Tm3+/Ho3+ codoped tellurite fiber laser

Continuous-wave and Q-switched lasing from a Tm 3+ /Ho 3+ codoped tellurite fiber is reported. An Yb 3+ /Er 3+ -doped silica fiber laser operating at 1.6μm was used as an in-band pump source, exciting the Tm 3+ ions into the F 4 3 level. Energy is then nonradiatively transferred to the upper laser level, the I 7 5 state of Ho 3+ . The laser transition is from the I 7 5 level to the I 8 5 level, and the resulting emission is at 2.1μm . For continuous wave operation, the slope efficiency was 62% and the threshold 0.1W ; the maximum output demonstrated was 0.16W . Mechanical Q switching resulted in a pulse of 0.65μJ energy and 160ns duration at a repetition rate of 19.4kHz

Rare-Earth Doped Phosphate Glass Fibers

We report on the fabrication and characterization of phosphate fibers doped with Yb and Yb/Er ions. Optical amplification and laser operation are demonstrated in short-length devices

Phosphate glass fibrous scaffolds: tailoring of the properties and improvement of the bioactivity through the incorporation of mesoporous glasses

Introduction. Synthetic bone scaffolds are proposed as an alternative to the use of bone grafting technique for bone regeneration. Porous scaffold obtained from glass fibres randomly arranged into a mould shows an interconnected porosity generated by the free space between fibres and they do not need of any further material or processing step before sintering. In this work, a resorbable phosphate glass was selected for the fibre drawing and bioactive mesoporous glasses with different morphology and size were incorporated into the fibrous scaffold to combine the resorption property of the fibres with the bioactivity of the mesoporous powders. Materials and methods. Fibres of a TiO2-containing phosphate glass (TiPS2.5) were fabricated following the preform drawing approach as described elsewhere [1]. A dense silica-based bioactive glass (CEL2) [2] was produced by melt quenching as reference sample. Spherical micro-sized mesoporous glass based on SiO2-CaO system (SD_MBG) was produced by an aerosol-assisted spray-drying technique [3]. Cu-containing (85SiO2-13CaO-2CuO, % mol, referred as Cu_BGn2%) mesoporous glass nanoparticles were synthetized by an ultra-sound assisted sol-gel method to impart antibacterial properties. To fabricate the fibrous scaffolds, the selected powder and phosphate glass fibres, cut at precise length, were placed in a beaker containing 2 ml of ethanol. After ethanol evaporation, the powder/fibre mixture was randomly placed inside a zirconia cylindrical mould [4]. After the thermal treatment, the scaffolds were analyzed through micro-CT in order to investigate their inner structure. Furthermore, their ability to form hydroxyapatite was studied by soaking them in a simulated body fluid (SBF). The scaffold morphology before and after immersion in SBF was studied by FESEM. Results and discussion. FESEM micrographs show that CEL2 are not well incorporated into the fibre surface. On the contrary, SD-MBG (Figure 1.a, Figure 1.b and Figure 1.d) and Cu_BGn2% particles homogeneously cover the whole surface. Micro-CT analysis did not reveal the presence of powder agglomerates for all the observed scaffolds and showed a homogeneous porosity of 58 vol.% for CEL2/fibre scaffold, 53 vol.% for SD_MBG/scaffold (Figure 1.c) and 33% for Cu_BGn2%/scaffold. In CEL2/fibre scaffolds, glass particles were removed during soaking in SBF, leaving some pits on the fibre surface: FESEM analysis revealed few particles still anchored to the scaffold surface after 7 days. On the contrary, after 7 days in SBF, SD-MBG and Cu_BGn2% particles were clearly visible on the surface of the scaffolds and after 1 day of soaking in SBF, they appeared (Figure 2) fully covered with a HA layer, showing the typical "cauliflower-like" morphology. Conclusion. The incorporation of mesoporous bioactive glass powder in the phosphate glass fibrous scaffold resulted to be a very interesting strategy to impart multifunctional properties to the scaffold. These promising results encourage further investigation in order to fully exploit the ability of mesoporous particles to act as a system for smart release of therapeutic ions and drugs

Single-frequency, pulsed Yb3+-doped multicomponent phosphate power fiber amplifier

