首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A series of boron- and germanium-free silicate glasses was developed for the core glass of high-numerical-aperture double-crucible optical fibers. When combined with a boro-silicate cladding glass from a series also investigated in this study, fibers with a numerical aperture in the range 0.3 to 0.5 can be produced. The relatively high refractive indices in the core glasses are achieved by including large mole fractions of BaO, CaO, and ZnO, accompanied in some cases by smaller additions of ZrO2 and/or Y2O3 in the glass composition. Measurements of the refractive index, density, Rayleigh scattering coefficient, and viscosities and observations of the devitrification behavior and chemical durability of the glasses are presented. Attenuation spectra of suitable core glasses and of double-crucible optical fibers comprised of different core and cladding combinations yielding high numerical apertures are given. The fibers have attenuations near 10 dB/km at 850 nm.  相似文献   

2.
Transparent magnetic glass-ceramics were produced by infiltrating nano-porous glass with nitrate salts and firing. The resultant glass-ceramics contained spinel ferrite nanocrystals that exhibited ferromagnetic and superparamagnetic behavior depending on composition and firing temperature. Transparency in the near infrared was obtained when oxidizing conditions were used to prevent Fe2+ formation, while the porous matrix ensured nano-sized crystallites to limit scattering losses. MnFe2O4 glass-ceramics treated at 1000°C offered the best combination of magnetic and optical properties with a saturation magnetization of 5.6 emu/g, a Verdet constant of 16.5°/cm, and losses below 3 dB/mm at 1550 nm.  相似文献   

3.
To obtain low transmission loss optical fibers from ultrapure multicomponent silicate glasses, it is necessary to add small quantities of As2O3 (or Sb2O3). In optical fibers prepared from glasses without these agents, a significant increase in loss is observed. To investigate this effect, the influence of As2O3 (added to the batch and present in the glass as As2O5) on the optical properties of ultrapure silicate glasses was studied. These properties are the Rayleigh scattering loss coefficient, transition metal absorption, and position of the uv absorption edge. This study showed that the increase in loss of As2O3-free glass cannot be assigned to any of these contributions and was attributed to absorption by electrons, trapped in relatively shallow traps in the glass network. The As5+ ions serve as deep traps and therefore remove the additional absorption. The same phenomenon, although much more pronounced, was observed in optical fibers prepared from alkali borosilicate glasses.  相似文献   

4.
The role of cerium in the suppression of gamma-ray induced coloration in glass has been found to depend on the relative concentration of Ce3+ to Ce4+ ions as well as on the total cerium content. In a borate glass having high ultraviolet transmission, it has been found that both Ce3+ and Ce4+ ions are necessary to suppress the optical absorption bands induced in the visible region. The role of cerium can be explained on the basis of a change in its oxidation state as a result of gamma irradiation. It is postulated that the cerous ions, by the reaction Ce3+→ Ce4++ e , suppress the induced visible band at 2.36 ev (525 mμ), which may result from positive hole centers. High cerous ion concentration results, however, in an induced center (Ce3++ e ) which absorbs in the visible at about 1.9 ev (650 mμ). The presence of Ce4+ ions near Ce3+ prevents the formation of this center possibly by the reaction Ce4++ e → Ce3+. These induced opposite changes in the oxidation state of cerium tend to maintain a balance in the ratio of Ce3+ to Ce4+ ions in the glass during irradiation, and the suppression of the visible bands depends on this ratio.  相似文献   

5.
Selenide glass optical fibers were fabricated for Ge30Sb10Se58S2 and Ge20Sb10Se70 glasses. Their transmission loss has been measured and compared with the theoretical attenuation loss that was calculated taking into account the electronic transition absorption, Rayleigh scattering, and multiphonon absorption. A low attenuation loss of the Ge20Sb10Se70 glass composition in 1.2–1.7 μm range has been expected due to its high optical band gap energy compared with the Ge30Sb10Se58S2 glass. However, the measured attenuation loss of the Ge30Sb10Se58S2 glass fiber was ∼13 dB/m at 1.5 μm while Ge20Sb10Se70 glass showed ∼82 dB/m. An enhanced weak absorption tail due to the localized states of the Ge20Sb10Se70 glass was responsible for this behavior. Structural defects are related to the localized states and discussed for the present glass compositions.  相似文献   

