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Nd-doped CaWO[sub 4] (CWO) and NaGd(WO[sub 4] )[sub 2] (NGWO) single crystals with good optical quality have been grown by the Czochralski technique. The neodymium distribution coefficient in these matrices is about 0.4 for CWO and close to unity for NGWO. Polarized absorption and emission spectra have been recorded at room temperature and used to calculate the absorption and stimulated emission cross-sections.1 and 2% Nd : CWO and 1% Nd:NGWO laser rods have been tested in a cavity longitudinaly pumped by an 1 W AIGaAs laser diode and compared to Nd : YAG and Nd : YVO[sub 4] rods in the same conditions. The 2% Nd : CWO rod exhibits the best performance with slope efficiencies of 64%, higher than in the case of YAG and equal to the YVO[sub 4] samples. The dependence of the laser output power versus the diode temperature has been measured for all these materials. The laser output of Nd : CWO was found to be nearly as stable as for Nd : YVO[sub 4] and much more stable than in the case of Nd : YAG. A CWO microchip has also been tested for the first time to our knowledge. [ABSTRACT FROM AUTHOR]

Abstract: We report on the epitaxial growth and spectroscopic study of highly doped Y2SiO5:Yb3+ (YSO:Yb) thin films on YSO substrates. The realization of Ge, La and Gd-codoped high quality thin films, with thickness up to 100μm, is demonstrated. YSO:Yb layers have their fluorescence and absorption spectra similar to the bulk ones, with a globally higher crystalline quality. The Yb3+ lifetime evolution exhibits a particularly slow decrease with Yb doping, proof of a low extrinsic quenching centers concentration. The refractive index increase with respect to dopants concentration is measured, and a phenomenological law is proposed. Such highly doped YSO:Yb layers could be an interesting alternative for active integrated optics or laser devices. [Copyright &y& Elsevier]

Abstract: Several CaF2 single crystals doped with trivalent rare-earth ions have been grown in the recent years in the form of bulk crystals by using the Bridgman method and in the form of thin films by using the MBE and LPE techniques. The spectroscopic, gain and laser properties of these crystals doped with Pr3+, on the one hand, and with Yb3+, Tm3+ or Er3+ ions, on the other hand, have been studied and are reviewed here for their laser potentials in the red and in the infrared spectral domains, respectively. [Copyright &y& Elsevier]

Abstract: We report on relative gain measurements at 1.92μm in Tm:CaF2 films grown on pure CaF2 substrates by using Liquid Phase Epitaxy with CaCl2 as a solvent. Electron microscopy and X-ray diffraction measurements show that the Tm3+:CaF2 films are about 5μm thick and have a small lattice mismatch with the CaF2 substrate. Room temperature emission spectra of the Tm3+ ions around 1.9μm exhibit the same structure as in the bulk crystals and the lifetime of the 3F4 metastable level is found equal to about 12.8ms. The Tm:CaF2 films are guiding optical waves and exhibit a relative gain of 7% at 1.92μm when pumped at 0.765μm. [Copyright &y& Elsevier]

The efficiency of high-resolution pixel detectors for hard X-rays is nowadays one of the major criteria which drives the feasibility of imaging experiments and in general the performance of an experimental station for synchrotron-based microtomography and radiography. Here the luminescent screen used for the indirect detection is focused on in order to increase the detective quantum efficiency: a novel scintillator based on doped Lu(2)SiO(5) (LSO), epitaxially grown as thin film via the liquid phase epitaxy technique. It is shown that, by using adapted growth and doping parameters as well as a dedicated substrate, the scintillation behaviour of a LSO-based thin crystal together with the high stopping power of the material allows for high-performance indirect X-ray detection. In detail, the conversion efficiency, the radioluminescence spectra, the optical absorption spectra under UV/visible-light and the afterglow are investigated. A set-up to study the effect of the thin-film scintillator's temperature on its conversion efficiency is described as well. It delivers knowledge which is important when working with higher photon flux densities and the corresponding high heat load on the material. Additionally, X-ray imaging systems based on different diffraction-limited visible-light optics and CCD cameras using among others LSO-based thin film are compared. Finally, the performance of the LSO thin film is illustrated by imaging a honey bee leg, demonstrating the value of efficient high-resolution computed tomography for life sciences.

We have studied Er3+, Yb3+, and Ce3+ codoped microchannel waveguides that were developed by two methods: ionic exchange for heavy metal fluoride glasses [ZrF4-BaF2-AlF3-CeF3 (ZBAC)] and vapor phase deposition for transition metal fluoride glasses [PbF2-ZnF2-GaF3 (PZG)] by using a double-pass technique. For the first time to our knowledge, the measurement of propagation losses and amplification tests were carried out by use of the same experimental setup, leading to complete characterization of the waveguides. Net gains higher than 1 dB/cm were achieved in ZBAC Er/Ce single-mode fluoride glass waveguides.