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Ge-As-Ga-S glasses codoped with Er[sup 3+] and Pr[sup 3+] were synthesized for fiber-optic amplifiers operating in both 1.3 and 1.5 µm communication windows. The energy transfer between Er[sup 3+] and Pr[sup 3+] in Ge-As-Ga-S glasses was analyzed quantitatively using rate equations. The energy transfer coefficients responsible for two different energy transfer routes were 2.2(±0.05)x10[sup -18] (Er[sup 3+]:[sup 4]I[sub 1 1/2]→Pr[sup 3+]:[sup 1]G[sub 4]) and 5.6(± 0.05) x 10[sup -17] s[sup -1] cm³ (Er[sup 3+]:[sup 4]I[sub 13/2]→Pr[sup 3+]:[sup 3]F[sub 4,3]), respectively. The former transfer process enhanced amplification efficiency in 1.3 µm band, while the latter reduced efficiency in the 1.5 µm band. Numerical simulation of the amplification characteristics demonstrated that signal gains of 30 and 40 dB were possible in 1.3 and 1.5 µm bands, respectively. [ABSTRACT FROM AUTHOR]

Efficient persistent spectral hole burning in Eu[sup 3+]-doped sulfide glasses was observed with the addition of CsBr or KBr. Holes in these glasses showed high initial growth rates, thermal barrier heights, and low relaxation rates. It was also possible to form independent multiholes on the inhomogeneously broadened absorption spectrum. One-photon absorption of the burning light and corresponding reduction of Eu[sup 3+] into Eu[sup 2+] via interaction with local conduction (or charge transfer) bands are the main processes for hole burning. [ABSTRACT FROM AUTHOR]

A low sintering temperature glass based on the SiO2-P2O5-ZnO-B2O3-R2O (R=K and Na) system was studied as a matrix for embedding phosphors to fabricate color tunable white LEDs. The proposed system, which uses no heavy-metal elements and can be sintered at 500°C, incorporates thermally weak commercial phosphors such as CaAlSiN3:Eu2+ to produce phosphor-in-glasses (PiGs). Changing the mixing ratio of glass to phosphors affected the photo-luminescence spectra and color coordinates of the PiGs when mounted on a blue LED. The color rendering index (CRI) and color correlated temperature (CCT) of the LEDs were also varied with the mixing ratio, providing color tunable white LEDs. A high CRI, up to 93, as well as highly improved thermal stability were obtained, along with a low sintering temperature compared to other glass systems, suggesting the practical feasibility of the proposed system. [ABSTRACT FROM AUTHOR]

The influence of Nd3+ ions was investigated on the precipitation and optical properties of PbS quantum dots ( QDs) inside silicate glasses. The diameters of the PbS QDs decreased as the concentration of Nd3+ in the glass increased as evidenced by blue shifts in the absorption and photoluminescence spectra. Electron energy loss spectroscopy shows that Nd3+ ions exist preferentially inside the PbS nanocrystals rather than in the glass matrix. We postulate that Nd-O clusters are preserved during heat treatment and serve as nucleation sites for PbS crystals. No change in the local bonding scheme of the Nd3+ ions was observed following heat treatment. [ABSTRACT FROM AUTHOR]

This article reports the effect of Ag+ ion-exchange on the precipitation of PbS quantum dots ( QDs) in silicate glasses. The glasses were subjected to ion-exchange in AgNO3 salt melts at 260°C for 60 s. Ag nanoparticles ( NPs) and PbS QDs precipitated after heat treatment at temperatures of 440°C-460°C for 10 h. Photoluminescence wavelength λPL of PbS QDs was longer (~1525 ≤ λPL ≤ ~1580 nm) in Ag+ ion-exchanged regions than in Ag+-free regions (~1030 ≤ λPL ≤ ~1200 nm). Average diameter D of PbS QDs estimated by calculation and TEM images was larger in Ag+ ion-exchanged regions (~5.2 ≤ D ≤ ~5.5 nm) than in Ag+-free regions (~2.4 ≤ D ≤ ~3.3 nm). Ag NPs that formed during heat treatment provided the sites for heterogeneous nucleation of PbS QDs and promoted the precipitation of PbS QDs in glasses. [ABSTRACT FROM AUTHOR]

