Si02 film deposition on a glass was made by LPD method (Liquid Phase Deposition). This process involes the deposition and growth of Si02 layer on glass surface while immersing it in hexafluorosilicic acid (H2SiF6) solution supersaturated with silica. In this study, the influence of the impurities and H2SiF6 concentration in the solution on Si02 film properties was investigated by use of SIMS, ICP, Ellipsometry,IRRS and etch rate measurement. The results showed that LPD based Si02 film composition was scarcely affected by the concentration of such impurities as Na, K and Ca contained in the solution. Furthermore it was found that higher H2SiF6 concentration led to Si02 film with lower refractive index and lower etch rate. To have proper understanding of these apparently inconsistent results, the specific role of fluorine contained in the solution and the film was discussed.

Silica aerogels are porous materials whose porosity lies between 98 and 0 %. This large range of porosity is obtained from alcogels of various initial density (by diluting the initial solutions). In order to obtain partially densified aerogels (P.D.A.) the corresponding aerogels are then oxidized and submitted to various isothermal heat treatments performed in a temperature range where the aerogels sinter. Due to their wide porosity scale, PDA are good candidates to be used as host materials. First, the visible light transmission (350-800 nm) against the material density gives information about the microscopic evolution of the porosity. Then, the hydrodynamical properties of the impregnating solutions versus the PDA porosity are studied. The permeability defined as the flow rate of liquid depending on the pressure can afford information about the nature of the porosity. The capillary rise permits characterization of the influence of the surface tension on the penetration of the impregnating liquids. Absorption-desorption measurements give information about the gas flow in these porous materials.

A suitable (concerning long time stability) homogeneous starting silica sol was investigated using the so-called molybdate method and viscosity measurements. For the intendet doping process of AIIIBV-compounds different solutions of zinc salts were added to the silica sols. The long time aging process (polycondensation, gelling) was controlled by the mentioned methods. The semiconductor surfaces were coated by spinning on. Zinc diffusion profiles after different heating regimes were discussed by SIMS and C/V measurements.

In a recently published paper we have described a new manufacturing method of gradient - index pre-forms, optical fibres and some components of glass based guided - wave micro-optics. This method, in the two basic solutions, was called mosaic assembling MA or mosaic assembling defibering (MAD) technology. One the processes involved in manufacturing of some kinds of mosaic optical fibres is glass - sensitizing process. This process consists in application of glass which structurally sensitizes the fibre. This additional sensitizing process is used to optimize the optical (optoelectrical properties of intergrated sensors and all-optical sensors made of single fibers and sensing imageguides. It is also applied to manufacture some selective devices of optical fibre microoptics. The place of sensitizing process during MA/MAD technology was presented in Figure 1.

The sol-gel route to glass offers considerable advantages. Among these the control of composition, low processing temperatures, organical modifications of inorganic polymers leading to a new a class of glass-like materials, the processing of sols to coatings or powders, and the possibilities to structurize glasses are interesting for optoelectronic glasses. Future perspectives of sol-gel processing of optoelectronic glasses as well as some experimental results concerning the state of the art are given.

From our glass polishing process of precision optics we know that its physical-chemical nature frequently leads to a complex interaction of several parameters determining the process and the resulting quality. Surface analysis using SIMS and WDX prove that surface and sharp edge polishing of integrated optics chips has to be watched critically in order to obtain useful parts in a reproducible manner.

Kinetic and energy characteristic properties of fine diamond grinding have been studied, influence of the diamond laer characteristics and processing conditions on the tool self-grinding have been analysed,quantity and quality characteristics of the process have been evalueted. The nature of optical glass surface damage under the action of a single diamond grain,the tool working surface wear mechanism and the effect of a liquid-libricant on these processes have been investigated. The problem of the tool working surface shape stabilization and the required optical surface geometry assurance has been solved for some specific cases (plane,sphere). Optical surface shape final figuring using ion beam machining is discussed.

Thin oxide coatings may be prepared from solutions of alkoxides by the sol-gel method. The procedure consists in the application of a thin liquid layer of solution to the substrate and in the subsequent gelation of this coating, which, upon drying and heating, transforms into a glass or a ceramic. The liquid film may be deposited by different techniques. Many different physical and chemical parameters may influence the thickness, structure and quality of coatings. Among these the chemical composition of the solutions, their reactivity, concentration, density, viscosity and surface tension, the temperature and humidity of the processing environment, the method of application of the coating to the substrate, must be taken into account. In this paper the sol-gel method for the deposition of thin coatings is described from the point of view of the influence of the most important process parameters on the quality and properties of products.

