Light Source Research Articles

Metal Doping Enabling Defective CoMo-Layered Double Hydroxide Nanosheets as Highly Efficient Photosensitizers for NIR-II Photodynamic Cancer Therapy.

Photodynamic therapy (PDT) is attracting widespread attention as a promising strategy for tumor treatment. However, the efficacy of PDT is severely limited by the insufficient tissue penetration depth of the light source and low reactive oxygen species (ROS) generation efficiency. Herein, the metal doping strategy is reported to construct a series of defect-rich M-doped amorphous CoMo-layered double hydroxide (a-M-CoMo-LDH, M = Mn, Cu, Al, Ni, Mg, Zn) photosensitizers (PSs) for NIR-II PDT. Especially, M-doped CoMo-LDH nanosheets are synthesized through a simple hydrothermal method and then etched by acid treatment to prepare defect-rich a-M-CoMo-LDH nanosheets. Under NIR-II 1270 nm laser irradiation, the defect-rich a-Zn-CoMo-LDH nanosheets exhibit the optimal PDT performance compared with other a-M-CoMo-LDH nanosheets, and also possess much higher ROS production activity (3.9 times) than that of the pristine a-CoMo-LDH, with a singlet oxygen quantum yield up to 1.86, which is the highest among all the reported PSs. After polyethylene glycol (PEG) modification, the a-Zn-CoMo-LDH-PEG nanosheets can function as an effective inorganic PS for PDT, effectively inducing cell apoptosis in vitro and eradicating tumors in vivo. Notably, transcriptome sequencing analysis and further molecular validation highlight the critical role of the apoptotic/p53/AMPK/oxidative phosphorylation signaling pathways in a-Zn-CoMo-LDH-PEG-induced cancer cell apoptosis.

NIM diffuse reflectance scale to super black level (0.0001)

Abstract The realization of the super black level diffuse reflectance scale of the National Institute of Metrology (NIM, China) is presented. Two facilities were used to achieve the reflectance scale under 0/d condition covering 0.0001-1.0, the first one based on the supercontinuum light source was used to realize the diffuse scale in the wavelength range 500 nm to 2000 nm, while the other one based on QCL was applied for the mid infrared range from 7.5 μm to 10.6 μm. The relative expanded uncertainty(coverage factor k = 2) of the reflectance scale was evaluated to be from 2.2 % to 8.4 % varying with range and wavelength in visible band to near infrared band while the reflectance is down to 0.0001. In the mid infrared band, the uncertainty of the reflectance scale was up to 8.8% while reflectance is 0.001, and up to 42.4% while reflectance is down to 0.0001. This low reflectance level scale can meet the calibration requirement of super black material or system such as carbon nanotube or blackbody.

Pure rotational Raman lidar for accurate profiling of atmospheric temperature and aerosol/cloud backscatter coefficients

We have created a pure rotational Raman (PRR) lidar for round-the-clock and large-height-range quantitatively-physical measurements of atmospheric temperature profiles. A seeded frequency-doubled Nd:YAG laser is utilized as the light source. It has a typical power of ∼18 W and a pulse repetition rate of 30 Hz. The lidar uses a 0.3-m-diameter receiver and a 1.0-m-diameter receiver together. Each receiver contains a state-of-the-art three-channel polychromator that extracts respectively two individual Stokes N2 PRR lines with rotational quantum numbers J = 4 and 14, as well as a Rayleigh/Mie backscatter signal. The temperature profiles are derived from the strict analytical expression of temperature in terms of the ratio of the two PRR line signals without calibration. Furthermore, a strict analytical expression has been established to derive the aerosol/cloud backscatter coefficient profiles without assumptions on the lidar ratio. The lidar provides a rigorous and effective methodology for accurate profile measurements of the atmospheric temperature and optical properties of aerosol/cloud. Observational examples and statistics obtained at a subtropical site have demonstrated the high measurement accuracies, large measurement altitude range, good range/time resolution, and unprecedented daytime measurement capability of this single-line-extracted PRR lidar.

Recent Results from the FASER Experiment at the LHC

The ForwArd Search ExpeRiment (FASER), is an LHC experiment that aims to: (1) detect and study TeV-energy neutrinos, the most energetic neutrinos ever detected from a humanmade source and (2) search for new light and very weakly interacting particles. The FASER detector is located 480 m downstream of the ATLAS p-p interaction point, along the beam collision axis. FASER was designed, constructed, installed, and commissioned during 2019–2022 and has been taking physics data since the start of LHC Run 3 in July 2022. Recently, FASER reported the first measurement of ve and vμ interaction cross sections at the LHC with its sub-detector FASERv , FASER’s emulsion detector, first results on Axion-Like Particles at FASER and dark photons limits. These results will be reported in this article.

