Optical properties and local structure of Dy^(3+)-doped chalcogenide and chalcohalide glasses

Dy^3＋-doped Ge-Ga-Se chalcogenide glasses and GeSe2-Ga2Se3-CsI chalcohalide glasses were prepared. The absorption, emission properties, and local structure of the glasses were investigated. When excited at 808 nm diode laser, intense 1.32 and 1.55 μm near-infrared luminescence were observed with full width at half maximum （FWHM） of about 90 and 50 nm, respectively. The lifetime of the 1.32 μm emission varied due to changes in the local structure surrounding Dy^3＋ ions. The longest lifetime was over 2.5 ms, and the value was significantly higher than that in other Dy^3＋-doped glasses. Some other spectroscopic parameters were calculated by using Judd-Ofelt theory. Meanwhile, Ge-Ga-Se and GeSe2-Ga2Se3-CsI glasses showed good infrared transmittance. As a result, Dy^3＋-doped Ge-Ga-Se and GeSe2-Ga2Se3-CsI glasses were believed to be useful hosts for 1.3 μm optical fiber amplifier.

Visible to deep ultraviolet range optical absorption of electron irradiated borosilicate glass

To study the room-temperature stable defects induced by electron irradiation, commercial borosilicate glasses were irradiated by 1.2 MeV electrons and then ultraviolet（UV） optical absorption（OA） spectra were measured. Two characteristic bands were revealed before irradiation, and they were attributed to silicon dangling bond（E＇-center） and Fe^3＋species,respectively. The existence of Fe3＋was confirmed by electron paramagnetic resonance（EPR） measurements. After irradiation, the absorption spectra revealed irradiation-induced changes, while the content of E＇-center did not change in the deep ultraviolet（DUV） region. The slightly reduced OA spectra at 4.9 eV was supposed to transform Fe3＋species to Fe^2＋species and this transformation leads to the appearance of 4.3 eV OA band. By calculating intensity variation, the transformation of Fe was estimated to be about 5% and the optical absorption cross section of Fe2＋species is calculated to be 2.2 times larger than that of Fe^3＋species. Peroxy linkage（POL, ≡Si–O–O–Si≡）, which results in a 3.7 eV OA band, is speculated not to be from Si–O bond break but from Si–O–B bond, Si–O–Al bond, or Si–O–Na bond break. The co-presence defect with POL is probably responsible for 2.9-eV OA band.

Optical temperature sensor based on up-conversion fluorescence emission in Yb^(3+):Er^(3+) co-doped ceramics glass

yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.

Fabrication,microstructure,and optical properties of nanocrystalline transparent LAST glass ceramics containing CeO_2

In the present research, the effect of CeO2 dopant on the fabrication of transparent lithium aluminosilicate titanate （LAST） glass ceramics was investigated. Nanocrystallineβ-quartz solid solution （s.s.） was observed to be the main phase crystallized in this system. Com-parable refractive indices of the glassy matrix andβ-quartz s.s., as well as the incorporation of very fine grains size were determined as the main reasons for retaining the transparency of the glass ceramics. CeO2 was introduced as a suitable optical agent, playing a role as a network modifier in the glass ceramics, because it does not accelerate the growth process and retards the extended growth of crystals. Optical investi-gations indicate that the Fermi energy level, direct and indirect band gaps, and Urbach energy decrease with increasing nanocrystal content in the glassy matrix of specimens, which can be related to the expansion of conduction band, the enhancement of ionic bonds in the crystal lat-tice, and the enhancement of structural arrangement degree, respectively.

An optical glass plane angle measuring system with photoelectric autocollimator

Optical glass is the most widely used optical material.It is necessary to measure its geometric characteristic quickly and reliably to meet the quality of optical glass.A vision measuring system combining photoelectric autocollimation system with high-precision rotary stage is designed to measure the parallelismand angle of optical glass plane.A novel method is proposed to overcome the difficulty ofmeasuring parallelismof optical glass.The model of parallelism and angle measurement is established and the feasibility is analyzed.The image processing algorithm combining Steger algorithm with the least square method is selected.The uncertainty of angle measurement system for angle measurement is 3.0″.The system can solve the problem of measuring the angle of optical glass with high precision and has important significance for optical system.

