Silica Glass Fiber Research Articles

Laser properties of Nd3+/Yb3+ co-doped glass fiber around 1 µm

The interest in N d 3 + / Y b 3 + co-doping was initially motivated by the discovery of N d 3 + → Y b 3 + energy transfer in 1964, which profoundly influenced the motivation for subsequent research. Here, however, we propose a new mechanism based on an 808 nm and 975 nm dual-pumping scheme, in which the effect of N d 3 + → Y b 3 + energy transfer process is negligible. Gain spectrum modulation and its application in tunable dual-wavelength lasers around 1 µm were demonstrated in a 30-cm-long N d 3 + / Y b 3 + co-doped silica glass fiber. In addition, interesting laser efficiency improvements, thermal performance improvements, and even photodarkening resistance behavior were observed. This work broadens the knowledge of N d 3 + / Y b 3 + co-doping and may provide useful insights for exploring co-doping with rare-earth ions.

Spiral Structured Photonic Crystal Fiber-Based Plasmonic Sensor with Bimetallic Coating

We present a bimetallic coated, low-loss spiral lattice PCF sensor combined with SPR technology that achieves a high sensitivity. The sensing performance and properties of our recommended sensor are realized numerically by the Finite Element Method. Gold is utilized as the plasmonic layer and titanium Oxide (TiO2), which is sandwiched between the silica glass fiber and the gold coating, forming the bimetallic surface. As TiO2 has a high refractive index, they create a strong surface plasmon wave in the plasmonic region that attracts the evanescent field originating from the core region and increases the coupling effect plasmonic and core mode. Hence, the bimetallic coating is performed to achieve better sensing performance and strengthen the SPR process for the presented sensor. The presented sensor’s nominal tolerance is 12,000 nm/RIU for x-polarization to 11,000 MHz for y-polarization. The presented sensor is intended to be used in several applications and sensing fields due to its high sensitivity.

A Literature Review on Development and Performance Assessment of High Performance Concrete with Silica Fume and Glass Fiber

A Literature Review on Development and Performance Assessment of High Performance Concrete with Silica Fume and Glass Fiber

2.6-GHz fundamental repetition rate, Q-switched mode-locking Nd[formula omitted]-doped single-mode silica fiber laser, fabricated by zeolite method

We successfully constructed a pulse laser whose fundamental repetition rate is 2.6-GHz in Q-switched mode-lock oscillation. To the best of our knowledge, this is the highest repetition rate among silica glass fiber lasers. The laser cavity was constructed by a 40-mm-long Nd3+-doped single-mode silica glass fiber (Nd-SMF) and a SESAM as a saturable absorber. The core glass of the Nd-SMF was fabricated by a zeolite method and its concentration of Nd2O3 was 1.25 wt%. The maximum laser power reached 27.2 mW, and its slope efficiency and lasing thresholds were 19.6% and 7.3 mW. The peak wavelength of the oscillation was 1062.7 nm. The RF spectrum and the time-dependent waveform from a 20-GHz-bandwidth oscilloscope show a 2.6-GHz repetition rate of an Nd-SMF laser. We also discuss the conditions for achieving a CW-mode-lock (CML) oscillation, which is critical laser output Pout of 180 mW. Such a simple multi-GHz repetition rate laser will be available to make a compact frequency comb or a laser oscillator that will achieve ablation-cooled material removal in laser processing.

Molecular dynamics study on the co‐doping effect of Al2O3 and fluorine to reduce Rayleigh scattering of silica glass

AbstractFurther attenuation of Rayleigh scattering of silica glass is required to extend the capacity of long‐distance optical fiber communication. To theoretically examine the effect of aluminum and fluorine co‐doping on the density fluctuations of silica glass, which is related to Rayleigh scattering, a set of force‐matching potentials (FMP) for simulating F‐doped aluminosilicates was developed using Bayesian optimization based on density functional theory calculations. Molecular dynamics (MD) simulations with the new FMP could evaluate the densities of silica glasses to which a small amount of fluorine was doped and those of aluminosilicate glasses with a wide range of aluminum contents within reasonable accuracy. The FMP successfully represents the changing role of aluminum from a network former without a compensating cation (threefold coordination) to that with a compensating cation and a charge compensator in the aluminosilicates. Indeed, relative concentrations of four, five, and sixfold‐coordinated aluminum observed by NMR measurements were reproduced better than the original Teter potential at a high aluminum content. At an aluminum content lower than 1 mol%, threefold‐coordinated aluminum was observed, which is consistent with ESR measurements. After careful validations of the FMP, the effect of the co‐doping of alumina and fluorine on the density fluctuations of silica glass was computationally examined. Consequently, it was expected that the co‐doping might not sufficiently attenuate the Rayleigh scattering, even though 1 wt% fluorine would be able to reduce the density fluctuations of aluminosilicate glasses for some extent. This is because more alumina‐doping increases density fluctuations of silica glass if the drawing temperature and procedure are the same with those for silica glass fiber. Thereby, a possible fabrication process to sufficiently attenuate the Rayleigh scattering of the F‐doped aluminosilicate glass was proposed, according to the density fluctuation analysis at high temperature.

