Light Guides Research Articles

RECOMMENDATIONS ON THE URBAN NETWORK FOTL STRUCTURE WITH THE LOWEST POSSIBLE LEVEL OF DISTORTION OF INFORMATION AND CONTROL ILCF-SIGNALS

The article studies the problem of construction of subscriber branched networks xPON/MAN/RoF, on the base of fiber-optic transmission lines, with the possibility of non-relational control. Namely, enabling transmission of control information as a part of subscriber signal. It is proposed to use instantaneous wavelength change function of the optical signal (ILCF)as the control information with parametric characteristics. A method of modeling such segments was offerred, nature of ILCF was analyzed, and recommendations on inclusion of EDFA light guides and methods of pumping to them from the point of view of maintaining positive chirp for the information-control ILCF signal were made. It was assumed that ensuring positive chirp will minimize distortion of the latter during its transmission. It is concluded that branching has significant effect on ILCF. Recommended parameters of segments for different degrees of their branching are also obtained as well.

Development Of An Endoscopic, Absorption Corrected And Calibrated OH Laser Induced Fluorescence Probe System for High Pressure Combustion Diagnostics

We present the design and preliminary results of an endoscopic OH laser-induced fluorescence (LIF) system that is capable of acquiring 1D-line measurements in high pressure combustion processes within large-scale test facilities. The system can be exploited to acquire line-of-sight OH-chemiluminescence images and absorption corrected absolute OH-species concentration from which additionally temperature distribution can be extracted in case of lean mixtures in chemical equilibrium. Different critical components, such as light guides for high power UV laser pulses and flexible UV image guides, were first tested and characterized in a laboratory setup. Optimization regarding pulse energy and beam quality led to the selection of an 1m long hollow core fiber for laser light delivery as a central element for the experimental setup despite high losses caused by bending the fiber. The image transfer is accomplished by a 7m long flexible UV image bundle, which is preferred to the use of a rigid borescope in harsh environments. We designed the endoscopic UV optics using readily available parts and achieved an approximated image resolution of 21.6 line pairs/mm. Additionally, post-processing methods, such as flat-field correction, can improve the image quality substantially and remove the pixilation effect of the fiber bundle structure nearly completely. To validate the complete system, probe-based qualitative OH-LIF measurements were performed in a well-known laminar flame of a matrix burner, which serves as a mock-up for anticipated applications in an industrial test environment with a technology readiness level (TRL) greater than 4. The final step consists of the integration of the miniaturized optics into a cooled probe system which protects the sensitive optics against the harsh environment of an aero-engine sector combustor. For this purpose, two probe systems were designed to include, on the one hand, the endoscope optics together with the fiber image bundle end tip and, on the other hand, the laser emitting and receiving system for performing an absorption measurement needed to quantify the recorded LIF signal.

Design Of Automatic Lighting Instructions Based On Pir Gen 3 Sensors for Physics Learning in The Electronics Skills Course

This research produces an automatic light physics demonstration tool based on a PIR sensor in the Electronics Skills course. This type of research is development research which refers to the 4-D model according to Thiagarajan with 4 stages including the definition, design, development and dissemination stages. This research was tested in the Physics Education Study Program. Data collection techniques in this research include observation, interviews, and questionnaires. The data analysis technique used is descriptive statistical analysis. The results of this research obtained several findings including: (1). The product is a PIR sensor-based automatic light electrical circuit demonstration tool; (2). The feasibility test of teaching aids with an average rating of 33.33% Agree (S) and 66.67% Strongly Agree (SS), and the feasibility test of teaching aids with an average rating of 51.85% Agree (S) and 48.15% Strongly Agree (SS). Test the readability of students' responses to teaching aids and teaching aid guides with an average rating of 3% Disagree (TS), 43% Agree (S) and 54% Strongly Agree (SS). Based on the test results, it can be concluded that the PIR sensor-based automatic light electrical circuit teaching aids and guides are suitable for use in physics learning

Study of silicon photomultipliers for the readout of a lead/scintillating-fiber calorimeter

