Optical Fiber Research Articles

Construction of highly active photocatalytic interfaces through light field modulation and photo-deposition of Pd sites

Anchoring noble metal sites through photo-reduction is an effective way to modulate charge distribution on photocatalytic interfaces, thereby enhancing photocatalytic performance. The irradiation field on the exposed surfaces of photocatalysts has an important influence on the morphology and distribution of noble metal sites. However, non-uniform light field derived from the scattering effects of particle-form photocatalysts hinders the well-distributed photo-deposition of noble metal sites. To address this challenge, we proposed a photo-deposition method utilizing the optical fiber coated with photocatalysts. TiO2 nanorod (NR) array was coated on the optical fiber to achieve a well-distributed irradiation filed across the NR array. This resulted in a concentration of the irradiation field primarily within the NR array, maintaining uniformly distributed light intensities throughout. Palladium (Pd) sites dominated by nanoclusters were well distributed on TiO2 NR array utilizing a photo-reduction method. These Pd sites functioned as electron acceptors, facilitating the effective separation and transfer of photo-generated carriers. Consequently, an highly active photocatalytic reaction interface was constructed, demonstrating the accumulation of a substantial concentration of holes and their efficient conversion into hydroxyl radicals (·OH). Notably, hydroxyl radicals with a concentration of 62.6 μM could be generated within 14.4 min. The construction of this efficient photocatalytic interface offers an optimal platform for accelerating photocatalytic reactions and enhancing photocatalytic efficiency.

Optical spectra in pure-silica-core single mode optical fibers after high-fluence reactor irradiation

The paper describes the study of radiation-induced attenuation (RIA) spectra in reactor-irradiated single mode optical fibers (OFs) with differente high-temperature coatings (polyimyde, aluminum and copper). The OFs were previously irradiated up to fast neutron fluence 1.8·1020 n/cm2 and gamma dose 2.32 GGy. After three years of annealing at room temperature (RT), the RIA spectra were examined within the range of 650–1700 nm. All RIA mechanisms acting within this spectral range were identified: absorption bands attributed to non-bridging oxygen hole centers, a long-wavelength (LW) band with a maximum at λ > 1800 nm, and unsaturated “grey” loss due to coating microbendings or damage. It was found out that RIA asocciated with the LW band can be significantly annealed at room temperature in polyimide-coated OFs. RIA mechanisms influenced by the coating were found to be more stable than those causing LW-RIA.The LW-RIA arising during reactor and gamma irradiation exhibits a similar shape, approximated by the Kubo-Greenwood formula for alternative conductivity, which describes the absorption of self-trapped holes (STH) and exibits close thermal stability at RT. This suggests a STH-like nature of LW-RIA. The accurate approximation of the RIA spectrum in the near-infrared range requires considering contributions of the unsaturated loss or contributions of an absorption band peaking at an energy of 1.33 eV with a half-width of 0.45 eV.

Laser-Induced Graphene-Based Fabry-Pérot Cavity Label-Free Immunosensors for the Quantification of Cortisol

There is a strong and growing need to monitor stress biomarkers in human beings and animals for real-time wellness assessment, which is a key indicator of health. Toward this, we report an optical fiber immunosensor based on laser-induced graphene (LIG) for the potential quantification and monitoring of cortisol hormone. The developed sensors were created using the Fabry-Pérot cavity principle. The cavities were filled with polyimide (PI) and, in some cases, PI mixed with gold nanoparticles. The interferometers were tested for temperature and refractive index, and an increase of two times in the sensitivity to the refractive index was observed due to the addition of the gold nanoparticles. In addition, the PI cavity was partially transformed into LIG using a CO2 20 kHz pulsed laser. The resulting LIG morphology was quite porous and presented a leafy texture. The presence of LIG creates a second cavity within the interferometer, and as a consequence, the spectral response of the interferometers resembled the Vernier effect. The refractive index behavior of the LIG-modified interferometers shows improvements in sensitivity up to 15.3 times due to the creation of the LIG cavity. The interferometers were then functionalized with anti-cortisol to promote an affinity for cortisol. Excellent sensitivities of up to -34.7±0.7 nm/log(ng/mL) were achieved within few ng/mL concentration ranges (within the 0.5 to 3 ng/mL). The results obtained show an increase of up to 50 times in sensitivity when compared with other cortisol sensors. The achieved limit of detection was 0.1 ng/mL for the proposed sensors. The sensors’ responses were also shown to be immune to the interference from substances such as glucose, sucrose, fructose, and ascorbic acid. This study lays the foundation for new cortisol biosensors demonstrating a great potential for detection in a simple and highly sensitive way, opening its path for relevant biomedical and environmental monitoring applications in real samples. As a future outline, selectivity studies employing the detection of cortisol in the presence of interfering agents, both using synthetic and real samples, will be accomplished in order to fully investigate the potential of these sensing tools in real-life scenarios.