Abstract: We experimentally verify that a color center in the form of takes shape in silicate glasses containing relatively small amount of ZnSe which are prepared via a conventional melt-quenching process. Samples also produce broad photoluminescence when excited with UV light source, suggesting potential applications in the visible range. Analyses based on X-ray diffraction patterns, high resolution transmission electron microscopy, and Raman spectroscopy support the formation of color centers in addition to Se nanocrystals. [Copyright &y& Elsevier]

PbS and PbS/CdS core/shell colloidal quantum dots (QDs) were mixed with As 2 S 3 glass powders to prepare solid composite materials. PbS QDs showed an absorption band centered at a wavelength of λ = 1478 nm and a photoluminescence (PL) band centered at λ = 1547 nm. PbS/CdS core/shell QDs had higher PL intensity than did bare PbS QDs. Solid composites made by mixing QDs and As 2 S 3 glass powders showed clear PL bands at λ = 1385 nm. Optical fibers of As 2 S 3 glass can be prepared from these composite materials if appropriate scale-up technology is realized. [ABSTRACT FROM AUTHOR]

Emission properties and energy transfer of PbO-Bi2O3-Ga2O3-GeO2 glasses codoped with Tm3+ and Tb3+ ions were investigated. The 1.48-μm emission due to the Tm3+ : ³H4→³F4 transition can be used to amplify the S-band (1460-1530-nm) signal light. With Tb3+ addition, the lifetime and emission intensity of the Tm3+ : ³F4 level decreased sharply via the Tm3+ : ³F4 → Tb3+ : 7 F0.12 energy transfer. Population densities of the ³F4 and ³H4 levels in Tm3+ calculated from rate equations clearly verified that population inversion in Tm3+ ions became possible with as little as 0.1 mol% of Tb3+ addition. [ABSTRACT FROM AUTHOR]

Emission properties and energy transfer of PbO-Bi2O3-Ga2O3-GeO2 glasses codoped with Tm3+ and Tb3+ ions were investigated. The 1.48-μm emission due to the Tm3+ : ³H4→³F4 transition can be used to amplify the S-band (1460-1530-nm) signal light. With Tb3+ addition, the lifetime and emission intensity of the Tm3+ : ³F4 level decreased sharply via the Tm3+ : ³F4 → Tb3+ : 7 F0.12 energy transfer. Population densities of the ³F4 and ³H4 levels in Tm3+ calculated from rate equations clearly verified that population inversion in Tm3+ ions became possible with as little as 0.1 mol% of Tb3+ addition. [ABSTRACT FROM AUTHOR]

PbS QDs of ~ 5nm diameter were precipitated in glasses containing Ag nanoparticles after 3 min of 1.5-W continuous-wave laser illumination at λ = 532 nm. Photoluminescence spectra of the PbS QDs recorded in the 1.3~1.6 μm wavelength region revealed conversion of photon energy to thermal energy by surface plasmon resonance. Laser-assisted local heating around Ag NPs can provide a new method to control the spatial distribution of QDs in glasses. [ABSTRACT FROM AUTHOR]

Precipitation of PbS quantum dots (QDs) in glasses was controlled by thermal diffusion of Ag+ ions from Ag paste at a temperature of 320°C. After subsequent heat treatment at 420–450°C, PbS QDs formed in the near-surface regions where the silver paste was applied. After the glasses were heat-treated at 440 or 450°C, PbS QDs were larger in Ag-affected surface regions than in Ag-free glasses. PbS QDs grew in Ag-affected regions when they were heat-treated at 420 or 430°C. Ag+ ions penetrated ~25μm from the glass surface after thermal diffusion of Ag+ ions and subsequent heat treatment at 430°C. Thermal diffusion of Ag+ ions from Ag paste is a viable method to control the precipitation and spatial distribution of PbS QDs in glasses. [ABSTRACT FROM AUTHOR]

Abstract: Electric-field assisted solid-state diffusion of Ag+ was used to control precipitation of PbS quantum dots (QDs) inside glasses. Precipitation of PbS QDs was confirmed by transmission electron microscopy images and photoluminescence (PL) spectra. PL bands moved to longer wavelengths as applied voltage increased under the same subsequent heat-treatment, and as heat-treatment temperature increased under the same voltage. PbS QDs can preferentially precipitate at low temperature and photo-luminesce at longer wavelengths in Ag+-affected regions than in unaffected regions. Ag nanoparticles were also formed inside affected regions after thermal treatment, and provided nucleation sites for PbS QDs. Precipitation of PbS QDs and their spatial distribution in glasses can be controlled by electric field-assisted Ag+ migration. [Copyright &y& Elsevier]