6.
The refractive index dispersion and infrared (IR) reflection spectra of soda magnesium silicate glasses with low Rayleigh scattering were measured to evaluate their potential for use in fabricating ultralow-loss fibers. The zero-material dispersion wavelength (λ0) was found to be around 1.5 μm, which is one of the key wavelengths in the present telecommunication system. The compositional dependence of λ0 was found to relate to the population of nonbridging oxygen. Since the oscillation strength and frequency of the Si—O stretching vibrations of the glasses were found to be smaller than those of silica glass, their IR absorption loss was considered to be less than that of silica glass. The minimum loss due to the intrinsic factors, Rayleigh scattering and IR absorption, was estimated to be 0.06 dB/km at 1.6μm.  相似文献   

7.
Transparent glass-ceramics containing ZnAl2O4:Co2+ and LiGa5O8:Co2+ crystallites have been prepared by heat treatment of glasses in the zinc aluminosilicate and lithium gallate silicate systems, respectively. Crystalline LiGa5O8 was already precipitated in an as-prepared specimen, while ZnAl2O4:Co2+ precipitated from the glass upon heat treatment. The crystallite size varies from about 5 to 20 nm with increasing heat treatment temperature for both systems, and glass-ceramics containing crystallites of less than about 10 nm are transparent. The low-temperature optical absorption and emission spectra are compared with those of single crystals, indicating that almost all of the Co2+ ions replace Zn2+ ions in the ZnAl2O4 system, while some of the Co2+ ions are incorporated into the LiGa3O8 system, although the amount of Co2+ which remains in the glass matrix is rather large in the latter system.  相似文献   

8.
Borosilicate glasses, 5B2O3· 95SiO2 (mol%), containing TeO2 and ZnO nominally equivalent to 10 wt% Te and ZnTe were prepared by a solgel method from Si(OC2H5)4, B(OCH3)3, H6TeO6, and Zn(NO3)2. A study by electron spectroscopy for chemical analysis (ESCA) showed that glasses heated at high temperature (450°C) in air contained both Te6+ and Te4+ ions on the surface layer, but that mainly Te4+ ions occurred inside the bulk glass. When solgel-derived borosilicate glasses containing the TeO2 compound were reduced at elevated temperature in a hydrogen atmosphere, Te crystallites ranging in size from 4 to 15 nm were produced at a lower temperature, between 200° and 250°C. The absorption edge moved from the infrared to the visible wavelength region as the particle size decreased to about 4 nm. For glasses containing both TeO2 and ZnO, ZnTe crystallites formed at high temperature—over 300°C—and existed along with the Te phase.  相似文献   

9.
Tellurite Glasses for Broadband Amplifiers and Integrated Optics   总被引:1,自引:0,他引:1  
The present investigation discusses the advantage of using RE-ion-doped (Nd3+, Tm3+, and Er3+) TeO2 glasses for developing fiber and planar broadband amplifiers and lasers. The spectroscopy of RE-ion-doped fibers and glasses is discussed along with the thermal properties of glass hosts. The results of emission from the 3H4 level in single-mode Tm3+-doped tellurite fiber show that the emission band overlaps with Er3+ emission from the 4I13/2 level and Nd3+ emission from the 4F3/2 level in silicate and tellurite glasses, thereby enabling the development of amplifiers and lasers between 1350 and 1650 nm. Recent results using Z-scan measurements of nonlinear refractive index and absorption demonstrate that the third-order nonlinearity in undoped TeO2 glasses is of the order of 2 × 10−15 to 3 × 10−15 cm2·W−1 between 1300 and 1550 nm. These results are briefly discussed in view of an amplifier operation combined with ultrafast all-optical switching.  相似文献   

10.
Cerium-activated silica (SiO2) glasses were prepared by plasma torch chemical vapor deposition (CVD). In Ce-doped SiO2 glasses, most Ce exists as Ce4+ ions; the remaining small amount of Ce3+ ions exhibits a broad fluorescence spectrum with a large Stokes shift, ∼9600 cm-1, from the excitation spectrum peak of 324 nm. Aluminum and phosphorus codoping considerably increases the Ce3+ ratio and shifts the peaks of both spectra to shorter wavelengths. P codoping is the more effective way to achieve this result and in some cases produces an absorption spectrum similar to that of a Ce-doped phosphate glass. These findings are consistent with the solvatiorn shell model for codoping, as previously proposed. To codope P, a soot remelting method was devised to deal with the highly volatile P2O5.  相似文献   

