JPS6158414B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a glass fiber material for infrared transmission that can transmit infrared rays having a wavelength of 2 to 6 μm. Conventional glass fiber materials include glass or plastic containing silicon dioxide (SiO ₂ ) as a main component. However, these materials have a small wavelength region with small transmission loss due to infrared absorption and Rayleigh scattering, and the wavelength range is from 0.6 to 1.7 μm.
It is limited to the visible range to the near-infrared range, and no glass fiber material has been found that can achieve low loss that can be applied in the longer infrared wavelength range. From the viewpoint of materials that are transparent in the infrared wavelength region, glass materials whose main component is a halogen compound, such as BeF ₂ glass or ZnC
Type ₂ glass is known. However, these halide glasses can transmit light up to a longer wavelength region than SiO ₂ -based glasses;
BeF ₂ -based glass is highly toxic and highly deliquescent, while ZnC ₂ -based glass is also highly deliquescent, making it unsuitable for use as a highly reliable optical fiber material. ZrF ₄ as an optical glass other than BeF _2- based and ZnC _2- based
BaF ₂ -NaF series, ZrF ₄ -BaF ₂ -LnF ₃ series (LnF ₃ is a general term for rare earth fluorides), or U.S. Patent No.
ZrF ₄ -BaF ₂ - disclosed in specification No. 4141741
ThF ₄ series and ZrF ₄ -BaF ₂ -UF ₄ series are known. However, in the halide glass of the above-mentioned US Pat. No. 4,141,741, the Th and U components are radioactive elements and pose a practical problem, and this also applies to the other fluoride glasses mentioned above. Glass is unstable to crystallization during the drawing process when manufacturing glass fiber from glass fiber material, making it impossible to obtain a high-quality product. Fluoride optical fiber materials that can be obtained by solving these drawbacks include (1) ZrF ₄ -BaF ₂ -GdF ₃ series glass [Nariyuki Mitaji and Toyotaka Manabe "Fluoride glass fiber for infrared transmission" (S. Mitachi and T.
Manabe, “Fluoride Glass Fiber for Infrared
Transmission”, Japanese Journal of Applied Physics
applied physics), 19 , No. 6, p. 313 (1980)
], it was reported that an optical fiber of 300 dB/Km was obtained, and (2) HfF ₄ (62 mol%) − BaF ₂
(15 mol%) - LaF ₃ (5 mol%) - AF ₃ (2 mol%) - PbF ₂ (10 mol%) - CsF (mol%) [MG Drexhage, B. Bendow, TJ Lorets, J. Mansfield and C.
T. Moynihan, IOOC′81, San Francisco.
Technical Digest (MG Drexhage, B.
Bendow, T. J. Loretz, J. Mansfield and C.T.
Moynihan.IOOC′81, San Francisco, Technical
Digest), M12, 1981], and it is reported that it has been made into a fiber, but its transmission loss has not been reported, and it is still far from being called an optical fiber. 3) _ZrF4
(51.3 mol%) - BaF ₂ (14.5 mol%) - LaF ₃ (4.5
Glass with a composition of (mol%) - LiF (21.4 mol%) - AF ₃ (3.2 mol%) - PbF ₂ (5.0 mol%) [RJ
Zinser and DC Tran, IOOC'81, San Francisco, Technical Digest (RJ
Ginther and DC Tran, IOOOC′81, San
Francisco, Technical Digest), M13, 1981], and it is reported that this can be made into a fiber, but there is no mention of its transmission loss.
