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1

Disordered Nd-Doped Crystals for Diode Pumping

100%

Ryba-Romanowski W.

Acta Physica Polonica A

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1993

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vol. 84

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issue 5

945-952

EN

Some interest has been directed recently to neodymium doped crystals with strong inhomogeneous broadening of absorption bands which are believed to be better suited for diode pumping than the crystals with ordered lattice. The disordered Nd-doped crystals may be obtained in two ways. The first one is to introduce a structural disorder in ordered lattice by substituting partially one or more cations by cations with different charges. Alternatively, the compounds with inherently disordered structure are synthesized and doped with Nd. We consider two wide families of compounds of general formulae ABC_{3}O_{7} and ABCO_{4} where A stands for Ca, Sr, Ba, B is Y or rare earth and C stands for Ga or Al. Both the families form the crystals with inherently disordered structure and can accept an appreciable amount of Nd. Results of structural and spectroscopic investigations are used to determine material's parameters relevant to laser performance. Comparison of several disordered crystals is made and their suitability for diode pumping is discussed.

2

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.

3

Influence of Temperature on Refractive Indices of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}

51%

Ryba-Romanowski W., Gołąb S., Berkowski M.

Acta Physica Polonica A

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1993

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vol. 83

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issue 2

167-172

EN

A simple theoretical approach based on Kramers-Krönig relations predicts well the dispersion and birefringence of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}. In the whole transparency region the birefringence of both compounds is too low to offset dispersion in the process of a second harmonic generation, thus the crystals cannot be made phase matchable. Birefringence of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7} is stable with respect to the temperature region of 300-550 K. The refractive indices increase linearly at a rate of 2 × 10^{-5} K^{-1} with increasing temperature.

4

Material Parameters Characterizing the Performance of Flashlamp Pumped BaLa_{1-x}Nd_{x}Ga_{3}O_{7} Laser

51%

Ryba-Romanowski W., Gołąb S., Berkowski M.

Acta Physica Polonica A

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1991

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vol. 79

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issue 4

501-506

EN

Physical properties of optically uniaxial BaLa_{1-x}Nd_{x}Ga_{3}O_{7} crystals have been investigated. Specific heat, thermal expansion coefficients, thermal diffusivity, Young modules and Poisson ratios of the crystal have been determined. Basing upon these parameters and the available spectral data the operating conditions for lasers employing rods made of BaLa_{1-x}Nd_{x}Ga_{3}O_{7} have been defined.

5

Relaxation of the ^{4}S_{3/2} Level of Er^{3+} in Cs_{2}NaErCl_{6}

51%

Dominiak-Dzik G., Gołąb S., Ryba-Romanowski W.

Acta Physica Polonica A

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1993

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vol. 84

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issue 5

941-944

EN

Octahedral (O_{h}) symmetry of the RE^{3+} sites in the Cs_{2}NaRECl_{6} crystals removes all of the electric dipole intensity from the 4f-4f transitions. Thus the decay of luminescence originating in the excited states of RE ions is governed by phonon assisted (vibronic) transitions, multiphonon relaxation and phonon assisted energy transfer (cross relaxation and energy migration to impurities). Contribution of these processes to the decay of the ^{4}S_{3/2} state of erbium in Cs_{2}NaErCl_{6} has been studied in the 4.2-300 K temperature region. It has been concluded that at low temperatures the ^{4}S_{3/2} state decays exclusively by vibronic transitions. At about 100 K the cross relaxation via the ^{4}I_{9/2} state becomes operative. Efficiency of this process grows strongly with increasing temperature, reducing the ^{4}S_{3/2} lifetime by almost three orders of magnitude. No evidence has been found that multiphonon relaxations contribute to the decay of the ^{4}S_{3/2} state.

6

Luminescence and Lifetimes of Pr^{3+} Excited States in KLa_{1-x}Pr_{x}(MoO_{4})_{2} and KLa_{1-x}Pr_{x}(WO_{4})_{2} Crystals

45%

Macalik L., Ryba-Romanowski W., Gołąb S., Hanuza J., Legendziewicz J.

Acta Physica Polonica A

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1996

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vol. 90

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issue 2

301-306

EN

Single crystals of double molybdates and tungstates of the formula KLa_{1-x}Pr_{x}(MO_{4})_{2} (M = Mo, W) with a concentration of Pr^{3+} ions ranging from x=0.1 to x=0.005 have been prepared. Their electronic absorption and emission spectra have been measured and discussed as well as related to their crystal structures. Both the multiphonon relaxation and cross relaxation contribute to the decay of the ^{3}P_{0} level of Pr^{3+} in these two matrices.

7

Optical Study of SrLaGaO_{4} and SrLaGa_{3}O_{7} Doped with Nd^{3+} and Yb^{3+}

45%

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.

