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New Yb3+-doped phosphate glasses with a composition of (98.75-x) (90 NaPO3 – 10 Na2O) – x (Al2O3, TiO2, or ZnO) – 1.25 Yb2O3 (in mol-%), with x from 0 to 3, were prepared via conventional melting and quenching process. The thermal and physical properties were studied by differential thermal analysis (DTA) and density measurement, respectively. The glass structure was investigated using visible/infrared spectroscopy and the crystallization properties of the glasses using XRD. Changes in the glass composition were found to have an impact on the glass structure and more importantly on the crystallization process; the addition of Al2O3, TiO2 and ZnO promotes the precipitation of the Na5P3O10 crystalline phase at the expense of NaYb(P2O7) and NaPO3 phases and more importantly, promotes surface crystallization at the expense of bulk crystallization. publishedVersion

Er3+ doped phosphate glasses with the composition 75NaPO3-25CaF2 (mol%) were prepared at different melting temperatures to demonstrate the importance to quantify the fluorine content when preparing oxyfluoride glasses. Indeed, increasing the melting temperature from 900 to 1000 °C leads to a small reduction in the fluorine content from 9.4 at % to 8.8 at % as quantified using EPMA. Whereas this loss of fluorine can be suspected from small changes in the thermal properties of the glass, it increases significantly the glass crystallization tendency in this glass system. This means that a heat treatment of the as-prepared glass should be performed when evaporation of fluorine during the glass melting is suspected. Sample preparation for the characterization of the spectroscopic properties of the glasses is discussed here as well; bulk glasses should be used when measuring the spectroscopic properties of oxyfluoride glasses, which are known to be hygroscopic. It is shown, in this work, that a heat treatment of the glass within the investigated glass system leads to transparent glass-ceramics with volume precipitation of Er3+ doped CaF2 crystals with strong upconversion.

Strong persistent luminescence (PeL) from silica bodies was obtained, for the first time, by sintering silica powder mixed with PeL SrAl2O4:Eu2+,Dy3+ microparticles (MPs). We show that it is not possible to prepare transparent PeL silica glass due to the decomposition of the MPs, which occurs already at 1450 °C. The MPs decomposition was associated with the precipitation of Sr3Al10SiO20 phase when sintering up to 1650 °C and of SrAl2Si2O8 when sintering between 1650 and 1750 °C. Cristobalite was found to also precipitate when sintering for 10 min but has no impact on the PeL of the bodies.

Recently, a phosphate glass with composition 20 CaO-20 SrO-10 Na2O-50 P2O5 (mol%) was found to have good potential as a biomaterial and to possess thermal properties suitable for fiber drawing. This study opened the path towards the development of fully bioresorbable fibers promising for biosensing. In the past, this phosphate glass with CeO2 was found to increase the refractive index and the glass stability. Therefore, a new SrO-containing glass was prepared with 1 mol% of CeO2 and core fibers were drawn from it. A core-clad fiber was also processed, where the core was a Ce-doped glass and the clad undoped, to allow for total internal reflection. The mechanical properties of the core and core-clad fibers are discussed as a function of immersion time in TRIS-buffer solution. Finally, a sensing region was created, in the core-clad fiber, by etching the cladding using phosphoric acid. Then, the change in light transmission, upon immersion in TRIS-buffer solution, was quantified to assess the potential use of the novel core-clad fiber as a biosensor. Upon immersion in TRIS, the core-clad fiber was found to guide light effectively and to maintain a tensile strength of ~150–200 MPa up to 6 weeks in TRIS, clearly showing that this fiber has potential as a biosensing device. acceptedVersion

Phosphate glasses with the composition (90NaPO3-(10-x)Na2O-xNaF) (mol%) with x = 0 and 10 were prepared with blue persistent luminescence (PeL) using direct particles doping method. Commercial CaAl2O4:Eu2+,Nd3+ microparticles (MPs) with blue PeL were added in the glass melt at a lower temperature than the melting temperature. The PeL properties of the glasses were related to the diffusion of Al from the MPs to the glass occurring during the glass preparation, which was found to depend on the temperature at which the MPs are added in the melt and also on the time before casting the melt after adding the MPs. The glass with x = 0 can be prepared with homogeneous PeL if the MPs are added at 575 °C. This Tdoping temperature can be reduced to 550 °C by replacing Na2O by NaF in the glass.