Similarly, it is insufficient as an infrared transmission optical fiber. The reason that the transmission loss of the fluoride optical fibers described in these three documents is extremely large is mainly due to
The problem is that these materials tend to crystallize, which increases scattering loss. Therefore, until now, the composition range of glass that can be used as a practical fluoride optical fiber material is still unknown. The present invention was made in view of the above-mentioned current situation, and its purpose is to make a material made of a fluoride that can transmit infrared rays with a wavelength of 2 to 6 μm and is stable against crystallization during drawing. An object of the present invention is to provide a glass fiber material for transmitting infrared rays. The present invention has the following configuration to achieve the above object. That is, to summarize the present invention, the present invention relates to an infrared transmitting glass fiber material, and the first invention is ZrF ₄ 43.5 to 58.1 mol%,
A glass having a composition within the range of 22.8 to 30.4 mol% of BaF ₂ , 2.7 to 3.7 mol% of GdF ₃ and 2.8 to 3.8 mol% of AF ₃ is used as a matrix glass,
~10 mol% CsF, _CaF2 , 4-12 mol%
BeF ₂ , 4-20 mol% CdF ₂ , 4-28 mol%
_SbF3 , 4-8 mol% _YF3 , _LaF3 , _LuF3 , _SnF2
It is characterized by being made of glass doped with a type of compound selected from the group consisting of: Further, the second invention provides ZrF ₄ 48.4 to 60.4 mol%,
BaF ₂ 25.3-31.7 mol%, GdF ₃ 3.0-3.7 mol%, A
It is characterized by containing 0 to 3.8 mol% _{of F3} , 4 to 20 mol% of LiF, and a total of 100 mol%. And the third invention is ZrF ₄ 48.4 to 58.4 mol%,
BaF ₂ 25.3-30.6 mol%, GdF ₃ 0-3.7 mol%, A
A glass having a composition in the range of _3.2 to 3.8 mol% of F 3 and 4 to 20 mol% of CdF ₂ is used as a matrix glass, and 4 to 8 mol% of SbF ₃ , LiF,
It is characterized by being made of glass doped with a type of compound selected from the group consisting of CsF and _YF3 . As shown in the above composition, the glass fiber material of the present invention uses BaF ₂ and ZrF ₄ or a mixture of these two components with GdF ₃ and/or AF ₃ as a matrix glass, and crystals of the glass material for optical fibers. LiF, CsF, CaF ₂ , CdF ₂ , BeF ₂ ,
It is composed of fluoride glass doped with at least one compound selected from the group consisting of SbF ₃ , YF ₃ , LaF ₃ , LuF ₃ and SnF ₂ . In this composition, if the amount of each component is out of the specified range, a glass rod can be obtained by casting into a normal mold, but crystals are likely to occur when drawn, which tends to impede the uniformity of the glass.
It is no longer suitable as a glass fiber material for low-loss infrared transmission. The glass fiber obtained from the glass fiber material comprising the above-mentioned compositional components of the present invention has a wavelength of 2 to 2.
It can transmit infrared rays in the 6 μm band, and it is theoretically possible to achieve a low loss value of 10 ^-3 dB/Km in the wavelength band of 3 to 4 μm. Also, since it does not contain harmful substances, there is no problem of toxicity. Furthermore, since the glass material is composed of a fluoride component that is insoluble in water, it is less affected by OH groups and has excellent water resistance. Furthermore, when a single mode fiber is manufactured from the glass fiber material of the present invention, its diameter can be increased to approximately 40 μm, resulting in a large capacity and extremely low loss fiber that can be easily coupled or connected to a light source. Glass fiber can be obtained. or,
If used in combination with a high-power chemical laser such as a DF laser with a wavelength of approximately 3.8 μm, applications using infrared power transmission such as laser scalpels and laser pencils will become possible.Furthermore, by forming a bundle fiber, it will be possible to obtain infrared images. Direct transmission is also possible. In producing the glass fiber material of the present invention, the powder raw materials of the base glass component are weighed and mixed in the proportions described above, and then at least one of the dopants is added in the proportions within the above range. Weigh, add, and mix, then add a small amount of NH ₄ F/HF, grind and mix, and heat this in a platinum or gold crucible at about 400°C for about 30 minutes to completely fluorinate. , After heating and melting at about 900℃ for about 2 hours,
A glass rod of a predetermined size can be produced by casting in a mold made of brass or the like. Next, the present invention and its effects will be explained in detail with reference to Examples, but the present invention is not limited by these in any way. Example 1 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
BaF ₂ 31.7 mol% (13.75g) - GdF ₃ 3.8 mol%
(2.04g) - ZrF ₄ 60.5 mol% (25g) - AF ₃ 4 mol% (0.644g) Weighed and mixed, then added LiF powder raw material to 4 mol% of the total.
