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One dimensional pattern of 500 nm period was formed on a soda-lime silicate glass by the electrical nanoimprint below the glass transition temperature. The imprinted glass surface was analyzed using a transmission electron microscopy and an energy-dispersive X-ray spectroscopy with the cryogenic system. The concentrated parabolic layers of Ca 2 + and Mg 2 + were formed separately in the Na + deficient layer. The deficient area both of such alkali and alkaline-earth cations was preferentially removed in an alkali etchant, resulting the enhancement of the aspect ratio of the one-dimensional relief pattern. Therefore, the distribution control of alkaline-earth cations was important for the fabrication of sub-micron scale patterns with high aspect ratio on the glass surface.

X-ray photoelectron spectroscopy with C 60 -ion sputtering (C 60 -XPS) and electron spin resonance (ESR) revealed the migration behavior of network-modifier cations in an electrically poled soda-lime silicate glass. The Na + -deficient layer of 700-nm thickness was confirmed at the anode side surface. The Mg 2 + and Ca 2 + existed in the 200-nm thick layer from the top surface were concentrated in the layer of 200–700 nm depth from the surface. Additionally the oxygen content in the 200-nm thick layer decreased by the degassing as oxygen molecules from the glass surface, which is an essential requirement for the migration of Mg 2 + and Ca 2 + to cathode side. The bond scission between Si–O–Si is caused by the concentrated Mg 2 + and Ca 2 + , resulting the formation of SiO − (Mg 2 + or Ca 2 + ) − OSi and Si· (Si E′ center). We have also confirmed the generation of oxygen hole center (NBOHC) and peroxy radical (POR) in the electrically poled soda-lime silicate glass.

The effects of the substitution of fluoride ions for oxide ions on the thermal and optical properties of ternary ZnO-Bi 2 O 3 -P 2 O 5 glass with low-P 2 O 5 content (20–25 mol%) were investigated. Fluoride ions were introduced into the glass up to about 12 mol% as ZnF 2 . Raman spectra indicated that fluoride ions were substituted for oxide ions connected with bismuth ions. Deformation and glass transition temperatures decreased monotonically with fluorine concentration. The absorption edge shifted toward higher energies with increasing fluorine concentration by about 0.3 eV for 12 mol% ZnF 2 substitution. The blue shift of the absorption edge is attributable to two effects. One was a blue shift of an absorption band which was observed as a peak at 4.7 eV in the reflection spectra and was attributed to the spin forbidden 6s–6p interband transition in Bi 3+ ions. The blue shift originates from a change in electron-donating ability through anions as expected from electronegativity or optical basicity. Another is a disappearance of a shoulder at around 4.3 eV in the reflection spectra. The latter was the major reason for the large blue shift of the absorption edge energy, because the band relating to the 4.3 eV shoulder is close to the absorption edge.

We have studied the temperature coefficient of the refractive index of synthetic silica glasses with various hydroxyl impurities. The refractive index was measured at 15 °C and 35 °C at 1.707–0.238 μm wavelengths. The temperature coefficient of a low-OH group (110 wt. ppm) containing glass increased from 8.0 ± 0.2 × 10−6/°C (at 1.707 μm) to 14.0 ± 0.2 × 10−6/°C (at 0.238 μm), although it increased respectively from 7.0 ± 0.2/°C to 12.0 ± 0.2 × 10−6/°C for a high-OH group (1300 wt. ppm) containing glass. The three-term Sellmeier equation, having two terms with resonance photon energies in the vacuum ultraviolet region and one term in the infrared region, was used to analyze the wavelength dispersion of the refractive index. Increasing temperatures shifted the resonance energy in the second term by −4.14 ± 0.4 × 10−4 eV/°C for low-OH (110 wt. ppm) glass and −2.64 ± 0.4 × 10−4 eV/°C for high-OH (1300 wt. ppm) glass. The fundamental absorption edge in the vacuum ultraviolet region shifted by −8.8 ± 0.7 × 10−4 eV/°C for the low-OH glass and −6.3 ± 0.7 × 10−4 eV/°C for the high-OH glass in a region of 25–100 °C. Both high-OH glass shift rates were lower than low-OH glass shift rates. The lower temperature coefficient for the Si–OH-related band probably explains the smaller temperature coefficient for high-OH glass: the absorption band of Si–O–H structure is located at lower energy side close to the fundamental absorption band associated with the Si–O–Si structure.