During the mechanical action of an abrasive grain, fracture of the glass surface occurs owing to the formation of primary crack. The interlacing of adjacent cracks the glass reptures at a certain definite distance from the surface. These cracks were removed as a fine fragments during grinding process for optical surface. The simulations of such phenomena such as Prinston and Kachalov's are macro scope point of view which can not explain the mechanical properties of the glass. In this paper, the micro-particle models of grinding crack formation has been builddup. Glass material is assumed to be made form different particles combined together by elastic bound forces. The crack is formed when particles on each layer of the packing be broken or sheared off if the forces between particle contacts exceed the strength of the bound. The computer simulation results could be taken any nymber of particles, arranged in any structure with any elastic bound force. This microscope mechanism provide more insight to the granding phenomenon.

The constant evolution in the decreasing of the fiber price on the market leads manufacturers to reduce the cost of production. Thus, we propose to enhance the preforms production by shortening the manufacture time. In this way, we have replaced the usual bubbling method by a direct evaporation and regulation of chloride. Such a method allow to increase significantly the SiCl4 gas flow. In the other hand, it is also possible to use the direct evaporation method for other processes such as O.V.D, V.A.D... Nevertheless we may pointed out that the direct evaporation method is cheaper than usual one when the SiCl4 mass-flow is greater than 10 g.mn-1.

Due to unique characteristics of gradient-index glass rod as a micro-lens, a variety of micro-optic devices for communication use and new optical components for photo-copiers and facsmile machines have been developed. Ion-exchange techniques which were used to the fabrication of gradient-index micro-lens have also been applied to the fabrication of such new micro-optic glasses as 2-dimensional matrix lenses and optical waveguide circuits. This paper reviews the fabrication processes and applications of gradient-index micro-optic glasses based on ion-exchange techniques.

A 2-D mathematical model of ion diffusion in glass has been developed. It is applied to the Thallium diffusion process used for making optical fiber components. The basic equation used for this modelling is : dC/dt = div (D grad C) - div (μEC). The unknown concentration is the ionic concentration of Thallium in the glass. This law is based on a 1 ion-1 ion exchange and takes into account the thermal diffusion and the diffusion under an electric field. The other physical hypotheses made are the following ones : - the diffusion and mobility coefficients may vary with the Thallium concentration according to any law ; - the model accepts an electrical field variation, in intensity and direction, at any point of the geometrical domain. The calculation method used is the following one - a finite difference method for the solving of the unsteady state diffusion equation, - NEUMANN and DIRICHLET boundary conditions which may vary at each step of the chosen diffusion process. The numerical method (alternate directions) leads to a good approximation of the time scheme, leaving a certain freedom for the choice of the space and time steps.

Two-dimensional refractive index profiles of strip waveguides are directly measured by a refractive near-field technique with a precision of Δn=0.001 and a spatial resolution of 0.8 μm. This technique is nondestructive, and requires minimal sample preparation.

The main aim of this work is to prepare a reliable technology of fibreoptic GRIN matrices of big dimensions and high optical quality. Periodical micro-lens matrices are important construction components of image, guided- wave and information optoelectronics. They are used for building of optical memories, multiplexers and multiwave demultiplexers, network's couplers and nodes. The gradient matrices are a foundation of further development of microoptics. In our laboratory of glass technology we have performed extensive investigations of three groups of glasses specially designed for GRIN matrix microoptics. These glasses were: - cesium glasses of the lowest possible dispersion and the highest possible refractive-index, - low dispersion oxyhalides glasses, - glasses or glass-like materials of the ultimately low dispersion (ultra-low-dispersion glasses). We have investigated the susceptibility of these glasses to ion exchange processes in the context of their chemism, structure, type of ion exchange, ion radii, genesis of technological process etc. These materials have been investigated having in mind their applications in imaging grin matrices. These matrices have been manufactured by a newely developed mosaic-assembling technology (Proc. SPIE 867, 1987). This particular work concerns the first group of glasses. The parameters of lenses and micro-matrices were given and discussed.