Persistent luminescence (PeL) was obtained, from the first time to the best of our knowledge, from borosilicate bulk glasses. The glasses were prepared using direct doping method. Commercial PeL SrAl 2 O 4 :Eu 2+ ,Dy 3+ microparticles (MPs) were added in the borosilicate glass after melting. The persistent luminescence can be augmented when casting the glass 3 min after adding the MPs at 950 °C. Although the borosilicate glasses exhibit persistent luminescence, the glass melt has a corrosive behavior on the MPs leading to the diffusion of Al and Sr into the glasses.

We report our findings on the impact of the glass composition on the corrosion of microparticles occurring during the preparation of glass-ceramics using the direct doping method. Microparticles (MPs) with the composition Sr4Al14O25:Eu2+,Dy3+ with blue-green persistent luminescence were chosen as the changes in their spectroscopic properties can be related to the MPs’ corrosion. The MPs were added in phosphate-based glasses with different compositions. When using the same doping parameters, the glass system with the composition 90NaPO3-10Na2O (mol%) was found to be the least corrosive on the MPs whereas the glass system with the composition 90NaPO3-10NaF (mol%) is the most corrosive on the MPs probably due to their different viscosity at 575 °C, the temperature at which the MPs are added in the glass melts.

Glasses with the composition (75 NaPO3-(25-x) CaO-xCaF2) (in mol %) were prepared with 0.15 mol% of Er2O3. The effect of the glass composition and of heat treatment on the spectroscopic properties of the newly developed glasses is reported. With the progressive replacement of CaO by CaF2, the Er3+:4I13/2 lifetime and the intensity of the upconversion emission increase whereas the intensity of the emission at 1.5 μm decreases due to the decrease in the phonon energy in the as-prepared glasses. The glasses were heat treated at 20 °C above their respective glass transition temperature for 17 h to form nuclei and then at their crystallization temperature from 15min to 1 h to grow the nuclei into crystals. The heat treatment leads to the precipitation of crystalline phases, the composition of which depends upon the glass composition. As the Er3+:4I13/2 lifetime increases and the intensity of the upconversion increases for the glass with x = 0 after heat treatment, the Er3+ ions are expected to be incorporated into the phosphate-based crystals. However, as the shape of the emission band at 1.5 μm remains unchanged and the intensity of the upconversion decreases significantly after heat treatment of the glasses with x > 10, the crystals found in the glass-ceramics with x > 10 are thought to free of Er3+ ions. Although Er3+ ions entered in the CaF2 crystals precipitating in aluminosilicate glass, the Er3+ ions are believed to remain in the amorphous phosphate part of the glass-ceramic containing CaF2 crystals.

Findings on the decomposition of persistent luminescent (PeL) SrAl2O4:Eu2+,Dy3+ microparticles (MPs) in phosphate glass melt under static condition are reported. PeL phosphate glasses with the composition (50P2O5-10Na2O-40SrO) (in mol%) were prepared by adding the MPs in the glass melt. The decomposition of the MPs occurs during the preparation of the glass and leads to changes in the Eu2+ sites and to the formation of Eu3+ which decreases the PeL properties of the glasses. The decomposition of the MPs depends on the temperature at which the MPs are added in the melt and also on the time before casting the melts.

