Rares Medianu

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<title>High-efficiency high-optical-quality transverse-flow CO<formula><inf><roman>2</roman></inf></formula> laser</title>

XII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 1998

<title>Surface and bulk crystallization of some glasses from the BaO-TiO<formula><inf><roman>2</roman></inf></formula>-B<formula><inf><roman>2</roman></inf></formula>O<formula><inf><roman>3</roman></inf></formula> system</title>

<title>Characteristics of a carbon/nickel multilayer structure for soft x-ray optics deposited by rf magnetron sputtering</title>

ROMOPTO '97: Fifth Conference on Optics, 1998

Special mirrors for cw CO2 high-power lasers

Proceedings of Spie the International Society For Optical Engineering, Jul 1, 1998

`Special mirror' concept is presented as a `spare module' for a GaAs extracting mirror technologi... more `Special mirror' concept is presented as a `spare module' for a GaAs extracting mirror technological processed with GaAs thin films, mounted within two kinds of c.w. CO2 laser resonators: U-type resonator (with optical pathlength Lr equals 4 m) and U- type folded resonator with V-discharge on each branch, reversal mirror provided (with the optical pathlength Lr equals 8 m), experimentally used to obtain good quality laser beam. The extracting mirror presents variable reflectivity, acting as a super-Gaussian mirror and working as an output coupler in the resonator, providing total compensation of the refractive index and of the small gain asymmetries.

Oane Cover 2

Bioactive ceramic glasses in situ synthesized by laser melting

Proceedings of Spie the International Society For Optical Engineering, 2009

The synthesis of bioactive glass from raw materials even during the laser deposition process, cou... more

Differential thermal analyses used to obtain glass ceramics in which precipitated barium titanate and barium borate

Surface and bulk crystallization of some glasses from the BaO-TiO2B2O3 system

Proceedings of SPIE - The International Society for Optical Engineering

Dielectric and especially ferroelectric materials can be used in many applications such as dynami... more Dielectric and especially ferroelectric materials can be used in many applications such as dynamic random access memories and infrared sensors. The dielectric properties of such materials have to be improved. For this purpose several compositions in the BaO-B2O3-TiO2 system have been studied. The investigated composition was BaTiO3 with a different amount of B203 in the range 25 - 50 mol%. Depending on the B2O3 amount the melting temperatures of the investigated glasses were in the range 1100 - 1250°C. The vitreous materials have been submitted to thermal treatment in order to obtain surface and bulk crystallization. The Differential Thermal Analyses (DTA) showed out the tendency of crystallization for these samples in the 600 - 800°C-temperature range. For structural analyses there have been used the X-ray diffractometry. DTA analyses, electronic microscopy and atomic force microscopy on samples crystallized by controlled thermal treatments.

Radial Variable Reflectance Mirrors at 10.6 mum

Proceedings of SPIE - The International Society for Optical Engineering

<title>Thermal fields in multimode laser-metallic thin film interaction</title>

Advances in Thin Film Coatings for Optical Applications, 2004

In the present paper we are dealing with the thermal fields for laser-metallic thin film interact... more In the present paper we are dealing with the thermal fields for laser-metallic thin film interaction. We propose a simplified model which takes into account just one global heat equation instead of two couple heat equations. For the parameters which are the same order of magnitude we take into account just the thermal coefficients of the substrate. The idea of

The role of surface absorption coefficient in the thermal field of the laser–thin film interaction

Optics & Laser Technology, 2004

In the present paper we developed a model of laser-thin ÿlm interaction, in order to ÿnd the ther... more In the present paper we developed a model of laser-thin ÿlm interaction, in order to ÿnd the thermal ÿelds during laser irradiation. The approximation consists in the fact that k (the thermal conductivity) and (the thermal di usivity) are of the same order of magnitude for the substrate and thin ÿlm. In consequence we can consider that we have one solid sample with k and of the Si substrate. On the other hand we cannot say the same thing about . One can easily see that, Si Cu; Al; Ag; Au . In consequence we propose an absorption coe cient, as close as possible to reality. In the present paper, we then calculate the thermal ÿelds produced by the surface absorption. ?

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Physico-chemical Properties of CuInGa-ZnS Heterostructure Deposited

A heterostructure is realized by successive deposition of copper-indium-gallium (CuInGa target) a... more A heterostructure is realized by successive deposition of copper-indium-gallium (CuInGa target) and zinc sulphide (ZnS target) thin films onto polyamide (e.g. kapton) substrate, using the rf magnetron sputtering technique. From scanning electron microscopy and atomic force microscopy studies resulted that the heterostructure shows a porous morphology with roughness values of 300-350 nm. CuInGa film exhibits three crystalline phases: In, Cu 2 In and Cu 16 In 9 . Deposition of ZnS onto CuInGa induce a recrystallization process supported by the increase in sample crystallinity and the formation of new ZnInS 4 and Zn 2.54 In 2.31 S 6 phases. Future work on the influence of ZnS thickness on recrystallization process is necessary.

