CS243697B1 - High refractive index Selo and high spectral transmission suitable especially for optical fiber production - Google Patents

Abstract

Glass with a high refractive index, high spectral transmission in the functional range of 430 to 900 nm and the required long-range thermal expansion with respect to the packaging glass and the frame made of an alloy of iron Pe, nickel Ni, and chromium Cr, is intended primarily for the production of optical fibers and subsequent production of fiber optic plates. The glass contains in a mass concentration of .0 to 14.5% silicon dioxide SiO2, 0.1 to 0.3% aluminum oxide Al2Op <0 to 17.5% lenthanum oxide Da2°3* and* 12.5% boron oxide 26 to 27% barium oxide BaO, 16 to 18% titanium oxide T1O2, 6 to 9% strontium oxide SrO, 0.1 to 3% zirconium oxide ZrO2. High requirements are placed on the purity of the raw materials used to introduce the aforementioned oxides into the glass. The presence of iron impurities Pe in the raw materials is defined.

Description

(54) Selo with high refractive index and high spectral transmission, particularly suitable for the production of optical fibers

Glass with a high refractive index, high spectral transmission in the functional range of 430 to 900 nm and the required long-term thermal expansion compared to the packaging glass and the frame made of an alloy of iron Pe, nickel Ni, and chromium Cr, is intended primarily for the production of optical fibers and subsequent production of rain- ->

fiber optic check.

Glass contains in a mass concentration of .0 to 14.5% silicon dioxide SiO ₂ , 0.1 to 0.3 S aluminum oxide Al _ž Op <0 to

17.5 * lenthanum oxide Da ₂ °3* ^a *

12.5% boron trioxide 26 to 27 * barium oxide BaO, 16 to 18 * titanium dioxide T1O ₂ , 6 to 9 * strontium oxide SrO, 0.1 to 3% zirconium oxide

ZrO ₂ .

High requirements are placed on the purity of the raw materials used to introduce the aforementioned oxides into the glass. The presence of iron impurities Pe in the raw materials is defined.

The invention relates to a glass composition with a high refractive index, high spectral transmission in the functional range of 430 to 900 nm, particularly suitable for the production of optical fibers. Optical fibers consist of core and cladding glass.

By stacking these fibers, fiber optic plates are created, which are usually soldered into a metal frame. A suitable metal frame is an alloy of the iron Fe, nickel Ni and chromium Cr system, which has a coefficient of linear thermal expansion «Ο

20-300 °0· ^{,θ6 = 8} ' ^{5 K} ''·

The glass for these purposes must have such a high refractive index that after coating with the packaging glass the drawn fibre has the highest possible numerical aperture A = 1.0. At the same time, it must, with regard to its use, have the highest possible radiation transmission at a thickness of 5 mm, especially for the wavelength range of 430 to 900 nm, of at least 80%, and must also have a suitable thermal expansion for sealing into a metal frame. The packaging glass used in this case has a coefficient of linear thermal expansion of

20-300 “ 8)3 K

Core glasses for the above-mentioned uses are described in German Patent No. 1,596,946. The glass contains, by weight, 5 to 15% silicon dioxide SiO2, 7 to 15% boron oxide ^Β 2θ3, 4 to 4% calcium oxide CaO, 22 to 30% barium oxide BaO, 2 to 5% tantalum oxide TagOj, 18 to 29% lanthanum oxide LagQp, 8 to 14% titanium oxide TiO2, 2 to 9% zirconium oxide ZrO2, 0 to 4% potassium oxide KgO^, 0 to 4% sodium oxide NagO, 0 to 4% aluminum oxide AlGO^, 0 to 1% lithium oxide LigO.

Coefficient of linear thermal expansion ais

425 ^O C· ^{106 = 9} ' ^{33 to 9} » ⁵⁴ > refractive index n _d = 1.772 to 1.88.

Australian Patent No. 56,990/69 discloses a glass composition containing by weight 19 to 22% boron oxide BgO^, 34 to 38% lanthanum oxide LagO^, 2 to 5% alumina AlgO^, up to 9% zirconium oxide ZrO^, 8 to 15% niobium oxide NbgO^, 4 to 12% tantalum oxide TagO^, 8 to 20% thorium oxide ThO^, less than 6% barium oxide BaO, less than 3% titanium oxide TiO^.

Coefficient of long-distance thermal expansion

425 °0 · ^{1θβ = 6} ' ^{94 to 7} · ^{26 K} '* n _d = 1.85 to 1.91.

Australian patent No. 17 343/67 discloses a glass composition in the weight concentration of 35 to 62% germanium oxide OeOg, 10 to 30% barium oxide BaO, 0 to 25% titanium oxide TiOg, 0 to 15% lanthanum oxide LagO^, 0 to 10% zirconium oxide ZrOg, 0 to 5% tantalum oxide TajO^, 5 to 15% zinc oxide ZnO.

