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[Display omitted] Two-dimensional (2D) layered group-IV monochalcogenides with large surface-to-volume ratio and high surface activity make that their structural and optoelectronic properties are sensitive to air oxidation. Here, we report the utilization of oxidation-induced gradient doping to modulate electronic structures and optoelectronic properties of 2D group-IV monochalcogenides by using SnS nanoplates grown by physical vapor deposition as a model system. By a precise control of oxidation time and temperature, the structural transition from SnS to SnSO x could be driven by the layer-by-layer oxygen doping and intercalation. The resulting SnSO x with a graded narrowing bandgap exhibits the enhanced optical absorption and photocurrent, leading to the fabricated SnSO x photodetector with remarkable photoresponsivity and fast response speed (<64 μs) at a broadband spectrum range of 520–1550 nm. The peak responsivity (7294 A/W) and detectivity (9.54 × 109 Jones) of SnSO x device are at least two orders of magnitude larger than those of SnS photodetector. Moreover, its photodetection performance can be competed with state-of-the-art of 2D materials-based photodetectors. This work suggests that the air oxidation could be utilized as an efficient strategy to engineer the electronic and optical properties of SnS and other 2D group-IV monochalcogenides for the development of high-performance broadband photodetectors. [ABSTRACT FROM AUTHOR]

Implementing on-chip non-volatile optical memories has long been an actively pursued goal, promising significant enhancements in the capability and energy efficiency of photonic integrated circuits. Here, we demonstrate an non-volatile optical memory exclusively using the most common semiconductor material, silicon. By manipulating the photon avalanche effect, we introduce a trapping effect at the silicon-silicon oxide interface, which in turn demonstrates a non-volatile reprogrammable optical memory cell with a record-high 4-bit encoding, robust retention and endurance. This silicon avalanche-induced trapping memory provides a distinctively cost-efficient and high-reliability route to realize optical data storage in standard silicon foundry processes. We demonstrate its applications in trimming in optical interconnects and in-memory computing. Our in-memory computing test case reduces energy consumption by approximately 83% compared to conventional optical approaches. On-chip non-volatile optical memories significantly enhance the functionality and energy efficiency of photonic integrated circuits. In this study, the authors present an all-silicon optical memory utilizing the photon avalanche-induced trapping effect, providing a solution readily compatible with silicon photonics. [ABSTRACT FROM AUTHOR]

Position-sensitive detectors based on the lateral photovoltaic effect have been widely used in optical engineering for the measurement of position, distance, and angles. However, self-powered ultraviolet position-sensitive detectors with high sensitivity and fast response are still lacking due to the difficulty associated with the fabrication of p-type wide bandgap semiconductors, which hinders their further design and enhancement. Here, the influence of band structures and interfacial transport properties on the performance of self-powered ultraviolet position-sensitive detectors based on PrNiO3/Nb:SrTiO3p–n junctions is systematically investigated. Large position sensitivity and fast relaxation time of the lateral photovoltaic effect were observed up to 400 K in the perovskite-based ultraviolet position-sensitive detectors. Hall effect measurements revealed that the transport of photoexcited carriers occurs mainly through the interface of the PrNiO3/Nb:SrTiO3 junctions, resulting in a fast response and a stable photovoltaic effect. This study presents insights and avenues for designing self-powered perovskite oxide ultraviolet position-sensitive detectors with enhanced photoelectric performance. [ABSTRACT FROM AUTHOR]

Highlights: Methods for creating the local deformation in two-dimensional transition metal dichalcogenides (2D TMDCs) are introduced. Modulations of local strain on their optical properties and excitonic behaviors are discussed. Quantum emitters based on strained 2D TMDCs and other applications are presented. Two-dimensional transition metal dichalcogenides (2D TMDCs) have received considerable attention in local strain engineering due to their extraordinary mechanical flexibility, electonic structure, and optical properties. The strain-induced out-of-plane deformations in 2D TMDCs lead to diverse excitonic behaviors and versatile modulations in optical properties, paving the way for the development of advanced quantum technologies, flexible optoelectronic materials, and straintronic devices. Research on local strain engineering on 2D TMDCs has been delved into fabrication techniques, electronic state variations, and quantum optical applications. This review begins by summarizing the state-of-the-art methods for introducing local strain into 2D TMDCs, followed by an exploration of the impact of local strain engineering on optical properties. The intriguing phenomena resulting from local strain, such as exciton funnelling and anti-funnelling, are also discussed. We then shift the focus to the application of locally strained 2D TMDCs as quantum emitters, with various strategies outlined for modulating the properties of TMDC-based quantum emitters. Finally, we discuss the remaining questions in this field and provide an outlook on the future of local strain engineering on 2D TMDCs. [ABSTRACT FROM AUTHOR]

We report efficient generation of ultrashort laser pulses in the deep ultraviolet (DUV) from a quasi-phase-matched (QPM) optical parametric oscillator (OPO) based on a periodically poled KTP (PPKTP) crystal. Up-conversion through frequency-doubling of the signal pulses (2ωS) and sum-frequency generation between the pump and signal pulses (ωP + ωS) produces femtosecond pulses in the green and in the blue, respectively. A third-order QPM is responsible for the green-pulse generation and a fifth-order QPM for the blue. The cavity mirrors have two high-reflection bands, which support the oscillation of the OPO signal (ωS) in the near infrared and the sum-frequency generation of ωP + ωS in the blue, respectively. The interaction between the blue and green pulses enables further cascading by a sum-frequency generation process, producing the DUV pulses. Cavity-length detuning facilitates the large tuning range of the DUV generation. [ABSTRACT FROM AUTHOR]

Atomically thin group-VI transition metal dichalcogenides have garnered significant attention for potential electronic and optoelectronic applications. These two-dimensional (2D) monolayer materials exhibit noteworthy features driven by the inversion symmetry and the spin-orbit coupling (SOC) effects. Through Floquet engineering, the impact of SOC on the Floquet oscillations in these 2D materials has been elucidated using theoretical and numerical methods. The study reveals the substantial effect of SOC coupling on the Rabi frequency and the Bloch-Siegert shift phenomenon. Furthermore, it becomes evident that SOC plays a pivotal role in the quantum mechanical collapse and revival phenomenon within the Floquet framework. The observed offset Floquet oscillations are solely contributed by the gap term and the spin-orbit interaction parameter. In the zero-photon limit, a corresponding phenomenon called as vacuum Floquet oscillation also occurs. [ABSTRACT FROM AUTHOR]

