JFAS_Vol 04 N 01
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Item New Erbium Doped Antimony Glasses For Laser And Glass Amplification(University of Eloued جامعة الوادي, 2012-01-01) Tioua, B.; Soltani, M. T.; Hamzaoui, M.; Baazouzi, M.Because of the special spectroscopic properties of the rare earth ions, rare earth doped glasses are widely used in bulk and fiber lasers or amplifiers. The modelling of lasers and searching for new laser transitions require a precise knowledge of the spectroscopic properties of rare earth ions in different host glasses. In this poster will offer new doped erbium glasses synthesized in silicate crucibles were obtained in the combination Sb2O3-WO3-Na2O. Several properties are measured and correlated with glass compositions. The absorption spectral studies have been performed for erbium doped glasses. The intensities of various absorption bands of the doped glasses are measured and the Judd-Ofelt parameters have been computed. From the theory of Judd-Ofelt, various radiative properties, such as transition probability, branching ratio and radiative life time for various emission levels of these doped glasses have been determined and reported. These results confirm the ability of antimony glasses for glass amplification.Item Modelling Of Extrinsic Fiber Optic Sagnac Ultrasound Interferometer Used For Displacement Measurements(University of Eloued جامعة الوادي, 2012-01-01) Benhamida, S.; Rehouma, F.Ultrasonic waves are used extensively in nondestructive testing both for characterization of material properties, in this paper, we describe a fiber optic sensor suitable for detection of ultrasonic waves. This sensor is based on an extrinsic fiber optic sagnac interferometer. The proposed sensor model can act as a conventional in-phase detector or as a narrowband detector. In this study we use methods interference of ultrasonic waves between the source of ultrasonic waves and the object under investigation is exploited. The main advantages of the proposed sensor are the ability to detect ultrasonic waves on the surface; this sensor possesses higher sensitivity and accuracy than the pulse method. The cavity resonator was very successfully used for measurement of small ultrasound velocity changes. The ultrasonic interferometric technique based on phase-locked loop is the most suitable for measurements of small displacements. This method ensures the highest sensitivity and accuracy.Item Developement Of A Light Attenuator Based On Glassy Reflections(University of Eloued جامعة الوادي, 2012-01-01) Ferria, K.; Belkhir, N.The light intensity control of a luminous source is a very important operation in many optical applications. Several types of light attenuator exploiting different optical phenomena like diffraction, absorption, and reflection exist and they differ principally in the maximum attenuation rate, the control range, the sensitivity and the spectral band. In the presented work, we have developed and designed a light attenuator based on the progressive decrease of the transmitted light intensity, when it undergoes multiple vitreous reflections across eight plates glasses arranged in a roof shape. Several tests were carried out using a laser light as a source. We have shown that the attenuation rate can be controlled by the choice of the incidence angle on the glasses slides, in addition we have confirmed, for the case of perpendicular polarization of the laser light, that the attenuation obeys to a linear function. The obtained results are very close to those predicted theoretically.Item Spectroscopic Proprieties Of Crystals Mf2 (m=cd, Sr, Ba) Doped To Rare Earth Ions(University of Eloued جامعة الوادي, 2012-01-01) Diaf, M.; Khiari, S.; Labbaci, K.; Guerbous, L.; Jouart, J. P.In the present work, we are interested by studying the spectroscopic properties for optical applications, mainly laser amplification, of MF2 crystals, where M is an alkaline earth (Ba, Sr) or Cadmium (Cd) doped with rare earth ions (Tb3+, Er3+, Ho3+). So far, we present the absorption and emission properties and also the fluorescence dynamics at room temperature of visible and near infrared transitions of the Er3+ ion doping these matrices. We also use the formalism of Judd-Ofelt by use of absorption spectra recorded at room temperature in order to identify the spectroscopic