Optical Fiber Research Articles

Overview of the Infrared Radiation Responses of Telecom-Grade Single Mode Optical Fibers

Overview of the Infrared Radiation Responses of Telecom-Grade Single Mode Optical Fibers

First spectroscopic study of HFRC plasma

An advanced spectral diagnostic system was developed to measure the electron temperature (T e), electron density (N e), and ion temperature (T i) of the Huazhong University of Science and Technology field-reversed configuration plasma. The system consists of an optic fiber spectrometer with a wide spectral band and a 670 mm focal length high throughout Czerny–Turner monochromator equipped with both a 3600 g mm−1 grating and a 2400 g mm−1 grating to measure the line spectrum. Accompanying these components is an electron-multiplying charge-coupled device camera to capture spectral data. The relative intensity of the optical fiber spectrometer was calibrated using a standard luminance source, and the wavelength calibration of the spectrometer was accomplished using a Hg/Ar lamp. This diagnostic setup was configured to measure electron density based on the Stark effect of Hγ (n = 5 → n = 2; 434.04 nm). Doppler broadening of an O III (2s22p(2P0)3p → 2s22p(2P0)3s; 375.988 nm) emission line was measured and analyzed to obtain the ion temperature, and electron temperatures were estimated from the relative strength of Hβ (n = 4 → n = 2; 486.14 nm) (Dβ) and Hγ (Dγ) spectral lines when the electron density was obtained from Stark effect measurements. The initial experimental results indicate that the highest electron temperature of the formation region was approximately 8 eV, the electron density of the colliding-and-merging region was approaching 1020 m−3, and the ion temperature reached about 40 eV.

Theoretical Investigation on the Effective Coupling Optical System between Astigmatic Tapered Diode Laser Beam and Single-Mode Optical Fibers

Theoretical Investigation on the Effective Coupling Optical System between Astigmatic Tapered Diode Laser Beam and Single-Mode Optical Fibers

Experimental system and method of aerobic thermal environment simulation based on laser heating

Considering the superior luminous intensity characteristics of lasers, a thermal simulation platform employing laser-induced heating in an aerobic environment was developed. Achieving a uniformly distributed flat-topped square laser beam output was facilitated through optical fibre bundling techniques, while precise control over laser power output was attained through current modulation. Utilising the aforementioned system, thermal shock simulation experiments were conducted in an aerobic environment, subjecting two types of high-temperature-resistant composites, namely C/C and C/SiC, to temperatures up to 1800 °C. These composites were lightweight, heat-resistant materials designed for hypersonic vehicle applications. The results show that the system and method can be used to simulate high temperatures, rapid temperature increases, and thermal shocks on C/C composite materials, with minimal variation in the coupling coefficient under aerobic conditions. The system and method can also provide key technology support for thermal-force-oxygen coupling testing of high temperature resistant materials.

PUDCN: two-dimensional phase unwrapping with a deformable convolutional network

Two-dimensional phase unwrapping is a fundamental yet vital task in optical imaging and measurement. In this paper, what we believe to be a novel deep learning framework PUDCN is proposed for 2D phase unwrapping. We introduce the deformable convolution technique in the PUDCN and design two deformable convolution-related plugins for dynamic feature extraction. In addition, PUDCN adopts a coarse-to-fine strategy that unwraps the phase in the first stage and then refines the unwrapped phase in the second stage to obtain an accurate result. The experiments show that our PUDCN performs better than the existing state-of-the-art. Furthermore, we apply PUDCN to unwrap the phase of optical fibers in optical interferometry, demonstrating its generalization ability.

