Abstract: A waveguide comprising a transparent substrate and a metal oxide coating having the disclosed properties on the substrate can propagate light in an attenuated total reflection mode.

Abstract: A dispersion-shifted fiber includes structure configured to effectively reduce nonlinear optical effects and transmission loss caused by structural mismatching. A core region in the dispersion-shifted fiber includes an inner core and an outer core, which are both glass areas. The inner core is doped with a predetermined amount of fluorine, having an average relative refractive index difference &Dgr;n1. The outer core is disposed between the inner core and the cladding region and is doped with a predetermined amount of germanium dioxide, having an average relative refractive index difference &Dgr;n2(&Dgr;n2>&Dgr;n1), such that the viscosity ratio between the inner core and the outer core at a drawing temperature is set within a predetermined range, thereby effectively restraining structural mismatching from occurring at the boundary between these glass regions.

Abstract: A simple method for producing a synthetic quartz glass having excellent homogeneity and high transmittance, which is useful as an optical material in producing steppers equipped with an ArF excimer laser as a radiation source. A method for producing a synthetic quartz glass for use in ArF excimer laser lithography, which comprises irradiating a highly homogeneous synthetic quartz glass containing less than 60 ppb of Na with ultraviolet radiation having a maximum wavelength of 260 nm for not less than the duration expressed by the equation: Y=(80X−1880)/Z wherein X represents an Na concentration (ppb), Y represents the duration of irradiation (hours), and Z represents the illuminance of an ultraviolet radiation on an irradiated surface (mW/cm2).

Abstract: A silica based optical waveguide is described, comprising a substrate, a core waveguide formed thereon, and an over cladding part comprising a silica based glass with a refractive index lowering dopant and a refractive index increasing dopant added, formed on the substrate so as to cover the core waveguide, wherein a segregation layer with a higher concentration of the refractive index increasing dopant is formed in a part of the over cladding part in contact with the substrate and the core waveguide such that at least a part of the refractive index increase in the segregation layer provided by the refractive index increasing dopant with respect to the part of the over cladding part other than the segregation layer is offset by decline of the refractive index by increasing the amount of the refractive index lowering dopant added in the segregation layer and/or adding another refractive index lowering dopant.

Abstract: A clad optical fiber comprising a core of glass, optionally a glass cladding with a lower refractive index than the glass core and a polymeric cladding made of a material having a refractive index smaller than that of the core (and smaller than that of the glass cladding, if any). The polymeric cladding is made of a cured material of a viscosity increased di- or multi-functional (meth)acrylate and a photopolymerization initiator.

Abstract: An optical fiber for use in a fiber Bragg grating and a fiber Bragg grating using the same are provided. The optical fiber includes a core made of a material obtained by adding germanium oxide (GeO2) to silica (SiO2), for guiding light, and a cladding made by adding a material having a negative thermal expansion coefficient to silica (SiO2), the cladding having a refractive index lower than that of the core. Therefore, the change in Bragg wavelength depending on temperature can be minimized by forming the optical fiber using a material having a negative thermal expansion coefficient.

Abstract: The invention reflects discovery of a liquid phase doping technique that, unlike previous techniques, exhibits very little fluorine depletion upon subsequent heating. The invention involves the steps of providing a silica sol comprising a tetraalkylammonium hydroxide and a di-, tri-, or tetraalkylammonium fluoride, the sol having pH of about 10 to about 14, adding a gelling agent to the sol to induce gelation, casting or extruding the sol to form a gel body, and then drying, heat treating, and sintering the body. Advantageously, the fluorine-containing compound is tetramethylammonium fluoride.

Abstract: Abnormal losses outside a reflection band attributable to a mismatch of core field diameters are suppressed. A photo-sensitive fiber comprising a core 1 and a cladding having a cladding inner layer and a cladding outer layer formed in this order around the core, in which at least the core is photo-sensitive to form a grating. The core and cladding inner layer include a photo-sensitive dopant for increasing the refractive index. The core additionally includes a first non-photo-sensitive dopant for increasing the refractive index and the cladding inner layer additionally includes a second non-photo-sensitive dopant for creasing the refractive index.