Neuromorphic engineering has emerged as a promising avenue for developing brain-inspired computational systems. However, conventional electronic AI-based processors often encounter challenges related to processing speed and thermal dissipation. As an alternative, optical implementations of such processors have been proposed, capitalizing on the intrinsic information-processing capabilities of light. Among the various Optical Neural Networks (ONNs) explored within the realm of optical neuromorphic engineering, Spiking Neural Networks (SNNs) have exhibited notable success in emulating the computational principles of the human brain. The event-based spiking nature of optical SNNs offers capabilities in low-power operation, speed, temporal processing, analog computing, and hardware efficiency that are difficult or impossible to match with other ONN types. In this work, we introduce the pioneering Free-space Optical Deep Spiking Convolutional Neural Network (OSCNN), a novel approach inspired by the computational model of the human eye. Our OSCNN leverages free-space optics to enhance power efficiency and processing speed while maintaining high accuracy in pattern detection. Specifically, our model employs Gabor filters in the initial layer for effective feature extraction, and utilizes optical components such as Intensity-to-Delay conversion and a synchronizer, designed using readily available optical components. The OSCNN was rigorously tested on benchmark datasets, including MNIST, ETH80, and Caltech, demonstrating competitive classification accuracy. Our comparative analysis reveals that the OSCNN consumes only 1.6 W of power with a processing speed of 2.44 ms, significantly outperforming conventional electronic CNNs on GPUs, which typically consume 150-300 W with processing speeds of 1-5 ms, and competing favorably with other free-space ONNs. Our contributions include addressing several key challenges in optical neural network implementation. To ensure nanometer-scale precision in component alignment, we propose advanced micro-positioning systems and active feedback control mechanisms. To enhance signal integrity, we employ high-quality optical components, error correction algorithms, adaptive optics, and noise-resistant coding schemes. The integration of optical and electronic components is optimized through the design of high-speed opto-electronic converters, custom integrated circuits, and advanced packaging techniques. Moreover, we utilize highly efficient, compact semiconductor laser diodes and develop novel cooling strategies to minimize power consumption and footprint. [ABSTRACT FROM AUTHOR]

Over the past few decades, significant progress has been made in the development of nanomaterials, including carbon nanotubes, boron nanoclusters, boron nanowires, boron nanotubes and many more. These nanomaterial have revolutionized the twenty first century, finding applications in vital domains such as defense, security, electronics, optical engineering, and medicine. Among these nanomaterials, boron nanomaterials hold great importance in nanotechnology due to their exceptional electrical and mechanical properties. The face index of graph is a metric that plays a crucial role in graph theory, providing valuable insights into the structural properties of a graph. It sheds light on graph's connectivity and planarity, allowing researchers to analyze and understand its characteristics more effectively. In this article, we calculated the recently introduced face index for three significant classes of boron nanotubes: tri-hexagonal nanotube, tri-angular boron nanotube and boron-α nanotubes. [ABSTRACT FROM AUTHOR]

Tunable optical devices are of paramount importance in modern optical engineering, offering the flexibility to dynamically adjust key optical parameters, thus enhancing functionality and adaptability. In this study, a fresh approach is presented to achieve on‐demand, spatially tunable optical properties using organic mixed ion‐electron conductors, which can be produced using large‐scale, cost‐effective technologies. It is demonstrated how, by exploiting, the spatial modulation of the bulk electronic conductance of PEDOT:PSS through an organic electrochemical transistor configuration, we can create a spatially tunable broadband gradient index profile with multiple degrees of freedom. These findings introduce a new class of tunable graded index media, which hold potential for a wide range of applications that span from optical interconnections to multi‐focal optical devices. [ABSTRACT FROM AUTHOR]

The efficiency of solar‐fuel conversion in photoelectrochemical (PEC) systems is hindered by significant losses of photons and photocarriers within the photoelectrodes. This study introduces an innovative ITO@In2S3 core‐shell nanowire structure designed to overcome these challenges through cutting‐edge materials engineering and sophisticated simulation techniques. Optical modeling and finite element simulations highlight the conflict between photocarrier generation and collection in planar In2S3 thin films and demonstrate how the core‐shell nanowire geometry can significantly enhance light absorption. The developed ITO@In2S3 nanowire photoanodes achieve a photocurrent of 11.3 mA cm−2 at 1.23 V versus RHE, which is nearly five times greater than that of planar ITO/In2S3 thin films. Characterization techniques, including UV–vis absorption and charge separation efficiency measurements, confirm the enhanced light absorption and improved carrier collection facilitated by broadening the optical absorption range and reducing carrier transport distances. This research not only deepens the understanding of the dynamics within thin‐film photoelectrodes but also paves the way for the development of more efficient technologies for solar fuel conversion. [ABSTRACT FROM AUTHOR]

Hybrid Power Line Communication (PLC)—Visible Light Communication (VLC) (HPV) systems are emerging as a cost-effective and efficient solution to enable high-speed communication. However, the random connection of electrical devices to the power line introduces Impulsive Noise (IN) in the PLC channel, which significantly degrades the Bit Error Rate (BER) of HPV systems. Existing studies have primarily focused on mitigating IN by setting the IN signals to either zero or a threshold value after the PLC stage. While previous studies have progressed in reducing noise, they have neglected the critical aspect of restoring the corrupted information signal that leads to data loss and increased BER. This study offers a novel Asymmetrical Recovery Filter (ARF) method to address the IN problem in HPV systems using Asymmetrically-Clipped Optical Orthogonal Frequency Division Multiplexing (ACO-OFDM). The ARF method not only suppresses the IN but also recovers impulsively corrupted data without causing signal loss, significantly enhancing the overall system BER performance. By leveraging ACO-OFDM's naturally occurring different forms of identical signals, the ARF method avoids additional bandwidth usage during recovery and achieves this with a low-computational algorithm. The ARF method's robustness is demonstrated through extensive simulations in both IN-free and IN-contaminated scenarios, outperforming existing signal lossy IN suppression methods. [ABSTRACT FROM AUTHOR]

