Search

Plasmonic tilted fiber Bragg gratings (TFBGs) have emerged as versatile tools for refractometric analyses and biochemical sensing. Their applications have significantly blossomed these last years, from proteins and cellular bioassays to operando monitoring in batteries, to cite just a few. They are widely recognized for their cutting‐edge performance and low limits of detection, arising from their dense multimodal spectral nature featuring tens of narrowband cladding mode resonances. Their comb‐like spectrum is so rich that numerous demodulation techniques have been reported, without benchmark of their relative performance while they possess important distinctions. This review highlights developments in detangling techniques from the pioneering works based on single‐peak analysis up to the most recent approaches involving Fourier analysis, the implementation of machine learning, and cascaded spectral decomposition processes. To fairly compare the different techniques of the literature, we implemented each analysis on original experimental refractometric calibrations, revealing the assets of the most updated methods. This paper therefore reviews these demodulation techniques based on the same datasets, obtained under the same conditions. We show and discuss the results obtained from bioassays and pinpoint the importance of advanced analytical methodologies to maximize the reproducibility, reliability and performance of plasmonic‐based TFBGs biosensors. [ABSTRACT FROM AUTHOR]

In head and neck squamous cell carcinoma (HNSCC), early complications of the radiotherapy (RT) are observed from the beginning of the treatment to a few months after its end. During external radiotherapy treatment, several patient-dependent parameters can cause a modification of the dose distribution compared to the planned distribution due to variation in patient positioning, anatomy, or intra-fractional movements for example. To verify these parameters during treatment sessions, one of the most commonly used solutions is the cone-beam computed tomography (CBCT). Nowadays, the use of CBCT may constitutes a significant part of the total dose at the end of treatment (up to 10 cGy per session) and more often the volume irradiated by imaging is larger than the one irradiated by the treatment, leading to unintentional irradiation of nearby organs. In this study, we asked whether the imaging low dose added to a following fraction dose (2 Gy) may affect the biological response in terms of DNA repair. Using an IVInomad dosimeter and scintillating fiber probes specially designed for this exploratory study, we exposed fibroblasts cells from head and neck cancer (HNC) patients to a CBCT dose followed by a radiotherapy fraction dose. DNA double strand breaks and DNA repair were assessed by immunofluorescence using the biomarkers gamma H2AX (γH2AX) and pATM. The median dose of CBCT was measured between 17 to 21 mGy per session. The kinetics of both biomarkers were found to be strongly dependent on the individual factor in radiosensitive patients. For HNC patients, a prior CBCT dose applied few minutes before the 2 Gy dose may have a sublinear effect on the DNA repair mechanisms and potentially on observed health tissue toxicity. The preliminary results obtained highlight the importance of individual and tissue factors for recognizing and repairing DSB during a treatment by radiotherapy using CBCT. [ABSTRACT FROM AUTHOR]

Optical fibers are used in the communications, biological sensors and chemical sensors. We investigate a variable-coefficient modified Hirota equation for the amplification or absorption of pulses propagating in an inhomogeneous optical fiber. With respect to the complex envelope of the optical field, we construct the infinitely-many conservation laws based on the existing Lax pair. According to the existing Darboux transformation, we derive the three-soliton solutions, the higher-order breather solutions and breather-to-soliton transition condition. Amplitudes of the two solitons change after the interaction, while velocities of them are unchanged via asymptotic analysis. When $ P(z)=0 $ P (z) = 0 , interactions among the three parabolic or wavy solitons, interaction between the two parabolic or wavy or crooked breathers, and interactions among the three parabolic and wavy breathers are presented, where $ P(z) $ P (z) is related to the nonlinear focus length. Velocities of three solitons or two crooked breathers with $ P(z)\neq 0 $ P (z) ≠ 0 are different from those with $ P(z)=0 $ P (z) = 0. Based on the breather-to-soliton transition condition, when $ P(z)=0 $ P (z) = 0 , parabolic or wavy multi-peak and M-shaped solitons are presented; when $ P(z)\neq 0 $ P (z) ≠ 0 , the crooked periodic wave and anti-dark soliton are shown. [ABSTRACT FROM AUTHOR]

Fiber combiner is an effective device to enhance the power level or broaden the spectral wavelengths through a single monolithic output aperture, by fusing multiple fibers together. This is particularly important in mid‐infrared (MIR) 2–5 µm range, in which the output power of a single laser is limited. Due to the high MIR transmission, chalcogenide glass is an ideal host for constructing MIR fiber combiner. In this study, we report the design, fabrication, and characterization of a homemade 3 × 1 chalcogenide glass fiber combiner. The fiber combiner includes a 3 × 1 As–S input fiber bundle and an output fiber. The input fiber bundle was made by tapering three As–S multimode fibers with a core diameter of 200 µm and a cladding diameter of 250 µm. The taper reduction ratio R was 2, and the length of the taper transition region was ∼2 cm. The output fiber with core diameter of 360 µm and cladding diameter of 570 µm was then spliced with the tapered end of the fiber bundle. The total length of the combiner was ∼53 cm. The measurement of power combination at 4.56 µm indicated that the transmission efficiency of three ports reached 80%, whereas the power combining efficiency of the combiner was measured to be ∼48%. In addition, efficient wavelength combining over one octave has been demonstrated, by launching three different lasers at 2.1, 3.39, and 4.56 µm through the 3 × 1 combiner. It proves that chalcogenide fiber combiner is promising for the applications of high‐level power combination and broadband wavelength combining in MIR 2–5 µm range. [ABSTRACT FROM AUTHOR]

