MXPA00000153A - Composition for optical waveguide article and method for making continuous clad filament - Google Patents

Abstract

An optical article having a rare earth doped, fluorinated aluminosilicate glass core composition consisting essentially, in mole%, of:SiO2 0-90;GeO2 0-90;Na2O 0-25;Li2O 0-10;K2O 0-25;Rb2O 0-25;Cs2O 0-25;Al2O3 5-40;Ga2O3 5-40;RE2(1)O3 0-40;RE2(2)O3 0-1;Er2O3 0.001-5;Yb2O3 0-5;PbO 0-15;RO 0-20;ZnO 0-10;ZrO2 0-2;TiO2 0-2;Nb2O5 0-10;Ta2O5 0-10;P2O5 0-5;B2O3 0-15;As2O3 0-10;Sb2O3 0-20;Na2Cl2 0-10;Bi2O3 0-5, and up to 15 weight%fluorine in the form of at least one of a fluorinated component of the glass composition and a batch constituent selected from a group consisting of at least one of AlF3, REF3, NH5F2, NaF, Na2SiF6, Na3AlF6.

Description

COMPOSITION FOR AN OPTICAL WAVE GUIDE ARTICLE AND METHOD FOR MANUFACTURING A COATING FILAMENT CONTINUOUS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to a novel center glass composition which is particularly suitable for, but not limited to, optical waveguide signal amplifying articles due, in part, to the flatness of its gain spectrum, and to a method no CVD to manufacture continuous coating filaments. Particularly, the invention relates to a glass composition of fluorinated aluminosilicate fluorinated with rare earths and to a method of glass pieces in tube to make the continuous coating filament such as, for example, optical waveguide fiber and a conductor.

DESCRIPTION OF THE RELATED TECHNIQUE This request is related to a provisional request from E.U.A. with serial number 60/034472, filed January 2, 1997, which is hereby incorporated by reference in its entirety.

Erbium-doped optical amplifiers and, in particular, erbium-impregnated fiber amplifiers, have revolutionized optical telecommunications by providing all high amplification optical amplification with low noise level without the need for costly repeaters. However, current erbium-doped fiber amplifiers are not suitable for the amplification of multiple channels due to the variation of their gain spectrum as a function of wavelength, denoting flatness of gain or lack thereof. In the sense that is used herein, the term "gain flatness" will refer to the change of shape of the gain spectrum over a particular wavelength scale, i.e. a flat gain means substantially equal gain for all lengths wave over the wavelength scale of interest. For erbium, the wavelength scale of interest is from about 1530nm to 1560nm. When the gain spectrum is not sufficiently flat over its wavelength range, multiple channels of different wavelengths are not uniformly amplified, making the high-speed data communication systems inoperable, impractical and profitable The technique teaches that co-impurifying an erbium-doped fiber with AI2O3 increases the solubility of Er and results in a flatter gain spectrum than that exhibited by a pure silica fiber impregnated with erbium. However, the known erbium doped aluminosilicate compositions produce a better flatness gain efficiency of about 27 dB of gain deviation per 100 dB of gain over a 32nm wide band, and are prone to devitrification at high levels, it is say, greater than a% by weight of Al2O3. SiO2 compositions doped with La2? 3 or La2? 3 + AI2O3 have also shown improved gain flatness and rare earth solubility, but the AI2O3 and La2O3 concentrations are all well below 1%, and thus they have a minor effect. Fluoride glasses, for example, ZBLAN (57ZrF4-20BaF2-4LaF3 - 3AIF3-20NaF (% molar)) exhibit good gain flatness and low phonics, but these compositions require pumping at 1480nm due to the conversion effects high, and exhibit increased noise over a 980nm pump. In addition, they are difficult to fiber, can not be spliced by fusion to silica fibers, are prone to devitrification and have a low durability. In addition to gain flatness, the gain provided by the host medium contaminated with rare earth is also a parameter of interest. Larger gains theoretically can be achieved by increasing the concentration of the appropriate rare earth impurifier; however, over a moderate concentration, the grouping of rare earth ions and concentration extinction. The current methods of CVD for the manufacture of fiberglass preforms are somewhat limited by the composition scales of the host glasses. Only moderate amounts of rare earth elements can be incorporated without grouping effects, and volatile components such as alkali and allogens can not be introduced due to their tendency to vaporize during their placement. In addition, other important glass modifiers, for example, alkaline earths, can not be incorporated due to the lack of CVD precursors of high vapor pressure. Even if a glass soot can be deposited by CVD, it must subsequently be consolidated which can lead to the crystallization or loss of glass components with high vapor pressures. The inventors therefore have recognized a need for a glass composition and optical waveguide articles made therefrom, which is suited to high levels of rare earth dopants without clustering to provide high gain.; this provides an improvement in the flatness of gain over conventional compositions; that can be pumped at 980nm for good noise performance; that can be spliced by fusion to conventional silica-based fibers; that the durability of conventional fiber optic waveguides are adequate or exceed; and have a simple manufacturing. The application related to serial number 60/034472 describes a novel glass ceramic composition and devices made from it that exhibit many of the useful requirements described above. However, the inventors have discovered that the composition of the present invention provides such advantages while eliminating the additional ceramification step that is required to manufacture the glass ceramic, and further provides a larger scale of composition of constituents. Thus, there is a need for a method for manufacturing a waveguide optical fiber from a wide variety of glass and glass ceramic compositions, and other articles of continuous coating filaments such as, for example, a conductor , which faces the disadvantages of known methods, and which is more practical, efficient and economical than conventional methods. The method "glass pieces in tube" of the invention allows that almost any glass can be produced by chemical (sol-gel, vapor deposition, etc.) or physical (supply and fusion) techniques, other supply materials in the form granular or powdered ("pieces of glass" as referred to herein), to be economically manufactured in the form of a continuous coating filament. The rapid extinction of this technique allows glasses and unstable glass ceramics to fibrize.