Signal beam combiners play a pivotal role in enhancing the output power of fiber lasers, which have wide-ranging applications from industrial processing to medical and military uses. This paper explores the influence of fiber twist angle and non-uniform symmetric arrangement on the performance of 19 × 1 fiber signal combiners. A simulation model was developed to analyze the impact of these parameters under adiabatic tapering conditions and the principle of brightness conservation. The model allowed for a systematic investigation of how varying twist angles and non-uniform spacings affect the combiner's performance metrics, such as transmission efficiency and beam quality. The study found that an optimal balance between high transmission efficiency (up to 98.5%) and good beam quality (minimum M2 factor of 1.06) can be achieved when the twist angle is kept below 60° and the non-uniform spacing is maintained within 10–30 μm. These conditions ensure minimal degradation of the beam quality while maximizing the transmission efficiency of the combiner. These findings offer valuable insights into the optimization of signal combiner design, which is critical for advancing high-power fiber laser systems. By carefully controlling the fiber twist angle and non-uniform spacing, designers can achieve superior performance in fiber laser applications, thereby enhancing the overall efficiency and reliability of these systems. This research contributes to the broader field of optical engineering by providing a deeper understanding of the underlying principles that govern the performance of signal combiners. [ABSTRACT FROM AUTHOR]

In the field of tissue engineering, achieving precise spatiotemporal control over engineered cells is critical for sculpting functional 2D cell cultures into intricate morphological shapes. In this study, we engineer light-responsive mammalian cells and target them with dynamic light patterns to realize 2D cell culture patterning control. To achieve this, we developed μPatternScope (μPS), a modular framework for software-controlled projection of high-resolution light patterns onto microscope samples. μPS comprises hardware and software suite governing pattern projection and microscope maneuvers. Together with a 2D culture of the engineered cells, we utilize μPS for controlled spatiotemporal induction of apoptosis to generate desired 2D shapes. Furthermore, we introduce interactive closed-loop patterning, enabling a dynamic feedback mechanism between the measured cell culture patterns and the light illumination profiles to achieve the desired target patterning trends. Our work offers innovative tools for advanced tissue engineering applications through seamless fusion of optogenetics, optical engineering, and cybernetics. In the field of tissue engineering, achieving precise spatiotemporal control over engineered cells is critical for sculpting functional 2D cell cultures into intricate morphological shapes. Here the authors introduce μPatternScope (μPS), a modular system for precise, automated light-based control of cell patterning in 2D cultures. [ABSTRACT FROM AUTHOR]

Terahertz (THz) absorbers, vital in advanced materials and photonics, manipulate electromagnetic waves within the 0.1 to 10 THz frequency range. These absorbers, crafted from nanostructures and metamaterials, offer applications in imaging, sensing, and communications. Diverse absorber strategies, including metamaterial-based, plasmonic, graphene-based, and photonic crystal, exploit unique physical phenomena for exceptional THz absorption. The evolution of these absorbers is propelled by advancements in fabrication techniques and computational modeling. Graphene, a two-dimensional carbon material, stands out for terahertz applications with broadband absorption, ultrafast response time, and tunability. This study presents two model graphene-based THz absorbers, designed and simulated using finite element method (FEM). The first model, in the mid-infrared range (6 to 14 μm), finds applications in thermal imaging, remote sensing, and spectroscopy. The second model, in the far-infrared range (1 to 14 THz), is versatile for spectroscopy, imaging, communication, and sensing. Key contributions include a meta-atom with the smallest footprint, a practical absorber design, and tunability through the graphene layer's chemical potential. Numerical analysis and simulations demonstrate effective absorption, and sensitivity analysis shows the impact of analyte refractive index and thickness on sensing performance. Model 2, focusing on tunable graphene absorbers, exhibits remarkable absorption characteristics, achieving tunable absorptivity from 3 to 99.5%. In conclusion, this research advances the field of tunable THz absorbers, showcasing potential in diverse applications. The proposed designs, leveraging graphene and innovative configurations, open avenues for efficient and flexible terahertz technology. [ABSTRACT FROM AUTHOR]

The photonic spin Hall effect (PSHE) at the optical interface is a polarization-dependent phenomenon of incident light. The described methodology is a novel strategy for controlling the active polarization mode of the enhanced PSHE. The PSHE is enhanced for both horizontal (H) and vertical (V) polarized light in the ∼ 1.5 mm to the submillimeter range. The enhanced PSHE has been measured for the reflected light from the modified Kretschmann configuration. An additional thin dielectric (glass) layer on the ultrathin metal (Ag, Al) layer provides simultaneous surface plasmon resonance (SPR) and wave-guiding effects. Furthermore, we demonstrated that by changing the physical parameter of the structure, we could tune the enhancement of PSHE along with the control on polarization mode. This research paves the way for new photonic devices with ultra-high sensitivity for metrological applications. Furthermore, depending on the light spin, this work enables a degree of freedom in the choosing of input light polarization for numerous potential applications. [ABSTRACT FROM AUTHOR]

This comprehensive study delves into the transformative evolution of photonic feature prediction and design, where traditional methods, deeply rooted in theory-driven computational approaches, have shaped our understanding of optical phenomena and advanced photonic structures. Integrating machine learning (ML) in photonics marks a fundamental departure from conventional predictive modeling, driven by the acknowledgment of its vast potential to deliver ingenious solutions, optimize designs, and accelerate the advancement of cutting-edge optical technologies. The article introduces a practical application of machine learning, specifically regression, to address optical engineering problems. The focal point is hexagonal photonic crystal fiber (PCF), an important photonic device with crucial input parameters such as wavelength, diameter, and pitch guiding the analysis. This hands-on application of ML showcases the adaptability of machine learning techniques. It underscores the pivotal role of creating a robust dataset as the foundational step for effective model training and application in the problem-solving of optical systems. The synergy between theory-driven computational models and data-driven machine learning approaches is explored, revealing a promising era for unlocking novel insights and driving innovation in photonics, revealing important features of photonics devices. The shift towards data-driven methodologies addresses prevailing limitations of theory-driven computational methods when navigating the intricate complexities inherent in photonic systems. Research into the dynamic interplay between established theories and emerging machine learning methodologies is poised to uncover novel insights, ultimately driving the field towards efficiently solving complex photonic systems by deploying effectively optimized neural networks to predict specific outputs for given inputs. [ABSTRACT FROM AUTHOR]