11.
A novel heavy-metal chalcogenide glass doped with a high dysprosium ion (Dy3+) concentration was prepared by the well-established melt–quenching technique from high-purity elements. The results show that when Cadmium (Cd) is introduced into chalcogenide glass, the concentration of Dy3+ ions doped in GeGaCdS glasses is markedly increased, the thermodynamic performance improves, and the difference between T g and T x is >120°C. The Vickers microhardness is also modified greatly, about 245 kgf/mm2. The optical spectra indicate that all absorption and emission bands of Dy3+ are clearly observed and red-shifted with increasing Dy3+ concentration.  相似文献   

12.
Dy-α-sialon and β-Si3N4 materials containing Dy-oxynitride glass were hot pressed at 1800°C for 1 h. The luminescence spectra of Dy3+ in these samples were compared when excited at 350 nm. The results showed that two strong emission bands in the region 470–500 nm and 570-600 nm, associated with the 4F9/26H15/2 and 4F9/26H13/2 transitions of Dy3+ ions, were observed in Dy-α-sialon. However, no emission peak was detected from the β-Si3N4 sample, despite it containing the same amount of Dy3+ cations. This proved that only the Dy3+ cations in the α-sialon structure, not those in the oxynitride glass, produce the luminescence spectrum.  相似文献   

13.
A chemically durable glass that contains a large amount of phosphorus is useful for in situ irradiation of cancers. It can be activated to be a β-emitter with a half-life of 14·3 d by using neutron bombardment. Microspheres of the activated glass that are injected to tumors can irradiate the tumors directly with β-rays without irradiating neighboring normal tissues. In the present study, P+ ions in various doses have been implanted into a pure silica glass in a plate form at 200 keV. Almost all the implanted phosphorus is present in the inner region of the glass rather than in the surface region, taking the form of phosphorus colloids for all the doses in the range of 5 × 1016-1 × 1018 cm-2. A large number of amorphous phosphorus colloid particles with diameters of 10-150 nm are formed in the silica glass that has been implanted with a dose of 1 × 1018 cm-2; these colloid particles are distributed widely in a layer that is centered at a depth of 200-250 nm. All the investigated glasses hardly release any phosphorus and silicon into water at a temperature of 95°C, even after 7 d. A silica glass that has been implanted with P+ ions at 200 keV with a dose of 1 × 1018 cm-2 is believed to be useful as a radiotherapy glass with sufficient phosphorus content and high chemical durability.  相似文献   

14.
The lower halides of zinc, namely, ZnCl2, ZnBr2, and ZnI2, may act as network formers in glasses that also contain modifying alkali halides such as KCI, KBr, KI, NaI, or CsI. Compositions which contain only Br or I anions are of particular interest because of their extended infrared transmission, which includes the ∼10-μm region, in addition to full visible transparency. A series of modified zinc halide glasses were prepared and characterized by differential scanning calorimetry, middle and far Fourier transform infrared spectroscopy, and polarized Raman spectroscopy. T g values were characteristically low, around 40°C. Bulk glass infrared transmission up to 15 to 20 μm was recorded. The most probable glass structures are discussed and compared to oxide glass models. An attenuation of  0.001 dB/km has been projected as a possible intrinsic minimum for optical fibers operating near ∼6 μm.  相似文献   

15.
Nd3+-ion-doped ZnCl2-based glasses were prepared via the melt-quenching method. The Nd3+-ion upconversion excitation mechanism and the ability to disperse Nd3+ ions into ZnCl2-based glasses were investigated using absorption and upconversion fluorescence spectra of Nd3+ ions. The ZnCl2-based glass that had an average cationic radius equal to the ionic radius of Nd3+ (98 pm) had the greatest ability to disperse Nd3+ ions. The 20KCl·25BaCl2·55ZnCl2glass, which had the average cationic radius nearest to 98 pm, dispersed Nd3+ ions the most, and it had the strongest upconversion fluorescence.  相似文献   

16.
Interfacial reaction kinetics between Ag and ceramic-filled glass (CFG) substrate, containing borosilicate glass, high-silica glass, and alumina, has been investigated at 850°–925°C in different atmospheres. No chemical reaction at the interface of Ag/CFG is found when firing takes place in N2 or N2+ 1% H2. Fired in air, however, an interfacial reaction zone is formed at the interface of Ag/CFG with Ag+ ion diffusing from silver and Al3+ ion dissolving from CFG, and both ions are always coupled together in the reaction zone. Microstructural and chemical analyses show that the reaction zone consists of two distinct layers; one is homogeneous, and the other, heterogeneous. The homogeneous layer, which is adjacent to Ag, is uniform in microstructure with a composition rich in Ag+ and Al3+. The heterogeneous layer is not uniform in microstructure with Si-rich and Ag–Al-rich phases. The reaction zone moves toward CFG with time, forming a heterogeneous layer first and then converting into a homogenous layer when diffusion of Ag+ ion into the CFG becomes significant. The growth kinetics for the homogeneous layer follows a linear rate equation, whereas the heterogeneous layer, a parabolic rate equation. Activation analyses suggest that the formation of the homogeneous layer is controlled by the combination of breakage and formation of M–O bonds, but the heterogeneous layer, by the diffusion of Ag+ ion in the BSG.  相似文献   

