Nonlinear optical characterization of phosphate glasses based on ZnO using the Z-scan technique

The nonlinear optical properties of a phosphate vitreous system [(ZnO)x − (MgO)30−x − (P2O5)70], where x = 8, 10, 15, 18, and 20 mol% synthesized through the melt-quenching technique have been investigated by using the Z-scan technique. In the experiment, a continuous-wave laser with a wavelength of 405 nm was utilized to determine the sign and value of the nonlinear refractive (NLR) index and the absorption coefficient with closed and opened apertures of the Z-scan setup. The NLR index was found to increase with the ZnO concentration in the glass samples by an order of 10−10 cm2centerdotW−1. The real and imaginary parts of the third-order nonlinear susceptibility were calculated by referring to the NLR index (n2) and absorption coefficient (β) of the samples. The value of the third-order nonlinear susceptibility was presented by nonlinear refractive or absorptive behavior of phosphate glasses for proper utilization in nonlinear optical devices. Based on the measurement, the positive sign of the NLR index shows a self-focusing phenomenon. The figures of merit for each sample were calculated to judge the potential of phosphate glasses for application in optical switching

Effects of MgO on dielectric properties and electrical conductivity of ternary zinc magnesium phosphate glasses.

Glasses with composition (ZnO)30(MgO)x(P2O5)70-x(ZnO)30(MgO)x(P2O5)70-x (x = 5, 8, 13, 18 and 20 mol%) have been successfully prepared by the melt-quenching technique. The dielectric permittivity (ε′ε′) and loss factor (ε″ε″) were measured in the frequency range of 0.01 Hz to 1 MHz and in the temperature range of 303 to 573 K. From the results, there is evidence of dipolar relaxation occurring between View the MathML source103–106Hz, while at low frequencies, the spectrum is dominated by dc conduction which was manifested by the 1/ω1/ω slope of the loss factor plot. The value of the relaxing frequency (ωpωp) plotted against 1/T1/T shows a single relaxation mechanism with an activation energy of 0.45 eV. The average value of the activation energy for dc conduction was much higher (1.25 eV) suggesting its diffusion movement had encountered more difficult steps than the small displacement changing dipoles. With increasing MgO concentration, the dielectric permittivity (ε′ε′), dc conductivity (σdcσdc) and dielectric strength (ΔεΔε) decrease and these were attributed to some of the magnesium ions participated in the glass-forming positions as well as modifiers. At lower temperatures, the complex permittivity plots present a skewed arc with center point lying below the real axis which is a non-Debye characteristic. The empirical data were sufficiently fitted by using the Harviliak–Negami equation. The temperature dependent of the parameter αα is discussed

Optical properties of ultraphosphate glasses containing mixed divalent zinc and magnesium ions

Ternary zinc magnesium ultraphosphate glasses corresponding to (ZnO)x(MgO)30−x(P2O5)70 were prepared by melt quenching technique in the range of 5 ⩽ x ⩽ 20 mol%. The optical absorption spectra of the glasses were measured at room temperature in the wavelength range between 190 and 1100 nm, and the refractive indices of the glasses were measured at room temperature at a wavelength of 632.8 nm. The optical absorption spectra indicated that the electronic transition was indirect and associated with the phonon-assisted transition. From the absorption spectra, the optical energy band gap (Eopt) and Urbach energy (EU) values for all of the glass samples were calculated from their ultraviolet edges. The values of Eopt and EU were found to be in the range of 3.54–3.81 eV and 0.27–0.45 eV, respectively, both of which vary in a non-linear manner, with a turning point at 15 mol% of ZnO. The composition-dependence of these values has been suggested and analyzed in the light of switching role of Mg2+ based on its anomalous natural behavior from network builder to modifier depending upon its concentration. The values of refractive index ranged from 1.513 to 1.534. Variations in these optical parameters, as well as variations in density and molar volume are discussed and correlated with the structural changes within the glassy matrix