New oxyfluorophosphate glass-based composites which exhibit not only green upconversion under 980 nm pumping but also green persistent luminescence (PeL) after being UV charged were successfully prepared using the direct doping method. The composites are composed of a glass-ceramic with Er3+ doped CaF2 crystals and of the persistent luminescent particles with the SrAl2O4:Eu,Dy composition. In the standard direct doping method, the glass melt is quenched few minutes after adding the PeL particles in the melt held at a temperature lower than the melting temperature. It is demonstrated that the direct doping method should be modified when preparing oxyfluoride glasses with PeL particles to limit not only the decomposition of the PeL particles in the glass but also the fluorine evaporation occurring during the glass preparation. Here, the composites were prepared by quenching the melt right after adding the PeL particles. The modified direct doping method allows the preparation of glass-based composites with strong green upconversion and homogeneous green persistent luminescence. publishedVersion

Effect of CaF 2 addition at the expense of CaO on the thermal, physical, optical and structural properties of glasses in the NaPO 3 –CaO system was studied. The glasses were prepared by the conventional melt quenching method. For each glass, the thermal properties were studied by differential thermal analysis (DTA) and the optical properties by UV–Vis-NIR spectroscopy. The changes in the glass structure induced by the progressive replacement of CaO by CaF 2 were investigated using IR and Raman spectroscopies. The glasses were heat treated at 20 °C above their respective glass transition temperature for 17 h to form nuclei and then at their peak crystallization temperature for 1 h to grow the nuclei into crystals. An increase in the CaF 2 content increased the polymerization of the phosphate network leading to shift of the band gap to lower wavelength and reduced the crystallization tendency of the glasses. At least two crystalline phases precipitated in all the investigated glasses, the composition of which depended on the CaF 2 content. Finally, bulk crystallization was suspected to occur in the oxyfluorophosphate glasses.

The melt-quenching method is employed to prepare the amorphous phosphate glasses containing silver nanoparticles (Ag NPs). The structural characteristics of phosphate glasses were investigated by X-ray diffraction, thermal analysis, transmission electron microscopy, UV–Vis spectroscopy, Raman, and infrared spectroscopy. The transmission electron microscopic images confirm the presence of spherical silver NPs having an average diameter in the range of 20–40 nm. The EDX analysis spectrum shows the presence of Ag element. Important structural changes induced by the Ag2CO3 addition to the phosphate glass, Raman- and IR-spectroscopic studies were carried out in order to correlate the variations in the glass properties with variations of the glass structure. The surface plasmon resonance (SPR) peak of silver nanoparticles embedded in Er3 + doped phosphate glass is evidenced at ~ 403 nm. From the absorption spectra, the optical band gap is found to decrease with the increase of Ag NPs' concentration. All the obtained results in the present study were reported and discussed in detail.

In this paper, phosphate based glasses with persistent luminescence properties were processed using standard melting process in air by adding SrAl 2 O 4 :Eu 2+ ,Dy 3+ or CaAl 2 O 4 :Eu 2+ ,Nd 3+ in the glass batch before melting. All produced glasses were characterized using SEM/EDXA, Raman spectroscopy and photoluminescence. We discuss the effect of melting conditions (temperature and duration of the melting) on the persistent luminescence properties of the microparticles containing glasses. It is demonstrated that the melting in air allows for the preparation of glasses with persistent luminescence if the melting conditions are carefully controlled.

International audience; We report results on the processing and characterization of different glass preforms and single core fibers within the SiO2-Na2O-B2O3-Er2O3-P2O5-Al2O3 system. Micro-Raman spectroscopy was used to identify post-draw structural modification. The differences in the micro-Raman spectra recorded on the preform and on the fiber glass were attributed to a change in the structure induced by the drawing process. Changes in the silicate network organization and small scale molecular orientation within the glass matrix are suspected to occur during the fiber drawing process. We found that the extent in the changes between the preform and fiber properties depend on the glass composition. The glass network of the Al-containing fiber is expected to be less sensitive to the drawing process than that of the fiber matrix as the network of this Al-containing fiber is formed by a larger number of Si-BO units in the network and neutral three-coordinated boron compared to the network of the fiber matrix. From the micro-Raman spectra, formation of small crystals is suspected to occur in the P-containing glasses during the fiber drawing process. The resulting fibers were found to have propagation losses at 1330 nm and Er3+ absorption between (7 ± 1) and (25 ± 1) dB/m and (36 ± 1) and (47 ± 1) dB/m, respectively, depending on the glass composition.

