Glass material and optical fiber

Abstract

The glass material is composed of silica-based glass, contains a halogen element, and contains bromine and / or iodine, and the concentration ratio of a halogen molecule X2 to a halogen ion X-satisfies [X-] / [X2] > = 1.

Description

Technical Field

[0001] The present disclosure relates to a glass material and an optical fiber. This application claims priority based on Japanese Application No. 2022-094169 filed on June 10, 2022, and all the contents described in the Japanese Application are incorporated herein by reference. Background Art

[0002] Bromine and iodine can be used as an up-dopant to increase the refractive index of glass. Patent Documents 1 and 2 disclose optical fibers in which bromine and iodine are doped in the core.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: U.S. Patent Application Publication No. 2020 / 0087195

[0006] Patent Document 2: U.S. Patent Application Publication No. 2020 / 0049881 Summary of the invention

[0007] The glass material according to one embodiment of the present disclosure is a glass material composed of a silica-based glass and containing a halogen element, and contains at least one of bromine and iodine, and the halogen molecules X2 and the halogen ions X - The concentration ratio satisfies [X - ] / [X2]≥1.

[0008] An optical fiber according to one embodiment of the present disclosure comprises: a core composed of silica-based glass and containing a halogen element; and a cladding composed of silica-based glass and surrounding the core, wherein the core contains at least one of bromine and iodine, and in the core, halogen molecules X2 and halogen ions X - The concentration ratio satisfies [X - ] / [X2]≥1. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a cross-sectional view showing an optical fiber according to an embodiment.

[0010] Figure 2 It is a graph showing the relationship between the concentration ratio and the transmission loss.

[0011] Figure 3 It is a graph showing the relationship between the concentration ratio and the transmission loss.

[0012] Figure 4 It is a graph showing the relationship between the concentration ratio and the transmission loss.

[0013] Figure 5 It is a graph showing the relationship between the concentration ratio and the transmission loss. DETAILED DESCRIPTION

[0014] [Technical Problems to be Solved by the Present Disclosure]

[0015] Bromine and iodine have a higher rate of increase in refractive index per addition amount (mass %) than fluorine and chlorine. Therefore, it is possible to achieve glass materials with the same refractive index with a low concentration of addition, and it is easy to suppress the influence of other impurities generated in the addition process. On the other hand, due to the halogen molecules that are bonded to each other by the halogen elements, absorption losses may occur in the wavelength region of short wavelengths, namely ultraviolet and visible light. Therefore, the use of glass materials in the wavelength range of ultraviolet and visible light is limited.

[0016] For optical fibers, the edge of absorption loss caused by halogen molecules also affects the transmission band. In addition, if glass defects are generated due to the detachment of halogen ion bonds, the edge of glass defect absorption also affects the transmission band. As a result, there is a possibility that transmission loss will increase.

[0017] An object of the present disclosure is to provide a glass material and an optical fiber having low absorption in the ultraviolet and visible light wavelength regions.

[0018] [Effects of the present disclosure]

[0019] According to the present disclosure, it is possible to provide a glass material and an optical fiber having low absorption in the ultraviolet and visible light wavelength regions.

[0020] [Description of Embodiments of the Present Disclosure]

[0021] First, the embodiments of the present disclosure are described. (1) A glass material according to one embodiment of the present disclosure is a glass material composed of a silica-based glass and containing a halogen element, containing at least one of bromine and iodine, and a halogen molecule X2 and a halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥1. The glass material has little absorption in the wavelength region of ultraviolet light and visible light.

[0022] (2) In the above (1), the halogen molecule X2 and the halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥9. In this case, the absorption in the wavelength region of ultraviolet light and visible light is smaller.

[0023] (3) In (1) or (2), the relative refractive index difference based on the refractive index of silica glass may be -0.1% to 0.3%. When this glass material is used for core formation, excessive addition of down dopant to the cladding can be suppressed.

[0024] (4) The glass material of any one of (1) to (3) above may contain two or more halogen elements. In this case, it is possible to suppress the inclusion of a large amount of a specific halogen element. Therefore, it is possible to suppress the specific halogen element from reacting with other added elements to form impurities.

[0025] (5) The glass material of (4) may contain 50 ppm or more of two or more halogen elements, respectively, by mass fraction. In this case, it is possible to further suppress the reaction of a specific halogen element with other added elements to form an impurity.

[0026] (6) The glass material of (4) may contain 500 ppm or more of two or more halogen elements, respectively, by mass fraction. In this case, it is possible to further suppress the reaction of a specific halogen element with other added elements to form an impurity.

[0027] (7) The glass material according to any one of (1) to (6) may contain 90% by mass or more of silica glass. In this case, adverse effects on optical properties can be suppressed.