8

Czochralski Growth and Optical Properties οf (Lu_{x}Gd_{1-x})_2SiO_5 Solid Solution Crystals Single Doped with Sm^{3+} and~Dy^{3+}

39%

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

Optical Spectroscopy of the Nd^{3+} Luminescence Centres in the Sr_{4}B_{14}O_{25}:Nd Crystal

39%

Padlyak B., Ryba-Romanowski W., Lisiecki R., Oseledchik Y., Prosvirnin A., Kudryavtcev D., Svitanko N.

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issue 1

104-110

EN

Optical absorption, emission and luminescence kinetics of Nd^{3+} centres in the new borate crystal with Sr_{4}B_{14}O_{25}:Nd (Nd content 0.2 wt.%) composition are investigated and analysed. The oscillator strengths (P_{theor} and P_{exp}) for observed absorption transitions and phenomenological intensity parameters Ω_t (Ω_2=1.59×10^{-20} cm^{-1}, Ω_{4} = 2.06 × 10^{-20} cm^{-1}, and Ω_{6} = 2.28 × 10^{-20} cm^{-1} were calculated based on the standard Judd-Ofelt theory. Using Ω_t parameters the radiative transitions rates (W_{r}), branching ratios (β) and radiative lifetime (τ_{rad}) for Nd^{3+} centres in the Sr_{4}B_{14}O_{25}:Nd crystal were calculated and analysed. Measured lifetime (τ_{exp} = 105 and 93 μs at T = 10 and 300 K, respectively) is compared with this calculated (τ_{rad} = 331 μs) and quantum efficiency for Nd^{3+} centres from ^{4}F_{3/2} emitting level in the Sr_{4}B_{14}O_{25}:Nd crystal is estimated (η ≅ 30%). Incorporation peculiarities and local structure of Nd^{3+} luminescence centres in the Sr_{4}B_{14}O_{25} crystal and corresponding glass with 4SrO-7B_{2}O_{3} composition are discussed on the basis of referenced X-ray diffraction data and presented results.

10

Investigation of As Grown and Induced Structural Defects in SrLaXO_{4} (x = Al, Ga) Crystals

39%

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.

11

Magnetic Resonance and Dielectric Studies of a Nonlinear La_3Ga_{5.5}Ta_{0.5}O_{14} Single Crystal Doped with Erbium

33%

Bodziony T., Typek J., Orlowski M., Majszczyk J., Wabia M., Berkowski M., Ryba-Romanowski W., Guskos N., Likodimos V., Anagnostakis E.

Acta Physica Polonica A

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2003

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vol. 103

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issue 2-3

315-322

EN

Single crystal of erbium doped La_3Ga_{5.5}Ta_{0.5}O_{14} grown by the Czochralski method have been investigated by electron paramagnetic resonance and dielectric spectroscopy methods. Dielectric permittivity ε measurements performed in 90-440 K temperature range have shown negligible dispersion for 1 kHz - 1 MHz frequencies and a Curie-Weiss type behaviour with C=47700 K andθ=-340 K. Electron paramagnetic resonance studies have revealed the presence of two different paramagnetic, monoclinic centres. The calculated g factor values are: g_1=1.449, g_2=11. 534, g_3=4.24 for the main M_1 centre and g_1=1.98, g_2=4.169, g_3=4.25 for the weaker M_2 centre. The temperature dependence of EPR line intensity for centre M_1 and M_2 is quite different - while lines attributed to M_1 could only be observed at low temperatures, below 20 K, lines of M_2 centre persisted up to 200 K. The M_1 centre is connected with Er^{3+} ion entering substitutionally into La^{3+} site, while M_2 is probably connected with 3d ions at the same site, unintentionally introduced into the material as an admixture.

Refine search results

Disordered Nd-Doped Crystals for Diode Pumping

Optical Methods in Characterization of HTSC Thin Film Substrates

Influence of Temperature on Refractive Indices of BaLaGa_{3}O_{7} and SrLaGa_{3}O_{7}

Material Parameters Characterizing the Performance of Flashlamp Pumped BaLa_{1-x}Nd_{x}Ga_{3}O_{7} Laser

Relaxation of the ^{4}S_{3/2} Level of Er^{3+} in Cs_{2}NaErCl_{6}

Luminescence and Lifetimes of Pr^{3+} Excited States in KLa_{1-x}Pr_{x}(MoO_{4})_{2} and KLa_{1-x}Pr_{x}(WO_{4})_{2} Crystals

Optical Study of SrLaGaO_{4} and SrLaGa_{3}O_{7} Doped with Nd^{3+} and Yb^{3+}

Czochralski Growth and Optical Properties οf (Lu_{x}Gd_{1-x})_2SiO_5 Solid Solution Crystals Single Doped with Sm^{3+} and~Dy^{3+}

Optical Spectroscopy of the Nd^{3+} Luminescence Centres in the Sr_{4}B_{14}O_{25}:Nd Crystal

Investigation of As Grown and Induced Structural Defects in SrLaXO_{4} (x = Al, Ga) Crystals

Magnetic Resonance and Dielectric Studies of a Nonlinear La_3Ga_{5.5}Ta_{0.5}O_{14} Single Crystal Doped with Erbium