P-doped Fiber Research Articles

Electrospinning construction of a Fe–Ni-based multicomponent hybrid as synergistic electrocatalyst for water electrolysis

Bimetallic multicomponent FeNi2P/FeNi3N/FeNi3/N, P-doped carbon fibers hybrid catalysts have been facilely prepared and the synergistic effect endowed the catalyst greatly improved electrocatalytic activities for water electrolysis.

Constructing globally consecutive 3D conductive network using P-doped biochar cotton fiber for superior performance of silicon-based anodes

The inferior conductivity and drastic volume expansion of silicon still remain the bottleneck in achieving high energy density Lithium-ion Batteries (LIBs). The design of the three-dimensional structure of electrodes by compositing silicon and carbon materials has been employed to tackle the above challenges, however, the exorbitant costs and the uncertainty of the conductive structure persist, leaving ample room for improvement. Herein, silicon nanoparticles were innovatively composited with eco-friendly biochar sourced from cotton to fabricate a 3D globally consecutive conductive network. The network serves a dual purpose: enhancing overall electrode conductivity and serving as a scaffold to maintain electrode integrity. The conductivity of the network was further augmented by introducing P-doping at the optimum doping temperature of 350 °C. Unlike the local conductive sites formed by the mere mixing of silicon and conductive agents, the consecutive network can affirm the improvement of the conductivity at a macro level. Moreover, first-principle calculations further validated that the rapid diffusion of Li+ is attributed to the tailored electronic microstructure and charge rearrangement of the fiber. The prepared consecutive conductive Si@P-doped carbonized cotton fiber anode outperforms the inconsecutive Si@Graphite anode in both cycling performance (capacity retention of 1777.15 mAh g–1 vs. 682.56 mAh g–1 after 150 cycles at 0.3 C) and rate performance (1244.24 mAh g–1 vs. 370.28 mAh g–1 at 2.0 C). The findings of this study may open up new avenues for the development of globally interconnected conductive networks in Si-based anodes, thereby enabling the fabrication of high-performance LIBs.

The Impact of Gamma Irradiation on Optical Fibers Identified Using Long Period Gratings

This paper compares the impact of gamma irradiation on various optical fibers, where the evolution in their optical properties could be identified using long period gratings (LPG) there induced. The LPGs were fabricated in broad spectrum of commercially available single-mode optical fibers - from standard to unconventional ones - using the electric arc discharge method. The fused silica fiber material contained such dopant as Ge, F, B/Ge and P. The gamma exposure has been performed with a dose rate of 2.6 kGy/h for 20 h (a total dose of 52 kGy). Subsequently, the recovery effect was monitored during the following 48 h. The wavelength shift and power change of the LPG attenuation bands during irradiation were investigated in real time. Moreover, to identify the impact of gamma treatment on the fiber properties, the thermal response of the gratings was studied before and after the irradiation. Depending on the fiber, significant differences have been observed in the grating responses. The highest radiation-dependent resonance wavelength shift has been found for B/Ge fiber (∼10 nm at maximum dose). Moreover, for these LPGs no response saturation within the applied dose levels has been observed together with very low recovery effect, what differentiate these LPGs from the other tested in this experiment. Finally, concerning the changes in optical power at the resonance wavelength, the LPG induced in P-doped fiber has shown a strong irradiation-induced attenuation reaching 18 dB with a negligible recovery effect. The findings reported in this work are crucial for optical fiber and optical fiber sensors application in environments exposed to radiation.

Low radiation dose calibration and theoretical model of an optical fiber dosimeter for the International Space Station.

The optical-fiber-based dosimeter of the LUMINA project was deployed in August 2021 in the International Space Station in the framework of the Alpha mission. The sensing elements of the dosimeter are P-doped optical fibers, which were proven to be excellent candidates for dosimetry applications. The twofold objective of this paper is to provide a theoretical model for the radiation response of the dosimeter and to report on the experimental work carried out at CERN for the qualification and calibration of the engineering model of the LUMINA dosimeter. Combining the theoretical response and experimental data, the calibration curve of the flight model is obtained. Finally, this study broadens the investigation of the room temperature radiation response of P-doped optical fibers in a range of dose rates 104 times lower than previously reported, from 21µGy(SiO2)/h to145mGy(SiO2)/h.

