Optical Fiber Research Articles

HMS optical fiber gas sensor based on double-layer WO3@CQDs porous film modified cladding for detecting 2-butanone gas at room temperature

In this study, a hollow malposition structure (HMS) optical fiber 2-butanone gas sensor based on double-layer WO3@CQDs porous film is proposed, and realizes the ppb detection of 2-butanone gas at room temperature. The HMS can excite the evanescent field and sense the gas adsorption on the fiber surface. The experimental results show sensitivity of 3.09 pm/ppm for this HMS optical fiber gas sensor based on double-layered WO3@CQDs porous film, which is 6.05 times higher than that of the sensor coated with single-layer WO3@CQDs porous film. In addition, a limit of detection (LOD) reaches 500 ppb. The response time is 11.7 s and the recovery time is 5.72 s. Density functional theory (DFT) results show that the modification of CQDs improves the adsorption capacity of WO3@CQDs for 2-butanone gas molecules and changes the refractive index of the material. The sensor has the advantages of small volume, high sensitivity and a low LOD, which is of great significance for the detection of trace 2-butanone gas.

Dynamics of optical solitons and sensitivity analysis in fiber optics

The nonlinear Schrödinger equation (NLSE) and its various forms have significant applications in the field of soliton theory. The Fokas-Lenells (FL) equation stands as a cornerstone in deepening our understanding of nonlinear wave dynamics within optical systems, particularly concerning the behavior of ultrashort pulses across different media. Its significance lies in providing a comprehensive framework to study and analyze complex phenomena, ultimately contributing to advancements in optical technology and applications. The FL equation is an integrable extension of the NLSE that provides a description of the nonlinear propagation of pulses in optical fiber. This paper seeks to discover optical soliton solutions for the FL equation by employing a modified sub-equation method. Additionally, the sensitivity analysis is described by using the various initial conditions. The main novelty of this paper lies in conducting a sensitivity analysis of the FL equation by examining the effects of various initial conditions, providing deeper insights into how these conditions influence the behavior of soliton solutions. For the physical behavior of the models, some solutions are graphically shown in 2D, 3D, and contour graphs by assigning specific values to the parameters under the provided situation at each solution. As a result, we discovered several new families of exact traveling wave solutions, such as bright solitons, dark solitons, and combined bright and dark solitons. This research opens numerous avenues for further exploration in the field of nonlinear wave dynamics and optical soliton theory. The discovery of exact soliton solutions for the FL equation through a modified sub-equation method paves the way for deeper investigations for newcomer researchers. The results of this study will contribute further to the field of mathematical physics, particularly in enhancing the understanding of nonlinear wave propagation and soliton theory in optical and other physical systems.

Light-emitting diode-based absorbance detectors for flow-through analysis in analytical chemistry: A tutorial

The development of light-emitting diodes (LEDs) has played a significant role supporting many recent advances made in chemical analysis. Their small size, low power consumption, and semi-monochromaticity make them ideal light sources for portable photometric devices used in field and on-site analysis, environmental monitoring, and industrial applications, such as process analytical technology (PAT) and continuous real-time analysis. This tutorial provides an overview and critical comparison of the key components in LED-based absorbance detectors, including light sources, optical fibres, flow cells, and photodetectors. Fundamental aspects of LEDs relating to their use in such simple detectors are discussed in detail, along with the development of multi-wavelength detectors that incorporate multiple LEDs. The tutorial also details the different methodologies for assessing and characterising the LED-based absorbance detectors. Finally, this tutorial presents some selected applications of LED based photometric detectors in gas sensing, flow injection analysis (FIA), and coupled with separation techniques such as ion chromatography, liquid chromatography, and capillary zone electrophoresis (CZE).

