Doped Glass Fiber Research Articles

Enhanced highly bismuth‐doped multicomponent phosphate glass fibers for broadband amplifiers

AbstractBismuth (Bi)‐doped glass fibers are being developed into next‐generation broadband amplifiers and tunable lasers. Yet, the well‐developed Bi‐doped fiber devices only realize silica‐based optical fibers prepared by the modified chemical vapor deposition method, which faces challenges such as low doping concentration, high cost, intricate device structure, and high preparation difficulty. Here, a novel highly Bi‐doped multicomponent phosphate glass was developed. The high ion solubility of this phosphate glass facilitates achieving a Bi doping concentration of 8 mol%. The introduction of aluminum nitride (a new reducing agent) can create a local reducing environment, further increasing the concentration of low‐valence near‐infrared (NIR) active Bi ions. Furthermore, the resulting enhanced highly Bi‐doped multicomponent phosphate glass with efficient 900–1600 nm NIR emission can be drawn into corresponding optical fibers by a rod‐in‐tube method. Broadband NIR amplified spontaneous emission with a 3 dB bandwidth of 275 nm was achieved in this new fiber. As far as we know, this is the first successful preparation of Bi‐doped multicomponent phosphate glass fiber. Our results indicate that this fiber will be a powerful alternative to Bi‐doped silica‐based fibers for the preparation of related Bi‐doped fiber devices.

Influence of multi‐walled carbon nanotubes on mechanical characteristics of glass fiber reinforced polymer composites: An experimental and analytical approach

AbstractAs a consequence of their magnificent performance like mechanical, electrical and chemical properties, multiwalled carbon nanotubes (MWCNTs) are widely used as a secondary reinforcement in composite field. It has been developed by arc discharging process under atmospheric pressure. Subsequently, MWCNTs doped nano‐composite were developed through hand lay‐up and followed by vacuum bagging techniques. Quasi – isotropic symmetrical laminate of eight layers (0/90)/(±45)/(±45)/(0/90)//(0/90)/(±45)/(±45)/(0/90) were fabricated under room temperature. To fabricate the composite laminates, purified MWCNTs were homogeneously dispersed in glass fiber reinforced epoxy with 0.5%, 1.25%, and 2 wt% loading. Tensile strength, tensile modulus, strain to failure and fracture behavior of unfilled and MWCNTs doped composite laminates were evaluated. Field emission scanning electron microscope (FE‐SEM) was employed to evaluate the structural and morphological characteristics of advanced nano‐composites. Reinforcement effect is found to be more pronounced in 1.25% MWCNTs embedded glass fiber reinforced polymer. This reinforcement effect was corroborated by tensile fractography which depicted by hackle region. Results indicated that tensile strength of 1.25 wt% nano‐composite increased by 47.36% with respect to 0.5 wt% MWCNT doped composites.Highlights Development of multi‐walled carbon nanotubes (MWCNTs) by arcing process. Fabrication of MWCNTs doped glass fiber reinforced polymer (GFRP) composites. Mechanical characterization of nano‐composites. Modeling of nano‐composites by Halpin‐Tsai equation. Fractrography of nano‐composites in details.

Optimization of Carbon Nanotube Doped Glass Fiber Reinforced Composite Material Using Taguchi Based Critic-CoCoSo Method

Bu makale, çok duvarlı karbon nanotüp (ÇDKNT) ile takviye edilmiş cam elyaf takviyeli polimer (CETP) kompozitlerin işleme verimliliğini, Taguchi ve Critic-CoCoso yöntemiyle değerlendirmesini sunmaktadır. Çalışmada delik delme işlemlerinde, farklı oranlarda çok duvarlı karbon nano tüp katkılı CETP malzemelerin, farklı takım tipiyle, işleme parametrelerinin, yüzey pürüzlülüğü, delaminasyon ve itme kuvveti üzerindeki etkileri araştırılmıştır. Deneyler Taguchi L27 ortogonal dizilimine göre planlanarak her bir kontrol parametresinin çıktılar üzerindeki etkileri S/N oranı yöntemiyle belirlenmiştir. 
 Yapılan çalışmada, CETP matrix composite materials ın işlenmesinde kullanılan parametrelerin optimum değerlerinin belirlenmesi amaçlanmıştır. Elde edilen çıktı sayısının birden fazla olması, farklı ve çelişkili cevap değerlerinin birbirleri üzerindeki etkilerinin de dikkate alınmasını gerektirmektedir. Bu sebeple bütün çıktıların tek bir amaç fonksiyonu olarak değerlendirilebilmesi için uygulamada sıklıkla kullanılan çok kriterli karar verme yöntemleri (ÇKKV) kullanılmaktadır. Önce tüm çıktı değerlerinin minimizasyonunu sağlamak için veriler Critic yöntemiyle ağırlıklandırılmış daha sonra da, çok kriterli karar verme yöntemlerinden CoCoSo yöntemi kullanılarak karşılaştırmalı analizi yapılmıştır.