Ultra-short pulse burst laser around 1.98 µm obtained through an all-fiber nonlinear wavelength converter and Tm-doped fiber amplifier.

We report an all-fiber ultra-short pulse burst laser operating at around 1.98 µm that is obtained through a nonlinear wavelength converter and Tm-doped fiber amplifier. A mode-locked Er-doped fiber laser was first built and then amplified in subsequent amplifiers to an average power of 1.3 W. Ultra-short pulse burst output was achieved through a pulse multiplier and a fiber-pigtailed acousto-optic modulator. It was then injected into an all-fiber nonlinear wavelength converter constructed from P-doped fiber and Tm-doped fiber, obtaining an ultra-short pulse burst laser of 540 mW around 1.98 µm. Its average output power was then amplified to 4.33 W in a Tm-doped fiber amplifier with an intra-burst pulse repetition frequency of 0.9 GHz, a burst repetition frequency of 200 kHz, and a duty cycle of 2%, corresponding to about 200 pulses within each burst. This 1.98 µm pulse burst laser has enormous potential to be applied in bio-medical areas.

Core-shell structured Fe2P@TiO2/CNF anode nanocomposite fibers for efficient lithium/sodium-ion storage

Herein, a facile way was reported for fabrication of the anode nanocomposites with efficient lithium/sodium storage and excellent cycling stability. Iron phytate nanoparticles embedded in TiO2 (IP/TiO2) was prepared by coaxial electrospinning with the aid of PAN and PVP. N, P-doped Fe2P@TiO2 core-shell carbon nanofibers (Fe2P@TiO2/CNF) was prepared after heat treatment. When Fe2P@TiO2/CNF were introduced as a self-supporting anode in lithium/sodium-ion batteries, Fe2P core supplied high energy density, and N, P-doped carbon fiber could induce the structural defects, facilitate electron transport and improve electrical conductivity. Moreover, TiO2 shell inhibited volumetric expansion and pulverization of Fe2P core and improved the cycling stability of the anode. The Fe2P@TiO2/CNF electrode exhibited a large reversible capacity (LIB: 1175.7 and SIB: 519.8 mAh g−1), excellent cycling ability and outstanding rate performance. As anode in LIBs for Fe2P@TiO2/CNF, capacitance and diffusion control played important roles in Li+ intercalation and deintercalation, simultaneously. When Fe2P@TiO2/CNF anode was used in SIBs, capacitive control behavior occupied a major role and displayed outstanding electrochemical performance. This work offers a possibility for designing anode nanocomposite with outstanding capacity and cycling stability in lithium/sodium-ion batteries.

Non-Additive Effects of Ionizing Radiation and Hydrogen on Optical Fiber Attenuation

Optical fibers having various dopants (pure silica, fluorine, germanium and phosphorous) were consecutively exposed to ionizing radiation (gamma or beta) and hydrogen-rich environments. The attenuation spectra measured before, in-between and after the exposures displayed impacts of the radiation and hydrogen as optical loss factors. Their intermediate and ultimate losses were found to drastically depend upon the dopant type. The fibers with pure silica and fluorine-doped cores behaved as most immune to the applied conditions. The irradiated germanium-doped fibers were found to be much more sensitive to hydrogen than the as drawn fibers, which is explained by development of radiation-induced reactive sites in the fiber, that further promote interactions with hydrogen. In contrast, the irradiated phosphorous-doped fiber displayed a strong hydrogen-induced bleaching at longer wavelengths (>1000 nm), which was attributed to hydrogen reacted at P1 defect sites. A carbon coating present on one of the studied P-doped fibers was shown to prevent the bleaching.