Abstract: The present invention is directed to a fluorinated rare earth doped glass composition and method for making a glass-ceramic optical article therefrom, e.g. optical fiber waveguides, fiber lasers and active fiber amplifiers, having application in the 1300 nm and 1550 nm telecommunications windows. The inventive compositions include Pr3+ and/or Dy3+ in a concentration range of between 300-2,000 ppmw and Ag+ in a concentration range of between 500-2,000 ppmw; or Er3+ in a concentration range of between 500-5,000 ppmw and Ag+ in a concentration range of between 0-2,000 ppmw. The monovalent silver ion provides an ionic charge balanced glass-ceramic crystal. These compositions exhibit reduced or absent rare earth ion clustering and fluorescence quenching effects in the presence of high concentrations of rare earth ion dopants.

Abstract: The invention relates to an optical waveguide having a core made of one member selected from halide glasses, chalcogenide glasses and oxyhalide glasses. This one member is doped with both of erbium and cerium. The invention further relates to a 1.5 &mgr;m-band optical amplifier having the optical waveguide for amplifying the light. Due to the doping of both erbium and cerium, it becomes possible to provide a highly efficient optical amplifier having low noise and wide band. With this, it becomes possible to construct an optical communication network having high credibility, high capacity and high speed.

Abstract: A side-face illuminating optical fiber comprising a core 1 transmitting therethrough light entering from an incident end of the optical fiber, a cladding 2 made of silica aerogel which covers an outer peripheral surface of the core, a transparent coating layer 3 which covers an outer periphery of the cladding, and an illuminating portion formed at least in a part of an interface between the core and the cladding. The light transmitting though said core radiates through the illuminating portion to the cladding.

Abstract: A Ge--Ga--S-based glass composition having light amplifying characteristics and an apparatus for optical communications using the glass composition are provided. The present invention includes a sulfur-poor Ge--Ga--S based host glass which includes less S than compositions on the composition line of GeS.sub.2 --G.sub.2 S.sub.3 on the ternary phase diagram of Ge--Ga--S, and a rare earth active material doped on the host glass for luminescence and light amplification. Ga of no more than about 10 mol % is included in the host glass. Also, Pr.sup.3+ ions are used as the rare earth active material. Furthermore, for stable vitrification and a blue shift of a short wavelength absorption band, a vitrification stabilizer such as Br and I is added to the host glass.

Abstract: A planar optical device is formed on a substrate (12) and comprising an array of waveguide cores (14) and a cladding layer (16) formed contiguously with the cores. At least one of the array of waveguide cores (14) and the cladding layer (16) is an inorganic-organic hybrid material that comprises an extended matrix containing silicon and oxygen atoms with at least a fraction of the silicon being directly bonded to substituted or unsubstituted hydrocarbon atoms. In accordance with other embodiments of the invention, a method of forming an array of cores comprises the steps of preparing a core composition precursor material; partially hydrolyzing and polymerizing the material; forming an array of waveguide cores under conditions effective to form an inorganic-organic hybrid material that comprises an extended matrix containing silicon and oxygen atoms with at least a fraction of the silicon being directly bonded to substituted or unsubstituted hydrocarbon atoms.

Abstract: Optical waveguides prepared by irradiating selected regions of positive photochromic polymeric materials with actinic radiation are disclosed. The photochromic materials undergo an irreversible photochemical change which results in an increase in the refractive index of light-exposed regions. In addition, the materials exhibit negligible second-order polarizability prior to exposure and excellent nonlinear optical properties after exposure and polarization. Thus, the exposed regions are particularly useful as the core in active waveguides for use in second-order nonlinear optical applications, as well as the core in passive waveguides. In addition, a simple two step process is disclosed for forming optical waveguides from the positive photochromic polymers. Optical structures, such as optical integrated circuits, and optical devices which incorporate the waveguides are also disclosed.

Abstract: Chalcogenide glass fibers having a glass core with two cladding glass layers, the second cladding glass layer having a refractive index lower than that of the core glass and higher than that of the first cladding glass. The core glass does not contain germanium. Glass fiber having this core-cladding structure is mechanically strong and exhibits only small transmission loss of infrared light passing through the fiber.

Abstract: An optical fiber which comprises a coating layer disposed outside a bare optical fiber having a core and a cladding and a grating formed in the core of the exposed bare optical fiber by removing the coating layer and its manufacturing method. The optical fiber is provided with a re-coating layer disposed in the exposed bare optical fiber.

Abstract: A single-mode optical fiber that includes: (a) a core that includes silica and is characterized by a first refractivity that changes upon exposure to actinic radiation of a predetermined wavelength; and (b) a cladding surrounding the core that also includes silica and is characterized by a second refractivity different from the first refractivity that changes upon exposure to actinic radiation of a predetermined wavelength. At least one of the core and the cladding further includes boron, the relative amounts of boron in the core and cladding being selected such that the first refractivity and the second refractivity change by substantially the same amount upon exposure to actinic radiation of a predetermined wavelength.