This paper investigates the effect of fiber drawing on the thermal and structural properties as well as on the glass reactivity of a phosphate glass in tris(hydroxymethyl)aminomethane-buffered (TRIS) solution and simulated body fluid (SBF). The changes induced in the thermal properties suggest that the fiber drawing process leads to a weakening and probable re-orientation of the POP bonds. Whereas the fiber drawing did not significantly impact the release of P and Ca, an increase in the release of Na into the solution was noticed. This was probably due to small structural reorientations occurring during the fiber drawing process and to a slight diffusion of Na to the fiber surface. Both the powders from the bulk and the glass fibers formed a Ca-P surface layer when immersed in SBF and TRIS. The layer thickness was higher in the calcium and phosphate supersaturated SBF than in TRIS. This paper for the first time presents the in vitro reactivity and optical response of a phosphate-based bioactive glass (PBG) fiber when immersed in SBF. The light intensity remained constant for the first 48h after which a decrease with three distinct slopes was observed: the first decrease between 48 and 200h of immersion could be correlated to the formation of the Ca-P layer at the fiber surface. After this a faster decrease in light transmission was observed from 200 to ~425h in SBF. SEM analysis suggested that after 200h, the surface of the fiber was fully covered by a thin Ca-P layer which is likely to scatter light. For immersion times longer than ~425h, the thickness of the Ca-P layer increased and thus acted as a barrier to the dissolution process limiting further reduction in light transmission. The tracking of light transmission through the PBG fiber allowed monitoring of the fiber dissolution in vitro. These results are essential in developing new bioactive fiber sensors that can be used to monitor bioresponse in situ.

The impact of Al2O3 and Y2O3 addition on the structure, Yb3+ luminescence and crystallization is investigated for glasses in the P2O5-SrO-Na2O system. Although the addition of Al2O3 and Y2O3 leads to a more connected phosphate network as evidenced using IR and Raman spectroscopies and increases the glass transition temperature, it does not affect strongly the site of the Yb3+. The addition of Al2O3 and Y2O3 slightly decreases the rate of the glass crystallization. Surface crystallization occurs upon heat treatment. Crystallization was confirmed by the presence of sharp peaks in the XRD patterns of the glasses. Independently of the glass composition, different crystalline phases precipitate in the glasses upon heat treatment. The precipitation of the Na1O7P2Yb1 crystal phase leads to an increase of the excited state 2F5/2 lifetime of Yb3+ and also of the bandwidth of the Yb3+ emission band centered at 1 μm. Keywords: Yb3+ doped phosphate glasses, Heat treatment, Nucleation and growth, Raman & Infrared spectroscopies, Yb3+ luminescence properties

The kinetics of crystallization of glasses in the (90 − x)TeO 2 –10Bi 2 O 3 –xZnO system with x = 15, 17.5, 20 and 25 have been studied using differential thermal analysis (DTA), hot stage XRD and optical microscopy. Thermal properties, activation energy for crystallization, Johnson–Mehl–Avrami exponent, nucleation and growth regimes and rates were determined and shown to depend on glass composition. These variations were related to the domain of glass formation in the TeO 2 –Bi 2 O 3 –ZnO ternary glass system: the glasses with x = 15 and 25 are at the limit of the glass formation domain while the glasses with x = 17.5 and 20 are in the middle of the glass-forming region. From the Johnson–Mehl–Avrami parameter, which increases slightly from 1.7 to 2.2 when x increases from 15 to 25, and from optical micrographs, the predominant crystallization in the investigated glasses is expected to be 2 dimensional bulk crystallization governed by diffusion. Using XRD, we found that Bi 2 O 3 crystals are the first crystals to form in the glasses when heat treated at their respective temperatures of maximum nucleation. When heat treated at a higher temperature the Bi 2 O 3 crystals were found to transform into Bi 2 Te 4 O 11 . We observed an increase in the crystal size when the glasses were heat treated at their respective temperatures of maximum nucleation revealing a probable overlap between the nucleation and growth regimes in all the glasses, the largest overlap being for the glass with x = 15. Thus, this glass is not an appropriate material candidate for applications which require controlled nucleation and growth as a large distribution of crystal sizes can be obtained in the glass when heat treated at its temperature of maximum nucleation rate. The glass with x = 25 is suspected to be also an inappropriate candidate for this kind of applications as it has a higher tendency to fully crystallize in a small temperature range than the other glasses as evidenced by its high N q and I n .