Simulation and optimization of strained GeSn laser with SiN-induced stress

By modifying Germanium (Ge) material, direct bandgap emission can be achieved, improving light emission efficiency. This paper proposes a strain-engineered GeSn laser based on SiN stress. The stress distribution within the device and its optoelectronic characteristics were analyzed through simulation. The laser is predicted to emit light at a wavelength of approximately 2252 nm, with a threshold current density around 220 kA/cm2. By introducing a multi-quantum well (MQW) structure, the threshold current density is reduced to about 90 kA/cm2. The work in this paper provides a feasible technical solution for the design of efficient silicon-based light sources.

Photoisomerization Dynamics of 2-[(E)-(4-fluorophenyl)diazenyl]-1H-imidazole: A Theoretical and Experimental Insight

This study investigates the photoresponsive behavior of substituted azobenzenes with a specific focus on their nonlinear optical response. This study suggests that azoimidazole substitution is a better alternative to azobenzene derivatives for nonlinear optical responses. The synthesis, characterization, photophysical property and isomerization pathway of 2-[(E)-(4-fluorophenyl)diazenyl]-1H-imidazole (E-2g) are presented as an optical limiter through a comprehensive blend of experimental and theoretical approaches. Notably, E-2g exhibited a lower energy barrier than reported azobenzenes. The trans-to-cis photostationary state was reached in 75 min, while the cis-to-trans state was achieved in 60 min at 354 nm. The study further explores the photoisomerization pathway of E-2g, highlighting its nonlinear absorption, which has a nonlinear absorption coefficient ([Formula: see text]) of 8.8 × 10–11 m/W at 20 [Formula: see text]J, as determined by Z-scan measurements. The results suggest that E-2g exhibits significant nonlinear absorption characteristics, which helps in applications requiring protection from intense light sources.

Far‐red light acclimation in Phaeophila dendroides (Ulvales, Ulvophyceae) isolated from a coral skeleton

SUMMARYThe light environment within a coral skeleton is rich in far‐red light (FRL) but lacks photosynthetically active radiation. Nevertheless, various algal species have been detected in these photosynthetically severe environments. We isolated the filamentous green alga Phaeophila dendroides strain Sa‐1 (Ulvales, Ulvophyceae) from a coral skeleton (Porites sp.) off Sesoko Island, Okinawa, Japan. This is the first Phaeophila strain to have been isolated from a coral skeleton. The strain grew under far‐red light‐emitting diodes (FRL‐LED) as a sole light source, as well as under white light, demonstrating that it can acclimate to FRL. We experimentally determined that cells grown under FRL‐LED alone absorbed the light by red‐shifted chlorophyll a associating with newly induced or modified light‐harvesting antenna complexes. This ability allows P. dendroides strain Sa‐1 to inhabit environments where FRL is dominant, such as the interior of coral skeletons or the surface of seaweed.

Self-healing actuatable electroluminescent fibres

Alternating-current electroluminescent fibres are promising candidates as light sources for smart textiles and soft machines. However, physical damage from daily use causes device deterioration or failure, making self-healable electroluminescent fibres attractive. In addition, soft robots could benefit from light-emitting combined with magnetically actuated functions. Here, we present a self-healing and actuatable Scalable Hydrogel-clad Ionotronic Nickel-core Electroluminescent (SHINE) fibre which achieves a record luminance of 1068 cd × m−2 at 5.7 V × μm−1. The SHINE fibre can self-heal across all constituent layers after being severed, recovering 98.6% of pristine luminance and maintaining for over 10 months. SHINE fibre is also magnetically actuatable due to the ferromagnetic nickel electrode core, enabling a soft robotic fibre with omnidirectional actuation and electro-luminescence. Our approach to this multifunctional fibre broadens the design of fibre electronics and fibre robots, with applications in interactive displays and damage-resilient navigation.