BRIEF DESCRIPTION OF THE INVENTION In order to achieve this and other advantages in accordance with the purposes of the invention, as it is modalized and broadly described, one embodiment of the invention is directed to an optical guidance device that includes a glass center composition of fluorinated aluminosilicate doped with earths weird In one embodiment of the invention, the center composition consists essentially of, in molar%: 0-90 SiO2 0-90 of Ge02 0-25 of Na20 0-10 of Li2O 0-25 of K2O 0-25 of Rb2O 0 -25 of Cs2O 0-40 of AI2O3 0-40 of Ga2O3 0-40 of RE2 (1) 03 0-1 of RE2 (2) 0.001-5 of Er2O3 0-5 of Yb2O3 0-15 of PbO 0-20 of RO 0-10 of ZnO 0-2 of ZrO2 0-2 of TiO2 0-10 of Nb2O5 0-10 of Ta2O5 0-5 of P2O5 0-15 of B2O3 0-10 of As2O3 0-20 of Sb2O3 0-5 of Bi2O3, 0-10 of Na2CI2, and up to 15% by weight of fluorine in the form of a fluorinated component of the glass composition, where RE (1) is Y3 + and / or La3 + and / or Gd3 + and / or Lu3 +; RE (2) is Ce3 + and / or Pr3"and / or Nd3 + and / or Sm3 + and / or Eu3 + and / or Tb3 + and / or Dy3 + and / or Ho3 + and / or Tm3"; R is Ba and / or Ca and / or Mg and / or Sr; (S¡O + GeO 2) is between 40-90% molar; and the amount of (AI2O3 + Ga2O3) > (RO + "alc" 2O + RE2O3), where "ale" is Li and / or Na and / or K and / or Rb and / or Cs. In one embodiment of the invention, fluorine can be delivered as one or more of the following: ALF3, REF3, NH5F2, NaF, Na2SiF6, Na3AIF6. In another embodiment of the invention, the optical guide device has a central region consisting essentially of the composition described above and a region of silicate glass coating adjacent to the center. In one aspect of this embodiment, the coating composition consists essentially, in% molar, in: 90-100 SiO2 0-10 of B2O3 0-10 of P2O5 0-10 of AI2O3 0-10 of GeO2 and 0-10 of S1F4 In related aspects of this mode, the waveguide device is a multiple mode fiber optic waveguide or a single low loss mode. In another aspect of this embodiment the waveguide device is a rare earth doped optical fiber component of a fiber optic amplifier that exhibits a gain flatness of less than 17 dB of gain variation per 100 dB over a band of 32 nm when pumped by a suitable excitation source, and preferably a gain variation between about a gain of 2-16 dB / 100 dB over the chosen wavelength bands between 1525-1565 nm. In another embodiment, the invention is directed to a non-CVD "tube glass tube" method for manufacturing a continuous coating filament, which involves filling a coating tube that is chemically compatible with a core composition, with a supply material. which consists of pieces of glass of the desired finished central composition having a particle size of approximately between 100 and 5,000 μm, where the coating tube composition is more refractory than the center composition (i.e., has a softening point) which is greater than the melting point of the central composition), heating one end of the tube to near its softening temperature in an oven where the center composition within the tube melts, and lengthening the tube in such a way as to stretch the filament from this one. Preferably, the supply material will have a center composition described above and a silicate coating composition. In one aspect of this embodiment, the supply material will be pieces of conductor glass, for example, a superconducting composition. The coating composition may include, for example, silica, calcium aluminate glass, Pyrex®. Those skilled in the art will appreciate that the method of the tube-in-tube method described herein is provided to make axially or axially-graded center filaments by introducing central glass pieces of the chosen composition into the coating tube. This method allows the manufacture of a continuous coating filament having parameters of interest that vary axially (for example, refractive index). Such product can take the unlimited form, for example, of a hybrid impurified active fiber for fiber amplifier applications. Other features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, and may be learned by practice of the invention. The objects and other advantages of the invention will be evident and will be obtained by means of the apparatus and method particularly indicated in the description written in the claims thereof as well as the attached drawings.