Clustering engineering in tellurium-doped glass fiber for broadband optical amplification

Dense wavelength division multiplexing (DWDM) is recognized as one of the leading technologies for resolving the internet data traffic capacity issue. Although the successful development of rare-earth doped fiber amplifiers enables to achieve optical signal amplification in various telecommunication wavebands, their bandwidth is limited by the inherent sharp 4f electronic transition. Here, we propose the clustering engineering strategy in tellurium (Te)-doped glass fiber for broadband optical amplification. The correlation among the glass system, chemical state of Te and the optical response are systematically studied. The active Te-doped phosphate glass with intense and broadband luminescence is successfully achieved by control of the cluster state of the Te atoms. Subsequently, Te-activated phosphate fiber is successfully drawn and the optical response is transferred smoothly. Importantly, the amplified spontaneous emission and broadband optical amplification are achieved for the first time in Te-doped glass fiber. A small signal on-off gain covering an ultra-wide range of O + E + S + C + L bands is observed under excitation at 808 nm. Our results establish a critical step toward advancing Te-based photonic materials for novel broadband fiber amplifiers serviced in telecommunication system.

Mid-infrared emission from Dy3+ doped fluoroindate glass fiber

In this contribution a comprehensive spectroscopic study of Dy3+ doped fluoroindate glass samples and glass fiber is presented. The mid-infrared (MIR) emission from DyF3 doped bulk glass samples (0.2, 0.4, 0.8, 1.2, 1.4, 1.6 mol.%) is investigated when pumping at 1320 nm. A broadband mid-infrared emission spanning from 2800 nm to 3500 nm with 0.88 ms emission lifetime of the 6H13/2 level in 0.2 mol.% glass sample was observed. Also 0.2 mol.% of DyF3 doped fluoroindate glass fiber was drawn and its photoluminescence properties were studied showing the emission spectrum to 3500 nm and the 6H13/2 level lifetime of 0.91 ms. The results obtained show that fluoroindate glass is a good candidate for further development of tunable fiber lasers and broadband mid-infrared spontaneous emission fiber sources.

2.3 µm lasing in Tm3+ doped fluoroaluminate glass fibers with an upconversion pumping scheme

Tm3+ doped fluoroaluminate glass fibers are fabricated by using a rod-in-tube method based on AlF3-BaF2-YF3-MgF2-PbF2 glasses. By using a 1400/1570 nm dual-wavelength upconversion pump technique, lasing at ∼2.3 µm is obtained from a 2.3 m long Tm3+ doped fluoroaluminate glass fiber. The measured maximum unsaturated output power is ∼111 mW for a pump power of 1.5/0.14 W at 1400/1570 nm, and the corresponding slope efficiency is ∼11%. The effect of the gain fiber length on lasing at ∼2.3 µm is also investigated. Our results indicate that Tm3+ doped fluoroaluminate glass fibers are promising gain media for constructing ∼2.3 µm fiber lasers.

4.3 GHz fundamental repetition rate passively mode-locked fiber laser using a silicate-clad heavily Tm3+-doped germanate core multimaterial fiber.

We report a silicate-clad heavily Tm3+-doped germanate core multimaterial fiber that is successfully drawn by using a rod-in-tube method. This new fiber has a high gain per unit length of 6.11 dB/cm at 1.95 µm, which is, to the best of the authors' knowledge, the highest gain per unit length reported so far for Tm3+-doped glass fibers. By virtue of this high-gain glass fiber, an all-fiber-integrated passively mode-locked fiber laser with a fundamental repetition rate up to 4.3 GHz is demonstrated. Remarkably, the generated pulse operating at 1968 nm exhibits a signal-to-noise ratio of >76 dB in the radio-frequency domain. These results suggest that the silicate-clad heavily Tm3+-doped germanate core multimaterial fiber can act as a key building block for high repetition rate mode-locked fiber lasers at 2 µm.

