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1
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Synthesis and Characterization of Erbium Lithium Niobium Gallium Garnet

100%
Toma O., Gheorghe L., Vlaicu A.
Acta Physica Polonica A
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2012
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vol. 121
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issue 1
193-195
EN
The synthesis of a new garnet, Er_3Li_{0.275}Nb_{0.275}Ga_{4.45}O_{12} (ErLNGG), by solid-state reaction, is reported. A comparison of the fluorescence spectra of Er^{3+} in ErLNGG, Er-doped (0.1 at.%) calcium lithium niobium gallium garnet (CLNGG), and Er(50 at.%):CLNGG is presented. The narrowing of luminescence lines suggests an ordering of the partially disordered CLNGG with the increase of erbium concentration.
2
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Crystal Field Analysis of Cr^{3+} Energy Levels in LiGa_5O_8 Spinel

100%
Brik M., Avram N., Avram C.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
1055-1060
EN
Detailed and consistent crystal field analysis of the LiGa_5O_8:Cr^{3+} absorption spectrum is performed in the present paper by using the exchange charge model of crystal field. We calculate the crystal field parameters from the crystal structure date and diagonalize the crystal field Hamiltonian to obtain the energy level structure of Cr^{3+} ions in LiGa_5O_8. The obtained energy levels and estimated Racah parameters B and C were compared with the experimental spectroscopic data; good agreement was demonstrated.
3
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Optical Study of SrLaGaO_{4} and SrLaGa_{3}O_{7} Doped with Nd^{3+} and Yb^{3+}

100%
Ryba-Romanowski W., Gołąb S., Pisarski W., Dominiak-Dzik G., Gloubokov A.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
399-406
EN
Single crystals of SrLaGaO_{4} and SrLaGa_{3}O_{7} singly doped with Nd and codoped with Nd and Yb have been grown by the Czochralski method. Both the compounds form tetragonal crystals but belong to different space groups. A common feature of these matrices is a structural disorder resulting from statistical distribution of Sr^{2+} and La^{3+} ions over the lattice sites. A previous investigation of a laser diode pumped SrLaGa_{3}O_{7}:Nd laser revealed that inhomogeneous broadening of spectral lines of Nd^{3+} was advantageous for optical pumping and did not influence adversely the extraction efficiency. The present paper deals mainly with optical properties of Yb^{3+} ions which are of interest for the design of lasers pumped by a diode laser and operating near 1 μm.
4
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Growth of Oxide Laser Crystals by Czochralski Method

100%
Zharikov E., Lis D., Subbotin K., Dudnikova V., Zaitseva O.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
274-285
EN
The growth of series of actual laser crystals belonging to different structural types by the Czochralski method is presented. The primary attention is given to single crystalline compounds and their solid solutions with garnet structure (scandium-containing rare-earth garnets with general formula {LnSc}_3[ScMe]_2Me_3O_{12}, Me = Al, Ga) as well as with olivine (forsterite Mg_2SiO_4) and scheelite structure (double tungstates and molybdates with formula NaLn(TO_4)_2, where T = Mo or W). The broad bands of luminescence and absorption produced by activator ions in these laser hosts that appear either as a result of structural disorder (garnets, scheelites) or due to the doping by transition metal ions (chromium in forsterite) join together these representatives of different structural classes and determine their application in photonics. The paper considers the problems of growing of large crystals with uniform distribution of components and dopants, determination of congruently melting composition, especially in compounds with complex isomorphism. The mutual influence of components and dopants, redistribution of ions along crystallographically non-equivalent sites in the structure, alteration of valency of transition metal ions accompanied with the change of their segregation coefficients under variation of redox conditions is discussed.
5
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Influence of the γ-Radiation on the Generation Characteristics of the YAlO_{3}:Nd Crystals