Double-pole anti-dark solitons for a Lakshmanan-Porsezian-Daniel equation in an optical fiber or a ferromagnetic spin chain

Under investigated in this paper is a Lakshmanan-Porsezian-Daniel equation that describes the nonlinear spin excitations in a (1+1)-dimensional isotropic biquadratic Heisenberg ferromagnetic spin chain with the octupole-dipole interaction or the propagation of the ultrashort pulses in a long-distance and high-speed optical fiber transmission system. Under certain parameter conditions, we simultaneously take the multi-pole phenomena and breather-to-soliton transitions into account, then utilize the second-order generalized Darboux transformation to derive the double-pole anti-dark solitons and graphically illustrate them. Asymptotic analysis is conducted to examine the interaction properties of double-pole anti-dark solitons, including their characteristic lines, amplitudes, phase shifts, slopes and position differences. Unlike the double-pole anti-dark solitons found in the Hirota equation, the ones in this study exhibit a distinct feature: Different soliton components share the same amplitude.

Coupled Nonlinear Schrödinger Equations for Pulse Interactions in Optical Fibers: Self- and Cross-Phase Modulation Effects

Coupled Nonlinear Schrödinger Equations for Pulse Interactions in Optical Fibers: Self- and Cross-Phase Modulation Effects

Evolution characteristics of mining-induced fractures in overburden strata under close-multi coal seams mining based on optical fiber monitoring

Large-scale mining fractures resulting from repeated mining are a major cause of surface water loss in the northern Shaanxi mining area, China. Accurately detecting the evolution of mining-induced fractures is crucial for addressing the fragile ecological environment and ensuring coalmine production safety in this area. This study focuses on the close-multi coal seams mining at the Ningtiaota coalmine, northern Shaanxi, China, investigating the failure types of overburden rock, the evolution of mining-induced fractures, and the height of fracture zones. The results indicate that the failure type of overburden strata transforms from a “trapezoid shape” to an “overlapping trapezoid shape”, with the fracture zone height extending from 64.5 m to 158.5 m due to the superposition of secondary mining. Furthermore, the evolution characteristics of mining-induced fractures shift from a “three-stage and three-step” model to a “three-stage and two-step” model. A characterization model of overburden deformation based on optical fiber sensing is proposed to effectively describe the strain distribution characteristics of overburden failure. This model reveals the spatiotemporal evolution of overburden deformation from the perspective of “horizontal three areas and vertical three zones”, enabling real-time characterization of overburden deformation. The results demonstrate a relative error of less than 5.0 % between optical fiber monitoring and other methods, excluding theoretical calculations. This study offers a technical solution for detecting mining-induced fractures in the northern Shaanxi mining area and holds significant implications for broader studies of overburden deformation and failure under repeated mining.

Use of a rugged mid-infrared spectrometer for in situ process analysis of liquids

The widespread application of mid-infrared (MIR) spectroscopy for process monitoring is currently limited by the poor transmission of MIR light through fibre optics. In this work, the performance of a novel and robust MIR spectrometer has been evaluated for practical deployment in a pilot plant or production environment. The spectrometer utilises a Sagnac interferometer design containing no moving parts and is directly attached to an attenuated total reflectance probe, eliminating the need for fibre optics. The quantitative performance of the spectrometer for the in situ analysis of ternary solvent mixtures was assessed. The predictions obtained by partial least squares were accurate (root mean square error of prediction of < 1% w/w) and comparable to those of a benchmark Michelson-based spectrometer with a fibre-coupled probe, which is more amenable to process development in a laboratory or pilot plant. Calibration transfer between the two spectrometers was performed using the spectral space transformation method to mimic the scenario of the scale-up of a process from the laboratory to pilot scale or from a pilot plant to production scale, where the two different MIR instruments might be deployed. The ability to perform in situ reaction monitoring with the robust Sagnac-based spectrometer was then demonstrated. Spectra acquired during an esterification reaction were resolved using multivariate curve resolution, to produce concentration profiles of each component. These results demonstrate the suitability of this rugged spectrometer for quantitative in situ monitoring of liquid processes, opening up new opportunities for process monitoring in the MIR region.

