Halide glass, optical element, and optical device

Abstract

The present invention provides: a halide glass which does not undergo devitrification even if a rare earth element is introduced; an optical element; and an optical device.　The halide glass contains, in terms of cation%, 11-60% of Al, 0.1-20% of Sc, a total of 10-88.7% of Mg, Ca, Sr, and Ba, and 0.01-20% of Ln (Ln is at least one selected from among Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm), while containing 70-100% of F in terms of anion%.

Description

Halide glass, optical elements and optical devices

[0001] The present invention relates to halide glasses, optical elements, and optical devices.

[0002] Conventionally, so-called fluorescent glass, which is glass doped with rare earth ions, has been used as a laser medium or a phosphor in a wide range of fields, such as communications, medicine, processing, and nuclear power, due to its ease of manufacture, flexibility in composition, homogeneity, moldability, etc. Along with the diversification of such applications, there has been an increasing demand in recent years for fluorescent glass with higher brightness and improved luminous efficiency.

[0003] For example, Patent Document 1 provides fluorescent glass made of fluoride glass containing rare earth elements.

[0004] Japanese Patent Application Publication No. 8-208265

[0005] In view of the above, an object of the present invention is to provide a halide glass, an optical element, and an optical device that do not suffer from devitrification even when a rare earth element is introduced.

[0006] Various aspects of halide glass, optical elements, and optical devices that solve the above problems will now be described.

[0007] The halide glass of Aspect 1 is characterized by containing, in terms of cation %, 11 to 60% Al, 0.1 to 20% Sc, 10 to 88.7% Mg+Ca+Sr+Ba, and 0.01 to 20% Ln (Ln is at least one element selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm), and containing, in terms of anion %, 70 to 100% F.

[0008] The halide glass of embodiment 2 preferably contains, in embodiment 1, 70 to 99.9% F, and 0.1 to 20% Lm (Lm is at least one selected from Cl, Br, and I), expressed in anion %.

[0009] The halide glass of embodiment 3, in embodiment 1 or 2, preferably contains, in cationic %, 0 to 30% Mg, 0 to 30% Ca, 0 to 30% Sr, and 0 to 20% Ba.

[0010] The halide glass of embodiment 4 is any one of embodiments 1 to 3, and preferably contains 0.1 to 20% Y in cationic %.

[0011] The optical element of Aspect 5 is characterized in that it is made of the halide glass of any one of Aspects 1 to 4.

[0012] The optical device of the sixth aspect is characterized by using the optical element of the fifth aspect.

[0013] According to the present invention, it is possible to provide a halide glass, an optical element, and an optical device that do not suffer from devitrification even when a rare earth element is introduced.

[0014] Fig. 1 is a schematic perspective view showing one example of the shape of the glass of the present invention. Fig. 2 is a schematic perspective view showing another example of the shape of the glass of the present invention. Fig. 3 is a schematic view of a laser oscillation device using the glass of the present invention.

[0015] The halide glass of the present invention is characterized by containing, expressed as cation %, 11 to 60% Al, 0.1 to 20% Sc, 10 to 88.7% Mg + Ca + Sr + Ba, and 0.01 to 20% Ln (Ln is at least one element selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm), and, expressed as anion %, 70 to 100% F. The reasons for limiting the content of each component as described above are as follows. In the description of the content of each component, % denotes cation % or anion % unless otherwise specified. Furthermore, unless otherwise specified, each element refers to an ion, and its valence is not limited.

[0016] Al is an essential component that can increase stability against crystallization and chemical durability. The Al content is 11 to 60% in terms of cation %. If the Al content is too low, crystallization is likely to occur and chemical durability is likely to deteriorate. Therefore, the lower limit of the Al content is 11% or more in terms of cation %, preferably 15% or more, 20% or more, and particularly preferably 25% or more. On the other hand, if the Al content is too high, crystallization becomes very likely and it becomes difficult to obtain glass. The upper limit of the Al content is 60% or less in terms of cation %, preferably 55% or less, 50% or less, 45% or less, 40% or less, 35% or less, and particularly preferably 33% or less. The valence of Al is, for example, trivalent, but is not limited to this.