Confinement of transition metal phosphides in N, P-doped electrospun carbon fibers for enhanced electrocatalytic hydrogen evolution

Research of highly dispersed transition metal phosphides (TMPs)-based catalysts for electrocatalytic hydrogen evolution is of great significance in the area of renewable energy. Herein, the high dispersion of FeNiP nanoparticles on N, P-doped electrospun carbon fibers was realized via the confinement effect induced by phytic acid (PA) and polyacrylonitrile (PAN), as well as electrospinning technique. PA and PAN were used as ligand for coordinating transition metal (TM) ions and carbon sources, respectively. In addition, the nucleophilic addition reaction between PA and PAN resulted in the cyclization of PAN and the further formation of a supramolecular network. Besides, the chelating ability of PA to TM ions was also modulated. Benefitting from the confinement effect, the optimized FeNiP/NPC800 exhibit good hydrogen evolution reaction (HER) activities for achieving a current density of 10 mA cm−2 at an overpotential of 277 mV in 0.5 M H2SO4.

Extreme Radiation Sensitivity of Ultra-Low Loss Pure-Silica-Core Optical Fibers at Low Dose Levels and Infrared Wavelengths.

We report here the response of a commercial ultra-low loss (ULL) single-mode (SM) pure silica core (PSC) fiber, the Vascade EX1000 fiber from Corning, associated with 0.16 dB/km losses at 1.55 µm to 40 keV X-rays at room temperature. Today, among all fiber types, the PSC or F-doped ones have been demonstrated to be the most tolerant to the radiation induced attenuation (RIA) phenomenon and are usually used to design radiation-hardened data links or fiber-based point or distributed sensors. The here investigated ULL-PSC showed, instead, surprisingly high RIA levels of ~3000 dB/km at 1310 nm and ~2000 dB/km at 1550 nm at a limited dose of 2 kGy(SiO2), exceeding the RIA measured in the P-doped SM fibers used for dosimetry for doses of ~500 Gy. Moreover, its RIA increased as a function of the dose with a saturation tendency at larger doses and quickly recovered after irradiation. Our study on the silica structure suggests that the very specific manufacturing process of the ULL-PSC fibers applied to reduce their intrinsic attenuation makes them highly vulnerable to radiations even at low doses. From the application point of view, this fiber cannot be used for data transfer or sensing in harsh environments, except as a very efficient radiation detector or beam monitor.

Ultraviolet-visible light-induced solarisation in silica-based optical fibres for indoor solar applications

The transmission performances of pure- and doped-silica (a-SiO2) optical fibres are compared during the exposure to a high-power broadband light source approximating the solar spectrum. From the Gaussian decomposition of the attenuation spectra, we found that Al- and P-doped fibres show a fast solarisation effect which leads to transmission degradation in the ultraviolet-visible range. Similarly, Ge-doped fibres undergo photoinduced colour-centre formation which, however, does not prevent visible-light propagation. One of the two tested pure-silica fibres results completely unaffected by light exposure whereas the other shows an absorption band probably due to the presence of chlorine impurities in the silica matrix.The reported results demonstrate the possibility of using commercial Ge-doped and pure-silica fibres for indoor lighting applications and fibre-based photovoltaic devices.