In this article, we present our analysis of the Raman-induced wavelength shift (RIWS) in configuring high-performance temperature sensor by employing a highly nonlinear Chalcogenide (As30S70) microstructured optical fiber (MOF) having central holes partially filled with Chloroform (CHCl3). Through precise adjustment of the device parameters, we demonstrate a sensitivity of temperature measurement of ~ 2.6262 nm/°C in the mid-infrared (MIR) wavelength range. Implementing Artificial Neural Network (ANN) analysis, this sensitivity increases to 2.7039 nm/°C yielding a temperature resolution of 0.24688 °C. To our knowledge, this is the first investigation that specifically addresses RIWS effect in temperature sensing using Chalcogenide fiber at MIR range. [ABSTRACT FROM AUTHOR]

A continuous Dean flow UV-C system was designed using fluorinated ethylene propylene tubing with UV-C transmission ≈60% wrapped in a serpentine path to improve axial mixing with a Dean number > 140. The microbial inactivation efficiency of the system was evaluated using Salmonella Typhimurium, E. coli O157:H7, Staphylococcus aureus, Saccharomyces Cerevisiae, and T1UV inoculated in almond milk (AM) and treated at various fluence levels at an optimized flow rate of 515 mL/min. In addition, a detailed examination of the velocity magnitude at various locations in a dean flow system, especially at the bends, was quantified. The findings indicate that a reduction > 4 log10 CFU/mL was attained for all specified microorganisms with a reduction equivalent fluence of 22.05 mJ/cm2. Additionally, computational fluid dynamics were employed to examine the velocity magnitude and incident radiation field within the tubing. In summary, the system demonstrated effectiveness in inactivating target microorganisms present in almond milk. Incorporating UV treatment in the production line allows for more environmentally sustainable practices, reducing energy consumption, and may eliminate the need for additional preservatives in plant-based beverage manufacturing. [ABSTRACT FROM AUTHOR]

Scintillation materials convert high-energy radiation to optical light through a complex multistage process. The last stage of the process is spontaneous light emission, which usually governs and limits the scintillator emission rate and light yield. For decades, scintillator research focused on developing faster-emitting materials or external photonic coatings for improving light yields. Here, we experimentally demonstrate a fundamentally different approach: enhancing the scintillation rate and yield via the Purcell effect, utilizing optical environment engineering to boost spontaneous emission. This enhancement is universally applicable to any scintillating material and dopant when the material's nanoscale geometry is engineered. We design a thin multilayer nanophotonic scintillator, demonstrating Purcell-enhanced scintillation with 50% enhancement in emission rate and 80% enhancement in light yield. The emission is robust to fabrication disorder, further highlighting its potential for x-ray applications. Our results show prospects for bridging nanophotonics and scintillator science toward reduced radiation dosage and increased resolution for high-energy particle detection. [ABSTRACT FROM AUTHOR]

Carbon fiber-reinforced polymers (CFRPs) are widely used in biomedical, optical and tissue engineering applications. Nevertheless, machining these materials significantly differs from other materials and faces special challenges. In recent years, ultrasonic drilling as a new technique was introduced in the field of composites' machining. This study evaluates the effects of nano-graphene incorporation and machining parameters including feed rate, tool type in both conventional and ultrasonic vibration assisted drilling. Besides, statistical analysis is conducted in order to identify contribution of the parameters. The results suggest that feed rate is the most influential factor on cutting force and hole quality including delamination and hole roundness. In addition, in order to acquire the best optimal process parameters, desirability method was established. That was indicated the best hole quality is achieved in CFRP samples at the least feed rate by the HSS-8% cobalt tool (M42 tool) and in presence of the ultrasonic vibration. [ABSTRACT FROM AUTHOR]

We consider interstellar power transmission facilitated by gravitational lensing. Our study explores realistic scenarios for signal transmission and relevant detection strategies. We determine that optimal link efficiency is achieved in lensing geometries where the transmitter, lens, and receiver are closely aligned. Our findings confirm the feasibility of interstellar power transmission via gravitational lensing. Additionally, we demonstrate that laser signals, amplified by nearby stellar gravitational lenses, can be detected using established photonics and optical engineering technologies. The search for these transmitted laser signals can be conducted by networks of collaborative astronomical facilities, utilizing both ground-based and space-based instruments, thereby directly contributing to ongoing optical Search for ExtraTerrestrial Intelligence (SETI) efforts. [ABSTRACT FROM AUTHOR]

The Doppler effect reveals the law that light waves undergo frequency changes in interacting with motion, which is highly significant in velocity detection and has applications in fields such as astrophysics, aerospace, and advanced manufacturing. A typical Doppler velocimetry involves illuminating a moving object with interference fringes generated based on phase gradients while detecting the frequency shift of scattered light to determine the velocity. Beyond the spatial phase distributions, the spatial amplitude is a unique dimension of light fields that can be directly controlled, but its application prospects in motion detection are rarely revealed, particularly in both the magnitude and orientation of velocity measurements. In this work, a remote vector velocimeter based on spatially structured amplitude fields is proposed for monitoring angular velocities of objects in situ. Guided through a 40 km seven‐core fiber, the structured beams with spatially‐distributed amplitude are constructed at the remote fiber facet by adjustable mode excitation in outer cores, and the Doppler signals reflected by the target are collected and transmitted back by the inner core, enabling the remote measurement of rotational motion vectors with a probe‐signal‐integrated configuration. These results suggest the great potential of spatial amplitude fields in motion detection, the cost‐efficient and compact velocimetry may contribute to the communities of optical sensing and engineering. [ABSTRACT FROM AUTHOR]

In recent years, the concept of hyperbolic phonon polaritons (HPPs) has revolutionized the field of nanophotonic, enabling unprecedented control over light-matter interactions at the nanoscale. Here, we theoretically propose and study the lateral optical forces in twisted mixed-dimensional MoO3 homostructures. Assisted with the low-symmetry HPPs, we realize a lateral optical force exerted on the Au nanoparticles near the surface of mixed-dimensional MoO3 homostructures with a linear polarized incident light. By controlling the polarization state, incident angle of light and the twisted angle of MoO3, the amplitude and direction of the lateral optical forces can be tailored in the mid-infrared range. Our findings provide a new platform for engineering lateral optical forces to manipulate diverse objects in a flexible and efficient manner. [ABSTRACT FROM AUTHOR]