The viscosity behavior of glasses with the composition (90-x)TeO2–10Bi2O3–xZnO with x = 15, 17.5, and 20 (TBZ glasses) and 80TeO2–(20-y)Na2O–yZnO system with y = 0, 5, and 10 (TNZ glasses) have been measured as a function of temperature using a beam-bending (BBV) and a parallel-plate (PPV) viscometer. The structure of the glass’ network has been characterized using Raman spectroscopy and has been related to the viscosity temperature behavior and the fragility parameter (m) of the glasses. As the concentration of ZnO in the TBZ system (x) increases, the fragility parameter of the glass increases, whereas it decreases with an increase of the ZnO concentration (y) in the TNZ system. In both glasses, these variations in m have been related to the partial depolymerization of the tellurite network associated with the level of modifier content. The depolymerization of the tellurite network is believed to be the result of a reduction in the number of [TeO4] units and the formation of [TeO3] and [TeO3+1] units that occurs with a change in TeO2 content in the TBZ system and modifier content in the TNZ system.

New oxy-sulfo-telluride glasses have been prepared in the Ge–Sb–Te–S–O system employing a two-step melting process which involves the processing of a chalcogenide glass (ChG) and subsequent melting with TeO 2 or Sb 2 O 3 . The progressive incorporation of O at the expense of S was found to increase the density and the glass transition temperature and to decrease the molar volume of the investigated oxy-sulfo-telluride glasses. We also observed a shift of the vis–NIR cut-off wavelength to longer wavelength probably due to changes in Sb coordination within the glass matrix and overall matrix polarizability. Using Raman spectroscopy, correlations have been shown between the formation of Ge- and Sb-based oxysulfide structural units and the S/O ratio. Lastly, two glasses with similar composition (Ge 20 Sb 6 S 64 Te 3 O 7 ) processed by melting the Ge 23 Sb 7 S 70 glass with TeO 2 or the Ge 23 Sb 2 S 72 Te 4 glass with Sb 2 O 3 were found to have slightly different physical, thermal, optical and structural properties. These changes are thought to result mainly from the higher moisture content and sensitivity of the TeO 2 starting materials as compared to that of the Sb 2 O 3 .

We report results on the processing and characterization of tellurite-based glass preforms (core and cladding bulk glasses) and fibers within the TeO2–Bi2O3–ZnO glass system. The core–clad fiber has been drawn from a core–clad preform prepared via rotational casting. Using Cu as a tracer to assess interface quality between the core and clad layers, we show excellent cladding layer thickness uniformity across lengths of up to 40 mm in a 65 mm long perform. No measurable diffusion of Cu between the core and the clad has been observed, within the accuracy of measurement, indicating good stability and interface quality during casting of melted glass. Micro-Raman spectroscopy has been used to identify subtle post-draw structural modification induced in the preform following the fiber drawing. These changes have been attributed to modification to the bulk glass’ thermal history upon drawing and small scale molecular orientation of chain units within the tellurite glass matrix produced during the fiber drawing process. The resulting fiber was found to have an index step of (0.009 ± 0.002) between the fiber core and clad composition at 632 nm and propagation losses of (3.2 ± 0.1) dB/m at 632 nm and (2.1 ± 0.1) dB/m at 1.5 μm. The primary source of loss in the near-IR (NIR) is associated with residual hydroxyl (OH−) groups in the bulk preform which remain in the glass fiber.