Underground Cable Fault Detection Using IOT

Abstract: The objective of this project is to determine the distance of underground cable fault from base station in kilo meters using an Arduino. The underground cable system is a common practice followed in many urban areas. An issue may happen in an underground cable just because of earth tremors or any burrowing procedure. Since the area of the issue happened is obscure it is very hard for the fixing procedure. This hindrance is handled with the assistance of optical fibre framework. A lot of optical strands is put alongside the force cables. While a fault occurs for some reason, at that time the repairing process related to that particular cable is difficult due to not knowing the exact location of the cable fault. The proposed system is to find the exact location of the fault. The project uses the standard concept of Ohms law i.e., when a low DC voltage is applied at the feeder end through a series resistor (Cable lines), then current would vary depending upon the location of fault in the cable. In case there is a short circuit (Line to Ground), the voltage across series resistors changes accordingly, which is then fed to inbuilt ADC of Arduino to develop precise digital data for display in kilometres. The project is assembled with a set of resistors representing the cable length in km and the fault creation is made by a set of switches at every known km to cross check the accuracy of the same. The fault occurring at a particular distance, the respective phase along with the distance is displayed on the LCD. The same information is also sent over IOT, interfaced to the Arduino. Further this project can be enhanced by using capacitor in an ac circuit to measure the impedance which can even locate the open circuited cable, unlike the short circuited fault only using resistors in DC circuit as followed in the above proposed project.

Optical routing: link failure detection-aided optimal routing in elastic optical networks using hybrid deep learning with target-based feature pool formation

ABSTRACT The Elastic Optical Network (EON) is a kind of optical network where a large amount of data signals are given into the channel of optical fibre by modulating with the optical signal. One of the most crucial tasks for optical networks is resource allocation and routing, which has a significant impact on resource effectiveness and network capacity. Deep learning-based routing and resource allocation have piqued the interest of researchers to a considerable extent. Thus, this paper aims to develop efficient link failure detection in EONs with hybrid deep learning strategies. Initially, the data aggregation is performed to combine the multiple link information from EONs. The aggregated link data is given into the hybrid detection model named as Enhanced Deep Learning Network (EDLNet), where the One-Dimensional Convolutional Neural Network (1D-CNN) is used for extracting the features and used for generating the target-based feature pool. This feature pool is utilised in the Long Short-Term Memory (LSTM) network for detecting link failures. The parameter optimization is done by the hybrid 1DCNN-LSTM network with the support of the Hybrid Red Deer with Sewing Training-based Optimisation (HRD-STO) to achieve accurate detection results. The detected failed link is mitigated at the time of routing, and only reliable links are used to attain certain objective constraints. These objective constraints include shortest path, link reliability and stability, throughput and delay for enhancing the efficiency of the EONs. The replication analysis reveals the effectiveness of the proposed link failure detection model by comparing it with the conventional models.

Beam loss detection based on generation of Cherenkov light in optical fibers in the CERN Linear Electron Accelerator for Research

Cherenkov optical beam loss monitors (oBLMs) based on optical fibers are a revolutionary achievement among the monitoring systems in particle accelerators. Due to the nature of the Cherenkov phenomenon and the intrinsic characteristics of optical fibers, the photon production and fiber light transmission need to be studied to deduce the total amount of Cherenkov photons detected by the photosensors attached at the end of the system. Simulations of the Cherenkov oBLM detector system have been implemented using the software with postprocessing considering the light attenuation and capture factors in the optical fiber. In addition, the study includes the longitudinal beam loss localization of the controlled beam losses produced along the CERN Linear Electron Accelerator for Research (CLEAR) test facility line. In this paper, the Cherenkov photon detection by an oBLM installed in the CLEAR facility is simulated, analyzed, and compared with experimental data. Published by the American Physical Society 2024

Dynamics of switching optical soliton in fiber with sixth order dispersion and inter modal dispersion

This work pertains to the study of switching soliton in fiber for nonlinear Schrödinger (NLS) equation with the presence of higher order dispersion and inter modal dispersion (IMD). The nonlinear wave in the optical fiber are described by the NLS equation which having the second order, fourth order, fifth order, sixth order dispersion, higher order nonlinearity and IMD. The main goal of the paper is to examine the sixth order dispersion on nonlinear wave in the fiber with the conditions of IMD. Hence, we employ the Bäcklund transformation of the Riccati equation (BTRE) approach to NLS equation and obtain the soliton solution. By the use of soliton solution along with graphical snapshots, we provide the conditions for forming switching solition in optical fiber and also analyze the effect of sixth order dispersion in fiber. The stability of the solution of NLS equation is also addressed.

