Method for manufacturing glass material

Abstract

To provide a method for manufacturing a glass material that indicates a high-light transmittance in a use wave length.SOLUTION: A method for manufacturing a glass material includes a melting step of melting and solidifying a glass raw material containing a reductant, where a glass material is a paramagnetic glass material.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a glass material.

Background Art

[0002] Paramagnetic glass materials are known to exhibit the Faraday effect, which is one of the magneto-optical effects. The Faraday effect is an effect that rotates linearly polarized light passing through a material placed in a magnetic field. Magneto-optical elements (for example, Faraday rotators) utilizing this effect are used in magneto-optical devices such as optical isolators.

[0003] The angle of rotation of polarization (the rotation angle of the plane of polarization) θ due to the Faraday effect is represented by the following formula. Here, H is the strength of the magnetic field, L is the length of the material through which the polarized light passes, and V is a constant (Verdet constant) depending on the type of the material. The larger the absolute value of the Verdet constant, the larger the absolute value of the angle of rotation of polarization, and as a result, a larger Faraday effect is exhibited.

[0004] θ = VHL

[0005] As glass materials exhibiting the Faraday effect, for example, SiO2 - B2O3 - Al2O3 - Tb2O3 systems (Patent Document 1) and P2O5 - B2O3 - Tb2O3 systems (Patent Document 2) are known.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In recent years, due to the increase in the output power of the laser light irradiated on magneto-optical devices, improvement in the light transmittance of magneto-optical elements at the operating wavelength (e.g., 300 to 1100 nm) has been demanded.

[0008] In view of the above, an object of the present invention is to provide a method for manufacturing a glass material that exhibits high light transmittance at the operating wavelength.

Means for Solving the Problems

[0009] The method for manufacturing a glass material of the present invention is characterized in that the glass material is a paramagnetic glass material and includes a melting step of melting and solidifying a glass raw material containing a reducing agent.

[0010] The method for manufacturing a glass material of the present invention preferably further includes a remelting step.

[0011] In the method for manufacturing a glass material of the present invention, the reducing agent is preferably carbon.

[0012] In the method for manufacturing a glass material of the present invention, the content of the reducing agent in the glass raw material is preferably 0.001% to 1% by mass on an external basis.

[0013] In the melting step of the method for manufacturing a glass material of the present invention, the melting time is preferably 3 hours or less.

[0014] In the remelting step of the method for manufacturing a glass material of the present invention, the melting time is preferably 4 hours or more.

[0015] In the method for manufacturing a glass material of the present invention, the melting atmosphere in the remelting step is preferably a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere.

[0016] In the method for manufacturing a glass material of the present invention, the glass material is preferably a Tb2O3-based glass material.

[0017] In the method for manufacturing the glass material of the present invention, the Tb2O3-based glass material preferably contains 25% or more of Tb2O3 in mol%.

[0018] In the method for manufacturing the glass material of the present invention, the Tb2O3-based glass material preferably contains, in mol%, 26% to 40% of Tb2O3, more than 12% to 40% of B2O3, 1% to 20% of Al2O3, 1% to 40% of SiO2, 0% to 5% of P2O5, and more than 14% to 74% of B2O3 + Al2O3 + SiO2 + P2O5.

[0019] In the method for manufacturing the glass material of the present invention, the glass material preferably has a light transmittance of 70% or more at a wavelength of 532 nm.

Effect of the Invention

[0020] According to the present invention, it is possible to provide a method for manufacturing a glass material that exhibits high light transmittance at the wavelength of use.

Embodiment for Carrying Out the Invention

[0021] The present invention is a method for manufacturing a glass material, characterized in that the glass material is a paramagnetic glass material and includes a melting step of melting a glass raw material containing a reducing agent. According to the present invention, it is possible to manufacture a glass material that exhibits high light transmittance at the wavelength of use. Further, in the present invention, in a glass material whose characteristics are likely to change due to a change in the valence of the constituent components, for example, in a paramagnetic glass material, it becomes easier to manufacture a glass material that exhibits high light transmittance at the wavelength of use.

