QUANTITATIVE-ANALYSIS

Transparent ceramics are important optical materials with applications in street lighting, high-strength windows, electro-and magneto-optical isolators, high-power laser gain media and radiation detectors. Their fabrication most often relies on powder densification techniques carried out at high temperatures, sometimes promoted by sintering additives. Here, we describe the application of laser-induced breakdown spectroscopy (LIBS) for following the concentration levels of silica used as a sintering agent in the fabrication of yttrium aluminum garnet (YAG) transparent ceramics. The sensitivity limit of our protocol reaches a few tens of ppm of silica in YAG ceramic samples, showing that LIBS can be implemented reliably for the rapid assessment of sintering additives in advanced ceramic processing. (C) 2017 Optical Society of America

BISMUTH TANTALATE CERAMICS; QUANTITATIVE-ANALYSIS; TRANSPARENT CERAMICS; OPTICAL-PROPERTIES; THIN-FILMS; MICROSTRUCTURE; FABRICATION; ABSORPTION

Strict control of composition is of paramount importance for the reproducible fabrication of advanced ceramics. In particular, the preparation of high-grade transparent ceramics of definite line-compounds requires that the ratio of major constitutive elements be quantified with a precision better than a fraction of a mole percent to prevent the precipitation of secondary phases and the scattering of light. Such a requirement poses difficult challenges to most analytical methods, especially when applied to nearly-stoichiometric insulating phases. In this work, we show that laser-induced breakdown spectroscopy (LIBS) is a well-suited technique for the assessment of non-stoichiometry in yttrium aluminum garnet (YAG) ceramics and that the aluminum to yttrium ratio can be determined with a resolution of 0.3 mol %, well within the phase boundaries of YAG. (C) 2017 Optical Society of America

GRADIENT-INDEX MICROLENSES; INTRAOCULAR LENSES; CONTACT-LENSES; POLY(METHYL METHACRYLATE); INDUCEDBREAKDOWN; FUSED-SILICA; WAVE-GUIDES; IN-VIVO; POLYMERS; INTERFEROMETRY

We describe the treatment of new hydrogels with nine different chemical compositions by femtosecond laser writing. The phase change induced in the wavefront when passing through the written areas was measured in all of these materials. The induced phase change is negative, which is attributed to the higher presence of water in the written regions and confirmed via Raman spectroscopy. The largest induced change in a single layer at 100 mm/s was -3.69 waves at 543 nm. These results show a strong dependence of the phase change on the concentration of some components and their molar ratio. We propose that some components are essential for the nonlinear energy absorption (""dopants""), while other components (""quenchers"") are essential in redirecting the absorbed energy to cause chemical reactions that profoundly change the polymer structure. (C) 2017 Optical Society of America