The KLOE electromagnetic calorimeter is expected to be reused in the Near Detector complex of the DUNE experiment at Fermilab. The possible substitution of traditional Photomultiplier Tubes (PMTs) with Silicon Photomultipliers (SiPMs) in the refurbished calorimeter is the object of this investigation. A block of the KLOE lead-scintillating fiber calorimeter has been equipped with light guides and external trigger scintillators. The signals induced by cosmic rays and environmental radioactivity have been collected by SiPM arrays on one side of the calorimeter, and by conventional PMTs on the opposite side. Efficiency, stability, and timing resolution of SiPMs have been studied and compared with KLOE-PMTs performance. Conclusions about the convenience of substituting PMTs with SiPMs are drawn.

Quantum Sensing and Light Guiding with Fluorescent Nanodiamond‐Doped PVA Fibers (Advanced Optical Materials 14/2024)

Quantum Sensing and Light Guiding with Fluorescent Nanodiamond‐Doped PVA Fibers (Advanced Optical Materials 14/2024)

Design and Application of Liquid Silicone Rubber Light Guide in Compact Automotive Headlamps

Traditional car headlights use halogen or high-intensity discharge (HID) lamps paired with a reflector cup, fisheye lens, and shading plate to comply with ECE112B (Headlamps with an Asymmetrical Passing Beam) regulations. This design has issues such as large and bulky volumes, and it sacrifices optical efficiency due to the shading plate. This paper proposes a solution using an LED light source coupled with a Liquid Silicone Rubber-Light Guide (LSR-LG) for compact automotive low-beam headlights. By employing the principle of total internal reflection, the light beam is confined within the LSR-LG to reduce the volume of the car lamp. Simultaneously, optimized the structure and adjusted the light distribution. In the prototype measurements, the LED combined with the LSR-LG in the compact automotive headlamps module exhibited light intensities of 11,942 cd, 12,898 cd, and 298.2 cd at measurement points 75 R, 50 R, and BR, respectively, by ECE R112B standards. Simultaneously, the design effectively reduced the car lamp module’s volume to 90.63 mm × 164.53 mm × 73.37 mm. This design offers advantages such as energy efficiency, lightweight construction, and compact size. It also complies with ECE R112B regulations, showing promising potential as an excellent choice for the next generation of automotive low-beam headlights.

Impact of optical fiber-based photo-activation on dental composite polymerization

ObjectivesThe study aimed to introduce a novel two-step optical fiber-based photo-activation of dental resin-based composites (RBCs) for reducing polymerization shrinkage stress (PSS). MethodsProposed protocol design – in the first step, two flexible plastic optical fibers connected to a dental light curing unit (LCU), were used as light guides inserted into the filling to initiate low-irradiance polymerization from within; in the second step, fibers were extracted and remaining voids were filled with RBC, followed by conventional high-irradiance curing to finalize polymerization. Three bulk-fill RBCs were tested (Beautifil-Bulk Restorative, Filtek Bulk-fill Posterior, Tetric PowerFill) using tooth cavity models. Three non-invasive examination techniques were employed: Digital Holographic Interferometry, Infrared Thermography, and Raman spectroscopy for monitoring model deformation, RBC temperature change, and degree of conversion (DC), respectively. A control group (for each examined RBC) underwent conventional photo-activation. ResultsThe experimental protocol significantly reduced model deformation by 15 – 35 %, accompanied by an 18 – 54 % reduction in RBC temperature change, emphasizing the impact of thermal shrinkage on PSS. Real-time measurements of deformation and temperature provided indirect insights into reaction dynamics and illuminated potential mechanisms underlying PSS reduction. After a 24-hour dark-storage period, DC outcomes comparable to conventional curing were observed, affirming the clinical applicability of the method. ConclusionsProtocol involving the use of two 1.5 mm fibers in the first step (300 mW/cm2 x 10 s), followed by a second conventional curing step (1000 mW/cm2 x 10 s), is recommended to achieve the desired PSS reduction, while maintaining adequate DC and ensuring efficient clinical application. Clinical SignificanceObtained PSS reduction offers promise in potentially improving the performance of composite restorations. Additionally, leveraging the flexibility of optical fibers improves light guide approach for restorations on posterior teeth. Meanwhile, implementation in clinical practice is easily achievable by coupling the fibers with commercial dental LCUs using the provided plastic adapter.