DABCO‐Mediated Photoelectrochemical Three‐Component Sulfonocyclization of 3‐Aza‐1,5‐dienes

Comprehensive SummaryHerein, we report a rare example of three‐component net‐oxidative sulfonylation of a SO2 surrogate with an oxidatively activated radical precursor under mild and metal‐ and external‐oxidant‐free conditions. The mildness and sustainability of the reaction are enabled by photoelectrocatalysis, and 3‐aza‐1,5‐dienes, organotrifluoroborates and 1,4‐diazabicyclo[2.2.2]octane bis(sulfur dioxide) adduct (DABSO) undergo sulfonylative cyclization to afford sulfono 4‐pyrrolin‐2‐ones in an atom‐economical manner with a broad substrate scope and good functional‐group tolerance. The protocol is amenable to the late‐stage diversification of complex molecular architectures as well as the gram‐scale synthesis. Sunlight could be used as the light source, and the reaction could be conducted in an all‐solar mode using a commercially available photovoltaic panel to generate electricity in situ. Mechanistic studies reveal that the in situ generated 1,4‐diazabicyclo[2.2.2]octane (DABCO), which was generally innocent in previous reactions, functions as an electron shuttle between the photocatalytic cycle and the reactants.

An Assessment of Strength Characteristics of Transparent Concrete in Pavement

This study explores the potential of transparent concrete for use in roadway applications, focusing on its ability to transmit light through the incorporation of Plastic Optical Fibres (POFs) within the concrete matrix and evaluating both its mechanical strength and its light transmission capabilities. This material can be applied to various road elements, such as surface illumination, signage, roadblocks, medians, curbs, and areas with changing geometry. The light transmission performance was evaluated using voltage, light sources, and Light-Dependent Resistors (LDRs). A comparative analysis was performed between samples with varying POF content and spacing and traditional concrete. The findings reveal that compressive and flexural strengths remain largely unaffected by the inclusion of POFs up to 1.5% by weight, beyond which a decrease in strength is observed. Additionally, the light transmission efficiency improves significantly with an increase in the POF volume ratios.

Autonomous phototaxis of hydrogel swimmers

The design of synthetic soft matter capable of emulating the complex behaviors of living organisms, such as sensing and adapting to their environment, remains an important challenge in developing biomimetic materials. Functionalized hydrogels are ideal candidates for such materials since they are highly responsive to their environment and can be operated in water. In this work, we investigate a hybrid bonding hydrogel composed of peptide amphiphile supramolecular nanofibers covalently attached to a photoresponsive network, in which high-aspect-ratio ferromagnetic nanowires are aligned along the length of the sample, designed to swim under oscillating magnetic fields. This hybrid hydrogel swimmer can autonomously swim toward a light source by utilizing photoinduced interactions between supramolecular and covalent networks reminiscent of phototactic swimming in living systems. Using a combination of experimental techniques and a continuum model incorporating photochemistry, magnetoelasticity, and hydrodynamics, we explain the swimming mechanism and predict phototactic behavior. Our work highlights the potential role of hybrid bonding polymers, which leverage the interplay between supramolecular assemblies and covalent networks. We demonstrate how these polymers can be tailored to react dynamically to their environment, paving the way for developing intelligent and autonomous robotic systems.

Record-high power, low phase noise synchronously-pumped optical parametric oscillator tunable from 2.7 to 4.7 μm

Within the domain of optical frequency comb systems operating in the mid-infrared region, extensive exploration has been undertaken regarding critical parameters, such as stabilization, coherence, or spectral tunability. Despite this, certain essential parameters remain inadequately addressed, particularly concerning light source stability at high average powers. This study explores stability limitations of an optical parametric oscillator system when scaling to several watts of average power of the idler. Notably, the highest average power reported in the 3–5 μm region, reaching 10.3 W for the idler output at 3.1 μm, is achieved. Additionally, we analyze the phase noise and beam quality of both idler and signal beams and identify the onset of higher order modes as limiting for stability at high-power operation. Finally, we estimate the free-running optical linewidth of our idler beam to be ∼300 kHz, undermining the high passive temporal stability of our source. These findings represent a significant advancement toward the realization of highly stable high-power optical frequency combs in the mid-infrared region, thereby facilitating applications previously constrained by light source average powers and quality limitations.