In this article, we discuss the scientific research we conducted to ensure information security on concrete structures using the fiber Bragg grating method. As a result, guided by the experiences of other researchers and their results in our studies, the main hazards were identified, and the influence of temperature and deformation sensors in concrete was studied. The work determines the dependence of temperature on the optical cable and its effect on concrete deformation. It also studies the change in the internal structure of the optical fiber when exposed to concrete, and in comparison, with non-concrete optical fiber. In the experimental chapter, conducted on laboratory bench, we consider and study the signal transmission structure of an optical sensor that experiences deformation upon impact with concrete and such fibers. Graphic data was obtained using the OptiSystem program. During the process of determining the optical power of the sensors, we discovered that the higher the vibration during signal transmission, the higher the power of the optical data acquisition system unit. The results presented in this paper show the promise of fiber optics in other environments, as well as new discoveries in the construction industry and the successful use of electrical laser sensors to maintain temperature and stress in a variety of concrete structures, including cooling towers in nuclear and thermal power plants. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) broadband active photonic materials play a crucial role in various domains such as optical communication, phototherapy, and medical imaging. However, the construction of NIR photonic materials with tunable optical response still remains a great challenge. This manuscript proposes a topological structure engineering strategy in Bi‐activated glass for the realization of the controllable NIR emission. By manipulating the topological structure of glass, the Bi cluster configuration can be precisely control, with the cluster size from 2.78 to 1.64 nm. Correspondingly, various optical properties including broadband emission, excited state absorption (ESA), and even unsaturable loss (UL) can be rationally switched. Based on the above findings, Bi cluster‐activated bulk glasses, optical fibers, and the derived NIR active devices with notably improved performance can be successfully fabricated. Their application potentials in optical communication and NIR imaging are also demonstrated. The study highlights the promise of Bi cluster‐activated materials in advancing NIR photonic materials and devices. Furthermore, the topological‐mediated cluster regulation strategy may also provide new insights into the fundamental science and cutting technology of other cluster‐activated materials. [ABSTRACT FROM AUTHOR]

Recent studies investigated the hydrolysis of Magnesium (Mg) thin films, highlighting their potential use in biodegradable devices. Quantitatively monitoring the degradation rate and morphological changes of Mg through optical methods and light‐delivery devices offers an innovative, contactless technique, independent of electrical wiring. This method is particularly useful for challenging sensing applications. This study introduces a set of strategies based on Mg optrodes where hydrolysis drives the real‐time monitoring of biofluid penetration through thin‐film encapsulations for bioelectronics. This enables a straightforward assessment of their long‐term reliability, through a quantitative correlation between the water transmission rate (WTR) of the encapsulation and the Mg optical modifications. The optical response of the corroding Mg films deposited on glass substrates and multimode optical fibers tips, within the visible spectrum is characterized. Finally, it is demonstrated that nanopatterning of Mg films as plasmonic nanoantennas significantly enhances the sensitivity of the quantitative approach in the mid‐Infrared spectrum through localized plasmon effects. This method achieves a WTR detection of 6.9 × 10−3 gm−2 day−1 in phosphate buffer solution (25 °C), with a theoretical lower detection limit of ≈10−5 gm−2 day−1. These findings pave the way for the development of a new class of nano‐optical water‐permeation sensors. [ABSTRACT FROM AUTHOR]

The integration of plasmonic nanostructures in an optrode sensing system holds significant promise for online and remote detection via surface-enhanced Raman scattering (SERS) method. This study focuses on the impact of the shape and composition of plasmonic materials on their ability to enhance surface-enhanced Raman scattering (SERS) signals. We compared the SERS performance of optical fiber (OF)-based sensors (OFSs) with flattened end faces, which were decorated with six mono- and bimetallic nanomaterials: Au nanoparticles (NPs), Ag NPs, Ag-coated Au NPs (Au@Ag CSNPs), Au nanostars (NSs), Ag NSs, and Ag-coated Au NSs (Au@Ag CSNSs). Among these nanomaterials, polyhedral Au@Ag CSNSs demonstrated superior SERS enhancement, mainly attributed to multifaceted hotspots on their surface and the plasmonic coupling between the Au core and Ag shell. This allowed for precise customization of the surface plasmon resonance (SPR) and distinct enhancement of the SERS efficiency by modulating the thickness of Ag shell. Our sensing system exhibited great potential, achieving the lowest detection limit of ∼5 × 10–8 M for crystal violet, which surpasses the performance of previous OF-based sensors with the same type of flattened facets. [ABSTRACT FROM AUTHOR]

AbstractThis article aims to showcase recent advances on Optical Fiber distributed strain measurement systems applied to concrete monitoring. It focuses on their ability to accurately quantify concrete strain in post-tensioned containment buildings of nuclear power plants under various conditions, including instantaneous concrete strain due to pressure tests, delayed concrete strain due to creep/shrinkage, and instantaneous concrete strain due to tendon rupture. To achieve this, the study considers several mockups including the VeRCoRs building, a 1/3 scale post-tensioned concrete containment mockup equipped with a large number of monitoring systems. This mockup facilitates the testing and qualification of distributed measurement systems within concrete structures during both operational phases (for prestressing monitoring) and pressure tests (for measuring instantaneous strain/displacement under pressure). Additionally, a post-tensioned beam was specifically designed and fabricated to examine tendon re-anchorage after cutting. Another objective is to assess various Optical Fiber Cables (OFC) from different suppliers to ensure reliable measurements. The study also aims to test different installation methods, such as embedding the OFC into concrete or attaching them to the external surface using various adhesives. [ABSTRACT FROM AUTHOR]