[0022] (Melting Step) First, a glass raw material containing a reducing agent is melted and solidified (melting step). By including a reducing agent in the glass raw material, it becomes easier to suppress the coloring of the glass material and easier to suppress a decrease in the light transmittance of the glass material. For example, when the glass material is a Tb2O3-based glass material which is a kind of paramagnetic glass material, by including a reducing agent, Tb which is the cause of coloring 4+ can be reduced to Tb 3+ , and it becomes easier to suppress a decrease in the light transmittance of the glass material.

[0023] The reducing agent is preferably carbon. For example, carbon is preferably used in powder form. Thereby, carbon can be uniformly distributed in the glass raw material. Note that the reducing agent is not limited to carbon, and for example, wood powder, metallic aluminum, metallic silicon, aluminum fluoride, ammonium salts, etc. may be used.

[0024] The content of the reducing agent in the glass raw material is preferably 0.001% to 1%, 0.01% to 1%, 0.05% to 0.9%, 0.1% to 0.8%, particularly 0.1% to 0.7% by external percentage mass. If the reducing agent is too little, it becomes difficult to obtain a reduction effect, and it becomes difficult to suppress the coloring of the glass material. If the reducing agent is too much, the molten glass is excessively reduced, and conversely, the glass material becomes liable to be colored. For example, when melting the glass raw material using a platinum crucible, if the reducing agent is too much, fine Pt particles are generated in the molten glass, and the light transmittance of the glass material is liable to decrease. Note that the content of the reducing agent means the value added by external percentage to the glass raw material.

[0025] The melting step is preferably carried out in an air atmosphere. Thereby, it becomes easy to reduce the manufacturing cost. Note that the melting step may be carried out in a vacuum atmosphere, an inert atmosphere or a reducing atmosphere.

[0026] In the melting step, the melting time is preferably 3 hours or less, 2 hours or less, particularly 1 hour or less. Also, the melting time is preferably 5 minutes or more, 10 minutes or more, particularly 20 minutes or more. If the melting time is too short, the melting of the glass raw material becomes insufficient, and it becomes difficult to obtain a glass material with a uniform composition. If the melting time is too long, the constituent components of the melting container are liable to dissolve into the molten glass. For example, when melting the glass raw material using a platinum crucible, if the melting time is too long, fine Pt particles are generated in the molten glass, and the light transmittance of the glass material is liable to decrease. Also, when melting the glass raw material using a quartz crucible, if the melting time is too long, SiO2 dissolves into the molten glass, and it becomes difficult to obtain a glass material having a desired composition.

[0027] In the melting process, it is preferable that the surface of the melting vessel in contact with the molten glass is made of quartz, platinum, or a platinum alloy. For example, a quartz crucible, a platinum crucible, a platinum-rhodium crucible, a reinforced platinum crucible, a melting furnace lined with platinum or a platinum alloy, etc. can be used as the melting vessel.

[0028] By solidifying the molten glass by a desired cooling method, a glass material can be obtained. The cooling method is not particularly limited, and for example, water cooling or roller quenching can be performed. By these methods, a glass material in the form of fragments or flakes can be obtained. By using a glass material of these shapes, it becomes easier to remelt the glass material in the remelting process described later.

[0029] (Remelting process) The glass material is preferably remelted (remelting process). Thereby, sufficient clarification of the molten glass can be performed, and it becomes easier to obtain a glass material with few residual bubbles. If residual bubbles exist in the glass material, light scattering occurs, and the light transmittance of the glass material tends to decrease. In the present invention, the glass before being remelted may be referred to as a precursor glass material for convenience.

[0030] In the remelting process, it is preferable that the melting time is 4 hours or more, 5 hours or more, particularly 6 hours or more. Also, the melting time is preferably 10 hours or less, 9 hours or less, particularly 8 hours or less. If the melting time is too short, the clarification of the molten glass becomes insufficient, and residual bubbles tend to increase. If the melting time is too long, the constituent components of the melting vessel tend to dissolve into the molten glass. For example, when remelting a glass material using a platinum crucible, if the melting time is too long, fine Pt particles are generated in the molten glass, and the light transmittance of the glass material tends to decrease. Also, when remelting a glass material using a quartz crucible, if the melting time is too long, SiO2 dissolves into the molten glass, and it becomes difficult to obtain a glass material having a desired composition.