100%
Sugak D., Matkovskii A., Grabovskii V., Prokhorenko V., Suchocki A., Durygin A., Solskii I., Shakhov A.
Acta Physica Polonica A
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1998
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vol. 93
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issue 4
643-648
EN
The results of investigation of the influence of γ-radiation by ^{60}Co-source on the YAlO_{3}:Nd laser generation characteristics are presented in this paper. The significant decrease in the output energy after γ-irradiation was obtained. The energetic characteristics are restored after illumination of the γ-irradiated laser rods by 1000-10000 pulses of the pumping lamp light. The additional absorption spectrum is induced by γ-irradiation in the crystals. The nature of the created in this way colour centres is discussed. The mechanism of influence of the colour centres on generation properties of the crystals is discussed.
6
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Investigation of As Grown and Induced Structural Defects in SrLaXO_{4} (x = Al, Ga) Crystals

100%
Ryba-Romanowski W., Gołąb S., Dereń P., Dominiak-Dzik G., Pisarski W., Gloubokov A.
Acta Physica Polonica A
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1997
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vol. 92
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issue 1
191-196
EN
SrLaGaO_{4} and SrLaAlO_{4} substrates grown by the Czochralski method have no twins or subgrains however they show strong tendency to form point defects. The nature of these defects is not well understood yet. They may be associated with deviations from stoichiometry andor oxygen atoms located in the interstitial positions. Virtually all title crystals grown by the Czochralski method display various colours from light green to deeply red owing to light absorption by point defects. Absorption centres appear to be very stable in time and resistant to usual thermal treatment. UV excitation increases the density of defects and gives rise to strong photoluminescence, otherwise too weak to be observed.
7
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Optical Methods in Characterization of HTSC Thin Film Substrates

100%
Ryba-Romanowski W.
Acta Physica Polonica A
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1997
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vol. 92
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issue 1
135-138
EN
Short overview of optical methods which proved to be useful in the characterization of HTSC thin film substrates is presented. Preliminary tests in polariscopic arrangements, interferometric measurements, optical absorption and emission spectroscopy reveal macroscopic deficiencies of the crystal. Intentionally introduced impurity ions serve as probes of a local strength and symmetry of the crystal field. Results of optical study of SrLaGaO_{4} and SrLaAlO_{4} crystals are presented and discussed.
8
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Czochralski Growth and Optical Properties οf (Lu_{x}Gd_{1-x})_2SiO_5 Solid Solution Crystals Single Doped with Sm^{3+} and~Dy^{3+}

80%
Ryba-Romanowski W., Strzęp A., Głowacki M., Lisiecki R., Solarz P., Domagala J.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
321-328
EN
Solid solution crystals (Lu_{x}Gd_{1-x})_2SiO_5 single doped with Sm^{3+} and Dy^{3+} were grown by the Czochralski method. Segregation coefficients Lu/Gd, melting temperatures and structures of solid solution crystals were determined for 0.15 ≤ x ≤ 0.8. It was found that for x ≥ 0.17 the crystals belong to the monoclinic system within a space group C2/c and their melting temperature diminishes monotonously from 1990C to 1780C when x decreases from 0.8 to 0.15. Disparity of ionic radii of Lu^{3+} and Gd^{3+} induces structural disorder that brings about an inhomogeneous broadening of spectral lines in absorption and emission spectra of incorporated luminescent Sm^{3+} and Dy^{3+} ions. Optical properties of obtained crystals were determined based on results of measurement of absorption and emission spectra and luminescence decay curves. Spectroscopic investigation revealed that Sm^{3+} doped crystals show intense emission distributed in the visible-near infrared region with the most intense band centred at 605 nm and characterized by a branching ratio of 0.43. Emission spectrum of Dy^{3+} doped crystals is dominated by a band centred at 575 nm and characterized by a branching ratio of 0.58. It has been concluded that the systems under study are potential laser materials able to generate visible emission upon GaN/InGaN laser diode pumping.
9
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Experimental and Theoretical Study of Zircon and Scheelite Phases of DyVO_4