It should be understood that both the general description and the following detailed description are by way of example and are intended to provide a further explanation of the invention as claimed. The accompanying drawings are included to provide a greater understanding of the invention and are incorporated in, and constitute a part of, this specification, illustrate the embodiments of the invention and together with the description serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows the 32 nm broadband gain curves optimized for an exemplary composition mode of the invention (thick line) and that of silica purified with conventional alumina (thin line) with the indicated optimized band. Figure 2 is a graph of loss (attenuation) compared to the wavelength of a fiber waveguide in accordance with one embodiment of the invention. Figure 3 shows a delta refractive index graph compared to the radial distance from the center of a multiple mode fiber waveguide embodiment of the invention. Figure 4 shows a delta refractive index graph compared to the radial position from the center for a single mode fiber waveguide mode of the invention.

Figure 5 is a schematic illustration of a method of glass pieces and tube fiberization according to one embodiment of the invention.

DETAILED DESCRIPTION OF A PREFERRED MODALITY OF THE INVENTION A preferred embodiment of the invention is directed to an optical waveguide device having a new fluorinated aluminosilicate glass core composition doped with rare earths, and a non-CVD method to make a waveguide optical fiber having the central composition of the invention and a coating of silicate glass. Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings and in the tables presented herein. In a preferred embodiment of the invention, an optical article has a glass composition consisting essentially of, in molar%: 60-85 SiO2 0-5 GeO2 3-15 Na20 0-10 Li2O 3-15 of K2O 8-27 of AI2O3 0-5 of Ga2O3 0-40 of RE2 (1) O3 0.002-0.1 of Er203 0-1 of Yb2O3 0-10 of PbO 0-15 of RO 0-5 of ZnO 0-2 of Ta2O5 0-2 of B203 0-2 of As2O3 0-2 of Sb2O3 0-4 of Na2Cl2, and up to 15% by weight of fluorine in the form of a fluorinated component of the glass composition, where RE (1) is Y3 + and / or La3 + and / or Gd3 + and / or Lu3 +; R is Ba and / or Ca and / or Mg and / or Sr; (Si02 + GeO2) is between 60-85% molar; and the amount of (Al203 + Ga203) > (RO + "alc" 2O + RE2O3) where "ale" is Li and / or Na and / or K and / or Rb and / or Cs. In a preferred embodiment of the invention, the optical article is an optical fiber waveguide device such as the active fiber component of a fiber optic amplifier, for example, having a central composition as described above and a silicate glass liner. In one aspect of this embodiment, the coating consists essentially, in% molar, in: 90-100 of S¡O2 0-10 of B2O3 0-10 of AI2O3 0-10 of GeO2, and 0-10 of SiF4. Table 1 shows exemplary core glass compositions (all 100% normalized, and all in molar% amounts), in accordance with the embodiments of the invention.

