Glass material and optical fiber

Abstract

The glass material is composed of silica-based glass, contains a group 14 element, and contains tetravalent ions (X4 +) and divalent ions (X2 +) of element (X), which are at least one of tin and lead.

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. 2022-094170 filed on June 10, 2022, and all the contents described in the Japanese Application are incorporated herein by reference. Background Art

[0002] Germanium can be used as an up-dopant for increasing the refractive index of glass. Non-Patent Document 1 discloses an optical fiber in which germanium is doped in the core.

[0003] Prior art literature

[0004] Non-patent literature

[0005] Non-patent document 1: Nakahara Kihiro, and two others, "Lower loss of optical fiber", Applied Physics, Vol. 50, No. 10 (1981), pp. 1006-1020 Summary of the invention

[0006] A glass material according to one embodiment of the present disclosure is a glass material composed of silica-based glass and containing a Group 14 element, and contains a tetravalent ion X of at least one element X of tin and lead. 4+ and the divalent ion X of element X 2+ .

[0007] An optical fiber according to one embodiment of the present disclosure comprises: a core composed of silica-based glass and containing a Group 14 element; and a cladding composed of silica-based glass and surrounding the core, wherein the core contains a tetravalent ion X of an element X of at least one of tin and lead. 4+ and the divalent ion X of element X 2+ . BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a cross-sectional view showing an optical fiber according to an embodiment.

[0009] Figure 2 It is a graph showing the relationship between the concentration ratio and the transmission loss.

[0010] Figure 3 It is a graph showing the relationship between the concentration ratio and the transmission loss. DETAILED DESCRIPTION

[0011] [Technical Problems to be Solved by the Present Disclosure]

[0012] In non-patent document 1, it is recorded that Rayleigh scattering caused by composition fluctuation increases in proportion to the dopant concentration. In addition, if the dopant concentration increases, the following problems may occur. That is, the probability of impurities that may be contained in the dopant increases, and absorption in the ultraviolet / visible light region caused by impurities may occur. In addition, the probability of the added element (dopant) deforming the network structure of silica glass increases, resulting in glass defects, as a result, it is possible to increase the absorption in the ultraviolet wavelength region. In this field, it is desired to have a glass material and an optical fiber with high transmittance in a wide wavelength region.

[0013] An object of the present disclosure is to provide a glass material and an optical fiber having high transmittance in a wide wavelength range.

[0014] [Effects of the present disclosure]

[0015] According to the present disclosure, it is possible to provide a glass material and an optical fiber having high transmittance in a wide wavelength range.

[0016] [Description of Embodiments of the Present Disclosure]

[0017] 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 Group 14 element, and contains a tetravalent ion X of at least one element X of tin and lead. 4+ and the divalent ion X of element X 2+ This glass material can achieve high transmittance in a wide wavelength range.

[0018] (2) In the above (1), the tetravalent ion X 4+ With divalent ion X 2+ The concentration ratio satisfies [X 4+ ] / [X 2+ ]≥1. In this case, higher transmittance can be achieved in a wide wavelength region.

[0019] (3) In the above (1), the tetravalent ion X 4+ With divalent ion X 2+ The concentration ratio satisfies [X 4+ ] / [X 2+ ] ≥ 10. In this case, particularly high transmittance can be achieved in a wide wavelength region.

[0020] (4) In any one of (1) to (3), the relative refractive index difference based on the refractive index of silica glass may be 0% or more. When this glass material is used for core formation, excessive addition of down dopant to the cladding can be suppressed.

[0021] (5) The glass material of any one of (1) to (4) may contain two or more elements of Group 14. In this case, it is possible to suppress the inclusion of a large amount of a specific Group 14 element. Therefore, it is possible to suppress the phase separation of the substance into two components that occurs with an increase in concentration.

[0022] (6) The glass material according to any one of (1) to (5) may contain 90% by mass or more of silica glass. In this case, adverse effects on optical properties can be suppressed.

[0023] (7) An optical fiber according to one embodiment of the present disclosure comprises: a core composed of silica-based glass and containing a Group 14 element; and a cladding composed of silica-based glass and surrounding the core, wherein the core contains a tetravalent ion X of an element X of at least one of tin and lead. 4+ and the divalent ion X of element X 2+ Since this optical fiber can achieve high transmittance in a wide wavelength range, the loss in the transmission band is reduced.