80%
Ermakova O., Paszkowicz W., López-Solano J., Muñoz A., Dabkowska H.
Acta Physica Polonica A
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2012
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vol. 121
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issue 4
920-927
EN
Polycrystalline zircon-type dysprosium orthovanadate, DyVO_4, prepared from a single crystal grown by slow cooling from PbO/PbF_2 flux, was studied by X-ray diffraction. Rietveld refinement provided the following unit cell size and oxygen atom coordinates: a=7.14811(4) Å; c=6.30825(4) Å, V=322.323(3) Å3, y(O^{2-})=0.4300(4); z(O^{2-})=0.2082(4) which are of a particularly high accuracy and show consistency with earlier reported values. Density functional theory calculations within the generalized gradient approximation for the exchange-correlation energy were also performed, providing values of structure parameters which differ by less than 2% from the experimental ones. The agreement between theory and experiment demonstrates the value of these calculations for understanding the structure of compounds of RVO_4 family. In addition, density functional theory calculations were performed for the scheelite-type DyVO_4; also for this polymorph the discrepancy with the only known set of lattice parameters is less than 2%. Values of oxygen atom coordinates have not been reported yet for this polymorph; here, the calculated ones are quoted.
10
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Electron Spin Resonance Study of Nd^{3+} and Er^{3+} Ions in YAlO_{3}

80%
Jabłoński R., Frukacz Z.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
339-343
EN
In this paper we present the results of ESR and photo-ESR measurements on YAlO_{3}(YAP) single crystals and powder samples doped purposely with about 1 at.% Nd^{3+} and undoped crystals in which Er^{3+} was observed as residual dopant. The ESR measurements were carried out at X-band spectrometer in 4-300 K temperature range. The photo-ESR was performed at 5 K using a mercury arc lamp. For the Nd^{3+} doped crystals the intensity of ESR signal decreased about 2 times during illumination conditions. Moreover, the calculations of the g tensor and A hyperfine structure parameters for Nd^{3+} and Er^{3+} were carried out.
11
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Preparation and Characterization of Basic and Er^{3+}-Doped Glasses in the System Y_{2}O_{3}-Al_{2}O_{3}-ZrO_{2}

80%
Klement R., Hruška B., Hronský V., Olčák D.
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vol. 126
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issue 1
302-303
EN
The undoped, and Er-doped yttrium aluminozirconate (AYZ) glasses were prepared by flame synthesis in the form of transparent glass microbeads. The ZrO_{2} content was in the range between 5 and 20 mol. %. The prepared glass microbeads were characterised by optical microscopy, SEM, XRD, DSC, ^{27}Al MAS NMR, UV-VIS-NIR and fluorescence spectroscopy. The thermal stability of AYZ glasses, expressed in terms of the difference between the glass transition temperature, T_{g}, and the onset of crystallization, T_{x}, was not affected by the increasing ZrO_{2} content. The ^{27}Al MAS NMR spectra of studied glass samples reveal that Al atoms are predominantly 4-coordinated in glasses. The AYZ5 and AYZ10 basic glasses were doped with Er^{3+} at the level of 1-5 mol. % of Er_{2}O_{3}. The UV-VIS-NIR/fluorescence spectra show characteristic absorptions/emissions, due to the optically active Er^{3+} ions in the host glasses. The absorption/emission properties of guest ions are not significantly affected by the glass host.
12
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Spectroscopic and Laser Properties of Different Materials Doped with Pr^{3+} Ions

80%
Mierczyk Z., Kaczmarek S., Kopczyński K., Frukacz Z., Pracka I., Łukasiewicz T.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
407-410
EN
Examined praseodymium doped crystals with 1 at.% of Pr^{3+} ions for Y_{3}Al_{5}O_{12} (YAG), SrLaGa_{3}O_{7} (SLGO) hosts and 3 at.% of Pr^{3+} ions for YAlO_{3} (YAP) hosts were produced using Czochralski method. The luminescence for the range of 200÷800 nm and absorption spectra for a wide range of 200÷6000 nm, for Pr^{3+}:YAG, Pr^{3+}:SLGO and Pr^{3+}:YAP crystals have been measured. A free-running laser emission of λ=0.744 μm for Pr:YAG and λ=0.729 μm for Pr:SLGO for two different transmissions of output mirrors has been obtained.
13
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UV and Gamma Irradiation Effect in Spectroscopic and Lasing Properties of Er^{3+} doped Yttrium-Aluminium Garnet, Yttrium Orthoaluminate and Lithium Niobate Crystals