TABLE I The chemical composition of the glass can be varied within a wide range to design both physical and optical properties as well as a gain flatness for the specific application. S1O2 is the main glass former, with higher levels of SiO2 leading to greater stability, viscosity and glass compatibility with conventional fibers (ie, Si02-based fibers), as the coefficient of thermal expansion decreases. refraction, density and liquid temperature. By increasing the amount of SiO2 in the glass, the Er3 * emission reaches that of the conventional Er amplifiers and exhibits lower gain flatness. As with most optical glasses, GeÜ2 has the same paper as SÍO2 and can be completely replaced by SiO2 to increase the refractive index. To optimize gain flatness, the composition must contain more (AI2O3 + Ga2? 3) than ("alc" 2O + RO + RE2O3), otherwise it will result in emission spectra of an alkaline metal silicate similar to Er3 + , leading to a thin and irregular gain spectrum. Fluoride is key to uniformize the gain spectrum and is also useful for drying glass and maintaining a low refractive index for compatibility with conventional fibers. Between 2 and 50% of the fluorine supplied may be lost during melting depending on the composition, fluoride source and melting time and temperature. Pot lids, low humidity, dry supply materials, and low melting temperatures help minimize these losses. Fluorine can be supplied as AIF3, REF3, NH5F2, NaF, Na2SiF6, Na3ALF6, and any other fluorinated component of the composition, up to 15% by weight. The "ale" 2O and RO components increase thermal expansion and fluoride retention, and decrease the solubility of RE. Their amounts and identities can be used to design a refractive index in the manner known to those skilled in the art. They also serve to decrease the liquid temperature of the glass, making it more stable for devitrification. PbO increases the refractive index and decreases the liquid. Other minor components such as ZrO2, T0O2, Nb2O5 and Ta2O5 can also be added to the glass to increase the refractive index. The B2O3 decreases the density of the glass, but also decreases the fluorescence lifetime of Er3 + when it is added in significant amounts, so it is preferably used sparingly. The usual scavenging agents, As2? 3 and Sb2? 3, can be incorporated without altering the effectiveness of the material. Chloride-based bubble removers can also be used and have the added benefit of drying the glass. The glass must be kept dry to prevent the extinction of Er3 * by the phonons O-H. The glass composition of the present invention has a high solubility of rare earths (RE), a high degree of flatness of gain, and provides a superior performance of Er3 + at 1550 nm. Gain flatness variations less than a gain of 17 dB / 100 dB were achieved between 1530 and 1562 nm, with less than 4 dB of noise, in a 4.7 m fiber amplifier using an active fiber waveguide in compliance with one modality of the invention. It achieved more than 20 dB of gain with 95 mW of pumping power at 980 nm. It is believed that glass modifiers are the key to obtaining the flat gain spectra of Er3 +. It is claimed that high levels of (>; 1 mol%) of AI2O3, RE2O3 (RE = Y3 +, La3 +, Gd3 + and Lu3 +), and F increase the intensity of the Er3 + emission around 1540 nm by suppressing the emission 1530 in relation to the emission of long wavelength (> 1540 nm), thus providing a gain spectrum as shown in Fig. 1. Preferably, the concentrations of AI2O3 will be greater than 5 mol% and that of SiO2 will be less than 90 mol% to avoid the space of Liquid-liquid miscibility in the system S¡O2-AI2? 3-RE2? 3. Other optional modifiers such as alkali and alkaline earth metal oxides will also alter the Er3 + gain spectrum and may suppress miscibility. Various optical articles having a fluorinated aluminosilicate glass center contaminated with rare earths in accordance with the embodiments of the invention have been fibrillated with both borosilicate and pure silica coatings. Low loss fibers having an attenuation between about 0.30 and 0.75 dB / m at 1310 nm, as depicted in Figure 2, have been made in multi-mode configurations as illustrated in Figure 3 and in single-mode configurations. as shown in Figure 4. The delta refractive indices of between 0.6 and 2.1% have been achieved as shown in Figures 3 and 4. In an exemplary embodiment, a fiber optic amplifier comprising an active fiber was constructed. in accordance with one embodiment of the invention (table 1, example XI). The active fiber had a concentration of Ei ^ 'of 1.62 x 1020 ions / cc and exhibited a gain of 18 dB over 0.18 m of fiber. The fiber amplifier tube a gain flatness variation of less than 20 dB per 100 dB of gain over the 32 nm band, as shown in Figure 1. The fiber was melt-bonded to a conventional silica-based fiber and showed splice losses of 0.05 to 0.18 dB / splice. Although the invention has been described so far in terms of waveguide optical fiber for a fiber amplifier, those skilled in the art will appreciate that the optical articles contemplated by the invention may also include, but are not limited to, for example, Planar amplifiers, fiber lasers, Faraday rotators, filters, optical insulators and