Gain medium‐doped active optical fibers for optical amplification and long‐range transmission have triggered a lot of researches. Traditional rare‐earth ion‐doped active fibers have non‐adjustable emissions, narrow band luminescence, limited gain enhancement, and other challenges. The unique optical properties of quantum dots (QDs) can further improve the doped optical fibers in the light amplification capacity, temperature sensitivity and to gain a broad‐spectrum coverage and lower laser threshold and other superiorities. However, there are few systematic discussions on the development of the technologies and applications of those QD‐doped optical fibers. In this review, the optical properties, temperature characteristics and optical amplification mechanisms of QD‐doped optical fibers are outlined. Then, the preparation technologies and the applications of QD‐doped optical fibers are highlighted. Additionally, the existing challenges and future development prospects of QD‐doped optical fibers are discussed. [ABSTRACT FROM AUTHOR]

Recently, dense wavelength division multiplexing passive optical networks (DWDM-PONs) have become a considerable choice for 5G and beyond fronthaul implementations. Formerly, we have proposed a full-duplex bidirectional DWDM-PON architecture convenient for those implementations and analyzed the combined dual impact of four-wave mixing (FWM) and stimulated Raman scattering (SRS) nonlinear impairments on the proposed architecture. Meanwhile, a detailed literature analysis showed us that the combined quadruple impact of self phase modulation (SPM), cross phase modulation (XPM), FWM and SRS on the performance of bidirectional DWDM-PONs have never been researched up to now. In this paper, quadruple impact of SPM, XPM, FWM and SRS on the performance of both uplink channels (ULCs) and downlink channels (DLCs) of the formerly proposed DWDM-PON has been analyzed with simulations. Simulations have been performed in O-band region for ULCs and in C-band region for DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs having 12.5 GHz, 25 GHz, 50 GHz, 100 GHz equally-spaced channels. The quadruple impact of optical nonlinear impairments on the DWDM-PON performance has been analyzed with signal-to-crosstalk ratio (SXR) simulations performed under varying channel input powers and channel lengths. Results show that under the quadruple nonlinear impact reliable bidirectional transmission with an SXR over 23 dB can be achieved for channel input powers below 0.58 mW and 0.16 mW in 2 × 15- and 2 × 63-channel DWDM-PONs, respectively, for all channel spacing values and 25 km transmission lengths. Moreover, results also imply that variations in channel lengths do not significantly affect SXR at both ULCs and DLCs of 2 × 15- and 2 × 63-channel DWDM-PONs for lengths exceeding 50 km. The thorough analysis presented in the paper will give a new insight for analysis of conventional and next generation PONs. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance‐based fiber optic sensors with Ag‐SnO2 and Ag‐ZnS bi‐layers are proposed experimentally and compared in detail in terms of sensitivity. Effect of SnO2 and ZnS layer thicknesses on the sensitivity is examined. Largest sensitivities are achieved by sensors with 40 nm Ag‐10 nm SnO2 layers and 40 nm Ag‐10 nm ZnS layers. Sensor with 40 nm Ag‐10 nm SnO2 layers is found to demonstrate better sensitivity than that with 40 nm Ag‐10 nm ZnS layers. [ABSTRACT FROM AUTHOR]

The article presents the work on the effect of temperature on time transfer through optical fiber link and the comparison between two different lengths, i.e., 300 m and 30 km of fibers. We observed more than 200 ps offset arising during 68 days of measurement. [ABSTRACT FROM AUTHOR]

An optical fiber scale sensor based on the detection principle of surface plasmon resonance (SPR) was developed for the rapid, high-sensitivity, real-time evaluation of scale precipitation in geothermal fluids. The optical fiber SPR scale sensor was fabricated by depositing a gold thin film onto the surface of an optical fiber with an exposed core. The optimal gold film thickness of the sensor was determined to be 30 nm, which achieved a refractive index sensitivity of 2140 nm per refractive index unit. A field test was conducted using geothermal brine from the Obama Binary Geothermal Power Plant in Unzen, Nagasaki Prefecture. A conventional optical fiber scale sensor and the SPR sensor were simultaneously assessed using raw and pH-adjusted brines. For the SPR sensor, a peak shift of 0.27 nm/min was observed at a response time of 1 min, whereas no change in transmittance was observed for the conventional sensor until 180 min. After the experiments, a scanning electron microscopy-energy-dispersive spectroscopy analysis was conducted on the sensors, and the findings showed that the deposition of Mg-SiO2 scale did not significantly differ between the two sensors. The developed SPR sensor achieved faster scale precipitation detection (tens of minutes to hours) than the conventional sensor. [ABSTRACT FROM AUTHOR]

The formation of scale in hot springs and geothermal brines can be detected quickly and easily using optical fiber-based scale sensors. This paper describes the development of a portable sensor for the in situ detection of scale in geothermal water. This sensor was used to detect the formation of calcium carbonate and silica scale and to assess the effectiveness of their inhibitors. The performance of the sensor was evaluated using calcium carbonate scale. In laboratory experiments using both the newly developed sensor and a conventional nonportable sensor, the strength of the transmitted signal was found to decrease significantly as the amount of scale increased. It was considered that this sensor can accurately evaluate only scale formation without being affected by turbidity. The scale that was deposited on each material (optical fiber core, glass plate, polyvinyl chloride (PVC), and SUS304) was observed using a shape analysis laser microscope. Based on these observations, we concluded that this sensor could be used to predict the amount of scale deposited in real time. In situ evaluation of the sensor was conducted at a blowout carbonated hot spring on Rishiri Island, which is located off the coast of Hokkaido, Japan. The results obtained from experiments using hot spring water showed a similar sensor response within a comparable time range as those obtained from the laboratory experiments. The results of this study thus demonstrate that this novel portable scale sensor is suitable for use in geothermal power plants and investigating effectiveness of inhibiters under different conditions. [ABSTRACT FROM AUTHOR]

