Glass materials and magneto-optical elements

Abstract

To provide a glass material and a magneto-optic element in which a thermal lensing effect is reduced.SOLUTION: This glass material contains, in mol%, Tb2O3 of 10%-90%, B2O3+Al2O3+SiO2+P2O5 of 1%-89%, and FeO+Fe2O3 of 0.01 ppm-100 ppm, and also contains CeO2 of 0.001-1% in outer percentage.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to glass materials and magneto-optical elements. [Background technology]

[0002] Paramagnetic glass materials are known to exhibit the Faraday effect, a magneto-optical effect. The Faraday effect is the rotation of linearly polarized light passing through a material placed in a magnetic field. Magneto-optical elements that utilize this effect (e.g., Faraday rotators) are used in magneto-optical devices such as optical isolators.

[0003] Examples of paramagnetic glass materials include the SiO2-B2O3-Al2O3-Tb2O3 system (Patent Document 1) and the P2O5-B2O3-Tb2O3 system (Patent Document 2). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 51-46524 [Patent Document 2] Special Publication No. 52-32881 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In recent years, the output power of laser light irradiated onto magneto-optical devices has been increasing. When the output power of the laser light increases, the temperature of the magneto-optical element rises, making it more susceptible to changes in beam diameter due to the thermal lensing effect.

[0006] In view of the above, the present invention aims to provide a glass material and a magneto-optical element that reduce the thermal lensing effect. [Means for solving the problem]

[0007] The glass material of the present invention is characterized by containing, in mol% terms, Tb2O3 10% to 90%, B2O3 + Al2O3 + SiO2 + P2O 51% to 89%, FeO + Fe2O3 0.01 ppm to 100 ppm, and further containing CeO2 0.001% to 1% by external weighting.

[0008] The glass material of the present invention preferably contains, in mol% terms, 30% to 70% B2O, 30% to 70% Al2O, 20% to 70% SiO2O, and 50% to 10% P2O.

[0009] The glass material of the present invention preferably contains, in molar percentage, more than 12% to 40% of B2O3, 1% to 20% of Al2O3, 20% to 40% of SiO2, and 50% to 5% of P2O.

[0010] The glass material of the present invention preferably contains less than 35% Pr2O and less than 35% Dy2O in mol%.

[0011] The glass material of the present invention has Tb relative to total Tb 3+ It is preferable that the proportion is 55% or more in mole percent.

[0012] The glass material of the present invention preferably has a light transmittance of 70% or more at a wavelength of 1064 nm.

[0013] The magneto-optical element of the present invention is characterized by using the glass material described above. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a glass material and a magneto-optical element that reduce the thermal lensing effect. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic cross-sectional view showing one embodiment of an apparatus for manufacturing glass material according to the present invention. [Modes for carrying out the invention]

[0016] The glass material of the present invention contains, in mol%, 10% to 90% of Tb2O3, 1% to 89% of B2O3 + Al2O3 + SiO2 + P2O5, 0.01 ppm to 100 ppm of FeO + Fe2O3, and further contains 0.001% to 1% of CeO2 by external addition. Here, "further contains 0.001% to 1% of CeO2 by external addition" means that the content of CeO2 is 0.001% to 1% with respect to the total content of 100% of the components other than CeO2 in mol% (that is, the total amount is 100.001% to 101%).

[0017] The reasons for defining the glass composition as above and the content of each component will be described below. In the following description, unless otherwise specified, "%" means "mol%". Also, the "visible to near-infrared wavelength range" in the following description is the wavelength range used for visible to near-infrared lasers, and unless otherwise specified, it means a wavelength range of 300 nm to 2000 nm, particularly 300 nm to 1100 nm.