Optical waveguides and refractive components can be fabricated in glass by a double ion-exchange: a first NA+ - K+ exchange produces low-index waveguide regions, which are used also as an ionic mask to define the complementary silver-exchanged high-index waveguide component. An experimental analysis of such a process is presented.

Integrated optical components in glass are commonly fabricated by thermal or field assisted ion exchange. We introduce the charge controlled field assisted ion exchange. A reproducible fabrication of optical wave-guides is achieved by using the exchanged charge as the controlling process parameter. The ion current is integrated by a computer controlled unit which stops the process at a preset charge. The charge corresponds to the amount of exchanged ions and a reproducible process is available. Introducing the exchanged charge as the process determining parameter requires a resistant mask material and a special vacuumchuck containing the anode melt and holding the wafer. This is necessary to exclude any leak current during the exchange process. We get resistant masks only when using oxide coatings, which are formed by an anodic oxidation of evaporated aluminium films in a dilute ammonium-tartrat solution [(NH4)2C2H4O6]. It takes only several seconds to fabricate single mode waveguides in glasses such as B-270 (Desag) and BK-7 (Schott) at a temperature of 693 K and an applied electrical field of SO V/mm. Directional couplers are extremely sensitive to parameter deviations . They were used to control the reproducibility of the process. Buried multimode waveguides with a circular cross section have been fabricated by a two step ion exchange in B-270 glass.

A systematic study of the mechanisms which govern the in-depth migration of Ag ions in glasses, in presence of an external field, has been performed, with the aim to create buried waveguides. Ag films, from 60 to 240nm thick, were evaporated on the surface of glasses of different composition. Electric fields ranging from 300 to 1000 V/cm, were applied across the glasses for different times and temperatures. The Ag distribution and glass composition modifications were analyzed using nuclear techniques, as RBS and NRA. Stresses induced by the process were investigated using mechanical microindentation techniques. A comparison between theoretical and experimental profiles has been performed and the importance of the different parameters (electric field, glass temperature, Ag surface layer thickness, process duration) was enlighted.

Scalar finite-element method is used to analyze ion-exchanged channel waveguides. First, the accuracy of the calculation is tested by comparing the theoretical prediction and experimental measurement of cut-off wavelengths. Excellent agreement is observed. Then, this method is utilized to study the mode profile of ion-exchanged channel waveguides with a SiO2:TiO2 cover layer. It is shown that waveguides with circular mode profile can be achieved. Finally, the ion-exchanged waveguides with a grating are studied. the effect of grating parameters on waveguide behavior is investigated.

Commercially available glasses are not optimized for ion exchange in order to fabricate multimode optical waveguides. For most of the glass types the refractive index increase and the waveguide thickness are too small and the loss is increased. Therefore in the last years special glass types have been developed for thallium and silver ion exchange, respectively. By this type of exchange waveguides can be fabricated with refractive index profiles sufficiently matched to that one of 50 μm-graded-index fibers. However, thallium is a highly toxic ion and for silver-sodium exchange a yellow cnuloring of the glasses appears due to reducing impurities as, e. g., As3+, Fe2+ and Sb3+./1/.

A glass etching technology with a HF solution and a chromium mask is presented. The technology allows the etching of semi-circular grooves as deep as 250 μm within a few microns with good surface quality. Two etched substrates can be superposed to obtain a cicular channel that can be filled with plastic to obtain a waveguide. The design of the mask permits the fabrication of guided wave plumbing platforms of light distribution, coupling and intersection circuits compatible with hard clad silica or plastic fibers. The feasability of a coupling platform is demonstrated. The technology also permits the positioning of optical fibers in front of integrated optic circuits.

Silver ion-exchange is used to make waveguides in neodymium-doped lithium-silicate glass. Refractive index change and diffusion coefficient due to ion-exchange are determined. It is observed that silver ion-exchange does not influence the emission wavelength of neodymium-doped glass. Fabrication procedure to achieve rare-earth waveguide lasers is discussed.

The influence of growth defects on optical properties of Lill crystals in exciton region is considered. Lithium hydride crystals consist of ions having S2, S2 electronic configuration. Therefore, LiH belonging to the NaC1 crystal modification differs from typical alkali-halids compounds with p6, p6 symmetry of an electronic subsystem. The densely stacked forecentered anion sublattice with S2-valent electrons forms a wide (about 6 eV) valent zone and determines the behaviour of electronic excitation in LiH. The bottom of the transmission zone is formed by p6-states of lithium ions. The conversion of S and p electron valent levels is affected by S-valent states of hydrogen ions.

