JP2018008839A - Glass material and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass material suitable for a magneto-optical element constituting a magnetic device such as an optical isolator, an optical circulator and a magnetic sensor which exhibits high Faraday effect compared to the conventional art and has excellent laser damage resistance.SOLUTION: There is provided a glass material which comprises, in mol%, 50 to less than 75% of TbOand more than 5 to less than 50% of PO, wherein the content of BOpreferably is 0 to less than 45% and the content of SiOpreferably is 0 to less than 45%. There is provided a method for producing a glass material which comprises a step of heating and melting a glass raw material lump 12 in a state where the glass raw material lump 12 is floated and held to obtain molten glass, followed by cooling the molten glass.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a glass material suitable for a magneto-optical element constituting a magnetic device such as an optical isolator, an optical circulator, and a magnetic sensor, and a manufacturing method thereof.

  It is known that a glass material containing terbium oxide, which is a paramagnetic compound, exhibits a Faraday effect which is one of magneto-optical effects. The Faraday effect is an effect of rotating the polarization plane of linearly polarized light passing through a material placed in a magnetic field. Such an effect is mainly used for an optical isolator used for the purpose of preventing damage due to return light of a laser light source. Or it is utilized also for the magnetic field sensor.

  The optical rotation (rotation angle of the polarization plane) θ by the Faraday effect is expressed by the following equation, where H is the strength of the magnetic field and L is the length of the substance through which the polarized light passes. In the formula, V is a constant depending on the type of substance, and is called Verde's constant. The Verde constant is a positive value for a diamagnetic material and a negative value for a paramagnetic material. The greater the absolute value of the Verde constant, the greater the absolute value of the optical rotation, resulting in a large Faraday effect.

    θ = VHL

Conventionally, as a glass material showing the Faraday _{effect, SiO 2 -B 2 O 3 -Al} 2 O 3 -Tb 2 O 3 based glass material (see Patent Document _{1), P 2 O 5 -B} 2 O 3 -Tb 2 An O ₃ -based glass material (see Patent Document 2) or a P ₂ O ₅ -TbF ₃ -RF ₂ (R is an alkaline earth metal) -based glass material (see Patent Document 3) is known.

Japanese Patent Publication No.51-46524 Japanese Patent Publication No. 52-32881 Japanese Patent Publication No.55-42942

  Although the above glass materials show some Faraday effect, in recent years, the miniaturization of magnetic devices has been increasingly advanced, so that the Faraday effect has been further improved so that even small (particularly thin) members can exhibit sufficient optical rotation. Is required.

  In recent years, since the laser light source has increased in output, a glass member exhibiting a Faraday effect is also required to have high laser damage resistance (laser damage threshold).

  In view of the above, it is an object of the present invention to provide a glass material that exhibits a Faraday effect greater than that of the prior art and that is excellent in laser damage resistance.

The glass material of the present invention contains, in mol%, Tb ₂ O ₃ 50% or more (however, 50% is not included), P ₂ O ₅ 5-50% (however, 5%, 50% is not included). It is characterized by. The glass material of the present invention has a large Verde constant due to containing a large amount of Tb ₂ O ₃ as described above. As a result, the Faraday effect which is larger than the conventional one is shown. Furthermore, as a result of the investigation by the present inventors, it was found that the laser damage resistance is improved by including P ₂ O ₅ in the glass material. As described above, glass materials containing a large amount of Tb ₂ O ₃ are generally difficult to vitrify. However, according to the containerless floating method described later, it is possible to easily vitrify even such a composition that is difficult to vitrify.

In the glass material of the present invention, the content of Tb ₂ O ₃ is preferably 75% or less in terms of mol%. If the content of Tb ₂ O ₃ is in the above range, vitrification can be performed relatively easily.

The glass material of the present invention may further contain, in mol%, B ₂ O ₃ 0 to 45% (excluding 45%) and Al ₂ O ₃ 0 to 45% (excluding 45%). preferable. Since B ₂ O ₃ and Al ₂ O ₃ are components constituting a glass skeleton, vitrification can be performed relatively easily by containing these components.

The glass material of the present invention further contains, in mol%, B ₂ O ₃ 0 to 45% (however, 45% is not included), Al ₂ O ₃ 0 to 45% (however, 45% is not included). Also good. Since B ₂ O ₃ and Al ₂ O ₃ are components that constitute a glass skeleton and extend the vitrification range, vitrification is facilitated by containing these components.

