Search

Emissions at 2.7 μm from telluride glasses with various Er 2 O 3 doping concentrations are investigated. The prepared glasses have excellent thermostability and high rare-earth solubility. Judd–Ofelt parameters are calculated based on the absorption spectra. A large emission cross section (1.12 × 10 −20 cm 2 ) and a high spontaneous radiative coefficient (57.8 s −1 ) are obtained at 2.7 μm. The fluorescence properties of glasses with different concentrations are analyzed and presented. An Er 3+ -doped fiber is fabricated via a rod-in-tube technique, and the loss at 1310 nm is ∼2.1 dB/m measured by using the cut-back method. Strong upconversion emission caused by intense pump absorption is observed from the Er 3+ doped fiber under excitation by a 980 nm laser diode (LD). Telluride glasses with high Er 3+ doping concentration and good thermal property are prepared. Energy transfer processes for 1.5 μm, and 2.7 μm, as well as visible emission are fully discussed. Enhanced 2.7 μm emission is achieved from the bulk glass. An Er 3+ doped fiber is successfully drawn, and strong upconversion emission is observed in the fiber. [ABSTRACT FROM AUTHOR]

Abstract: Tm2O3-doped multi-component silicate glasses without alkali ions are prepared using a conventional melt quenching method. The Judd–Ofelt theory is applied to calculate the intensity parameters of the resultant glass. The intensity parameters of silicate glasses without alkali ions are larger than those of silicate glasses with alkali ions. The spontaneous radiation probability of the transition from 3F4 to 3H6 of glasses without alkali ions is 191.89s−1, which is larger than that of glasses with alkali ions. Moreover, the measured lifetime of the 3F4 energy level of glasses is larger too. Emission cross section results show a maximum value 3.89×10−21 cm2 at 1882nm. These findings indicate that the glass in this study can be used to realize ~2μm lasers. The effect of variations in Tm2O2 concentration on the emission properties is also studied. Cross-relaxation and emission intensity enhance with increasing Tm2O3 content. However, the lifetime of the 3F4 level decreases because of concentration quenching. The influence of OH groups on the emission properties is also investigated. [Copyright &y& Elsevier]

The spectroscopic properties of 2-μm emission in Ho 3+ -doped lanthanum–tungsten–tellurite glasses with different Ho 2 O 3 concentrations were investigated. The strongest emission was observed in a glass sample doped with 0.5 mol% Ho 2 O 3 , with a fluorescence lifetime of 3.16 ms and a emission cross section of 6.97×10 −21 cm 2 at 2040 nm. For this composition, no obvious changes in the emission properties and fluorescence lifetime were observed at temperatures of 295–350 K. Using this 60TeO 2 –30WO 3 –9.5La 2 O 3 –0.5Ho 2 O 3 glass as a core material, Ho 3+ -doped double cladding fiber with a core diameter of 14 μm and a numerical aperture of 0.12 was developed. A maximum laser output power of 34 mW at 2040 nm was achieved with a 9-cm-long Ho 3+ -doped tellurite glass fiber. To the best of our knowledge, this study presents the first report on the 2-μm laser output from a Ho 3+ -doped tellurite oxide glass fiber resonantly pumped by a 1.94 μm Tm-fiber laser. [ABSTRACT FROM AUTHOR]

Ho 2 O 3 -doped transparent tellurite glass–ceramics containing a metastable cubic crystalline phase were prepared. The structure, mechanical properties, 2-μm fluorescence, and decay times of the glass and glass–ceramics were investigated. The Judd–Ofelt intensity parameters, spontaneous radiative probability, and absorption and stimulated-emission cross-sections were calculated. After crystallization, the tellurium coordination number increased (3/3 + 1 → 4), which indicates that the structure changed substantially. The density, refractive index, and Knoop hardness of the glass–ceramics were enhanced compared with those of the precursor glass. After heat treatment, the spontaneous radiative probability and maximum stimulated emission cross-section increased to 172.24 s −1 and 0.744 × 10 −20 cm 2 , respectively. Moreover, the 2-μm emission intensity of the glass–ceramic increased threefold under excitation by a 640-nm laser diode. The lifetime of the Ho 3+ : 5 I 7 level in the transparent glass–ceramic was longer than that of precursor glass. The split in the absorption and emission bands and the reduction of the Ω 2 parameter for the glass–ceramic confirmed the incorporation of Ho 3+ ions into the crystalline phase. The results indicate that TeO 2 -based glass–ceramics are a promising candidate material for 2-μm lasers. [ABSTRACT FROM AUTHOR]

A Ho 3+ -doped silica glass, 0.08Ho 2 O 3 –1.6Al 2 O 3 –98.32SiO 2 (mol%), was prepared by the sol–gel method combined with high temperature sintering. The 2 μm luminescence properties of the Al 3+ /Ho 3+ co-doped silica core glass were investigated. A single-mode double cladding Al 3+ /Ho 3+ co-doped silica fiber with a 15 μm core diameter and 0.08 core numerical apertures was prepared. Pumped with a 1.95 μm Tm 3+ fiber laser, 320 mw laser output centered at 2040 nm with M 2 factor of 1.14 was obtained from a 150-cm-long double-cladding fiber. The laser has a threshold of 850 mw launched power with a slope efficiency of 48.46%. For the first time a robust single-mode 2 μm fiber laser was realized in a fiber with Al 3+ /Ho 3+ co-doped silica core glass prepared by the sol–gel method. [ABSTRACT FROM AUTHOR]

Abstract: A novel Tm3+-doped lead silicate glass with good thermal stability was prepared in this work. Through thorough investigation of 2µm luminescent properties of the glasses, optimal Tm2O3 doping concentration was checked to be 3wt%. Double cladding fiber was prepared by stacking method. As a result, 2µm laser output was realized in a 40cm fiber and the maximum output power reached 70mw. [Copyright &y& Elsevier]