The development of optical networks is effective and creates a need for passive components. Integrated optics techniques, with photolithography process, allow components with reproducible performances. Among integrated optics techniques, ion-exchange in glass is interesting and gives good results. The waveguides are obtained in a single step ion-exchange process, in a commercial glass, down to a depth of 8 μm, with a difference of refractive index of 0.007. The attenuation of the elementary guide is characterized by measuring the insertion loss in a line of fiber. The propagation loss of the guide is 0.15 dB/cm. Coupling losses are about 0.5 dB per fiber. The BPM (Beam Propagation Method) is used for designing the mask of a 16 ports splitter. The splitter is characterized with fibers at both the input and output sides. The 16 ports splitter presents excess loss of 4 dB.

Optical waveguides are formed in glass when dopant ions such as Ag+, K+, Tl+, Cs+ replace alcalin ions already present in the glass (typically Na+ or K+). Part of the refractive index increase is due to the higher polarizability of dopant ions. However this substitution leads to a mechanical stress field, as the exchanged species have different ionic radii (Table 1) and a corresponding elasto-optically induced index change (which can be either positive or negative and can therefore modify the index profile). In certain applications, this stress induced birefringence can be useful (i.e. to allow polarization separation in a proximity coupler, to provide strong polarization maintenance on an optical chip), in others, it can be a nuisance (polarization sensitivity in proximity coupler based on wavelength demultiplexers, multiplexers).

Single-mode channel waveguides with a wave propagation loss below 0.1 dB/cm and good matching to the profile of the single-mode fiber can be manufactured by means of two-step field-assisted Cs+-K+ ion-exchange in BGG 21 glass. This technique has been used in the manufacture of symmetrical lxN (N = 2,4,8) couplers and asymmetrical Y-junctions as power dividers. Dual-channel wavelength-division multi/demultiplexers consisting of symmetrical directional couplers or zero-gap couplers have been built in glass and analyzed. In the 1.2/1.6 μm wavelength range, insertion losses below 2 dB, channel spacings of 50-180 nm, and crosstalk values of 20-35 dB have been attained.

Planar waveguides have been fabricated by thermal and field assisted ion exchange.From those experiments, the diffusion parameters of K+ ion exchange in B1664 glass have been determined, for different values of temperatures. With a numerical simulation program and those parameters, a two steps ion exchange process has been estimated and the shapes of the guides have been predicted. Buried planar waveguides have been fabricated by this process.

Fabrication of optical waveguides into glass substrates by an ion exchange process with silver films as ion sources is described. A brief review of the method is first given. The process is described with emphasis on the controllability of multimode waveguide profiles by the source-controlled nature of the process. Fabrication of single mode waveguides by the method is also discussed.

In this paper we present the interest of hybrid technologies for optoelectronics. In this context we show that silicon based integrated optics has a lot of winning cards both to achieve complex optical circuits and to solve the difficult problems of connection with optical fibers and laser diodes.

Corning Glass Works has developed Polarcor, a high performance glass polarizer for the near infrared region of the spectrum. Products are available in custom and stock shapes covering the range 725 to 1700nm. Polarcor consists of a host glass containing elongated, submicroscopic silver crystals aligned along a common axis. These crystals preferentially absorb the polarization component of light aligned with the elongation axis of the particles. Polarcor polarizers are available in contrast ratios (k1 /k2) from 500 to 10,000, placing them in a performance class with birefringent crystal polarizers. Polarcor offers a broader bandwidth, higher transmittance, higher temperature resistance, better durability and increased contrast ratio when compared to plastic and wire grid polarizers. Acceptance angle, compactness (0.5-1mm thick) and cost are significantly better than cube polarizers. Applications include detectors, optical isolators, infrared sensors, fiber optic devices, and optical data storage devices.