Crystallization and Thermal Stability of the P-Doped Basaltic Glass Fibers

The present research focuses on the influence of phosphorus oxide additives on the structure and thermal properties of the basalt glasses, produced in the form of fibers, i.e., at very high quenching speed. Basaltic glass fibers with various P2O5 contents were produced in two stages. In the first stage, the bulk glasses were prepared by adding variable amounts of (NH4)4P2O7 to milled natural andesitic basalt in order to obtain samples containing 2, 4, and 6 wt % P2O5. In the second stage, the glass fibers were obtained using a laboratory-scale system. Basalt glass fibers were characterized by Raman spectroscopy to obtain information on the structure of the obtained fibers, and by DSC-TG and XRD analyses to determine the change in crystallization mechanism of basaltic fibers. The hydrostatic weighing was used for the determination of glasses density. An increase in the content of P2O5 to 6 wt % leads to a decrease in the density of glass fibers due to the polymerizing effect of phosphorus oxide. The obtained X-ray diffraction patterns indicate that all samples are X-ray amorphous. The Raman results show that the decrease in the intensity of the line corresponding to vibrations of the structural units Q2 (about 920 cm–1) with respect to the line corresponding to Q3 (about 1125 cm–1) is related to an increase of P2O5 content. This also indicates the increase in polymerization degree of glass structure. DSC and XRD data also found out the change of phase transformations order with an increase of phosphorus oxide. The crystallization in natural and modified basalt glass fibers begins with spontaneous spinel-like phase formations that become nucleation sites for the precipitation of monoclinic pyroxene as a major phase. With an increase in the P2O5 content, there is a tendency to a decrease in the pyroxene at higher temperature, as a result of which, the hematite crystallizes at lower temperatures. That is associated with the activation of liquation processes, accompanied by the formation of amorphous phases with different viscosities with an increase in the concentration of P2O5. In conclusion, all the obtained data indicate the prospect of using the proposed approach to obtain basalt glass fibers with enhanced thermal and mechanical stability.

Controlling the Composition, Morphology, Porosity, and Surface Chemistry of Lignin-Based Electrospun Carbon Materials

Electrospinning is a suitable top-down technique for the preparation of polymeric fibers using high voltage electrical fields and solutions of the selected polymer of adequate viscosity and conductivity. The versatility of electrospinning allows accurate control of the morphology and composition of the fibers by a wide combination of operating conditions and small modifications of the spinneret and collector. Alcell lignin, which is extracted from lignocellulosic biomass using organic solvents through Organosolv process, is readily solved in ethanol, producing a solution that matches the requirements of the electrospinning process. This review summarizes the vast collection of carbon materials that can be obtained by processing lignin using electrohydrodynamic forces. The coaxial and triaxial electrospinning setups allow for obtaining fibers with two or more components hierchically arranged, the use of these configurations along with a carefully setting of the operating conditions (distance between needle and collector, voltage, flow rate,…) and the solution properties (conductivity, viscosity,…) facilitates the conformation of lignin into spheres, beaded fibers, straight fibers and fused meshes. All these morphologies can be implemented with solid or hollow bodies (i.e. enabling the production of tubes and hollow spheres) by using a sacrificial templating agent. Phosphoric acid can also be added in small amounts to the lignin solution, shortening the thermostabilization time of the fibers. The porosity of the phosphorus containing carbon fibers can be modified in the last stage of the preparation of carbon fibers by controlled gasification process, owing to the extended oxidation resistance of the P-doped fibers. Fibrillar carbon catalysts can be also obtained by one-pot preparation method, only solving small quantities of metallic salts in the lignin solution. In addition, alumina and silica-coated lignin fibers were produced by feeding a partially gelated solution of the respective alkoxide through the outer needle of the spinneret. The coated fibers can be carbonized without thermostabilization step, decreasing considerably the preparation time. All these carbon materials were successfully tested in different applications such as heterogeneous catalysis, energy storage and environmental protection, confirming that electrospinning is a powerful tool for maximizing the value of lignin as carbon precursor.

Combined Temperature Radiation Effects and Influence of Drawing Conditions on Phosphorous‐Doped Optical Fibers

This work focuses on the effects of high dose ionizing radiation, up to 10 MGy(SiO2), on P‐doped multimode optical fibers (OF) at different irradiation temperatures. The investigation is based on two complementary experimental techniques: radiation‐induced attenuation (RIA) measurements and electron paramagnetic resonance (EPR). The latter technique allows measuring the P1, P2, metastable‐POHC and stable‐POHC defects. Three OF samples are drawn from the same preform to evaluate the influence of changing their drawing conditions of the OFs on the radiation responses. This first study is performed under X‐rays at room temperature. The results are compared with the ones of γ‐rays irradiation. The latter allows to highlight a linear correlation between the NIR absorption band at 1.6 µm and the EPR signal of P1 defects, which supports D. Griscom's assignment of this absorption band to the P1 defect. The combined effect of ionizing radiation and irradiation temperature is also investigated extensively: online RIA measurements as well as post‐mortem EPR measurements for irradiation temperatures ranging from 25 to 280 °C and doses up to 3 MGy are performed. Both RIA and EPR data show that increasing the irradiation temperature can lead to an increased production of point defects and associated absorption bands. This result is of great importance for the employment of P‐doped OFs in radiation environment.