non-linear waveguide fibers. In addition, together with a method embodiment of the invention which will be described below, the manufacture of continuous coating filaments for conductors is contemplated, resulting in, for example, a superconducting wire. Mixed electro-optical materials are also contemplated. A method embodiment of the invention is described for making a continuous coating filament, preferably an optical waveguide fiber, having an elongated central region of the novel glass composition described herein and an adjacent silicate glass coating. to the central region, comprising the steps of a) supplying a central supply material in the form of finished glass pieces with a particle size in the range of about 100 to 5000 μm; b) providing a rigid coating structure, preferably in the form of a tube, that is chemically compatible with the core composition and that is more refractory than the core composition; c) insert the pieces of glass into the coating structure; d) heating one end of the center / coating r in an oven near the softening point of the coating; and f) stretching the coating containing the center in a continuous coating filament. The term "finished glass pieces" herein refers to the final or final center article composition, for example, the novel glass according to the invention, and not to the prior supply or melting of the composition form. Preferably, the central glass pieces are conventionally made by crucible melting, sol-gel, or other known methods. As shown schematically in figure 5, the pieces of glass are loaded inside a tube (coating) of hollow preform. The coating composition is preferably a silicate glass as described herein, however as those skilled in the art will appreciate, it is essentially not limited and can range from pure SiO2 glass to multi-component glass including, for example calcium aluminate glass and Pyrex®. The central glass pieces preferably have a melting point lower than the softening point of the coating, and the difference in thermal expansion between the center and the coating is not so great that it will break the filament. After the liner is filled with the center glass pieces it can be stretched in a coated filament or rod to be coated. The liner tube filled with center glass pieces is supported in a furnace by known means, and is heated to a temperature sufficient to soften the coating glass to stretch it, and to melt and clean the center glass pieces. Preferably, the coating structure is not sealed in any part of it (this does not refer to a temporary closure of the stretched end of the coating structure if necessary) to allow the escape of gases or other byproducts from the molten center. Preferably, the particle size of the glass pieces is on a scale of approximately 100 to 5000 μm to avoid impact and allow gas or other byproducts to escape. The method "pieces of glass in tube" of the invention has greater advantages than the methods of pieces of glass in tube already known for various reasons. Because the process starts with finished pieces of glass, the material is well mixed on a molecular scale and the supply reactions are complete, in such a way that the formation of gas and bubbles is minimized. The glass is already free of small seeds and the large bubbles trapped from the melting of the powder will float rapidly to the top in the molten molten center. The preferred method opens a wide range of compositions for fibrization that have not previously been obtained with CVD, MCVD or PCVD. The method also accommodates large differences in thermal expansion between the center and the cladding materials because the center is not rigidly bonded to the cladding until it is in the form of fiber, when the stresses due to the decoupling of thermal expansion are much less than in a rigid monolithic preform. The porous glass pieces also allow the atmospheric control of the molten material at the stretching temperature. The pressure on the center can be controlled to regulate the diameter of the center, as well as the stretching temperature. Higher stretching temperatures will produce smaller center diameters for the same outer diameter of given fiber, in contrast to conventional preforms where this ratio is fixed once the preform is manufactured. The ratio of the outer diameter (OD) to the inner diameter (ID) of the tube will be approximately the same as the OD / ID of the fiber although, as established, it can be controlled by pressure (positive or negative) applied to the molten core in relation to the exterior of the coating tube. The controlled glass composition and thermal history can be used to generate graduated index profiles. When the center is melted and the coating is softening, the diffusion procedures are relatively fast, so the graduated index profiles can be created in situ. It will be apparent to those skilled in the art that various modifications and variations may be made to the apparatus and method of the present invention without departing from the spirit and scope thereof. In this way, it is intended that the present invention cover the modifications and variations of this invention as long as they are within the scope of the appended claims and their equivalents.

