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Tb 3Sc 2Al 3O 12 (TSAG) is a paramagnetic insulator which, in spite of its congruent nature and excellent magneto-optical properties as Faraday rotators for optical isolators (OIs), cannot be industrially produced. The reason is that its lattice structure is so stressed that single crystals easily crack upon cooling after growth or during the cutting process. By the incorporation of a small amount of Lu, it has been demonstrated that the stress in the structure can be effectively released, and, therefore, the crystal cracking can be avoided. This has enabled the substitution of standard Tb 3Ga 5O 12 (TGG), achieving better high-power performance and compacter OIs. In this study, the charge state and the lattice site location of Lu as well as Y dopants in TSAG are investigated by X-ray Absorption Near Edge Structure and Extended X-ray Absorption Fine Structure Analysis. Measurements on single crystal and powdered samples indicate that both dopants are incorporated in the 3+ charge state and substitute predominantly in the dodecahedral Tb-site ( >87.5%), while a minor fraction is found in the octahedral Sc-site.

BaMgF4 single crystals doped with Nd3+ are of great interest as possible active media for VUV–UV and mid-IR all solid-state lasers. The luminescence spectroscopy and the excited state dynamics of these crystals are investigated for the first time upon VUV excitation using synchrotron radiation. The material shows fast Nd3+ 5d–4f emission upon direct VUV excitation into Nd3+ 5d levels. The decay kinetics of the Nd3+ 5d–4f emission in this host lattice upon direct VUV excitation of 5d levels is characterized by a lifetime of about 14 ns with no significant rise after the excitation pulse. No significant temperature dependence of the lifetime is observed within the range 8–300 K.

The following article appeared in Journal of Applied Physics 110.12 (2011): 123527 and may be found at http://scitation.aip.org/content/aip/journal/jap/110/12/10.1063/1.3671406, The energy transfer processes between Tb3 and Yb3 ions are studied in Tb-based fluoride single crystals. These are very transparent from the UV to the IR wavelength regions, except for the characteristic absorption lines of the rare-earth ions under study. In contrast with previously reported Tb 3-doped glasses and oxide powders, these crystals containing a high Tb3 concentration present two major advantages for the study of the energy transfer processes in the Tb3-Yb3 ion pair. Firstly, the adverse influence of host defects is minimized with the use of high quality crystals. Secondly, the high Tb 3 concentration guarantees a much higher absorption cross-section of UV light, and consequently these crystals have real potential for practical applications. Photoluminescence spectra in the visible-IR wavelength region demonstrate the existence of efficient down and up conversion processes by crossed excitation and emission characteristics of Tb3 and Yb3 ions. In the down conversion process, Tb3( 5D 4) → 2Yb 3( 2F 5/2), two IR photons are emitted for each Tb3 ion deexcited by second-order energy transfer to two Yb3 ions. The total quantum efficiency of the down conversion process in the fluoride system is shown to increase linearly with the Yb3 concentration, reaching its maximum at the Yb3 solubility limit in the fluoride host. Further, efficient up conversion by two- and three-IR photon absorption is observed., This work has been partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (C), 22560316, 2010.

International audience; Cd1−xMnxTe (x=0.1, 0.3, 0.5, 0.7 and 0.9) (CMT) single crystals were grown by the vertical Bridgman method. The optical studies reveal that with the increase in Mn concentration, the band gap values increase, which is attributed to s, p-d exchange interaction between the band carriers and Mn ions. Faraday rotation angle of the grown CMT (x=0.5) crystals were measured at the following wavelengths: 825, 1060 and 1575 nm. It was inferred that CMT exhibit larger Faraday effect (3-6 times larger than terbium-gallium garnet (TGG) currently used for optical isolators) making it as an efficient material for optical isolator at longer wavelengths. Field-cooled and zero field-cooled magnetizations of CMT were measured as a function of temperature and magnetic field. The spin-glass like behavior of CMT and their tendency to decrease in magnitude with increasing Mn concentration have been analyzed. The metal contacts on the Cd1−xMnxTe (x=0.1, 0.5, 0.7 and 0.9) crystals have been made with various metals and metal alloys to establish the ohmic contact. The detector characteristics of CMT have been tested using γ-rays with 511 keV (22 Na) and 59.5 keV (241 Am).

International audience; {Tb3}[Sc2−xLux](Al3)O12 crystals have been grown and investigated for the first time for magneto-optical applications. Tb3Al5O12 exhibits the best magneto-optical features; however, its incongruent melting nature has led to the industrial use of Tb3Ga5O12. Tb3Sc2Al3O12 had been proposed as an alternative to Tb3Al5O12, but unfortunately its growth also presents several drawbacks. The present investigation shows that by the isovalent substitution of Sc3+ by Lu3+ in the octahedral site of the garnet structure, it is possible to improve the growth characteristics while preserving the superior magneto-optical properties. We demonstrate that {Tb3}[Sc2−xLux](Al3)O12 crystals show a higher visible transparency and a larger Faraday rotation than Tb3Ga5O12 crystals. {Tb3}[Sc2−xLux](Al3)O12 is therefore a very promising material in particular for new magneto-optical applications in the visible-near IR wavelength region.