(0.268g) and add (dope)
Then, 10 g of NH ₄ F.HF was weighed and added to this mixture, and the mixture was pulverized and mixed. This was introduced into a metal crucible, heated at 400°C for 30 minutes using an electric furnace to completely fluorinate the raw material, and then heated and melted at 900°C for 2 hours. This was preheated to approximately 250℃ into a three-part brass mold (see Japanese Patent Application No. 55-51752, outer diameter 20mm).
φ, length 130mm, hollow part outer diameter 9mmφ, length 120mm)
Casting in the hollow part of, outer diameter 9mmφ, length
A 100mm glass rod was obtained. The coefficient of linear expansion (α) of this glass rod is 172×10 ^-7 /℃, the glass transition temperature (Tg) is 298.4℃, and the glass deformation temperature (Td) is
The temperature was 311.72° C., and the refractive index (n ²⁰ _D ) was 1.516. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with LiF at a ratio of 8 mol%, 12 mol%, 16 mol%, 20 mol%, and 24 mol%. When these glass rods were jacketed with Teflon FEP and drawn using the zone melting method, fluoride optical fibers with less crystal formation than conventional matrix composition glasses were obtained. but,
It was found that the sample containing 24 mol % of LiF, which was used as a control, was more likely to crystallize.
(For the characteristics of the optical fiber, refer to the explanation below, and the same applies to the following examples.) Example 2 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then doped with CsF powder raw material to make up 4 mol% (1.557 g) of the total, and 10 g of NH ₄ F HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1.
A glass rod with a diameter of 100 mm and a length of 100 mm was obtained. This glass rod had a coefficient of linear expansion of 187.8×10 ^-7 /°C, a glass transition temperature of 299°C, a glass deformation temperature of 322°C, and a refractive index of 1.512. Next, except that the above matrix composition was doped with CsF at a ratio of 8 mol%, 10 mol%, and 12 mol%,
It was confirmed that vitrification could be achieved in the same manner as above. When these glass rods were drawn in the same manner as in Example 1, it was found that the glasses containing 4 mol%, 8 mol%, and 10 mol% of CsF were fluoride optical fibers with less crystal formation compared to conventional matrix composition glasses. Obtained. However, the above performed as a control
On the contrary, it was found that those containing 12 mol% CsF tend to crystallize. Example 3 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, then doped with CaF ₂ powder to give a total amount of 4 mol% (0.81 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 177×10 ^-7 /℃, the glass transition temperature is 313℃, the glass deformation temperature is 331.7℃, and the refractive index is
It was 1.515. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with CaF ₂ at a ratio of 8 mol %, 10 mol %, and 12 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that CaF ₂ was 4 mol% and 8 mol%.
For glasses containing mol% and 10 mol%, fluoride optical fibers with less crystal formation were obtained compared to glasses with conventional matrix compositions. However, it was found that the sample containing 12 mol % of CaF ₂ , which was used as a control, was more likely to crystallize. Example 4 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then doped with CdF ₂ powder to give a total amount of 4 mol% (1.55 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 187×10 ^-7 /℃, the glass transition temperature is 308.9℃, the glass deformation temperature is 326.4℃, and the refractive index is
It was 1.5196. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with CdF ₂ at a ratio of 8 mol %, 12 mol %, 16 mol %, 20 mol %, and 24 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that CdF ₂ was 4 mol % and 8 mol %.
Glasses containing mol%, 12 mol%, 16 mol%, and 20 mol% yielded fluoride optical fibers with less crystal formation compared to glasses with conventional matrix compositions. However, it was found that the sample containing 24 mol % of CdF ₂ , which was used as a control, was more likely to crystallize. Example 5 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportions as in Example 1, then doped with BeF ₂ powder to give a total amount of 4 mol% (0.485 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 163.6×10 ^-7 /℃, the glass transition temperature is 294℃, the glass deformation temperature is 316.6℃, and the refractive index is
It was 1.5128. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with BeF ₂ at a ratio of 8 mol %, 12 mol %, and 16 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that BeF ₂ was 4 mol % and 8 mol %.
