Enhanced 1.5 μm emission from Yb3+/Er3+ codoped tungsten tellurite glasses for broadband near-infrared optical fiber amplifiers and tunable fiber lasers

Strong 1.5 μm emission with full width at half maximum of 64 nm is achieved in 3 mol% Yb2O3 and 1 mol% Er2O3 codoped tungsten tellurite glass. The present glass shows large gain bandwidth (6.78 × 10−26 cm3) and figure of merit (4.06 × 10−23 cm2 s).

Catoptric Theatres

Alluding to the Theatrum Catoptricum described by Athanasius Kircher in Ars Magna Lucis at Umbrae (1646), this article aims to present glass and mirrors, not as mere objects or materials, but as perceptual and spatial devices, defining a technology of immersion. Imbued with a dazzling energy, mirrors and glass appear to defy both spatial logic and the logic of the eye, triggering new ways of observing, channelling and manipulating light, thus redefining the role played by the immaterial in the production and experience of space. With their framing, amplifying, multiplying or distorting qualities, mirrors and glass also entail a shift of emphasis away from materiality as a merely tectonic or expressive medium, towards matter as an activator and catalyst of effects and experiences. Unravelling the magical force and transformative quality of glass and mirrors requires an inquisitive journey, spanning different disciplines as well as historical, socio-cultural and technological contexts. Reflecting the myriad effects and affects of mirrors and glass, a kaleidoscopic range of examples will establish multidirectional dialogues. Although from different eras, the selected works, each one a ‘catoptric theatre,’ will provide the opportunity, not only to reimagine spatial relationships and boundaries, but also to decode the essence of atmospheric staging, suggesting a material pre-history to contemporary concerns for atmosphere and its production. From the enchanting effects of the Baroque Gallery of (fragmented) Mirrors at Villa Palagonia in Bagheria, via Sir John Soane’s unprecedented use of tinted glass and mirrors in his House-Museum in London, to the twentieth century light modulating machines of László Moholy-Nagy, Adolf Luther’s kaleidoscopic assemblages, and twentieth-century architect Ludwig Mies van der Rohe’s belief in the performative nature of glass, the reader will discover multiplicities of meanings and ambiguities of reflections, exploring their atmospheric potentiality.

Er3+/Nd3+ Codoped Lithium Niobate Tellurite Glass: Improvement in Energy Transfer Induced Photoluminescence

The Er3+/Nd3+ doped glasses of the form (69-x)TeO2-15Li2CO3-15Nb2O5-1Er2O3-(x)Nd2O3 with x=0.4, 0.8 and 1.0 mol % are successfully made by using conventional melt-quenching technique. It was found both the photoluminescence intensity and stimulated emission cross-section were found increase with Nd3+ codoping. Efficient blue (497 nm, 2G9/2 → 4I9/2), green (550 nm, 2G7/2 → 4I9/2), orange (618 nm, 2H11/2→4I9/2), and red (635 nm, 4F9/2→4I9/2) spectra were observed. The results suggest that the present glass shows the potential candidate of broadband amplifiers and lasers as it is comparable with other Nd3+ doped other host.

Studies on Raman Spectra of Cu2+ Ion Doped B2O3-K2O-ZnO-BaO Glasses

Glasses with compositions 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO were prepared using melt quenching technique. The effect of BaO content in present glass system doped with copper ion in place of ZnO has been studied with respect to structural properties. Raman spectroscopy is an experimental technique appropriate for providing information about  the structure, local arrangement of the atoms in the present glasses. The Raman spectra of glasses were recorded at room temperature in the range 200-1800 cm-1 using a He-Ne excitation source having wavelength 632.81 nm. The Raman peaks appeared around 760 cm-1 assigned symmetric breathing vibrations of six-membered ring with both BO3 triangle and BO4 tetrahedral. The intensity of these peaks is slightly varied with the addition of BaO content while the broadness is found to be larger at 30 mol% of BaO than 30 mol% ZnO. This indicates that certain BO4 units could be preferentially converted while those in ring groups could be stabilized. Raman studies it is concluded that present glasses are composed of [BO4] and [BO3] units in metaborate, orthoborate, diborate groups.

EPR AND DSC STUDIES ON MgO–R2O–B2O3–V2O5 ALKALI GLASSES

EPR and DSC studies were carried out on MgO – R 2 O – B 2 O 3– V 2 O 5 glasses. The electron paramagnetic resonance spectra of V 4+ ion in the ternary glass system x MgO –(30-x) R 2 O –70 B 2 O 3 ( R = Li, Na, K ) were recorded at X-band frequencies at 303 K. The V 4+ ions in the present glass system exists as VO 2+ ions in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C 4v and the ground state of 3d1 ion is dxy. Tetragonality (Δg‖/Δg⊥) of V 4+ ion sites show a nonlinear variation with MgO content in the glasses. The covalency rates indicate moderate covalency for σ and π-bonds. The optical basicity values were also reported. Glass transition temperatures (Tg) of the glasses were found to increase linearly with increasing MgO content.

Structural and Physical Properties ofFe2O3-B2O3-V2O5Glasses

The structural and physical properties ofxFe2O3-(40-x)B2O3-60V2O5 (0≤x≤20)glass system have been investigated. The samples were prepared by normal melt-quench technique. The structural changes were inferred by means of FTIR by monitoring the infrared (IR) spectra in the spectral range 600–4000cm-1. The absence of boroxol ring (806 cm-1) in the present glass system suggested that these glasses consist of randomly connectedBO3andBO4units. The conversion ofBO3toBO4andVO5toVO4tetrahedra along with the formation of non-bridging oxygen's (NBOs) attached to boron and vanadium takes place in the glasses under investigation. The density and molar volume of the present glass system were found to depend onFe2O3content. DC conductivity of the glass system has been determined in the temperature range 310–500 K. It was found that the general behavior of electrical conductivity was similar for all glass compositions and found to increase with increasing iron content. The parameters such as activation energy, average separation between transition metal ions (TMIs), polaron radius, and so forth have been calculated in adiabatic region and are found consistent with Mott's model of phonon-assisted polaronic hopping.

Crystallization of a SiO2-MgO-Al2O3-K2O-Fe2O3-F Glass

The phase-separation and the crystallization of SiO2-MgO-Al2O3-K2O-Fe2O3-F glass were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electron probe of microanalyzers (EPMA). The results reveal that the varieties and the morphology of crystalline phases formed depend sensitively on the thermal treatment schedules. During the isothermal treatments, the crystalline phases of mica, mica and iron oxide (FeFeO4), and FeFeO4 as major crystals are precipitated in the glass samples heat-treated at 900, 1000 and 1050°C respectively. However, the two-step heat treatment beginning at 900°C for 1h and subsequently followed at 1050°C for 1h leads to the precipitation of mica crystal and no any signs of FeFeO4 crystalline phase is observed. Also the morphology of sample is different from that of the isothermally treated glass at 1050°C, but is similar from that of sample at 900°C. A “worm”-shaped phase-separation is observed in the sample heated at 800°C for 0.5h, which exhibits different morphology from that of droplet- or globule-shape conventionally discerned. EPMA results show that the incorporation of Fe2O3 accelerates accumulation of fluorine element, promoting the phase-separation and the crystallization of the present glass.