[0031] In the remelting process, it is preferable that the surface of the melting vessel in contact with the molten glass is made of platinum or a platinum alloy. For example, it is preferable to use a platinum crucible, a platinum-rhodium crucible, a strengthened platinum crucible, a melting furnace lined with platinum or a platinum alloy, etc. as the melting vessel. Note that a quartz crucible may be used as the melting vessel.

[0032] The obtained glass material is preferably annealed. Thereby, the strain of the glass material can be removed. Note that annealing may be performed in any of an air atmosphere, a reducing atmosphere, and an inert atmosphere, but from the viewpoint of reducing the manufacturing cost, it is preferable to perform annealing in an air atmosphere.

[0033] The melting atmosphere in the remelting process is preferably a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere. Thereby, oxidation of the molten glass is suppressed, and it becomes easier to further suppress coloring of the glass material.

[0034] The method for manufacturing the glass material of the present invention can be used, for example, when manufacturing a paramagnetic glass material. When oxidation occurs during the production of a paramagnetic glass material, the valence of the constituent components changes, and the characteristics (for example, light transmittance) are likely to change. Therefore, by using the manufacturing method of the present invention, oxidation of the paramagnetic glass material is suppressed, and it becomes easier to suppress characteristic changes. Examples of the paramagnetic glass material include Tb2O3-based glass materials, Pr2O3-based glass materials, and EuO-based glass materials.

[0035] The Tb2O3-based glass material preferably contains 25% or more of Tb2O3 in mol%. For example, a glass material containing 26% to 40% of Tb2O3, more than 12% to 40% of B2O3, 1% to 20% of Al2O3, 1% to 40% of SiO2, 0% to 5% of P2O5, and more than 14% to 74% of B2O3 + Al2O3 + SiO2 + P2O5 in mol% is preferable. A glass material satisfying the above composition is likely to exhibit high light transmittance at the wavelength of use. The reasons for defining the glass composition and the content of each component will be described below. In the following description, unless otherwise specified, “%” means “mol%”.

[0036] Tb2O3 is a component that increases the Faraday effect by increasing the absolute value of the Verdet constant. The content of Tb2O3 is preferably 26% - 40%, 26% - 39%, 26% - 36%, 26% - 35%, 28% - 35%, 29% - 35%, 30% - 34%, particularly 31% - 34%. If the content of Tb2O3 is too low, it is difficult to obtain the above effect. If the content of Tb2O3 is too high, it is difficult to vitrify. Note that Tb exists in the glass in a trivalent or tetravalent state, but in the present invention, all of these are represented as Tb2O3.

[0037] The ratio of Tb to total Tb 3+ is preferably 55% or more, 60% or more, 70% or more, 80% or more, particularly 90% or more in mol%. Thereby, the ratio of Tb 4+ which is the cause of the coloring of the glass material decreases, and it becomes easier to suppress the decrease in the light transmittance of the glass material. Note that Tb 4+ has absorption in the wavelength range of 300 - 1100 nm. If the ratio of Tb 3+ to total Tb is too small, the glass material will be colored, the light transmittance in the above wavelength range will decrease, and the glass material will easily generate heat. This heat generation causes a thermal lens effect, so when the glass material is irradiated with laser light, the beam profile of the laser light is likely to be deformed.

[0038] The ratio of Tb to total Tb 3+ can be increased by reducing the Tb 4+ present in the glass material to Tb 3+ . As described above, in the present invention, a glass material is produced by melting a glass raw material containing a reducing agent. Therefore, according to the manufacturing method of the present invention, it is easy to reduce Tb 4+ to Tb 3+ , and it becomes easy to increase the ratio of Tb 3+ to total Tb.

[0039] B2O3 is a component that expands the vitrification range and stabilizes vitrification. The content of B2O3 is preferably more than 12% to 40%, 15% to 38%, 16% to 36%, 20% to 35%, 21% to 35%, 21% to 32%, more than 25% to 32%, particularly 26% to 32%. If the content of B2O3 is too low, it becomes difficult to vitrify. If the content of B2O3 is too high, it becomes difficult to obtain a sufficient Faraday effect. Also, the thermal stability and the hardness of the glass tend to decrease.