Insights into the photodarkening mechanism of Tb3+/Al3+ co-doped silica glasses

In this work, Tb3+/Al3+ co-doped and Al3+ single doped silica glasses are taken as the research objects, and X-ray is used as the simulated light source to study the photodarkening mechanism. Detailed optical properties of the glasses before and after X-ray irradiation and the results of electron paramagnetic resonance (EPR) indicate that the photodarkening effect is attributed to the valence changes of Tb3+ ions and the energy transfer between Tb3+ ions and related defects. In addition, this work revealed the relationship between valence changes behavior of Tb3+ ions and various defects in glass matrix materials, deepening the understanding of the photodarkening mechanism in Tb3+ doped oxide glass. We envisage that our finding provides a depth-theoretical support for the synthesis of Tb3+-doped oxide matrix glass fibers with excellent optical and anti-photodarkening performance.

Effect of Doped Glass Fibers on Tensile and Shear Strengths and Microstructure of the Modified Shotcrete Material: An Experimental Study and a Simplified 2D Model

Shotcrete material has found extensive applications as a reinforcing material in the engineering sector. This study examined the effect of doped glass fibers on the mechanical performance of the modified shotcrete material composed of aeolian sand, fly ash, cement, quicklime, and doped glass fibers. Its tensile and shear strengths values were experimentally determined via a WAW-1000D computerized hydraulic universal tensile testing machine. Its microstructure was analyzed via a size analyzer, scanning electron microscope (SEM), and X-ray diffractometer (XRD). A 2D simplified mechanical model was elaborated to reflect the influence mechanism of the doped glass fibers on the mechanical performance of the modified shotcrete material. The experimental and mechanical analysis results indicated that, at the macroscopic scale, the experimental tensile and shear strengths of the shotcrete material doped with glass fibers were significantly higher than those of the undoped shotcrete material (by up to 310% and 596%, respectively). These results were in concert with the proposed model predictions, where the compound stresses in the shotcrete material were derived as the sum of the stress borne by the shotcrete material itself and the bridging stress exerted by the glass fibers. At the microscopic scale, SEM observations also revealed that the glass fibers were intertwined with each other and tightly enveloped by the shotcrete material particles within the modified shotcrete specimens, connecting the particles of different components into a whole and improving the overall mechanical strength. In addition, the relationships of the compound stress of the shotcrete material vs. embedment length, embedment angle, and cross-sectional area of the glass fibers were established. The research findings are considered instrumental in clarifying the mechanism by which the glass fibers influence the mechanical performance of shotcrete materials and optimize their solid waste (fly ash and quicklime) utilization.

Thermal analysis of multi-walled carbon nanotubes doped glass fiber reinforced polymer composites

Thermal characterization is one of the important aspects for evaluating the heat flux and decomposition kinetics of different materials, alloys and composites at different temperature. In this work Multi-scale nano-composites (MWCNTs/glass fiber/epoxy) were prepared by hand lay-up process followed by vacuum bagging method. Thermal properties of MWCNTs doped glass fiber reinforced polymer composites were evaluated by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). It has been found that in the presence of MWCNTs it is very difficult to break the polymeric chains and that leads to reduction in cross linking density and glass transition temperature of MWCNTs doped glass fiber reinforced polymer composites as compared to pristine one.

Effects of Doping Glass Fibers on the Early Strength of Sand-Based Cemented Paste Backfill for Solid Wastes Disposal in a Coal Mine

The mechanical strength of cemented paste backfill (CPB), especially the early compressive strength, is crucial for controlling the overlying rock movement. Therefore, improving the early compressive strength of CPB is a critical issue. In this study, the doped glass fibers’ effect on the macroscopic mechanical strength and microstructural features of the sand-based CPB (SCPB) with different curing ages was analyzed. The macroscopic properties and the microstructure of SCPB were characterized experimentally and analyzed via scanning electron microscopy. The results showed that slump sizes of SCPB specimens without and with doped glass fibers were 269 and 209 mm. Thus, doped glass fibers inhibited the SCPB transportability and significantly improved its early compressive strength. At curing ages of 1 d and 3 d, the compressive strength of SCPB specimens doped with glass fibers was improved by 679 and 278%, respectively, compared to the blank control group. As the curing age increased, the compressive strength improvement of the SCPB doped with glass fibers was gradually saturated. Finally, the correlation between macroscopic and microscopic properties of SCPB specimens was analyzed comparatively. Thus, the mechanism of doped glass fibers’ influencing the early compressive strength of the SCPB was revealed. The research findings provide theoretical guidance for improving the SCPB early compressive strength at the mining site with the CPB mining technique.