[0017] Sc can improve the dispersibility of rare earth elements in glass. This effect prevents concentration quenching even when rare earth elements are contained at high concentrations, making Sc an essential component. Sc also has the effect of increasing stability against crystallization, making it an essential component for this reason. The Sc content is 0.1 to 20% in terms of cation %. If the Sc content is too low, concentration quenching is likely to occur, making it difficult to obtain sufficient luminescence intensity. Therefore, the lower limit of the Sc content is 0.1% or more in terms of cation %, preferably 1% or more, 3% or more, and particularly preferably 5% or more. On the other hand, if the Sc content is too high, crystallization is likely to occur. Therefore, the upper limit of the Sc content is 20% or less in terms of cation %, preferably 15% or less, 10% or less, and particularly preferably 7% or less. The valence of Sc is, for example, trivalent, but is not limited thereto.

[0018] Mg, Ca, Sr, and Ba are components that tend to increase the stability of glass against crystallization. The content of Mg + Ca + Sr + Ba, expressed in cation %, is 10 to 88.7%. If the content of Mg + Ca + Sr + Ba is too low, the above effects are difficult to achieve. Therefore, the lower limit of the content of Mg + Ca + Sr + Ba, expressed in cation %, is 10% or more, preferably 15% or more, and more preferably 20% or more, 25% or more, 30% or more, 35% or more, 40% or more, and particularly preferably 45% or more. On the other hand, if the content of Mg + Ca + Sr + Ba is too high, crystallization tends to occur. Therefore, the upper limit of the content of Mg + Ca + Sr + Ba, expressed in cation %, is 88.7% or less, preferably 80% or less, 75% or less, 70% or less, 65% or less, 60% or less, and particularly preferably 55% or less. The term "Mg + Ca + Sr + Ba" refers to the total amount of Mg, Ca, Sr, and Ba expressed as cation %. The preferred contents of each of the Mg, Ca, Sr, and Ba components are as follows:

[0019] Mg is a component that tends to increase the stability of glass against crystallization. The Mg content is preferably 0 to 30% in terms of cation %. More specifically, the lower limit of the Mg content is preferably 0% or more in terms of cation %, and more preferably 5% or more, and particularly preferably 10% or more. On the other hand, if the Mg content is too high, crystallization tends to occur. Therefore, the upper limit of the Mg content is preferably 30% or less in terms of cation %, and more preferably 25% or less, 20% or less, and particularly preferably 15% or less. The valence of Mg is exemplified by divalent, but is not limited to this.

[0020] Ca is a component that tends to increase the stability of glass against crystallization. The Ca content is preferably 0 to 30% in terms of cation %. More specifically, the lower limit of the Ca content is preferably 0% or more in terms of cation %, and is preferably 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. On the other hand, if the Ca content is too high, crystallization tends to occur. Therefore, the upper limit of the Ca content is preferably 30% or less in terms of cation %, and is preferably 27% or less, 25% or less, and particularly preferably 20% or less. The valence of Ca is exemplified by divalent, but is not limited to this.

[0021] Sr is a component that enhances the stability of glass against crystallization. The Sr content is preferably 0 to 30% in terms of cation %. More specifically, the lower limit of the Sr content is preferably 0% or more in terms of cation %, and is preferably 1% or more, 5% or more, 8% or more, and particularly preferably 10% or more. On the other hand, if the Sr content is too high, crystallization becomes more likely. Therefore, the upper limit of the Sr content is preferably 30% or less in terms of cation %, and is preferably 27% or less, 25% or less, 23% or less, and particularly preferably 20% or less. The valence of Sr is exemplified by divalent, but is not limited to this.

[0022] Ba is a component that can increase the stability of glass against crystallization. The Ba content is preferably 0 to 20% in terms of cation %. More specifically, the lower limit of the Ba content is preferably 0% or more in terms of cation %, and more preferably 1% or more, 3% or more, and particularly preferably 5% or more. On the other hand, if the Ba content is too high, crystallization tends to occur. Therefore, the upper limit of the Ba content is preferably 20% or less in terms of cation %, and more preferably 15% or less, and particularly preferably 10% or less. The valence of Ba is, for example, divalent, but is not limited to this.