Effects of Nb2O5 on thermal stability and optical properties of Er^3＋-doped tellurite glasses

Er^3＋-doped tellurite glasses with molar compositions of xNb2O5 - （14.7 - x）Na2O-10ZnO-5K2O-10GeO260TeO2-0.3Er2O3 （x = 0, 3, 5, 7 and 9） have been investigated for developing 1.5 μm fibre and planar amplifiers. The effects of Nb2O5 on the thermal stability and optical properties of Er^3＋-doped tellurite glasses have been discussed. It is noted that the incorporation of Nb205 （x=5） increases the thermal stability of tellurite glasses significantly. Er^3＋-doped niobium tellurite glasses exhibit a large stimulated emission cross-section （7.2×10^-21 - 10.7×10^-21 cm^2） and the gain bandwidth, FWHM×σ^peak （274 ×10^-28 - 480×10^-28 cm^3）, which are significantly higher than that of silicate and phosphate glasses. In addition, the intensity of upconversion luminescence of the Er3＋-doped niobium tellurite glasses decreases rapidly with increasing Nb2O5 content. As a result, Er^3＋-doped niobium tellurite glasses might be a potential candidate for developing laser or optical amplifier devices.

Deformation Analysis of Micro/Nano Indentation and Diamond Grinding on Optical Glasses

The previous research of precision grinding optical glasses with electrolytic in process dressing （ELID） technology mainly concentrated on the action of ELID and machining parameters when grinding, which aim at generating very ＂smoothed＂ surfaces and reducing the subsurface damage. However, when grinding spectrosil 2000 and BK7 glass assisted with ELID technology, a deeply comparative study on material removal mechanism and the wheel wear behaviors have not been given yet. In this paper, the micro/nano indentation technique is initially applied for investigating the mechanical properties of optical glasses, whose results are then refereed to evaluate the machinability. In single grit diamond scratching on glasses, the scratching traces display four kinds of scratch characteristics according to different material removal modes. In normal grinding experiments, the result shows BK7 glass has a better machinability than that of spectrosil 2000, corresponding to what the micro/nano indentation vent revealed. Under the same grinding depth parameters, the smaller amplitude of acoustic emission （AE） raw signals, grinding force and grinding force ratio correspond to a better surface quality. While for these two kinds of glasses, with the increasing of grinding depth, the variation trends of the surface roughness, the force ratio, and the AE raw signals are contrary, which should be attributed to different material removal modes. Moreover, the SEM micrographs of used wheels surface indicate that diamond grains on the wheel surface after grinding BK7 glass are worn more severely than that of spectrosil 2000. The proposed research analyzes what happened in the grinding process with different material removal patterns, which can provide a basis for producing high-quality optical glasses and comprehensively evaluate the surface and subsurface integrity of optical glasses.

Glass Formation and Optical Band Gap Studies on Bi_2O_3-B_2O_3-BaO Ternary System

The glass forming region of Bi2O3-B2O3-BaO ternary system was investigated. A serial of glass samples with high Bi2O3 content in Bi2O3-B2O3-BaO system were prepared by using conventional melting and quenching meld, and the refractive indexes and absorption spectra of samples were measured. It is found that the refractive index of samples as well as the UV absorption increase with the increase of BaO content. According to the Tauc law, optical band gap Eopg which is assumed to be the effective energy band gap Eg is calculated and decreases with the increasing BaO content, and the ratio of Eg/Eopg is 1.3.