[0028] (8) An optical fiber according to one embodiment of the present disclosure comprises: a core composed of silica-based glass and containing a halogen element; and a cladding composed of silica-based glass and surrounding the core, wherein the core contains at least one of bromine and iodine, and in the core, the halogen molecules X2 and the halogen ions X - The concentration ratio satisfies [X - ] / [X2]≥1. This optical fiber has little absorption in the wavelength region of ultraviolet light and visible light.

[0029] [Details of the embodiments of the present disclosure]

[0030] Specific examples of the glass material and optical fiber disclosed in the present invention are described below with reference to the accompanying drawings. It should be noted that the present invention is not limited to these examples, and is represented by the claims, which are intended to include all changes within the meaning and scope equivalent to the claims. In the description of the drawings, the same elements are marked with the same reference numerals, and repeated descriptions are omitted.

[0031] (Glass material)

[0032] The glass material involved in this embodiment is, for example, optical glass. More specifically, the glass material is, for example, an optical fiber glass material used to form the core of an optical fiber. The glass material is composed of a silica-based glass containing silica glass as a main component. The glass material also contains other elements other than silicon (Si) and oxygen (O) constituting the silica glass.

[0033] The glass material contains a halogen element X. The halogen element X is any one of fluorine (F), chlorine (Cl), bromine (Br) and iodine (I). The glass material may contain a plurality of halogen elements. The glass material contains at least one of bromine and iodine.

[0034] The concentration of the halogen element X contained in the glass material can be above 50ppm, above 500ppm, or above 1000ppm in terms of mass ratio. As a result, the change in the viscosity of the glass caused by the change in the concentration of the added element becomes smaller, and the deviation of the optical properties of the glass becomes smaller. The concentration of the halogen element X contained in the glass material can be below 50000ppm in terms of mass ratio. As a result, the influence of the change in optical properties caused by large-scale addition can be suppressed, and a glass material with optical properties close to those of silica glass can be obtained. The above-mentioned concentration range is the same when the halogen element X is any of Cl, F, Br, and I. That is, when the glass material contains two or more halogen elements X, it is sufficient to control the concentration of each halogen element X within the above-mentioned range. Here, the mass ratio refers to the mass fraction.

[0035] The glass material may contain two or more halogen elements X, or three or more halogen elements X. If a specific halogen element X is added to the glass material in large quantities, the halogen element X may react with other added elements such as alkali metal elements and transfer to other substances and become impurities. If impurities are generated, it may affect the optical properties, especially increase the light absorption in the ultraviolet region. In the case where the glass material contains multiple halogen elements X, the concentration of each halogen element X required to achieve the desired refractive index can be reduced. In this way, impurity formation can be suppressed.

[0036] In optical fiber glass materials, if other material phases are generated during the fiberization process, the hardness of the glass becomes uneven, resulting in failure to achieve the target fiber diameter and refractive index curve. Therefore, in order to suppress the reduction in the yield of optical fiber, it is also important to suppress the concentration of each halogen element X.

[0037] The relative refractive index difference Δ of the glass material based on the refractive index of pure silica glass (SiO2, i.e., silica glass) can be greater than -0.1% and less than 0.3%, or greater than 0% and less than 0.3%, or greater than 0.1% and less than 0.3%. When such a glass material is used for core formation, it is possible to suppress excessive addition of down dopants such as F to the cladding. Therefore, it is possible to suppress the increase in transmission loss caused by an increase in the dopant concentration.

[0038] Alternatively, while the relative refractive index difference of the glass material is controlled within the above range, two or more halogen elements X among Cl, F, Br, and I are added in a mass ratio of 500 ppm or more. Alternatively, three or more halogen elements X are added in a mass ratio of 500 ppm or more. Here, the mass ratio refers to the mass fraction.

[0039] The glass material may also contain elements that easily become cations, such as alkali metal elements, alkaline earth metal elements, Group 13 elements, and Group 14 elements. Examples of alkali metal elements include lithium (Li), sodium (Na), and potassium (K). Examples of alkaline earth metal elements include magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). Examples of Group 13 elements include boron (B), aluminum (Al), gallium (Ga), and indium (In). Examples of Group 14 elements include germanium (Ge), tin (Sn), and lead (Pb).

[0040] By making the glass material contain cations, as described later, monovalent anions X of the halogen element X are easily generated. - . This makes it easy to suppress the generation of halogen molecules X2. On the other hand, if phase separation of the additives occurs due to the addition of multiple elements, it will have an adverse effect on the optical properties. Therefore, the proportion of silica glass as the main component can be 90% or more, 95% or more, or 98% or more by mass.