[0023] Ln (Ln is at least one element selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm) functions as a wavelength conversion ion in the glass. These elements can be used alone or in combination of two or more elements. The Ln content is 0.01 to 20% expressed as cation %. If the Ln content is too low, the fluorescence luminous efficiency will be very low, making it difficult to obtain sufficient light output. Therefore, the lower limit, expressed as cation %, is 0.01% or more, preferably 0.1%, and more preferably 0.5% or more, 1.0% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, 3.5% or more, 4.5% or more, 5% or more, and particularly 6% or more. On the other hand, if the Ln content is too high, the glass will be prone to devitrification and will lose its translucency due to crystallization. Furthermore, concentration quenching will result in a very low fluorescence intensity. Therefore, the upper limit, expressed as cation %, is 20% or less, preferably 17% or less, more preferably 15% or less, 13% or less, and particularly preferably 10% or less. Representative ranges of emission wavelengths for each wavelength conversion ion are shown below, but are not limited to these, and the emission wavelengths are not limited to the visible light range of 380 nm to 780 nm, but may also be in the ultraviolet range on the short wavelength side or the infrared range on the long wavelength side.

[0024] Cr is a component that can produce fluorescence at wavelengths around 700 nm to 1700 nm. The Cr content, expressed as cation %, is preferably 0 to 20%. If the Cr content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 700 nm to 1700 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Cr content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, the glass is prone to coloration, which reduces transmittance. Furthermore, concentration quenching significantly reduces the fluorescence luminous efficiency. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Cr is exemplified by trivalent and hexavalent, but is not limited thereto.

[0025] Ce is a component that can produce fluorescence at wavelengths around 300 nm to 500 nm. The Ce content, expressed as cation %, is preferably 0 to 20%. If the Ce content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 300 nm to 500 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Ce content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, the glass is prone to yellow or orange coloration, which reduces transmittance. Furthermore, concentration quenching significantly reduces the fluorescence emission efficiency. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Ce is exemplified by trivalent and tetravalent, but is not limited thereto.

[0026] Nd is a component that can produce fluorescence at wavelengths around 1000 nm to 1200 nm. The Nd content, expressed as cation %, is preferably 0 to 20%. If the Nd content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 1000 nm to 1200 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Nd content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Nd is, for example, trivalent, but is not limited to this.

[0027] Yb is a component that can produce fluorescence at wavelengths around 925 nm to 1100 nm. The Yb content is preferably 0 to 20% in terms of cation %. If the Yb content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 925 nm to 1100 nm. Therefore, the lower limit is preferably 0% or more in terms of cation %, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Yb content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit is preferably 20% or less in terms of cation %, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Yb is exemplified by, but is not limited to, trivalent.

[0028] Er is a component that can produce fluorescence at wavelengths around 1530 to 1620 nm. The Er content, expressed as cation %, is preferably 0 to 20%. If the Er content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 1530 to 1620 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Er content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Er is exemplified as trivalent, but is not limited to this.

[0029] Pr is a component that can produce fluorescence at wavelengths around 630 nm to 670 nm. The Pr content, expressed as cation %, is preferably 0 to 20%. If the Pr content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 630 nm to 670 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Pr content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Pr is exemplified as trivalent, but is not limited to this.

[0030] Sm is a component that can produce fluorescence at wavelengths of approximately 500 nm to 700 nm. The Sm content is preferably 0 to 20% in terms of cationic %. If the Sm content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths of approximately 500 nm to 700 nm. Therefore, the lower limit is preferably 0% or more in terms of cationic %, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Sm content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit is preferably 20% or less in terms of cationic %, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Sm is exemplified by, but is not limited to, trivalent Sm.

[0031] Eu is a component that can produce fluorescence at wavelengths around 550 nm to 650 nm. The Eu content, expressed as cation %, is preferably 0 to 20%. If the Eu content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 550 nm to 650 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Eu content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Eu is exemplified by, but is not limited to, trivalent.

[0032] Tb is a component that can produce fluorescence at wavelengths around 350 nm to 600 nm. The Tb content, expressed as cation %, is preferably 0 to 20%. If the Tb content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 350 nm to 600 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Tb content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit, expressed as cation %, is preferably 20% or less, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Tb is exemplified as trivalent, but is not limited thereto.

[0033] Dy is a component that can produce fluorescence at wavelengths of approximately 250 nm to 600 nm and 2600 nm to 3400 nm. The Dy content, expressed as cation %, is preferably 0 to 20%. If the Dy content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths of approximately 250 nm to 600 nm and 2600 nm to 3400 nm. Therefore, the lower limit, expressed as cation %, is preferably 0% or more, and more preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Dy content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a very low fluorescence intensity. Therefore, the upper limit is preferably 20% or less in terms of cation %, more preferably 17% or less, 15% or less, 13% or less, and particularly preferably 10% or less. The valence of Dy is, for example, trivalent, but is not limited to this.

