A. A. Man’shina

Up-conversion luminescence efficiency in Er-doped chalcogenide glasses

Abstract The efficiency of up-conversion luminescence of Er 3+ ions (excited by laser light operating at 810 nm) in the GeS 2 –Ga 2 S 3 :Er 2 S 3 system strongly depends on the energy position of the fundamental absorption edge. This dependence is due to non-radiative energy exchange between the electronic subsystem of the glassy matrix and excited levels of Er 3+ ions. In chalcogenide glasses Ge and Ga atoms are fourfold coordinated. Except for the M (M=Ge, Ga)–S heterobonds, the rest are M–M homobonds. These homobonds can be detected with Raman spectroscopy. The energy position of the absorption tail of the fundamental band depends on the concentration of M–M homobonds. When the concentration of these bonds increases the absorption edge shifts to longer wavelengths and the intensity of up-conversion luminescence decreases. The relative concentration of M–M bonds depends not only on composition of the glassy matrix but also on the synthesis and on concentration of extrinsic impurities such as OH − , SH − and –CH 2 –. Another cause of reduction of up-conversion luminescence intensity is the inhomogeneous distribution of REI in the Ga 2 S 3 –GeS 2 glasses. The simple model describing dependence of luminescence intensity on type of REI distribution in the glassy matrix is discussed.

Sol-gel synthesis and luminescent properties of YVO4 : Eu nanoparticles

Experimental results on the synthesis of luminescent YVO4: Eu nanoparticles with the method of metalopolymer gel decomposition are presented. The sizes of the coherent scattering regions according to the X-ray diffraction data range from 25 to 40 nm and increase with the increase of the annealing temperature from 800 to 1000°C. It was shown that the obtained nanoparticles demonstrate good luminescent properties. The luminescence intensity and lifetime of the excited state increase with the increase of the annealing temperature. Nanoparticles are good candidates to use as luminescent labels.

Laser-Induced Copper Deposition on the Surface of an Oxide Glass from an Electrolyte Solution

Continuous copper patterns were grown on the surface of oxide glass substrates through laserinduced chemical liquid-phase deposition (LCLD). The deposition was performed with the use of a continuouswave argon laser operating in a multimode regime. The deposition occurred as a result of the reducing chemical reaction initiated by laser radiation. Continuous metal patterns were produced by scanning focused laser radiation along the substrate-electrolyte interface. The morphology and the chemical composition of the deposited patterns were examined with the use of a CEM-SCAN 4 DV scanning electron microscope equipped with an energy-dispersive spectrometer. The morphology of the deposited patterns was investigated as a function of the laser radiation power and the number of scans. It was demonstrated that high-quality continuous patterns can be fabricated using one scan of the laser beam.

Non-radiative energy transfer from Er3+ ions to the electronic states of the chalcogenide glass matrix

Lifetime spectroscopy of the chalcogenide systems Ga-Ge-S:Er 3+ and Ga-Ge-S-Se:Er 3+ has shown that the non-radiative energy transfer from rare-earth ions to the electronic states of the chalcogenide matrix is important. Numerical calculations of transition probabilities (W R , W mph , W CR ) allowed estimation of the probability of the energy transfer to the chalcogenide matrix. It was found that when the optical bandgap of the matrix approaches the Er 3+ level, the probability of such energy transfer process will increase as long as a complete resonance is not achieved.

Laser-induced synthesis of metal–carbon materials for implementing surface-enhanced Raman scattering

Metal–carbon materials exhibiting surface-enhanced Raman scattering have been synthesized by laser irradiation of colloidal systems consisting of carbon and noble metal nanoparticles. The dependence of the Raman scattering intensity on the material composition and laser irradiation conditions has been investigated. The possibility of recording the Raman spectrum of organic dye rhodamine 6G, deposited in amount of 10–6 M on the substrate obtained from a colloidal solution is demonstrated.

Analysis of the spectroscopic parameters of chalcogenide glasses in the Ga-Ge-S: Er3+ system

The spectroscopic characteristics of chalcogenide glasses in the Ga-Ge-S: Er3+ system are determined. The oscillator strengths, the Judd-Ofelt intensity parameters, the probabilities of spontaneous radiative transitions, and the radiative lifetimes of levels are calculated from the absorption spectroscopy data for two series of Ga-Ge-S chalcogenide glasses doped with Er3+ ions. In the first series, the Er2S3 content is varied from 0.49 to 4.64 mol % at the fixed composition of the glass matrix (0.15Ga2S3 · 0.85GeS2). In the second series, the Ga2S3 content is varied from 10 to 30 mol % at the fixed Er2S3 content (1.94 mol %). The aforementioned spectroscopic parameters are analyzed as a function of the chalcogenide glass composition. It is revealed that the values of the oscillator strengths and the probabilities of spontaneous radiative transitions in Er3+ ions in the chalcogenide matrix are larger than those in phosphate, germanate, and tellurite matrices.

The formation of optical phase structures in the volume of phosphate glasses by means of thermal diffusion caused by the action of femtosecond laser radiation

This paper discusses the physicochemical properties (density, microhardness, thermal effects, electrical conductivity, calculated volumes of fluctuation microvoids, and spectral studies) of phosphate and niobium–phosphate glasses containing lithium, sodium, and potassium oxides. It shows that, when one alkali oxide is replaced by another equivalent one, there is a nonlinear variation of the electric parameters, while all the other parameters vary linearly. Scanning with a femtosecond laser in the volume of lithium (sodium) niobium–phosphate glass produces high-contrast optical elements by means of the diffusion of lithium (sodium) ions from the focal center to the edges and counterdisplacement of niobium from the edges to the center.

Optic properties of niobium-phosphate glasses containing lithium, sodium, and potassium oxides

The dependence of the optic properties of niobium-phosphate glasses containing alkali metal oxides on their composition and structural features is investigated. Along with the increase of the niobium oxide content, a shift of the optic absorption boundary to the long-wavelength range and a substantial increase of the refraction index (from 1.50 to 1.73) are observed. The increase of the alkali metal mass results in the decrease of the refraction index and a shift to the short-wavelength range. The correlation between the length of polyphosphate groups and the type of alkali oxide is registered: the chain length increases from lithium to potassium.