Athermal optical glasses for the tasks of optoelectronics synthesized in various glass systems and referring to various regions of Abbe diagram have been considered. As a main criterion in estimation of athermal character of glasses thermooptical constant is used and for laser glasses P and Q, as well. In connection with a vigorous development of optoelectronics, the requirements to the optical glass have been significantly extended. There was a need in glasses to operate in the short-wavelength UV region of spectrum and IR region, glasses operating in a broad temperature range, glasses with a specific trend of the dispersion curve, glasses with laser properties, light-sensitive properties etc. In fact, it is impossible to confine only to the Abbe diagram, where glasses in "n- " coordinates are represented. At present, we have to deal with several types of such diagrams. One of them is a diagram with the arrangement of glasses, which enable to interprete the decreased wave front distorsions in optical pieces under the impact of thermal loads, the so-called athermal glasses.

Photoluminescence measurements of the 1.9-eV (red) emission were carried out on high-purity silica glasses subjected to y-ray irradiation. The time decay of the 4.8-eV-excited-luminescence indicates that the 4.8-eV absorption and the 1.9-eV luminescence arise at two different defect sites, and that an energy transfer occurs between the two defects. Comparison with electron spin resonance observations suggests that the defect responsible for the 1.9-eV luminescence is the non-bridging oxygen hole center (NBOHC: ≡Si-O). The 4.8-eV absorption band increases when the sample is heated in an oxygen atmosphere prior to y-irradiation, suggesting that the defect responsible is related to some form of excess oxygen. The defect is tentatively identified as a negatively charged non-bridging oxygen (≡Si-0 ) which is formed when a peroxy linkage traps a i-induced electron, (≡Si-0-0-Si≡ + e → ≡Si-0- + •O-Si≡ ). Both the NBOHC and the defect responsible for the 4.8-eV absorption must be present in the glass for the 4.8-eV band excited 1.9-eV luminescence to occur.

The luminescence of several rare-earth ions a s2 ion and a transition metal ion in lanthanum borate glass are investigated and compared with the luminescence of these ions in crystals of composition LaB3O6,with a special stress on the transitions of the broad-band type. The results lead to some general conclusions on the luminescence of activators in glasses. These will be dealt with, and examples will be used to illustrate these conclusions.

New I.R. transmitting TeX glasses belonging to the Te-Se-Br system have been investigated in order to determine the suitable glasses for drawing I.R. optical fibers. The vitreous domain has been studied versus the glass tendency to devitrify. Evolutions of glass temperature, thermal expansion coefficient, band gap optical edge for the bromide glasses are presented versus compositions.

Glasses based on fluorides are gaining importance because of their special optical properties. These glasses generally have low refractive indices and low dispersions together with low nonlinear refractive indices. Fluorophosphate glasses, moreover, possess anomalous partial dispersions, making them desirable for optical lens designs that reduce the secondary spectrum. In the present investigation a study on a series of five stable glasses which transmit radiation to wavelengths as low as 200 nm is presented. Samples were prepared from 7 kg castings. The properties of the resulting glasses are compared to commercial oxide glasses and crystals. The dispersion and refractive indices in the ultra-violet spectral region of these experimental glasses range between the values for CaF2 and crystalline SiO2. Optical properties such as internal transmittance, UV-cuton, IR-transmission, refractive indices and dispersions at wavelengths in the ultraviolet spectral region are reported for the UV-transmitting glasses. In addition, the glasses were characterized by their physical properties including: transformation temperature, softening point, coefficient of thermal expansion, thermal conductivity, Young's modulus, and Poisson's ratio.

The thermally stimulated polarization and depolarization current (TSPC/TSDC) technique is used to study the alkali ion motion in the alkali alumino-silicate glasses. One or two TSDC peaks were observed. The mechanism of polarization responsible for the TSDC peaks and mechanism of conduction are discussed.

Electron spin resonance in the spectral region about g=4, believed to be due to a triplet state, is investigated in y-irradiated high-purity silica glasses. The signal in this spectral region was first reported by Griscom, who attributed it to a cavity-like triplet state formed by chlorines. The signal near g=4 in the present study is found only in oxygen deficient samples (samples with optical absorption at 5.0-eV and 7.6-eV prior to y-irradiation). One of these oxygen deficient samples contains no chlorine, but instead contains florine. The signal intensities of the triplet are in good agreement with the chlorine or florine contents. These results suggest that the signal is due to a biradical at an oxygen deficient site (≡Si• •Si≡). When the samples are heat-treated in hydrogen atmosphere prior to y-irradiation, the triplet signal disappears, but not when treated with hydrogen at room temperature. This is consistent with the behavior of the oxygen vacancy (judging from the 5.0-eV absorption intensity), which is terminated by hydrogen-treatment at elevated temperature but remains after hydrogen-treatment at room temperature.