[0024] [Details of the embodiments of the present disclosure]

[0025] 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.

[0026] (Glass material)

[0027] The glass material involved in this embodiment is, for example, an optical glass material. More specifically, the glass material is, for example, an optical fiber glass material, which is used to form the core of the 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.

[0028] The glass material contains a Group 14 element. Examples of Group 14 elements include germanium (Ge), tin (Sn), and Pb (lead). The glass material may contain a plurality of Group 14 elements. The glass material contains a tetravalent ion X of at least one of the elements X of tin and lead. 4+ and the divalent ion X 2+ The glass material may contain Group 14 elements other than tin and lead.

[0029] Compared with germanium, tin and lead can change the refractive index difference of glass materials at low concentrations. Therefore, it is easy to make high-refractive-index glass by using tin and lead, and as a result, it can be applied to optical glass materials for a wide range of purposes. In particular, when used in optical fibers, it is possible to suppress the loss caused by the increase in the addition concentration.

[0030] The valence of tin and lead tends to change easily. If the valence is different, the absorption band from the added element will be different. The tetravalent ion X of the element X of at least one of tin and lead 4+ The absorption bands of divalent ions X 2+ The absorption bands of ions are all present in the UV / visible region. 4+ The absorption band of the divalent ion X 2+ Compared with the absorption band of the ion X, the peak of the ion X tends to shift toward the shorter wavelength side, that is, away from the near-infrared side of the transmission band. 4+ With divalent ion X 2+ Compared with the tetravalent ion Si 4+ The deformation at the atomic level can be suppressed during the replacement, and as a result, the generation of glass defects can be suppressed.

[0031] A tetravalent ion X of an element X of at least one of tin and lead 4+ With divalent ion X 2+ The concentration ratio can satisfy [X 4+ ] / [X 2+ ]≥1, and can also satisfy [X 4+ ] / [X 2+ ]≥10, and can also satisfy [X 4+ ] / [X 2+ ]≥100. That is, in the case of lead, [Pb 4+ ] / [Pb 2+ ] may be greater than 1, greater than 10, or greater than 100. In the case of tin, [Sn 4 + ] / [Sn 2+ ] can be greater than 1, greater than 10, or greater than 100.

[0032] The glass material may contain two or more Group 14 elements, or may contain three or more Group 14 elements. When the glass material contains multiple Group 14 elements, the concentration of each Group 14 element required to achieve the desired refractive index can be reduced. Therefore, it is possible to suppress the state in which the compound of the Group 14 element and the element present in the glass is phase-separated into two components as the concentration increases. In addition, when the glass material contains two or more Group 14 elements, it is sufficient that at least one element satisfies the above-mentioned concentration ratio.

[0033] If such a phase separation state occurs, light absorption / scattering occurs at the phase interface, resulting in changes in optical properties. These phase states will also change greatly when the cooling rate of the glass manufacturing process, such as a subtle temperature difference of about 10°C, occurs. Therefore, the controllability of the optical properties is greatly deteriorated. Therefore, it is very important to suppress phase separation. In the case of glass materials for optical fibers, if other material phases are produced during the fiberization process, the hardness in the glass becomes uneven, resulting in the inability to achieve the target fiber diameter and refractive index curve. Therefore, in order to suppress the reduction in the yield of optical fibers, it is also important to suppress the concentration of each Group 14 element.

[0034] The concentration of the Group 14 element contained in the glass material is set according to the refractive index of the target glass material. The change in the refractive index difference of the glass material based on the refractive index of pure silica glass (SiO2, i.e., silica glass) is 0.06% per 1 mass % in the case of germanium, 0.14% per 1 mass % in the case of tin, and 0.12% per 1 mass % in the case of lead.

[0035] 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 0% or more, 0.2% or more, or 0.3% or more. 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 increased addition concentration. The relative refractive index difference Δ can be greater than 0%.

[0036] If a single element is added, that is, only one Group 14 element is added, in the case of germanium, the mass ratio may be 50 ppm or more, 30,000 ppm or more, or 50,000 ppm or more. In the case of tin and lead, the mass ratio may be 50 ppm or more, 14,000 ppm or more, or 20,000 ppm or more.

