FLASHLAMP PUMPED COLOUR CENTRE LASERS IN LiF AND NaF

We describe pulsed flashlamp pumped colour centres laser. The laser emission of F+2 centres in LiFOH- at 77K, F+2 centres in NaF at RT and (F+2)A centres in NaFLi at R.T

Luminescence properties of Cr2+:ZnSe: Comparison between a single crystal and a film deposited by RF magnetron co-sputtering

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Magnetic circular dichroism of colour centres in CaF2 : Na

The magnetic circular dichroism (M.C.D.) of several centres in additively coloured CaF2 : Na has been measured as a function of temperature in the 1.65-195 K range. The 612, 435 and 382-385 nm bands display significant paramagnetic M.C.D. signals, which proves that they most probably arise from centres with an odd number of electrons. Thus 612 nm cannot be only a transition of the [1, 0, 0] oriented F2A centre, as currently assumed. On the other hand, the 490 nm band only shows a diamagnetic M.C.D. We tentatively discuss some possible assignments for the chief absorption bands of colour centres in CaF2 : Na, but further work using complementary techniques is clearly necessary before one comes to a reliable conclusion

New optical transitions of colour centres in CaF2 : Na+

New colour centres are detected in CaF2 : Na+ by their absorption, emission and excitation optical spectra. The so-called f centre accounts for a fluorescence band peaking at 573 nm, an excitation band at 510 nm and a zero-phonon line at 541.8 nm. The so-called g centre has emission and excitation bands respectively centred at 681 and approximately 562 nm. A number of sharp lines appears in the absorption and fluorescence spectra, some of which are zero-phonon lines of known centres, or their vibrational satellites, while others are still unidentified.Nous mettons en évidence de nouveaux centres colorés dans CaF2 : Na+ par leurs spectres optiques d'absorption, d'émission et d'excitation. Le centre que nous appelons f est responsable d'une bande de fluorescence qui culmine à 573 nm, d'une bande d'excitation à 510 nm et d'une raie à zéro-phonon à 541,8 nm. Le centre que nous appelons g a des bandes d'émission et d'excitation respectivement centrées à 681 et à environ 562 nm. De nombreuses raies fines apparaissent dans les spectres d'absorption et de fluorescence; les unes sont des raies à zéro-phonon de centres connus, ou leurs satellites vibrationnels, tandis que les autres ne sont pas encore attribuées

Growth and luminescence study of Cr²⁺: ZnSe films deposited by radio-frequency magnetron co-sputtering

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Absorptions UV dans le fonctionnement des sources lasers solides à ions de terres rares

L'article donne une description et analyse les phénomènes d'absorption UV à l'origine des mécanismes de solarisation et de variation d'indice de réfraction observés dans certains matériaux dopés terres rares étudiés pour leurs propriétés laser UV ou infrarouge lorsqu'ils sont soumis à de fortes densités d'excitation optique

Excited-state absorption and fluorescence dynamics of Er3+Er^{3+}:KY3KY_{3}F10F_{10}

International audienceWe report here on a complete investigation of the excited-state absorption and fluorescence dynamics of $Er^{3+}$ doped $KY_{3}$$F_{10}$ single crystals versus dopant concentrations and optical excitation conditions. Radiative and effective (including non-radiative relaxations) emission lifetimes and branching ratios are determined from a Judd-Ofelt analysis of the absorption spectra and via specific fluorescence experiments using wavelength selective laser excitations. Excited-state absorption and emission spectra are registered within seven spectral domains, i.e. 560 nm, 650 nm, 710 nm, 810 nm, 970 nm, 1550 nm and 2750 nm. A maximum gain cross-section of 0.93 × $10^{−21}$ $cm^{2}$ is determined at the potential laser wavelength of 2.801 μm for a population ratio of 0.48. Saturation of fluorescence intensities and variations of population ratios versus pumping rates are registered and confronted with a rate equation model to derive the rates of the most important up-conversion and cross-relaxation energy transfers occurring at high dopant concentrations

Excited-state absorption and fluorescence dynamics in Er:CaF 2

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Spectroscopy and laser gain measurements of CaF2: Nd, X3+, Z3+ (X, Z = Gd, La, Ce, Y, Lu, Sc) crystals for broadband lasers applications

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Fonctionnement et potentialités des lasers LIYF4_4:Tm et KY3_3F10_{10}:Tm autour de 1,85 μ\mathsf{\mu}m

Des seuils et rendements laser très intéressants ont été obtenus récemment vers 1.9 $\mu$m avec deux cristaux LiYF$_4$ et KY$_3$F$_{10}$ dopés par l'ion Tm$^{3+}$ Différents types de fonctionnement (continu, accordable, déclenché passivement...) sont considérés