Germanium Oxide Glass Research Articles

Influence of Al2O3 on the photoluminescence and optical gain performance of Nd3+ doped germanate and tellurite glasses

Abstract We investigated the influence of aluminum oxide, Al2O3, on the photoluminescence (PL) spectrum and optical gain (at 1064 m) of neodymium ion, Nd3+, doped tellurium and germanium oxide glasses with compositions TeO2 − ZnO and GeO2 − PbO, respectively. The PL properties of both materials were studied using a continuous-wave diode laser operating at 808 nm, in resonance with the Nd3+ transition 4I9/2 → 4F5/2. For samples containing Al2O3 it was observed PL intensity growth up to 30% in comparison with the samples without Al2O3. Luminescence decay (τm) from the 4F3/2 level was measured monitoring the 4F/32 → 4I11/2 transition. From calculations of the Judd–Ofelt parameters, the radiative lifetimes, the emission cross -section (σem) and the quantum efficiency of 4F3/2 → 4I11/2 transition were determined; the effective linewidth (Δλeff) was calculated to determine the gain bandwidth product (σem x Δeff), figure of merit (σem x τm) and saturation intensity (Is) parameters. Optical gain measurements were performed using a pump laser at 808 nm and a probe laser at 1064 nm. For the samples with Al2O3 the relative gain at 1064 nm reached ≈ 2.8 dB/cm (pump laser power: 400 mW) indicating an enhancement of about 65% for TeO2 − ZnO and 120% for GeO2 − PbO with respect to the samples without Al2O3. The optical gain enhancement is correlated to the PL intensity behavior and increases due to the presence of Al2O3 because the coordination environment of the Nd3+ changes and become more asymmetric leading to the growth of the emission cross-section. The present study shows that Nd3+ doped tellurium and germanium oxide glasses containing Al2O3 present particularly good prospects to be used as optical amplifiers at 1064 nm.

Crystallization of GeO2–Al2O3–Bi2O3 Glass

In the presented work, two kinds of germanium oxide glass with different compositions, namely GeO2 and GeO2–Al2O3–Bi2O3, were investigated. After controlled crystallization of a glassy sample, the emission in the NIR-range was determined (1165 nm with excitation at 470 nm). To better understanding the kinetics of the glass crystallization, the activation energy was also determined by applying the Kissinger method. The obtained results show that in the case of GeO2–Al2O3–Bi2O3, activation energy value was 400 and 477 kJ/mol, which means that such values are significantly larger than for pure GeO2 (254 kJ/mol). The investigations also show that two phases crystallized in the complex glass matrix: the mullite-like phase and germanium oxide.

Density of amorphous GeO2 to 133 GPa with possible pyritelike structure and stiffness at high pressure

Germanium oxide is a prototype network-forming oxide with pressure-induced structural changes similar to those found in crystals and amorphous silicate oxides at high pressure. Studying density and coordination changes in amorphous $\mathrm{Ge}{\mathrm{O}}_{2}$ allows for insight into structural changes in silicate oxides at very high pressure, with implications for the properties of planetary magmas. Here, we report the density of germanium oxide glass up to 133 GPa using the x-ray absorption technique, with very good agreement with previous experimental data at pressure below 40 GPa and recent calculation up to 140 GPa. Our data highlight four distinct compressibility domains, corresponding to changes of the local structure of $\mathrm{Ge}{\mathrm{O}}_{2}$. Above 80 GPa, our density data show a compressibility and bulk modulus similar to the counterpart crystal phase, and we propose that a compact distorted sixfold coordination, similar to the structural motif of the pyritelike crystalline $\mathrm{Ge}{\mathrm{O}}_{2}$ polymorph, is likely to be stable in that pressure range. Our density data point to a smooth continuous evolution of the average coordination for pressure above 20 GPa with persistent sixfold coordination, without sharp density or density slope discontinuities. These observations are in very good agreement with theoretical calculations and spectroscopic measurements, and our results indicate that glasses and melts may behave similarly to their high-pressure solid counterparts with comparable densities, compressibility, and possibly average coordination.