Optical Spectroscopy of Er^(3+) and Er^(3+)/Yb^(3+)Co-doped Bi_2O_3-GeO_2-B_2O_3-ZnO Glasses

The （60 - x）Bi2O3 - xGeO2-30B2O3-10ZnO （x = 5, 10, 20, 30 molar percent） glasses doped with Er^3＋ and Er^3＋/Yb^3＋ were fabricated using the melting method. The thermal stability of the glasses was studied with their DTA curves. The results show that the difference between the glass transition temperature and the crystallization onset temperature increases with the increase of GeO2 content, indicating that the thermal stability of the glass has become better. The absorption spectra were recorded and the stimulated emission cross sections were calculated using the McCumber theory. The Ω2, O4, and Ω6 parameters,the transition probability, the radiative lifetime, and the fluorescence branch ratio of Er^3＋ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^（t）（λ = 2, 4, 6） character for optical transitions. The infrared emission of Er^3＋ was measured upon excitation with 970 nm light and the full width at half-maximum （FWHM） was estimated from the emission spectra. The pumping efficiency and the intensity of the emission at the 1.54 μm band of Er^3＋ were enhanced considerably by co-doping Yb^3＋ .

Optical Basicity and Polarizability of Nd³⁺-Doped Bismuth Borate Glasses

This paper reports on different physical and optical properties of Nd3+-doped bismuth borate glasses. The glasses containing Nd3+ in (25 - x)Bi2O3:20Li2O:20ZnO:35B2O3:xNd2O3 (where x = 1, 1.5, 2 mol%) have been prepared by melt-quenching method. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical parameters like dielectric constant, refractive index, ionic concentration, oxygen-packing density, inter ionic distance, polaronradius, reflection loss, energy gap, molar refractivity, molar polarizability, electronic polarizability, optical basicity and field strength are computed. On the basis of the measured values of the density and refractive index, the Nd3+ ion concentration in glasses, the polarizability of oxide ions and optical basicity were theoretically determined. The theoretical value of average electronic polarizability and oxide ion polarizability were calculated by using Lorentz-Lorenz formula. Theoretical optical basicity of the glasses is evaluated based on equation proposed by Duffy and Ingram. The metallization criterion has also been calculated on the basis of refractive index and energy gap. The large value of metallization criterion indicates that the glass materials are insulators. The results obtained predict the nature of bonding in the present glasses and provide basis for developing new nonlinear optical material.

Simulation and Experiment of Double Grits Interacting Scratch for Optical Glass BK7

The elastic-plastic transition regime and brittle-ductile transition regime in scratch process for optical glass BK7 were analyzed based on the Hertzian equation and the stress ratio theory which was proposed by Wei. The interacting scratch process for optical glass BK7 with the grit interval distance as the variable was simulated by the ABAQUS software of finite element simulation based on the energy fracture theory. Double grits interacting scratch test for optical glass BK7 was carried out on the DMG ULTRASONIC 70-5 linear, by which the reliability of finite element simulation was verified. The surface morphology of the workpiece was analyzed by scanning electron microscopy（SEM）, which showed that the width of groove increased obviously with the increase of scratch depth and the grit interval distance. Results of the width of groove were consistent with the simulation results. The subsurface damage layer was analyzed by the method of HF acid etching, which showed that there was an area of cracks intersecting. The scratching force was measured by the threedimensional dynamometer of KISTLER, which showed that the second scratching force increased with the increase of scratching depth and the grit interval distance. The force in the second scratch was smaller than that in the first time, which was consistent with the Griffith fracture theory.

A New Faraday Rotation Measurement Method for the Study on Magneto Optical Property of PbO-Bi₂O₃-B₂O₃Glasses for Current Sensor Applications

MAGNETO-OPTICAL current transformers (MOCT) based on the Faraday Effect provide numerous advantages over the conventional transformers. However the commonly used materials in MOCT are crystals that are very expensive and temperature dependence thus will cause many problems for the output signal. Cost efficient diamagnetic PbO-Bi2O3-B2O3 (PBB) glass system is fabricated in this study, for the aim of obtaining a good candidate glass with high verdet constant and good temperature resistance to replace crystals. A home-made optical bench was setup, calibrated and used for measuring the verdet constant of the fabricated glasses. Glass with composition of 50%PbO-40%Bi2O3-10%B2O3 in mol showed high Verdet constant (0.1533 min/Gauss.cm) and good value of the figure of merit (0.02635 min/Gauss), which can be considered as the ideal candidate for MOCT applications.