[0034] Ho is a component that can produce fluorescence at wavelengths around 2050 nm to 2150 nm. The Ho content is preferably 0 to 20% in terms of cationic %. If the Ho content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 2050 nm to 2150 nm. Therefore, the lower limit is preferably 0% or more in terms of cationic %, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Ho content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit is preferably 20% or less in terms of cationic %, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Ho is exemplified by, but is not limited to, trivalent.

[0035] Tm is a component that can produce fluorescence at wavelengths around 1950 nm to 2050 nm. The Tm content is preferably 0 to 20% in terms of cation %. If the Tm content is too low, it becomes difficult to obtain sufficient fluorescence at wavelengths around 1950 nm to 2050 nm. Therefore, the lower limit is preferably 0% or more in terms of cation %, and is preferably 0.01% or more, 0.1% or more, 0.2% or more, 0.3% or more, 0.4% or more, 0.5% or more, 0.7% or more, 1% or more, 2% or more, 3% or more, 5% or more, and particularly 6% or more. On the other hand, if the Tm content is too high, the glass is prone to devitrification and loss of translucency due to crystallization. Furthermore, concentration quenching causes a significant decrease in fluorescence intensity. Therefore, the upper limit is preferably 20% or less in terms of cation %, and is preferably 17% or less, 15% or less, 13% or less, and particularly 10% or less. The valence of Tm is exemplified by, but is not limited to, trivalent.

[0036] F is an essential component for forming the halide glass of the present invention. The F content is 70 to 100% in anion %. If the F content is too low, it becomes difficult to form glass. Therefore, the lower limit, in anion %, is 70% or more, preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more. The upper limit is 100% or less, preferably 99.9% or less. The valence of F is exemplified as monovalent, but is not limited to this.

[0037] Lm (Lm is at least one selected from Cl, Br, and I) is a component that can improve stability against crystallization by coexisting with fluoride ions in glass. The content of Lm is preferably 0.1 to 20% expressed as anion %. If the content of Lm is too low, it becomes difficult to obtain the above-mentioned effects. Therefore, the lower limit of the content of Lm is preferably 0.1% or more expressed as anion %, more preferably 0.2% or more, and particularly preferably 0.3% or more. On the other hand, if the content of Lm is too high, problems such as devitrification of the glass, phase separation of the glass, and deterioration of weather resistance are likely to occur. Therefore, the upper limit is preferably 20% or less expressed as anion %, more preferably 15% or less, 10% or less, 5% or less, and particularly preferably 3% or less. There are no particular restrictions on the method of introducing Lm into glass.

[0038] Cl is a component that can significantly improve stability against crystallization when it coexists with fluoride ions in glass. The Cl content is preferably 0 to 20% in anion %. If the Cl content is too low, the above effects are difficult to achieve. Therefore, the lower limit of the Cl content is preferably 0% or more in anion %, and more preferably 0.1% or more, 0.2% or more, and particularly 0.3% or more. On the other hand, if the Cl content is too high, problems such as glass devitrification, glass phase separation, and deterioration of weather resistance are likely to occur. Therefore, the upper limit is preferably 20% or less in anion %, and more preferably 15% or less, 10% or less, 5% or less, and particularly 3% or less. Among halide ions, Cl in particular can significantly improve stability against crystallization when it coexists with fluoride ions in glass. Furthermore, the valence of Cl is exemplified by, but is not limited to, monovalent.

[0039] Br is a component that can improve stability against crystallization by coexisting with fluoride ions in glass. The Br content is preferably 0 to 20% expressed as anion %. If the Br content is too low, it becomes difficult to obtain the above-mentioned effects. Therefore, the lower limit of the Br content is preferably 0% or more expressed as anion %, and more preferably 0.1% or more, 0.2% or more, and particularly 0.3% or more. On the other hand, if the Br content is too high, problems such as devitrification of the glass, glass phase separation, and deterioration of weather resistance are likely to occur. Therefore, the upper limit is preferably 20% or less expressed as anion %, and more preferably 15% or less, 10% or less, 5% or less, and particularly 3% or less. In addition, the valence of Br is exemplified by monovalent Br, but is not limited thereto.