Abstract: Mechanisms of the compositional dependence of blue emission from Nd3+/Tm3+ co-doped Ge–Ga–S–CsBr chalcohalide glasses were investigated. The blue upconversion emissions (centered at 475nm) due to the Tm3+: 1G4 → 3H6 transition decreased as the CsBr/Ga ratio in glasses while the other upconversion emissions from the Nd3+ ions increased. Changes in the local environment of rare-earth ions incurred by the CsBr addition significantly increased the excited state absorption within Nd3+ ions. This resulted in the decrease in the Nd3+ →Tm3+ energy transfer rates that led to the large decrease in blue upconversion emission. [Copyright &y& Elsevier]

In this work, plasma display panel (PDP) glass bodies were prepared by pressureless sintering (PLS) and hot isostatic pressing (HIP). The effects of consolidation conditions including sintering temperature, sintering atmosphere, and HIP variables on final properties were investigated. The glass compacts were sintered at 625–800 °C, holding for 0–5 h, in different atmospheres. To increase the properties, post-sintering HIP was carried out at 650 °C with a pressure of 82 MPa. The microstructures and optical properties were investigated by a scanning electron microscope (SEM) and a spectrophotometer. The experiment results showed that the sintering conditions such as temperature and atmosphere have a large influence on the glass bodies. The relative density of the sintered glass body reached a maximum of 92%; however, after HIP the density reached 99%, almost to full density. The transmittance of HIP material reached 26% at a wavelength of 800 nm, a relatively low value compared with fused glass bodies. The main reasons were scattering from pores and impurities traced to the raw powder, as verified by X-ray photoelectron spectroscopy (XPS). [ABSTRACT FROM AUTHOR]

PbSe quantum dots (QDs) were precipitated in borosilicate glasses, and effects of B 2 O 3 content on the optical properties of glasses were investigated. The diameters of the PbSe QDs in glasses increased from 3.70 nm to 7.32 nm as [B 2 O 3 ] increased from 10 mol% to 20 mol% even when all glasses were heat-treated at 460 °C for 10 h. Photoluminescence (PL) peaks extended to wavelengths of 2154 nm when B 2 O 3 content increased to 20 mol%. The viscosities η of glasses at 460 °C decreased significantly with the addition of B 2 O 3 i.e., 2.86 × 10 13 Pa·s at [B 2 O 3 ] = 0.0% to 1.94 × 10 11 Pa·s at [B 2 O 3 ] = 20%. These decreases in η led to a large increase in the diffusion of ions in glass matrix including Pb 2 + and Se 2 − that facilitated the precipitation and growth of PbSe QDs in glasses. These results demonstrate that the wavelength of PL emissions by QDs can be controlled by manipulating the composition of the host glass. [ABSTRACT FROM AUTHOR]

Lead selenide (PbSe) quantum dots (QDs) doped with Sr 2 + were precipitated in silicate glasses. The absorption and photoluminescence (PL) bands of the glasses blue-shifted as SrO concentration increased. These changes resulted mainly because Sr incorporation increased the band gap of PbSe nanocrystals. After heat treatment at 520 °C for 10 h, mean QD diameters were similar before and after the addition of SrO: ~ 7.2 nm with 0% SrO and ~ 6.9 nm with 10 mol% SrO. However, these two glasses show the absorption bands at 1743 nm and 1246 nm, and PL bands at 1803 and 1370 nm, respectively. These large shifts are due to the increase in the band gap through the formation of Pb 1 − x Sr x Se mixed-type QDs. One typical chemical composition of QDs formed in a glass with 10 mol% SrO after heat treatment at 520 °C for 10 h is Pb 0.89 Sr 0.11 Se with a band gap of ~ 0.58 eV. [ABSTRACT FROM AUTHOR]