The glass material of the present invention may further contain SiO ₂ 0 to 45% (but not 45%) in mol%. Since SiO ₂ is a component that constitutes a glass skeleton and widens the vitrification range, vitrification is facilitated by containing the component.

  The glass material of the present invention can be used as a magneto-optical element. For example, the glass material of the present invention can be used as a Faraday rotation element which is a kind of magneto-optical element. By using it for the above application, the effects of the present invention can be enjoyed.

  The method for producing a glass material according to the present invention is a method for producing the above glass material, and after the glass material lump is suspended and held, the glass material lump is heated and melted to obtain a molten glass. And a step of cooling the molten glass.

Generally, a glass material is produced by melting a raw material in a melting container such as a crucible and cooling (melting method). However, the glass material of the present invention has a composition containing a large amount of Tb ₂ O ₃ that does not basically constitute a glass skeleton as described above, and is a material that is difficult to vitrify. There is a problem that crystallization proceeds from the contact interface with the substrate.

  Even if the composition is difficult to vitrify, it can be vitrified by eliminating contact at the interface with the melting vessel. As such a method, a containerless floating method in which a raw material is melted and cooled in a suspended state is known. When this method is used, since the molten glass hardly comes into contact with the melting vessel, crystallization starting from the interface with the melting vessel can be prevented, and vitrification becomes possible.

  The glass material of the present invention exhibits a Faraday effect that is greater than that of the conventional glass material and is excellent in laser damage resistance. Therefore, it is particularly suitable as a Faraday rotator used in an optical isolator for a high-power laser light source.

It is typical sectional drawing which shows one Embodiment of the apparatus for manufacturing the glass material of this invention.

The glass material of the present invention contains, in mol%, Tb ₂ O ₃ 50% or more (however, 50% is not included), P ₂ O ₅ 5-50% (however, 5%, 50% is not included). It is characterized by. The reason for limiting the glass composition in this way will be described below. In the following description regarding the content of each component, “%” means “mol%” unless otherwise specified.

Tb ₂ O ₃ is a component that increases the Faraday effect by increasing the absolute value of the Verde constant. The content of Tb ₂ O ₃ is 50% or more (however, 50% is not included), preferably 51% or more, particularly preferably 52% or more. When the content of Tb ₂ O ₃ is too small, the absolute value of the Verdet constant is reduced, a sufficient Faraday effect is difficult to obtain. On the other hand, if the content of Tb ₂ O ₃ is too large, vitrification tends to be difficult, and therefore it is preferably 75% or less, 70% or less, particularly 69% or less.

The content of Tb ₂ O ₃ in the present invention is a representation in terms of Tb present in the glass to the oxide of any trivalent.

The magnetic moment that causes the Verde constant for Tb is greater for Tb ³⁺ than for Tb ⁴⁺ . Therefore, the larger the ratio of Tb ^{3+ in} the glass material, the greater the Faraday effect, which is preferable. Specifically, the ratio of Tb ^{3+ in} the total Tb is preferably 50% or more, 60% or more, 70% or more, 80% or more, and particularly 90% or more in mol%.

P ₂ O ₅ is a component that improves the laser damage resistance. Moreover, it becomes a glass skeleton and has the effect of expanding the vitrification range. The content of P ₂ O ₅ is 5 to 50% (however, 5% and 50% are not included), 5.1 to 45%, 5.5 to 40%, 5.7 to 30%, particularly 6 to 5%. It is preferably 25%. When the content of P ₂ O ₅ is too small, the effect is difficult to obtain. On the other hand, when the content of P ₂ O ₅ is too large, it is difficult enough Faraday effect. Moreover, thermal stability tends to be lowered.

  In addition to the above components, the glass material of the present invention can contain various components shown below.

B ₂ O ₃ becomes a glass skeleton and is a component that widens the vitrification range. However, since B ₂ O ₃ does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of B ₂ O ₃ is preferably 0 to 45% (but not 45%), 1 to 44%, 2 to 40%, particularly 5 to 35%.

Al ₂ O ₃ is a component that forms a glass skeleton as an intermediate oxide and widens the vitrification range. However, since Al ₂ O ₃ does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Accordingly, the content of Al ₂ O ₃ is 0 to 45% (but not 45%), 0.1 to 40%, 0.5 to 30%, 0.8 to 20%, particularly 1 to 15%. Preferably there is.