Triple-Channel Optical Fiber Surface Plasmon Resonance Sensor for Simultaneous Detection of Relative Humidity, Magnetic Field, and Temperature

Triple-Channel Optical Fiber Surface Plasmon Resonance Sensor for Simultaneous Detection of Relative Humidity, Magnetic Field, and Temperature

Identification of Corrosion-Induced Optical Fiber Acoustic Emission Sensor Signals on the Bottom Plate of Oil Storage Tank Based on Multichannel Attention Mechanism (CBAM)

Identification of Corrosion-Induced Optical Fiber Acoustic Emission Sensor Signals on the Bottom Plate of Oil Storage Tank Based on Multichannel Attention Mechanism (CBAM)

Perspectives on endoscopic functional photoacoustic microscopy.

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

Distributed Partial Discharge Acoustic Signal Detection and Localization Technology for GIL With Built-in Fiber Optics

Distributed Partial Discharge Acoustic Signal Detection and Localization Technology for GIL With Built-in Fiber Optics

A novel refractive index based-fiber optic sensor for milk adulteration detection

Milk adulteration poses a significant risk to public health and consumer trust, compromising its nutritional value. To address this, we've developed an optical fiber-based sensor using a Lossy Mode Resonance (LMR) approach. Antimony Oxide (Sb2O3) serves as the sensing layer, deposited onto the optical fiber's unclad core using Radio Frequency Magnetron sputtering. The sensing layer underwent comprehensive characterization, including X-Ray diffraction (XRD), UV–Vis spectroscopy, Ellipsometer, Atomic Force Microscopy (AFM), EDAX, and Field Emission Scanning Microscopy (FESEM). The sensor was tested for formaldehyde and water adulteration across normal milk type 1, full-fat milk type 2, vendor milk type 3, and, with concentrations ranging from 0 % to 10 %. Observations included resonance wavelength shifts and sensing parameters such as sensor response, sensitivity, and repeatability. For Sb2O3-coated sensor probes, responses to formaldehyde and water adulteration for type 1 milk is 2.05 % and 2.22 %, type 2 milk is 2.17 % and 2.4 %, and type 3 milk is 1.90 % and 1.95 %. Sensitivity for Sb2O3-coated probe to formaldehyde are 2.2 nm/v% (type 1 milk),1.9 nm/v% (type 2 milk) and 1.5 nm/v% (type 3 milk). For water in milk, the sensitivities are 1.7 nm/v%, 1.5 nm/v%, and 1.2 nm/v%. Furthermore, a prototype sensor probe has been developed for continuous milk adulteration monitoring, interfaced with Arduino and Thing Speak.

A cascade SPR sensor based on Ag/Au coated coreless optical fiber for RI and pH measurement

Due to the restriction of resonant wavelength, the detection range of traditional two-parameter sensors is greatly limited. To solve this problem, a cascade SPR sensor with Ag/Au coating is proposed to measure refractive index (RI) and pH value. In this paper, coreless optical fiber is used as the sensor probe, and Ag/Au are coated on its surface by a magnetron sputtering method. The two sensing channels of this cascade sensor are independent of each other and have a wide parameter detection range. The effects of sensor length and coating time on the performance of the sensor were investigated, and the optimal sensor length and coating time were determined. The experimental results show that the maximum refractive index sensitivity is 3888.6 nm /RIU in the RI range of 1.333–1.385, and the maximum pH sensitivity is 38.01 nm/pH in the pH range of 3.15–8.86. The sensor has the advantages of strong stability and high integration and has a good application prospect in the fields of biosensing and environmental detection.

Application of Long-Period Fiber Grating Sensors in Structural Health Monitoring: A Review

Structural health monitoring (SHM) is crucial for preventing and detecting corrosion, leaks, and other risks in reinforced concrete (RC) structures, ensuring environmental safety and structural integrity. Optical fiber sensors (OFS), particularly long-period fiber gratings (LPFG), have emerged as a promising method for SHM. Various LPFG sensors have been widely used in SHM due to their high sensitivity, durability, immunity to electromagnetic interference (EMI) and compact size. This review explores recent advancements in LPFG sensors and offers insights into their potential applications in SHM.

Multi-Core Fiber Bragg Grating and Its Sensing Application.