Thin film Ge23Sb7S70 chalcogenide glass has emerged as an important material system for photonic applications due to its high non-linear refractive index. However, one of the challenges is developing low-cost methods to deposit films of glassy material while retaining glass stoichiometry and high film quality. In this paper, we demonstrate a spin-coating technique for the deposition of such films. The dissolution mechanisms of Ge23Sb7S70 in different solvents are studied in order to select the optimal solvent for film deposition. We show that the use of amine-based solvents allow the deposition of stoichiometric films in contrast to alkaline solutions. Films with low surface roughness (RMS roughness

New passive and active oxysulfide glasses have been prepared in the Ge–Ga–Sb–S–O system employing a two-step melting process which involves the processing of the chalcogenide glass (ChG) and its subsequent melting with amorphous GeO 2 or Sb 2 O 3 powder. Optical characterization of the oxysulfide glasses has shown that the UV cut-off wavelength decreases with increasing oxygen content. Using Raman spectroscopy, correlations have been made between the formation of new Ge- and Sb-based oxysulfide structural units, the Sb content and the O/S ratio. We demonstrate the successful processing of active rare earth doped oxysulfide glasses by melting the chalcogenide glass with Er 2 O 3 and Sb 2 O 3 and also by melting the Er 3+ doped chalcogenide glass with Sb 2 O 3 . Modification of the emission spectra at 1500 nm of Er 3+ doped samples with the introduction of oxygen revealed that Er 3+ most likely exists in dual O- and S-neighbor environments. Finally, the photo-response of these new glasses upon near-IR femtosecond laser irradiation has been investigated as a function of Sb content and O/S ratio and shows that the glasses are photo-sensitive to NIR fs laser light with the magnitude of the photo-sensitivity dependent on the glass’ Sb content and O/S ratio.

The viscosity behavior of (1 − x )NaPO 3 − x Na 2 B 4 O 7 glasses ( x = 0.05–0.20) have been measured as a function of temperature using beam-bending and parallel-plate viscometry. The viscosity was found to shift to higher temperatures with increasing sodium borate content. The kinetic fragility parameter, m , estimated from the viscosity curve, decreases from 52 to 33 when x increases from 0.05 to 0.20 indicating that the glass network transforms from fragile to strong with the addition of Na 2 B 4 O 7 . The decrease in fragility with increasing x is due to the progressive depolymerization of the phosphate network by the preferred four-coordinated boron atoms present in the low alkali borate glasses. As confirmed by Raman spectroscopy increasing alkali borate leads to enhanced B–O–P linkages realized with the accompanying transition from solely four-coordinated boron (in BO 4 units) to mixed BO 4 /BO 3 structures. The glass viscosity characteristics of the investigated glasses were compared to those of P-SF67 and N-FK5 commercial glasses from SCHOTT. We showed that the dependence of the viscosity of P-SF67 was similar to the investigated glasses due to similar phosphate network organization confirmed by Raman spectroscopy, whereas N-FK5 exhibited a very different viscosity curve and fragility parameter due to its highly coordinated silicate network.

In this paper, we report results of a systematic study to evaluate the relationship between compositional variation and the photo-response of Gallium containing sulfo-selenide glasses upon IR femtosecond laser exposure. We show that IR femtosecond laser irradiation in this system results in near-surface photo-expansion, which based on micro-Raman spectroscopy, has been related to an increased connection of GeS 4 units to form corner sharing GeS 4/2 units with a concurrent formation of S–S bridges. The lower surface photo-expansion of the Ga- containing sulfide and sulfo-selenide glasses compared to that of the Ga-free sulfide and sulfo-selenide glasses has been related to the presence of GaS 4 and Se–Se isolated units in the germanate glass network which are expected to restrict the connection between GeS 4 units during laser exposure. Such mechanistic understanding of material modification opens the pathway towards the laser writing of active photonic devices in the near-surface of these glasses.