Photoelastic confirmation of surface stress relaxation in silica glasses: Fiber bending and rod torsion

AbstractSilica glass samples were given various heat treatments under stress at low temperatures and subsequently their residual stress distributions in terms of retardance were observed using a polarized light microscope, confirming previously reported fast surface stress relaxation while providing more detailed characterization. Retardance profiles of silica glass fibers heat‐treated under a constant bending strain in the presence of atmospheric water vapor were measured and fit to a previously developed diffusion‐based relaxation model. The retardance of a cross‐section of a silica glass rod heat‐treated at 650°C in lab air under applied torsional shear strain was also measured to confirm the presence of residual surface shear stress which was predicted by the decrease of torque with time for the rod. Together, these results confirm the low‐temperature fast surface stress relaxation which occurs when water vapor is present for both bending and shear stresses.

Fiber optic propagation problems and signal bandwidth measurements under high temperature and high dopant germanium ratios

Abstract This study presents fiber optic losses/dispersion and signals bandwidth measurements under high temperature and high dopant germanium ratios variations for ultra-long haul distances without amplification stage. The fiber losses, fiber dispersion, and total fiber data rates are estimated and compared with the previous results under room temperature and high germanium dopant ratios to silica glass fiber. Then the model is extended for ultra-fiber transmission distances up to 500 km under high-temperature variations without using any amplification stage. The fiber losses/dispersion coefficient is degraded, and the total fiber data rates are enhanced with the increment of high dopant ratios of germanium.

ИССЛЕДОВАНИЕ ХИМИЧЕСКОГО ВЗАИМОДЕЙСТВИЯ СТЕКЛОВОЛОКНА С ПРОДУКТАМИ ГИДРАТАЦИИ ЦЕМЕНТА

Reinforcement of concrete with fiberglass improves the performance properties of concrete. The object of the study is fiberglass concrete, where Portland cement or alumina cement is used as a binder, and silica fiberglass is used as a filler. The chemical and phase compositions of Portland cement and alumina cement have been studied. The influence of the products of hydration of Portland cement and alumina cement on the chemical resistance of glass fiber has been investigated. The phase composition of Portland cement and alumina cement after hydration is studied using X-ray phase analysis. It is revealed that the following phases are present in alumina cement: CaОAl2O3, MgОAl2O3, 12CaO•7Al2O3, 2CaO•Al2O3•SiO, the phase composition of Portland cement is Ca6Al2(SO4)3(OH)12•12H2O, Ca2,25(Si3O7,5(OH)1,5)•(H2O), Ca(OH)2, CaCO3. It has been found that when hydrated, Portland cement has a negative effect on fiberglass due to the presence of Ca(OH)2 in it. The phase composition of the alumina cement after hydration shows the absence of Ca(OH)2. The chemical composition of fiberglass is investigated using X-ray fluorescence analysis. The use of alumina cement when using non-alkali-resistant fiberglass in a composite material is substantiated. The study of the stability of fiberglass in the environment of cement drawing has been carried out. Studies have shown that KV-11 grade fiberglass interacted less with hydration products of alumina cement than with hydration products of Portland cement.

Single-Frequency Nd3+-Doped Phosphate Fiber Laser at 915 nm

Single-frequency distributed Bragg reflector fiber laser at 915 nm was demonstrated by using a 2.5-cm long Nd3+-doped phosphate fiber as the gain medium. An output power of 13.5 mW was obtained at an absorbed pump power of 240 mW. Our experimental results show that Nd3+-doped phosphate glass fiber is more efficient than Nd3+-doped silica glass fiber for single-frequency laser operation in the 900 nm wavelength range.

Enhancing the Hardened Properties of Recycled Concrete (RC) through Synergistic Incorporation of Fiber Reinforcement and Silica Fume.

Portland cement concrete is fragile in tension and it has numerous negative impacts on the environment. To deal with these issues, both fiber reinforcement and recycled materials can be utilized to manufacture sustainable and ductile concrete. In this study, the synergistic effects of high-performance mineral admixture silica fume and glass fiber reinforcement were investigated on the hardened properties of RC. For this purpose, two concrete mix families, namely, NC and RC were prepared. To understand the benefits of synergistic utilization of glass fiber and silica fume, in both NC and RC, 0.5% glass fiber was incorporated with three different levels of silica fume. i.e., 0%, 5%, and 10%. Both strength and permeability-related durability properties were investigated. Results revealed that combined incorporation of 0.5% fiber and 10% silica fume can help in the production of RC having better mechanical and durability performance compared to reference “NC”. Simultaneous incorporation of silica fume and glass fiber produces a combined effect greater than their individual effects on both mechanical and permeability properties of concrete. Silica fume plays a very dominant and positive role in the development of CS, WA, and CIPR of RC, whereas glass fiber plays a vital role in upgrading STS and FS of RC and whereas, with the addition of 0.5% glass fiber, RC can yield 8–9 times higher flexural toughness than that of the plain NC.