[0018] Tb2O3 is a component that increases the absolute value of the Verdet constant and enhances the Faraday effect. The content of Tb2O3 is 10% to 90%, preferably 10% to 80%, 10% to 70%, 10% to 60%, 12% to 50%, 12% to 51%, 15% to 49%, 16% to 46%, 18% to 45%, 20% to 44%, 21% to 43%, 22% to 41%, particularly 26% to 40%. When particularly desiring to increase the Verdet constant, the content of Tb2O3 is preferably 52% to 80%, 53% to 75%, 54% to 71%, 55% to 69%, 56% to 67%, 57% to 65%, particularly 58% to 64%. If the content of Tb2O3 is too low, it becomes difficult to obtain the above effects. If the content of Tb2O3 is too high, it becomes difficult to vitrify. Also, the light transmittance of the glass material tends to decrease. Therefore, when particularly desiring to increase the Verdet constant, it is preferable to limit the content of Tb2O3 as above and contain 1% or more of Al2O3. This suppresses the devitrification of the glass material and makes it easier 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.

[0019] Tb with respect to total Tb 3+ The ratio 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 with respect to total Tb 4+ can be reduced. Tb 4+ has absorption at wavelengths of 300 nm to 1100 nm, and the light transmittance of the glass material tends to decrease. Therefore, by setting the ratio of Tb with respect to total Tb 3+ to the above value, absorption of laser light in the visible to near-infrared wavelength region can be suppressed, and heat generation of the glass material can be easily suppressed. Thus, the thermal lens effect can be easily suppressed.

[0020] FeO and Fe2O3 are components that decrease the light transmittance in the visible to near-infrared wavelength region and tend to cause the thermal lens effect. Specifically, FeO (Fe 2+ ) has a broad absorption having a peak around a wavelength of 1200 nm. Therefore, the glass material absorbs laser light in the visible to near-infrared wavelength region and generates heat, and the thermal lens effect is likely to occur. Also, Fe2O3 (Fe 3+ ) may be reduced to FeO during the melting process. Therefore, in the glass material of the present invention, the content of FeO + Fe2O3 (total amount of FeO and Fe2O3) is 0.01 ppm to 100 ppm, preferably 0.01 ppm to 20 ppm, 0.05 ppm to 15 ppm, 0.1 ppm to 14 ppm, 0.2 ppm to 13 ppm, 0.3 ppm to 11 ppm, 0.4 ppm to 10 ppm, 0.5 ppm to 9 ppm, particularly 1 ppm to 8 ppm. If the content of FeO + Fe2O3 is too small, the manufacturing cost tends to increase. [[ID=​​​​​The oxidizing effect is reduced. If too much CeO2 is added, the light transmittance of the glass material tends to decrease.

[0022] Thus, the glass material of the present invention contains FeO and Fe2O3, which tend to reduce light transmittance and cause a thermal lensing effect, and CeO2, which functions as an oxidizing agent, as essential components. This configuration suppresses the decrease in light transmittance of the glass material in the visible to near-infrared wavelength range and reduces laser light absorption. Therefore, the glass material of the present invention can reduce the thermal lensing effect.

[0023] The ratio of CeO2 content (amount added) to FeO+Fe2O3 content, CeO2 / (FeO+Fe2O3), is preferably 10-10000, 30-10000, 100-7500, 100-5000, and especially 100-3000. By satisfying the above ratios for CeO2 content (amount added) and FeO+Fe2O3 content, the thermal lensing effect is more easily suppressed.

[0024] B2O3, Al2O3, SiO2, and P2O5 form the glass skeleton, expanding the vitrification range and stabilizing vitrification. The content of B2O3+Al2O3+SiO2+P2O5 (total amount of B2O3, Al2O3, SiO2, and P2O5) is between 1% and 89%, and is preferably 1% to 86%, 6% to 85%, 11% to 83%, 16% to 81%, 21% to 79%, 26% to 77%, 31% to 75%, 36% to 73%, 41% to 71%, 46% to 70%, and 47% to 69%. If the content of B2O3+Al2O3+SiO2+P2O5 is too low, vitrification becomes difficult. If the content of B2O3+Al2O3+SiO2+P2O5 is too high, it becomes difficult to obtain a sufficient Faraday effect. The preferred ranges for each component are as follows:

[0025] The B2O3 content is preferably 0%-89%, 0%-88%, 0%-87%, 0%-85%, 0%-75%, 0%-70%, 0%-66%, 0%-56%, 0%-51%, 1%-44%, 1%-40%, 1%-40%, 2%-40%, 4%-40%, 5%-40%, 10%-40%, over 12%-40%, and particularly preferably 13%-40%.