Claims (23)

NOVELTY OF THE INVENTION CLAIMS

1. - An optical article having a glass composition consisting essentially of, in molar%: 0-90 SiO2, 0-90 GeO2, 0-25 Na2O, 0-10 Li2O, 0-25 K2O, 0-25 of Rb20, 0-25 of Cs2O, 5-40 of AI2O3, 5-40 of Ga2O3, 0-40 of RE2 (1) O3, 0-1 of RE2 (2) O3, 0.001-5 of Er2O3, 0-5 of Yb2O3, 0-15 of PbO, 0-20 of RO, 0-10 of ZnO, 0-2 of ZrO2, 0-2 of T¡O2, 0-10 of Nb2O5, 0-10 of Ta2O5, 0-5 of P2O5, 0-15 of B2O3, 0-10 of As2O3, 0-20 of Sb2O3, 0-10 of Na2CI2, 0-5 of Bi2O3, and up to 15% by weight of fluorine form at least one Fluorinated component of the glass composition and a supply constituent selected from a group consisting of at least one of AIF3, REF3, NH5F2 > NaF, Na2SiF6, Na3AIF6) where RE (1) is at least one of Y, La, Gd, and Lu; RE (2) is at least one of Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm; R is at least one of Ba, Ca, Mg, and Sr; (SiO2 + GeO2) is on the scale of (40-90); and (AI2O3 + Ga2O3) > (RO + "ale" 2O + RE2O3) where "ale" is at least one of Li, Na, K, Cs, and Rb.

2. The article according to claim 1, further characterized in that SiO2 is < 90% molar, the AI2O3 is > 5% molar and B2? 3 is < 5% molar.

3. The article according to claim 1, further characterized in that it comprises a center region of said glass composition; and a coating comprising a silicate glass adjacent said center.

4. The article according to claim 3, further characterized in that the coating has a composition consisting essentially of, in molar%: 90-100 of SiO2) 0-10 of B2O3, 0-10 of P2O5, 0-10 of AI2O3 > 0-10 of GeO2, 0-10 of SiF4.