Optical microscopy is widely regarded to be an indispensable tool in healthcare and manufacturing quality control processes, although its inability to resolve structures separated by a lateral distance under ~200 nm has culminated in the emergence of a new field named fluorescence nanoscopy, while this too is prone to several caveats (namely phototoxicity, interference caused by exogenous probes and cost). In this regard, we present a triplet string of concatenated O-Net ('bead') architectures (termed 'Θ-Net' in the present study) as a cost-efficient and non-invasive approach to enhancing the resolution of non-fluorescent phase-modulated optical microscopical images in silico. The quality of the afore-mentioned enhanced resolution (ER) images was compared with that obtained via other popular frameworks (such as ANNA-PALM, BSRGAN and 3D RCAN), with the Θ-Net-generated ER images depicting an increased level of detail (unlike previous DNNs). In addition, the use of cross-domain (transfer) learning to enhance the capabilities of models trained on differential interference contrast (DIC) datasets [where phasic variations are not as prominently manifested as amplitude/intensity differences in the individual pixels unlike phase-contrast microscopy (PCM)] has resulted in the Θ-Net-generated images closely approximating that of the expected (ground truth) images for both the DIC and PCM datasets. This thus demonstrates the viability of our current Θ-Net architecture in attaining highly resolved images under poor signal-to-noise ratios while eliminating the need for a priori PSF and OTF information, thereby potentially impacting several engineering fronts (particularly biomedical imaging and sensing, precision engineering and optical metrology). [ABSTRACT FROM AUTHOR]

The ARIEL mission is a European space project that aims to detect exoplanets with a spacecraft orbiting around the L2 point of the Sun-Earth system. The main payload consists of a Cassegrain telescope composed of mirrors that reflect and concentrate the incoming light from the deep space observations to finally guide it to the detectors. As in many other space missions, a dedicated complex assessment is established during the design phase to evaluate the impact on the optical performance caused by thermoelastic effects, which involves the coordinated work of the thermal, structural, and optical engineers. Despite that well-known and standardized processes and tools are established separately in each involved area, there is a lack of standardization about the way of exchanging the data between them, where additional calculations are required in some cases. This work focuses on the temperature mapping, which is the intermediate step between thermal and structural analyses, where temperatures are transferred to the structural model. The main difficulty of this process is related to the differences in modelling methods and approaches between both models, being necessary the development of an adequate algorithm to find the most accurate transfer of temperatures. This paper shows two different options for temperature mapping, detailing the proposed flowcharts. One of these methods requires the performance of an additional thermal conductive analysis, where a new improved procedure has been implemented in this work to solve some computational issues that made its application for large models difficult or even unfeasible. Both temperature mapping methods have been applied to the payload module of the ARIEL spacecraft, comparing the output results in terms of temperatures, stresses, forces, and displacements to evaluate their differences. • Structural, Thermal and Optical Performance (STOP) analysis on the ARIEL spacecraft. • Development of two procedures for temperature transfer between thermal and structural models. • Definition of a process to overcome computational issues found in thermal analysis in NASTRAN. • Validation of the proposed procedures for the temperature mapping of a large and complex model. • Comparison of results between two temperature mapping methods (PWT and PAT) on ARIEL. [ABSTRACT FROM AUTHOR]

Precisely capturing and manipulating microparticles is the key to exploring microscopic mysteries. Optical tweezers play a crucial role in facilitating these tasks. However, existing optical tweezers are limited by their dependence on specific beam modes, which restrict their ability to flexibly switch and manipulate optical traps, thereby limiting their application in complex scientific challenges. Here, we propose a new method to achieve type switching and manipulation of optical traps using a single structured beam via optical coherence engineering. A conjugate-model random structured beam with a switch is designed. By altering the state of the switch, we can change the type of optical cage, enabling the capture of different particle types. Furthermore, the range, strength, and position of the optical trap can be controlled by adjusting the initial beam parameters. We hope that optical coherence engineering will extend the capabilities of existing structured optical tweezers, paving the way for advances in future optical tweezers applications. [ABSTRACT FROM AUTHOR]

Two-dimensional WSi2X4 (X = N, P, As) has stimulated extensive studies due to its structural diversity and intriguing properties. Here, a systematic study on the strain engineering of electronic and optical properties in monolayer WSi2X4 is presented. Our results demonstrate that the monolayer WSi2X4 can withstand biaxial tensile strains of 13.1%, 16.3%, and 12.2% for X = N, P, and As, respectively, while the corresponding critical stresses are 27.90 GPa, 14.58 GPa,and 13.56 GPa, respectively. Furthermore, the bandgap of monolayer WSi2X4 can undergo a direct-to-indirect transition and even achieve a semiconductor-to-metal transition under appropriate biaxial strains. In addition, the light absorption of monolayer WSi2X4 in the visible region can be effectively improved by tensile strain, and the red (blue) shift of the absorption peak can be observed by tensile (compression) strain. The results show that monolayer WSi2X4 exhibits outstanding mechanical strength and physical properties, which is promising for future optoelectronic devices. [ABSTRACT FROM AUTHOR]

The distribution of diffuse spot energy can be used to sensitively evaluate the aberrations and defects of optical systems. Therefore, the objective and quantitative measurement of diffuse spot parameters is an important means to control the detection quality of space debris detection systems. At present, the existing optical system dispersion measurement method can only judge whether the energy distribution meets the index. However, these methods ca not provide an objective quantitative basis to guide the installation process. To solve this problem, a mathematical simulation model of 3D multi-phase sub-pixel PSF distribution is proposed. According to the relation between the CCD target plane and the theoretical image plane (focal plane, defocus, and deflection), the diffuse spot distribution of the optical system is simulated with different phase combinations. Then, Pearson Correlation Coefficient (PCC) is used to evaluate the matching similarity of the diffuse spot image. The simulation results show that when the PCC is greater than 0.96, the distribution of the two diffuse spots can be identified as matching. This also confirms the accuracy of the proposed PSF model. Then, the focusing deviation of the system being tested can be analyzed according to the phase size of the diffuse spot simulation image. This method can quickly and accurately guide the focal surface installation and testing of the system. Therefore, the purpose of improving the detection accuracy of space debris is achieved. It also provides a quantitative basis for the engineering application of optical detection systems in the future. [ABSTRACT FROM AUTHOR]