Introduction to this special section: Fiber optics

Introduction to this special section: Fiber optics

Exploring the nonlinear behavior of solitary wave structure to the integrable Kairat-X equation

This study presented various types of soliton solutions for the nonlinear integrable Kairat-X equation by utilizing the improved F-expansion technique with symbolic computational software Mathematica. Explored results for the nonlinear integrable Kairat-X equation are interesting, novel, and more general with different physical structures of solitary waves and solitons, such as kink wave, mixed dark–bright, peakon, anti-kink wave, bright, anti-kink dark, periodic, and dark solitons. With numerical simulations, the secured soliton solutions visualized in two-dimensional, three-dimensional, and contour graphs represent the physical phenomena of the demonstrated results. The explored soliton solutions will be helpful to comprehend interesting physical structures in fiber optics, nonlinear optics, ferromagnetic dynamics, and many other scientific fields. The extracted soliton structure sheds light that the enhanced technique is effective, powerful, concise, and reliable. We can also investigate the soliton results of other nonlinear integrable partial and fractional equations.

Puck 3D-based modeling and validation of progressive failure in instrumented glass fiber-reinforced polypropylene via the split-disk test

This study analyzes the mechanical behavior and damage progression of filament-wound thermoplastic composite rings, focusing on the effects of embedded fiber optic (FO) sensors. Utilizing a split-disk test, the study evaluates both experimental and numerical approaches to examine the impact of FO sensors in glass fiber-reinforced polypropylene composite rings. The split-disk test is employed to measure key mechanical properties such as hoop tensile strength, stiffness and failure strain using strain gauges and 3D Digital Image Correlation (DIC). The research specifically examines two extreme configurations of FO sensor placement: parallel and perpendicular to the reinforced fibers. The objective is to propose sensor integration that minimizes potential negative effects on the material's properties. Both instrumented and non-instrumented samples are analyzed numerically and experimentally. The experimental phase involves detailed mechanical characterization using the split-disk test, while the numerical approach uses a developed UMAT finite element model based on the 3D Puck failure criterion and an element weakening method for progressive failure analysis. The numerical models adopt real microstructural details according to optical microscopic analysis. The study concludes that parallel embedded FO sensors are preferable as they enhance the ultimate strength to failure and avoid creating resin-rich zones near the sensor, thereby improving the overall mechanical performance of the composite rings. The 3D Puck failure criterion combined with the element weakening method provides accurate predictions of fiber failure initiation and growth in the composite rings.

Distributed Backface Strain Sensing of Composite Adhesively Bonded Joints under Mode II Fatigue Loading

When investigating the fracture behaviour of adhesive joints, accurate crack tip localization is under mode II loading is particularly challenging due to the absence of crack opening. The crack front often has a curved shape, so methods that inspect the side of the specimen cannot capture the crack length throughout its width. In this study, distributed backface strain sensing using Optical Backscatter Reflectometry fibre sensors is used to monitor fatigue crack growth in adhesively bonded composite End Notched Flexure Specimens. The obtained backface strain profiles were compared with analytical and Finite Element solutions to understand their relationship with the crack length. Results show that the crack tip position can be found by a local extremum in the first derivative of the strain profile. The proposed monitoring technique was compared with more established techniques for crack length measurement, such as Visual Testing, Compliance Monitoring, and Phased Array Ultrasonic Testing, and was shown to provide good accuracy. The evaluation of these techniques not only plays a crucial role in ensuring accurate testing, but can also contribute to the development of effective strategies for inspection and monitoring of adhesive joints.

Detection of matrix cracks in composite laminates using embedded fiber-optic distributed strain sensing

We used an optical frequency-domain reflectometry fiber Bragg grating (FBG) distributed strain measurement system to detect matrix cracks in carbon fiber-reinforced plastics. Load/unload tests were performed on cross-ply laminates under ambient-, high-, and low-temperature conditions using embedded 100mm gauge FBG sensors. We measured the strain distributed along the gauge and examined the crack initiation using optical microscopy and soft X-ray inspection. A peak appeared in the distributed strain corresponding to the occurrence of cracks. The strain distribution during crack initiation was calculated in each temperature range via finite element analysis and compared with the measurement results. We determined that the number and location of cracks can be determined by extracting the peaks from the distributed strain. However, the peaks in the distributed strain do not correspond to the occurrence of cracks that are close to each other, warranting a measurement method with a higher strain resolution.

