The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Voicu Lupei - One of the best experts on this subject based on the ideXlab platform.
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Laser Materials: Relationship between Materials and Laser Properties
Reference Module in Materials Science and Materials Engineering, 2016Co-Authors: Voicu LupeiAbstract:Abstract The chapter discusses the determining role of the characteristics of the Laser material – composition, structure, optical, spectroscopic, mechanical, thermal properties – on the Laser emission properties. A large variety of solid-state Laser Materials, such as single crystals, polycrystalline Materials produced by ceramic techniques, and glasses doped with 3d- or 4f-elements as active ions is considered. It is inferred that the development and optimization of the solid-state Laser requires a correlated approach of the Laser design and pumping system to exploit the properties of the Laser material.
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Transparent polycrystalline ceramic Laser Materials
Optical Materials, 2008Co-Authors: Voicu Lupei, Aurelia Lupei, Akio IkesueAbstract:High-resolution spectroscopy of the rare earth ions in transparent ceramics of garnets and sesquioxides produced by solid-state synthesis indicate that the variety, nature and structure of the centers formed by the doping ions, their quantum states (energy levels, transition probabilities) and interionic interactions as well as the distribution of the doping ions at the available lattice sites is similar to those of the corresponding single crystals. Moreover, the increased compositional versatility of ceramics enables tailoring of new or improved Laser Materials. It is inferred that from spectroscopic point of view, the transparent polycrystalline ceramics can substitute the single crystal and extend their capabilities.
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Heat generation in the pumped Nd Laser Materials
2004Co-Authors: Voicu LupeiAbstract:The paper presents a modeling of heat generation by non-radiative de-excitation processes in pumped Laser Materials. This model explains consistently the differences in heat generation in Nd Laser Materials in presence and in absence of Laser emission and its dependence on the emission wavelength, on Laser extraction efficiency and on Nd concentration.
Akio Ikesue - One of the best experts on this subject based on the ideXlab platform.
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ceramic Laser Materials
Nature Photonics, 2008Co-Authors: Akio Ikesue, Yan Lin AungAbstract:The word 'ceramics' is derived from the Greek keramos, meaning pottery and porcelain. The opaque and translucent cement and clay often used in tableware are not appropriate for optical applications because of the high content of optical scattering sources, that is, defects. Recently, scientists have shown that by eliminating the defects, a new, refined ceramic material — polycrystalline ceramic — can be produced. This advanced ceramic material offers practical Laser generation and is anticipated to be a highly attractive alternative to conventional glass and single-crystal Laser technologies in the future. Here we review the history of the development of ceramic Lasers, the principle of Laser generation based on this material, some typical results achieved with ceramic Lasers so far, and discuss the potential future outlook for the field.
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three dimensional grain boundary spectroscopy in transparent high power ceramic Laser Materials
Optics Express, 2008Co-Authors: M O Ramirez, Akio Ikesue, Jeffrey Wisdom, Yan Lin Aung, J P Stitt, Gary L Messing, Volkmar Dierolf, Zhiwen Liu, R L Byer, Venkatraman GopalanAbstract:Using confocal Raman and fluorescence spectroscopic imaging in 3-dimensions, we show direct evidence of inhomogeneous Nd3+ distribution across grain boundaries (GBs) in Nd3+:YAG Laser ceramics. It is clearly shown that Nd3+ segregation takes place at GBs leading to self-fluorescence quenching which affects a volume fraction as high as 20%. In addition, we show a clear trend of increasing spatial inhomogeneities in Nd3+ concentration when the doping levels exceeds 3 at%, which is not detected by standard spectrometry techniques. These results could point the way to further improvements in what is already an impressive class of ceramic Laser Materials.
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three dimensional grain boundary spectroscopy in transparent high power ceramic Laser Materials
arXiv: Materials Science, 2008Co-Authors: M O Ramirez, Akio Ikesue, Jeffrey Wisdom, Yan Lin Aung, J P Stitt, Gary L Messing, Volkmar Dierolf, Zhiwen Liu, R L Byer, Venkatraman GopalanAbstract:Using confocal Raman and fluorescence spectroscopic imaging in 3-dimensions, we show direct evidence for Nd3+-Nd3+ interactions across grain boundaries (GBs) in Nd3+:YAG Laser ceramics. It is clearly shown that Nd3+ segregation takes place at GBs leading to self-fluorescence quenching which affects a volume fraction as high as 20%. In addition, we show a clear trend of increasing spatial inhomogeneities in Nd3+ concentration when the doping levels exceeds 3 at%, which is not detected by standard spectrometry techniques. These results could point the way to further improvements in what is already an impressive class of ceramic Laser Materials.