In the last few years, metal or semiconductor-doped glasses have been shown to possess attractive nonlinear optical properties. The Kerr nonlinearity of the embedded microcrystallites is enhanced by the local field effect or by the quantum size effect. Preparation, characterization and experimental techniques are described. The main results are then reviewed for both types of materials. For gold-doped glasses, the nonlinear mechanism is fully understood. Semiconductor-doped glasses fall into two categories : larger particles for which the quantum size effect is weak and for which the nonlinear mechanism is mainly band filling and smaller particles exhibiting quantum confinement and behaving as saturable two-level systems ; the importance of phonon broadening has been shown. In all semiconductor-doped glasses, photodarkening and Auger recombination strongly reduce the nonlinear response time.

The electrooptic Kerr effect and its wavelength dispersion have been measured in glasses representing several compositional systems. The measured Kerr effect was large for glasses having large refractive indices, including 1) glasses containing high concentrations of the heavy metals Pb, Bi, and Tl; 2) glasses with high Nb, Ta, and Ti content; and 3) tellurite glasses. Comparison of Xeff(w=w+0+0), obtained from the measured electrooptic data, to values computed from literature values of Xeff(w=w+w-w) suggest an opposition of the electronic and nuclear contributions to the DC effect.

Thermal nonlinearities of several kinds of semiconductor and metallic doped glasses are analyzed and discussed.

Nonlinear optics can play an essential role in the advancement of optical signal processing and computing toward the "Photonics Era". As an example, the optical nonlinearity affects the device's transmission making it intensity-dependent, so that a threshold can be introduced which is necessary for the operation of the logic elements. The study and the characterization of new or enhanced nonlinear optical materials with higher nonlinear coefficients and fast responses is thus attracting an increasing attention. One approach to enhance the nonlinear response of a material is to utilize quantum confinement, and devices based on one-, two-, and three-dimensional confinementhave been proposed and are currently under development: they have been named Quantum Wells, Quantum Wires, and Quantum Dots, respectively.

Using VO(i-0C3H7)3 as the starting material VOx thin films have been prepared on silica glass substrates by the Sol-Gel dip-coating method and the subsequent heat treatment under vacuum conditions. These thin films show a reversible semiconductor-to-metal phase transition at 67°C. The change of transmittance in the near IR region due to the phase transition is as high as 50%. Infrared spectra show that the value of x is close to 2.

The results on the investigation of optical and mechanical properties of Ge-Sn-Se and Ge-Sn-Se-Te glass systems from the point of view of their application for infrared fiber production are discussed. Ge-Sn-Se, Ge-Se-Te and Ge-Sn-Se-Te glasses have been prepared with the purpose of drawing fibers for CO2 laser radiation (λ = 10.6μm). Their optical, mechanical and structural properties have been examined.

A method to derive the concentration profile directly by the refractive index profile measurements was developed for binary silica glasses. Using the Lorenz-Lorentz relation, it is possible to derive the molecular electronic polarizability values at 632.8 nm from the RNF measurements on fibres and EDS concentration measurements on preform discs. Substituting these values a direct relation between the refractive index and the molar fraction can be obtained. A good agreement between the concentration profile derived with our method and the EDS results was observed.

Role of nonstoichiometry on the formation of UV absorption and luminescence bands in high-purity silica is discussed. The 5.0-eV and 3.8-eV bands are observed in "oxygen-deficient" and "oxygen-surplus" silica, respectively. The 5.0-eV band is caused by oxygen vacancies (≡Si-Si≡) and the 3.8-eV band by peroxy linkages (≡Si-0-0-Si≡). Synthesis conditions and thermal history after the synthesis are shown to affect the formation of defects such as oxygen vacancies and peroxy linkages. The 2.7-eV luminescence band observed in "oxygen-deficient" silica is shown to be primarily due to the oxygen vacancies.

A novel method of glass-sealing optical fiber inside sleeves permits coupling the fiber to an optoelectric device light source, while providing hermeticity and optical-signal integrity. The glass-seal development overcomes limitations inherent in epoxy and metal-solder techniques.