This preclinical study was conducted to investigate the efficacy of interstitial PDT (i-PDT) for malignant gliomas arising deep within the brain, which are difficult to remove. C6 glioma cells were implanted into the basal ganglia of rats, and 3 weeks later, the second-generation photosensitizer talaporfin sodium (TPS) was administered intraperitoneally. Ninety minutes after administration, a prototype fine plastic optical fiber was punctured into the tumor tissue, and semiconductor laser light was irradiated into the tumor from a 2-mm cylindrical light-emitting source under various conditions. The brain was removed 24 h after the i-PDT and analyzed pathologically. The optical fiber was able to puncture the tumor center in all cases, enabling i-PDT to be performed. Histological analysis showed that tumor necrosis was induced in areas close to the light source, correlating with the irradiation energy dose, whereas apoptosis was induced at some distance from the light source. Irradiation using high energy levels resulted in tissue swelling from strong tumor necrosis, and irradiation at 75 J/cm2 was most suitable for inducing apoptosis. An experimental system of i-PDT using TPS was established using malignant glioma cells transplanted into the rat brain. Tumor cell death, which correlated with the light propagation, was induced in tumor tissue. [ABSTRACT FROM AUTHOR]

This work presents a novel technique for the detection of oil aging in electrical transformers using a single mode optical fiber sensor based on surface plasmon resonance (SPR). The aging of insulating oil is a critical issue in the maintenance and performance of electrical transformers, as it can lead to reduce insulation properties, increase risk of electrical breakdown, and decrease operational lifespan. Many parameters are calculated in this study in order to examine the efficiency of this sensor like sensitivity (S), signal to noise ratio (SNR), resolution (refractive index unit) and figure of merit (FOM) and the values are for figure of merit is 11.05, the signal to noise ratio is 20.3, the sensitivity is 6.63, and the resolution is 3.01* 10 - 5 . [ABSTRACT FROM AUTHOR]

Modulating dark optical fiber vector soliton molecules are theoretically investigated in this work. An optical fiber modulation system that out of fiber laser cavity is employed as a simulation model, which can flexibly change orthogonal electric fields’ properties of original optical fiber vector solitons. We consider two cases for simulation, one is original orthogonal polarization modes have the same central wavelength in the frequency domain, the other is original orthogonal polarization modes have different central wavelengths. In the first case, modulated dark vector soliton molecules with two pulse peaks and two pulse dips, accompanied by two wavelengths can always be observed. While in the second case, optical spectra will split in orthogonal directions, and obvious temporal pulse oscillation will occur, when the projection angle changes. The results further explore modulating vector solitons that with unique characteristics, in out-cavity optical fiber modulation systems. [ABSTRACT FROM AUTHOR]

The human body synthesizes catecholamine neurotransmitters, such as dopamine and noradrenaline. Monitoring the levels of these molecules is crucial for the prevention of important diseases, such as Alzheimer's, schizophrenia, Parkinson's, Huntington's, attention-deficit hyperactivity disorder, and paragangliomas. Here, we have synthesized, characterized, and functionalized the BODIPY core with picolylamine (BDPy-pico) in order to create a sensor capable of detecting these biomarkers. The sensing properties of the BDPy-pico probe in solution were studied using fluorescence titrations and supported by DFT studies. Catecholamine sensing was also performed in the solid state by a simple strip test, using an optical fiber as the detector of emissions. In addition, the selectivity and recovery of the sensor were assessed, suggesting the possibility of using this receptor to detect dopamine and norepinephrine in human saliva. [ABSTRACT FROM AUTHOR]

This work proposes a simple and affordable technology for the manufacturing of a miniature end-face fiber-optic temperature sensor based on a Fabry–Perot interferometer formed from a transparent UV-curable resin. For the manufactured working prototype of the sensor, the sensitivity and operating temperature range were determined, and the methods for their enhancement were proposed. Due to its small size, the proposed type of sensor can be used in high-precision and minimally invasive temperature measurements, in biology for microscale sample monitoring, and in medicine during operations using high-power lasers. A microwave photonic method is proposed that enables the interrogation of the sensor without using an optical spectrum analyzer. [ABSTRACT FROM AUTHOR]

The article provides an overview of the known effects that influence the transmission of information over optical fiber and that arise as a result of lightning discharges: the electro-optical Kerr effect, the Faraday effect, the influence of ionizing radiation. It is indicated that there is preliminary empirical data according to which the magnetic field changes such an optical fiber parameter as attenuation. In order to verify these preliminary empirical data, further experimental studies of the supposed influence of the magnetic field on attenuation are proposed, for which it is necessary to build a laboratory installation. This article is also devoted to a comparison of various options for laboratory installations and the preliminary selection of a parameter for comparison. As a result of modeling two options for a laboratory installation and comparing them according to the accepted parameter, one of two installation options is selected.

In this paper, the extended simplest equation method is utilized to construct the novel exact optical solitons solutions of the perturbed time fractional Chen–Lee–Liu equation with conformable fractional derivative. The acquired optical solitons and other solutions are expressed via the rational functions, the trigonometric functions, and the hyperbolic functions; in addition to guaranteeing the existence of the acquired results, the constrain conditions are provided. Furthermore, to elucidate the magnitude of the proposed equation, various obtained solutions are plotted via two-dimensional (2D) and three-dimensional (3D) graphs using appropriate values of parameters. It is observed that the present technique is a powerful tool and efficient for finding the analytical solution for nonlinear differential equations of integer and fractional orders. [ABSTRACT FROM AUTHOR]