Glasses containing mol % and 12 mol % yielded fluoride optical fibers with less crystal formation compared to glasses with conventional matrix compositions. However, it was found that the sample containing 16 mol % of BeF ₂ , which was used as a control, was more likely to crystallize. Example 6 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then doped with SbF ₃ powder to give a total amount of 4 mol% (1.84 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod having an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 177×10 ^-7 /℃, the glass transition temperature is 309.6℃, the glass deformation temperature is 329.7℃, and the refractive index is
It was 1.5085. Next, the same procedure as above was carried out except that the above matrix composition was doped with SbF ₃ at a ratio of 8 mol%, 12 mol%, 16 mol%, 20 mol%, 24 mol%, 28 mol%, and 32 mol%. It was confirmed that it was vitrified. When these glass rods were drawn in the same manner as in Example 1, it was found that SbF ₃ was 4 mol % and 8 mol %.
Glasses containing mol%, 12 mol%, 16 mol%, 20 mol%, 24 mol% and 28 mol% produced fluoride optical fibers with less crystal formation compared to conventional matrix composition glasses. However, the above performed as a control
It was found that those containing 32 mol % of SbF ₃ were more likely to crystallize. Example 7 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then YF ₃ powder was doped to make up 4 mol% (1.51 g) of the total, and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod having an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 190×10 ^-7 /℃, the glass transition temperature is 311.2℃, the glass deformation temperature is 333.8℃, and the refractive index is
It was 1.5167. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with YF ₃ at a ratio of 8 mol %, 10 mol %, and 12 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that the glasses containing 4 mol%, 8 mol%, and 10 mol% of _YF3 had a fluoride ray with less crystal formation compared to conventional matrix composition glasses. fiber was obtained. However, it was found that the sample containing 12 mol % of YF ₃ , which was used as a control, was more likely to crystallize. Example 8 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then doped with LaF ₃ powder to give a total amount of 4 mol% (2.02 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 161×10 ^-7 /℃, the glass transition temperature is 317.9℃, the glass deformation temperature is 342.1℃, and the refractive index is
It was 1.517. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with LaF ₃ at a ratio of 8 mol % and 10 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that the glasses containing 4 mol % and 8 mol % of LaF ₃ produced fluoride optical fibers with less crystal formation compared to conventional matrix composition glasses. Ta. However, it was found that the sample containing 10 mol % of LaF ₃ , which was used as a control, was more likely to crystallize. Example 9 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportions as in Example 1, then doped with LuF ₃ powder to give a total amount of 4 mol% (2.39 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is 165×10 ^-7 /℃, the glass transition temperature is 320℃, the glass deformation temperature is 343℃, and the refractive index is
It was 1.520. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with LuF ₃ at a ratio of 8 mol % and 10 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that the glasses containing 4 mol % and 8 mol % of LuF ₃ yielded fluoride optical fibers with less crystal formation compared to conventional matrix composition glasses. Ta. However, it was found that the sample containing 10 mol % of LuF ₃ , which was used as a control, was more likely to crystallize. Example 10 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportion as in Example 1, and then doped with SnF ₂ powder to give a total amount of 4 mol% (1.616 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. . This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. This glass rod had a coefficient of linear expansion of 197.5×10 ^-7 /°C, a glass transition temperature of 290.8°C, a glass deformation temperature of 315.2°C, and a refractive index of 1.5242. Next, it was confirmed that vitrification was performed in the same manner as above, except that the above matrix composition was doped with SnF ₂ at a ratio of 8 mol % and 10 mol %. When these glass rods were drawn in the same manner as in Example 1, it was found that glasses containing 4 mol % and 8 mol % of SnF ₂ produced fluoride optical fibers with less crystal formation compared to conventional matrix composition glasses. Ta. However, it was found that the sample containing 10 mol % of SnF ₂ , which was used as a control, was more likely to crystallize. Example 11 Powder raw materials of BaF ₂ , ZrF ₄ , AF ₃ , YF ₃ and CdF ₂ were prepared as follows: BaF ₂ 30.6 mol % (13.75 g), ZrF ₄ 58.4 mol % (25 g), AF ₃ 3 mol % (0.644 g) , YF ₃
4 mol% (1.51g) and CdF ₂ 4 mol% (1.55g)
Mix to have a composition of
10 g of NH ₄ F.HF was weighed and added, and the mixture was pulverized and mixed.
