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16 pages, 5165 KiB

Open AccessArticle

In-Plane Strain Measurement in Composite Structures with Fiber Bragg Grating Written in Side-Hole Elliptical Core Optical Fiber

by Karol Wachtarczyk, Paweł Gąsior, Jerzy Kaleta, Alicja Anuszkiewicz, Marcel Bender, Ralf Schledjewski, Paweł Mergo and Tomasz Osuch

Materials 2022, 15(1), 77; https://doi.org/10.3390/ma15010077 - 23 Dec 2021

Cited by 8 | Viewed by 2921

Abstract

In this paper, the application of a fiber Bragg grating written in a highly birefringent side-hole elliptical core optical fiber for two-axial strain measurement is presented. Hybrid optical fiber structures achieved by combining large side-holes and elliptical core result in a very high [...] Read more.

In this paper, the application of a fiber Bragg grating written in a highly birefringent side-hole elliptical core optical fiber for two-axial strain measurement is presented. Hybrid optical fiber structures achieved by combining large side-holes and elliptical core result in a very high birefringence of 1 × 10⁻³ and thus high initial Bragg peak spectral separation of 1.16 nm, as well as a very high transverse force sensitivity, of up to 650 pm/(N/mm) or even −1150 pm/(N/mm), depending on the fiber orientation with respect to the applied force. Due to the ~22 %m/m GeO₂ concentration in the core the fiber being highly photosensitive, which significantly simplifies FBG fabrication by UV illumination without the need for prior hydrogen loading, which worsens thermal stability. Finally, the developed FBGs written in the highly birefringent side-hole elliptical core optical fiber were embedded in the square composite plates and applied for strain measurements. Tests of two-directional four-point bending have shown usability of such FBG for two-axial in-plane strain measurement with a single FBG in iso-thermal conditions. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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14 pages, 4835 KiB

Open AccessFeature PaperArticle

Characterization of Graphite Oxide and Reduced Graphene Oxide Obtained from Different Graphite Precursors and Oxidized by Different Methods Using Raman Spectroscopy Statistical Analysis

by Roksana Muzyka, Sabina Drewniak, Tadeusz Pustelny, Marcin Sajdak and Łukasz Drewniak

Materials 2021, 14(4), 769; https://doi.org/10.3390/ma14040769 - 6 Feb 2021

Cited by 17 | Viewed by 2914

Abstract

In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were [...] Read more.

In this paper, various graphite oxide (GO) and reduced graphene oxide (rGO) preparation methods are analyzed. The obtained materials differed in their properties, including (among others) their oxygen contents. The chemical and structural properties of graphite, graphite oxides, and reduced graphene oxides were previously investigated using Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). In this paper, hierarchical clustering analysis (HCA) and analysis of variance (ANOVA) were used to trace the directions of changes of the selected parameters relative to a preparation method of such oxides. We showed that the oxidation methods affected the physicochemical properties of the final products. The aim of the research was the statistical analysis of the selected properties in order to use this information to design graphene oxide materials with properties relevant for specific applications (i.e., in gas sensors). Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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14 pages, 6067 KiB

Open AccessArticle

Thermo-Optical Switching Effect Based on a Tapered Optical Fiber and Higher Alkanes Doped with ZnS:Mn

by Joanna E. Moś, Karol A. Stasiewicz, Katarzyna Matras-Postołek and Leszek R. Jaroszewicz

Materials 2020, 13(21), 5044; https://doi.org/10.3390/ma13215044 - 9 Nov 2020

Cited by 5 | Viewed by 2248

Abstract

The paper investigates the effect of thermo-optic switching resulting from the hybrid combination of a tapered optical fiber (TOF) with alkanes doped with nanoparticles of zinc sulfide doped with manganese (ZnS:Mn NP). Presented measurements focused on controlling losses in an optical fiber by [...] Read more.