Synthesis and nuclear radiation shielding characterization of newly developed germanium oxide and bismuth oxide glasses

We present the synthesis and nuclear radiation shielding characterization of glasses based on germanium and bismuth oxide prepared with the melt-quenching technique. The glasses were produced using six different compositions as follows (in wt%): 40.0GeO2-60.0PbO, 38.0GeO2-62.0Bi2O3, 31.344GeO2-41.900Bi2O3-26.756PbO, 33.334GeO2-33.333TeO2-33.333PbO, 20.6GeO2-41.9TeO2-17.4Nb2O5-20.1BaO, 41.98Bi2O3-48.26PbO-8.10Ga2O3-1.66BaO. Monte Carlo method (MCNPX code, v-2.6.0) has been utilized for the determination of mass attenuation coefficients (μ/ρ) of the synthesised six different glasses. The acquired mass attenuation coefficients (μ/ρ) have been used to determine the vital parameters for gamma-ray shielding namely half value layer (HVL), mean free path (MFP), tenth value layer (TVL), effective atomic number (Zeff), exposure buildup factor (EBF), energy absorption buildup factor (EABF), transmission factors (TF), respectively. Simultaneously, effective removal cross section (∑R) values for fast neutrons and Proton mass stopping power & proton projected range have been also calculated. The results showed that among all the investigated glasses, 41.98Bi2O3-48.26PbO-8.10Ga2O3-1.66BaO glass sample has the extra capability to reduce nuclear radiation as a shielding material.

Germanium oxide glass based metal-dielectric nanocomposites: fabrication and optical characterization: a review of new developments

We review recent experimental results with germanate glasses containing rare-earth ions (RE) and silver nanoparticles (Ag-NPs) nucleated by appropriate heat-treatment of samples. In one study, the photoluminescence (PL) due to an infrared-to-visible frequency upconversion (UC) process was investigated in Bi2O3–GeO2 (BGO) glasses co-doped with ytterbium (Yb3+) and erbium (Er3+) ions when low concentration of AgNO3 was added to the starting glass composition. By exciting the samples at 980 nm, in resonance with the Yb3+ transition, we investigated the influence of the Ag-NPs on the UC process. The Er3+ PL was enhanced, up to 100%, due to the increased local-field sensed by the RE and to the efficient Yb3+ → Er3+ energy-transfer. In another set of experiments, we studied the behavior of BGO glasses containing thulium ions (Tm3+) and Ag-NPs. The role of energy-transfer from bismuth centers to Tm3+ was investigated. PL and relative gain enhancements of ≈ 56% and 500%, respectively, were observed due to the influence of Ag-NPs. Using a pump laser operating at 808 nm (6 W) and a probe laser at 1470 nm (0.6 mW) the relative gain measured at 1470 nm was 4.5 dB/cm. The results from the two sets of experiments indicate that Yb3+/Er3+ co-doped BGO glass with Ag-NPs is an efficient upconverter and Tm3+ doped BGO glass with Ag-NPs can be used as efficient optical amplifier in the short-wave infrared region.

飞秒激光直写实现氧化锗玻璃内部光调制

飞秒激光直写实现氧化锗玻璃内部光调制

Oxygen Packing Fraction and the Structure of Silicon and Germanium Oxide Glasses.

The recently proposed relationship between the oxygen volume fraction and topological ordering in solid and liquid oxide glasses at high pressure is examined with Bader's atoms-in-molecules (AIM) theory using glass structures generated from first principles molecular dynamics calculations. It is shown that the atomic (O/Si and O/Ge) volume ratio derived from AIM theory is not constant with pressure. This finding is due to the continuous change in the electron topology under compression. Unlike crystalline solids, there is no distinctive transition pressure for Si-O and Ge-O coordination in a glass; instead, the changes are gradual and continuous over a broad pressure range. Therefore, relating a unique Si-O or Ge-O coordination number to the properties of the glass at a given pressure is difficult.

Novel Bi-doped glasses for broadband optical amplification

Broadband infrared luminescence is observed in various Bi-doped oxide glasses prepared by conventional melting-quenching technique. The absorption spectrum of the Bi-doped germanium oxide glass consists of five broad peaks at below 370, 500, 700, 800 and 1000 nm. The fluorescence spectrum exhibits a broad peak at about 1300 nm with full width at half maximum (FWHM) of more than 300 nm when excited by an 808 nm laser diode. The fluorescence lifetime at room temperature decreases with increasing Bi2O3 concentration. Influence of the glass composition and melting atmosphere on the fluorescence lifetime and luminescent intensity is investigated. The mechanism of the broadband infrared luminescence is suggested. The product of stimulated emission cross-section and lifetime of the Bi-doped aluminophosphate glass is about 5.0 X 10(-24) cm(2) s. The glasses might be promising for applications in broadband optical fiber amplifiers and tunable lasers. (c) 2007 Elsevier B.V. All rights reserved.

Superbroadband 1310 nm emission from bismuth and tantalum codoped germanium oxide glasses

Near-infrared broadband emission from bismuth-tantalum-codoped germanium oxide glasses was observed at room temperature when the glasses were pumped by an 808 nm laser diode. The emission band covered the O, E, S, C, and L bands (1260-1625 nm), with a maximum peak at approximately 1310 nm, a FWHM broader than 400 nm, and a lifetime longer than 200 micros. The observed broadband luminescence was attributed to bismuth clusters in the glasses. Bismuth-tantalum-codoped germanium oxide glass might be promising as amplification media for broadly tunable lasers and wideband amplifiers in optical communications.

