances via optical fibers. Multimode fibers with many transverse optical modes can support high‐capacity communication through space‐division multiplexing. While spatial correlations in light transmission via fibers have been investigated for counteracting mode mixing, less is known about frequency correlations, which are critical for high‐capacity communication using ultrashort pulses. This study uses complex wavefront shaping methods to investigate how core geometry affects the frequency correlation bandwidth of structured wavefronts in circular and rectilinear‐core fibers. Measurements reveal that rectilinear‐core fibers exhibit up to a 40% increase in frequency correlation bandwidth compared to circular core fibers, particularly when focusing light away from the fiber center—common in spatially multiplexed optical communication. This enhanced bandwidth results in a 20% boost in optical communication channel capacity, highlighting the potential of rectilinear core fibers. Furthermore, this observation of novel spatiotemporal wave correlations could be exploited for application of rectilinear core fibers in chip‐to‐chip interconnects for photonic quantum processors, contributing to scale up of photonic quantum technologies.

Exploring Second-Order Nonlinear Optical Properties of 10-(3, 5-dinitrophenyl)-9-(4-nitrophenyl)-8, 9-dihydro-1H-pyreno [4, 5-d] imidazole Chromophore: Insights from a DFT Study

Finding effective nonlinear optical (NLO) materials for potential use in electro-optic applications is crucial. Among the limitations in high-speed data transmission, efficient signal transmission is a key problem. Organic materials furnish tunable nonlinear properties, ease of fabrication, and the ability to exhibit high second-order nonlinearities, making it crucial to address improvements in efficiency, speed, and reliability by introducing new organic materials to the evolving demand for cutting-edge technologies in photonics. Here we report a new novel D-π-A type chromophore 10-(3, 5-dinitrophenyl)-9-(4-nitrophenyl)-8, 9-dihydro-1H-pyreno [4, 5-d] imidazole chromophore and investigation of its second order nonlinear optical properties using density functional theory. The main target is to analyse nonlinear optical properties of the molecule and estimate NLO properties by ωB97XD/6311++G (d, p) method. Hyperpolarizability (β) is reported as 368.02 × 10−31 esu which is 98 times higher than standard urea β value (3.728 × 10–31 e.s.u) also dipole moment (μ), linear polarizability (α). UV Visible spectra shows optical behaviour of the materials, while HOMO-LUMO and MEP gives insight into intermolecular charge transfer. In addition, natural bond orbital analysis was carried out to confirm the interactions and charge transfer within the molecule. These findings emphasize utilization of the organic molecule for potential applications in photonics.

Seq2Seq model with attention for predicting nonlinear propagation of ultrafast pulses in optical fibers

The propagation of ultrashort pulses in optical fibers exhibits highly complex nonlinear dynamics, which plays a central role in the development of light sources and photonic technologies. The mainstream of the existing methods for modeling and predicting complex nonlinear propagation dynamics of ultrashort pulses in optical fibers is based on recurrent neural networks (RNNs), which use a Multi-In-Single-Out (MISO) architecture to predict the optical pulse evolution recursively. This autoregressive model is severely limited by the error accumulation problem and also requires significant computational resources. Affected by the error accumulation problem, this method often leads to severe performance degradation in long sequence prediction tasks, thus limiting the practical application of the prediction model. In this work, we propose a new non-autoregressive model using a Single-In-Multi-Out (SIMO) architecture to simulate the highly nonlinear dynamics of ultrashort pulse propagation in optical fibers. Our model is validated on the public dataset. The results show that our model can significantly reduce the prediction error in modeling and predicting the complex nonlinear propagation of ultrashort pulses in optical fibers. In addition, the required computational resources and time spent are significantly reduced. As a whole, our proposed method comprehensively outperforms the mainstream methods in terms of efficiency, accuracy and practicality. We believe our work could bring new insights into the modeling and analysis of complex ultrafast nonlinear dynamics.

Deep-Ultraviolet AlN Metalens with Imaging and Ultrafast Laser Microfabrication Applications.

Deep-ultraviolet (DUV) light is essential for applications including fabrication, molecular research, and biomedical imaging. Compact metalenses have the potential to drive further innovation in these fields, provided they utilize a material platform that is cost-effective, durable, and scalable. In this work, we present aluminum nitride (AlN) metalenses as an efficient solution for DUV applications. These metalenses, with a thickness of only 380 nm, deliver DUV focusing and imaging capabilities close to the theoretical diffraction limit. Leveraging their robustness to intense ultrafast laser irradiation, we demonstrate successful DUV ultrafast laser direct writing of microstructures on a polymer film and silicon substrate. These results underscore the significant promise of advancing photonic technologies in this critical wavelength regime.