Abstract: An optical fiber (20) includes a silica-based core (22) which is operative to transmit light and is surrounded by a silica-based cladding (24) having a lower index of refraction than the core (22). A primary coating (26) surrounds cladding (24), and a secondary coating (28) surrounds primary coating (26). Optical fiber ribbon (40) includes a ribbon matrix material (42) which surrounds a plurality of optical fibers (20). Primary coating (26) comprises a photinitiator which has a peak absorbance in a relatively short wavelength UV spectrum. Secondary coating (28) comprises a photinitiator which has a peak absorbance in a relatively long wavelength UV spectrum.

Abstract: Applicants have determined that the temperature sensitivity of long period grating devices is substantially affected by the provision of a polymeric coating over the conventional glass cladding and, in particular, that by providing a polymer overcoating with an appropriately selected index of refraction, one can minimize temperature sensitivity. In a preferred embodiment, the temperature sensitivity of a long period grating written in conventional dispersion-shifted fiber is reduced to 0.40 nm/100.degree. C.

Abstract: An optical fiber comprises a glass core having a core refractive index; a glass primary cladding at least partially surrounding said core, said primary cladding having a primary cladding refractive index lower than said core refractive index; a glass secondary cladding at least partially surrounding said primary cladding, said secondary cladding having a secondary cladding refractive index lower than said core refractive index but higher than said primary cladding refractive index; said glass of said core and said glass of at least part of said primary cladding containing one or more photosensitizing dopants.

Abstract: A coated glass fiber for light transmission consisting of a glass fiber for light transmission and at least one coating layer made of a UV-curing resin, wherein an outermost layer of the coating layer is made of a UV-curing resin having a Young's modulus of at least 100 kg/mm.sup.2 and a change of a cure shrinkage degree of 1% or less after a Young's modulus reaches one tenth of an end Young's modulus, which has good lateral pressure characteristics and low transmission loss.

Abstract: An active single-mode optical fiber has the core made of a rare earth doped non-oxide glass and the cladding made of an oxide glass. The glass of the core has a melting temperature lower than that of the glass of the cladding and lying within the range of the softening temperatures of the latter. In a preferred embodiment the core is made of a chalcogenide glass and the cladding is made of a lead silicate glass. To produce the fiber, a preform, obtained by introducing an element made of the non-oxide glass into the hole of a capillary tube made of the oxide glass, is brought to a temperature lying within the range of softening temperatures of the oxide glass and not lower than the melting temperature of the non-oxide glass, and is drawn. The capillary tube, during the drawing process, serves as a container for the molten glass of the core.

Abstract: Attenuation of an optical signal at the end of an optical fiber is achieved by positioning a high absorption region at the end of the fiber. A first embodiment teaches highly doped wedges within a tapered end of the fiber. The highly doped wedges adjacent the light transmitting core serve to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped wedges are in proximity to the core due to the tapering. The wedges, which are preferably heavily doped with a rare earth such as erbium, absorbs the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface.

Abstract: Oriented gels aliened by controlled stretching during the gel's transition from a heated, extremely viscous, non melting, non flowing state and the cooled solid gel state produces strong gels which are found to have greater tensile strength than gels of the same rigidity which have not been stretched to a selected degree during its heating and cooling histories. Gels which are selectively stretched during its (non melt flowing) heated state and rapidly cooled by flowing air, cold liquid bath or in contact with a cool surface exhibit optical birefringence when viewed under plane-polarized light.

Abstract: Chalcogenide glass fibers are coated with metals. The products have impro bending strength and resistance to UV, visible light, and moisture. The metal coating may be applied by any method, such as dip coating or sputtering. Typical metals include In, Sn, Bi, Pb, Tl, Zn, Cd and C.

Abstract: A cladding-pumped fiber structure is disclosed in which mode mixing of pump light injected into the fiber is induced by index modulation. In one embodiment, the index modulation is created by a stress-inducing region disposed in the cladding which simultaneously maintains the polarization within the core to produce a polarization-maintaining fiber useful for multi-mode and laser applications.