Experimental Study of the Combined Use of Fiber and Nano Silica Particles on the Properties of Lightweight Self Compacting Concrete

In fiber concretes, microcracks in the boundary area between the cement paste and the surface of aggregates or fibers are higher. Natural and artificial pozzolans can be used for reinforcing this area. In this research, the combination of glass fiber, zeolite, and nano silica particles were used in lightweight self-compacting concrete containing scoria. Fiber volume fractions between 0% to 1.5% in combination with 0% to 6% nano silica particles were examined. The scoria aggregates and zeolite were considered constant in all mixes. The fresh and hardened properties of specimens were evaluated using T50, slump flow, V-funnel, L-box, compressive strength, splitting tensile strength, flexural strength, ultrasonic, electrical resistivity, and water absorption tests. Also, the microstructure of concrete was investigated using scanning electron micrograph images. The combined use of nano silica particles and glass fiber increased the splitting tensile strength by about 3 to 56%. Also, the use of nano silica particles increased electrical resistivity by 136 to 194%. Nano silica particles, due to their high specific surface and high reactivity, result in consuming calcium hydroxide that is quickly organized within the hydration, filling pores of the calcium silicate gel structure and eventually producing more and more compacting hydrated products.

Short-length CW laser of Nd[formula omitted] heavily doped single-mode silica glass fiber fabricated by zeolite method

We constructed a CW fiber laser using a 40-mm-long Nd3+ heavily doped silica glass single-mode fiber (Nd-SMF). Its core glass was fabricated by the zeolite method, and its Nd2O3 doped density was measured as 1.25 wt%. Nd-SMF also demonstrated laser oscillation. The laser power reached 19.7 mW and its slope efficiency and laser threshold were 14.6% and 22.0 mW, respectively. Such a short single-mode fiber will help us easily make a high repetition rate over GHz and a compact oscillator with adequate saturable absorbers. An Nd-SMF laser has the potential to achieve laser miniaturization and high repetitive pulsed oscillation.

Evaluation of Flat Gain with RAMAN-Thulium Doped Silica Glass Fiber Hybrid Optical Amplifier in Some Band Spectrum for Super Dense Wavelength Division Multiplexing System

The performance of RAMAN-TDSGF hybrid optical amplifier (HOA) has been examined in the context of gain and noise figure (NF) for 400 × 10 Gbps super dense wavelength division multiplexing (SD-WDM) system. Characteristics of this novel HOA has also compared with RAMAN-EDFA-RAMAN, RAMAN-EDFA and RAMAN-RAMAN HOA for the range of 1530 nm to 1665, and 1530 nm to 1586 nm respectively. Best rating in terms of maximum gain of 35.9 dB and noise figure of 3.2 dB have recorded from RAMAN-TDSGF HOA with the variation of 0.025 dB than the other HOAs. Moreover this paper also has shown the worst response from RAMAN-RAMAN HOA for super dense optical communication system.

Deformation and Fracture of Silica Glass Fiber Under Sharp Wedge-Indentation

Wedge-indentation provides a means for overcoming some of the problems of normal indentation on curved glass surfaces. In particular, it enables testing in comparably homogenous, two-dimensional stress fields, avoiding the effects of the sharp edges of pyramidal indenters. Adjusting the wedge’s opening angle, length and orientation relative to the fiber surface enables highly reproducible studies of material deformation, surface crack initiation and effects of fiber anisotropy.

Machining and Characterization of Multidirectional Hybrid Silica Glass Fiber Reinforced Composite Laminates Using Abrasive Jet Machining

Machining of multidirectional Hybrid Fiber Reinforced Composite (HFRC) is a challenging task because of defects like matrix cracking, fiber pullouts, delamination, burr formation, and heat affected zones. The current study is focused on machining and characterization of in-house fabricated HFRC made of carbon and silica glass fiber using Abrasive Jet Machining (AJM). Machining of holes in fabricated multidirectional HFRC has been carried out using a set of input machining parameters -air pressure, abrasive grit size, and standoff distance. The output responses selected for the experiment are material removal rate, circularity, Depth Averaged Radial Overcut (DAROC), Taper Angle (TA), and Surface Roughness (Ra.) A novel technique has been contrived for measuring DAROC by using Computerized Tomography images. At the same time, the microstructure, surface roughness, and burr height of the machined samples are carried out using High-resolution Scanning Electron Microscope (HRSEM) images and 3D-profilometer images. Subsequently, the machining parameters are optimized using multi-objective GRA to strike a balance between the output parameters. The obtained results indicated the absence of defects like delamination, burr formation, heat affected zones in the machined samples. The outcome of the experiment corroborates the application suitability of the AJM process for machining multidirectional HFRC used in industrial and commercial products.