Reduction in the temperature coefficient of the optical path length, d S /d T of Li 2 O–Al 2 O 3 –SiO 2 glass–ceramics with near-zero thermal expansion coefficient was attempted using control of the temperature coefficient of electronic polarizability, ϕ , and the thermal expansion coefficient, α . The d S /d T value of 2.6 mol% B 2 O 3 -doped glass–ceramic was 12.5 × 10 −6 /°C, which was 0.9 × 10 −6 /°C smaller than that of B 2 O 3 -free glass–ceramic. On the other hand, reduction in d S /d T through B 2 O 3 doping was not confirmed in precursor glasses. Results showed that reduction in d S /d T of the glass–ceramic through B 2 O 3 doping is caused by the reduction in ϕ . The reduction in ϕ from B 2 O 3 doping was probably attributable to numerical reduction in non-bridging oxide ions with larger ϕ value by the concentration of boron ions in the residual glass phase. In addition, application of hydrostatic pressure during crystallization was effective to inhibit precipitation of β -spodumene solid solution, which thereby decreases d S /d T . The d S /d T value of B 2 O 3 -doped glass–ceramic crystallized under 196 MPa was 11.7 × 10 −6 /°C. That value was slightly larger than that of silica glass. The α value of this glass–ceramic was smaller than that of silica glass.

The photoluminescence spectra of the divalent Ge (Ge2+) center in GeO2–SiO2 glasses with different photosensitivities were investigated by means of excitation-emission energy mapping to correlate the ultraviolet light induced photorefractivity with the local structure around the Ge2+ centers. The glasses with a larger photorefractivity tended to exhibit a greater band broadening of the singlet–singlet transition to higher excitation energies accompanied by an increase in the Stokes shifts. This strongly suggests the existence of a highly photosensitive Ge2+ centers with higher excitation energies. It was also found that the introduction of a hydroxyl group or boron species modifies the local environment of Ge2+ leading to an enhanced photorefractivity.

Ge–SiO2 thin glass films photosensitive to excimer laser irradiation were fabricated by plasma enhanced chemical vapor deposition. A channel waveguide was successfully fabricated by irradiation with only an excimer laser through a Cr mask pattern, which was previously coated on the slab-waveguide by the sputtering method. Bragg gratings with high diffraction efficiency were also fabricated in the waveguide by another KrF laser irradiation through the phase mask without hydrogen loading. Channel waveguides with Bragg gratings, on the other hand, were fabricated on the glass ceramic substrates with negative thermal expansion coefficient. Doping of the B2O3 to Ge–SiO2 glass film effectively suppressed the temperature drift of the stop band (dλ/dT) of the gratings. The dλ/dT attained in this study was 4 pm/°C, which was less than one-third of those reported for commercially available waveguide gratings. Although the grating printed in the Ge–B–SiO2 film was almost erased by annealing at a temperature lower than 500 °C, a new type of grating with much higher diffraction efficiency than that before annealing was formed after annealing at 600 °C. The diffraction efficiency of the new grating was unchanged after repeated heating between room temperature and 600 °C.

Germanosilicate glasses (10GeO2–90SiO2) were prepared by a sol–gel method and the ultraviolet-photosensitivity of glasses was investigated by optical absorption, electron spin resonance, and photoluminescence measurements. A one order larger intensity in the 5-eV absorption band was observed in the sol–gel glass sintered under an atmosphere at pressure 5.7 eV were also noted. Photoluminescence intensity under 248-nm excitation decreased with an increase in laser fluence and with a corresponding decrease in the 5-eV band. This result implies that an ultraviolet-induced photochemical reaction from Ge2+ to Ge E′ in the glass had occurred.