Design of a new fiber-optical transmission-based fast ion loss probe on Experimental Advanced Superconducting Tokamak

For the first time, a new probe for fast ion loss has been developed for use in the Experimental Advanced Superconducting Tokamak (EAST) and utilizes optical fiber transmission, the aim of the probe is to study fast ion losses triggered by the ion cyclotron range of frequencies (ICRF) heating and neutral beam injection (NBI) synergy. This probe is used to determine the pitch angle and gyroradii of the ion losses based on the particle positions striking the two-dimensional scintillator. In this paper, the calculation and design of the probe scintillator by using the NLSDETSIM code is discussed. The emitted light from the scintillator is captured by a high-speed camera via an optical lens and high-temperature-resistant fibers and then processed by a signal processing system to determine the real-time energy and angle of the fast ion. Due to the flexible nature of the fiber, the probe is capable of measuring the fast ion losses at various locations within the EAST. Furthermore, the probe can be easily installed by using one of the numerous vacuum feeds on the EAST instead of occupying the entire window. This feature enhances the flexibility of the diagnostic technique.

A Knee-Flexion Angle Optical Fiber Sensor Based on Spherical Fused Triple-Clad Fiber

A Knee-Flexion Angle Optical Fiber Sensor Based on Spherical Fused Triple-Clad Fiber

Highly Sensitive Optical Fiber Dissolved Oxygen Sensor Based on Organic Modified Silicate Porous Matrix by Sol-Gel Method

Highly Sensitive Optical Fiber Dissolved Oxygen Sensor Based on Organic Modified Silicate Porous Matrix by Sol-Gel Method

Low-Concentration Bilirubin Detection Based on Photothermal Effect With Parallel Vernier Effect of Optical Fiber Fabry–Pérot Cavity

Low-Concentration Bilirubin Detection Based on Photothermal Effect With Parallel Vernier Effect of Optical Fiber Fabry–Pérot Cavity

New approach to reduce analysis time of thermal response test: Active thermal response test using linear heat optical fiber sensor

New approach to reduce analysis time of thermal response test: Active thermal response test using linear heat optical fiber sensor

Metropolitan-scale heralded entanglement of solid-state qubits.

A key challenge toward future quantum internet technology is connecting quantum processors at metropolitan scale. Here, we report on heralded entanglement between two independently operated quantum network nodes separated by 10 kilometers. The two nodes hosting diamond spin qubits are linked with a midpoint station via 25 kilometers of deployed optical fiber. We minimize the effects of fiber photon loss by quantum frequency conversion of the qubit-native photons to the telecom L-band and by embedding the link in an extensible phase-stabilized architecture enabling the use of the loss-resilient single-click entangling protocol. By capitalizing on the full heralding capabilities of the network link in combination with real-time feedback logic on the long-lived qubits, we demonstrate the delivery of a predefined entangled state on the nodes irrespective of the heralding detection pattern. Addressing key scaling challenges and being compatible with different qubit systems, our architecture establishes a generic platform for exploring metropolitan-scale quantum networks.

Reconstruction of Nearshore Surface Gravity Wave Heights From Distributed Acoustic Sensing Data

AbstractDistributed Acoustic Sensing (DAS) is a photonics technology converting seafloor telecommunications and optical fiber cables into dense arrays of strain sensors, allowing to monitor various oceanic physical processes. Yet, several applications are hindered by the limited knowledge of the transfer function between geophysical variables and DAS measurements. This study investigates the quantitative relationship between surface gravity DAS‐recorded wave‐generated strain signals along the seafloor and the pressure at a colocated sensor. A remarkable linear correlation is found over various sea conditions allowing us to reliably determine significant wave heights from DAS data. Utilizing linear wave potential theory, we derive an analytical transfer function linking cable deformation and wave kinematic parameters. This transfer function provides a first quantification of the effects related to surface gravity waves and fiber responses. Our results validate DAS's potential for real‐time reconstruction of the surface gravity wave spectrum over extended coastal areas. It also enables the estimation of waves hydraulic parameters at depth without the need from offshore deployments.

AE-IRMamba: Low-Complexity Inverted Residual Mamba for Identification of Piezoelectric Ceramic and Optical Fiber Acoustic Emission Sensors Signals

AE-IRMamba: Low-Complexity Inverted Residual Mamba for Identification of Piezoelectric Ceramic and Optical Fiber Acoustic Emission Sensors Signals