80%
Kaczmarek S., Pracka I., Mierczyk Z., Kopczyński K., Piramidowicz R., Malinowski M., Kisielewski J., Matkovskii A., Sugak D.
Acta Physica Polonica A
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1996
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vol. 90
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issue 2
411-418
EN
Optical features (absorption and luminescence spectra) for Er^{3+} doped yttrium-aluminium garnet (YAG), yttrium orthoaluminate (YAP) and LiNbO3 crystals as well as their changes after UV and gamma irradiations are presented. Possibility of gamma-induced sensibilization process in Er^{3+} doped crystals is discussed. Positive result for non-pre-annealed gamma-irradiated rods of Er^{3+}:YAG crystal was stated.
14
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Lifetime Measurements of the ^{4}S_{3/2} Level in Erbium Pentaphosphate Monocrystal

80%
Kaczmarek F., Malak H.
Acta Physica Polonica A
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1996
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vol. 89
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issue 5-6
669-674
EN
Lifetime of the main fluorescence level, ^{4}S_{3/2}, of erbium pentaphosphate monocrystal was measured to be 380±20 ns. Direct excitation to higher energy levels, and also indirect excitation with the use of an infrared beam were applied.
15
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Development of Growth Technologies for the Photonic Single Crystals by the Czochralski Method at Institute for Single Crystals, NAS of Ukraine

80%
Kosmyna M., Nazarenko B., Puzikov V., Shekhovtsov A.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
305-313
EN
The present paper briefly overviews the application of the Czochralski method for growth of a set of oxide crystals for photonics, as well as the design of equipment at the Institute for Single Crystals, NAS of Ukraine. The examples of crystal growth and their characterization are described. The simultaneous Q-switched lasing and self-Raman frequency conversion were demonstrated in Nd-doped PbWO_4 and PbMoO_4 crystals grown by the Czochralski method. The slope lasing efficiency obtained for a PbMoO_4:Nd^{3+} laser is the best result for all the crystals with the scheelite-type structure. A detection unit with high scintillation characteristics based on a large volume (V ≈ 350 cm^3) CdWO_4 crystal was produced. Crystal growth procedures and properties of new double tungstate and vanadate crystals are presented, too.
16
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A Short Review on Fluoride Laser Crystals Grown by Czochralski Method at IPEN

80%
Baldochi S., Ranieri I.
Acta Physica Polonica A
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2013
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vol. 124
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issue 2
286-294
EN
In this article there are presented the developments on the crystal growth by the Czochralski method of fluoride laser materials at the Center for Lasers and Applications from Institute of Nuclear and Energy Research, IPEN, Brazil. A brief report of the Czochralski furnace preparation for fluorides growth regarding to its construction materials, influence of the heating assemblies in the thermal profiles and the benefits of using a suitable atmosphere is provided. Moreover, to demonstrate the importance of this technique to the advances on laser systems over the last years there are described the specific growth conditions established to obtain fluoride crystals with suitable properties for practical application as laser hosts. LiREF_4 (RE = rare earth) scheelite crystals have been studied to compare LiYF_4 (YLF) with its isomorphs, including solid solutions of the type-LiY_{1-x}Ln_{x}F_4 (Ln = Gd or Lu) and LiGd_{1-x}Lu_{x}F_4, relating to their optical quality, spectroscopic and laser properties. Some results regarding the development of new laser hosts of these materials doped with Nd, Er, Pr and co-doped Yb, Nd and Tm are also presented. The growth particularities of transition metals doped fluoride crystals such as BaLiF_3:TM (TM = Ni and Co) and LiSrAlF_6:Cr are also reported.
17
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Hydrothermal Synthesis and Microstructural, Optical Properties Characterization of YVO_4 Phosphor Powder

