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In the present paper, a series of plate impact shock-reshock and shock-release experiments were conducted to study the critical shear strength of a S2 glass fiber reinforced polymer (GRP) composite under shock compression levels ranging from 0.8 to 1.8 GPa. The GRP was fabricated at ARL, Aberdeen, using S2 glass woven roving in a Cycom 4102 polyester resin matrix. The experiments were conducted by using an 82.5 mm bore single-stage gas gun at Case Western Reserve University. In order to conduct shock-reshock and shock-release experiments a dual flyer plate assembly was utilized. The shock-reshock experiments were conducted by using a projectile faced with GRP and backed with a relatively high shock impedance Al 6061-T6 plate; while for the shock-release experiments the GRP was backed by a relatively lower impedance polymethyl methacrylate backup flyer plate. A multibeam velocity interferometer was used to measure the particle velocity profile at the rear surface of the target plate. By using self-consistent technique procedure described by Asay and Chabbildas [Shock Waves and High-Strain-Rate Phenomena, in Metals, edited by M. M. Myers and L. E. Murr (Plenum, New York, 1981), pp. 417–431], the critical shear strength of the GRP (2τc) was determined for impact stresses in the range of 0.8 to 1.8 GPa. The results show that the critical shear strength of the GRP is increased from 0.108 GPa to 0.682 GPa when the impact stress is increased from 0.8 to 1.8 GPa. The increase in critical shear strength may be attributed to rate-dependence and/or pressure dependent yield behavior of the GRP. [ABSTRACT FROM AUTHOR]

Ytterbium (Yb) doped fiber lasers are known to be affected by the creation of color centers during lasing (so-called photodarkening (PD)). In a previous work, this defect creation was investigated from a spectroscopic point of view, showing the presence of traces (ppb) of thulium (Tm) in the Yb doped fiber. It was shown that Tm has a strong impact on the defect creation process involved in PD. In this paper, we compare the results from the literature with our Tm hypothesis, without finding any contradiction. Moreover, this hypothesis can be an explanation for the discrepancies in the literature. [ABSTRACT FROM AUTHOR]

Two-dimensional MXenes have shown impressive semiconductor-like properties associated with their ultrathin-atomic-layer structure. Herein, ZnO/Ti3C2Tx hybrid structures were fabricated by a simple dipping method. Photodetectors (PDs) made of ZnO/Ti3C2Tx hybrid on glass fiber exhibit significantly enhanced photodetect ability. The responsivity of ZnO/Ti3C2Tx PD is 5.05 A/W when illuminated by 365 nm light (0.28 mW/cm2) at a bias of 5 V, which is 360 times that of ZnO PD (0.014 A/W). The synergistic effect of the formation of the novel heterostructure and the high conductivity of Ti3C2Tx played a major role in the enhanced photodetect performance. The high responsivity of 7.01 A/W and the high external quantum efficiency of 2386% for ZnO/Ti3C2Tx PD give it great potential for a UV light photoswitch and image sensor. This work sheds light on the utilization of two-dimensional MXene materials in high-performance optoelectronic devices. [ABSTRACT FROM AUTHOR]

ErF3-doped TeO2–Ga2O3–BaF2–AlF3–Y2O3 (TGBAY) glasses with high fluorescence efficiency and a high thermal damage threshold were developed for potential mid-infrared fiber laser applications. A model 2.7-μm fiber laser based on this material was analyzed using rate and propagation equations. Under 808 and 980 nm laser pumping, fluorescence emissions with central wavelength at 1.55 and 2.73 μm were detected. Based on the Judd–Ofelt (J–O) theory, the intensity parameters (Ωλ, λ = 2, 4, and 6) and radiative transition property were calculated and characterized through absorption and emission spectra. The results indicated that tellurite–gallium oxyfluoride glass had a high glass transition temperature (Tg, ∼391 °C), large emission cross sections at 1.55 μm (6.32 × 10−21 cm2) and 2.73 μm (9.68 × 10−21 cm2) as well as a longer fluorescence lifetime (6.84 ms at 1.55 μm and 262 μs at 2.73 μm) relative to the conventional Er3+-doped tellurite glass. The temperature dependence of the emission spectra indicated that TGBAY-2Er glass was more favorable to achieve infrared emission at low temperatures. Numerical simulation revealed the feasibility of achieving a ∼2.7 μm fiber laser operation based on the developed Er3+-doped tellurite–gallium oxyfluoride glass fiber. [ABSTRACT FROM AUTHOR]

We report magnetic, dielectric, magnetodielectric, and magnetocaloric responses of La2CoMnO6 (LCMO) and Sr doped La2−xSrxCoMnO6 (x = 0.5 and 1.0) induced by antisite disorder. The antisite disorder is enhanced with Sr-doping at La-sites. Co ions have mixed valence states on Sr-doping, with Co3+ and Co2+. Mn is present in mixed valence of Mn4+ and Mn3+ states with Sr doping. The dielectric constant of Sr doped LCMO was found to increase, whereas the magnetodielectric coupling was found suppressed due to the increase of antisite disorder. The magnetic field-dependent magnetodielectric effect clearly shows M2 behavior for all the samples in the field range of 0 to ±6 T in their respective ferroic phases. All the samples show spin glass like ordering in the ground state. We also report the magnetic entropy change in magnetoelectric material La2−xSrxCoMnO6 (x = 0, 1.0) samples. The change in magnetic entropy ΔSm originates mainly from the combined effect of the ferromagnetic/antiferromagnetic interaction and the magnetodielectric effect in La2−xSrxCoMnO6 (x = 0, 1.0). The observed value of the magnetocaloric effect (1.2 J/kg K) for x = 1.0 is likely to originate from the antisite disordered phases near Curie temperature. [ABSTRACT FROM AUTHOR]