[0026] The Al2O3 content is preferably 0%-89%, 0%-88%, 0%-87%, 0%-85%, 0%-75%, 0%-70%, 0%-66%, 0%-56%, 0%-51%, 1%-44%, 1%-40%, 1%-30%, and particularly preferably 1%-20%.

[0027] The SiO2 content is preferably 0%-89%, 0%-88%, 0%-87%, 0%-85%, 0%-75%, 0%-70%, 0%-66%, 0%-56%, 0%-51%, 0%-50%, 0%-49%, 0%-40%, 1%-40%, 5%-40%, and particularly preferably 10%-40%.

[0028] The P2O5 content is preferably 0%-89%, 0%-88%, 0%-87%, 0%-85%, 0%-75%, 0%-70%, 0%-66%, 0%-56%, 0%-51%, 0%-40%, 0%-30%, 0%-25%, 0%-20%, 0%-20%, 0%-15%, 0%-10%, 0%-5%, and particularly preferably 1%-5%.

[0029] In addition to the above components, the glass material of the present invention may contain the following components.

[0030] GeO2 forms the glass skeleton, expanding the vitrification range and stabilizing vitrification. The GeO2 content is preferably 0%-60%, 0%-55%, 0%-50%, 0%-45%, 0%-40%, and especially 0%-35%. Too much GeO2 makes it difficult to obtain a sufficient Faraday effect.

[0031] ZnO is a component that stabilizes vitrification. The ZnO content is preferably 0%-20%, 0%-15%, 0%-13%, 0%-10%, 0%-8%, and especially preferably 0%-5%. Too much ZnO makes devitrification more likely and makes it difficult to obtain a sufficient Faraday effect.

[0032] La2O3, Gd2O3, Y2O3, and Yb2O3 are components that stabilize vitrification. The preferred content of La2O3, Gd2O3, Y2O3, and Yb2O3 is 10% or less, 7% or less, 5% or less, 4% or less, 2% or less, and especially 1% or less, respectively. If the content of these components is too high, vitrification becomes more difficult. There is no particular lower limit to the content of La2O3, Gd2O3, Y2O3, and Yb2O3, but for example, each is 0.1% or more.

[0033] Dy2O3, Eu2O3, Pr2O3, and Sm2O3 have light absorption in the visible to near-infrared wavelength range. Therefore, the content of Dy2O3, Eu2O3, Pr2O3, and Sm2O3 is preferably less than 5%, 3% or less, 2% or less, 1% or less, 500 ppm or less, and especially preferably 100 ppm or less, respectively. If the content of these components is too high, the light transmittance in the visible to near-infrared wavelength range tends to decrease. Note that Dy, Eu, Pr, and Sm exist in the glass in divalent, trivalent, and tetravalent states, but in this invention, they are represented as Dy2O3, Eu2O3, Pr2O3, and Sm2O3, respectively. There is no particular lower limit to the content of Dy2O3, Eu2O3, Pr2O3, and Sm2O3, but for example, each is 0.001 ppm or more.

[0034] MgO, CaO, SrO, and BaO are components that stabilize vitrification and enhance chemical durability. The preferred content of MgO, CaO, SrO, and BaO is 0% to 10%, particularly 0% to 5%. If the content of these components is too high, it becomes difficult to obtain a sufficient Faraday effect.

[0035] Ga2O3 is a component that stabilizes vitrification and easily broadens the vitrification range. The Ga2O3 content is preferably 0% to 6%, 0% to 5%, 0% to 4%, and especially 0% to 2%. Too much Ga2O3 content makes devitrification more likely and makes it difficult to obtain a sufficient Faraday effect.

[0036] Fluorine is a component that enhances glass-forming ability and easily broadens the vitrification range. The fluorine content (F2 equivalent) is preferably 0% to 10%, 0% to 7%, 0% to 5%, 0% to 3%, 0% to 2%, and particularly preferably 0% to 1%. If the fluorine content is too high, the component may volatilize during melting, adversely affecting vitrification. It may also increase the likelihood of striation formation.