Optical Band Gap, Oxidation Polarizability, Optical Basicity and Electronegativity Measurements of Silicate Glasses Using Ellipsometer and Abbe Refractometer

The values of refractive index (n) for silicate glasses (silica, soda lime and borosilicate 7059) are decreased from 1.5119 to 1.5111, 1.5086 to 1.5065 and 1.5296 to 1.5281, respectively;and the optical band gap (Eg) is increased from 9.8 to 9.81 eV, 9.845 to 9.88 eV and 9.56 to 9.58 eV, respectively over the temperature range 295 - 473 K using ellipsometer at wavelength 632.8 nm. While n is decreased from 1.5276 to 1.5274, 1.5074 to 1.5070 and from 1.5283 to 1.5281, respectively;and Eg is increased from 9.59 to 9.592 eV, 9.862 to 9.870 eV, and 9.574 to 9.58 eV, respectively over the temperature range 297 - 322 K using Abbe refractometer at wavelength 589.3 nm. The values of oxide ion polarizability [αo2- (n) and αo2-(Eg)] regarding silica, soda lime and borosilicate 7059 glasses are decreased from 1.3427 to 1.3408, 1.6014 to 1.5941, 1.4329 to 1.4193, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 1.3786 to 1.3764, 1.5991 to 1.5969, 1.4297 to 1.4191, respectively over the temperature range 297 - 322 K using Abbe refractometer. Similarly, the values of optical basicity [A (n) and A (Eg)] of silica, soda lime, and borosilicate 7059 glasses are decreased from 0.4272 to 0.4245, 0.6271 to 0.6224, 0.5045 to 0.4933, respectively over the temperature range 295 - 473 K using ellipsometer;and are decreased from 0.4586 to 0.4567, 0.6256 to 0.6242, 0.5018 to 0.4930, respectively over the temperature range 297 - 322 K using Abbe refractometer. Further, we have found that for silica, soda lime and borosilicate 7059, the values of electronegativity (ξ1av) QUOTE ζ1av) using Zahidnumerical model [based on αO2- (n) and A (n)] are increased from 5.1035 to 5.5504, 4.0393 to 4.830, 4.8143 to 5.0111, respectively over the temperature range 295 - 473 K using ellipsometer;while these values are increased from 5.0657 to 5.2149, 5.0657 to 5.2149, 4.8357 to 5.0111, respectively over the temperature range 297 - 322 K using Abbe refractometer. It is very clear from this research report that both refractive index and optical band gap-based-oxide ion polarizability and optical basicity have the same decreasing trend as the temperature is increased, and this trend indicates that the reported glasses have a very small amount of electronic polarizability. Moreover, this decreasing trend occurs due to the decreasing amount of non-bridging oxygen (NBO) which in turn caused a decrease in refractive index within the silicate glass system at higher temperature. Since the calculated values of electronegativity are found to be in the range 4.0393 - 5.5504 for the reported silicate glasses, so all these glasses have an ionic character. Moreover, low values of optical basicity and of oxide ion polarizability suggest that the silicate glasses are not novel glasses (optical functional glasses) for non-linear optical (NLO) devices or for three dimensional displays.

Glass-forming Ability and Chemical Stability of Magneto-optical Glass Heavily Doped with Rare Earth Oxide

The glass-forming region of B2O3-Al2O3-SiO2 （BAS） glass heavily doped with rare earth oxides was investigated by an effective method, and the chemical stability was investigated by powder method. Influences of rare earth oxides on the glass-forming ability and the chemical stability of the BAS glass were also discussed. The experimental results show that the BAS glass-forming region expands firstly with the increase of the Tb2O3 content up to 30mol% and then shrinks. The acid-resistant capacity of the BAS glass doped with rare earth oxides is the lowest, the water-resistant capacity is secondary, and the alkali-resistant capacity is the best. Besides, the glass chemical stability can be improved by doping appropriate amount of rare earth oxides. Moreover, the stronger the ionic polarization ability of the rare earth ions is, the better the chemical stability of the BAS glass will be.

Evaluation of Correction Algorithm for the Reflectance Measured with Optical Glass

The proposed algorithm for reflectance measured with optical glass has been verified with materials of various forms. The refiectances measured with optical glass (raw), without glass (true) and corrected by the algorithm are compared. The results show that the corrected reflectance agrees very well with true one and their color differences fall below the acceptable limit, which indicates the validity of the correction algorithm. The algorithm could be used not only for fiber-forming materials, but also for powder- forming, granulate-forming, etc.

