Synthesis, optical and magnetic behavior of (BiFeO3)1−x(α-Fe2O3)x nanocomposites

(BiFeO3)1−x(α-Fe2O3)x nanocomposites were synthesized from dried gels of BiFeO3 and α-Fe2O3. Samples with x = (0.00 (BiFeO3), 0.25, 0.50 and 1.00 (α-Fe2O3)) were studied using X-rays diffractions (XRD), UV–vis spectroscopy, photoluminescence spectroscopy (PL), electron spin resonance (ESR) and vibrating sample magnetometer (VSM). Amounts of α-Fe2O3 phase were 23 and 35% for samples x = 0.25 and 0.50, respectively. Microstrain of BiFeO3 phase tended to decrease with increasing α-Fe2O3. Optical band gap reduced from 2.42 eV for BiFeO3 to 2.35 eV for sample x = 0.25 and then increased to 2.56 eV for sample x = 0.50. From PL, intensity of near band emission peak of BiFeO3 increased with increasing α-Fe2O3 content. From ESR and VSM, the g-value and magnetization saturation were enhanced with embedding of α-Fe2O3 into BiFeO3

Gain-clamped L-band EDFA using narrow and broadband fiber Bragg gratings for gain-flattened

In the wavelength division multiplexing (WDM) networks, the signal power in the link is varies with the changes in number of signals and link losses. A sudden signal added/dropped can caused the surviving signal have power transient (Desurvire, 1989; Sun et al., 1997) and when these signal is amplified by the erbium-doped fiber amplifier (EDFA), unequally signal power between channel became larger and causes an error detection at the receiver (Zhou et al., 2000). The increasing demand intended the networks provider to increasing link capacity. At maximum gain bandwidth of C and L band, a single fiber can carry 80 channels data (Scheerer et al., 1999) using gain-flattened EDFA has been reported

Synthesis, characterization and nonlinear optical properties of silver/PVA nanocomposites

Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10^-8. The nonlinear refractive index increases as amount of reducing agent increases

Temperature sensitivity comparison between bare FBG and buffered FBG

The work presented in this paper compares the temperature sensitivity between bare fiber Bragg grating (FBG) and acrylate buffered FBG. Both FBGs were subjected to temperature variation and their wavelength shifts were recorded. It has been found that buffered FBG is more sensitive than bare FBG due to the higher thermal expansion of the acrylate buffer. The wavelength shift of the FBG increased linearly with the increment of temperature producing sensitivity of 0.0127nm/°C for buffered FBG while the sensitivity of bare FBG is measured at 0.01nm/°C. The findings emphasize the impact of the acrylate buffer coating in enhancing the FBG temperature sensitivity

Multiwavelength hybrid fiber raman/parametric linear oscillator

We demonstrate a linear cavity wideband multiwavelength fiber-based optical parametric oscillator consisting of four fiber Bragg gratings (FBGs). The FBGs center wavelengths are chosen such that they are 3.2 THz (26 nm) and 14.3 THz (115 nm) away from the parametric pump wavelength, with each located in the dominant region of parametric and Raman gain, respectively. Investigation shows that interplay between the lasing processes from the parametric and Raman gain region can be carefully adjusted to produce multiwavelength lasers spanning from 1436 to 1704 nm, with optical signal-to-noise ratio ranging from 14.3 to 54.0 dB

Effect of gold-nanoparticle size on microfiber saturable absorber for mode-locked erbium-doped fiber lasers

Effect of gold-nanoparticle size on microfiber saturable absorber for mode-locked erbium-doped fiber lasers The optical performance of passively mode-locked erbium-doped fiber laser incorporating gold-nanoparticles (Au-NPs) of different sizes as saturable absorbers (SAs) was compared. A composite of Au-NPs with polydimethylsiloxane was spin coated on the surface of a microfiber waveguide. The fabricated Au-NP-based SA was deployed in a ring cavity erbium-doped fiber laser and its lasing performance was evaluated by comparing SA characteristics as well as pulse qualities among the different Au-NP sizes. The optimum pulse performance was realized when the SA was fabricated with 20 and 40 nm Au-NP size. For the former, time-bandwidth product of 0.34 was demonstrated which was the closest to its bandwidth-limited pulse. As for the latter, the fabricated SA exhibited 4.0% modulation depth and an average pulse duration of 886.7 fs. The research work has demonstrated the functionality of Au-NPs as a saturable absorption material for ultrashort pulses generation. In addition, the influence of nanomaterial size towards the characteristics of saturable absorbers, ergo the quality of laser pulse, was verified. This finding is also valuable in customizing ultrashort pulse output that can effectively suit system performance need

Latest developments in silica-based thermoluminescence spectrometry and dosimetry

Using irradiated doped-silica preforms from which fibres for thermoluminescence dosimetry applications can be fabricated we have carried out a range of luminescence studies, the TL yield of the fibre systems offering many advantages over conventional passive dosimetry types. In this paper we investigate such media, showing emission spectra for irradiated preforms and the TL response of glass beads following irradiation to an Am-241-Be neutron source located in a tank of water, the glass fibres and beads offering the advantage of being able to be placed directly into liquid. The outcomes from these and other lines of research are intended to inform development of doped silica radiation dosimeters of versatile utility, extending from environmental evaluations through to clinical and industrial applications. (C) 2015 Elsevier Ltd. All rights reserve

Preparation and Characterization of GG-LiCF3SO3-DMSO Gel Polymer Electrolyte for Potential Lithium-Ion Battery Application

This work uses gellan gum (GG) natural polymer as the base polymer to prepare gel polymer electrolytes (GPEs). Lithium trifluoromethanesulfonate (LiCF3SO3) salt is used as a charge supplier, and dimethyl sulfoxide (DMSO) acts as a plasticizer to keep the electrolyte in gel form. Two electrolyte systems are formed, which are LiCF3SO3-DMSO liquid electrolytes and GG-LiCF3SO3-DMSO GPEs. Liquid electrolyte with a composition of 12.42 wt.% LiCF3SO3-87.58 wt.% DMSO (LN3 electrolyte) revealed the highest room temperature conductivity (σrt) of 9.14 mS cm-1. The highest σrt value obtained by the LN3 electrolyte is strongly influenced by the charge carrier concentration (n) relative to the mobility (µ). To form GPEs, GG is added to the LN3 electrolyte since this sample composition gave the highest σrt. The electrolyte of 2.00 wt.% GG-12.18 wt.% LiCF3SO3-85.82 wt.% DMSO (GN3 electrolyte) showed the highest σrt of 9.96 mS cm-1. The highest σrt value obtained by GN3 electrolyte is strongly influenced by µ rather than n. The conductivity-temperature study showed that the increase in conductivity for GG-LiCF3SO3-DMSO GPEs is controlled by an increase in n, not µ. Linear sweep voltammetry (LSV) for the GN3 electrolyte showed high electrochemical stability up to 4.8 V. Cyclic voltammetry (CV) illustrated the redox process in the GN3 electrolyte is reversible. A lithium-ion battery fabricated with GN3 electrolyte showed a good discharge performance up to 480 hours with an average voltage of 1.50 V discharged at a current of 0.001 mA. Based on this work, it can be concluded that natural polymer GG-based GPE has great potential for use in LIBs as a charge transport medium