Electron energy loss spectra from silica glass optical fibers

AbstractTo investigate the possible structural differences between silica glass fibers and bulk silica glasses, electron energy loss spectroscopy (EELS) has been used to study the short‐range and medium‐range structures of both forms of silica glasses. The short‐range structure of silica glass, such as the coordination and symmetry, was investigated by the energy loss near edge structure (ELNES) of Si L2,3‐edges. The ordering structure in the medium‐range was analyzed by the exponential optical absorption edge also known as the Urbach edge of the glasses. The optical absorption data were obtained from the low energy loss spectrum of EELS through Kramers‐Kronig analysis. The results show that silica fiber has the same short‐range structure as the bulk specimen, but is significantly more disordered than the bulk glasses.

Conquering the Rayleigh Scattering Limit of Silica Glass Fiber at Visible Wavelengths with a Hollow‐Core Fiber Approach

AbstractThe performance of optical fiber communication, laser, and sensing systems is ultimately limited by the attenuation of optical fiber, which cannot be lower than the barrier set by Rayleigh scattering in bulk silica glass. In this work, the longstanding Rayleigh scattering limit is conquered by using a hollow‐core fiber (HCF). Two visible‐guiding hollow‐core conjoined‐tube anti‐resonant fibers are successfully fabricated and exhibit overall losses of 3.8 dB km−1 at 680 nm and 4.9 dB km−1 at 558 nm, respectively. The latter surpasses the Rayleigh scattering limit of silica glass fiber by 2 dB km−1 at the corresponding wavelength. Numerical simulations indicate that the loss level the authors achieve is still much higher than the ultimate loss limit caused by surface scattering of this HCF geometry, leaving plenty of room for further refinement.

Modeling birefringence in SiO2 glass fiber using surface stress relaxation

AbstractThe retardance of silica glass fibers was evaluated using photoelastic techniques. Here, surface birefringence in glass fibers is shown to be a consequence of surface stress relaxation for as‐received fibers drawn from Suprasil II. The surface features of the birefringent fibers were compared to a model of the residual axial stress profile resulting from a diffusion‐controlled surface stress relaxation. Additionally, a uniform birefringence in the fiber equivalent to a constant tensile stress was recognized and attributed to structural anisotropy produced during fiber drawing. The contribution of structural anisotropy to the observed birefringence remained constant as the surface features were successively etched away. Surface compressive stress generation was also observed, as retardance corresponding to a surface compressive stress was found to increase with applied tensile stress during short heat treatments. Significant features of the retardance profile in as‐received silica glass fibers, with a thin surface compressive stress layer and compensating interior tensile stress, agreed with the residual stress profiles predicted by the surface stress relaxation model after correcting for this observed structural anisotropy.

Manufacture and spectroscopic analysis of Tm3+-doped silica glass and microstructure optical fiber through the laser sintering technique

We demonstrated how a Tm3+-doped silica glass rod was successfully manufactured by the laser sintering technique and made into a Tm3+-doped microstructure optical fiber by the stack-capillary-draw method. Based on the absorption spectrum, the core glass shows outstanding spectroscopic properties through Judd-Ofelt analysis. The fiber core-cladding structure was preserved completely without any crystallization in the core. Besides, a self-built fiber laser at 1.95 μm produces 740 mW output power with a slope efficiency of 16.73%. The results prove that our laser sintering technique is a promising preparation method to acquire fiber materials for a 2.0 μm laser.

Mode instabilities in Yb:YAG crystalline fiber amplifiers.

Mode instabilities (MI) threshold in the Yb:YAG crystalline fiber amplifier is simulated by a full numerical model. The propagation of signal fields is simulated by the finite-difference beam-propagation method combined with the rate equations, and the time-dependent heat equation is solved by the alternating-direction-implicit method. Considering the strong temperature-dependent laser performance of Yb:YAG, an iterative method is applied to reach the steady state of Yb:YAG, the crystalline fiber amplifier, before the simulation of MI behavior. The simulated MI thresholds in Yb:YAG crystalline fiber amplifiers are found to be at least 28 times of those in Yb-doped silica-glass fiber amplifiers, up to tens of kilowatts. Simulation results show that, in addition to the expected higher thermal conductivity and lower thermo-optic coefficient, strong gain saturation also plays an important role in the high MI threshold of the Yb:YAG crystalline fiber.