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Transparent polycrystalline ceramic Laser Materials
Optical Materials, 2008Co-Authors: Voicu Lupei, Aurelia Lupei, Akio IkesueAbstract:High-resolution spectroscopy of the rare earth ions in transparent ceramics of garnets and sesquioxides produced by solid-state synthesis indicate that the variety, nature and structure of the centers formed by the doping ions, their quantum states (energy levels, transition probabilities) and interionic interactions as well as the distribution of the doping ions at the available lattice sites is similar to those of the corresponding single crystals. Moreover, the increased compositional versatility of ceramics enables tailoring of new or improved Laser Materials. It is inferred that from spectroscopic point of view, the transparent polycrystalline ceramics can substitute the single crystal and extend their capabilities.
Takunori Taira - One of the best experts on this subject based on the ideXlab platform.
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temperature dependencies of stimulated emission cross section for nd doped solid state Laser Materials
Optical Materials Express, 2012Co-Authors: Yoichi Sato, Takunori TairaAbstract:Temperature dependencies of stimulated emission cross section for Nd:YAG, Nd:YVO4, and Nd:GdVO4 was carefully evaluated. Our spectral evaluations with fine spectral resolution were carried out under the condition that the population inversion was induced into samples by a weak pumping field. Within the temperature range from 15°C to 65°C, the variation of emission cross section at 1.06 μm in Nd:YAG was −0.20%/°C, while those in Nd:YVO4 and Nd:GdVO4 for π-polarization were −0.50%/°C and −0.48%/°C, respectively. Consideration of measured temperature dependence gave the numerical model for temperature dependent emission cross sections of Nd-doped solid-state Laser Materials. We have also presented numerical approximations of this model for our samples by a simple polynomial, which can be applicable within the temperature range from 15°C to 350°C.
Michael J. Cieslak - One of the best experts on this subject based on the ideXlab platform.
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Laser Materials processing at Sandia National Laboratories
Journal of Laser Applications, 1996Co-Authors: James L. Jellison, Michael J. CieslakAbstract:This paper describes the Laser Materials processing capabilities at Sandia National Laboratories. Some of the advances in the understanding of various aspects of Laser Materials processing which have been made by the Laser Materials processing team at Sandia are discussed.
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Laser Materials processing at Sandia National Laboratories
International Congress on Applications of Lasers & Electro-Optics, 1994Co-Authors: James L. Jellison, Michael J. CieslakAbstract:The interest in Laser processing has been driven by Sandia`s responsibility to design, prototype, manufacture, and steward high reliability defense hardware for the Department of Energy. The system requirements for the hardware generally necessitate hermetic sealing for ensured long life operation. With the advent of miniaturized electronic devices, traditional welding processes were no longer practical choices because of their limited ability to make very small weld closures without heat damage to the hardware. Gas and solid state Lasers offered the opportunity to make hermetic closure welds in small, heat sensitive hardware. In order to consistently produce quality product, the Sandia Laser Materials processing team performed research aimed at identifying those critical parameters which controlled the Laser welding process. This has been directed towards both the development of quantitative engineering data needed in product design and process control, and research to achieve fundamental process understanding. In addition, they have developed novel diagnostic systems to measure these important parameters, pioneered the use of calorimetric techniques to measure energy transfer efficiencies, and correlated the occurrence of welding defects with alloy compositions and type of Laser welding process. Today, Sandia`s Laser Materials processing team continues to advance the state of Laser processing technology inmore » many areas, including aluminum Laser welding, the design of novel optics for specific Laser processing needs, Laser micromachining of silicon and diamond for microelectronics applications, and fluxless Laser soldering. This paper will serve to highlight some examples of where Sandia has made contributions to the field of Laser Materials processing and will indicate the directions where they expect to focus their future efforts.« less
H.p. Weber - One of the best experts on this subject based on the ideXlab platform.
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Thermal effects in solid-state Laser Materials
Optical Materials, 1998Co-Authors: R. Weber, B. Neuenschwander, H.p. WeberAbstract:Thermal effects in solid-state Laser Materials are a critical issue for designing diode-pumped solid-state Lasers. An overview over temperature and stress distribution as well as their influence on the optical behavior is given. Basic analytical treatment of the rod geometry is compared with a more accurate Finite Element calculation for the case of a transversally diode-pumped Nd:YAG rod. Significant differences in the shape of the thermal lens are observed.