The design model of solar powered automatic bell system integrated with smoke detection for educational institution application

The work presents a design model of renewable energy based automatic bell system integrated with smoke detection, which uses solar energy as main power source. This design model is highly recommended to be installed in schools and learning institution, particularly in rural area as the power supply is the main constraint. In this work, the design which incorporates of the bell system, smoke detection and LCD display are presented using design software and their function is initialized using a programming language. The system model is designed to trigger bell at prescribed interval hours during school sessions. On the other hand, the design also includes a smoke sensor integrated with the bell system which triggers the bell during fire break out. The results outcome of this system is discussed accordingly. This design model is expected to save costs and enhance efficiency in power utilization using renewable energy as the main source of energy. In addition, the safety feature of the smoke detector is expected to safeguard school or institution from losses and damages caused by fire outbreak

The structural study of the ternary zinc magnesium phosphate glass

Background: Glass in the system (ZnO)30(MgO)x(P2O5)100-x (where x = 5, 10, 15, 20 mol %) were prepared by melt quenching technique. The structure of these glass systems has been investigated using FTIR spectroscopy. Objective: The IR spectra of the investigated glasses have been studied in order to understand the characteristic frequency of the vibrational chemical bonds and revealed the network structures of the phosphate glass samples. Results: The results revealed that the absorption band observed in the IR spectra composed of Q2 and Q3 phosphate units in the network glass structure. Conclusion: This study suggests that the changes in the structural of the ternary zinc magnesium phosphate glass related to the addition of Mg cation which acts as network modifier

Comparative study between measurement and predictions using geometrical optics and uniform theory of diffraction for case of non-line-of-sight (NLOS) in indoor environment

This paper describes the investigation and comparison of the accuracy of a deterministic model for a WLAN system in the indoor environment. The measurement system consisted of a spectrum analyzer and a log-periodic antenna. Non-line-of-sight (NLOS) propagation (in furnished rooms) was investigated. All the measurement sites mentioned in this paper are located in the Division of Information Technology at Universiti Putra Malaysia. The furnished rooms mentioned above were a teaching laboratory and a computer laboratory. The measured path losses were compared with the results obtained using deterministic models, namely the geometrical optics model and the uniform theory of diffraction model with the aid of image theory. The predicted results showed good agreement with the measured data for the NLOS environment, with an absolute mean error that ranged between 1.61 and 3.07 dB

Dielectric properties of ternary (ZnO)30(MgO)x(P2o5)70-x (x =5, 8, 13) glasses

(ZnO)30(MgO)x(P2O5)70-x glasses of the composition x = 5, 8 and 13 mol % have been prepared by melt quenching technique. The dielectric permittivity (ε′) and loss factor (ε″) were measured in the frequency range from 0.01 Hz to 1 MHz and in the temperature range 303 to 573 . From the results there are evidence of dipolar relaxation occurring between 103 – 106 Hz while at low frequency the spectrum is dominated by dc conduction which manifested by the 1/ω slope of loss factor plot. Value of the relaxing frequency (ωp) plotted against 1/T shows one electrical transportation mechanism. The empirical data was sufficiently fitted by using Harviliak-Negami equation

Finite difference analysis of an open-ended, coaxial sensor made of semi- rigid coaxial cable for determination of moisture in Tenera oil palm fruit

In this paper, the use of the Finite Difference Method (FDM) is proposed to determine the reflection coefficient of an open-ended coaxial sensor for determining the moisture content of oil palm fruit. Semirigid open-ended coaxial sensor is used in conjunction with Vector Network Analyzer for reflection coefficient measurement of oil palm fruit. Moisture content in oil palm fruit determine optimum harvest time of oil palm fruit. Finite difference method is then used to simulate measured reflection coefficient due to different moisture contents in oil palm fruit at various stages of ripeness. The FDM results were found to be in good agreement with measured data when compared with the quasi-static and capacitance model. Overall, the mean errors in magnitude and phase for the FDM were 0.03 and 3.70°, respectively