Ultrafast expansion kinetics of femtosecond laser-induced optical breakdown in bulk fused silica

Abstract In this study, we employ femtosecond pump-probe shadowgraphy and complex Nomarski interferometry to investigate the ultrafast dynamics of laser induced plasma and shock waves (SWs) in bulk fused silica subjected to high laser intensities. It was found that the development of the plasma channel takes on a columnar shape with minimal variations during the early expansion stage between 130-200 ps. However, after 200 ps, the cylindrical SW started disintegrating from the plasma channel and gradually expanded outward
along the radial direction. The spatial distribution of transient electron densities along the plasma axis reached approx. 1.9 ∗ 1020cm−3, at a delay time of 50 ps. The resulting change in refractive index caused by electronic plasma is 0.05, while the reflectivity of the probe beam is ≈ 0.03 ‰. The blast wave model described the plasma and cylindrical SW expansion. A peak pressure and temperature of 65 GPa and 15 eV were registered at a delay time of 150 ps, respectively. The resulting extreme conditions mapped to the cross-section analysis of the void and SW-affected area inside the fused silica reveal polycrystalline structures near the periphery of the cavity at geometrical focus. However, all other points distinctively show the presence of an amorphous phase. These findings enrich the interpretation of femtosecond laser-dielectric interactions, with significant implications for micromachining, optical data storage, and the advancement of photonic device technologies.

Simultaneous measurement of multimode squeezing through multimode phase-sensitive amplification

Multimode squeezed light is an increasingly popular tool in photonic quantum technologies, including sensing, imaging, and computation. Meanwhile, the existing methods of its characterization are technically complicated, which reduces the level of squeezing, and mostly deal with a single mode at a time. Here, for the first time, to the best of our knowledge, we employ optical parametric amplification to characterize multiple squeezing eigenmodes simultaneously. We retrieve the shapes and squeezing degrees of all modes at once through direct detection followed by modal decomposition. This method is tolerant to inefficient detection and does not require a local oscillator. For a spectrally and spatially multimode squeezed vacuum, we characterize eight strongest spatial modes, obtaining squeezing and anti-squeezing values of up to −5.2 ± 0.2 dB and 8.6 ± 0.3 dB, respectively, despite the 50% detection loss. This work, being the first exploration of an optical parametric amplifier’s multimode capability for squeezing detection, paves the way for the real-time detection of multimode squeezing.

Reconfigurable Free Form Silicon Photonics by Phase Change Waveguides

AbstractThe rapid reprogramming of photonic integrated circuits (PICs) offers transformative potential for photonic technologies. Traditional programmable photonic devices, relying on thermo‐optic or electro‐optic effects, face limitations like large size and high energy consumption. Chalcogenide phase‐change materials (CPCMs) have gained attention for enabling energy‐efficient, non‐volatile optical manipulation on‐chip, crucial for in‐memory optical computing. Sb₂S₃ emerges as a promising alternative to conventional CPCMs, providing low loss and reversibility. This work introduces a CMOS‐compatible reconfigurable waveguide platform using Sb₂S₃ thin film on silicon‐on‐insulator (SOI). Laser direct writing enables the creation of complete channel waveguides in a single step, with the flexibility to erase and rewrite segments for rapid design adjustments. The platform demonstrates stable waveguide erasure using a cost‐effective laser engraver and low‐loss coupling between SOI and the phase‐change material‐on‐silicon (PCMoS) waveguide. By combining an economical fabrication process with a robust device architecture, this integration scheme offers a versatile solution for applications such as optical interconnects, neuromorphic and quantum computing, and microwave photonics.

Reversible Ferroelectric Polarization Modulation of Chiral Molecular Ferroelectrics by Circularly Polarized Light.

The optical modulation of ferroelectric polarization constitutes a transformative, non-contact strategy for the precise manipulation of ferroelectric properties, heralding advancements in optically stimulated ferroelectric devices. Despite its potential, progress in this domain is constrained by material limitations and the intricate nature of the underlying mechanisms. Recent studies have achieved efficient regulation of ferroelectric polarization and thermal conductivity in chiral ferroelectric thin films through the application of left- and right-handed circularly polarized light (LCP and RCP). Differential absorption of circularly polarized light (CPL) induces nonequilibrium carrier dynamics, generating distinctive interfacial electrostatic fields that enable precise control of ultrathin ferroelectric films. For (R)-BINOL-DIPASi and (S)-BINOL-DIPASi (C26H26O2Si), polarization changes surpass 23%, exhibiting opposite response under LCP and RCP excitation. In R chiral films, remnant polarization decreases from 1.05 µCcm- 2 under LCP to 0.85 µCcm- 2 under RCP, whereas in S chiral films, polarization increases from 0.85 µCcm- 2 under LCP to 0.98 µCcm- 2 under RCP. This reversible modulation facilitates reliable switching between ON and OFF states, presenting the potential of chiral ferroelectric materials for flexible, high-speed integrated photonic sensor technologies.