Occurrence of loess landslide has been more frequent due to the drastic global climate change, rapid expansion of human disturbances and continuous intensification of engineering activities. The activation and evolution mechanisms of the loess landslides under the rainfall are yet to be studied. In this paper, with reference to the Yangpoyao slope with seepage fissures under rainfall, an adjustable-angle landslide model test system is developed, integrating the rainfall simulation system, the measurement system and the data acquisition system, and the deformation development of the model, the rainfall infiltration, the change of water content and the destructive process of the model are monitored by the monitoring technology of multi-means and multi-methods throughout the course of the disaster. A distributed fibre-optic sensor system with the characteristics of continuity and high precision is used to monitor the temperature and strain within the slope model. The deformation evolution mechanism of fissured loess slopes under rainfall was elucidated through the observation of experimental phenomena and the analysis of the internal strain values of the soil, as measured by fibre optic sensors. The experimental results show that the collapse process of loess slopes can be categorised into three types, i.e. sinkhole collapse, block collapse and gully collapse, and that the deformation and damage patterns of the loess landslide model are mainly caused by shallow soil movement induced by erosion. Through the comparative analysis of the model test and the photographs of the field investigation, it is further demonstrated that the damage pattern shown in the physical model test is basically consistent with the slope condition of the real Yangpoyao slope, which provides a new theoretical reference for natural disaster prediction and management of loess slopes and landslides. [ABSTRACT FROM AUTHOR]

This article introduces a novel method that leads to the reduction of noise effects and improvement in the quality of phase image acquisition in noisy environments using quantitative phase microscopy. In this method, a motorized system was present at the sample location, which allowed the lateral movement of the sample in different directions. By capturing many phase images in different positions and averaging them, two final images corresponding to each wavelength were obtained. Finally, by averaging between the obtained thicknesses of the sample in two wavelengths, the final image with the less noise effect was obtained. To demonstrate the effectiveness of the proposed method, multiple images of an optical fiber recaptured in noisy condition using a motorized dual-wavelength quantitative phase microscope. The results indicate that the final image is closer to the ideal image with a noticeable reduction in noise. [ABSTRACT FROM AUTHOR]

Research results into the automating the processing of measurement data obtained from the Brillouin optical reflectometer, light guides containing various types of optical fibers are presented in this paper. By analyzing the parameters of the Mandelstam — Brillouin scatter obtained from Brillouin reflectograms, we can classify optical fibers in the studied telecommunication optical cables. This makes it possible to evaluate the change of the Brillouin frequency shift and determine the longitudinal fiber tension. The initial values of the Brillouin frequency shift and the profile of the Mandelstam — Brillouin scatter spectrum are different for each fiber type. The programs for automated processing of Brillouin reflectogram data are discussed. Estimation of the level of the back-reflected signal allows you to identify the factor, that had a predominant effect on the parameters of the Mandelstam — Brillouin scatter signal in the studied sections of optical fibers, and to compensate for the influence of temperature changes in the longitudinal strain distribution graphs. After that, we can plot a graph of the distribution of longitudinal strain along the fiber, caused precisely by mechanical influences on optical fibers. Conclusions about the accuracy of the estimates obtained by various algorithms, based on the accumulated experience in working with the presented programs are drawn.

Here, we present the concept of flat-field capillary-assisted nanoparticle tracking analysis for the characterization of fast diffusing nano-objects. By combining diffusion confinement and spatially invariant illumination, i.e., flat-fields, within a fiber-interfaced on-chip environment, ultra-long trajectories of fast diffusing objects within large microchannels have been measured via diffraction-limited imaging. Our study discusses the design procedure, explains potential limitations, and experimentally confirms flat-field formation by tracking gold nanospheres. The presented concept enables generating flat-fields in a novel on-chip optofluidic platform for the characterization of individual nano-objects for fundamental light/matter investigations or applications in bioanalytics and nanoscale material science.

Modern power grids are undergoing a significant transformation with the massive integration of renewable, decentralized, and electronically interfaced energy sources, alongside new digital and wireless communication technologies. This transition necessitates the widespread adoption of robust online diagnostic and monitoring tools. Sensors, known for their intuitive and smart capabilities, play a crucial role in efficient condition monitoring, aiding in the prediction of power outages and facilitating the digital twinning of power equipment. This review comprehensively analyzes various sensor technologies used for monitoring power transformers, focusing on the critical need for reliable and efficient fault detection. The study explores the application of fiber Bragg grating (FBG) sensors, optical fiber sensors, wireless sensing networks, chemical sensors, ultra-high-frequency (UHF) sensors, and piezoelectric sensors in detecting parameters such as partial discharges, core condition, temperature, and dissolved gases. Through an extensive literature review, the sensitivity, accuracy, and practical implementation challenges of these sensor technologies are evaluated. Significant advances in real-time monitoring capabilities and improved diagnostic precision are highlighted in the review. It also identifies key challenges such as environmental susceptibility and the long-term stability of sensors. By synthesizing the current research and methodologies, this paper provides valuable insights into the integration and optimization of sensor technologies for enhancing transformer condition monitoring and reliability in modern power systems. [ABSTRACT FROM AUTHOR]

Yttrium aluminum garnet (YAG)-based optical fiber is one of the research hotspots in the field of fiber lasers due to its combined advantages of a wide doping range of rare earth ions and the high mechanical strength of YAG material, as well as the flexibility and small size of the fiber structure. YAG-based optical fibers and related laser devices can be used in communication, sensing, medicine, etc. A comprehensive review of YAG-based optical fibers is provided in this paper. Firstly, the fabrication processes of YAG-based optical fibers are summarized and the structure and properties of fibers are classified and compared. Secondly, according to the optical wavelength regions, rare earth-doped YAG-based optical fibers for the applications of single-frequency and mode-locked fiber lasers are summarized. Lastly, the development challenges in both the fabrication and applications of YAG-based optical fibers are discussed. [ABSTRACT FROM AUTHOR]