With the increase in the demand for large-capacity optical communication capacity, multi-core optical fiber (MCF) communication technology has developed, and both the types of MCFs and related devices have become increasingly mature. The application of MCFs in the field of sensing has also received more and more attention, among which MCF fiber Bragg grating (FBG) devices have received more and more attention and have been widely used in various fields. In this paper, the main writing methods of MCF FBGs and their sensing applications are reviewed. The future development of the MCF FBG is also prospected.

A novel flexible optical fiber magnetic field sensor based on integrated Fe3O4 nanoparticles

We propose a new flexible optical fiber magnetic field sensor (FOMS) based on the combination of Michelson interferometer and the PDMS polymer-based optical fiber. The flexible optical fiber magnetic field sensor is made of stretchable elastomer. It uses a stepped refractive index core-cladding structure to achieve effective light confinement, thus enabling stable transmission of light in the waveguide. When the magnitude of the external magnetic field is changed, the micro bending of the sensing region of the optical fiber causes its equivalent refractive index to change, which leads to a drift in the interference spectrum. It is shown that the magnetic field sensitivity of this optical fiber magnetic field sensor reaches −62.8 pm/mT for wavelength detection in the measurement range of 0–200 mT. The FOMS has the characteristics of high sensitivity, good linearity, good temperature response capability, sensitive response, and resistance to electromagnetic interference. In the future, the sensor will have a broad application prospect in medical, geography, aerospace and other fields.

Novel mining conveyor monitoring system based on quasi-distributed optical fiber accelerometer array and self-supervised learning

Belt conveyors in mining are crucial, with downtime leading to significant losses and safety hazards. Unplanned shutdowns often result from idler failures. To address this, an online monitoring system for continuous idler health assessment is proposed. Considering the large number and dense spatial distribution of idlers over long distances, this work presents a system that utilizes a quasi-distributed optical fiber accelerometer array. This array incorporates phase-sensitive optical time domain reflectometry (Phase-OTDR) interrogation technology and ultra-weak fiber Bragg gratings (UWFBGs) to effectively capture idler vibrations. The designed array achieves high-sensitivity vibration sensing with a sensitivity of 2.4 rad/g and a resolution of 1.7 mg/Hz. After collecting the vibrations of idlers by the designed accelerometer array, an automatic fault classification algorithm based on self-supervised learning (SSL) is introduced, which requires only a small number of labeled samples. By leveraging large amount of unlabeled data in the pretext task, the algorithm efficiently extracts latent features from the quasi-distributed accelerometer array. A diagnosis accuracy of 95.37 % can be achieved on a seven-class classification task with only 3.6 % labeled data (16 samples/class). This system offers a promising solution for idler monitoring, combining high sensitivity, distributed measurement capabilities, enhanced security, and superior fault detection accuracy.

Optical signals measurement of discharge plasma in air switch cabinet using a fluorescent optical fiber as the sensor

Air switch cabinets are widely employed in the power industry, there is, however, no reliable methods for detecting partial discharges (PDs). Because fiber optic-based sensors are easy to install and have anti-electromagnetic interference capabilities, they are well suited for PDs detection in switch cabinets with their many components and metal shell structure. In this work, corona discharge in an air switch cabinet was detected using fluorescent fiber, and the characteristics of PDs were analyzed. Furthermore, experimental investigations were conducted to explore the impact of gas pressure and fiber length on the PDs detection. The results exhibit a correlation between the aforementioned factors and the PDs’ total amplitude, maximum amplitude, number of pulses and detection limit of PD quantity. The results can provide references for the application of fluorescent optical fiber on the PD detection in air switch cabinet.