Investigating spin-orbit interaction of light in micro- and nanophotonic systems using polarization Mueller matrix

Coupling between the spin and orbital angular momentum of light has led to a variety of exotic spin–orbit photonic effects, establishing a paradigm of nanophotonic meta-devices to control and manipulate light at the nanometer length scale. For the advancement of spin–orbit photonic technologies, quantitative characterization and unambiguous physical interpretation of the various spin–orbit interaction (SOI) effects exhibited in complex nanophotonic systems are of utmost importance. This Perspective addresses some of these outstanding challenges in the domain of spin–orbit photonics, focusing on the simultaneous manifestation of multiple SOI effects in hybridized nanophotonic systems and the role of polarization-based techniques in their characterization and quantification. After introducing the fundamentals and physical origins of SOI effects, we present a polarization Mueller matrix technique as a powerful tool to probe, decouple, and independently quantify these effects in a unified experimental framework, demonstrated with hybridized waveguided plasmonic crystals. We further discuss the potential of structured light and tailored polarization to enable unconventional SOI phenomena in simple nanostructured metamaterials and metasurfaces. These advancements not only enhance our fundamental understanding of SOI phenomena across micro- and nanoscale optical systems but also pave the way for the development of multifunctional and tunable spin–orbit photonic devices.

Tailoring second harmonic generation in a multilayer WS2 flake via a silicon circular Bragg grating.

Nonlinear emission phenomena observed in transition metal dichalcogenides (TMDCs) have significantly advanced the development of robust nonlinear optical sources within two-dimensional materials. However, the intrinsic emission characteristics of TMDCs are inherently dependent on the specific material, which constrains their tunability for practical applications. In this study, we propose a strategy for the selective enhancement and modification of second-harmonic generation (SHG) emission in a multilayer WS2 flake through the implementation of a silicon (Si)-based circular Bragg grating (CBG) structure positioned on an Au/SiO2 substrate. By selectively exciting the region of the circular Bragg grating with the grating oriented either parallel or perpendicular to the linearly polarized pump beam, we successfully achieved wavelength-tunable SHG intensity peaks at 402.5 nm and 425 nm for the respective alignments. Our experimental findings, corroborated by numerical simulations, indicate that the enhancement of SHG intensity is highly sensitive to the orientation of the grating region of the CBG. Power-dependent SHG spectra further validate the quadratic dependence of SHG, while comparative analysis with WS2 flakes on a bare Si/Au/SiO2 substrate highlights the critical role of the CBG structure in modulating SHG. This research underscores the potential of CBG-augmented TMDCs for the control of nonlinear optical emissions, suggesting promising applications in photonic devices and selective emission technologies.

Room Temperature Quantum Emitters in van der Waals α-MoO3.

Quantum emitters in solid-state materials are highly promising building blocks for quantum information processing and communication science. Recently, single-photon emission from van der Waals materials has been reported in transition metal dichalcogenides and hexagonal boron nitride, exhibiting the potential to realize photonic quantum technologies in two-dimensional materials. Here, we report the generation of room temperature single-photon emission from exfoliated and thermally annealed single crystals of van der Waals α-MoO3. The second-order correlation function measurement displays clear photon antibunching, while the luminescence intensity exceeds 0.4 Mcts/s and remains stable under laser excitation. The theoretical calculation suggests that an oxygen vacancy defect is a possible candidate for the observed emitters. Together with photostability and brightness, quantum emitters in α-MoO3 provide a new avenue to realize photon-based quantum information science in van der Waals materials.

Integration of Functional Materials in Photonic and Optoelectronic Technologies for Advanced Medical Diagnostics.

Integrating functional materials with photonic and optoelectronic technologies has revolutionized medical diagnostics, enhancing imaging and sensing capabilities. This review provides a comprehensive overview of recent innovations in functional materials, such as quantum dots, perovskites, plasmonic nanomaterials, and organic semiconductors, which have been instrumental in the development of diagnostic devices characterized by high sensitivity, specificity, and resolution. Their unique optical properties enable real-time monitoring of biological processes, advancing early disease detection and personalized treatment. However, challenges such as material stability, reproducibility, scalability, and environmental sustainability remain critical barriers to their clinical translation. Breakthroughs such as green synthesis, continuous flow production, and advanced surface engineering are addressing these limitations, paving the way for next-generation diagnostic tools. This article highlights the transformative potential of interdisciplinary research in overcoming these challenges and emphasizes the importance of sustainable and scalable strategies for harnessing functional materials in medical diagnostics. The ultimate goal is to inspire further innovation in the field, enabling the creation of practical, cost-effective, and environmentally friendly diagnostic solutions.