Coefficient of linear thermal expansion oi ₄₂₅ o _c .l0 ⁶ - 6.8 to 7.Θ k ^- ';

n _d » 1.81 to 1.90

Soviet patent No. 192,374 describes a glass composition with a mass concentration of 22 to 30% silicon dioxide SiOg, 30 to 33% lead oxide PbO, 7 to 19% barium oxide BaO, up to .2% cadmium oxide CdO, 2 to 9% zinc oxide ZnO, 3 to 5% titanium oxide T10 ₂ , 2 to 4% boron oxide ^Β 2θ3' 3 to 4 X potassium oxide KgO, less than 3 X calcium oxide CaO and strontium oxide SrO, less than 6 X zirconium oxide Zr0 _2> less than 1 X aluminum oxide AlgO^, 0.3 X arsenic oxide AsgO^, 3 to 7 X lanthanum oxide La ₂ ⁰ 3.

n _d = 1.725 to 1.739.

French patent No. 1,555,790 describes a glass composition in a weight concentration of 5 to 30% silicon dioxide SiO2, 7 to 25% boron oxide BgO2, 5 to 15% lanthanum oxide _La2O3 , 2 to 20% titanium oxide TiO2, 15 to 45% barium oxide BaO, 0 to 15% calcium oxide CaO, 0 to 15% strontium oxide SrO, 0 to 12% aluminum oxide AlG02, 0 to >2% tantalum oxide TSg02, 0 to 8% boron oxide ThO2, 0 to 8% zirconium oxide ZrO2.

Coefficient of linear thermal expansion *£

300 ^ο 0·'° ⁶ “ ⁸ > ^{8 K} ''^; n _d = 1.80.

English patent No. 1,027,958 discloses a glass composition in the weight concentration of 25 to 40% silicon dioxide _Si02 , 0 to 30% boron oxide _B23 , 45% barium oxide BaO, 5 to 40% niobium oxide NbgO^, 0 to 15% calcium oxide CaO and strontium oxide SrO, up to 10% zinc oxide ZnO and cadmium oxide CdO, 0 to 5% sodium oxide NagO and potassium oxide KgO, and lithium oxide LigO, 0 to 36% lanthanum oxide LagOp 0 to

X titanium dioxide TiOg and zirconium oxide ZrO ₂ and hafnium dioxide HfOg and thorium dioxide ThO ₂ , 20 to 40 X niobium oxide NbgO^.

n _d ^x 1.68 to 1.81.

Patent NSR No. 1,496,524 specifies a glass composition in a mass concentration of 5 to 40% niobium oxide NbgO^, 25 to 40% silicon dioxide SiO ₂ , 15 to 45% barium oxide BaO, 0 to 36% lanthanum oxide LagO^, 0 to 15% calcium oxide CaO, 0 to 15% strontium oxide SrO, 0 to 10% zinc oxide ZnO, 0 to 10% cadmium oxide CdO, 0 to 5% sodium oxide NsgO, 0 to 5% potassium oxide KgO, 0 to 5% lithium oxide LigO, the sum of NbgO ₅ and Ta ₂ O ₅ up to 90%, the sum of SiO ₂ and BgO ₃ up to 70%.

n _d = 1.68 to 1.81.

GDR Patent No. 84,899 describes a glass composition in a mass concentration of 0 to 20% silicon dioxide _SiO2 , 0 to 30% boron oxide BgOj, 0 to 15% germanium oxide GeOg, 15 to 30% lanthanum oxide LagO^, 0 to 10% zirconium oxide _ZrO2 , 0 to 25% tantalum oxide ^t ®2°5' ⁰ ®ž 25% niobium oxide NbgO^, 0 to 5% titanium dioxide TiOg, 5 to 25% barium oxide BaO, 5 to 25% calcium oxide CaO, 0 to 5% aluminum oxide AlgOy

Coefficient of linear thermal expansion «6

0-300 °C· ¹⁰⁶ * ⁶ ' ^{8 K} '» n _d = 1.805.

USSR Patent No. 451,646 specifies a glass composition in mass concentration of 10 to 19 X silicon dioxide SiOg, 9 to 14 X boron oxide BgOj, 16 to 23 X lanthanum oxide La ₂ O ₃ , 8 to

X titanium dioxide TiOg, 24 to 33 X barium oxide BaO, 1 to 6 X zirconium oxide

ZrO ₂ , 1 to 11% niobium oxide NbgO^, 1 to 11% tantalum oxide TagOj, 0.5 to 10% germanium oxide GeO ₂ , 1 to 12% cadmium oxide CdO, 0.3 to 3% arsenic oxide n _d = 1.81.

U.S. Patent No. 3,879,207 discloses a glass composed of 4 to 16% by weight of boron oxide BgO^, 10 to 20% silicon dioxide SiO^, 1 to 4% aluminum oxide AljO^, 31 _to ž 35% lanthanum oxide LagO^, 12 to 16% ^barium oxide BaO, 2 to 6% aluminous oxide ZnO, 4 to 8% zirconium oxide ZrO ₂ , 5 to 13% niobium oxide NbgOj, 2 to 10 * tantalum oxide ^τ β2°5'

Coefficient of linear thermal expansion!