Thermally Induced Reversible Changes in the 7200 cm–1 Absorption Band in a Fiber Light Guide with a High Concentration of OH Groups in the Core

Thermally Induced Reversible Changes in the 7200 cm–1 Absorption Band in a Fiber Light Guide with a High Concentration of OH Groups in the Core

High Refractive Index Carbonized Polymer Dots Acting as Light Scattering Units in Nanocomposites for Full‐Screen Light Guide Plate

AbstractThe full‐screen mobile phone can be fabricated by integrating the camera beneath the screen, which needs the nanocomposite light guide plate (nano‐LGP) with exceptional transparency and light‐guiding properties simultaneously. Choosing an appropriate nanoparticle with a high refractive index and exceptional compatibility within the polymer matrix is crucial for producing the nano‐LGP. In this study, the high refractive index carbonized polymer dots (HRI‐CPDs) are synthesized through the solvothermal treatment, achieving a refractive index value of 1.7220 at 450 nm. Subsequently, the modified HRI‐CPDs (mHRI‐CPDs)/polymethyl methacrylate (PMMA) nanocomposites are fabricated by copolymerizing the mHRI‐CPDs with methyl methacrylate . Due to the high visible light transmittance and Rayleigh scattering characteristics when light passes through the nanocomposites, this kind of nanocomposites is suitable for serving as nano‐LGPs. The potential of carbonized polymer dots as light‐scattering unit is originally explored to improve surface illuminance and uniformity of nano‐LGPs. The best‐performing 4.3‐inch LGP with 1.0 wt.% doping content shows 15.8 times higher surface illuminance and 2.1 times higher uniformity than pure PMMA. This new type of LGP based on mHRI‐CPDs/PMMA nanocomposite holds tremendous promise in conjunction with advanced liquid crystal display technology.

Biomimetic Curved Artificial Compound Eyes: A Review

Natural compound eyes (NCEs) are the most abundant and successful eye designs in the animal kingdom. An NCE consists of a number of ommatidia, which are distributed along a curved surface to receive light. This curved feature is critical to the functions of NCE, and it ensures that different ommatidia point to slightly different directions and thus enables panoramic vision, depth perception, and efficient motion tracking while minimizing aberration. Consequently, biomimetic curved artificial compound eyes (BCACEs) have garnered substantial research attention in replicating the anatomical configuration of their natural counterparts by distributing ommatidia across a curved surface. The reported BCACEs could be briefly categorized into 2 groups: fixed focal lengths and tunable focal lengths. The former could be further subcategorized into simplified BCACEs, BCACEs with photodetector arrays within curved surfaces, and BCACEs with light guides. The latter encompasses other tuning techniques such as fluidic pressure modulation, thermal effects, and pH adjustments. This work starts with a simple classification of NCEs and then provides a comprehensive review of main parameters, operational mechanisms, recent advancements, fabrication methodologies, and potential applications of BCACEs. Finally, discussions are provided on future research and development. Compared with other available review articles on artificial compound eyes, our work is distinctive since we focus especially on the “curved” ones, which are difficult to fabricate but closely resemble the architecture and functions of NCEs, and could potentially revolutionize the imaging systems in surveillance, machine vision, and unmanned vehicles.

Определение разновидностей оптических волокон и ранняя диагностика их физического состояния на основе анализа характеристик рассеяния Мандельштама–Бриллюэна

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.

Characteristics of optoelectronic discrete displacement converters with hollow and fiber light guides

This article discusses the issues of optoelectronic discrete converters of any type - longitudinal or transverse movement of the external modulating body. In connection with the development of such important sectors of the economy as mechanical engineering, metallurgy, oil and gas, chemical, industrial, construction, food industry and others, it is important to provide them with modern discrete displacement transducers, which allow monitoring and managing such important quantities as liquid level, speed and flow flows of gases and liquids, as well as automative the processes of automatic accounting of piece goods, products, goods, blanks and semifinished products, which allows you to objectively analyze the economic activities of enterprises and plan their further development. The variety of specific features of monitoring and control objects put forward a set of requirements for discrete converters of object parameters: high sensitivity, accuracy, reliability, sufficient noise immunity, manufacturability. An analysis of existing discrete optoelectronic displacement transducers shows that to solve the above problems for monitoring and control, optoelectronic discrete displacement transducers based on hollow and fiber light guides are the most acceptable. In this regard, the improvement and development of optoelectronic discrete displacement transducers based on hollow and fiber light guides is an urgent task.