Abstract: Attenuation of an optical signal at the end of an optical fiber is achieved by positioning a high absorption region at the end of the fiber. A first embodiment teaches a highly doped annulus within a tapered end of the fiber. The highly doped annulus about the light transmitting core serves to absorb light at the end of the fiber. The light transmitting core of the fiber is reduced in diameter due to the tapering, causing the field of light to expand beyond the core. The highly doped annulus is in proximity to the core due to the tapering. The annulus, which is preferably heavily doped with a rare earth such as erbium, absorbs the escaping light in sufficient quantities, both in the initial pass through the tapered region and again upon reflection of the light at the end of the tapered region, such that the attenuation of the reflected light is within acceptable limits without regard to the condition of the fiber's end surface.

Abstract: A flexible light pipe consisting of a light-transmitting core, a cladding, and a sheathing is described which, by suitable choice of cladding and sheathing materials, exhibits a combination of good flexibility for bending and shaping whilst retaining good resistance to kinking or other interruptions which can adversely affect transmission of light.

Abstract: A cladding layer on the core of an optical waveguide is subjected to a rapid thermal annealing process preferably either: in a multi-stage furnace in which the waveguide substrate can be transported rapidly on a carriage between stages at different temperatures; or in a quartz chamber adjacent a bank of quartz halogen lamps of low thermal inertia and easily switched rapidly between different intensities of thermal radiation through the chamber.

Abstract: The invention describes two types of multimode optical waveguides having special dip in the refractive index profile of their core providing conditions for propagation of a higher order mode with sharp central peak which field carries considerable part of the mode energy, while the fields of all other modes in the waveguide are mostly concentrated outside of this central peak region. The waveguide of the first type guides the mode only with one central peak while the mode in the waveguide of the second type has also an additional peak at the interface between the waveguide core and cladding providing a possibility to detect any influence on the mode field in its outer region by measuring the signal in the central peak of the mode.

Abstract: A structure for use in forming an optical component and a method of making such a component is described. The structure comprises a non-waveguiding body of optical material having a concentration of a photorefractive-sensitive component in the body such that upon irradiation of a part of the body by a beam of actinic radiation, the refractive index of the irradiated part is increased. The method of making the optical component comprises providing a non-waveguiding body of optical material; providing a concentration of a photorefractive-sensitive component in the body; contacting the non-waveguiding body of optical material with an atmosphere comprising one of hydrogen, deuterium and mixtures thereof; and exposing a part of the non-waveguiding body of optical material to actinic radiation such that the refractive index of the exposed part is increased. Such a structure and method can be used to form symmetrical planar waveguides, optical fiber waveguides and other optical components such as gratings.

Abstract: Polyimides satisfying the requirements (a), (b) and (c) among the requirements described below, polyimides satisfying the requirements (b), (c) and (d), and polyimides satisfying the requirements (a), (b), (c) and (d) are excellent in transparency, isotropy and resistance to cracking (no crack is formed in the formation of a multilayer film, so that the multilayer formation is easy, namely, the polyimides are good in processability) and can give optical parts excellent in optical characteristics:(a) the difference between the refractive index in TE mode and that in TM mode is 0.02 or less,(b) the glass transition temperature (Tg) is 250.degree. C or higher,(c) the optical transmission loss at a wavelength of 0.7 to 1.6 .mu.m is 1 dB/cm or less, and(d) the fluorine content is 22.6% by weight or less.

Abstract: A glass fiber suitable for use in a light amplifier or laser application which includes an inner cylindrical glass core with a substantially uniform layer of a direct band gap semiconductor material surrounding said core, and a substantially uniform layer of an outer glass cladding surrounding said semiconductor layer. The preform from which the fiber is made is also disclosed.

Abstract: Improved single-mode optical waveguide fibers comprising a central core region, surrounded by an inner cladding region through which light at a chosen signal wavelength will propagate to an appreciable degree along with propagation of same in the central core region, the inner core region further surrounded by an outer cladding region, the improvement comprising germanium dioxide in the inner cladding region at a concentration within the range of about 0.005 percent by weight to about 1 percent by weight of said inner cladding region, effective to significantly reduce the concentration of oxygen atoms in the inner cladding region which are available to form defects that cause hydrogen-induced attenuation. Also provided are core preforms, overclad preforms, and processes for making the fibers, core preforms and overclad preforms.

Abstract: The present invention relates to a single-mode optical fiber having a configuration which enables lowering of dispersion slope while securing a sufficient MFD. This single-mode optical fiber has a refractive index profile in which an indent with a sufficient width is provided at the center of its core region. In particular, this indent satisfies the following relationship:a.multidot.(.DELTA.n.sub.2 -.DELTA.n.sub.1)/(b.multidot..DELTA.n.sub.2).gtoreq.0.04when the first core portion in the single-mode optical fiber has a mean relative refractive index difference of .DELTA.n.sub.1 with respect to the cladding portion and an outer diameter of a while the second core portion has a mean relative refractive index difference of .DELTA.n.sub.2 with respect to the cladding portion and an outer diameter of b.