properties inherent in all radiative transitions which can occur.Item Analysis Of Indexed-guided Highly Birefringent Photonic Crystal Fiber Employing Different Cladding Geometries(University of Eloued جامعة الوادي, 2012-01-01) Jouri, A. M.; Simohamed, L. M.; Boudrioua, A.; Ziane, O.; Hassani, B.; Dadi, A.In this paper, a comparative study of three geometries of highly birefringent photonic crystal fibers (HB PCF) is presented. The proposed geometries are: V type PCF, Pseudo-Panda PCF and selectively liquid-filled PCF. Based on the famous Finite Difference Time Domain (FDTD) method with the perfectly matched layer (PML) boundary condition, the simulations are carried out in the aim to find a tradeoff between the chromatic dispersion, the birefringence and the confinement loss.Item Gap In A Laser Frequency He-ne At 632.8 Nm(University of Eloued جامعة الوادي, 2012-01-01) Aissani, A.; Alliche, M.; Chaalal, M.; Ziane, O.The aim of this work is to show that the emitted signals of a double-output laser cavity exhibit distinctive features, manifesting themselves through typical dissymmetry in the corresponding spectral line shapes. Usually, such a dissymmetry in an inhomogeneously broadened gas laser appears with a clear but unpredictable shift of the maximum intensity level either towards the high or towards the low frequency sides with respect to line centre. In the case of a double-output laser, the spectral profiles show opposite shifts. This means that when the maximum intensity of one output moves towards the high frequency side of the profile, the maximum intensity of the other moves towards the low frequency side. This gives rise to a frequency shift, with respect to the Lamb-dip for a classical laser On the theoretical side, we apply the standard disturbed Gaussian beam model to give a good quantification of the frequency shifts obtained at both sides of the system.Item Brillouin Instability In Fiber Lasers Doped By Power(University of Eloued جامعة الوادي, 2012-01-01) Bouras, D. M.; Kellou, A.; Leblond, H.; Sanchez, F.With the emergence of rare-earth doped fibers, and especially double-clad fibers, there is a renewed interest in Brillouin effect. First of all, the amplification of a continuous signal in a rare-earth doped fiber amplifier can generate high enough intensities to excite Brillouin effect and then to create a backscattered stokes wave. Such back-reflection is detrimental for amplifier applications and consequently it has been studied theoretically and experimentally. Recently, the low frequency self-pulsing instability resulting from Brillouin backscattering has been theoretically modelled [1]. Our main objective is to present a general model allowing to explain the origin of the dynamic instability arising in a fiber lasers as a consequence of Brillouin effect. The effect of Brillouin back scattering is theoretically analysed by two-coupled modes laser model. We consider the Fabry-Perot fiber laser cavity. The rich and complex dynamic behaviours are observed. In particular the quasi periodic dynamic is identified and studied.Item Plasma-oxygen Interaction During Thin Films Deposition By Laser Ablation: Determination Of The Interaction Pressure Threshold And Effect On The Thin Films Propertiese(University of Eloued جامعة الوادي, 2012-01-01) Lafane S. . . . .; Kerdja T.; Abdelli-messaci S.; Khereddine Y.; Kechouane M.In this contribution we study the effect of the oxygen pressure on the plasma dynamics during the ablation of oxides materials into an oxygen gas. The study was done using fast imaging and ion probe techniques. Both techniques revealed that a threshold oxygen pressure is needed to initiate the plume oxygen interaction. This threshold oxygen pressure depends on the ablated material. A clear effect of this threshold pressure on the structural and phase composition of the deposited thin films is shown.Item Calculation Of Ionization Rate Coefficients Of Helium-like Iron(University of Eloued جامعة الوادي, 2012-01-01) Dilmi, S.; Guedda, E. H.The atomic data of the various atomic processes are essential for the radiative collisional models describing the plasmas. In this work we present our computation results of the ionization rate coefficients of helium-like iron ions. These types of ions can exist in all the types of plasmas. We use a simple numerical method to generate