High pressure effects on optical properties of Ce3+ doped ternary fluoroaluminate (18BaF2·37CaF2·45AlF3) glass have been investigated in terms of ligand field around cerium ion. Five bands due to the 4f–5d transitions were observed in ultraviolet absorption spectra for the glass. A photoluminescence band was observed at around 300 nm under excitation at each band. The photoluminescence band shifted toward smaller energies by densifying the glass using high pressures and temperatures. An energy shift of the band was also found in in situ photoluminescence measurement under high pressure using a sapphire anvil cell. However, the shift observed under high pressure was large compared with that of the densified glass. We deduced that the large peak shift under high pressure is mainly due to a local elastic contraction around cerium ion.

Permanent, positive refractive-index changes in pure GeO 2 glass slabs are induced by illumination with light having energy far below that of the fundamental absorption edge. The refractive-index change is tentatively explained by the Kramers–Kronig relationship for an additional absorption band induced in the glass via two competitive photochemical reactions.

Solubilities of platinum group metals (Pd, Rh, Pt) in several glasses were investigated by the use of optical absorption measurements. The concentrations of these ions in the glasses were determined by chemical analysis. The absorption cross-sections of the ions were determined by relating the absorption coefficient and the analyzed concentration. Using these cross-sections, the solubilities of these ions in multicomponent glasses were investigated. It was found that solubilities of these metals are < 100 ppm in soda-lime-boro-silicate and soda-lime-alumino-boro silicate glasses. Also found was their volatility during melting. Light scattering measurements were also carried out to obtain information on the existence of metal particles. It was found that a considerable fraction of Pt exists as metal particles in soda-lime-alumino-boro-silicate glasses.

Sulfide, selenide and telluride glass fibers were prepared for infrared optical applications. A new crucible drawing method was developed for the drawing of fibers with glass cladding. The extrinsic losses caused by some oxide impurities were suppressed by the purification of raw elements. The transmission loss and mechanical strength, i.e., bending and tensile, of each fiber were investigated before and after the heat treatment under humid conditions. The fibers obtained were used for the power delivery of CO2 laser (10.6 μm) and CO laser (5.4 μm). The antireflection coating onto fiber ends and cooling of fiber with gas or water were examined for the improvement of power transmission efficiency. A fiber cable having ZnSe lens at the output end was prepared for medical and other applications. Temperature monitoring, thermal imaging and gas sensing were also tried using the fibers.

Transmission loss spectra of Ge-Se-Te and Ge-Se-Te-Tl unclad glass fibers were measured in a wavelength region between 2 and 13μm. Raw materials were purified by the H 2 reduction for Ge and Tl and by the distillation for Se and Te. The minimum loss of the Ge-Se-Te fibers was 0.6dB/m at 8.2μm(1.5dB/m at 10.6μm) where the glass composition was Ge27Sel8Te55. Although the introduction of Tl above 4mol % increased the intrinsic absorption loss, the best result of 1.0dB/m at 9.0μm(1.5dB/m at 10.6μm) was achieved for Ge 25 Se 13 Te 60 Tl 2 glass fiber.

On a observe la formation de verres dans le systeme AgI-CsI et la vitrification est fortement amelioree par la substitution partielle de l'iodure par le bromure et l'addition de faibles quantites de PbBr 2

Demolding behavior of oxide glasses from molds was experimentally analyzed using a specially developed molding set up equipped with highly sensitive load cell and servomotor. The demolding point and the demolding force were apt to increase with the tensile force applied to the pressing axis, and also to the cooling rate. Especially the demolding force was strongly affected by the cooling rate when the demolding point was located near the glass transition temperature region. These results offer a useful direction for highly accurate glass-molding and glass-imprint processes. (C) 2013 Elsevier B.V. All rights reserved.