Optical field properties in micro- and nano-structures - art. no. 67851D

Proceedings of SPIE - The International Society for Optical Engineering

We present an envelope formalism describing nonlinear phenomena in photonic crystals by casting t... more We present an envelope formalism describing nonlinear phenomena in photonic crystals by casting the Maxwell equations as a linear Hermitian eigenvalue problem in close analogy with the Schroedinger equation of quantum mechanics. From this formulation, applied to one dimensional photonic crystal, comes a variety of useful properties, including the density of modes and second harmonic generation. The mutual control of radiation field and matter defined by the control of photon modes by nonlinear photonic crystals -mode shapes, dispersion relations, optical solitons- is a key technology for future photonic devices.

Lucica Boroica, I. Boroica, E. Rotiu, B. A. Sava, R. Medianu, C. Timus & D. Hülsenberg „Radio frequency magnetron sputtering deposition of borate and phosphate glass films” Int. Conference “Micro- to Nano-Photonics -ROMOPTO 2006”. 2006 Sibiu Romania publicat in SPIE 6785/2007. p.24-27

Proceedings of SPIE - The International Society for Optical Engineering

New analytical heat transfer model for weak laser-crystalline solids interaction

We propose a coherent mathematical model for laser processing of crystalline solids when the soli... more We propose a coherent mathematical model for laser processing of crystalline solids when the solid's temperature variation is small (up to 100 K-300 K). In fact, we treat the heat equations for two major cases fulfilling our condition: i) the sample's absorption coefficient is very small (e.g. ZnSe, GaAs,); and/or ii) the laser intensity is not very high. The condition of small temperature variations has two advantages: validates the assumption on thermal independence for optical and thermal parameters (such as thermal diffusivity, thermal conductivity, heat transfer coefficient and absorption coefficient) and the possibility to make use of the linear heat absorption coefficients hypothesis. We present a number of three theorems in order to help the experimentalists in their work in the field of thermal effects in laser-matter interaction.

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<title>Effects of layer-by-layer deposition on the structural and optical characteristics of thin films</title>

ROMOPTO 2009: Ninth Conference on Optics: Micro- to Nanophotonics II, 2009

ABSTRACT CuIn1-xGaxS2 (CIGS2) thin-films for solar cells were prepared by rf-magnetron sputtering... more ABSTRACT CuIn1-xGaxS2 (CIGS2) thin-films for solar cells were prepared by rf-magnetron sputtering and were deposited on glass substrate. These films were prepared using a stepwise process consisting of succesive deposition of CuInGa (d = 1500 nm) and ZnS (d = 200 nm) layers. Each layer was structurally characterized by X-ray diffraction and atomic force microscopy. The microstructural and optical properties of CIGS2 component films of the solar cell in comparison with those of ZnS and CuInGa films separately deposited onto glass substrates under the same conditions, were studied. Transmission spectra of our thin films are strongly influenced by deposition conditions and nature of the support material and they were recorded for each component film and CIGS2 solar cell. Thin films, rf magnetron sputtering, CIGS2 solar cell, Surface roughness, Optical pr

<title>Aging behavior of some IR coatings for 10.6 μm</title>

ROMOPTO '94: Fourth Conference in Optics, 1995

ABSTRACT Output optical components on GaAs substrates devoted to the industrial CO2 lasers, deliv... more ABSTRACT Output optical components on GaAs substrates devoted to the industrial CO2 lasers, delivering up to 1200 W c.w. power laser levels, were investigated as regards the aging behavior of the optical coatings. IR spectrometry and thermal runaway in passive regime offer information about the optical dielectric coatings evolution. A comparison between the two deposition methods: thermal evaporation in high vacuum and r.f. magnetron sputtering put into evidence better results for the last method as regards the aging behavior of specific dielectrics used in IR.

<title>Infrared optically active structure obtained by plasma-assisted deposition (PAD) of III-V and II-VI binary compound thin layers</title>

ROMOPTO '94: Fourth Conference in Optics, 1995

ABSTRACT A possible mechanism for the chemical interactions during the argon plasma assisted depo... more ABSTRACT A possible mechanism for the chemical interactions during the argon plasma assisted deposition of thin layers of AIIIBV and AIIBVI binary compounds is presented. The model is aimed to serve as a basis to guide the experimental conditions for the obtaining of reflective or anti-reflective stoichiometric films on different substrates used as laser optical components. The theoretical assumptions were found in a good agreement with the results of the structural and optical properties measurements in case of ZnS and GaAs deposition from polycrystalline targets on (100) oriented GaAs singlecrystalline substrates. X- ray diffractometry and scanning electronic microscopy as well as IR transmission techniques were used in this respect.

<title>Medium-power cw He-Se laser</title>

ROMOPTO '97: Fifth Conference on Optics, 1998

<title>Unusual behavior of an asymmetric concave-convex-table resonator</title>

ROMOPTO '94: Fourth Conference in Optics, 1995

ABSTRACT A concave-convex stable laser resonator dedicated to a better matching of the waist on l... more ABSTRACT A concave-convex stable laser resonator dedicated to a better matching of the waist on large capillaries was developed. Power of 633 nm laser line for different positions of convex mirror for a medium power He-Ne Brewster windows ended, 2 mm ID laser tube was measured. The curves we obtained present an unusual behavior.

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