the ionization rates starting from the cross sections which are obtained by FAC (Flexible Atomic Code). Our computation results will be compared with those publisheItem Application Of Judd-ofelt Theory Upon Chlofluorophosphate Glass Doped With Erbium(University of Eloued جامعة الوادي, 2012-01-01) Babai, A.; Aiadi, K. E.; Bentouila, O.; Rehoma, F.; Poulain, M.A series of erbium doped glasses chlorofluorophosphates were prepared and characterized. The absorption spectra were analyzed to determine the Judd-Ofelt parameters. The optical performance of these doped glasses suggesting the relevance of these glasses for optical fiber/ wave guide lasers and optical amplifiers.Item Study Of The Propagation Of Short Pulse Laser With Cavity Using Numerical Simulation Software(University of Eloued جامعة الوادي, 2012-01-01) Terniche, S.; Kellou, A.; Kermaoui, A.; Si Fodil, R.; Becheker, R.The purpose of this representation is to show the potentialities (Computational Time, access to the dynamic and feasibility of systematic studies) of the numerical study of the nonlinear dynamics in laser cavity, assisted by software. We will give as an example, one type of cavity completely fibered composed of several elements and then studying the physical parameters of a pulse propagating into this cavity, determining its characteristics at the output. The results are interesting but we also projects to verify them experimentally by making assemblies similar to this type of cavities.Item Modeling Of The Thermal Behavior Of Metals During Welding Laser Using Beam(University of Eloued جامعة الوادي, 2012-01-01) Lemkeddem, S.; Khelfaoui, F.The laser welding provides a very high energy density, this allows the use of welds narrow, deep and at high speeds. Because of its advantages over other joining processes, laser welding is a process of manufacturing the most important. In order to model the thermal behavior, we must study the different phenomena that may be involved in the operation. The temperature distribution in the workpiece can be determined from the heat equation which expresses the energy balance. This is a parabolic differential equation and for resolution we applied the finite difference method using the implicit scheme.Item Analytical Expression For The Electric Field Of The Single Mode Laser Homogeneous Broadening In The Pulse Regime(University of Eloued جامعة الوادي, 2012-01-01) Ayadi, S.The simplest model of the laser is that of a single mode system homogenously broadened. The dynamical behavior of this laser is described by three differential equations, called Haken-Lorenz equations[1], similar to the Lorenz model [1] already known to predict deterministic chaos. In previous recent work [5-7] we have proposed a simple harmonic expansion method to obtain a series of harmonics terms that yield analytical solutions to the laser equations. This method allows us to derive an analytical expression of the laser field amplitude when this last undergoes a periodic oscillations around zero mean value. We also obtain an analytical expression of the pulsing frequency.Item Effect Of The Bit Rate On The Pulses Of The Laser Diodes(University of Eloued جامعة الوادي, 2012-01-01) Ikhlef, A.; Chikh-bled, M.The qualities required for Laser Diodes are their spatial and temporal coherence, and their performance in terms modulation. This paper presents the effect data rate of optical pulses delivered by diode laser using software COMSIS. Two types of modulation have been considered: direct modulation and external modulation.Item Study Of Polymorphism Of Borovanadate Glass Of Sodium By Raman Spectroscopy Low Frequencies(University of Eloued جامعة الوادي, 2012-01-01) Rabia, M. K.; Mayoufi, M.; Grosvalet, L.; Champagnon, B.Sodium tetraborate (100 – x)(Na2B4O7.10H2O)¬¬ ¬¬¬¬¬– xV2O5, (x = 0 to 20 mole %) has been elaborated by splat cooling technique. Raman Measurements on the doped and non polish samples reveal the presence of the of α-NaVO3 crystal on the superficial layer. After polishing, Raman spectra characteristic of glasses are obtained with two main bands located at 555 and 1097 cm-1 in the undoped glass and four bands at 241, 381, 776 and 938 cm-1 for the vanadium oxyde doped glasses. The volume devitrification of these glasses occurs at 750° C and the β-NaVO3 crystalline phase is identified by Raman scattering.