Infrared emission properties of oxyfluoride glasses with nominal compositions of 55SiO 2 –10Al 2 O 3 –(35 − x − y)PbF 2 –xErF 3 –yYF 3 (in mol%) with x = 0.1, 0.2, 0.3, or 0.5 and y = 0, or 1.0, were investigated. YF 3 was doped into the glasses to overcome the concentration quenching and achieve efficient infrared emission from Er 3 + doped oxyfluoride glass-ceramics. It was found that introduction of YF 3 can efficiently promote the formation of Er 3 + -doped fluoride nanocrystals even when the doping concentration of ErF 3 was low. With the doping of YF 3 , infrared emission was significantly enhanced and strong infrared emissions at 980 nm and 2730 nm bands were observed. Prolongation of lifetimes of Er 3 + : 4 I 13/2 and 4 I 11/2 energy levels showed that concentration quenching of the infrared emissions was greatly suppressed. These results indicate that oxyfluoride glass-ceramics co-doped with Y 3 + have potentials for efficient infrared applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Blue, green and red emissions were observed from Ho3+ singly doped chalcohalide glasses. [•] White light from Ho3+ singly doped chalcohalide glasses were generated. [•] Color coordinates of white light generated were independent on excitation power. [Copyright &y& Elsevier]

Formation of PbS QDs in the glasses containing a small amount of lead oxide was examined. Oversaturation of sulfur only was sufficient to promote the formation of PbS QDs in the glasses. Upon thermal treatment, absorption of PbS QDs was tuned from 824nm to 2213nm. Infrared photoluminescence, especially, mid-infrared photoluminescence from PbS QDs was observed in the range of 1008nm to 2182nm. Ostwald ripening of PbS QDs occurred when the heat-treatment temperature was 530°C or 540°C, and led to the decrease in the absorption coefficients and splitting of the photoluminescence bands. [ABSTRACT FROM AUTHOR]

Abstract: We experimentally verified, within silicate glasses, the formation of Se2 − color centers that are responsible for a broad visible emission under optical excitation at UV wavelengths. In addition to Raman spectra, all the spectroscopic analyses on absorption, photoluminescence, and photoluminescence excitation unanimously confirm the formation of Se2 − color centers. However, the visible absorption due to Se2 − color centers disppeared upon increasing concentration of Na2O, which implies that their formation would depend on the compositions of silicate glasses. The role of Na2O in the formation mechanism in relation to glass structure is then discussed in terms of various analyses on X-ray diffraction patterns, X-ray photoelectron spectroscopy, and Raman spectroscopy. [Copyright &y& Elsevier]

Highlights: [•] 99Tc (surrogated by Re) was immobilized in an iron phosphate glass. [•] ∼1.1mass% Re was retained, possibly dissolved, in the iron phosphate glass. [•] The 7-day PCT normalized release of Re was <10−2 g/m2. [•] Re concentration in the glass rapidly decreased with increasing melting temperature and duration. [Copyright &y& Elsevier]

Abstract: Glass-forming region of Bi2O3–GeO2–TiO2 (BGT) pseudo-ternary system was determined by using melt-quench method. A series of high transparent glass samples were selected and their structural characteristics were investigated by FT-IR and Raman spectra. By employing Z-scan and optical Kerr shutter techniques with femtosecond laser pulses as excitation source, third-order optical nonlinearities (TON) of the BGT glasses as well as the TON response time were investigated at wavelength of 800 nm. The ultrafast nonlinear response and high figure of merit suggest great potentials of BGT glasses in applications of all-optical switching or related optical devices. [Copyright &y& Elsevier]

Abstract: Absorption and emission spectra for the 3H4↔(3F2, 3H6) transition of Pr3+ ions embedded in Ge–Sb–Se glasses turned out to change systematically upon the introduction of a small amout of Ga. Clear blueshift of the absorption peak wavelengths together with the decrease of absorption cross-section was evident in these glasses containing Ga. We believe that the Ga addition into the conventional covalent selenide glasses makes chemical bonds between rare earth atoms and Se atoms more ionic due to preferential location of the GaSe4 tetrahedra at the second coordination shell of a rare earth atom. Taking into consideration the hypersensitive nature of the Pr3+: 3H4↔3F2 transition, the observed blueshift may manifest the enhanced ionicity of the chemical bonds between Pr and Se in the current Ga-containing glasses. [Copyright &y& Elsevier]