Se-rich optical fibers have been drawn from As–Se-based preforms and their corresponding thermal properties have been analyzed. Micro-Raman spectroscopy has been used to characterize and compare the structure of the preform and the resulting fiber. The spectra show that the fibers possessing the same thermal properties as their corresponding preforms, exhibit similar structure while no evidence of crystallization, as assessed via X-ray diffraction analysis, could be detected.

We report in this paper, results on the formation and dissolution of Cu-based nanoparticles in sol–gel SiO 2 thin films using heat treatment and UV light exposure, respectively. Using UV–vis-NIR spectroscopy, we have shown that Cu 2 O nanoparticles can be generated by controlling the aging of the sol prior to film deposition while the Cu 0 nanoparticles can be synthesized using a heat treatment in H 2 atmosphere at 550 °C for 6 h. It has been also demonstrated that irradiation with an UV pulsed (Q-switched Nd:YAG) or continuous black ray UV lamp can dissolve these Cu-based nanoparticles with controlled, spatial selectivity. The mechanism of the dissolution process was found to be mainly thermal. Finally, we report a new analytical technique for detecting/confirming the presence of low densities of Cu nanoparticles in the films, based on a relative heat flow measurement of such films using a micro-thermal analyzer (e.g., TA Instruments μTA model 2990).

Waveguides from thermally evaporated Ge 23 Sb 7 S 70 films have been fabricated using both plasma etching and lift-off techniques. The two methods have been compared in their ability to provide high quality, low-loss waveguides for microphotonics applications. We have demonstrated in this paper that low-loss 3 μm and 4 μm wide channel waveguides can be fabricated using CHF 3 and SF 6 plasma etching, and lift-off, respectively. Additionally, lift-off does not change the structure of the waveguide during the fabrication whereas the structure of the plasma etched waveguide differs slightly from that of the films. Finally, channel waveguides fabricated using lift-off leads to a low RMS roughness of 10 ± 2 nm, compared to those fabricated by a plasma etching process which lead to a higher RMS roughness of 17–20 nm. As-fabricated waveguides have been found to exhibit optical propagation losses of 3–5 dB/cm at 1550 nm. These high losses are attributed to scattering by sidewall roughness and defects arising from the fabrication process.

Silica nanoparticles, prepared by the Stober method, have been doped with Eu 3+ , Dy 3+ , or processed to result in Au nanoparticles on the silica surface. The luminescence of the rare earth (RE)-doped SiO 2 particles has been studied as a function of the nature of the RE, their concentration and also of the presence of Au nanoparticles at the surface of the SiO 2 nanoparticles. We have shown that the Eu 3+ emission is observable over the experimental conditions examined, whereas it was not possible to observe any emission for Dy 3+ doped materials. No enhancement of the Eu 3+ emission was observed following the adsorption of gold nanoparticles at the surface of the SiO 2 nanoparticle, however an excitation at 250 nm leads to both the emission of the matrix and Eu 3+ showing an energy transfer from the SiO 2 matrix to Eu 3+ ions.

Germanium-based sulfide glasses in the Ge–Sb–S system have been elaborated and studied. A relationship between the structure, the composition and the linear optical properties of the glass has been established. The effects of the introduction of Sb on the structure using IR and Raman spectroscopies and on the linear refractive index have been discussed. We have shown that the progressive introduction of Sb 2 S 3 in the glass system (1 − x )GeS 2 – x Sb 2 S 3 (with x = 0.10, 0.20, 0.40, 0.62 and 0.80) decreases the number of GeS 4 units in the glass network. As results, the glass transition temperature, the Vicker's microhardness and the stability of the glass against crystallization decrease dramatically. An increase in the density and the linear refractive index as well as shift of the absorption bandgap to infrared have also been observed. Similar behavior has been observed for the glasses of composition Ge 0.23 Sb y S 0.77− y with an increase of y , except in the material's Vicker's microhardness, which increases with an increasing Sb content. This latter result indicates that the microhardness also depends on Sb 2 S 3 content but seems to be more sensitive to GeS 2 content variation.