Breaking Performance Barriers in KBe2BO3F2 (KBBF) Analogs by Functional Group Self‐Polymerization

AbstractEnhancing the conversion efficiency of all‐solid‐state lasers through the rational design of crystal materials with superior linear and nonlinear optical (NLO) properties remains a formidable challenge. Herein, we present a novel approach to optimizing these properties in KBe2BO3F2 (KBBF)‐analog crystals via functional group self‐polymerization. This strategy led to the synthesis of two new optical crystals: noncentrosymmetric CsAs2O3Br and centrosymmetric CsAs4O6Br. By incorporating highly optically active [AsO3]3− units into the classical 2D [Be2BO3F]∞− framework, we facilitated the self‐assembly of [As2O3]∞ layers, forming a densely packed and highly ordered structure that enhances macroscopic optical activity. CsAs2O3Br exhibited an extraordinary second‐harmonic generation (SHG) response, 20.5 times stronger than KH2PO4 (KDP), while CsAs4O6Br demonstrated exceptional birefringence (0.26 at 546 nm), setting new performance benchmarks among KBBF analogs. Theoretical analyses reveal that these superior properties arise from the efficient alignment and high density of self‐polymerized functional units. This work represents a significant advancement in the design of high‐performance UV NLO materials, particularly for fourth‐harmonic generation, and paves the way for future innovations in photonic technologies, including solar‐blind UV laser systems and advanced photonic devices.

Polarization-Dependent Plasmon-Induced Doping and Strain Effects in MoS2 Monolayers on Gold Nanostructures.

Monolayers of transition-metal dichalcogenides, such as MoS2, have attracted significant attention for their exceptional electronic and optical properties, positioning them as ideal candidates for advanced optoelectronic applications. Despite their strong excitonic effects, the atomic-scale thickness of these materials limits their light absorption efficiency, necessitating innovative strategies to enhance light-matter interactions. Plasmonic nanostructures offer a promising solution to overcome those challenges by amplifying the electromagnetic field and also introducing other mechanisms, such as hot electron injection. In this study, we investigate the vibrational and optical properties of MoS2 monolayer deposited on gold substrates and gratings, emphasizing the role of strain and plasmonic effects using conventional spectroscopic techniques. Our results reveal significant biaxial strain in the supported regions and a uniaxial strain gradient in the suspended ones, showing a strain-induced exciton and carrier funneling effect toward the center of the nanogaps. Moreover, we observed an additional polarization-dependent doping mechanism in the suspended regions. This effect was attributed to localized surface plasmons generated within the slits, as confirmed by numerical simulations, which may decay nonradiatively into hot electrons and be injected into the monolayer. Photoluminescence measurements further demonstrated a polarization-dependent trion-to-A exciton intensity ratio, supporting the hypothesis of additional plasmon-induced doping. These findings provide a comprehensive understanding of the strain-mediated funneling effects and plasmonic interactions in hybrid MoS2/Au nanostructures, offering valuable insights for developing high-efficiency photonic devices and quantum technologies, including polarization-sensitive detectors and excitonic circuits.

The Precise Synthesis of Ultradense Bottlebrush Polymers Unearths Unique Trends in Lyotropic Ordering.

Biomacromolecular networks with multiscale fibrillar structures are characterized by exceptional mechanical properties, making them attractive architectures for synthetic materials. However, there is a dearth of synthetic polymeric building blocks capable of forming similarly structured networks. Bottlebrush polymers (BBPs) are anisotropic graft polymers with the potential to mimic and replace biomacromolecules such as tropocollagen for the fabrication of synthetic fibrillar networks; however, a longstanding limitation of BBPs has been the lack of rigidity necessary to access the lyotropic ordering that underpins the formation of collagenous networks. While the correlation between BBP rigidity and grafting density is well established, synthetic approaches to rigidify BBPs by increased grafting density are underdeveloped. To address this gap in synthetic capability, we report the synthesis of novel macroinitiators that provide well-defined BBPs with an unprecedentedly high grafting density. A suite of light scattering techniques are used to correlate macromolecular rigidity with grafting architecture and density and demonstrate for the first time that poly(norbornene) BBPs exhibit long-range lyotropic ordering as a result of their rodlike character. Specifically, the newly reported ultradensely grafted structures, preparable on multigram scale, form hexagonal arrays while conventional BBPs do not, despite showing long-range spatial correlations. These results implicate the central role of density and entanglement in the solution phase assembly of BBPs and provide new fundamental insight that is broadly relevant to the fabrication and performance of BBP-derived materials, spanning biomedical research to photonic materials and thermal management technologies. Furthermore, these newly reported liquid crystalline BBPs provide a structural template to explore the untapped potential of the bottom-up assembly of semiflexible networks and are ultimately intended to provide a modular route to hierarchically structured biomimetic materials.