Stochastic wave solutions of fractional Radhakrishnan–Kundu–Lakshmanan equation arising in optical fibers with their sensitivity analysis

Stochastic wave solutions of fractional Radhakrishnan–Kundu–Lakshmanan equation arising in optical fibers with their sensitivity analysis

Numerical simulations and analytical approach for three-component coupled NLS-type equations in fiber optics

Numerical simulations and analytical approach for three-component coupled NLS-type equations in fiber optics

Korean Paradox of Public Support for the Research and Development Investment in the Sustainable Performance of the Regional Economy

The Swedish Paradox is a well-known phenomenon related to high research and development (R&D) investment with supposedly low aggregate economic performance owing to economic saturation. The Korean economy has not yet become an advanced economy; however, its R&D performance is negligible. Recently, also the R&D share of the GNP has become much higher, and its contribution to the economic growth rate is rapidly decreasing, implying a negative relationship between R&D activities and economic performance. This study uses slacks-based data envelopment analysis to investigate investment performance at the local government level in Korea. Our findings reveal that the average score for R&D investment performance in Korea is 64%, indicating huge potential for an efficiency enhancement of 36%. Notably, among the 16 local governments examined, Seoul and its surrounding metropolitan areas showed the lowest R&D efficiency, while Gangwon and Gwangju exhibited superior performance. Since these two regions have promoted specific missions, such as the medical hub in Gangwon and the optical fiber strategic platform in Gwangju, precise and accurate differentiation appears necessary to avoid a lack of governance. To determine the workable mechanism of R&D support policies, we further divided R&D productivity into three categories by incorporating the Malmquist Index (MI). The paper productivity of R&D shows an increasing trend over the experimental period from 2016 to 2021. However, overall, the MI shows slightly deteriorating productivity with 0.978, owing to the aggravating effect of patents and commercialization of R&D. The success in the paper comes from the harmonized partnership between the strong push factor of the government and voluntary pull factor of the R&D support receiving universities. Thus, we suggest that the Korean government should not depend on the superficial effectiveness of R&D in the term but on public–private partnerships with stronger performance-oriented responsibility.

Design and simulation implementation of bismuth-doped fiber laser

Rare-earth doped fibers are an important means of expanding the wavelength band of optical fibers. Currently, researchers aim to broaden the working wavelength band of optical fibers by doping with different rare-earth elements, thereby increasing the amount of information that can be transmitted. In this paper, a bismuth-doped fiber laser operating around 1300nm was designed. A basic physical model for implementing a bismuth-doped fiber laser was proposed based on the energy levels and transition processes of bismuth, rate, and power propagation equations. It was possible to determine the link between pump power and laser power at a wavelength of 1300 nm by modeling tests using the physical model. Additionally, the relationship between pump light and laser power in bismuth-doped fiber at different positions and propagation directions was analyzed. Suggestions for the future large-scale application of bismuth-doped fiber lasers around the 1300nm wavelength band were provided.

Exploring the Depths: Soliton Solutions, Chaotic Analysis, and Sensitivity Analysis in Nonlinear Optical Fibers

Exploring the Depths: Soliton Solutions, Chaotic Analysis, and Sensitivity Analysis in Nonlinear Optical Fibers

Carbon Dot Synthesis in CYTOP Optical Fiber Using IR Femtosecond Laser Direct Writing and Its Luminescence Properties

Carbon Dot Synthesis in CYTOP Optical Fiber Using IR Femtosecond Laser Direct Writing and Its Luminescence Properties

Plastic optical fibers as optical illuminators for digital holography and structured fringe patterns generation

Plastic optical fibers as optical illuminators for digital holography and structured fringe patterns generation

Gap solitons in optical fibers with the concatenation model

AbstractThis paper recovers gap solitons from Bragg gratings of the concatenation model. The new mapping method recovers a full spectrum of optical solitons. The parameter constraints for the existence of such solitons are enumerated.