17.
Optical Absorption of the Transition Elements in Vitreous Silica   总被引:4,自引:0,他引:4  
The optical absorption of 3d transition elements in fused silica was studied. A series of high-quality silica glasses doped with 0.01 to 0.1 wt% of each transition element (V through Cu) was prepared by a vapor hydrolysis technique. Their optical spectra were measured, and their practical absorptivities were calculated between 200 and 2000 nm. In the proposed waveguide use range (∼ 850 nm), V and Cr appear to absorb most (apract= 2.6 and 1.2 dB/km ppbw−1 (metal), respectively) and Cu the least (apract≃0). Comparisons are made with data for conventional glasses.  相似文献   

18.
The reduction by hydrogen of Fe3+, Ce4+, and Sn4+ in soda-lime-silica glass was found to be diffusion-limited in the glass transition temperature range (500°C). The reduction was studied in fibers by chemical analysis and in bulk samples by optical absorption. Reduction to Fe2+, Ce3+, and Sn2+ proceeds by a reaction of the type H2+2(ɛSi-O)-+2Fe3+→2Fe2++2(ɛSi–OH). Since the rate of reduction by hydrogen is quite similar for these systems and since reduction cannot be accomplished with CO, it is concluded that hydrogen is the diffusing species. A mechanism is developed in which hydrogen diffuses through the glass until it is trapped by a reducible ion.  相似文献   

19.
The gamma-ray-induced optical absorption in a series of cabal (calcium-boron-aluminum) glasses was studied and is interpreted, wherever possible, in terms of structural concepts. A resolution of the observed absorption spectra showed that three Gaussian-shaped bands were induced with their maxima at about 2.3, 3.5, and 5.0 e.v. (550, 350, and 250 mμ). The 2.3-e.v. band decreased in intensity with increasing CaO content, reaching a minimum intensity at a composition corresponding to the four-coordination of about 20% of the boron. Further increase in CaO content was associated with an increase in the intensity of this band. The intensity of the 3.5-e.v. band decreased gradually with increased mole per cent of CaO and increased with increased Al2O3. The 5.0-e.v. band showed an abrupt increase in intensity which corresponded to the appearance of non-bridging oxygens in the network. Replacing Ca2+ by Mg2+, Sr2+, or Ba2+ or replacing Li+ by Na+ or K+ showed that glasses containing large ions of low field strength give less induced absorption than glasses containing small ions of high field strength. A potassium alumina borate glass melted under reducing conditions gave a considerably higher ultraviolet transmission, before irradiation, as compared with the same glass melted under normal conditions. The gamma-induced absorption of these two glasses showed that reducing conditions resulted in a decrease in the intensity of the 2.3- and 3.5-e.v. bands, whereas it caused an increase in the far-ultraviolet-induced absorption. The effect of additions of arsenic, thallium, titanium, germanium, and some rare-earth oxides is discussed.  相似文献   

20.
This paper reports recent progress in the patterning of non-linear optical crystals on the glass surface by laser irradiation. Two techniques for the writing of crystal lines have been developed, i.e., rare-earth (samarium) atom heat processing and transition metal atom heat processing, in which a continuous wave Nd:YAG laser (wavelength: λ=1064 nm) is irradiated to the glasses containing rare-earth (RE: Sm3+, Dy3+) ions or transition metal (TM: Ni2+, Fe2+, V4+) ions. The writing of crystal lines such as β-BaB2O4, Sm x Bi1− x BO3, and Ba2TiGe2O8 showing second harmonic generations has been successful. It is clarified from the azimuthal dependence of second harmonic intensity and polarized micro-Raman scattering spectra that crystal lines consist of highly oriented crystals along the crystal line growth direction. It is also possible to write two-dimensional crystal bending or curved lines by just changing the laser scanning direction. The mechanism of the laser-induced crystallization has been proposed.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号