5. The article according to claim 3, further characterized in that said article is an optical waveguide fiber.

6. The article according to claim 5, further characterized in that said wave guide fiber has a loss of < 0.75 dB / m at 1310 nm.

7. The article according to claim 5, further characterized in that said waveguide fiber can be spliced to a conventional silica-based fiber with splice loss of < 0.18 dB / splice.

8. The article according to claim 5, further characterized in that said wave guide fiber is a single mode fiber.

9. The article according to claim 5, further characterized in that said waveguide fiber is a gain means for an optical signal in a given wavelength scale, which exhibits a gain spectrum signal over said scale of wavelength when said medium is pumped by an excitation source, said gain spectrum has a gain variation < 17 dB / 100 dB between 1530-1562 nm.

10. The article according to claim 9, further characterized in that said gain spectrum has a gain variation on a gain scale of 2-16 dB / 100 dB over a chosen wave region in a wavelength band. approximately 1525-1565 nm.

11. The article according to claim 3, further characterized in that said article is a flat wave guide device.

12. A method for making a filament with continuous coating that includes a center and a coating adjacent to said center region, comprising the steps of: a) providing a supply material for center glass pieces having a particle diameter between about 100 and 5,000 μm and a known melting point; b) providing a rigid coating structure having a softening point above the melting point of said center supply material, characterized in that said coating has a composition that is chemically compatible with said center; c) inserting said pieces of glass into said coating structure; d) heating one end of said coating structure containing the center in an oven to near the softening point of said coating, and e) stretching said coating containing the center in a continuous coating filament.

13. The article according to claim 12, further characterized in that the center glass pieces are a glass having a composition consisting essentially of, in molar%: 0-90 of SiO2, 0-90 of GeO2, 0 -25 Na20, 0-10 Li20, 0-25 K2O, 0-25 Rb2O, 0-25 Cs2O, 5-40 AI2O3, 5-40 Ga2O3, 0-40 RE2 (1) O3 , 0-1 of RE2 (2) O3, 0.001-5 of Er2O3, 0-5 of Yb2O3, 0-15 of PbO, 0-20 of RO, 0-10 of ZnO, 0-2 of ZrO2, 0-2 of TiO2, 0-10 of Nb2O5, 0-10 of Ta2O5, 0-5 of P2O5, 0-15 of B2O3, 0-10 of As2O3, 0-20 of Sb203, 0-10 of Na2CI2, 0-5 of Bi203l and up to 15% by weight of fluorine in the form of at least one fluorinated component of the glass composition and a supply constituent selected from a group consisting of at least one of AIF3, REF3, NH5F2, NaF, Na2SiF6, Na3AIF6 , where RE (1) is at least one of Y, La, Gd, and Lu; RE (2) is at least one of Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, and Tm; R is at least one of Ba, Ca, Mg, and Sr; (S¡O2 + GeO2) on a scale of (40-90); and (AI2O3 + Ga2O3) > (RO + "alc" 2O + RE2O3) where "ale" is at least one of Li, Na, K, Cs, and Rb.

14. The method according to claim 13, further characterized in that the coating has a composition consisting essentially of, in mole%: 90-100 of Si? 2, 0-10 of B2O3, 0-10 of P2O5, 0 -10 of AI2O3, 0-10 of GeO2, 0-10 of SiF4.

15. - The method according to claim 12, further characterized in that the coating structure is a tube that is not sealed in any part thereof that is not the stretching end.

16. The method according to claim 12, further characterized in that the center glass pieces are glass ceramic.

17. The method according to claim 12, further characterized in that the center glass pieces are a superconductor.

18. An optical signal amplifier made in accordance with the method of claim 12.

19. An optical insulator made in accordance with the method of claim 12.

20. A laser made in accordance with the method of claim 12. An optical filter made in accordance with the method of claim 12. 22. A single-mode optical waveguide fiber made in accordance with the method of claim 12. 23. A fiber of Multi-mode optical waveguide made in accordance with the method of claim 12.