Current Trends in Liquid Crystal Polymers and Their Applications: A Review

Liquid crystal polymers (LCPs) are now highly focused by researchers due to their improved thermal properties, mechanical strength, excellent dielectric strength, resistance to solvents, better dimensional stability, and gas barrier properties. LCPs can be used in valuable widespread applications such as energy storage, high-performance polymer fibers, actuators, information technologies, surface modification, shape memory materials, data storage, fiber optics, the medical field, electrical or electronics devices, aircraft, chemical, domestic equipment, ultra-high-strength fibers, biosensing, advanced communication systems, satellite systems, biosensing, bio-oscillators, and bioprocess monitoring. LCPs can self-assemble into different liquid crystalline phases like nematic, cholesteric, smectic, and columnar phases. The self-assembling structures of LCPs can be affected by the chemical and structural structures of the backbone of the polymeric material, nearby alkyl tails, mesogenic units, flexible spacers, etc. Depending on the mesogenic units in their molecular architecture, LCPs are basically classified into various categories, such as crosslinked, main chain, and sidechain. Again, they are also classified as cholesteric, nematic, and smectic mesophases. This paper provides a fundamental understanding, an informative overview, and details of structural aspects, properties, classification, commercial aspects, and applications of LCPs.

Novel transient-state analysis approach for distributed temperature sensing based on spontaneous Raman scattering

The light scattering phenomenon in optical fibres has been implemented in several applications for years. Nowadays, commercial distributed sensing systems for temperature measurements – distributed temperature sensing (DTS) – are gaining more attention and are being applied in many fields. The DTS systems are commonly based on optical time domain reflectometry or optical frequency domain reflectometry analysis approaches. This paper presents the simulation model and primary experimental results of a novel approach for data analysis for DTS systems based on the measurement of the backscattered Raman anti-Stokes radiation: the optical transient-state domain reflectometry. The novelty of this approach is the fast and accurate proposed analysis algorithm, as well as the cost-effective, secure and reliable set-up, whose main aspect is the implementation of long, low-power input laser pulses.

Localization of Dual Partial Discharge in Transformer Windings Using Fabry–Pérot Optical Fiber Sensor Array

The power transformer is one of the most critical core devices for energy exchange in power systems, and its safe and stable operation is directly related to the reliability of the power grid. Partial discharge is the main cause of insulation degradation and failure of high-voltage electrical equipment. Online monitoring and accurate localization of partial discharge can provide information on the aging of power equipment, which is of great value for improving the safe operation and maintenance of the power grid. Internal dual partial discharge in transformer windings is a more complex type of fault. Since it is located inside the windings, the signal is attenuated and distorted, making it difficult for traditional monitoring methods to capture such partial discharge signal The Fabry–Perot optical fiber sensor is an ultrasonic detection method that can be built into the transformer interior. This sensor has high sensitivity and a small size, enabling flexible placement at different locations inside the transformer for precise partial discharge detection. Especially for the narrow space inside the high and low voltage windings, F–P sensors can form an array, utilizing the array’s directivity to locate the fault points. In this study, an ultrasonic detection system based on the F–P optical fiber sensor array was developed. The system utilizes a directional cross-localization algorithm based on the multiple signal classification (MUSIC) algorithm to accurately locate dual partial discharge sources. This partial discharge detection system was applied to a 35 kV single-phase transformer, enabling the localization of dual partial discharge sources within the high and low voltage windings. Combined with experimental results, this method exhibits high localization accuracy and is particularly suitable for detecting partial discharge phenomena that occur within or between transformer windings.

Time-domain Vernier effect-based optical fiber sensor

In this Letter, we demonstrate an easy-to-fabricate time-domain Vernier-effect-based sensor. An all-fiber variable optical delay line (VODL) is utilized to drive an OPD scan of two interferometers simultaneously, and fiber Bragg gratings are used to filter out two slightly detuned time-domain interferometric signals. Then two normalized interferograms with different spatial frequencies can be achieved and utilized to generate an envelope modulation, viz., a Vernier envelope, with enhanced sensitivity in comparison to the native state of the interferometers used. The sensitivity magnification factor of our structure can be regulated simply via altering the resonant wavelength difference of FBGs rather than optimizing the OPDs of the interferometers. The proposed sensor is independent of the precise and complicated fabrication procedures. The Vernier signal can be demodulated without a broadband light source and spectrometer. We argue that the proposed structure may inspire a new concept for constructing simple and cheap Vernier effect-based sensors that are well suited for practical applications.

Spatial and mode selective switch for orbital angular momentum mode division multiplexing

In analogy to a wavelength selective switch in wavelength-division multiplexing (WDM) optical fiber communication systems, a spatial and optical mode selective switch (SMSS) would be an important component in future ultrahigh capacity optical fiber communication systems based on space and mode division multiplexing. In this work, a free-space SMSS for orbital angular momentum (OAM) mode-division multiplexing (MDM) is proposed and experimentally demonstrated. The SMSS consists of a separating part for transforming OAM modes to spatial modes and a recombining part for selecting and recombining the modes to any spatial channel. The SMSS is able to implement strictly non-blocking switching between a total of 36 SDM/MDM channels configured as four spatial channels each supporting nine OAM mode channels.