High-power, single-frequency, pulsed fiber amplifiers are required in light detection and ranging, coherent laser detection, and remote sensing applications to reach long range within a short acquisition time. However, the power-scaling of these amplifiers is limited by nonlinearities generated in the optical fibers, in particular by stimulated Brillouin scattering (SBS). In this regard, the use of multicomponent phosphate glasses maximizes the energy extraction and minimizes nonlinearities. Here, we present the development of a single-stage, hybrid, pulsed fiber amplifier using a custom-made multicomponent Yb-doped phosphate fiber. The performance of the phosphate fiber was compared to a commercial Yb-doped silica fiber. While the latter showed SBS limitation at nearly 6.5 kW for 40 cm length, the maximum achieved output peak power for the multicomponent Yb-doped phosphate fiber was 11.7 kW for 9 ns pulses using only 20 cm with no sign of SBS

New Developments in Tellurite Glass Fibers

Recent developments on the manufacture of tellurite glass fibers are presented. Technical issues related to glass synthesis, preform manufacturing and fiber drawing as well as prospective of commercial exploitation are discussed

Novel microstructured fibres for supercontinuum generation

We report recent progress on the fabrication of photonic crystal fibre from ZBLAN and tellurite glasses and their application to generating broadband supercontinua

Analysis of Faraday effect in multimode tellurite glass optical fiber for magneto-optical sensing and monitoring applications

The design and fabrication of a tellurite glass multimode optical fiber for magneto-optical applications are presented and discussed. The analysis of the polarization shows that an optical beam, linearly polarized at the fiber input, changes to elliptically polarized with an ellipticity of 1∶4.5 after propagating down the fiber. However, the elliptical distribution remains unchanged with or without an applied magnetic field, demonstrating that no circular dichroism occurs within the fiber. The Verdet constant of the tellurite glass in the fiber is measured to be 28 0.5 rad · T ·m−1, diverging by less than 3% from the Verdet constant found on the same glass composition in bulk form. These results demonstrate the feasibility to develop reliable tellurite glass fibers by the preform drawing method for magneto-optical applications

Spectroscopy of thulium and holmium heavily doped tellurite glasses

In this study, we report spectroscopic properties of Tm3þ and Ho3þ codoped tellurite glasses over a wide dopant concentration range in order to assess their potential laser performance under 790 nm diode laser excitation. The impact of Tm3þ and Ho3þ concentrations is investigated to identify specific candidates for fiber laser operation. The emission cross section is calculated and discussed, as well as the gain coefficient of this type of glasses. Energy transfer microparameters and critical ion distances are determined for 3H4, 3F4 (Tm3þ), and 5I7 (Ho3þ) emission levels in the framework of diffusionlimited regime and dipole-dipole interaction. We also report thermal properties of tested glasse

Novel Tm3+-doped fluorotellurite glasses with enhanced quantum efficiency

In this paper, new highly Tm3+-doped tellurite glasses with host composition 75TeO2-xZnF2-yGeO2-12PbO-3Nb2O5 [x(5-15), y(0-5) mol%] are presented and compared to the Tm-doped tellurite glasses based on the traditional host composition: 75TeO2-20ZnO-5Na2O mol%. Enhanced quantum efficiency from 3F4 level was observed for the proposed glasses and thermal stability and viscosity values make them suitable for optical fiber drawing. Besides the host composition, substantial influence of Tm3+ concentration on luminescence and lifetime of excited 3F4 and 3H4 states were discusse

Efficient ∼2 μm Tm-doped tellurite fiber laser

Laser emission in the range of 1.88-1.99 μm from a Tm-doped tellurite fiber is demonstrated when pumped with a diode-pumped Er /Yb-doped silica fiber laser operating at 1.57-1.61 μm. This pump source excites the Tm ions directly into the F upper laser level and yields an output power of 280 mW with a slope efficiency of 76% in a 99%-12% laser cavity arrangement and a 32 cm long fiber. This result is very close to the Stokes efficiency limit of ∼80%. This is, to the authors' knowledge, the first demonstration of high efficiency lasing in a tellurite fiber at wavelengths longer than 1.56 μm