This was introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The coefficient of linear expansion of this glass rod is
The glass transition temperature was ^306.2 °C, the glass deformation temperature was 330.4°C, and the refractive index was 1.5166. When a Teflon FEP tube was jacketed on this glass rod and wire was drawn using the band melting method,
YF ₃ and CdF ₂ despite not containing GdF ₃
A fluoride optical fiber with relatively little crystal formation was obtained. Example 12 Powder raw materials of BaF ₂ , ZrF ₄ , GdF ₃ and LiF were
BaF ₂ 31.68 mol% (11g), ZrF ₄ 60.48 mol%
(20g), GdF ₃ 3.84 mol% (1.628g) and LiF 4
They were mixed to have a composition of mol % (0.206 g), and 10 g of NH ₄ F.HF was weighed and added to this mixture, followed by pulverization and mixing. This was introduced into a metal crucible, and completely fluorinated and heated and melted under the same conditions as in Example 1.
Furthermore, in the same manner as in Example 1, the outer diameter was 9 mmφ and the length was 100 mm.
A glass rod of mm was obtained. The coefficient of linear expansion of this glass rod is 197×10 ^-7 /℃, and the glass transition temperature is 285
℃, the glass deformation temperature was 307℃, and the refractive index was 1.526. When a Teflon FEP tube was jacketed on this glass rod and wire was drawn using the band melting method, A
Although it does not contain F ₃ , it contains LiF, so a fluoride optical fiber with relatively little crystal formation was obtained. Examples 13-17 Powder raw materials of BaF ₂ , GdF ₃ , ZrF ₄ and AF ₃ were
They were mixed in the same proportions as in Example 1, and then doped with SbF ₃ powder and CdF ₂ powder to 4 mol % (1.84 g) of the total and 4 mol % (1.55 g) of the total, respectively. Example 13), in another example, SbF ₃ powder was
Mol% (3.68 g) and CdF ₂ powder were doped to 4 mol% (1.55 g) of the total (Example 14),
In yet another example, CdF ₂ powder was used at 4 mol% of the total amount.
(1.55g) and LiF powder at 4 mol% of the total
(0.268 g) (Example 15), and in another example, CdF ₂ powder was doped at 4 mol% of the total amount.
(1.55g) and CsF powder at 4 mol% of the total
(1.557 g) (Example 16), and in another example, YF ₃ powder was doped at 4 mol % (1.51 g) of the total and CdF ₂ powder was doped at 4 mol % of the total.
(1.55g) (Example 17),
Mixtures of different types were prepared, and 10 g of NH ₄ F/HF was weighed and added to each of these mixtures, followed by pulverization and mixing. These were introduced into a metal crucible, completely fluorinated and heated and melted under the same conditions as in Example 1, and further in the same manner as in Example 1 to obtain a glass rod with an outer diameter of 9 mmφ and a length of 100 mm. The physical properties of the obtained glass rod are shown in the table below.

[Table] When a Teflon FEP tube was jacketed on these glass rods and wire was drawn using the band melting method,
A fluoride optical fiber with less crystal formation compared to conventional matrix composition glasses was obtained. The vitrification range of the base glass when carrying out each of the above examples is BaF ₂ 20 to 42 mol%, GdF ₃ 0 to 20
Although the mol% ranges from 48 to 70 mol% for ZrF ₄ and from 0 to 16 mol% for AlF ₃ , it has been found that if a glass outside the composition range of the present invention is used, only a glass that is relatively easily crystallized can be obtained. Next, wire was drawn using the various glass fiber materials obtained in the above examples, and the core diameter was 20μ.