Adjustable enhanced photoluminescence in whispering-gallery-mode microdisk arrays

Microdisk with whispering gallery modes (WGMs) is a prominent candidate for the studies of fundamental properties of cavity quantum electrodynamics (CQED) and the explorations of on-chip light sources or sensors. Here, we report on the significant array effect on WGMs in SiGe microdisk arrays. Systematic photoluminescence spectra demonstrate an optimal microdisk interval associated with wavelength and the array symmetry dependence for each WGM. The enhancement factor of WGM can be increased by over 270% and 120% with the modification of microdisk interval and array symmetry, respectively. Moreover, a single dominant WGM can be achieved in the array of microdisks with intentionally designed nanoholes. The intrinsic mechanism of the array effect is disclosed in terms of the intradisk light field distribution and the interdisk coupling. Our results provide strategies for the substantial enhancement of desired WGM in microdisk array to comprehensively understand CQED and fabricate innovative optoelectronic devices.

Highly Efficient and Thermally Stable Ultra-Broadband NIR-II Emtting Li(Ga, Al)5O8:Cr3+, Ni2+ Phosphors for Spectroscopy Analysis.

Near-infrared (NIR) spectroscopy has diverse applications across various fields, such as the detection of food components and pesticide residues, early diagnosis, and treatment of cancer. In this work, a series of optimized LiAl5-xGaxO8:0.1Ni2+ (x = 0-5) ultrabroadband NIR-II luminescent systems are developed. The density functional theory (DFT) calculations, time-resolved photoluminescence (TRPL) spectroscopy, and 77 K PL spectra demonstrate that the substitution of Ga3+ for Al3+ creates more favorable sites for Ni2+ luminescence and enhances structural orderliness while reducing the number of luminescent centers. This leads to a red shift in the emission peak from 1177 to 1252 nm with a 14-fold increase in luminescence intensity. At 375 K, thermal stability increases from 81% (x = 0) to 90% (x = 5) compared to 300 K. Subsequent co-doping with Cr3+ results in an excitation peak with a red shift into the blue-violet region (420 nm), accompanied by a notable enhancement in absorption efficiency (AE) and an increase in external quantum efficiency (EQE) from 4% to 62%. Finally, the potential application of the prepared phosphors in both qualitative and quantitative analysis of organic compounds is demonstrated, which will offer new insights for the design and synthesis of ultrabroadband NIR-II light sources.

Chromium Isotope Fractionation During the Removal of Hexavalent Chromium by Oak-based Biochar

Chromium, especially in its hexavalent form (Cr(VI)), poses significant health risks due to its carcinogenic properties. Emerging research suggests that biochar, a carbon-rich material derived from biomass pyrolysis, holds promise as an effective and sustainable solution for Cr(VI) remediation. Biochar's unique physicochemical properties, such as its high surface area, porous structure, and functional groups, contribute to its exceptional adsorption capacity for metals. In a series of batch experiments with varying durations, an oak-based biochar was exposed to a 48 mg∙L⁻1 Cr(VI) solution. The results demonstrate that the biochar effectively removed 99% of the Cr(VI) after 100 hours, with a removal capacity greater than 5 mg∙g⁻1. Fourier transform infrared (FTIR) spectroscopy suggests that the removal of Cr(VI) involved aliphatic and aromatic C-H bonds. X-ray photoelectron spectroscopy (XPS) also indicated the role of aliphatic groups in the removal process and suggested the involvement of carbonyl groups. XPS analysis also detected both Cr(III) and Cr(VI) on the surface of the biochar, indicating the occurrence of reduction and sorption processes. The presence of Cr(III) and Cr(VI) was further confirmed at the Canadian Light Source (CLS) synchrotron facility using X-ray absorption near edge structure (XANES) spectroscopy. Cr isotope analysis showed an increase in δ⁵³Cr as the concentration of Cr in solution decreased, indicating Cr(VI) reduction. The isotope data followed a Rayleigh curve with a kinetic fractionation ε53Cr of -1.33 ‰, highlighting that Cr stable isotopes can effectively be used as an indicator of biochar-Cr reactions.

Polarization entanglement enabled by orthogonally stacked van der Waals NbOCl2 crystals

Polarization entanglement holds significant importance for photonic quantum technologies. Recently emerging subwavelength nonlinear quantum light sources, e.g., GaP and LiNbO3 thin films, benefiting from the relaxed phase-matching constraints and volume confinement, have shown intriguing properties, such as high-dimensional hyperentanglement and robust entanglement anti-degradation. Van der Waals (vdW) NbOCl2 crystal, with strong optical nonlinearities, has emerged as a potential candidate for ultrathin quantum light sources. However, polarization entanglement is inaccessible in the NbOCl2 crystal due to its unfavorable nonlinear susceptibility tensor. Here, by leveraging the twist-stacking degree of freedom inherently in vdW systems, we showcase the preparation of polarization entanglement and quantum Bell states.