[0040] Al2O3 is a component that forms the glass skeleton and expands the vitrification range. The content of Al2O3 is preferably 1% to 20%, 2% to 20%, 3% to 20%, 5% to 20%, 7% to 20%, 10% to 20%, particularly 11% to 19%. If the content of Al2O3 is too low, it is difficult to obtain the above effects. If the content of Al2O3 is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0041] SiO2 becomes the glass skeleton and is a component that expands the vitrification range. The content of SiO2 is preferably 1% to 40%, 5% to 40%, 10% to 38%, 15% to 35%, 18% to 32%, 20% to 32%. If the content of SiO2 is too low, it is difficult to obtain the above effects. If the content of SiO2 is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0042] P2O5 becomes the glass skeleton and is a component that expands the vitrification range. The content of P2O5 is preferably 0% to 5%, less than 0% to 5%, 0% to 4%, 0.1% to 4%, particularly 1% to 4%. If the content of P2O5 is too high, it becomes difficult to obtain a sufficient Faraday effect. Also, the thermal stability and the hardness tend to decrease.

[0043] The content of B2O3+Al2O3+SiO2+P2O5 (the total content of B2O3, Al2O3, SiO2, and P2O5) is preferably more than 14% to 74%, 20% to 74%, 30% to 74%, 40% to 74%, 50% to 72%, 55% to 71%, 60% to 70%, particularly 60% to 69%. If the content of B2O3+Al2O3+SiO2+P2O5 is too low, it becomes difficult to vitrify. If the content of B2O3+Al2O3+SiO2+P2O5 is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0044] In addition to the above components, the following components can be contained in the above-mentioned Tb2O3-based glass material.

[0045] La2O3, Gd2O3, Y2O3, and Yb2O3 are components that stabilize vitrification. The content of La2O3, Gd2O3, Y2O3, and Yb2O3 is preferably 10% or less, 7% or less, 5% or less, 4% or less, 2% or less, particularly 1% or less, respectively. If the content of these components is too high, conversely, it becomes difficult to vitrify.

[0046] Dy2O3, Eu2O3, and Ce2O3 are also components that contribute to the improvement of the Verdet constant. The content of Dy2O3, Eu2O3, and Ce2O3 is preferably 1% or less, 0.5% or less, 0.1% or less, particularly 0.01% or less, respectively. If the content of these components is too high, the light transmittance at wavelengths of 300 to 1100 nm decreases, and the glass material tends to generate heat. This heat generation can cause deformation of the laser beam profile due to the thermal lens effect caused by the heat generation. Note that Dy, Eu, and Ce present in the glass exist in a trivalent or tetravalent state, but in the present invention, all of these are represented as Dy2O3, Eu2O3, and Ce2O3, respectively.

[0047] Pr2O3 is a component that contributes to the improvement of the Verdet constant. The content of Pr2O3 is preferably 5% or less, 3% or less, less than 1%, particularly 0.5% or less. If the content of Pr2O3 is too high, it becomes difficult to vitrify.

[0048] MgO, CaO, SrO, and BaO are components that stabilize vitrification and enhance chemical durability. The content of MgO, CaO, SrO, and BaO is preferably 0% - 10%, particularly 0% - 5% respectively. If the content of these components is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0049] GeO2 is a component that enhances glass - forming ability. The content of GeO2 is preferably 0% - 15%, 0% - 10%, 0% - 9%, 0% - 7%, 0% - 5%, particularly 0% - 4%. If the content of GeO2 is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0050] Ga2O3 is a component that enhances glass - forming ability and broadens the vitrification range. The content of Ga2O3 is preferably 0% - 6%, 0% - 5%, 0% - 4%, particularly 0% - 2%. If the content of Ga2O3 is too high, it is more likely to devitrify. Also, it becomes difficult to obtain a sufficient Faraday effect.

[0051] Fluorine has the effect of enhancing glass - forming ability and broadening the vitrification range. The content of fluorine (in terms of F2 conversion) is preferably 0% - 10%, 0% - 7%, 0% - 5%, 0% - 3%, 0% - 2%, particularly 0% - 1%. If the content of fluorine is too high, there is a risk that components will volatilize during melting, which may adversely affect vitrification. Also, veining is likely to occur.