[0037] The glass material preferably has a light transmittance of 70% or more, 75% or more, 80% or more, and particularly 83% or more at a wavelength of 1064 nm. Furthermore, at a wavelength of 633 nm, it is preferable that the light transmittance is 60% or more, 65% or more, 70% or more, and particularly 75% or more. Moreover, at a wavelength of 532 nm, it is preferable that the light transmittance is 30% or more, 50% or more, 60% or more, and particularly 70% or more. Note that the above light transmittance values ​​are for when the thickness of the glass material is 1 mm.

[0038] The glass material of the present invention has the above configuration, which reduces the thermal lensing effect. Therefore, the glass material of the present invention can be suitably used in magneto-optical elements (for example, Faraday rotors) that constitute magnetic devices such as optical isolators, optical circulators, and magnetic sensors.

[0039] The glass material of the present invention can be manufactured, for example, by a containerless levitation method. Figure 1 is a schematic cross-sectional view showing one embodiment of an apparatus for manufacturing the glass material of the present invention. The method for manufacturing the glass material of the present invention will be described below with reference to Figure 1.

[0040] The glass material manufacturing apparatus 1 has a mold 10. The mold 10 also serves as a melting container. The mold 10 has a molding surface 10a and a plurality of gas ejection holes 10b opening in the molding surface 10a. The gas ejection holes 10b are connected to a gas supply mechanism 11 such as a gas cylinder. Gas is supplied from this gas supply mechanism 11 to the molding surface 10a via the gas ejection holes 10b. The type of gas is not particularly limited and may be air or oxygen, or a reducing gas containing nitrogen gas, argon gas, helium gas, carbon monoxide gas, carbon dioxide gas, or hydrogen. Among these, it is preferable to use an inert gas from the viewpoint of suppressing oxidation of the glass material and ensuring safety.

[0041] Using the glass material manufacturing apparatus 1, glass materials can be manufactured as follows. First, a glass raw material block 12 is placed on the molding surface 10a. Examples of glass raw material blocks 12 include a material formed by integrating raw material powders by press molding, a sintered body formed by integrating raw material powders by press molding and then sintering it, and an aggregate of crystals having a composition equivalent to the target glass composition.

[0042] Next, the glass raw material mass 12 is suspended on the molding surface 10a by ejecting gas from the gas ejection hole 10b. That is, the glass raw material mass 12 is held in a state where it is not in contact with the molding surface 10a. In this state, laser light is irradiated onto the glass raw material mass 12 from the laser light irradiation device 13. This heats and melts the glass raw material mass 12, causing it to vitrify and obtain molten glass. After that, the molten glass is cooled to obtain glass material. At this time, the molten glass and glass material are cooled until their temperatures are at least below their softening point. In the steps of heating and melting the glass raw material mass 12 and cooling the molten glass and glass material until their temperatures are at least below their softening point, it is preferable to continue ejecting gas at least to suppress contact between the glass raw material mass 12, the molten glass, and the glass material and the molding surface 10a. Alternatively, the glass raw material mass 12 may be suspended on the molding surface 10a by utilizing the magnetic force generated by applying a magnetic field. In addition to the method of irradiating with laser light, the glass raw material mass 12 may also be heated and melted by radiant heating or the like.

[0043] The method for manufacturing the glass material of the present invention is not limited to the containerless levitation method described above. For example, the glass material of the present invention may be manufactured by crucible melting. In the case of crucible melting, a large amount of raw material powder can be melted at once, making it easier to obtain large glass materials. Large glass materials can be suitably used for applications such as high-power lasers. [Examples]

[0044] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0045] Tables 1-5 show Examples 1-24 and Comparative Examples 25-27 of the present invention.

[0046] [Table 1]

[0047] [Table 2]

[0048] [Table 3]

[0049] [Table 4]

[0050] [Table 5]

[0051] Each sample was prepared as follows: First, the raw materials were mixed to achieve the glass composition shown in Tables 1-5 and then press-molded. The press-molded raw materials were then sintered at 800°C for 5 hours to produce glass raw material ingots.