Highly efficient tunable mid-infrared luminescence achieved by crystal field modulation of CsPb1-xHoxBr3 halide perovskite AlF3-based fluoride glass

Mid-infrared (MIR) light sources have gained significant importance across various applications in spectroscopy, sensing, astronomy, communications and medical surgery. The diverse spectral characteristics of rare earth ions, particularly lanthanide ions, stemming from their distinctive 4f intershell transitions, offer a multitude of potential transitions spanning the UV-visible-infrared spectrum. Despite recent advancements in MIR gain luminescence, the investigation of tunable MIR luminescence mechanisms remains a major technical challenge. Herein, an effective mechanism to modulate the local crystal field of rare earth ions by altering its crystal structure has been revealed, resulting in tunable broad-spectrum emission in the MIR luminescence range of 2800-3000 nm and multi-peak emission in the near-infrared band of Ho3+. Notably, the local crystal field of Ho3+ is adjusted by manipulating the lattice symmetry of CsPb1-xHoxBr3 perovskite through the incorporation of fluoride glass reticulation to control the crystal size of the perovskite and thereby modify the lattice symmetry of CsPb1-xHoxBr3 perovskite. The energy level transition of Ho3+ is influenced by adjusting the crystal field asymmetry, resulting in the splitting of the 5I6 energy level depending on the crystal field. This cleavage affects the transitions from the 5I5 level to 5I6 at 1480 nm and from 5I6 to 5I7 at 2880 nm. As 5I6 acts as the common upper level for the two emission peaks, the infrared peaks at 1480 nm and 2880 nm widen and develop into a dual-peak emission phenomenon. The infrared luminescence produced aligns closely with the distinctive infrared absorption peaks of carbon dioxide, leading to the development of a convenient, high-precision device for monitoring of CO2 concentration in hydrogen energy in real time. These findings are anticipated to pave the way for extensive utilization of novel tunable MIR luminescence.

Technical Report A light touch; Reviewing the relative effectiveness of light sources and physical/chemical techniques for fingermark retrieval in casework

This study reviewed the efficacy of non-contact light source examinations of serious crime scenes using ultraviolet A (UVA) light, bespoke white light and lasers, compared with subsequent powdering or chemical enhancements. Twenty-six examinations of serious crime scenes or motor vehicles were analysed, from which 655 areas of retrieved fingermark or friction ridge detail11Friction Ridge Detail (FRD) relates to deposits made from fingers, phalange, palm or plantar regions. where reported on. It was found that undertaking a light source examination revealed equivalent numbers of marks to aluminium powder and chemical enhancements, with only a 4% duplication rate between optical and physical/chemical techniques suggesting that both approaches are supplementary and should be used sequentially to each other.

Controllable fabrication of the luminescent photocatalytic material AgB/SMSO for application in cement: Optimization of doping strategies and all-weather degradation of pollutants

This paper presents an innovative luminescent photocatalytic material, Ag3PO4/BiVO4/Sr2MgSi2O7:(Eu2+, Dy3+) (AgB/SMSO), which overcomes a pivotal limitation of photocatalysts—dependence on a light source—and effectively remediates pollutants and augments cement-based composite properties. The efficient carrier separation facilitated by Ag3PO4, in conjunction with the broad spectral response of BiVO4, enables AgB/SMSO to harness the internal luminescent properties of SMSO as a persistent light source, achieving continuous degradation of pollutants, which reveals the exceptional afterglow characteristics and photocatalytic activity of AgB/SMSO. At a 1:1:40 ratio, AgB/SMSO maintained its catalytic efficacy for over 8 h in the dark (methylene blue degradation rate of 70.43%), surpassing the 3-hour limit of current luminescent photocatalysts. Furthermore, the impact of integrating AgB/SMSO with cement on early-stage cement hydration, morphology, and micromechanical properties was comprehensively assessed. Ultimately, the overall photocatalytic capability of the derived AgB/SMSO cement-based composites was evaluated through experiments, revealing the synergistic mechanisms involved. This study not only enriches the theoretical understanding of photocatalysis but also provides a robust technical foundation for the innovation of environmentally friendly building materials and the advancement of sustainable urban development.

Reconfigurable MISO-VLC via Joint Light Source Identification and Localization Using a Receiver With Spatial LCD Filter

Reconfigurable MISO-VLC via Joint Light Source Identification and Localization Using a Receiver With Spatial LCD Filter