[0052] For the glass material, the content of FeO and Fe2O3 is preferably 10 ppm or less, 7 ppm or less, 5 ppm or less, 4 ppm or less, 2 ppm or less, 1 ppm or less, particularly 0.8 ppm or less respectively. FeO shows broad absorption peaks around a wavelength of 1200 nm due to Fe 2+ resulting in a decrease in light transmittance in the wavelength range of 800 - 1200 nm, making the glass material prone to heat generation. This heat generation causes a thermal lens effect and can be the cause of laser beam profile deformation. Also, Fe2O3 is reduced to FeO during the melting process, and similarly, Fe 2+There is a risk of causing broad absorption. Therefore, if the content of FeO + Fe2O3 is too high, a thermal lens effect will occur, and the beam profile of the laser light is likely to be deformed. The lower limit of the content of FeO + Fe2O3 is not particularly limited, but for example, it is 0.01 ppm or more. In addition, the content of each of FeO and Fe2O3 is preferably 10 ppm or less, 7 ppm or less, 5 ppm or less, 4 ppm or less, 2 ppm or less, 1 ppm or less, and particularly preferably 0.8 ppm or less.

[0053] The glass material preferably does not substantially contain Sb2O3 and As2O3. When these components are contained, bubbles are likely to remain in the glass material, and the light transmittance of the glass material is likely to decrease. The above "does not substantially contain" means that it is not intentionally contained in the glass raw material, and does not exclude the mixing of impurity levels. Objectively, the content of each component refers to less than 1000 ppm.

[0054] The glass material preferably has a light transmittance of 70% or more, 72% or more, 75% or more, and particularly preferably 80% or more at a wavelength of 532 nm. Also, at a wavelength of 633 nm, the light transmittance is preferably 70% or more, 75% or more, and particularly preferably 80% or more. Further, at a wavelength of 1064 nm, the light transmittance is preferably 80% or more, 82% or more, and particularly preferably 85% or more. The above light transmittance is the value when the thickness of the glass material is 1 mm.

[0055] Thus, according to the manufacturing method of the present invention, it is easy to suppress the coloring of the glass material. Thereby, a glass material showing a high light transmittance at the wavelength used can be manufactured. For example, when the glass material is a Tb2O3-based glass material, reducing Tb 4+ to Tb 3+ can increase the ratio of Tb 3+ to the total Tb, and the coloring of the glass material can be suppressed.

Examples

[0056] Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

[0057] Tables 1 to 3 show Examples 1 to 12, 14 to 17 and Comparative Example 13 of the present invention.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] Examples 1 to 10, 14 to 17 were prepared as follows. First, raw materials were formulated to obtain the glass compositions shown in Tables 1 to 3, and 300 g of glass raw materials were obtained. Further, 0.5% of carbon was added to the glass raw materials by weight of external cutting. The glass raw materials after carbon addition were put into a quartz crucible and melted under the conditions described in Tables 1 to 3. After melting, the molten glass was water-cooled and solidified in an air atmosphere to obtain a precursor glass material. The precursor glass material thus obtained was in the form of fragments.

[0062] Next, 100 g of the precursor glass material was put into a platinum crucible and remelted under the conditions described in Tables 1 to 3. After remelting, the molten glass was poured out onto a carbon plate in an air atmosphere to obtain a glass material. The obtained glass material was annealed at 770 °C for 1 hour in an air atmosphere.

[0063] After obtaining a glass material in the same procedure as in Examples 1 to 10, 14 to 17, the glass material without performing the remelting step was designated as Example 11.

[0064] Example 12 was prepared as follows. First, a glass raw material was prepared in the same procedure as in Examples 1 to 10, and 0.5% of carbon was added to the glass raw material in terms of the weight percentage of external cutting. The glass raw material after the addition of carbon was put into a platinum crucible and melted at 1400 °C for 6 hours in an inert atmosphere (nitrogen atmosphere). After melting, the molten glass was poured onto a carbon plate in an air atmosphere to obtain a glass material. The obtained glass material was annealed at 770 °C for 1 hour in an air atmosphere. Note that Example 12, like Example 11, did not perform a remelting process.

[0065] Comparative Example 13 was prepared as follows. First, a precursor glass material was obtained in the same procedure as in Examples 1 to 10 except that carbon was not added to the glass raw material. Next, the precursor glass material was remelted at 1400 °C for 5 hours in an air atmosphere. After remelting, the molten glass was poured onto a carbon plate in an air atmosphere to obtain a glass material. The obtained glass material was annealed at 770 °C for 1 hour in an air atmosphere.

