Jacek Zmojda

Influence of BaF2 and activator concentration on broadband near-infrared luminescence of Pr3+ ions in gallo-germanate glasses.

Thermal stability and broadband NIR luminescence of Pr(3+) doped gallo-germanate glasses with BaF2 have been studied. The thermal factors are larger for glass samples with low BaF2 content exhibiting good thermal stability against devitrification. Luminescence due to (1)D2 → (1)G4 transition of Pr(3+) was measured under 450 nm excitation. The (1)D2 measured lifetimes depend critically on activator concentration, but remain nearly unchanged with BaF2 content. The emission linewidth, the emission cross-section, the figure of merit (FOM) and the σem x FWHM product are relatively large, suggesting that Pr(3+)-doped gallo-germanate glasses with presence of BaF2 are promising as gain media for broadband near-infrared amplifiers.

Broadband near infrared emission in antimony-germanate glass co-doped with erbium and thulium ions

Abstract. Antimony-germanate glasses co-doped with Er3+/Tm3+ ions as a material for active waveguides application have been investigated. In result of optimizations of rare earths, concentration wide (ΔλFWHM=420  nm) luminescence emission in the range of 1.4 to 1.9 μm was obtained for molar composition of 1%Er2O3: 0.25%Tm2O3. The influence of the molar ratio of active ions on the luminescence spectra has been investigated. Luminescent properties of fabricated glass indicate that elaborated glass is promising material for broad tunable integrated laser sources and broadband optical amplifiers.

Structural and optical study on antimony-silicate glasses doped with thulium ions.

Structural, spectroscopic and thermal properties of SiO₂-Al₂O₃-Sb₂O₃-Na₂O glass system doped with 0.2 mol% Tm₂O₃ have been presented. Synthesis of antimony-silicate glasses with relatively low phonon energy (600 cm(-1), which implicates a small non-radiative decay rate) was performed by conventional high-temperature melt-quenching methods. The effect of SiO₂/Sb₂O₃ ratio in fabricated Tm(3+) doped glass on thermal, structural and luminescence properties was investigated. On the basis of structural investigations decomposition of absorption bands in the infrared FTIR region was performed, thus determining that antimony ions are the only glass-forming ions, setting up the lattice of fabricated glasses. Luminescence band at the wavelength of 1.8 μm corresponding to (3)F₄→(3)H₆ transition in thulium ions was obtained under 795 nm laser pumping. It was observed that combination of relatively low phonon energy and greater separation of optically active centers in the fabricated glasses influenced in decreasing the luminescence intensity at 1800 nm.

Analysis of thermal and structural properties of germanate glasses co-doped with Yb3+/Tb3+ ions ☆

In the work the new glass compositions in the GeO2-GaO-BaO system have been prepared and thermal, structural properties of in germanate glasses co-doped with Yb(3+)/Tb(3+)ions were studied. Glasses were obtained by conventional high-temperature melt-quenching technique. The study of the crystallization kinetics processes of glasses co-doped with 0.7Yb2O3:0.7Tb2O3 was performed with DSC measurements. The activation energies have been calculated using Freedman analysis and verified with the Flynn-Wall-Ozawa method. In this order, the DSC curves have been registered with different heating rates, between 5 and 15 degrees/min. The structure of fabricated glasses has been studied by infrared and Raman spectroscopes. The effect of heat treatment on the structural properties was determined. In all glass samples the dominated infrared absorbance band at 800cm(-1) corresponds to asymmetric stretching motions of GeO4 tetrahedra containing bridging (Ge-O(Ge)) and non-bridging (Ge-O(-)) oxygens. Additionally, the influence of heat treatment on the luminescent properties was evaluated. Strong luminescence at 489, 543, 586 and 621nm corresponding to (5)D4→(7)FJ (J=6, 5, 4, 3) transitions was measured. The highest upconversion emission intensity was obtained in the germanate glass co-doped with 0.7Yb2O3/0.7Tb2O3.

Properties of Eu3+ doped poly(methyl methacrylate) optical fiber

Abstract. The proposition of trivalent europium as a luminescent dopant in poly(methyl methacrylate) (PMMA) host is presented. Optical characterization and fabrication technology of the Eu3+ doped polymeric fiber is shown. The proposed luminescent material exhibits an intense luminescence under 355- and 405-nm excitation. Additionally, the measured decay time (0.51 ms, D50→F72 transition) at third harmonic Nd:YAG excitation showed low luminescence quenching in Eu3+ chelate doped PMMA. The luminescent properties and influence of spectral attenuations on the luminescence shape in fabricated fibers are also presented.