Optical fiber LSPR sensor for SARS-CoV-2 N gene detection based on AuNRs

A novel SARS-CoV-2 N gene optical fiber biosensor based on ASO-coated gold nanorods is proposed in this work. A fiber probe prepared by AuNRs self-assembly was used to detect N gene by complementary base pairing method. The detected material was processed into AuNRs-ASO2-N gene coupler by cross-linking, and the pairing of N gene with ASO1 connected to AuNRs on the surface of the optical fiber formed the hydrogen bonding. The coupling of AuNRs resulted in a left shift of the peak position and a decrease in absorbance in the LSPR spectrum. In this manuscript, it is verified for the first time by simulation and experimental characterization that the coupling mode of AuNRs on the surface of the optical fiber is side by side, which leads to a left shift of the peak position of the LSPR absorption peak on the optical fiber. It is also proved that sandwich method is superior to the traditional method of changing the refractive index. The response time of the sensor is 10 min, and the detection limit is 1 pM, and the results show that the optical fiber sensor based on ASO-coated AuNRs has excellent RNA detection performance in artificial body fluids and is very suitable for RNA detection.

Recent Advances in Fabrication and Applications of Yttrium Aluminum Garnet-Based Optical Fiber: A Review.

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.

Optical soliton solution of the perturbed Biswas-Milovic equation having cubic-quintic-septic law nonlinearity in the presence of spatio-temporal and chromatic dispersion

In this manuscript, we investigate the analytical and soliton solutions of the cubic-quintic-septic law for the perturbed Biswas-Milovic equation, considering spatio-temporal and chromatic dispersions. The perturbed Biswas-Milovic equation with the spatio-temporal and chromatic dispersion terms provides a comprehensive study for describing nonlinear optical wave propagation in optical fiber. We use the wave transformation to reduce the main equation to a nonlinear ordinary differential equation. The transformation of the original equation into a more simplified form aims to attain a more profound comprehension of the fundamental dynamics of the system. We retrieve the analytical solutions of the presented model by implementing the new Kudryashov technique and a subversion of the new extended auxiliary equation approach. Besides, bright, singular, and V-shape soliton structures are represented. By employing powerful analytical techniques, we systematically derive a wide range of soliton solutions. This approach successfully captures diverse soliton types highlighting the novelty of applying the new Kudryashov technique and a subversion of the new extended auxiliary equation method to this complex model. Moreover, we analyze the soliton behavior influenced by various parameters. The analysis of the parameter influences reveals the complicated relationship governing the dynamics of the perturbed Biswas-Milovic model. Furthermore, this manuscript includes the modulation instability analysis for the presented model. Conducting modulation instability analysis for the presented equation enhances our understanding of the system’s stability and dynamics.

Optical Fibers Functionalized with Single-Walled Carbon Nanotubes for Flexible Fluorescent Catecholamine Detection.

Despite the blockbuster popularity of drugs that act on catecholamine receptors, catecholamine dynamics in human health and disease remain an incomplete picture. Recent advances in fluorescent sensors have enabled unprecedented access to catecholamine dynamics in preclinical animal models, but the requirements of these technologies limit translational value for clinical diagnostics. Here, we present a flexible and convenient tool for fluorescent catecholamine detection by functionalizing optical fibers with single-walled carbon nanotube (SWNT)-based near-infrared catecholamine sensors (nIRCats), a form factor that has potential for more convenient and less invasive clinical translation. We show that these near-infrared functionalized (nIRF) fibers respond to dopamine in a biologically-relevant concentration range (10nM through 1 μM) with a mean ΔF/F0 of 0.022 through 0.411, with no statistically significant effect on signal magnitude after 16-hour exposure to human blood plasma. We further demonstrate the utility of these fibers in as little as 10 μL volumes of clinically relevant biofluids up to 24 weeks after preparation, with a ΔF/F0 of up to 0.059 through 1.127 for 10 nM through 1 μM dopamine. We also introduce a compact, mobile dual-near-infrared fiber photometry rig and demonstrate its success detecting dopamine with 0.005 ΔF/F0 in acute brain slices with nIRF fibers. Together, this fiber-based tool and photometry rig expand the toolbox of catecholamine detection technologies to a broader range of applications.