[0066] For the obtained glass material, the Verdet constant, light transmittance, ratio of Tb to total Tb 3+ were measured respectively for residual bubbles and glass coloring. The results are shown in Tables 1 to 3.

[0067] The Verdet constant was measured using the rotating analyzer method. Specifically, the obtained glass material was polished to a thickness of 1 mm, and the Faraday rotation angle in the wavelength range of 400 nm to 1100 nm was measured in a magnetic field of 10 kOe, and the Verdet constant at a wavelength of 532 nm was calculated.

[0068] The light transmittance was measured using a spectrophotometer (V-670 manufactured by JASCO Corporation). Specifically, the obtained glass material was polished to a thickness of 1 mm, and the light transmittance at a wavelength of 532 nm was read from the light transmittance curve. Note that the light transmittance is the external transmittance including reflection.

[0069] Tb with respect to total Tb 3+The ratio was measured using X-ray absorption fine structure analysis (XAFS). Specifically, a spectrum of the X-ray absorption edge structure region (XANES) was obtained, and the ratio (mol%) of Tb 3+ to the total Tb was calculated from the shift amount of the peak position of each Tb ion.

[0070] Residual bubbles were evaluated by the number of bubbles that could be confirmed when visually observing a 1 cm 3 glass material. Samples with 9 or fewer visible bubbles were marked as ○, and those with 10 or more were marked as ×.

[0071] The coloring of the glass material was evaluated by visually checking the glass material. Samples with the original color of the glass material were marked as ○, and samples with coloring were recorded for the specific coloring state.

[0072] As shown in Tables 1 to 3, the glass materials of Examples 1 to 12, 14 to 17 had an absolute value of the Verdet constant of 0.511 to 0.799 min / Oe·cm at a wavelength of 532 nm. Also, all had a light transmittance of 70% or more at a wavelength of 532 nm, showing good light transmittance. On the other hand, as shown in Table 2, Comparative Example 13 had a low light transmittance at a wavelength of 532 nm.

Industrial Applicability

[0073] The glass material produced by the manufacturing method of the present invention can be suitably used for magneto-optical elements (for example, Faraday rotors) that constitute magnetic devices such as optical isolators, optical circulators, and magnetic sensors.

Claims

**Claim 1** A method for manufacturing a glass material in which a molten container comes into contact with molten glass, comprising: The glass material is a Tb₂O₃-based glass material, and in mol%, it contains 26% to 40% of Tb₂O₃, more than 12% to 40% of B₂O₃, 1% to 20% of Al₂O₃, 1% to 40% of SiO₂, 0.1% to 5% of P₂O₅, 0% to 4% of Ga₂O₃, and more than 14% to 74% of B₂O₃ + Al₂O₃ + SiO₂ + P₂O₅. A method for manufacturing a glass material, comprising a melting step of melting and solidifying a glass raw material containing a reducing agent. **Claim 2** The method for manufacturing a glass material according to claim 1, further comprising a remelting step. **Claim 3** The method for manufacturing a glass material according to claim 1 or 2, wherein the reducing agent is carbon. **Claim 4** The method for manufacturing a glass material according to any one of claims 1 to 3, wherein the content of the reducing agent in the glass raw material is 0.001% to 1% by weight on an external basis. **Claim 5** The method for manufacturing a glass material according to any one of claims 1 to 4, wherein in the melting step, the melting time is 3 hours or less. **Claim 6** The method for manufacturing a glass material according to claim 2, wherein in the remelting step, the melting time is 4 hours or more. **Claim 7** The method for manufacturing a glass material according to claim 2, wherein the melting atmosphere in the remelting step is a vacuum atmosphere, an inert atmosphere, or a reducing atmosphere. **Claim 8** The method for manufacturing a glass material according to any one of claims 1 to 7, wherein the ratio of Tb³⁺ to the total Tb in the Tb₂O₃-based glass material is 55% or more in mol%. **Claim 9** The method for manufacturing a glass material according to any one of claims 1 to 8, wherein the Tb₂O₃-based glass material substantially does not contain Sb₂O₃ and As₂O₃. **Claim 10** The manufacturing method of the glass material according to any one of claims 1 to 9, wherein the glass material has a light transmittance of 70% or more at a wavelength of 532 nm.

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