Scratching and Turning Experiments on Machinability of Optical Glass SF6 in Diamond Cutting Process

To improve the machinability of optical glass and achieve optical parts with satisfied surface quality and dimensional accuracy, scratching experiments with increasing cutting depth were conducted on glass SF6 to evaluate the influence of cutting fluid properties on the machinability of glass. The sodium carbonate solution of 10.5% concentration was chosen as cutting fluid. Then the critical depths in scratching experiments with and without cutting fluid were examined. Based on this, turning experiments were carried out, and the surface quality of SF6 was assessed. Compared with the process of dry cutting, the main indexes of surface roughness decrease by over 70% totally. Experimental results indicated that the machinability of glass SF6 can be improved by using the sodium carbonate solution as cutting fluid.

Research progress of third-order optical nonlinearity of chalcogenide glasses

Chalcogenide glasses （ChGs） are a promising candidate for applications in nonlinear photonic devices. In this paper, we review the research progress of the third-order optical nonlinearity （TONL） of ChGs from the following three aspects： chemical composition, excitation condition, and post processing. The deficiencies in previous studies and further research of the TONL property of ChGs are also discussed.

Effect of Film Thickness on the Optical Parameters and Electrical Conductivity of Te_(10)Ge_(10)Se_(77)Sb_3 Chalcogenide Glass

Several thin films of Te10Ge10Se77Sb3 chalcogenide glass of different thicknesses (250 nm to 400 nm) were prepared by thermalevaporation under vacuum of 133×10-6 Pa (10-6torr). X- ray diffraction analysis showed the amorphicity of the preparedfilms which become partially crystalline by annealing. Transmittance and reflectance measurements in the spectral range of200 nm to 2500 nm have been carried out at normal incidence. The analysis of the absorption coefficient data showed theexistence of indirect transition for the photon energy E in the range 1~3 eV and direct transition for E >3 eV. From thedetermination of the optical constants (n, k), the dispersion of the refractive index has anomalous behaviour in the region ofthe fundamental absorption edge, and followed by the single- effective oscillator approach.The investigated optical parameterssuch as the optical energy gap Eopt, the high frequency dielectric constant εoo, the oscillator position λo, and the oscillatorstrength So, were significantly affected by the film thickness. The characteristic energy gap obtained from the conductivitymeasurements is nearly half the value of that obtained from the optical data as in the case of thickness 400 nm. The activationenergy is 0.65 eV and the indirect optical gap is 1.32 eV.

Variable angle spectroscopic ellipsometry and its applications in determining optical constants of chalcogenide glasses in infrared

The principle of variable angle spectroscopic ellipsometry（VASE） and the data analysis models, as well as the applications of VASE in the characterization of chalcogenide bulk glasses and thin films are reviewed. By going through the literature and summarizing the application scopes of various analysis models, it is found that a combination of various models, rather than any single data analysis model, is ideal to characterize the optical constants of the chalcogenide bulk glasses and thin films over a wider wavelength range. While the reliable optical data in the mid-and far-infrared region are limited, the VASE is flexible and reliable to solve the issues, making it promising to characterize the optical properties of chalcogenide glasses.

Photostimulated Luminescence and Optical Storage in Eu ^(2+)-Doped Fluoride-Oxide Glass Ceramics

Photostimulated luminescence (PSL) phenomenon was observed in a fluoride-oxide glass ceramics doped with Eu 2+. When the UV light irradiated glass ceramic was stimulated by a longer wavelength light, PSL at 447 nm due to the 5d-4f transition of Eu 2+ was observed. The PSl excitation band peaking at 543 nm is due to the electron trap centers which are located either in the Eu 2+-doped crystallites or in the glass; where exactly they are located in is not yet known. The optical storage properties of this kind of glass ceramic were also studied. By comparing with the investigations on PSL phosphor Eu 2+ doped alkali halides, PSL mechanism in glass ceramics which is still an open question and has to be investigated in further experiments was explained.