[0040] I is a component that can improve stability against crystallization by coexisting with fluoride ions in glass. The I content is preferably 0 to 20% expressed as anion %. If the I content is too low, it becomes difficult to obtain the above-mentioned effects. Therefore, the lower limit of the I content is preferably 0% or more expressed as anion %, and more preferably 0.1% or more, 0.2% or more, and particularly 0.3% or more. On the other hand, if the I content is too high, problems such as devitrification of the glass, glass phase separation, and deterioration of weather resistance are likely to occur. Therefore, the upper limit is preferably 20% or less expressed as anion %, and more preferably 15% or less, 10% or less, 5% or less, and particularly 3% or less. In addition, the valence of I is exemplified as monovalent, but is not limited thereto.

[0041] Y can improve the dispersibility of rare earth elements in glass. This can prevent concentration quenching even when rare earth elements are contained at high concentrations. It is also a component that can improve stability against crystallization. The Y content is preferably 0.1 to 20% in terms of cation %. If the Y content is too low, it becomes difficult to achieve the above effects. Therefore, the lower limit of the Y content is preferably 0.1% or more in terms of cation %, and is preferably 1% or more, 3% or more, 5% or more, 7% or more, 10% or more, and particularly 11% or more. On the other hand, if the Y content is too high, crystallization becomes more likely. Therefore, the upper limit of the Y content is preferably 20% or less in terms of cation %, and is preferably 15% or less, and particularly preferably 13% or less. The valence of Y is, for example, trivalent, but is not limited to this.

[0042] The halide glass of the present invention may further contain other cationic components. For example, it may contain Zr, Hf, Ga, In, and Zn. More specifically, it may contain Zr, Hf, Ga, In, and Zn in a total amount of 15% or less, 10% or less, and particularly 5% or less, expressed in cationic percentages. The valence of each ion may be, but is not limited to, divalent, trivalent, or tetravalent.

[0043] The halide glass of the present invention is preferably a so-called fluoride glass containing fluoride as a main component, although the halide glass of the present invention may contain the following optional components in addition to fluoride.

[0044] The halide glass of the present invention may contain a phosphate component. The inclusion of a phosphate component can enhance the stability of the glass. From the viewpoint of achieving the above-mentioned effects, when the phosphate component is incorporated into the glass, the P content, expressed as cation %, is preferably 30% or less, 20% or less, and particularly preferably 10% or less. The valence of P is, for example, but not limited to, pentavalent. The O content, expressed as anion %, is preferably 30% or less, 20% or less, and particularly preferably 10% or less. While there are no particular restrictions on the lower limits of each, the lower limit of the P content, expressed as cation %, is preferably 0% or more, 0.1% or more, and particularly preferably 0.5% or more. The lower limit of the O content, expressed as anion %, is preferably 0% or more, 0.1% or more, and particularly preferably 0.5% or more. The O valence is, for example, but not limited to, divalent.

[0045] The upper limit of the β-OH value of the halide glass of the present invention is preferably 2.0 / mm or less, more preferably 1.5 / mm or less, 1.0 / mm or less, 0.5 / mm or less, and particularly preferably 0.3 / mm or less. The lower limit is not particularly limited, but is preferably 0.01 / mm or more, more preferably 0.03 / mm or more, 0.05 / mm or more, and particularly preferably 0.07 / mm or more. The β-OH value indicates the amount of water in the glass, and the higher the β-OH value, the greater the water content. Furthermore, if the β-OH value in the glass is too high, the weather resistance is likely to decrease. As a result, the glass is more susceptible to deterioration over time. Furthermore, the higher the β-OH value, the more likely bubbles are to occur in the glass. When bubbles are present in the glass, excessive light scattering occurs in the bubbles, which tends to reduce the luminous efficiency.

[0046] The β-OH value can be determined by measuring the transmittance of glass using an FT-IR Frontier (manufactured by Perkin Elmer) and using the following formula: The transmittance was measured under the following conditions: scan speed: 100 μm / min, sampling pitch: 1 cm －1 The number of scans is set to 10 per measurement.

[0047] β-OH value = (1 / X) log １０ (T1 / T2) X: Glass thickness (mm) T1: Reference wave number 3846 cm -1 T2: Hydroxyl group absorption wave number 3600 cm -1 Minimum transmittance (%) in the vicinity

[0048] In the glass of the present invention, when high transmittance in the infrared region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 1200 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 81% or more, 83% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the infrared region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 1200 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that the suitable transmittance is not limited to the specific numerical ranges described above.