Metamaterial has been captivated a popular notion, offering photonic functionalities beyond the capabilities of natural materials. Its desirable functionality primarily relies on well-controlled conditions such as structural resonance, dispersion, geometry, filling fraction, external actuation, etc. However, its fundamental building blocks--meta-atoms--still rely on naturally occurring substances. Here, we propose and validate the concept of gradient and reversible atomic-engineered metamaterials (GRAM), which represents a platform for continuously tunable solid metaphotonics by atomic manipulation. GRAM consists of an atomic heterogenous interface of amorphous host and noble metals at the bottom, and the top interface was designed to facilitate the reversible movement of foreign atoms. Continuous and reversible changes in GRAM's refractive index and atomic structures are observed in the presence of a thermal field. We achieve multiple optical states of GRAM at varying temperature and time and demonstrate GRAM-based tunable nanophotonic devices in the visible spectrum. Further, high-efficiency and programmable laser raster-scanning patterns can be locally controlled by adjusting power and speed, without any mask-assisted or complex nanofabrication. Our approach casts a distinct, multilevel, and reversible postfabrication recipe to modify a solid material's properties at the atomic scale, opening avenues for optical materials engineering, information storage, display, and encryption, as well as advanced thermal optics and photonics. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is a pathogen that infects wounds and burns and causes severe infections in immunocompromised humans. The high virulence, the rise of antibiotic‐resistant strains, and the easy transmissibility of P. aeruginosa necessitate its fast detection and control. The gold standard for detecting P. aeruginosa, the plate culture method, though reliable, takes several days to complete. Therefore, developing accurate, rapid, and easy‐to‐use diagnostic tools for P. aeruginosa is highly desirable. Nanomaterial‐based biosensors are at the forefront of detecting P. aeruginosa and its secondary metabolites. This review summarises the biorecognition elements, biomarkers, immobilisation strategies, and current state‐of‐the‐art biosensors for P. aeruginosa. The review highlights the underlying principles of bioreceptor layer engineering and the design of optical, electrochemical, mass‐based, and thermal biosensors based on nanomaterials. The advantages and disadvantages of these biosensors and their future point‐of‐care applications are also discussed. This review outlines significant advancements in biosensors and sensors for detecting P. aeruginosa and its metabolites. Research efforts have identified biorecognition elements specific and selective towards P. aeruginosa. The stability, ease of preparation, cost‐effectiveness, and integration of these biorecognition elements onto transducers are pivotal for their application in biosensors and sensors. At the same time, when developing sensors for clinically significant analytes such as P. aeruginosa, virulence factors need to be addressed, such as the sensor's sensitivity, reliability, and response time in samples obtained from patients. The point‐of‐care applicability of the developed sensor may be an added advantage since it enables onsite determination. In this context, optical methods developed for P. aeruginosa offer promising potential. [ABSTRACT FROM AUTHOR]

Indoor organic photovoltaics (IOPVs) with tunable absorption spectra and relatively high power conversion efficiency (PCE) have emerged as one of the most promising energy sources for Internet of Things devices, but enhancing the device performance under various directions of indoor illumination is challenging. Herein, it is proposed to combine omnidirectional optical engineering and ternary strategy for achieving high‐performance IOPVs. The advantage is taken of a ternary bulk heterojunction (BHJ) with a polymer donor having aligned absorption spectra with the light‐emitting diode (LED) spectrum and a guest component that not only blueshifts the near‐infrared absorption of the acceptor but also improves electrical and morphological properties of the BHJ. A 2D photonic‐structured antireflection coating is further developed to selectively improve the light absorption of IOPVs, leading to a PCE of 29.07% under 1000 lux LED illumination. More importantly, the antireflection coating maintains the initial PCE even when irradiated by light incident at large angles, demonstrating an omnidirectional effectiveness. This weaker angular dependency on light absorption provides practical prospects for future sustainable indoor photovoltaic systems. [ABSTRACT FROM AUTHOR]

Optical skyrmions are topologically stable quasiparticles that can be constructed with electric field, spin angular momentum, polarization Stokes vector, pseudospin, etc. In this letter, both theoretical and experimental studies are carried out to reveal the role of Gouy phase in the topology transformation during the tight focusing of Stokes skyrmions. The Stokes skyrmionic beam can be constructed by superposing two orthogonally polarized components with orthogonal spatial modes. The Gouy phase produced in the focused field depends on the orbital angular momentum carried by the high order mode component of the incident Stokes skyrmionic beam. While the beam size of the focused field is diffraction limited, the variation of the Stokes vectors in the skyrmion topology is in the sub‐diffraction limited scale. The presented results shed light on the understanding of the topology transformation between the incident and the tightly focused fields, paving the way for engineering the optical skyrmions in micro‐nano scale and their applications in information processing, quantum technology, metrology, etc. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) transition metal dichalcogenides (TMDs) have garnered considerable attention for their promising applications in sensors and optoelectronic devices, owing to their exceptional optical, electronic, and optoelectronic properties. However, the inherent high symmetry of TMD lattices imposes limitations on their functional versatility. Here, we present a strategy to disrupt the C3 rotational symmetry of monolayer WSe2 by fabricating a heterostructure incorporating WSe2 and SiP flakes. Through comprehensive experimental investigations and first-principle calculations, we elucidate that in the WSe2/SiP heterostructure, excitons—both neutral and charged—emanating from WSe2 exhibit pronounced anisotropy, which remains robust against temperature variations. Notably, we observe an anisotropic ratio reaching up to 1.5, indicating a substantial degree of anisotropy. Furthermore, we demonstrate the tunability of exciton anisotropy through the application of a magnetic field, resulting in a significant reduction in the anisotropic ratio with increasing field strength, from 1.57 to 1.18. Remarkably, the change in heterojunction anisotropy ratio reaches 24.8% as the magnetic field increases. Our findings elucidate that the perturbation of the C3 rotational symmetry of the WSe2 monolayer arises from a non-uniform charge density distribution within the layer, exhibiting mirror symmetry. These results underscore the potential of heterostructure engineering in tailoring the properties of isotropic materials and provide a promising avenue for advancing the application of anisotropic devices across various fields. [ABSTRACT FROM AUTHOR]

Optogenetics opened the door to a new era of neuroscience. New optical developments are under way to enable high-resolution neuronal activity imaging and selective photostimulation of neuronal ensembles in freely moving animals. These advancements could allow researchers to interrogate, with cellular precision, functionally relevant neuronal circuits in the framework of naturalistic brain activity. We provide an overview of the current state-of-the-art of imaging and photostimulation in freely moving rodents and present a road map for future optical and engineering developments toward miniaturized microscopes that could reach beyond the currently existing systems. [ABSTRACT FROM AUTHOR]

