germanium and gallium-oxide

Nanoparticles in amorphous oxides are a powerful tool for embedding a wide range of functions in optical glasses, which are still the best solutions in several applications in the ever growing field of photonics. However, the control of the nanoparticle size inside the host material is often a challenging task, even more challenging when detrimental effects on light transmittance have to be avoided. Here we show how the process of phase separation and subsequent nanocrystallization of a Ga-oxide phase can be controlled in germanosilicates - prototypal systems in optical telecommunications - starting from a Ga-modified glass composition designed to favour uniform liquid-liquid phase separation in the melt. Small angle neutron scattering data demonstrate that nanosized structuring occurs in the amorphous as-quenched glass and gives rise to initially smaller nanoparticles, by heating, as in a secondary phase separation. By further heating, the nanophase evolves with an increase of nanoparticle gyration radius, from a few nm to a saturation value of about 10 nm, through an initial growing process followed by an Ostwald ripening mechanism. Nanoparticles finally crystallize, as indicated by transmission electron microscopy and X-ray diffraction, as γ-Ga(2)O(3)- a metastable gallium oxide polymorph. Infrared reflectance and photoluminescence, together with the optical absorption of Ni ions used as a probe, give an indication of the underlying interrelated processes of the structural change in the glass and in the segregated phase. As a result, our data give for the first time a rationale for designing Ga-modified germanosilicates at the nanoscale, with the perspective of a detailed nanostructuring control.

Topics: Crystallization; Equipment Design; Gallium; Germanium; Glass; Lenses; Materials Testing; Nanostructures; Particle Size; Refractometry; Silicates; Surface Properties

The 2.7 μm emission properties in Er3+-doped bismuthate (Bi2O3-GeO2-Ga2O3-Na2O) glass were investigated in the present Letter. An intense 2.7 μm emission in Er3+-doped bismuthate glass was observed. It is found that Er3+-doped bismuthate glass possesses high spontaneous transition probability A (65.26 s(-1)) and large 2.7 μm emission cross section σ(em) (9.53×10(-21) cm2) corresponding to the stimulated emission of Er3+:4I11/2→4I13/2 transition. The emission characteristic and energy transfer process upon excitation of a conventional 980 nm laser diode in bismuthate glass were analyzed. Additionally, the structure of bismuthate glass was analyzed by the Raman spectrum. The advantageous spectroscopic characteristics of Er3+ single-doped bismuthate glass together with the prominent thermal property indicate that bismuthate glass might become an attractive host for developing solid-state lasers around 2.7 μm.

Topics: Absorption; Bismuth; Erbium; Gallium; Germanium; Glass; Oxides; Sodium Compounds; Spectrophotometry, Infrared; Spectrum Analysis, Raman

The Eu(3+) ion was introduced into Er(3+) doped Bi(2)O(3)-GeO(2)-Ga(2)O(3)-Na(2)O (BGGN) glasses to improve the 1.5 microm band emission. As a function of Eu(2)O(3) doped content, we observed the increase in non-radiative decay rate of Er(3+) not only (4)I(11/2) energy level but also (4)I(13/2) energy level, while the lifetime of Er(3+):(4)I(11/2) and (4)I(13/2) levels were shortened from 607 to 241 micros and from 3.37 to 1.88 ms, respectively. Accordingly, the upconversion fluorescence (green and red) was quenched. The total quantum efficiency of the Er(3+):(4)I(13/2) increased with the Eu(2)O(3) content increasing up to 0.2 mol% due to the state-selective energy transfer from Er(3+) to Eu(3+).

Topics: Absorption; Bismuth; Energy Transfer; Erbium; Europium; Fluorescence; Gallium; Germanium; Glass; Oxides; Sodium Compounds

The absorption spectra and upconversion fluorescence spectra of Er3+/Yb3+-codoped natrium-gallium-germanium-bismuth glasses are measured and investigated. The intense green (533 and 549 nm) and red (672 nm) emission bands were simultaneously observed at room temperature. The quadratic dependence of the green and red emission on excitation power indicates that the two-photon absorption processes occur. The influence of Ga2C3 on upconversion intensity is investigated. The intensity of green emissions increases slowly with increasing Ga2O3 content, while the intensity of red emission increases significantly. The possible upconversion mechanisms for these glasses have also been discussed. The maximum phonon energy of the glasses determined based on the infrared (IR) spectral analysis is as low as 740 cm-1. The studies indicate that Bi2O3-GeO2-Ga2O3-Na2O glasses may be potential materials for developing upconversion optical devices.

Topics: Bismuth; Erbium; Gallium; Germanium; Glass; Oxides; Sodium Compounds; Spectrometry, Fluorescence; Spectrophotometry, Ultraviolet; Ytterbium