Synthesis of P-Doped and NiCo-Hybridized Graphene-Based Fibers for Flexible Asymmetrical Solid-State Micro-Energy Storage Device.

Fiber supercapacitors (FSCs) are promising energy storage devices in portable and wearable smart electronics. Currently, a major challenge for FSCs is simultaneously achieving high volumetric energy and power densities. Herein, the microscale fiber electrode is designed by using carbon fibers as substrates and capillary channels as microreactors to space-confined hydrothermal assembling. As P-doped graphene oxide/carbon fiber (PGO/CF) and NiCo2 O4 -based graphene oxide/carbon fiber (NCGO/CF) electrodes are successfully prepared, their unique hybrid structures exhibit a satisfactory electrochemical performance. An all-solid-state PGO/CF//NCGO/CF flexible asymmetric fiber supercapacitor (AFSC) based on the PGO/CF as the negative electrode, NCGO/CF hybrid electrode as the positive electrode, and poly(vinyl alcohol)/potassium hydroxide as the electrolyte is successfully assembled. The AFSC device delivers a higher volumetric energy density of 36.77 mW h cm-3 at a power density of 142.5 mW cm-3 . In addition, a double reference electrode system is adopted to analyze and reduce the IR drop, as well as effectively matching negative and positive electrodes, which is conducive for the optimization and improvement of energy density. For the AFSC device, its better flexibility and electrochemical properties create a promising potential for high-performance micro-supercapacitors. Furthermore, the introduction of the double reference electrode system provides an interesting method for the study on the electrochemical performances of two-electrode systems.

All-fiber dissipative soliton Raman laser based on phosphosilicate fiber.

We propose and demonstrate an all-fiber, synchronously pumped Raman laser based on phosphosilicate fiber (P-doped fiber) for deep tissue multiphoton imaging. The laser operates in a dissipative soliton regime and produces 2.2 ps chirped pulses (compressible to 317 fs) with energy up to 9.2 nJ, 0.3 W average power and at 1240 nm center wavelength. We have also found a new cross-polarization Raman lasing operation that offers access to an important wavelength near 930 nm for calcium imaging.

Arc-Induced Long Period Gratings in Phosphorus-Doped Fiber

Phosphorus-doped fibers have been reported and discussed in extensive works, as well as the radiation effects on their guiding features in different spectral ranges. However, the assessment of a technique enabling the fabrication of grating devices in this fiber is still an open issue. Here, for the first time to the best of our knowledge, we report on the fabrication of long period gratings (LPGs) in P-doped optical fiber by means of electric arc discharge technique (EAD). LPGs having periods of $500~\mu \text{m}$ and of $700~\mu \text{m}$ were presented, achieving the coupling up to LP06 cladding mode, attenuation bands with depth up to 35 dB, power losses lower than 0.5 dB, and devices length less than 20 mm. The results being also compared with numerical simulations. Moreover, the sensitivity characteristics to surrounding refractive index (SRI) and temperature changes of LPGs in P-doped fibers were also investigated. The SRI sensitivity of LP06 for SRI = 1.437 was about −478 nm/RIU, slightly higher than in standard fiber. Whereas, differently from standard Ge-doped fibers, a negative temperature response was found (−116 pm/°C) opening the possibility of new applications, for example for temperature compensation solutions.