Abstract: An optical integrated circuit wherein the waveguide network is constructed of a passive waveguide and a functional material is used on the functional portions, an optical circuit device which uses transparent electrodes, an optical switch which uses transparent electrodes and a functional portion made of a non-linear optical material, a matrix optical switch which converts inputted and outputted light at an electrical/optical converter element, and an optical integrated circuit or optical circuit device prepared by selective vapor growth of a functional material on desired regions, as well as an organic film growth process by which an organic film is selectively grown on recess walls and an organic film formation process whereby organic CVD or MLD is performed using a chamber divided into multiple regions.

Abstract: The object of the present invention is to provide an absorber glass for FOP having a broad absorption band which extends from ultraviolet region through visible region to near infrared region. The absorber glass of the present invention contains 18 to 40% by weight of SiO.sub.2 and not smaller than 20% by weight of FeO and Fe.sub.2 O.sub.3 in total.

Abstract: This invention provides a method of increasing adhesion of radiation-cured, inner primary coatings on glass optical fibers. A glass optical fiber drawing tower has a controllable variable amperage electron beam for exposing different sections of a glass optical fiber with different amperage levels of electron beam radiation. The different sections of the glass optical fiber after being exposed to the selected amperage levels of electron beam radiation are then coated with an inner primary coating composition which is finally cured by exposure to actinic radiation. Later formed sections of the same glass optical fiber can be exposed to different amperage levels of electron beam radiation and then coated and cured. The different sections of the glass optical fiber which have been coated with an inner primary coating using this method demonstrate correspondingly different degrees of coating adhesion. Reduced levels of adhesion promoter are required for inner primary coating compositions when using this method.

Abstract: A new light-transmitting device using a SCIN glass core and a novel calcium sodium cladding has been developed. The very high index of refraction, radiation hardness, similar solubility for rare earths and similar melt and viscosity characteristics of core and cladding materials makes them attractive for several applications such as high-numerical-aperture optical fibers and specialty lenses. Optical fibers up to 60 m in length have been drawn, and several simple lenses have been designed, ground, and polished. Preliminary results on the ability to directly cast optical components of lead-indium phosphate glass are also discussed as well as the suitability of these glasses as a host medium for rare-earth ion lasers and amplifiers.

Abstract: Known dispersion-compensating (DC) optical fibers typically are sensitive to small changes in fiber parameter (e.g., fiber diameter and/or core refractive index), and thus are difficult to manufacture. The disclosed DC fibers are relatively insensitive to small departures from the nominal fiber parameters, and are therefore more manufacturable. Exemplarily, the nominal refractive index profile of a DC fiber is selected such that the fiber supports LP.sub.01 and LP.sub.02 (and typically one or more further higher order modes), and the dispersion is substantially all in LP.sub.02. The total dispersion is more negative than -200 ps/nm.km over a relatively wide wavelength range. The nominal refractive index profile typically comprises a refractive index "ring" that is spaced from the fiber core.

Abstract: This invention provides an optical waveguide having diffraction gratings with sufficiently high reflectivity, a waveguide member for obtaining the optical waveguide, and a production process thereof. An optical waveguide in which desired diffraction gratings are formed in a core and in a cladding at a predetermined portion by using a waveguide member in which germanium dioxide is added in the core and in the cladding and irradiating the predetermined portion of the waveguide member with interference fringes of ultraviolet light. By this, the optical waveguide according to the present invention reflects guided light throughout the entire mode field region, thus having a high reflectivity.

Abstract: An optical fiber comprises a core 1 extending in a longitudinal direction and a cladding 3 of silica aerogel preferably having a hydrophobic property to provide a high optical transmission efficiency. The silica aerogel of the cladding is prepared by polymerizing a hydrolyzed alkoxysilane before a supercritical drying treatment and is subjected to a hydrophobic treatment before or during the supercritical drying.

Abstract: This invention relates to fluoride glass with a specific composition having wide infrared transmission. A fluoride optical fiber using this fluoride glass can give high efficiency with a low loss. The fluoride optical fiber having a second cladding on the outer periphery of a first cladding can adjust the refractive index of the first cladding suitably.

