Numerical model of the temperature dependence of the up-conversion efficiency of fluoride crystals codoped with ytterbium and thulium

We review the role of temperature on the up-conversion efficiency of materials that are good candidates to be used as the three primary-color emitters in optically written displays. A rate equation model is given for the blue emitting material that includes temperature-dependent coefficients for energy transfer and cross relaxation. Increased temperature leads to decreased up-conversion efficiency. The effect of pumping conditions on heating the emitting material is illustrated and explained. Steps to reduce the temperature rise when pumping up-conversion materials are described

Investigation of diode-pumped 2.8-µm laser performance in Er:BaY2F8

Laser operation at 2.8 mm in BaY2F8 with erbium concentrations of 7.5% and 20% is investigated under laser-diode pumping at 967 nm. Output powers as high as 250 mW and slope efficiencies as high as 24% are obtained. Results are comparable with those of Er3+:LiYF4 under the same pump conditions. Slope efficiencies above 30% are predicted for optimized erbium concentrations

Thermal conductivity of single crystal lanthanum cuprates at very low temperature

We have undertaken a study of the thermal conductivity of single crystals of pure and strontium doped lanthanum copper oxide in the temperature range 0.1-6 K. For in plane conduction, all samples show approximately a T2.7 dependence, whereas for conduction across the planes for X = 0 we observe [kappa] ~ T2. This suggests that dimensionality may play an important role in the lattice heat conduction properties of these materials at very low temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29444/1/0000526.pd

New national curricula guidelines that support the use of interprofessional education in Brazilian context : an analysis of key documents

The National Curricular Guidelines (NCGs) are important documents for understanding the history of academic health professions education in Brazil. Key policies within the NCGs have helped to re-orient health professions education and have stimulated curricular changes, including active learning methodologies, more integrated teaching-service environments and, more recently, have introduced interprofessional education (IPE) in both undergraduate and postgraduate sectors. This paper presents the findings of a study that examined the NCGs for nursing, dentistry and medicine courses as juridical foundations for adopting strategies that promote IPE across higher education institutions in Brazil. We employed a comparative and exploratory documentary analysis to understand the role of IPE or collaborative practices in NCGs for the three largest professions in Brazil. Following a thematic analysis of these texts, four key themes emerged: faculty development; competencies for teamwork; curricular structure; and learning metrics. Key findings related to each of these themes are presented and discussed in relation to the wider interprofessional literature. The paper goes on to argue that the statements contained in the NCGs about adoption of IPE and collaborative practices will have an important influence in shaping the future of health professions education in Brazil

Spectroscopy And Dynamic Measurements Of A Tm,Dy : Bay2F8 Crystal

A Tm, Dy : BaY2F8 crystal is studied in order to develop a solid state laser device pumped by a diode laser. Spectroscopic results include the measurements of the absorption and fluorescence spectra of both Tm and Dy at various crystal temperatures. Moreover, we measured the lifetime and deduced the emission cross-section of the 6H13/2 → 6H15/2 Dy transition in the 3 μm wavelength region. We also calculated the radiative lifetime of the upper multiplet and estimated the phonon energy of the crystal. © 1999 Elsevier Science B.V. All rights reserved

Periodic absorption in monoclinic crystals

No abstract availabl

Kerr-Lens Mode-Locked Diode-Pumped Cr:Lisgaf Laser

We have demonstrated stable and self-sustaining Kerr-lens mode locking of a Cr:LiSGAF laser pumped by AlGaInP laser diodes. A hard aperture near one end of the laser provides the necessary amplitude modulation. This allsolid-state system generates transform-limited 100-fs pulses, tunable from 810 to 860 nm. The average power at 830 nm is 35 mW, with fluctuations of much less than 1%. The thermal properties of Cr:LiSGAF will permit scaling of these results to higher power. © 1995, Optical Society of America