SiO ₂ becomes a glass skeleton and is a component that widens the vitrification range. However, since SiO ₂ does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of SiO ₂ is preferably 0 to 45% (but not 45%), 0 to 40%, 0 to 30%, particularly preferably 0 to 20%.

La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ , and Y ₂ O ₃ have the effect of improving the stability of vitrification. However, if the content is too large, it becomes difficult to vitrify. Therefore, the contents of La ₂ O ₃ , Gd ₂ O ₃ , Yb ₂ O ₃ and Y ₂ O ₃ are each preferably 10% or less, particularly preferably 5% or less.

Dy ₂ O ₃ , Eu ₂ O ₃ and Ce ₂ O ₃ improve the stability of vitrification and contribute to the improvement of the Verde constant. However, when the content is too large, it becomes difficult to vitrify. Therefore, the contents of Dy ₂ O ₃ , Eu ₂ O ₃ and Ce ₂ O ₃ are each preferably 15% or less, particularly preferably 10% or less. The contents of Dy ₂ O ₃ , Eu ₂ O ₃ , and Ce ₂ O ₃ are expressed by converting all the components present in the glass into trivalent oxides.

  MgO, CaO, SrO, and BaO have the effect of increasing the vitrification stability and chemical durability. However, since it does not contribute to the improvement of the Verde constant, if the content is too large, it becomes difficult to obtain a sufficient Faraday effect. Therefore, the content of these components is preferably 0 to 10%, particularly preferably 0 to 5%.

Ga ₂ O ₃ has the effect of increasing the glass forming ability and expanding the vitrification range. However, when there is too much the content, it will become easy to devitrify. Further, since the Ga ₂ O ₃ it does not contribute to the improvement of the Verdet constant, when the content is too large, a sufficient Faraday effect difficult to obtain. Therefore, the Ga ₂ O ₃ content is preferably 0 to 6%, particularly preferably 0 to 5%.

Fluorine has the effect of increasing the glass forming ability and expanding the vitrification range. However, if its content is too large, it may volatilize during melting, causing a compositional change or affecting the stability of vitrification. Therefore, the content of fluorine _{(F 2} equivalent) 0-10%, 0-7%, particularly preferably 0 to 5%.

Sb ₂ O ₃ can be added as a reducing agent. However, the content of Sb ₂ O ₃ is preferably 0.1% or less in order to avoid coloring or in consideration of environmental load.

  The glass material of the present invention preferably has a light transmission loss as small as possible particularly when used as a magneto-optical element such as an Faraday rotator of an isolator. Therefore, the light transmittance of the glass material of the present invention is preferably 50% or more, 60%, particularly 70% or more at a wavelength of 633 nm.

  The glass material of the present invention can be produced, for example, by a containerless floating method. FIG. 1 is a schematic cross-sectional view showing an example of a manufacturing apparatus for producing a glass material by a containerless floating method. Hereinafter, the manufacturing method of the glass material of this invention is demonstrated, referring FIG.

  The glass material manufacturing apparatus 1 has a mold 10. The mold 10 also serves as a melting container. The molding die 10 has a molding surface 10a and a plurality of gas ejection holes 10b opened in the molding surface 10a. The gas ejection hole 10b is connected to a gas supply mechanism 11 such as a gas cylinder. Gas is supplied from the gas supply mechanism 11 to the molding surface 10a via the gas ejection hole 10b. The type of gas is not particularly limited, and may be, for example, air or oxygen, or a reducing gas containing nitrogen gas, argon gas, helium gas, carbon monoxide gas, carbon dioxide gas, or hydrogen. Good.

  When manufacturing a glass material using the manufacturing apparatus 1, first, the glass raw material lump 12 is arrange | positioned on the molding surface 10a. As the glass raw material block 12, for example, a raw material powder integrated by press molding or the like, a sintered body obtained by integrating raw material powder by press molding or the like, and a composition equivalent to the target glass composition are used. For example, an aggregate of crystals.

  Next, the glass raw material block 12 is floated on the molding surface 10a by ejecting gas from the gas ejection holes 10b. That is, the glass raw material block 12 is held in a state where it is not in contact with the molding surface 10a. In this state, the glass material block 12 is irradiated with laser light from the laser light irradiation device 13. Thereby, the glass raw material lump 12 is heated and melted to be vitrified to obtain molten glass. Thereafter, the glass material can be obtained by cooling the molten glass. In the step of heating and melting the glass raw material lump 12 and the step of cooling until the temperature of the molten glass and further the glass material is at least the softening point or less, at least gas ejection is continued, and the glass raw material lump 12, molten glass, Furthermore, it is preferable to suppress contact between the glass material and the molding surface 10a. The glass raw material block 12 may be floated on the molding surface 10a using a magnetic force generated by applying a magnetic field, or the glass raw material block 12 may be floated on the molding surface 10a using a sound wave. Also good. In addition to the method of irradiating laser light, the method of heating and melting may be radiant heating.

  EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to these Examples.

  Table 1 shows examples and comparative examples of the present invention.

  Each sample was produced as follows. First, a raw material prepared so as to have a glass composition shown in the table was press-molded, and sintered at 700 to 1400 ° C. for 6 hours to prepare a glass raw material lump.

Next, the glass raw material lump was coarsely pulverized using a mortar to obtain small pieces of 0.05 to 1.5 g. A glass material (diameter: about 1 to 10 mm) was prepared by a containerless floating method using an apparatus according to FIG. 1 using the obtained pieces of glass raw material lump. A 100 W CO ₂ laser oscillator was used as the heat source. Moreover, nitrogen gas was used as gas for suspending a glass raw material lump, and it supplied with the flow volume of 1-30 L / min.

  About the obtained glass material, the Verde constant, the laser damage threshold value, and the light transmittance were measured as follows.

  The Verde constant was measured using the rotational analyzer method. Specifically, the obtained glass material was polished so as to have a thickness of 1 mm, the Faraday rotation angle at a wavelength of 400 to 1100 nm was measured in a magnetic field of 10 kOe, and the Verde constant was calculated.

  The laser damage threshold was measured by a N-on-1 method using a single mode Nd: YAG laser having a wavelength of 1064 nm and a pulse width of 10 ns. The N-on-1 method is to irradiate a laser beam while continuously increasing the incident energy density to a fixed irradiation spot in the target member, and confirm the state of the target member for each irradiation, and damage Is defined as a laser damage threshold.

  The light transmittance was measured using a spectrophotometer (UV-3100 manufactured by Shimadzu Corporation). Specifically, the obtained glass material was polished to have a thickness of 1 mm, and the light transmittance at 633 nm was read from the light transmittance curve obtained by measuring the transmittance at a wavelength of 300 to 1400 nm. . The light transmittance is an external transmittance including reflection.

  As apparent from Table 1, the glass materials of Examples 1 to 7 have a wavelength of -0.53 to -0.80 at a wavelength of 633 nm, -0.27 to -0.41 at a wavelength of 850 nm, and -0.17 at a wavelength of 1064 nm. A Verde constant of .about.-0.25 was shown. On the other hand, the Verde constant of the glass material of the comparative example was −0.25 at a wavelength of 633 nm, −0.13 at a wavelength of 850 nm, and −0.10 at a wavelength of 1064 nm, and the absolute value was small.

The glass material of Example 1-7 as shown in Table 1, while the laser damage threshold was as large as 26~57J / cm ^2, the laser damage threshold of the glass material of the comparative example and 19J / cm ² It was small.

  The glass material of the present invention is suitable as a magneto-optical element constituting a magnetic device such as an optical isolator, an optical circulator, or a magnetic sensor.

1: Glass material manufacturing apparatus 10: Mold 10a: Molding surface 10b: Gas ejection hole 11: Gas supply mechanism 12: Glass raw material block 13: Laser beam irradiation apparatus

Claims (7)

A glass material characterized by containing, in mol%, 50% or more of Tb ₂ O ₃ (excluding 50%) and 5-50% of P ₂ O ₅ (excluding 5% and 50%). The glass material according to claim 1, wherein the content of Tb ₂ O ₃ is 75% or less. Furthermore, in _{mol%, B 2 O 3 0~45%} ( although 45% is not _included), claim 1, characterized in that it contains _Al 2 O 3 _0~45% (but 45% is not included) Or the glass material of 2. Furthermore, in _mol%, SiO 2 0~45% (although 45% is not included) glass material according to claims 1 to 3, characterized in that it contains.   The glass material according to claim 1, wherein the glass material is used as a magneto-optical element.   The glass material according to claim 5, wherein the glass material is used as a Faraday rotation element.   It is a method for manufacturing the glass material as described in any one of Claims 1-6, Comprising: With the glass raw material lump suspended, the said glass raw material lump is heat-melted and molten glass is obtained. After that, the manufacturing method of the glass material characterized by including the process of cooling the said molten glass.