Optimal fiber-optical sensing element selection on multimode interferometer

The paper presents the results of model and experimental search for optimal configuration of sensing element based on fiber-optical multimode interferometer with intermode interference in the phase-amplitude filter. Simulation results are presented. Based on them, combinations of multimode fiber light guides with single-mode ones are selected, the most suitable for constructing the sensitive part. Laboratory tests of the selected configurations were carried out. The requirements for the necessary components have been developed. The dynamic characteristics of the sensing elements are obtained depending on the variable parameters for different methods of welding fiber light guides.

INCREASING THE EFFICIENCY OF LASER MEDICAL DEVICES WITH FIBER-OPTIC LIGHT GUIDES UNDER THE CONDITIONS OF EXTERNAL THERMAL EFFECTS

Study of the influence of the controlled parameters of the electron beam (the density of the thermal effect Fn and the speed of movement (scanning) along the treated surface V) on such important parameters of the quality of the end surfaces of the light guides as their cleanliness and micro-roughness, which have a significant impact on the transmission coefficient of IR radiation kl, are now limited. Therefore, the purpose of this work is to establish the regularities of the influence of the controlled parameters of the electron beam, to determine the optimal ranges of their application, which do not lead to the destruction of the treated end surfaces of light guides made of optical glass and maximize the IR transmission coefficient by increasing their purity and reducing micro-roughness, which makes it possible to increase the efficiency of devices in conditions of external thermal effects.The study of the thermal effect of an electron beam on optical glass elements was carried out on specialized electron beam equipment protected by Ukrainian patents. Modern methods of physical and chemical analysis were used to conduct experimental research. The obtained experimental data were processed in dialogue mode and in real time on a PC using modern methods of mathematical statistics and standard application programs. At the same time, the relative measurement error of the considered parameters does not exceed 5...7 %.Experimental studies were carried out and optimal ranges of electron beam parameter changes were established (thermal action density Fn = 3∙106...7∙108 W/m2; scanning speed V = 6∙10-3...4∙10-2 m/s), within in which the most significant improvement in the quality parameters of the processed end surfaces of light guides is observed (increasing the cleanliness of the surfaces and reducing their micro-roughness), which leads to an increase in the spectraltransmittance of IR radiation. As a result, the maximum allowable range of propagation of laser radiation in light guides increases and provides better diagnostics, therapeutic and surgical treatment, which contributes to increasing the efficiency of laser medical devices, especially when they are operated taking into account external thermal effects.

СТАН І ПЕРСПЕКТИВИ РОЗВИТКУ БІЛИХ СВІТЛОДІОДІВ З ВИПРОМІНЮВАННЯМ, НАБЛИЖЕНИМ ДО ПРИРОДНОГО

Innovative technologies for the production of modern LEDs have allowed leading manufacturers (Seoul Semiconductor, Samsung, Cree) to develop their own ways of producing highly efficient white LEDs characterised by radiation parameters close to natural light. Modern LED light source development technologies have led to a sharp decrease in the use of white light guides with a colour rendering index in the range of 70-75, while the new most efficient LEDs have a colour rendering index of at least 80, and LEDs with a colour rendering index of more than 90 are becoming more widely used. LEDs with a correlated colour temperature in the range of 3000-4500 K, which were not as commonly used before due to their lower efficiency, have become more widespread. To create energy-efficient lighting, it is now considered important to create LED lighting devices with a spectral composition of radiation close to white natural light, as it is the most acceptable for improving the psycho-physiological state of a person and adequate perception of the environment. The most comfortable and safe for humans is the value of the correlated colour temperature of light close to 4000-4500 K and the colour rendering index of more than 90 units. Leading lighting companies are successfully working on solving this problem. This paper analyses ways to improve the luminous efficiency and colour rendering index of white LEDs used by leading manufacturers of modern LEDs. The most efficient white LEDs with a colour rendering index in the range of 93-96 and a luminous efficiency of 105-200 lm/W are considered. In the face of fierce competition, leading manufacturers are addressing the issue of improving the quality of LED lighting equipment in their own ways, which ensures the continuous development of LED technologies. The maximum theoretically determined spectral efficiencies of white LEDs are about 370 lm/W, which may indicate possible significant achievements and significant prospects for the further development of LED lighting technology.