Blood vessel imaging provides crucial information for physiological monitoring and disease diagnosis. Optical‐resolution photoacoustic microscopy (PAM) is gaining intense attention in high‐resolution in vivo imaging of blood vessels. However, its applicability in clinical settings is hindered by the requirement of bulky and costly pulsed lasers as well as complex alignment procedures. Here, as a novel approach to high‐quality and cost‐effective microvasculature imaging, a dual‐wavelength fiber‐coupled laser diode‐based PAM (FC‐LD‐PAM) system is demonstrated on the mouse ear and brain in vivo. Furthermore, assisted with a deep learning method, the proposed technique effectively combines the advantages when using both small and large core‐size multimode fibers—successfully enhances the resolution of blurry mouse microvascular images obtained using a large core‐size fiber, revealing fine details that are comparable to those achieved using a small core‐size fiber; significantly reduces the overall time for data acquisition up to fourfold, improving the efficiency significantly in the imaging process. In addition, the proposed approach can achieve accurate and high‐resolution mapping of oxygen saturation in vivo, providing functional insight on living tissue. Therefore, the FC‐LD‐PAM can serve as a translational tool for high‐resolution imaging with enhanced accessibility and versatility in the biomedical field. [ABSTRACT FROM AUTHOR]

Fiber optic surface plasmon resonance (SPR) sensor based on copper and tungsten disulfide is presented experimentally. The method of wavelength interrogation is used to analyze the sensor. Outcomes of thicknesses of these materials on the sensitivity of the sensor have been shown in detail. The presence of tungsten disulfide layer of certain thickness in the copper-based sensor has been shown to improve the sensitivity. The SPR sensor with 40 nm thick copper-10 nm thick tungsten disulfide layers exhibits highest sensitivity. [ABSTRACT FROM AUTHOR]

The performance parameters of a type of sensing device for temperature measurement are determined experimentally and theoretically using a technique of excitation of surface plasmon resonances in optical fibers. The developed device consists of a tapered optical fiber coated with silver nanoparticles (AgNPs) that were obtained using the green synthesis technique. For the verification of the experimental results, the transference matrix model, the Drude model and the theory of surface plasmon resonance in the Kretschmann configuration was used. During the investigation it is verified that the transmittance measured as a response signal of the optical fiber is in accordance with the theoretical results obtained from the mathematical modeling. To determine the performance parameters of the device developed for temperature measurement, the sensitivity S and the figure of merit FOM of the device were determined from the rate of change of the plasmon resonance wavelength shift as a function of the temperature gradients and transmission spectra at the output of the tapered optical fiber for different temperature values, observing a red shift of the plasmonic resonance wavelength with decreasing temperature. For the case of FOM, this was determined indirectly using S and Full Width at Half Maximum FWHM. Experimental results reveal that the developed devices exhibit sensitivities in the order of -0.18 nm/°C to -0.52 nm/°C with excellent reproducibility, while the FOM is in the order of 1.7 × 10− 2 °C− 1 to 2.4 × 10− 2 °C− 1. Theoretical and experimental results reveal that the sensitivity of the sensor presents a dependence on the geometrical parameters of the device, the nature of the coating and the surface of the device. [ABSTRACT FROM AUTHOR]

In this work, the (2+1)-dimensional chiral nonlinear Schrödinger equation that describes about quantum field concept in physics and other physical sciences are studied and solved by utilizing the two modern techniques including the polynomial expansion method and the Sardar sub-equation method. We attained different types of soliton solutions that had been applications in different fields of mathematical sciences. The behaviours of attained solutions are periodic, singular and v-shaped soliton solutions. Furthermore, we have investigated the stability of the obtained results. Also, the 3D, 2D, and contour graphics are displayed for the better understanding of the dynamical behaviour of various waves structures extensively. The techniques applied in this article are not used in this model in literature so we say that our findings are new that summarize the novelty of work. The utilize model has applications in physics related phenomenon also obtained results highly valuable in various branches of sciences specially in the transmission of fiber optical. [ABSTRACT FROM AUTHOR]

A fiber-based surface plasmon resonance (SPR) sensor is investigated in this study. Initially, a D-shaped optical fiber is studied under different types and brands of light sources, optical spectrometers, and polarizing angles. The best stability with low noise is a supercontinuum light source with Avantes spectrometer. Using the polarizer controller to tune the width and dip shows the minimum absorption point when waveplates are set at 90°, 0°, and 45°. The temperature effects are recognized as shifts in absorption ranging from 30 to 60 °C for fiber-based SPR (with and without a polarizer controller). In the photoelastic effect, the sensor shows significant variation according to the applied load, with a maximum sensitivity of 1.05 nm/g at 5 g weight. Stability, response time, and selectivity are also discussed. Results are used to analyze the plasmonic sensor efficiency for Hg ions detection. It appears that there is a lack of information regarding the light types and polarization angles within a D-shaped fiber for Hg ions SPR sensor. As of now, there seems to be no published literature that has thoroughly explored this topic under different conditions. [ABSTRACT FROM AUTHOR]

According to its complex properties like ergodicity, unpredictability, and sensitivity to its initial states, chaotic systems are attracting more and more attention and are frequently employed for security purposes. In this work, for the first time in our knowledge, a secure optical communication based on optical chaos with pre-, post-, and symmetric dispersion compression fiber (DCF) configurations was designed and implemented for 10 Gb/s non-return-to-zero (NRZ) utilizing OptiSystem software 7.0. It was found that the optical chaos resulted a degradation in system length of about 61%. To reduce this degradation, DCF was inserted. When comparing three DCF configurations, the pre-DCF outperforms the post-DCF and the symmetric DCF. When post- and symmetric DCF are compared, the former is found to be superior to the latter. Thus, using pre-DCF, a high-capacity, secure system with an acceptable distance and an effective cost was obtained. [ABSTRACT FROM AUTHOR]

This paper presents the construction of an innovative high-temperature sensor based on the optical principle. The sensor is designed especially for the measurement of exhaust gases with a temperature range of up to +850 °C. The methodology is based on two principles-luminescence and dark body radiation. The core of this study is the description of sensing element construction together with electronics and the system of photodiode dark current compensation. An advantage of this optical-based system is its immunity to strong magnetic fields. This study also discusses results achieved and further steps. The solution is covered by a European Patent. [ABSTRACT FROM AUTHOR]