30-300 °0·'° ^{6 = 7} ' ^{20 to 7} ' ^{24 K} i' n _d = 1.802 to 1.808.

The listed glasses do not provide the required values of the coefficient of linear thermal expansion for a window with a metal frame, whose

20-300 °C· ^{106 = 8.5 K} ' and the current required values of the refractive index. In most cases, the spectral transmission is not stated. The introduction of tantalum oxides TagO^, niobium oxide NbgO^, thorium oxide ThOg, germanium oxide GeO ₂ and hafnium oxide HfO ₂ makes their production too expensive, while the introduced lead oxides PbO and cadmium oxide CdO are not entirely suitable for the final processing of the glasses.

The above disadvantages are eliminated in the glass composition according to the invention, the essence of which lies in the fact that it contains in a mass concentration of 10 to 14.5% silicon dioxide SiO2, 0.1 to 0.3% aluminum oxide AlG2O3, 16 to 17.5% lanthanum oxide LaG2O3, 11 to 12.5% boron oxide BgO2, ²⁸ to 27% barium oxide BaO, 16 to 18% titanium oxide TiO2, 6 to 10% strontium oxide SrO2, 0.1 to 3% zirconium oxide ZrO2.

The raw materials used to introduce the above oxides into the glass may contain individually, in a mass concentration of iron Fe, a maximum of ground quartz 0.0001%, aluminum hydroxide 0.002%, lanthanum oxide 0.003%, boric acid 0.00006%, barium nitrate 0.00006%, titanium dioxide 0.003%, strontium nitrate 0.00006%, zirconium dioxide 0.002%.

The glass according to the invention, in comparison with known glasses, meets all the requirements placed on its properties and thus increases its functional and utility value. It is suitable, due to its high refractive index and high spectral transmission, primarily for the production of optical fibers.

An exemplary embodiment of the glass according to the invention is described below.

Glass contains in mass concentration 14.2% silicon dioxide _SiO2 , 0.3% aluminum oxide AlO2, 17.4% lanthanum oxide LaO2, 12.4% boron oxide BgO2, ²⁷ % barium oxide BaO, 17.5% titanium dioxide _TiO2 , 8.7% strontium oxide SrO, 2.5% zirconium oxide _ZrO2 .

The spectral transmission of glass in the ultraviolet and visible regions of the spectrum is significantly affected by impurities forming admixtures of the raw materials used, especially coloring iron ions Fe. It is therefore necessary to use raw materials of defined purity, according to the invention, to introduce oxides into the glass.

To prevent the above impurities from contaminating the glass during the preparation of the charge and during melting, it is necessary to exclude contamination with dust impurities present in the air, mix the stock in non-metallic containers, load the stock into the pan with a non-metallic spatula. The glass must be melted in a pan made of very pure platinum Pt, and the glass homogenization must be carried out with a propeller stirrer made of very pure platinum Pt.

For melting glass, it is necessary to set aside a platinum pan including a propeller stirrer and not melt glass of a different chemical composition in it. Glass is melted at a temperature of 1,250 °C, glass is cast into a block at a temperature of 950 °C.

The glass according to the invention has a refractive index n _e - 1.82741, n _d = 1.82144, mean dispersion n^, - n^,, = 0.02568, np - n _c = 0.02529, coefficient of linear thermal expansion oř

20-300 °c ^,1 ° ^{= 8.5 K} radiation transmission for a wavelength of 430 nm at a thickness of 5 mm is 82% and for a wavelength of 900 nm it is 87%. When using a container glass with a refractive index ηθ = 1.52, the numerical aperture A * 1.014. The glass does not crystallize when heated for 4 h in the temperature range of 709 to 972 °C.

In addition to the production of optical fibers and plates for fiber optics, the glass according to the invention can also be used in classical optics, for the production of special optoelectronic elements, etc.

Claims (1)

SUBJECT OF THE INVENTION Glass having a high refractive index and high spectral transmission, particularly suitable for the production of optical fibers, characterized in that it contains from 10 to 14.5% by weight of SiO2, 0.1 to 0.3% by weight of AlgO-16 in the concentration by weight. up to 17.5% of lanthanum oxide LagOj, 11 to 12.5% of boron oxide B BO ^ 26 to 27% of barium oxide BaO, 16 to 8% of titanium dioxide TiOg, 6 to 9% of strontium oxide SrO, 0.1 to 3% zirconium oxide ZrOg, the raw materials by which the oxides are introduced into the glass may contain, individually in an iron Fe concentration by weight, not more than 0.0001% ground quartz, 0.002% aluminum hydroxide, 0.003% lanthanum oxide, 0.00006% boric acid , 0.00006% barium nitrate, 0.003% titanium dioxide, 0.00006% strontium nitrate, 0.002% zirconia.