Solid phase diffusion properties of three typical n-type dopants (P, As, and Sb) in Ge have been studied through experimental depth profiles of dopants diffused from spin on glass (SOG) films. Numerical calculations of dopant profiles in Ge are performed to extract the diffusion constant through comparison with the experimental profiles. It is pointed out that experimental results of diffusion at low temperature are important to correctly examine the influence of negative charge states of a vacancy on dopant diffusion. It is found that vacancies with the charge states of −2 mediate the diffusion of P and As without implantation-induced defects. The diffusion constants of P and As, obtained in this study, are larger than those for intrinsic diffusion, while that of Sb is almost the same as that for intrinsic diffusion. The present larger diffusion constants of P and As can be explained by the supply of vacancies from Ge surfaces via E-centers during diffusion from SOG. [ABSTRACT FROM AUTHOR]

Several methods have been reported in the literature using pulsed thermography for quantitative measurement of defect depth or sample thickness. In this paper, based on the analysis of a theoretical one-dimensional solution of pulsed thermography, a new method was proposed to first multiply the original temperature decay with square root of the corresponding time to obtain a monotonically increasing function f. A specific time was obtained by setting f equals to a predefined value, the theoretical model shows that the obtained specific time has linear relation with square of defect depth, which was verified with the experimental results of one aluminum and one glass fiber reinforced polymer specimen machined with six flat-bottom wedges as simulated defects. This linearity can be used for defect depth prediction in pulsed thermography. [ABSTRACT FROM AUTHOR]

An Yb3+ to Tm3+ energy-transfer quantum yield close to one has been found in phase-separated yttrium-alumina silicate optical fiber preform glasses. Optical absorption, luminescence, lifetime measurements, and rare-earth concentration dependence have been performed to investigate the feasibility of efficient blue upconversion fiber lasers through convenient Yb3+ sensitation. Luminescence decay measurements have demonstrated the co-existence of two phases. One of the phases is characterized by an yttrium-rich composition. Most of the RE ions partition into the yttrium-rich phase and produce the intense upconversion emission. [ABSTRACT FROM AUTHOR]

We used wet treatment to immobilize luminescent silicon nanoparticles on industrial glass fibers to impart optical and chemical functions to the fiber. Carpets or pads consisting of thousands of fibers are processed in parallel, enhancing the sensitivity of detection and the sampled volume. Treated pads exhibit strong luminescence, characteristic of the luminescence of the particles; showing no shift, broadening, or reduction of quantum efficiency. We demonstrate that drawing material by the pad due to physical adsorption can be reversed. We also demonstrate that allylamine can be covalently attached by photoinduced irradiation reactions, which results in imprinting the amine emission spectrum, providing spectral recognition. The imprint accompanied with a blue-shifting of the luminescence spectrum of the probe, allowing examination of the effect of termination on the nanoparticle structure. The shift is found to be consistent with an increase in the bandgap of the Si nanoparticle and is consistent with Quantum Monte Carlo calculations. In addition to sampling, the nano probe pad has the potential to enable a variety of biomedical applications through subsequent attachment. [ABSTRACT FROM AUTHOR]

Glass fibers with a diameter of 100–200 μm are drawn by just pulling up melts of 30BaO–15TiO2–55GeO2 glass, and transparent crystallized glass fibers consisting of nonlinear optical Ba2TiGe2O8 crystals are fabricated by crystallization of glass fibers. It is clarified from linearly polarized micro-Raman scattering spectra that fibers show the surface crystallization and Ba2TiGe2O8 crystals grow from the surface to the interior, giving c-axis orientations. It is found that holes are formed frequently in the center of fully crystallized glass fibers, and transparent hollow crystallized glass fibers are fabricated through careful heat treatments, e.g., fibers with [lowercase_phi_synonym]=200 μm show hollows (capillary-type holes) with [lowercase_phi_synonym]=40 μm. By adding a small amount of Sb2O3 in glass fiber preparations, transparent crystallized glass fibers with no holes are developed and second harmonic generations (SHGs) are clearly observed from such fibers. The present study proposes that transparent crystallized glass fibers showing strong SHGs would have a potential for fiber-type light control optical devices. [ABSTRACT FROM AUTHOR]

A refined model of a glass laser texturing process used on computer disk substrates is presented. Field equations for fictive temperature and elasto-viscoplastic strain in the glass are numerically integrated over the thermal cycle created with a microsecond CO[sub 2] laser pulse. Calculating the fictive temperature change as part of the solution provides for a consistent treatment of glass properties that depend on fictive temperature. The short time scale of the thermal cycle causes the final altered state of fictive temperature in the heat affected zone to be relatively constant over the depth of change, and higher than the initial value by more than 300 K. Plastic strain resulting from thermomechanical stresses and the fictive temperature rise are considered in this description. The model illustrates the rise in the compressive stress caused by initial heating, the relaxation process that occurs in the molten region above the transition temperature, and the subsequent introduction of tensile stress during cooling. At the end of the thermal cycle, the region of glass with altered fictive temperature is left in a state of high tensile stress. The time evolution of surface topography is studied with the model, and shows good agreement with measured dimensions of the final bump geometry over a range of laser pulse energies. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A flexible, hollow glass fiber is proposed as a delivery medium of femtosecond pulses. It was shown that ultrashort pulses with a pulse width of 196 fs, energy of 700 μJ, and repetition rate of 1 kHz are transmitted by the hollow fibers with no damage on the fiber. In the fiber with an inner diameter of 1 mm, the transmission loss is as low as 0.13 dB and the pulse broadening after transmission in 1 m long fiber is 17 fs. It is also shown that the numbers of transmitted modes in the fiber are estimated from the pulse broadening width. [ABSTRACT FROM AUTHOR]