Abstract: A method for fabricating multi-layer polymer thin film of an electro-optical device which has a qualified multi-layer by using photobleaching characteristics of polymer. A proper time of photobleaching only changes the chemical, mechanical and electrical characteristics of the surface of the thin film without having any influence on characteristics of the device, so that when the multi-layer thin film are formed, such a cracking due to a solvent or melting, cracking due to the difference of mechanical tensile strength between each layer can be prevented, thereby obtaining a clean multi-layer thin film.

Abstract: A method of fabricating a dispersion shifted optical fiber with a smooth annular ring refractive index profile has the steps of heating a quartz tube with an external oxygen or hydrogen burner and supplying the quartz tube with raw materials including SiCl.sub.4, GeCl.sub.4, POCl.sub.3 and CF.sub.4. O.sub.2 is later supplied. Then, the quartz tube is heated in nine passes of decreasing temperature from 1920.degree. C. to 1890.degree. C., so as to deposit a core section. In the nine passes, the quantity of SiCl.sub.4 feed flow decreases from 380 milligrams per minute to 260 milligrams per minute, the quantity of GeCl.sub.4 feed flow increases from 20 milligrams per minute to 195 milligrams per minute, and the quantity of O.sub.2 feed flow is kept constant at 1500 cubic centimeters per minute.

Abstract: This invention relates to a dispersion-compensating fiber which can be drawn at a lower temperature and can further reduce optical transmission loss. This dispersion-compensating fiber comprises a core portion containing a high concentration of GeO.sub.2 and a cladding portion formed around the outer periphery of the core portion. The cladding portion comprises a first cladding containing fluorine or the like as an index reducer, a second cladding having a higher refractive index than that of the first cladding, and a third cladding which becomes a glass region substantially noncontributory to propagation of signal light. In particular, the third cladding contains a desired impurity such that the glass viscosity thereof becomes lower than that of the second cladding or pure silica cladding at a predetermined temperature.

Abstract: This invention relates to a dispersion-shifted fiber containing silica glass as the major component and in which the zero-dispersion wavelength is set to fall within a range of 1,560 nm to 1,580 nm and the mode field diameter with respect to light having a predetermined wavelength is set to 8 .mu.or more. This dispersion-shifted fiber is a single-mode optical fiber capable of decreasing the influence of nonlinear optical effect and having a structure for suppressing an increase in bending loss of the optical fiber, and includes a core region constituted by the first core portion and the second core portion, and a cladding portion. In particular, an outer diameter a of the first core portion and an outer diameter b of the second core portion satisfy at least a relationship 0.10.ltoreq.a/b .ltoreq.0.29.

Abstract: The present invention relates to a dispersion-shifted fiber having a structure for effectively lowering polarization-mode dispersion. This dispersion-shifted fiber is a single-mode optical fiber mainly composed of silica glass and has a zero-dispersion wavelength set within the range of at least 1.4 .mu.m but not longer than 1.7 .mu.m. In particular, at least the whole core region of the dispersion-shifted fiber contains fluorine.

Abstract: A high power laser transmitting fluoride glass fiber of an enhanced 2.94- .mu.m laser damage threshold value is disclosed, in which either of the core with a high refractive index and the cladding with a low refractive index is formed of fluoride glass which contains fluorine (F) as a component but has it substituted with 0 to 4.1 mol % of bromine (Br), chlorine (Cl), or bromine and chlorine. The optical fiber of the present invention may have its core formed of fluoride glass and its cladding formed of fluorine-contained resin, and the core glass has a composition that 70 to 80% of fluorine (F) is substituted with 0 to 4.1 mol % of bromine (Br), or chlorine (Cl), or bromine and chlorine.

Abstract: This invention is directed broadly to transparent glasses exhibiting excellent transmission far into the infrared region of the electromagnetic radiation spectrum, those glasses consisting essentially, expressed in terms of mole percent, of 40-80% Ga.sub.2 S.sub.3, 0-35% RS.sub.x, wherein R is at least one network forming cation selected from the group consisting of aluminum, antimony, arsenic, germanium, and indium, 1-50% Ln.sub.2 S.sub.3, wherein Ln is at least one cation selected from the group consisting of a rare earth metal cation and yttrium, 1-45% MS.sub.x, wherein M is at least one modifying metal cation selected from the group consisting of barium, cadmium, calcium, lead, lithium, mercury, potassium, silver, sodium, strontium, thallium, and tin, and 0-10% total chloride and/or fluoride. Glass compositions consisting essentially, expressed in terms of mole percent, of 5-30% Ga.sub.2 S.sub.3, 0-10% R.sub.2 S.sub.