Investigations on bismuth and aluminum co-doped germanium oxide glasses for ultra-broadband optical amplification

The broadband luminescence covering 1.2–1.6 μm was observed from bismuth and aluminum co-doped germanium oxide glasses pumped by 808 nm laser at room temperature. The spectroscopic properties of GeO 2:Bi,Al glasses strongly depend on the glass compositions and the pumping sources. To a certain extent, the Al 3+ ions play as dispersing reagent for the infrared-emission centers in the GeO 2:Bi,Al glasses. The broad infrared luminescence with a full width at half maximum larger than 200 nm and a lifetime longer than 200 μs possesses these glasses with the potential applications in broadly tunable laser sources and ultra-broadband fiber amplifiers in optical communication field.

Bismuth- and aluminum-codoped germanium oxide glasses for super-broadband optical amplification.

Broadband infrared luminescence from bismuth-doped germanium oxide glasses prepared by a conventional melting-quenching technique was discovered. The absorption spectrum of the glasses covered a wide range from the visible to the near-infrared wavelength regions and consisted of five broad peaks below 370, 500, 700, 800, and 1000 nm. The fluorescence spectrum exhibited broadband characteristics (FWHM) greater than 300 nm with a maximum at 1300 nm pumped by an 808-nm laser. The fluorescence lifetime at room temperature decreased with increasing Bi2O3 concentration in the glass. Codoping of aluminum and bismuth was indispensable for the broadband infrared luminescence in GeO2:Bi, Al glass.

Fabrication and Ultraviolet Absorption of Sol–Gel‐Derived Germanium Oxide Glass Thin Films

Germanium oxide glass thin films were prepared by the sol–gel method and annealed under reduced atmosphere to create more oxygen‐deficient defects. The densification and crystallization were examined depending on sintering and annealing conditions. Thus, homogeneous germanium oxide thin films with a high content of oxygen vacancies were fabricated. Ultraviolet absorption and oxygen vacancies of the films were investigated as a function of annealing temperature and time. Optical absorption in the 5‐eV region due to the formation of oxygen vacancies is enhanced with increasing annealing temperature and time. The formation energy of oxygen vacancies is calculated to be about 1.0 eV.

Photobleaching of sol-gel-derived germanium oxide glass thin films

Photobleaching of the optical absorption band in the 5-eV region of sol-gel-derived germanium oxide glass thin films was examined with the irradiation of the 5-eV light. The photobleaching represented by the saturated absorption coefficient change (−Δα) and the ratio of the neutral oxygen monovacancies to neutral oxygen divacancies concentrations for the germanium oxide were 175 cm−1 and 0.113, respectively. These values are larger than those of the pure germanium oxide bulk glass as well as germanosilicate thin films. The changes in bonding configuration around Ge atom by ultraviolet illumination were analyzed using x-ray photoelectron spectroscopy.

Photosensitivity of germanium oxide and germanosilicate glass sol–gel films

Germanium oxide and germanosilicate glass films were fabricated using a sol–gel spin coating method. The formation and photobleaching of the optical absorption band of the films in the 5-eV region were measured as a function of annealing under a reducing atmosphere and ultraviolet (UV) illumination. A greater amplitude in the 5-eV absorption band was observed with increasing annealing time due to the formation of more germanium-related oxygen vacancies in the films. Also, the photobleaching of the absorption band increased with increasing illumination time. Although the amplitude of the absorption band in 50GeO 2–50SiO 2 glass films is greater than that in germanium oxide glass films because of higher annealing temperature, germanium oxide glass films are more photosensitive due to the greater photobleachable neutral oxygen monovacancy (NOMV) concentration than non-photobleachable neutral oxygen divacancy (NODV) concentration in the films.

Bulk and Surface Crystallization in SrO-doped Germanium Oxide Glass

Bulk and Surface Crystallization in SrO-doped Germanium Oxide Glass

A germanium-oxide glass optical fiber prepared by a VAD method

Loss values of 4 dB/km at 2 μm and 15 dB/km at 2.4 μm were obtained for an antimony-doped germanium-oxide glass optical fiber prepared by a VAD method incorporating a dehydration process.

Germanium-oxide glass optical fibre prepared by VAD method

Germanium-oxide glass optical fibre doped with antimony for transmission of the 2 to 3 ?m band has been prepared by the vapour-phase axial deposition (VAD) method. An attenuation loss of 13 dB/km at 2.05 ?m and 70 dB/km at 2.4 ?m has been achieved.