[0041] Halogen molecules X2 and halogen ions X - The concentration of I can be calculated using, for example, X-ray photoelectron spectroscopy (XPS). XPS can capture changes in the valence state of an element. For I, the I-derived ions can be observed between 618 eV and 620 eV. - The peaks of I2 can be observed between 620eV and 621eV. For Br, the peaks of Br can be observed between 70eV and 72eV. - A peak originating from Br2 can be observed between 68eV and 69eV.

[0042] These peaks are fitted with a Gaussian function, and the concentration ratio (molar ratio) is defined based on the area intensity ratio of the obtained fitting function. - The concentration ratio is independent of the element and satisfies [X - ] / [X2]≥1. The concentration ratio can satisfy [X - ] / [X2]≥9, and [X - ] / [X2]≥90, and [X -] / [X2]≥900. These concentration ratios will also affect the absorption in the ultraviolet region. - By adjusting the concentration ratio of halogen to halogen, a glass material with low absorption in a wide wavelength range can be manufactured. By using the glass material to form an optical fiber, the transmission loss of the optical fiber can be reduced. In addition, when the glass material contains two or more halogen elements, it is sufficient that at least one element satisfies the above concentration ratio.

[0043] The glass material is synthesized by a plasma melting method or the like. In order to suppress the generation of halogen molecules X2, it is also possible to generate halogen ions X - In order to generate the halide ion X - , the addition can also be carried out by applying high pressure.

[0044] (optical fiber)

[0045] Figure 1 : is a cross-sectional view showing an optical fiber according to an embodiment. The optical fiber 1 according to the embodiment includes a core 10 extending along a central axis 1a and a cladding 20 wrapping the core 10. The optical fiber 1 is formed using a glass material according to the embodiment. More specifically, the core 10 is formed using a glass material according to the embodiment. The cladding 20 is composed of a silica-based glass containing silica glass as a main component.

[0046] Table 1 shows the relationship between the concentration ratio and the transmission loss.

[0047] [Table 1

[0048]

[0049] Figures 2 to 5 It is a graph showing the relationship between the concentration ratio and the transmission loss. Figure 2 The case of chlorine is shown. Figure 3 The case of fluorine is shown. Figure 4 The case of bromine is shown. Figure 5 The situation of iodine is shown. As shown in Table 1 and Figures 2 to 5 As shown, it can be seen that the transmission loss tends to decrease as the concentration ratio increases. In the case of [X-] / [X2]≥1, it can be confirmed that the transmission loss is suppressed in any halogen element.

[0050] As mentioned above, although embodiment was demonstrated, this disclosure is not necessarily limited to the said embodiment and modification, Various changes are possible within the range which does not deviate from the summary.

[0051] Description of Reference Numerals

[0052] 1: optical fiber; 1a: central axis; 10: core; 20: cladding.

Claims

1. A glass material, which is a glass material composed of silica-based glass and contains a halogen element, contains at least one of bromine and iodine, Halogen molecule X2 and halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥1.

2. The glass material according to claim 1, wherein The halogen molecule X2 and the halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥9.

3. The glass material according to claim 1 or 2, wherein: The relative refractive index difference based on the refractive index of silica glass is not less than -0.1% and not more than 0.3%.

4. The glass material according to any one of claims 1 to 3, wherein Contains two or more of the halogen elements.

5. The glass material according to claim 4, wherein The two or more halogen elements are each contained at 50 ppm or more by mass fraction.

6. The glass material according to claim 4, wherein: The two or more halogen elements are each contained at 500 ppm or more by mass fraction.

7. The glass material according to any one of claims 1 to 6, wherein Contains 90% or more of silica glass by mass.

8. The glass material according to any one of claims 4 to 6, wherein The two or more halogen elements are each contained at a mass fraction of 50,000 ppm or more.

9. The glass material according to any one of claims 1 to 8, wherein It further contains at least any one of an alkali metal element, an alkaline earth metal element, a Group 13 element, and a Group 14 element.

10. The glass material according to any one of claims 1 to 9, wherein The relative refractive index difference based on the refractive index of silica glass is 0% or more and 0.3% or less.

11. The glass material according to any one of claims 1 to 10, wherein The relative refractive index difference based on the refractive index of silica glass is 0.1% or more and 0.3% or less.

12. The glass material according to any one of claims 1 to 11, wherein The halogen molecule X2 and the halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥90.

13. The glass material according to any one of claims 1 to 12, wherein: The halogen molecule X2 and the halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥900.

14. The glass material according to any one of claims 1 to 13, wherein The halogen element is any of fluorine, chlorine, bromine and iodine.

15. An optical fiber comprising: A core composed of silica-based glass containing a halogen element; and A cladding layer, composed of silica-based glass, surrounds the core, The core contains at least one of bromine and iodine, In the core, the halogen molecule X2 and the halogen ion X - The concentration ratio satisfies [X - ] / [X2]≥1.

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