Photonic technologies have made enormous impacts on modern medicine, advancing disease diagnostics and treatments as well as health monitoring. A long‐standing challenge in the use of light and its widespread effects in photomedicine is the finite penetration of light in tissues. However, judiciously engineered optical fibers helped overcome this challenge and advance light delivery to deep tissues with spatial precision and desired accessibility. In recent years, the development of photonic technologies including optical biomaterials, fiber functionalization, and biomedical device innovations has greatly expanded the scope of light‐based healthcare. Here, the fundamentals and materials of fiber optics to endow themselves with biocompatibility, flexibility, and diverse functionalities required for long‐term implantation are overviewed. The design strategies of lab‐on‐fiber techniques, operation requirements to construct fiber optic sensors, and their health monitoring applications as wearable and implantable devices are presented. The use of fiber optics in major light‐based therapeutic modalities including optogenetics, photodynamic therapy, photobiomodulation, photochemical cross–linking, and photothermal therapy is illustrated to enhance their effectiveness, specificity, and feasibility. In short, a comprehensive review is provided on the fiber optic techniques and the latest photonic devices, which are envisioned to evolve photomedicine in clinical and point‐of‐care practices. [ABSTRACT FROM AUTHOR]

Coherent Rayleigh scattering‐based distributed fibre optic sensing technology enables real‐time acquisition of vibration and acoustic information along the optical fibres. However, the complexity of monitoring environments often leads to false alarms and missed detections during the process of information source identification with distributed acoustic sensing (DAS). Therefore, it becomes crucial to effectively extract meaningful signal features and perform accurate pattern recognition in the presence of external noise disturbance. The authors provide a comprehensive review of signal feature extraction and pattern recognition techniques applied in DAS technology. After introducing the fundamentals of DAS, specific applications are considered, and the following techniques have been analysed and compared: feature extraction algorithms based on wavelet decomposition, feature extraction schemes utilising other decomposition models, traditional recognition classifiers, and neural network‐based recognition classifiers using deep learning. The advantages and limitations of each scheme are discussed, along with their potential applications in various scenarios. The aim is to provide insights into the latest technologies in signal processing and pattern recognition for DAS, fostering further advancements in this field. [ABSTRACT FROM AUTHOR]

Herein, we report the metal ion sensing property of two 2,2'‐bis (pyridylmethyl) amine‐based chromogenic probes at physiological pH in buffered media. The binding of metal ions to the bispicolyl site alters its electronic property, which subsequently influences the optical property of the covalently‐linked signaling unit. The compound experienced a change in the solution color from red to deep and light yellow respectively upon the addition of Cu2+ and Ni2+ ions. Further, it is observed that by modifying the signaling unit, one can tune the mode of metal ion binding and sensitivity. The compound with an electron‐deficient quinolinium unit as the signaling moiety, showed 2 : 1 stoichiometry of binding with metal ions, while the compound functionalized with a pyrene unit formed complexes with 1 : 1 stoichiometry. It was conferred that changes in the signaling moiety not only alter the basicity/nucleophilicity of the pyridine nitrogen ends but also influence their aggregation properties. Such kind of studies will be beneficial for engineering new optical probes with tuneable sensitivity. [ABSTRACT FROM AUTHOR]

In this study, we examine the dynamic behavior of optical solitons in the nonlinear conformable Gross–Pitaevskii equation (GPE) within Bose–Einstein condensates, which refer to the phenomenon of many ultra-cold bosonic particles occupying a single quantum state. The GPE is a cornerstone of advanced statistical physics, has application in various engineering disciplines, particularly in the realm of quantum mechanics and optical engineering. By precisely encoding the GPE’s steady-state solutions, we make it possible to compute nonlinear models pertinent to engineering systems and clarify solutions within particular parameter regimes that are essential for engineering applications. Our study encompasses repulsive and attractive nonlinearities in GPE, including quadratic and double-well potentials. We focus on discovering solutions, employing the generalized Riccati equation mapping method and modified extended tanh-function method to extract soliton solutions. The study yields a variety of soliton including combined dark–bright, singular, combo dark-singular, periodic-singular, and rational solutions with physical perspectives. Through 2D and 3D representations, the internal structure of these phenomena is effectively illustrated, offering insights into their behavior and dynamics, which is significant for optimization process and engineering design. [ABSTRACT FROM AUTHOR]

Doped semiconductors are more advantageous than pure semiconductors, because doping of a semiconductor can tune electrical conductivity and optical bandgap engineering that allows flexible designs of microelectronic and optoelectronic devices, respectively. In the present work, pure and Mn-doped SnO2 nanocrystallites have been prepared using single-step wet chemical method calcined at 500 °C and 650 °C to investigate structural, optical, impedance, and ferromagnetic properties. X-ray diffraction confirmed single-phase Mn-doped SnO2, and NEXAFS spectra further revealed + 2 oxidation state of Mn ions in SnO2. The surface morphology depicted densely packed grains and optical spectra showed Mn and temperature-dependent variation of bandgaps. While dielectric and impedance study disclosed frequency response and dominance of grains resistance. Further, conduction mechanism and room temperature ferromagnetism were improved with doping and sintering temperature. Hence, prepared compounds are attractive for frequency-related devices and data storage applications. [ABSTRACT FROM AUTHOR]

Endoscopy, enabling high-resolution imaging of deep tissues and internal organs, plays an important role in basic research and clinical practice. Recent advances in photoacoustic microscopy (PAM), demonstrating excellent capabilities in high-resolution functional imaging, have sparked significant interest in its integration into the field of endoscopy. However, there are challenges in achieving functional PAM in the endoscopic setting. This Perspective article discusses current progress in the development of endoscopic PAM and the challenges related to functional measurements. Then, it points out potential directions to advance endoscopic PAM for functional imaging by leveraging fiber optics, microfabrication, optical engineering, and computational approaches. Finally, it highlights emerging opportunities for functional endoscopic PAM in basic and translational biomedicine. [ABSTRACT FROM AUTHOR]

In this research work, the nonlinear Landau–Ginzburg–Higgs model under investigation on the base of auxiliary equation method. The nonlinear Landau–Ginzburg–Higgs equation mainly describe nonlinear wave propagation, categorizes wave velocity, and materializes several phenomena through the dispersive system. The secured optical soliton solutions are interested, more general and some novel in kink solitons, bright solitons, periodic singular solitons, anti-kink solitons and dark solitons. The physical structure of some explored solitons solutions are represented graphically as contour, 2D and 3D plots by utilizing the symbolic computational tool Mathematica. The secured soliton will be play important role to the investigation of nonlinear phenomena in the various domains of nonlinear sciences and engineering such as optical fibers, nonlinear dynamics, communication system, solitons wave theory, nonlinear optics, transmission system, electronic engineering and ocean engineering. The auxiliary equation method is a basic analytical, powerful, efficient approach for the investigation of optical soliton inside the nonlinear Landau–Ginzburg–Higgs equation and also other nonlinear equations. [ABSTRACT FROM AUTHOR]