An optical fiber with a plastic clad outer diameter of 300 μm and a fiber length of 100 m was fabricated, and its transmission loss spectrum was investigated. That is, the attached drawing shows the relationship between the wavelength (μm) (horizontal axis) and transmission loss (dB/Km) (vertical axis) of the optical fiber made of the glass fiber material of the present invention (Example 4), that is, the transmission loss. This is a graph showing a specific example of a spectrum, where A shows the absorption of OH groups and B shows the absorption of Teflon FEP as a cladding. In addition, in this test, except for the one doped with BeF ₂ (which makes it difficult for long wavelength light to pass through), it showed almost the same spectrum as in the drawing. As is clear from the graph in the drawing, there are windows at wavelengths of 2 to 2.7 μm and 3.7 μm, and the lowest loss is 80 dB/Km. With conventional fluoride glass materials, scattering loss is high due to crystallization, and low-loss optical fibers have not been obtained. However, with the glass fiber material of the present invention, infrared-transmitting optical fibers with relatively low loss can be obtained. Obtainable. These glasses are theoretically 10 ^-3 dB/Km
It is a material that is expected to have extremely low loss, and further reductions in loss will be possible through improvements such as increasing the purity of raw materials. As explained above, according to the glass fiber material of the present invention, it is possible to obtain an optical fiber with extremely little crystal formation during drawing, which has been a problem in the past.
Furthermore, since it uses a material with low deliquescent properties and low toxicity, it can be used as an optical fiber material for communication, which requires reliability and safety. Furthermore,
Since it is a material that can transmit ultraviolet rays, visible light, and infrared rays of 0.2 to 8 μm, it has the potential to be used as a material for ultra-low loss optical fibers in the new wavelength band of 2 to 4 μm, which avoids the effects of Rayleigh scattering.
In addition, if used as a material constituting a single mode optical fiber, the core diameter should be 20 to 40 μm in the 2 to 4 μm band.
It has many advantages, such as being able to be set as large as μm and making it extremely easy to connect fibers.

[Brief explanation of the drawing]

The drawing is a graph showing a specific example of the transmission loss spectrum of an optical fiber made of the glass fiber material of the present invention.

Claims (1)

[Scope of Claims] 1 A glass having a composition within the range of 43.5 to 58.1 mol% of ZrF ₄ , 22.8 to 30.4 mol% of BaF ₂ , 2.7 to 3.7 mol% of GdF ₃ and 2.8 to 3.8 mol% of AF ₃ is used as the base glass. , CsF of 4 to 10 mol% of the total in the matrix glass,
_CaF2 , 4-12 mol% _BeF2 , 4-20 mol%
_CdF2 , 4-28 mol% _SbF3 , 4-8 mol%
A glass fiber material for infrared transmission, characterized by being made of glass doped with a compound selected from the group consisting of YF ₃ , LaF ₃ , LuF ₃ , and SnF ₂ . 2 ZrF ₄ 48.4-60.4 mol%, BaF ₂ 25.3-31.7 mol%, GdF ₃ 3.0-3.7 mol%, AF ₃ 0-3.8 mol%,
A glass fiber material for infrared transmission characterized by LiF4 to 20 mol% and a total of 100 mol%. 3 ZrF ₄ 48.4-58.4 mol%, BaF ₂ 25.3-30.6 mol%, GdF ₃ 0-3.7 mol%, AF ₃ 3.2-3.8 mol%,
A glass having a composition within the range of 4 to 20 mol% of CdF ₂ is used as a matrix glass, and the matrix glass contains 4 to 8% of the total content.
An infrared transmitting glass fiber material characterized by being made of glass doped with a compound selected from the group consisting of SbF ₃ , LiF, CsF, and YF ₃ in mol%.