Helical core optical fibre made of Nd3+/Yb3+-doped oxyfluoride silicate glass

The properties of helical-core optical fibre made by authors from Nd3+/Yb3+-doped oxyfluoride silicate glass are presented. The construction and forming conditions of the helical-core optical fibre enabled to obtain the helix pitch from several mm and the off-set ranging from 10 μm to 200 μm. The paper also presents optimisation of Nd3+/Yb3+ ratio to enhance the emission bandwidth at 1 μm. In consequence of matching the values of the emission cross-section σem(Nd)and the absorption cross-section σabs(Yb) in the glass doped with 0.15Nd3+:0.45Yb3+ a broad (Δλ = 100nm) luminescence band in the vicinity of 1μm was obtained, which was the result of overlapping emission transitions: 2F5/2→2F7/2 in ytterbium and 4F3/2→4I11/2 in neodymium.

NIR to visible upconversion in double – clad optical fiber co-doped with Yb 3+ /Ho 3+

Spectroscopic properties of a fabricated double – clad, off-set core antimony - germanate optical glass fiber co-doped with Yb3+/Ho3+ has been investigated. Upconversion luminescence of holmium ions at the wavelengths of 549 nm (5S2 (5F4) → 5I8) and 658 nm (5F5 → 5I8) was obtained as a result of the energy transfer between Yb3+ and Ho3+ ions. Glass characterized by highest intensity of upconversion luminescence (1Yb2O3/0.5Ho2O3 mol%) was used as core of double-clad optical fiber. Upconversion amplified spontaneous emission in the fabricated double – clad, off-set core optical fiber was obtained. The intensity emission ratio red (5F5→5I8)/green (5S2 (5F4)→5I8) of the fabricated optical fiber is several times higher than in bulk glass. Reabsorption of the ASE signal along the fiber resulting from Ho3+: 5S2(5F4) → 5I8,5F5 → 5I8 transitions transition was observed.

Rare-earth doped materials for optical waveguides

In the paper the analysis of luminescence emission in the VIS spectra range of fabricated multicomponent glasses doped with rare-earth ions and PMMA doped with dyes were presented. Up-conversion emission in: germanate glass co-doped with 0.5Yb₂O₃/0.75Eu₂O₃ mol% under 976 nm excitation has been investigated. Down-conversion mechanism was analyzed in phosphate glasses doped with 0.5 mol% Tb₂O₃ and PMMA co-doped with fluorescein and rhodamine B. Phosphosilicate glasses doped with Er³⁺ ions have been also studied in order to fabricate target for manufacturing planar waveguides by RF-sputtering deposition. Fabricated materials can be used for fabrication of optical fibers. In result blue up-conversion emission in double-clad optical fiber with Yb³⁺/Tm³⁺- doped core was presented.

The xanthene dyes doped PMMA microspheres for optical sensor applications

The numerous applications of luminescent glass and polymeric microspheres are well known. The polymeric structures are popular as they assure good processability (solid and porous structures) and high doping level. The article presents the suspension polymerization process of polymeric (PMMA) microspheres doped by xanthene dyes: Fluorescein (Fl) and Rhodamine B (RhB). The bright luminescence at wavelengths 510nm 595nm respectively was recorded. The shape and dimension distributions of fabricated microspheres were optically determined. The article presents also potential applications of fabricated luminescent microspheres.

Structural and optical properties of antimony-germanate-borate glass and glass fiber co-doped Eu3+ and Ag nanoparticles

In the paper analysis of structural and luminescent properties of antimony-germanate-borate glasses and glass fiber co-doped with 0.6AgNO3/0.2Eu2O3are presented. Heat treatment of the fabricated glass and optical fiber (400 °C, 12 h) enabled to obtain Ag nanoparticles (NPs) with average size 30-50 nm on their surface. It has been proofed that silver ions migrate to the glass surface, where they are reduced to Ag0 nanoparticles. Simultaneously, FTIR analysis showed that heat treatment of the glass and optical fiber increases the local symmetry of the Eu3+ site.