The glassy state, structure and some physico-chemical properties of phosphate glasses on the basis Ba(P03)2 have been determined. The synthesis of the glasses was curried out in crucibles of glassy coal and corundum in an electric furnace in argon atmosphere. On the basis of the absorption spectra in infrared and Raman spectra the structural groups occurring in the phosphate glasses were determined. The addition of the oxides of bivalent metals to the glassy metaphosphate of barium leads in the first phase to breaking of chain metaphosphate particles, their decay and to the formation of pyrophosphate particles. The addition of Si02 results in the decrease of the polymerization degree of the aliphatic anions. The effect of replacing the oxides by fluorides and chlorides on the structure and properties of glasses has been also investigated. On the basis of the examinations of phosphate glasses the possibility of their application in fibre optics has been established. The compositions of phosphate glasses intended to be used for the cladding andcore of the optics fibres have been listed and the light pipes produced in the glass works "Bialystok" by the twocrucible method. The properties of the obtained optic fibres are defined.

A new class of far I.R. transmitting glasses has been discovered in the following systems : Te-CI, Te-Br, Te-CI-S, Te-Br-S, Te-l-S, Te-CI-Se, Te-Br-Se, Ted-Se. The ternary glasses are in general very stable against devitrification and moisture. Many of them show very interesting optical properties and potential low losses in the atmospheric window 8-12 μm. Consequently, they can find many applications in thermal imaging, delivery of 10.6 μm emission of CO2 laser etc... These glasses could be used in form of thin films. Vitreous thin films with controlled composition and so with controlled refractive index have been obtained by sputtering. Planar wave guiding structure could be realized without difficulty. The fiber drawing is being in progress and the preliminary results lead to optical losses around 5 dB/m at 10.6 μm for a single fiber. This attenuation can be compared with the best existing glass fibers.

The power of conventional solid-state laser systems is limited by the thermal load of the active material. One possible approach to solve this problem is to utilize a Nd-doped glass fiber as laser medium. We estimate power and efficiency of several fiber laser configurations arranged in a transverse pump-cavity. The calculations are based on single fibers using laser glass LG-760 (8 wt.-% Nd) as core material of the fiber pumped with available sources. One result is that the laser power is limited not necessarily by the length of the fiber but rather by gain saturation and by the damping loss of the fiber. Furthermore there is an optimum fiber length to maximize the efficiency which results in the fact that large efficiencies are correlated with small laser powers and vice versa. For the configurations under consideration, average powers up to 100 W seem to be attainable with an efficiency of 1 % in pulsed operation; on the other hand, maximum efficiencies at optimum fiber length are about 5% with powers of 5... 10W depending on the core diameter. For cw-operation maximum power and efficiency are reduced to about 40 W and 2.5 %, respectively, mainly due to the thermal population of the lower laser level at room temperature.

Phosphate glass compositions with superior properties for operation as active elements in high average power lasers have been developed. Large, high optical quality castings of these new glasses that are free of metallic inclusions have been made by Schott Glass Technologies and by Hoya Optics. The laser requirements, glass development strategy, and the resultant laser and thermo-mechanical properties of the advanced phosphate glasses are analyzed.

Optical absorption spectra of triply-ionized praseodymium, neodymium, erbium and thulium ions in different phosphate and sulphate glasses have been studied in the visible and near infrared regions. From the observed positions, Racah ( E1 ,E and E3 ), spin-orbit (ξ4t) and the configuration interaction (α, β) parameters are evaluated. The Judd-ofelt intensity parameters (Ω2Ω4 & Ω6) are determined from the observed intensities of the absorption bands. From the intensity parameters it is found that in Potassium Phosphate-Sodium Phosphate (PPSP) glasses, the environment sensitive parameter Ω2 increases and the vibration dependent parameter Ω6 decreases in the four rare earth ions in the same sequence.

The very efficient phosphate glasses of high Nd3+ concentration have relatively (compared to YAG) low thermooptical parameters. In the athermal glasses the thermomechanical stress leads to fraction at moderate average pumping already. Slab geometry with higher than 2.1 width to thickness ratio ensures higher fraction threshold than that of a cylindrical rod of the same cross section, but the thermal lensing causes high-pumping rate dependent-divergence. To compensate the lensing in a relatively wide pumping/repetition rate range a cylindrical resonator was used. With cylindrical mirrors the output beam stability was excellent.