The paper investigates the effect of thermo-optic switching resulting from the hybrid combination of a tapered optical fiber (TOF) with alkanes doped with nanoparticles of zinc sulfide doped with manganese (ZnS:Mn NP). Presented measurements focused on controlling losses in an optical fiber by modification of a TOF cladding by the alkanes used, characterized by phase change. Temperature changes cause power transmission changes creating a switcher or a sensor working in an ON-OFF mode. Phase change temperatures and changes in the refractive index of the alkane used directly affected power switching. Alkanes were doped with ZnS:Mn NPs to change the hysteresis observed between ON-OFF modes in pure alkanes. The addition of nanoparticles (NPs) reduces the difference between phase changes due to improved thermal conductivity and introduces extra nucleating agents. Results are presented in the wide optical range of 550–1200 nm. In this investigation, hexadecane and heptadecane were a new cladding for TOF. The higher alkanes were doped with ZnS: Mn NPs in an alkane volume of 1 wt.% and 5 wt.%. The thermo-optic effect can be applied to manufacture a thermo-optic switcher or a temperature threshold sensor. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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14 pages, 2761 KiB

Open AccessArticle

SPR Effect Controlled by an Electric Field in a Tapered Optical Fiber Surrounded by a Low Refractive Index Nematic Liquid Crystal

by Joanna Korec, Karol A. Stasiewicz, Leszek R. Jaroszewicz and Katarzyna Garbat

Materials 2020, 13(21), 4942; https://doi.org/10.3390/ma13214942 - 3 Nov 2020

Cited by 11 | Viewed by 2721

Abstract

This paper presents the influence of a thin metal layer deposition on the surface of a tapered optical fiber surrounded by a low liquid crystal, on light propagation inside the taper structure. In this research, three types of liquid crystal cells were under [...] Read more.

This paper presents the influence of a thin metal layer deposition on the surface of a tapered optical fiber surrounded by a low liquid crystal, on light propagation inside the taper structure. In this research, three types of liquid crystal cells were under investigation: orthogonal, parallel, and twist. They differed by the rubbing direction of the electrodes in relation to the fiber axis determining the initial molecule arrangement inside the cell. Gold films with thickness d = 30 nm were deposited on the tapered fiber surface in the tapered waist area. Cells including a tapered optical fiber with no metallic layer were also examined and presented as a reference. All measurements were performed at room temperature for a different steering voltage U from 0 to 200 V, with and without any amplitude modulation with a frequency f = 5 Hz, and the wavelength λ range from 550 to 1200 nm. As a result, the resonant peaks were obtained, which depends on a liquid crystal cell type and steering voltage, as well. This paper shows the possibility of sensing the change of applied voltage by the constructed system. During measurements, additional effects as signal overlapping and intermodal interference were observed reducing measured voltage value. In the future, the improved, similar systems that will have a better response could be used as a sensor of factors to which liquid crystal (LC) will be sensitive, especially temperature and electric field. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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13 pages, 10564 KiB

Open AccessArticle

Luminescent Studies on Germanate Glasses Doped with Europium Ions for Photonic Applications

by Jacek Żmojda, Marcin Kochanowicz, Piotr Miluski, Piotr Golonko, Agata Baranowska, Tomasz Ragiń, Jan Dorosz, Marta Kuwik, Wojciech Pisarski, Joanna Pisarska, Renata Szal, Gabriela Mach, Bartosz Starzyk, Magdalena Leśniak, Maciej Sitarz and Dominik Dorosz

Materials 2020, 13(12), 2817; https://doi.org/10.3390/ma13122817 - 23 Jun 2020

Cited by 17 | Viewed by 3117

Abstract

Glass and ceramic materials doped with rare earth (RE) ions have gained wide interest in photonics as active materials for lasers, optical amplifiers, and luminescent sensors. The emission properties of RE-doped glasses depend on their chemical composition, but they can also be tailored [...] Read more.