[0052] Next, the glass raw material was coarsely crushed in a mortar to obtain 1g pieces. Then, using the glass raw material pieces and the apparatus shown in Figure 1, glass material (approximately 9mm in diameter) was produced by containerless levitation. A 100W CO2 laser oscillator was used as the heat source. Nitrogen gas was used to levitate the glass raw material, with a supply flow rate of 1 to 30 L / min. The obtained glass material was annealed in a 4%-H2 / N2 atmosphere at 770°C for 6 hours, after which the following measurements were performed. The results are shown in Tables 1 to 5.

[0053] The Verde constant was measured using the rotational analyzer method. Specifically, the obtained glass material was polished to a thickness of 1 mm, and the Faraday rotation angle was measured in a magnetic field of 10 kOe in the wavelength range of 500 nm to 1100 nm, and the Verde constant at a wavelength of 1064 nm was calculated.

[0054] Light transmittance was measured using a spectrophotometer (V-670, JASCO Corporation). Specifically, the obtained glass material was polished to a thickness of 1 mm, and the light transmittance at a wavelength of 1064 nm was read from the light transmittance curve. Note that the light transmittance is the external transmittance, including reflection.

[0055] Tb for all Tb 3+ The proportion was measured using X-ray absorption fine structure analysis (XAFS). Specifically, the spectrum of the X-ray absorption edge structure region (XANES) was obtained, and the proportion of Tb relative to total Tb was calculated from the shift amount of the peak position of each Tb ion. 3+ The proportion (mol%) was calculated.

[0056] The beam diameter change rate was measured as follows. First, laser light with a wavelength of 1064 nm and output power of 10 W and 50 W was incident on a glass sample processed to a thickness of 3 mm, with a beam diameter of φ1 mm, and the size of the beam diameter at a position 300 mm from the sample was measured. The beam diameter was 1 / e 2The value was set to [value]. Next, using the beam diameter at an output of 10mW as the reference, the rate of change in beam diameter when the output was increased to 50W was calculated. Note that even without a sample, a change in beam diameter was observed due to the thermal lensing effect of the collimating lens, so the beam diameter change rate was defined as the measured beam diameter change rate minus the change in beam diameter when there was no sample.

[0057] As shown in Tables 1-5, the glass materials of Examples 1-24 had an absolute value of Verde constant of 0.01-0.226 min / Oe·cm at a wavelength of 1064 nm. Furthermore, the light transmittance was 80% or higher at 1064 nm in all cases, demonstrating good light transmittance. The beam diameter change rate was 17% or less.

[0058] On the other hand, the glass materials in Comparative Examples 25-27 showed a beam diameter change rate of 30% or more. [Industrial applicability]

[0059] The glass material of the present invention can be suitably used in magneto-optical elements (for example, Faraday rotors) that constitute magnetic devices such as optical isolators, optical circulators, and magnetic sensors.

Claims

1. in mol%, Tb ２ O ３ 10% to 80%, B ２ O ３ + Al ２ O ３ + SiO ２ + P ２ O ５ 16% to 89%, FeO + Fe ２ O ３ contains 0.01 ppm to 100 ppm, and further contains 0.001% to 1% of CeO by external division, a glass material.​​

2. In mol%, B ２ O ３ 0% to 70%, Al ２ O ３ 0% to 70%, SiO ２ 0% to 70%, P ２ O ５ The glass material according to claim 1, containing 0% to 10%.

3. In mole percent, B ２ O ３ More than 12% to 40%, Al ２ O ３ 1% to 20%, SiO ２ 0% to 40%, P ２ O ５ The glass material according to claim 2, containing 0% to 5%.

4. In mole percent, Pr ２ O ３ Less than 5%, D ２ O ３ A glass material according to any one of claims 1 to 3, containing less than 5%.

5. Tb for all Tb ３＋ The glass material according to any one of claims 1 to 4, wherein the proportion of is 55% or more in mol%.

6. A glass material according to any one of claims 1 to 5, wherein the light transmittance at a wavelength of 1064 nm is 70% or more.

7. A magneto-optical element using the glass material described in any one of claims 1 to 6.

Images