130 research outputs found
Optical spectroscopy of Er3+-doped LaVO4 crystal
No full textTransparent single crystals of erbium-doped LaVO4 in form of platelets having an average size 0.5 x 2 x 2 mm(3) were obtained by the flux method using Pb2V2O7 as the solvent. inductively coupled plasma (ICP) measurement revealed that the actual Er/La = 0.3% molar ratio in the crystals is lower than Er/La = 1% nominal molar ratio due to significant difference of ionic radii of La and Er. Luminescence spectra and luminescence decay curves for Er3+ transitions in the visible and near infrared region were recorded. Unpolarized Raman spectrum of undoped LaVO4 crystal was acquired, too. Up-converted green emission following excitation at 808 and 970 nm was observed and dependence of its intensity on incident excitation power was determined. Based on experimental data gathered the relaxation dynamics of excited states of Er3+ was analyzed and mechanisms involved in the up-conversion phenomena were discussed. (C) 2009 Elsevier B.V. All rights reserved
Luminescence spectroscopy of Er3+-doped and Er3+, Yb3+-codoped LaPO4 single crystals
No full textLaPO4 single crystals lightly doped with Er3+, and codoped with Er3+ and Yb3+ have been grown by spontaneous nucleation in a lead phosphate flux. Absorption and luminescence spectra have been measured in the visible and near-IR regions and the excited state dynamics has been studied upon pulsed laser excitation. The obtained results have allowed the evaluation of the effective emission cross-sections around 1.5 mu m, that have been found to be similar to important oxide laser crystals doped with Er3+. Efficient visible upconversion has been observed upon excitation at 980 nm in the codoped crystals. This behaviour is attributed to Yb3+-Er3+ energy transfer processes
Optical Methods in Characterization of HTSC Thin Film Substrates
No full textShort 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 and SrLaAlO crystals are presented and discussed
Disordered Nd-Doped Crystals for Diode Pumping
No full textSome 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 ABCO and ABCO 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
Influence of Temperature on Refractive Indices of BaLaGaO and SrLaGaO
No full textA simple theoretical approach based on Kramers-Krönig relations predicts well the dispersion and birefringence of BaLaGaO and SrLaGaO. 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 BaLaGaO and SrLaGaO is stable with respect to the temperature region of 300-550 K. The refractive indices increase linearly at a rate of 2 × 10 K with increasing temperature
Material Parameters Characterizing the Performance of Flashlamp Pumped BaLaNdGaO Laser
No full textPhysical properties of optically uniaxial BaLaNdGaO 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 BaLaNdGaO have been defined
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