Distributed Optical Fiber Radiation Sensing in a Mixed-Field Radiation Environment at CERN

In paper we present the results from distributed optical fiber radiation sensing measurements at the “Cern High energy AcceleRator Mixed field facility”, CHARM. The measurements have been carried out on a multimode (MM) radiation sensitive P-doped optical fiber. The distributed measurements have then been carried out by means of an Optical Time Domain Reflectometry (OTDR) system using different interrogation and acquisition parameters to understand their influence on the results. We demonstrate the possible localization of the total dose with meter scale spatial resolutions and dose resolution down to 10–15 Gy. The obtained distributed dose profiles are validated by the benchmark with RadFET dosimeters and appear very promising for high energy accelerators and physics experiments as well as for industrial applications.

Fiber-optic dosimeter based on radiation-induced attenuation in P-doped fiber: suppression of post-irradiation fading by using two working wavelengths in visible range

The design of a fiber-optic dosimeter, which determines the radiation dose from the difference of radiation-induced attenuation (RIA) Δα measured in a P-doped silica fiber at λ = 413 and 470 nm, is presented along with its first test results under gamma-radiation (dose rates 0.00064 and 0.0066 Gy/s, maximal dose ~2Gy). The dose-dependence of Δα as well as of RIA at individual wavelengths is found to be well described by a power law, the exponent lying in the range 0.90-0.94. In contrast to RIA at individual wavelengths, Δα is found not to depend on dose rate and to decay only slightly on termination of irradiation. Therefore, using Δα for dosimetry is argued to be more promising.

Waveband-switchable multiwavelength mixed-cascaded phosphosilicate raman fiber lasers

In this paper, the mixed-cascaded Raman scattering has been developed to investigate multiwavelength phosphosilicate Raman fiber lasers (MRFLs). With a tunable Yb3+-doped double-clad fiber laser (YDCFL) as the Raman pump source, we propose a compact and waveband-switchable (from the O- to U-band) MRFL using two- or three-mixed-cascaded Raman scattering of both SiO2/GeO2 and P2O5 in a P-doped fiber. We also confirm experimentally the feasibility of the proposed mixed-cascaded MRFL. When a 1064nm YDCFL was used to pump a spool of 1-km P-doped fiber, the compact linear-cavity MRFLs in the O- and L-band operation were obtained, respectively, based on the two- and three-mixed cascaded Raman scattering. Up to 16-wavelength stable oscillation around 1320nm has been observed with a spacing of 0.40nm and an extinction ratio >30dB. 12 lasing lines around 1601nm have also been achieved with a spacing of 0.58nm. The multiwavelength output powers as high as 108 and 138mW were obtained in the O- and L-band operations, respectively. The wavelength spacing of the MRFLs is flexibly adjustable, and the peak wavelength of each lasing line is continuously tunable over the wavelength spacing. In addition, the important characteristics of the mixed-cascaded MRFLs, including the linewidth broadening, the signal-to-noise ratio and the conversion efficiency, are discussed.

Combined High Dose and Temperature Radiation Effects on Multimode Silica-Based Optical Fibers

We investigate the response of Ge-doped, P-doped, pure-silica, or Fluorine-doped fibers to extreme environments combining doses up to MGy(SiO 2) level of 10 keV X-rays and temperatures between 25 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C and 300 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C. First, we evaluate their potential to serve either as parts of radiation tolerant optical or optoelectronic systems or at the opposite, for the most sensitive ones, as punctual or distributed dosimeters. Second, we improve our knowledge on combined ionizing radiations and temperature (R&T) effects on radiation-induced attenuation (RIA) by measuring the RIA spectra in the ultraviolet and visible domains varying the R&T conditions. Our results reveal the complex response of the tested fibers in such mixed environments. Increasing the temperature of irradiation increases or decreases the RIA values measured at 25 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C or sometimes has no impact at all. Furthermore, R&T effects are time dependent giving an impact of the temperature on RIA that evolves with the time of irradiation. The two observed transient and stationary regimes of temperature influence will make it very difficult to evaluate sensor vulnerability or the efficiency of hardening approaches without extensive test campaigns.