Quantum Sensing and Light Guiding with Fluorescent Nanodiamond‐Doped PVA Fibers

AbstractFluorescent nanodiamonds (FNDs) containing quantum defects enable the optical measurement of electromagnetic fields and temperature and are among the most developed nanoscale quantum sensors today. Yet, for many applications in biomedicine and beyond, FNDs must be integrated into biocompatible substrates that preserve FND sensitivity and bring FNDs within nanoscale distance of their sensing target. At the same time, the high excitation light intensity required for most quantum sensing protocols remains a major challenge for applications in biomedicine. Here, it is shown that FNDs embedded in polyvinyl‐alcohol (PVA) fibers are a powerful 3D platform for nanoscale quantum sensing via light guiding. First, it is demonstrated that biocompatible PVA fibers can guide light to excite FNDs >10 µm from the excitation beam. Using this light‐guiding‐enabled excitation, optically detected magnetic resonance (ODMR) and T1 spin relaxometry measurements are performed using the nitrogen‐vacancy (NV) center in FNDs. Through ODMR thermometry, it is shown that light‐guiding‐enabled excitation mitigates light‐induced heating. Finally, the quantum sensing capability of the platform is established by detecting paramagnetic gadolinium in a dry and aqueous environment using T1 relaxometry of the NV center in FNDs. These results pave the way for light‐guiding‐enabled optical quantum sensing in biomedicine using nanodiamond‐doped biosubstrates.

Study of Transmission Efficiency and Energy of a Light Beam in a Mirrored Hollow Tubular Light Guide

Urgent need to reduce emissions of carbon and other harmful substances in order to combat climate change is becoming more acute every year. Research presented in this work has the main goal of drawing additional attention to the technology of delivering daylight to rooms with constant presence of people, animals, and plants, which allows us to relieve some of the problems of energy and environment, for example, by reducing volume of electric lighting. This paper presents a detailed study of efficiency of light beam passing through a mirrored hollow tubular light guide, on basis of which the derived mathematical dependencies, calculation tables, necessary for practical work when modelling energy-efficient lighting systems, based on mirrored hollow tubular light guides, are presented. In addition, energy levels of the light flux were studied, as a result the energy efficiency resources of lighting systems were identified and directions for possible practical application of these resources formulated.

Generation of Supercontinuum in a Nonlinear Fiber Light Guide. Controlling the Raman Soliton Wavelength by Controlling the Polarization State of the Pump Pulse

Generation of Supercontinuum in a Nonlinear Fiber Light Guide. Controlling the Raman Soliton Wavelength by Controlling the Polarization State of the Pump Pulse

CALIBRATION OF 122 SENSL MICROFJ-60035 SIPMS AND THE REDUCTION OF OPTICAL CROSS-TALK DUE TO COUPLED LIGHT GUIDES

Recent silicon photomultipliers (SiPMs) boast excellent production quality, eliminating the need for individual breakdown voltage calibration. We present measurements of cross-talk probability and relative gain for 122 SensL MicroFJ-60035-TSV SiPMs. These semiconductor photosensors have replaced photomultiplier tubes in many applications due to their single-photon resolution, insensitivity to magnetic fields, robustness, and cost-effective photon detection at lower voltages. Light guides expand SiPMs' small photosensitive area, and optical coupling reduces cross-talk probability compared to bare sensors at nominal bias voltage, as demonstrated in this study.

An automation of the detection processes of the strain characteristics of optical fibers, classification of their varieties and identification the influence factor according to Brillouin reflectograms

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.