Luminescence Sensing Method for Degradation Analysis of Bioactive Glass Fibers.

The effects of Sm3+ content on the optical properties and bioactivity of 13-93 bioactive glass were presented. Sm3+ doped glass fibers drawn from bioactive glass were analyzed in simulated body fluid (SBF) for the determination of ion release. Optical analysis of the Sm3+ ions in bioactive glass fibers was used for degradation monitoring. While the fibers were immersed in SBF solution, changes in their luminescence spectra under 405 nm laser excitation were measured continuously for 48 h. The morphology of the fibers after the immersion process was determined by SEM/EDS. It was shown that the proposed approach to the analysis of changes in Sm3+ ion luminescence is a sensitive method for the monitoring of degradation processes and the formation of hydroxycarbonate-apatite (HCA) layers on glass fiber surfaces. SEM/EDS measurements showed a significant deterioration on the surface of the fibers and the formation of HCA on 13-93_02Sm bioactive glass. The optical analysis of the time constant indicated that bioactive glass fibers doped with 2 %mol Sm3+ degrade at a rate almost five times slower than 13-93_02Sm.

Controllable structural tailoring for enhanced ∼2 µm emission in heavily Tm3+-doped germanate glasses.

Heavily Tm3+-doped glass fibers are urgently desired for ∼2µm single-frequency fiber lasers and high-repetition-rate mode-locked fiber lasers. Here the structure of glass networks was tuned through controlling the numbers of non-bridging oxygens and bridging oxygens by adjusting the composition of the glasses, hence increasing the Tm3+ doping concentration of germanate glasses. The increased flexibility of the glass networks favors the distribution of Tm3+ ions to decrease fluorescence quenching, which was confirmed by the experimental and theoretical results. A heavily Tm3+ (9.8×1020ions/cm3)-doped germanate glass was successfully fabricated without quenching by tuning the components of the glass. To the best of our knowledge, the Tm3+ ion doping concentration is the highest reported level in Tm3+-doped glasses and fibers. The results suggest that the heavily Tm3+-doped germanate glass is highly promising for fabricating ∼2µm glass fibers with high gain per unit length.

3D printed Er3+/Yb3+ co-doped phosphosilicate glass based on sol-gel technology

We demonstrate a method to manufacture Er3+/Yb3+ co-doped phosphosilicate glass by the digital light processing (DLP) 3D printing based on sol-gel technology. The sol-gel technology was used to fabricate the rare earth ions doped photocurable printing ink to achieve excellent fluidity, tunable composition and uniform component distribution. Following photopolymerization of 3D printing, the parts underwent ageing and sintering at 1050 °C, which is much lower than conventional high temperature melting method (~1700 °C). To the best of our knowledge, this is the first time that rare earth ion doped multicomponent glass has been fabricated by 3D printing based on sol-gel technology. This method combined with fiber drawing technology provides a novel way to fabricate the rare earth ions doped glass fiber.

Fluorescent diamond microparticle doped glass fiber for magnetic field sensing

Diamond containing the nitrogen-vacancy (NV) center is emerging as a significant sensing platform. However, most NV sensors require microscopes to collect the fluorescence signals and therefore are limited to laboratory settings. By embedding micron-scale diamond particles at an annular interface within the cross section of a silicate glass fiber, we demonstrate a robust fiber material capable of sensing magnetic fields. Luminescence spectroscopy and electron spin resonance characterization reveal that the optical properties of NV centers in the diamond microcrystals are well preserved throughout the fiber drawing process. The hybrid fiber presents a low propagation loss of ∼4.0 dB/m in the NV emission spectral window, permitting remote monitoring of the optically detected magnetic resonance signals. We demonstrate NV-spin magnetic resonance readout through 50 cm of fiber. This study paves a way for the scalable fabrication of fiber-based diamond sensors for field-deployable quantum metrology applications.