The article discusses the development and dissemination of open-source neurophotonic tools for neuroscience research. It highlights the importance of accessibility for technology adoption in neurobiology and showcases examples of successful open-source tools like the UCLA Miniscope Project. The document also includes papers on widefield imaging systems, software packages for dendritic analysis, advancements in miniaturized neurophotonic interfaces, and evaluation methods for neuroscience imaging tools. Overall, the article emphasizes the impact of open-source development on advancing neuroscience research and encourages collaboration among scientists from diverse fields for innovative discoveries. [Extracted from the article]

The construction of active materials with controllable optical response facilitates the development of advanced photonic devices. However, the achievement of robust active materials with wide wavelength tunable and broadband emission remains a great challenge, mainly due to the fixed energy levels of conventional active dopants and limited inhomogeneous broadening in common hosts. Here, the study proposes that the cluster in the mesoscopic scale of ≈1 nm may break this bottleneck issue and demonstrate a strategy for the management of photon emission by engineering the cluster evolution. The amorphous glass as the host to tailor the characteristic configuration of Te clusters from 1 to 2 nm by control of the topological structures in glass is employed. Impressively, it presents a distinct optical response totally different from the conventional active centers and this enables to construct of active photonic glass with continuously tunable emission from 888 to 1064 nm. More importantly, Te cluster‐activated photonic glass fibers are fabricated and the broadband on‐off gain is successfully achieved. Furthermore, benefiting from the unique tunable emission, novel near‐infrared devices are constructed and their application in imaging is demonstrated. The approach of cluster engineering mediated tunable optical response is believed to bring new opportunities for developing advanced photonic devices. [ABSTRACT FROM AUTHOR]

High-throughput microscopy is vital for screening applications, where three-dimensional (3D) cellular models play a key role. However, due to defocus susceptibility, current 3D high-throughput microscopes require axial scanning, which lowers throughput and increases photobleaching and photodamage. Point spread function (PSF) engineering is an optical method that enables various 3D imaging capabilities, yet it has not been implemented in high-throughput microscopy due to the cumbersome optical extension it typically requires. Here we demonstrate compact PSF engineering in the objective lens, which allows us to enhance the imaging depth of field and, combined with deep learning, recover 3D information using single snapshots. Beyond the applications shown here, this work showcases the usefulness of high-throughput microscopy in obtaining training data for deep learning-based algorithms, applicable to a variety of microscopy modalities. Implementing point spread function (PSF) engineering in high-throughput microscopy has proved challenging. Here, the authors propose a compact PSF engineering approach, which allows for enhanced depth of field and for the recovery of 3D information using single snapshots. [ABSTRACT FROM AUTHOR]

Nonlinear partial integro-differential equations (PIDEs) are applied to present the various practical phenomena in a multitude of sectors of modern science and engineering, especially in optic fiber, quantum electronics, modern physics, and the special field of nonlinear wave motion. Basically, our research demonstrates a way to generate a significant quantity of solutions to these types of two PIDEs. In this research, we have used an efficient mathematical tool namely the generalized G ′ / G -expansion method to acquire the closed form soliton solutions for the (2 + 1)-dimensional first integro-differential Kadomtsev–Petviashivili (KP) hierarchy equation and the (2 + 1)-dimensional second integro-differential KP hierarchy equation utilizing a code likely Mathematica. The explicit closed form soliton solutions of these two PIDEs are found in the pattern of trigonometric, hyperbolic, and rational functions which are compared to all the well-known results that are yielded in the paper. We attain solutions that are graphically displayed in addition to physically described in 3D structure, contour, and 2D, such as a bell-shaped soliton, a singular bell-shaped soliton, and some kink-shaped solitons. As far as the authors' wisdom, the outcomes of these problems gained by the offered expansion method are renewed closed form solitary wave and investigated here for the first time. The analysis of obtained results will be able to provide a constructive explanation of the physical phenomena in optical physics and engineering. [ABSTRACT FROM AUTHOR]

The realization of Janus monolayers presents an exciting opportunity to disrupt structural symmetry, opening up novel avenues in the realm of layered materials. While several ternary systems, comprising the group-III monochalcogenides, has been proposed for this purpose, the impact of oxygen interaction on the electronic, thermoelectric and optical characteristics of gallium and indium monochalcogenides has been observed. Interestingly, the concept of incorporating oxygen as a third element in ternary systems has not yet been explored extensively. Here we embark on the design and exploration of 2D A2OX (A = Ga, In and X = S, Se) monolayer through first-principles calculations. Our investigation includes the analysis of electronic band structure, optical and thermoelectric properties, revealing that Ga2OS, Ga2OSe and In2OS exhibit direct band nature. However, In2OSe is found to be metallic in unstrained condition. Moreover, the band gap in these materials can be fine-tuned through the application of tensile or compressive strain. Additionally, our analysis suggests strong optical absorption within the visible, and/or ultraviolet regions, depending on the specific system under consideration. Our findings reveal that Ga2OS and In2OS monolayers elevated power factors with application of tensile strain, rendering them as compelling candidates for applications in thermoelectric devices. [ABSTRACT FROM AUTHOR]

Defects introduced to synthetic type Ib diamond micrometer-size particles by electron-beam irradiation were studied by electron paramagnetic resonance and photoluminescence (PL) spectroscopy as a function of e-beam fluence and post-irradiation thermal annealing. Increasing electron-beam fluence causes a substantial reduction of the substitutional nitrogen (P1) content, accompanied by progressively higher concentrations of paramagnetic negatively charged vacancies (V−) and triplet interstitials (R1/R2). Annealing results in a drastic decrease in the V− and R1/R2 content and an increase in the negatively charged nitrogen-vacancies (NV− or W15). Analysis of PL spectra allows for identification of color centers in the irradiated diamond samples and following their evolution after annealing. These data facilitate understanding of different factors contributing to the formation of color centers in diamond and promote efforts toward controlled engineering of optical centers in fluorescent diamond particles. [ABSTRACT FROM AUTHOR]