Glass and ceramic materials doped with rare earth (RE) ions have gained wide interest in photonics as active materials for lasers, optical amplifiers, and luminescent sensors. The emission properties of RE-doped glasses depend on their chemical composition, but they can also be tailored by modifying the surrounding active ions. Typically, this is achieved through heat treatment (including continuous-wave and pulsed lasers) after establishing the ordering mechanisms in the particular glass–RE system. Within the known systems, silicate glasses predominate, while much less work relates to materials with lower energy phonons, which allow more efficient radiation sources to be constructed for photonic applications. In the present work, the luminescent and structural properties of germanate glasses modified with phosphate oxide doped with Eu³⁺ ions were investigated. Europium dopant was used as a “spectroscopic probe” in order to analyze the luminescence spectra, which characterizes the changes in the local site symmetries of Eu³⁺ ions. Based on the spectroscopic results, a strong influence of P₂O₅ content was observed on the excitation and luminescence spectra. The luminescence study of the most intense ⁵D₀→⁷F₂ (electric dipole) transition revealed that the increase in the P₂O₅ content leads to the linewidth reduction (from 15 nm to 10 nm) and the blue shift (~2 nm) of the emission peak. According to the crystal field theory, the introduction of P₂O₅ into the glass structure changes the splitting number of sublevels of the ⁵D₀→⁷F₁ (magnetic dipole) transition, confirming the higher polymerization of fabricated glass. The slightly different local environment of Eu³⁺ centers the results in a number of sites and causes inhomogeneous broadening of spectral lines. It was found that the local asymmetry ratio estimated by the relation of (⁵D₀→⁷F₂)/(⁵D₀→⁷F₁) transitions also confirms greater changes in local symmetry around Eu³⁺ ions. Our results indicate that modification of germanate glass by P₂O₅ allows control of their structural properties in order to functionalize the emissions for application as luminescent light sources and sensors. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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10 pages, 2892 KiB

Open AccessArticle

Characteristics of the Surface Plasmon–Polariton Resonance in a Metal Grating, as a Sensitive Element of Refractive Index Change

by Stefano Bellucci, O. Vernyhor, A. Bendziak, I. Yaremchuk, V. M. Fitio and Y. Bobitski

Materials 2020, 13(8), 1882; https://doi.org/10.3390/ma13081882 - 16 Apr 2020

Cited by 5 | Viewed by 2402

Abstract

The resonant excitation of surface plasmon–polariton waves in metal gratings with rectangular and sinusoidal relief was studied. The main characteristics of the resonant excitation of a surface plasmon–polariton wave were obtained using analytical methods due to the fact that the resonance is excited [...] Read more.

The resonant excitation of surface plasmon–polariton waves in metal gratings with rectangular and sinusoidal relief was studied. The main characteristics of the resonant excitation of a surface plasmon–polariton wave were obtained using analytical methods due to the fact that the resonance is excited at a grating thickness much smaller than a wavelength (1.064 µm). It is shown that the obtained results are very close to those calculated using numerical methods, e.g., Rigorous Coupled Wave Approach (RCWA). There is a small difference in the numerical data defined by both methods. The difference between the parameters for the two types of gratings is small. New analytical relationships of angular and spectral sensitivities with the change of the refractive index of the medium were obtained, depending on the grating period and the angle of incidence of the light beam. An analytical relationship between the spectral and angular widths of the resonant curves, at full width at half maximum, was determined. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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11 pages, 3525 KiB

Open AccessFeature PaperArticle

Technology of Polymer Microtips’ Manufacturing on the Ends of Multi-Mode Optical Fibers

by Monika Żuchowska (Chruściel), Paweł Marć, Iwona Jakubowska and Leszek R. Jaroszewicz

Materials 2020, 13(2), 416; https://doi.org/10.3390/ma13020416 - 16 Jan 2020

Cited by 4 | Viewed by 1973

Abstract

The technology of polymer microtips’ manufacturing on the ends of selected multi-mode fibers has been reported. The study’s key element was an extended description of technology parameters’ influence on the shape of these 3D microstructures. Basic technology parameters such as spectral characteristics of [...] Read more.