Spatiotemporal modeling of mid-infrared photoluminescence from terbium(III) ion doped chalcogenide-selenide multimode fibers

A numerical model was developed to study the time dynamics of photoluminescence emitted by Tb3+ doped multimode chalcogenide-selenide glass fibers pumped by laser light at approximately 2 μm. The model consists of a set of partial differential equations (PDEs), which describe the temporal and spatial evolution of the photon density and level populations within the fiber. In order to solve numerically the PDEs a method of lines was applied. The modeling parameters were extracted from measurements and from data available in the literature. The numerical results obtained support experimental observations. In particular, the developed model reproduces the discrepancies that are observed between the photoluminescence decay curves obtained from different points along the fiber. The numerical analysis was also used to explain the source of these discrepancies.

Heavily Tb3+ doped multi-component phosphate glass fibers for green fiber lasers

Heavy rare earth (RE) ion doped glass fibers make it possible to obtain high gain and high output power per unit length. It is known that high concentration of RE ions can be incorporated into multi-component phosphate glasses, which are usually used to fabricate high performance gain fibers. However, the increasing doping concentration of RE ions is mainly limited by the concentration quenching effect and crystallization during the fiber drawing process by the conventional rod-in-tube technique. In this work, no fluorescence quenching was observed in the prepared multi-component phosphate glasses even when Tb3+ doping concentration reached 16 mol %. Then, heavily Tb3+ doped multi-component phosphate glass fibers with silicate glass cladding were successfully drawn by a molten core method, which can effectively solve the crystallization problem caused by heavily RE ions doping. To the best of our knowledge, 16 mol % is the record high Tb3+ ion in phosphate glass fibers for green laser. An intense 540 nm green emission with fluorescence lifetime as long as 1.85 ms was obtained from the as-drawn fibers, showing promising applications for green fiber lasers.

Wear and frictional study of MWCNT doped glass fiber reinforced polymer composite under different sliding conditions

Glass fiber reinforced polymer composites are a proven and successful alternative that have numerous advantage over traditional reinforcement method, giving material a longer service life. In this paper experimental investigation is done on GFRP/epoxy doped with 3 wt % of MWCNTs (multi-walled carbon nano tube, diameter of order nanometer). The aim of this research is to evaluate the feasibility of GFRP doped with MWCNT under different sliding conditions (a) dry (b) lubricated at three different loading conditions and sliding speeds. The sample was prepared by hand layup technique followed by vaccum bagging. The experiment was performed on a pin on disc type tribometer (TR-20, made by DUCOM) with a steel disc of HRC-60 acting as the counterface. Experiment shows that the wear rate increases with increasing in normal load. It was also observed that the wear rate and the coefficient of friction is minimum in lubricating conditions and maximum in dry environment. Morphology was examined with the help of FESEM analysis of MWCNT doped GFRP.

Numerical analysis of spontaneous mid-infrared light emission from terbium ion doped multimode chalcogenide fibers

In this contribution we use a numerical model to study the photoluminescence emitted by Tb3+ doped chalcogenide-selenide glass fibers pumped by laser light at approximately 3 µm. The model consists of the set of ordinary differential equations (ODEs), which describe the spatial evolution of the pump laser and MIR photoluminescence light within the fiber. The ODEs are coupled with the rate equations that describe the energy level populations. A self-consistent solution of the equation system yields the pump light, MIR photoluminescence and level population distribution within the fiber. Using the developed model we numerically calculate results and discuss the dependence of the output photoluminescence MIR power on the fiber optical loss, fiber length and pump wavelength.

Dual-wavelength Bi2Se3-based passively Q-switching Nd3+-doped glass all-fiber laser

We demonstrate a dual-wavelength passively Q-switched Nd3+-doped glass fiber laser using a few-layer topological insulator Bi2Se3 as a saturable absorber (SA) for the first time, to the best of our knowledge. The laser resonator is a simple and compact linear cavity using two fiber end-facet mirrors. The SA is fabricated by Bi2Se3/polyvinyl alcohol composite film. By inserting the SA into the laser cavity, a stable Q-switching operation is achieved with the shortest pulse width and maximum pulse repetition rate of 601 ns and 205.2 kHz, respectively. The maximum average output power and maximum pulse energy obtained are about 6.6 mW and 38.8 nJ, respectively.