A new cost-effective radiometer has been designed, built, and tested to measure direct normal solar irradiance (DNI). The proposed instrument for solar irradiance measurement is based on an optical fiber as the light beam collector, a semiconductor photodiode to measure the optical power, and a calibration algorithm to convert the optical power into solar irradiance. The proposed radiometer offers the advantage of separating the measurement point, where the optical fiber collects the solar irradiation, from the place where the optical power is measured. A calibration factor is mandatory because the semiconductor photodiode is only spectrally responsive to a limited part of the spectral irradiance. Experimental tests have been conducted under different conditions to evaluate the performance of the proposed device. The measurements confirm that the proposed instrument performs similarly to the expensive high-accuracy pyrheliometer used as a reference. [ABSTRACT FROM AUTHOR]

To facilitate temperature detection in industrial production settings, an optical fiber temperature transmitter was developed utilizing fluorescence lifetime as its basis. Comprising an upper computer, fiber optic temperature transmitter, and optical fiber probe, the system incorporates a scalable fluorescence detection module. Real‐time temperature calculation is achieved through a microcontroller based on the fluorescence lifetime, with results transmitted to the upper computer, the optical fiber sensor exhibits a resolution of 0.01°C and an accuracy of ±0.3°C. [ABSTRACT FROM AUTHOR]

This paper simulates the relative performance of various artificial intelligence (AI) techniques when applied to nonlinear distortion compensation in wavelength division multiplexing (WDM) optical communication systems. These procedures are less complex than state-of-the-art compensation methods and do not necessitate prior knowledge about the properties of data in neighboring WDM channels, which can be practically challenging. In this study, Neural Networks (NNs) were integrated into both the transmitter and receiver sections of 3- and 5-channel WDM systems, and the resulting enhancement in performance (Q-factor) was assessed across varying levels of fiber nonlinearities. While the NN stage enhances the system performance, the improvement decreases as expected with the channel number and γ . Next, two-stage architectures that employ a transmitter side NN together with a classifier at the receiver side were modeled. For the systems examined in this paper simple decision tree structures, boosting, forests, extra trees, and multi-layer perceptron (MLP) classifiers all yielded enhanced system performance compared to simple chromatic dispersion compensation (CDC) with the only exception being Ada boosting which decreased the Q-factor for γ = 14 W - 1 k m - 1 . The outcomes of these investigations show that the most effective performance in highly nonlinear WDM systems is attained by employing two-stage systems, with the incorporation of random forest or extra tree AI methods at the receiver side yielding the highest results. [ABSTRACT FROM AUTHOR]

Optical fibers play a crucial role in various fields, including free-space optical communication and quantum communication. The beam coming out of the fiber facet, unfortunately, has a very high divergence angle. This divergence can be problematic, especially when coupling the light into free space or to other optical components that require collimated beams. The beam divergence can be reduced and the beam can be shaped with the help of suitable collimating optics, which serves as the coupler to couple light between fiber and free-space. However, these traditional collimating optics consists of lenses that are generally spherical in nature and are limited in their ability to shape the phase of the beam as they can provide only a spherical phase to the incoming Gaussian beam from the fiber. This limitation can be overcome by using metasurfaces, which can shape the phase of the beam in a more tailored manner. In this paper, we have designed the metalens that can be directly formed on the fiber facet and can collimate the 1550 nm beam coming out of the single mode fiber facet with the use of two different kinds of cylindrical metalens. These metalens can reduce the beam divergence and can achieve diffraction limited collimation while maintaining a transmittance of ≥ 95 %. [ABSTRACT FROM AUTHOR]

Currently, there are many enterprises involved in extracting and processing of primary raw materials. The danger of working in this industry consists in the formation of cracks in rocks of the pit side slopes, which can lead to destruction. This article discusses the existing systems for monitoring the pit collapse prevention. The most promising is the use of systems with fiber-optic sensors. However, use of these systems is associated with some difficulties due to high costs, low noise immunity, and in some cases, the requirement for additional equipment to improve the reliability of measurements. A completely new method of processing the data from a fiber-optic sensor that simplifies the design and reduces the cost of the device is proposed considering the experience of previous developments. The system uses artificial intelligence, which improves the data processing. The theoretical part is dedicated to the development of foundations, and the analysis of the nonlinear properties of the physical and mathematical model of optical processes associated with the propagation of an electromagnetic wave in a fiber-optic material was developed. The results of experimental and theoretical applied research, which are important for the development of fiber-optic systems for monitoring the pit collapse prevention, are presented. The dependences of optical losses and the number of pixels on the dis-placement were obtained. The accuracy of the method corresponds to the accuracy of the device by which it is calibrated and is 0.001 mm. The developed hardware-software complex is able to track the rate of changing the derivative of the light wave intensity in time, as well as changing the shape of the spot and transition of pixels from white to black. [ABSTRACT FROM AUTHOR]

The digital twin was created and a prototype of the power supply system with power transmission via optical fiber was manufactured. This technology belongs to the field of optical, wireless and fiber optic power transmission (OWPT). Verification of correctness of the digital twin operation was carried out. The task of achieving the maximum possible efficiency of the system at varying load was solved. Its value amounted to 14%. The operability of the search algorithm of the double differentiation system developed for this purpose is shown. The principle of its operation consists in the change of optical energy synchronously with the change of load resistance. This allows to reduce losses in the primary and secondary energy converters. In the area of optimal regulation, the algorithm provides the minimum power supply level necessary for the operation of secondary devices, at which the maximum possible efficiency of the whole power supply system is achieved. The presented work is a part of the program of creating an end-to-end intelligent system of the full production cycle of the product, starting from the design of structures of opto- and photovoltaic converters (PC), up to the manufacture of systems adapted to individual customer requirements. [ABSTRACT FROM AUTHOR]