The technology of polymer microtips’ manufacturing on the ends of selected multi-mode fibers has been reported. The study’s key element was an extended description of technology parameters’ influence on the shape of these 3D microstructures. Basic technology parameters such as spectral characteristics of the light source, monomer mixture type, optical power, and exposure time were taken under consideration. Depending on those parameters, different shapes, sizes, and surface structures of microtips were obtained. The spectral characteristics of the light and optical power delivered to a monomer drop were identified as the most important parameters for the formation of the desired 3D shape of the microtip. Presented experimental results are the base for further studies directed to the application of these micro-elements in the fields of optical measurements and sensors’ technology. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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Review

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16 pages, 2770 KiB

Open AccessEditor’s ChoiceReview

Fibre Bragg Grating Based Acoustic Emission Measurement System for Structural Health Monitoring Applications

by Sagar Jinachandran and Ginu Rajan

Materials 2021, 14(4), 897; https://doi.org/10.3390/ma14040897 - 13 Feb 2021

Cited by 28 | Viewed by 3579

Abstract

Fiber Bragg grating (FBG)-based acoustic emission (AE) detection and monitoring is considered as a potential and emerging technology for structural health monitoring (SHM) applications. In this paper, an overview of the FBG-based AE monitoring system is presented, and various technologies and methods used [...] Read more.

Fiber Bragg grating (FBG)-based acoustic emission (AE) detection and monitoring is considered as a potential and emerging technology for structural health monitoring (SHM) applications. In this paper, an overview of the FBG-based AE monitoring system is presented, and various technologies and methods used for FBG AE interrogation systems are reviewed and discussed. Various commercial FBG AE sensing systems, SHM applications of FBG AE monitoring, and market potential and recent trends are also discussed. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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19 pages, 5172 KiB

Open AccessReview

Laser-Based Trace Gas Detection inside Hollow-Core Fibers: A Review

by Michal Nikodem

Materials 2020, 13(18), 3983; https://doi.org/10.3390/ma13183983 - 9 Sep 2020

Cited by 13 | Viewed by 3320

Abstract

Thanks to the guidance of an optical wave in air, hollow-core fibers may serve as sampling cells in an optical spectroscopic system. This paper reviews applications of hollow-core optical fibers to laser-based gas sensing. Three types of hollow-core fibers are discussed: Hollow capillary [...] Read more.

Thanks to the guidance of an optical wave in air, hollow-core fibers may serve as sampling cells in an optical spectroscopic system. This paper reviews applications of hollow-core optical fibers to laser-based gas sensing. Three types of hollow-core fibers are discussed: Hollow capillary waveguides, photonic band-gap fibers, and negative curvature fibers. Their advantages and drawbacks when used for laser-based trace gas detection are analyzed. Various examples of experimental sensing systems demonstrated in the literature over the past 20 years are discussed. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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17 pages, 2403 KiB

Open AccessReview

Hybrid Fiber Optic Sensor Systems in Structural Health Monitoring in Aircraft Structures

by Karolina Bednarska, Piotr Sobotka, Tomasz Ryszard Woliński, Oliwia Zakręcka, Wiktor Pomianek, Agnieszka Nocoń and Piotr Lesiak

Materials 2020, 13(10), 2249; https://doi.org/10.3390/ma13102249 - 13 May 2020

Cited by 24 | Viewed by 4181

Abstract

‘Smart’ structural health monitoring of composite materials with optical fiber sensors is becoming more and more important, especially in the aviation industry. This paper presents an overview of hybrid fiber-optic sensing systems based on scattering techniques, fiber Bragg gratings, interferometric techniques, and polarimetric [...] Read more.

‘Smart’ structural health monitoring of composite materials with optical fiber sensors is becoming more and more important, especially in the aviation industry. This paper presents an overview of hybrid fiber-optic sensing systems based on scattering techniques, fiber Bragg gratings, interferometric techniques, and polarimetric methods in structural health monitoring. The main purpose of this manuscript is to analyze the possibilities of using hybrid sensors based on fiber optics to monitor composite structures, with a particular emphasis on aircraft structures. Since it is difficult to indicate the most comprehensive approach due to different parameters of the described sensors, the review contains a detailed description of available solutions. We hope that this work will allow for a better and faster selection of the right solution for the problem at hand. Full article

(This article belongs to the Special Issue Recent Advances in Photonic Sensors)

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