80%
Zhang S., Liang Y., Gao X., Liu H.
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vol. 125
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issue 1
105-110
EN
The phonon energy of YVO_4 crystal is lower than other usual compounds of salt. So it is suitable as host material for down-conversion materials. Hydrothermal method was adopted to synthesize YVO_4 phosphor powder with the use of yttrium oxide and sodium vanadate as raw material. The change in the relative integral intensity of the (200) and (112) diffraction peaks indicates that macroscopic stress in the lattice obviously changes with the elevated hydrothermal reaction temperature. The YVO_4 phosphor powder synthesized involves a certain agglomeration of small particles. The phonon vibration in the YVO_4 originates mainly from the internal vibrations in the vanadium-oxygen tetrahedron, in addition to the Y-O and O-H vibrations. Due to a low phonon energy of only 2.8188 × 10^{-21} J, YVO_4 helps to improve the down-conversion efficiency of rare-earth ions. A bandgap value of approximately 3.8 eV for the synthesized YVO_4 powders leads to good absorption properties in the ultraviolet region. Upon excitation by the 320 nm ultraviolet photon, the intrinsic emission of YVO_4 powders is annihilated, and a broadband emission of VO_4^{3-} near 450 nm is observed at room temperature. The YVO_4 phosphor powder synthesized at 180C exhibits the maximum photoluminescence intensity because of its excellent crystallization.
18
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Comparative Study between Energy Levels of Cr^{3+} and Co^{2+} Ions Doped in MgF_{2} Crystal

80%
Nistora R., Andreici L., Avram N.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
538-540
EN
The aim of this paper is to present a comparison of the energy level schemes of Cr^{3+} (3d^{3} electrons) and Co^{2+} (3d^{7} electrons), each of ions doped, separately, in MgF_{2} crystal. We report on the detailed and consistent crystal field analysis of Cr^{3+} spectra in MgF_{2} crystal and compare with results, previously obtained, for Co^{2+}, doped in same host matrix. The results are based on application of the exchange charge model of crystal field to the calculation of crystal field parameters and energy levels of both ions doped in MgF_{2}.The calculations have been performed on previously optimized geometry of MgF_{2} crystal. The obtained results are compared with experimental data and discussed.
19
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Multiphonon Absorption and Photon Avalanche Criterion in Erbium Doped Materials

80%
Auzel F.
Acta Physica Polonica A
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1996
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vol. 90
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issue 1
7-19
EN
The photon avalanche effect has been recently observed at room temperature in erbium doped fluoride glasses and crystals, in a particularly clear way, displaying simultaneously all the typical features of this effect: (i) existence of a threshold for transmission at the excitation wavelength, (ii) up-conversion excitation threshold, (iii) long delay for threshold establishment. Analysing the first step of the avalanche effect as an anti-Stokes multiphonon absorption, it can be shown why this effect is so clearly observed at room temperature in our erbium studies. Our results are compared with other cases of avalanche, with cases which have been called "looping effects" and "quasi-avalanche" ones.
20
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Modelling of Blue Wavelength Praseodymium Waveguide Lasers

80%
Malinowski M., Mossakowska-Wyszyńska A., Piramidowicz R., Szczepański P., Tyszka-Zawadzka A., Frukacz Z., Pracka I.
Acta Physica Polonica A
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2000
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vol. 97
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issue 2
295-313
EN
Emission and absorption spectra, lifetimes, and branching ratios in the blue spectral region have been experimentally determined for numerous oxide, fluoride and phosphate materials doped with Pr^{3+} ions. The emission cross-sections have been evaluated using the principle of reciprocity. A theoretical model allowing a prediction of the blue lasing characteristics of the praseodymium activated waveguide structures has been developed and employed to the investigated materials.
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