[0037] The glass material may also contain alkali metal elements, alkaline earth metal elements, Group 13 elements, and halogen elements. Examples of alkali metal elements include lithium (Li), sodium (Na), potassium (K), and rubidium (Rb). 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 halogen elements include fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).

[0038] In particular, halogen elements are easy to oxidize other elements, so it is easy to make the 14th group element into a tetravalent ion. On the other hand, if phase separation of the additive substances 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 ratio.

[0039] The evaluation of the valence of lead and tin is performed, for example, using X-ray photoelectron spectroscopy (XPS). 2+ The peak originating from Pb can be observed between 138eV and 139eV. 4+ For tin, the peak from Sn can be observed between 486eV and 487eV. 2+ The peak originating from Sn can be observed between 487eV and 488eV. 4+ The peaks are fitted using a Gaussian function to identify the peaks. The concentration ratio is defined based on the area intensity ratio of the fitted function.

[0040] The glass material is made by plasma sintering or the like. In the plasma sintering method, addition and sintering are performed in a nitrogen and oxygen (N2+O2) atmosphere. Depending on the atmosphere during sintering, the valence of the added tin and lead can be easily controlled. 4+ When element X is added in a state, the gas partial pressure ratio of oxygen and non-oxygen can be [oxygen] / [non-oxygen]≥3, [oxygen] / [non-oxygen]≥5, or [oxygen] / [non-oxygen]≥10.

[0041] (optical fiber)

[0042] 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.

[0043] Table 1 shows the relationship between the concentration ratio and the transmission loss.

[0044] [Table 1]

[0045]

[0046] Figure 2 as well as Figure 3 It is a graph showing the relationship between the concentration ratio and the transmission loss. Figure 2 The case of lead is shown. Figure 3The situation of tin is shown in Table 1. Figure 2 as well as Figure 3 As shown in Figure 2, it can be seen that as the concentration ratio increases, the transmission loss tends to decrease. 4+ ] / [X 2+ ]≥1, it can be confirmed that the transmission loss in both the case of lead and tin is suppressed.

[0047] 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.

[0048] Description of Reference Numerals

[0049] 1: optical fiber; 1a: central axis; 10: core; 20: cladding.

Claims

1. A glass material comprising a silica-based glass and containing a Group 14 element, A tetravalent ion X containing an element X of at least one of tin and lead 4+ and the divalent ion X of the element X 2+ .

2. The glass material according to claim 1, wherein The 4-valent ion X 4+ With the divalent ion X 2+ The concentration ratio satisfies [X 4+ ] / [X 2+ ]≥1.

3. The glass material according to claim 1 or 2, wherein: The 4-valent ion X 4+ With the divalent ion X 2+ The concentration ratio satisfies [X 4+ ] / [X 2+ ]≥10.

4. The glass material according to any one of claims 1 to 3, wherein The relative refractive index difference based on the refractive index of silica glass is 0% or more.

5. The glass material according to any one of claims 1 to 4, wherein Contains two or more Group 14 elements.

6. The glass material according to any one of claims 1 to 5, wherein Contains 90% or more of silica glass by mass.

7. The glass material according to any one of claims 1 to 6, wherein The 4-valent ion X 4+ With the divalent ion X 2+ The concentration ratio satisfies [X 4+ ] / [X 2+ ]≥100.

8. The glass material according to any one of claims 1 to 7, wherein The relative refractive index difference based on the refractive index of silica glass is 0.2% or more.

9. The glass material according to any one of claims 1 to 8, wherein The relative refractive index difference based on the refractive index of silica glass is 0.3% or more.

10. The glass material according to any one of claims 1 to 9, wherein Contains 95% or more of silica glass by mass.

11. The glass material according to any one of claims 1 to 10, wherein Contains 98% or more of silica glass by mass.

12. An optical fiber comprising: a core composed of silica-based glass containing one or more elements selected from the group consisting of germanium, tin and lead; and A cladding layer, composed of silica-based glass, surrounds the core, The core contains a tetravalent ion X of an element X of at least one of tin and lead. 4+ and the divalent ion X of the element X 2+ .

Images