Abstract: A systematic series of (100 − x)(GeTe4.3) − xCdI2/ZnI2 far infrared transmitting glasses were prepared by traditional melt-quenching method. ZnI2 (20mol%) can be introduced in the glassy matrix, while only 10mol% CdI2 can be incorporated in the Ge-Te-CdI2 glass system. Based on differential thermal analysis (DTA) data, most of the glass samples have good thermal stability. A maximum ΔT value of 115°C was obtained for the glass composition 90(GeTe4.3)–10ZnI2. The allowed indirect transition optical band gap was calculated according to the classical Tauc equation. It is found that the indirect optical band gap decreased from 0.619 to 0.569eV with the CdI2 addition and increased from 0.628 to 0.677eV with the ZnI2 addition. According to infrared transmission spectra, the Ge-Te-CdI2/ZnI2 glasses show wide IR transparency. [Copyright &y& Elsevier]

Abstract: Tellurite glasses from TeO2–Bi2O3–BaO pseudo-ternary system were prepared using a conventional melt-quenching method and its glass-forming region was determined. A series of glasses were selected and their third-order optical nonlinearities (TONL) were measured by employing the Z-scan method at a wavelength of 800nm with femtosecond laser pulses. The results showed that glass former Te4+ ions exhibited positive influences on the TONL and glass modifiers Ba2+ ions behaved similarly; low concentrated Bi3+ ions as glass modifiers weakened the nonlinearities, but an excess amount of Bi3+ behaved oppositely. FTIR measurements demonstrated that chemical bonds especially Te–Oeq vibrated at a high energy level remarkably promoted the TONL susceptibility χ (3), and the glass sample with the highest Bi2O3 content exhibited the largest χ (3) value which was due to the presence of BiO3 polyhedra. [Copyright &y& Elsevier]

Abstract: A series of Ge–Te–CuI far infrared transmitting chalcohalide glasses were prepared by traditional melt-quenching method and the glass-forming region was determined. Properties measurements include density, DTA, XRD, SEM, Vis–NIR and infrared (IR) transmission spectra. The results show that with the addition of CuI, the glass-forming ability is improved and nearly 30mol% CuI can be dissolved into the Ge20Te80− x (CuI) x glass system. The density and glass transition temperature of Ge–Te–CuI chalcohalide glasses are within the range 5.459–5.960gcm−3 and 150–184°C, respectively. These glasses all have wide optical transmission window from 1.8 to 25μm and offer an alternative solution for far infrared transmitting materials. [Copyright &y& Elsevier]

Abstract: Efficiency enhancement of a multicrystalline silicon solar cell using down-conversion of Tm3+ and Yb3+ doped silicate glasses was investigated. Na2O–CaO–SiO2 glasses doped with Tm3+ or Tm3+ and Yb3+ were prepared. Distributed Bragg Reflector (DBR) coatings were sputtered on the glass surface to control the transmission and reflection of the desired portion of the solar spectrum. These were placed on a multicrystalline silicon solar cell in combination with a solar spectrum simulator. The efficiency of solar cell with Tm3+ or Tm3+ and Yb3+ doped glasses increased compared to as-prepared glass without rare-earth addition. The efficiency of solar cell with rare earth doped glasses was re-measured three times with same samples, and the real efficiency enhancement can be proved. The potentials, limitations and future perspectives of rare-earth doped glasses with DBR structure on the efficiencies of PV modules were discussed. [Copyright &y& Elsevier]

Abstract: The size and spatial distribution of PbS QDs in glasses need to be controlled in order to achieve desired optical characteristics. This paper reports on the use of several rare-earth oxides such as Ho2O3, Er2O3, and La2O3 to control the size of PbS QDs in silicate glasses. Additions of rare-earth oxides result in blue shifts of the absorption bands from 1344nm to 930nm, and the wavelengths of PL bands can be controlled between 1421nm and 1035nm. Additions of up to 0.8mol% of Ho2O3 decreased the diameters of PbS QDs from 4.82nm to 3.02nm. The same tendencies were found for both Er2O3 and La2O3 additions, although the size of PbS QDs increased as the ionic radius of rare-earth ions increased. It is proposed that clusters of RE–O bonds act as nucleating agents for the precipitation of PbS QDs. [Copyright &y& Elsevier]

Abstract: Heat-treatment was used to precipitate PbS quantum dots (QDs) in silicate glasses doped with different amounts of Ag2O, and the influence of Ag2O on QDs was investigated. Under given heat-treatment conditions, the absorption coefficients and photoluminescence intensities of PbS QDs increased with the addition of Ag2O. Ag clusters formed by thermal treatment nucleated formation of PbS QDs in glasses. [Copyright &y& Elsevier]