Tissue imaging is crucial in oral cancer diagnostics. Imaging techniques such as X-ray imaging, magnetic resonance imaging, optical coherence tomography (OCT) and computed tomography (CT) enable the visualization and analysis of tissues, aiding in the detection and diagnosis of cancers. A significant amount of research has been conducted on designing OCT probes for tissue imaging, but most probes are either heavy, bulky and require external mounting or are lightweight but straight. This study addresses these challenges, resulting in a curved lightweight, low-voltage and compact handheld imaging probe for oral soft tissue examination. To the best of our knowledge, this is the first curved handheld OCT probe with its shape optimized for oral applications. This probe features highly compact all-fiber optics with a diameter of 125 μm and utilizes innovative central deflection magnetic actuation for controlled beam scanning. To ensure vertical stability while scanning oral soft tissues, the fiber was secured through multiple narrow slits at the probe's distal end. This apparatus was encased in a 3D-printed angular cylinder tube (15 mm outer diameter, 12 mm inner diameter and 160 mm in length, weighing < 20 g). An angle of 115° makes the probe easy to hold and suitable for scanning in space-limited locations. To validate the feasibility of this probe, we conducted assessments on a multi-layered imaging phantom and human tissues, visualizing microstructural features with high contrast. [ABSTRACT FROM AUTHOR]

Detecting hydrogen leaks remains a pivotal challenge demanding robust solutions. Among diverse detection techniques, the fiber-optic method distinguishes itself through unique benefits, such as its distributed measurement properties. The adoption of hydrogen-sensitive materials coated on fibers has gained significant traction in research circles, credited to its operational simplicity and exceptional adaptability across varied conditions. This manuscript offers an exhaustive investigation into hydrogen-sensitive materials and their incorporation into fiber-optic hydrogen sensors. The research profoundly analyzes the sensor architectures, performance indicators, and the spectrum of sensing materials. A detailed understanding of these sensors' potentials and constraints emerges through rigorous examination, juxtaposition, and holistic discourse. Furthermore, this analysis judiciously assesses the inherent challenges tied to these systems, simultaneously highlighting potential pathways for future innovation. By spotlighting the hurdles and opportunities, this paper furnishes a view on hydrogen sensing technology, particularly related to optical fiber-based applications. [ABSTRACT FROM AUTHOR]

This article extracts analytical solutions of the Fokas-Lenells equation describing pulse propagation in optical fibers and presents a comprehensive analysis of the analytical solutions. This paper focuses on deriving analytical, non-perturbative solutions for the Fokas-Lenells equation by reducing it to a system of ordinary differential equations using the Lie symmetry method. Three generators for the Lie algebra are obtained, and three reductions are explored by combining vector generators. These algebraic structures provide a powerful framework for simplifying complex mathematical and physical problems by revealing underlying symmetries and patterns. The graphical representations of obtained solutions are rendered. Besides, the influence of parameters within the equation on the behavior of the solutions has been demonstrated in the figures. These results contribute to a deeper understanding of the Fokas-Lenells equation and have implications in various fields of physics and engineering. [ABSTRACT FROM AUTHOR]

Glass ceramics (GCs) containing PbS quantum dots (QDs) are prepared for temperature sensing. Broadband emissions are detected in the GCs when PbS QDs are precipitated from the glasses, and emissions centers are modulated from 1250 nm to 1960 nm via heat treatments. The emission centers of GCs exhibit blue-shifts when environment temperatures increase from room temperature to 210 °C. Importantly, the shift values of emission centers increase linearly with the test temperature, which is beneficial for applications in temperature sensing. A temperature sensor based on PbS QDs GC is heat-treated at 500 °C for 10 h, possesses the highest sensitivity of 0.378 nm/°C, and exhibits excellent stability and repeatability at high temperatures (up to 210 °C). Moreover, GC fibers are fabricated by using the GCs as the fiber core. The sensitivity of the temperature-sensing sensor of the GC fibers is also demonstrated and the sensitivity is as high as 0.558 nm/°C. The designed PbS QDs GCs provide a significant materials base for the manufacturing of fluorescent temperature sensors and the GC fibers offer significant opportunities for temperature detection in complex, integrated and compact devices. [ABSTRACT FROM AUTHOR]

This paper examines the quantitative and qualitative situation of the current fixed and mobile Internet and its expected future. It provides a detailed insight into the past, present, and future of the Internet along with the development of technology and the problems that have arisen in accessing and using broadband Internet. First, the number of users and penetration rate of the Internet, the various types of services in different countries, the ranking of countries in terms of the mean and median download and upload Internet data speeds, Internet data volume, and number and location of data centers in the world are presented. The second task introduces and details twelve performance evaluation metrics for broadband Internet access. Third, different wired and wireless Internet technologies are introduced and compared based on data rate, coverage, type of infrastructure, and their advantages and disadvantages. Based on the technical and functional criteria, in the fourth work, two popular wired and wireless Internet platforms, one based on optical fiber and the other based on the 5G cellular network, are compared in the world in general and Australia in particular. Moreover, this paper has a look at Starlink as the latest satellite Internet candidate, especially for rural and remote areas. The fifth task outlines the latest technologies and emerging broadband Internet-based services and applications in the spotlight. Sixthly, it focuses on three problems in the future Internet in the world, namely the digital divide due to the different qualities of available Internet and new Internet-based services and applications of emerging technologies, the impact of the Internet on social interactions, and hacking and insecurity on the Internet. Finally, some solutions to these problems are proposed. [ABSTRACT FROM AUTHOR]