Composite Ceramic Lasers

In crystal composites, there is no chemical bond between the two crystals at the interface, which leads to low mechanical strength, low thermal conductivity, and poor thermal diffusivity. Therefore, such crystal composites cannot be used for high-power lasers, because the defects at the interface will absorb thermal energy, thus leading to decrease in beam quality and lasing efficiency. Due to potential 

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A similar strategy has been used to develop multilayered YAG-Yb YAG ceramics [317]. The layered stmctures with a tailored modulation of the doping level could facilitate to reduce the peak temperature, the temperature gradients, and 

44 SEM images of the Yb YAG composite ceramics a surface and b cross-sectional views. Reproduced with permission from [68]. Copyright 2012, Elsevier 

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A colloidal cocasting process was reported to fabricate multi-segment composite ceramic laser gain materials [319]. The three-segment transparent composite rod of 62 mm long and 3 mm diameter consisted of undoped YAG, 0.25 % Er YAG, and... 

In summary, the advanced ceramic composite technology has offered more opportunity to fabricate complex structures of composite ceramic lasers, due to the availability of perfect inherent interface characteristics. It is expected that this technology wiU be a key subject of research and development of solid-state ceramic lasers. 

Tang F, Cao YG, Huang JQ, Guo W, Liu HG, Wang WC et al (2012) Diode- pumped multilayer Yb YAG composite ceramic laser. Laser Phys Lett 9 564—569... 

Which of these techniques are most likely, in my estimation, to be applicable to ceramic matrix composites Ultrasonics or acoustic emission evaluation techniques are adaptable for high temperatures if high temperature coupling materials can be used. The other techniques do not appear to be immediately applicable, even to monolithic ceramics. Laser holography has been shown to be useful in determining displacements and deflections in turbine airfoils.28 For experimental laboratory setups, the use of such equipment is relatively direct but the most likely drawback for in-service conditions is the size and placement of lasers and detectors compared to the available space and design. Some creative engineering will be required here in order to utilize these kinds of techniques. 

Similar to most advanced engineering materials, transparent ceramic laser materials also have various requirements for practical appUcations. The fabrication and processing process should be reliable, consistent, feasible, reproducible, energy saving, cost-effective, and scalable. More importantly, the compositions, both the main components and the dopants, must be under good control. 

Applications of transparent ceramics are covered in the last two chapters, with Chap. 9 focusing on solid-state lasers with transparent ceramics and Chap. 10 on all other applications of transparent ceramics. In Chap. 9, besides traditional transparent laser ceramics, advanced ceramic laser technologies, including composite ceramics and crystal fibers (not ceramics), are also included, in order to demonstrate new research and development direction of solid-state lasers. In Chap. 10, other applications, such as lighting, scintillation, armor, potential biomaterials, and so on, are summarized and discussed. 

With a front face-pumped compact active-mirror laser (CAMIL) structure, an Yb YAGAY AG composite ceramic disk laser with pumping wavelength at 970 run has been reported [210]. The laser was operated in both CW and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2 % transmission OC was achieved at the wavelength of 1031 nm. Q-switched laser output was obtained by using an acousto-optic Q-switch, with repetition rates of 1-30 kHz and pulse widths of 166-700 ns. 

Fig. 9.51 Laser output as a function of absorbed pump power (quasi-CW) of the 62-mm (undoped YAG, 0.25 % EriYAG, and 0.5 % Er YAG) composite ceramic rod and the 45-mm (0.5 % Er YAG) single-crystalline reference laser rod, with slope efficiencies being calculated from the dashed lines. Reproduced with permission from [319]. Copyright 2010, Cambridge Univtrsity Press...

Ma J, Dong J, Ki Ueda, Kaminskii AA (2011) Optimization of Yb YAG/Cr YAG composite ceramics passively Q-switched microchip lasers. Appl Phys B Lasers Opt 105 749-760... 

Puruse H, Kawanaka J, Miyanaga N, Saiki T, Imasaki K, Fujita M et al (2011) Zig-zag active-mirror laser with cryogenic Yb YAGA AG composite ceramics. Opt Express 19 2448-2455... 

Ter-Gabrielyan N, Merkle LD, Kupp ER, Messing GL, Dubinskii M (2010) Efficient resonantiy pumped tape cast composite ceramic Er YAG laser at 1645 nm. Opt Lett 35 922-924... 

Cai H, Zhou J, Zhao HM, Qi YF, Lou QH, Dong JX et al (2008) Continuous-wave and Q-switched performance of an Yb YAG/YAG composite thin disk ceramic laser pumped with 970-nm laser diode. Chin Opt Lett 6 852-854... 

Electrical and Electronic Applications. Silver neodecanoate [62804-19-7] has been used in the preparation of a capacitor-end termination composition (110), lead and stannous neodecanoate have been used in circuit-board fabrication (111), and stannous neodecanoate has been used to form patterned semiconductive tin oxide films (112). The silver salt has also been used in the preparation of ceramic superconductors (113). Neodecanoate salts of barium, copper, yttrium, and europium have been used to prepare superconducting films and patterned thin-fHm superconductors. To prepare these materials, the metal salts are deposited on a substrate, then decomposed by heat to give the thin film (114—116) or by a focused beam (electron, ion, or laser) to give the patterned thin film (117,118). The resulting films exhibit superconductivity above Hquid nitrogen temperatures. 

The technique is referred to by several acronyms including LAMMA (Laser Microprobe Mass Analysis), LIMA (Laser Ionisation Mass Analysis), and LIMS (Laser Ionisation Mass Spectrometry). It provides a sensitive elemental and/or molecular detection capability which can be used for materials such as semiconductor devices, integrated optical components, alloys, ceramic composites as well as biological materials. The unique microanalytical capabilities that the technique provides in comparison with SIMS, AES and EPMA are that it provides a rapid, sensitive, elemental survey microanalysis, that it is able to analyse electrically insulating materials and that it has the potential for providing molecular or chemical bonding information from the analytical volume. 

There are numerous materials, both metallic and ceramic, that are produced via CVD processes, including some exciting new applications such as CVD diamond, but they all involve deposition on some substrate, making them fundamentally composite materials. There are equally numerous modifications to the basic CVD processes, leading to such exotic-sounding processes as vapor-phase epitaxy (VPE), atomic-layer epitaxy (ALE), chemical-beam epitaxy (CBE), plasma-enhanced CVD (PECVD), laser-assisted CVD (LACVD), and metal-organic compound CVD (MOCVD). We will discuss the specifics of CVD processing equipment and more CVD materials in Chapter 7. 

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