[0049] In the glass of the present invention, when high transmittance in the near-infrared region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 800 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the near-infrared region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 800 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0050] In the glass of the present invention, when high transmittance in the visible range is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 555 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 84% or more, 85% or more, 86% or more, 87% or more, and particularly preferably 88% or more. On the other hand, when low transmittance in the visible range is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 555 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 8% or less, 6% or less, 4% or less, 3% or less, 2% or less, and particularly preferably 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0051] In the glass of the present invention, when high transmittance is required in the UV-A ultraviolet region, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 380 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 36% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 82% or more, 83% or more, and particularly 84% or more. If the transmittance at a wavelength of 380 nm is too low, the glass will be colored yellow, making it difficult to achieve the desired colorless transparency. On the other hand, when low transmittance is required in the UV-A ultraviolet region, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 380 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0052] In the glass of the present invention, when high transmittance in the UV-B ultraviolet region is required, the lower limit of the transmittance at a thickness of 1 mm and a wavelength of 300 nm is preferably 0.1% or more, and is preferably 1% or more, 5% or more, 10% or more, 20% or more, 24% or more, 28% or more, 30% or more, 40% or more, 43% or more, 44% or more, and particularly 45% or more. On the other hand, when low transmittance in the UV-B ultraviolet region is required, the upper limit of the transmittance at a thickness of 1 mm and a wavelength of 300 nm is preferably 50% or less, and is preferably 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, 4% or less, 3% or less, 2% or less, and particularly 1% or less. Note that suitable transmittances are not limited to the specific numerical ranges described above.

[0053] The glass of the present invention preferably has a haze at a thickness of 1 mm of 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, 0.3% or less, 0.2% or less, 0.1% or less, 0.05% or less, 0.01% or less, 0.005%, and particularly preferably 0.001% or less. The haze can be measured in accordance with JIS K7136 using a haze meter (NDH 8000SP manufactured by Nippon Denshoku Industries Co., Ltd.) or the like.

[0054] The water resistance test, acid resistance test, and alkali resistance test in the present invention were evaluated by conducting tests in accordance with the Japan Optical Glass Industry Association standard JOGIS "Method for measuring the chemical durability of optical glass (powder method) 06-1999." Note that the water resistance test used pure water adjusted to a pH of 6.5 to 7.5, the acid resistance test used a 0.01 mol / L aqueous solution of nitric acid, and the alkali resistance test used a 0.01 mol / L aqueous solution of sodium hydroxide.

[0055] The mass loss in the water resistance evaluation according to JOGIS is preferably 1.0% or less, more preferably 0.5% or less, 0.1% or less, and particularly preferably 0.05% or less. A small mass loss in the water resistance evaluation means that the product is less susceptible to deterioration over time. Furthermore, the mass loss in the acid resistance evaluation according to JOGIS is preferably 2.0% or less, more preferably 1.5% or less, 1.0% or less, 0.5% or less, and particularly preferably 0.25% or less. A small mass loss in the acid resistance evaluation means that the product is less susceptible to deterioration over time. Furthermore, the mass loss in the alkali resistance evaluation according to JOGIS is preferably 2.0% or less, more preferably 1.5% or less, 1.0% or less, 0.5% or less, and particularly preferably 0.25% or less. A small mass loss in the alkali resistance evaluation means that the product is less susceptible to deterioration over time.

[0056] The weather resistance test was carried out by observing the surface after holding it at 60°C and 90% RH for 24 hours. Those that did not show any cloudiness on the surface were marked with "○", and those that showed cloudiness were marked with "×". Good results in the weather resistance test indicate that the product is less likely to deteriorate over time.

[0057] By satisfying the above conditions, the present invention can provide a halide glass that does not devitrify even when a rare earth element is introduced.

[0058] The halide glass of the present invention can be suitably used as an optical element. In other words, the optical element of the present invention is characterized by comprising the above-mentioned halide glass of the present invention. Examples of optical devices include laser oscillators, wavelength converters, and optical fibers, and the glass can be suitably used as an optical element for these devices. In particular, the glass can be suitably used as a laser medium for laser oscillators (see FIG. 3).

[0059] The shape of the halide glass of the present invention when used as an optical element will now be described. When the end face 11 of the glass is a circular rod-like shape as shown in FIG. 1 , the upper limit of the diameter of the end face 11 is preferably 100 mm or less, and more preferably 80 mm or less, 60 mm or less, 40 mm or less, 30 mm or less, 20 mm or less, and particularly preferably 10 mm or less. When the diameter of the end face 11 is less than the above upper limit, it is easy to mold a homogeneous glass and improve the yield. On the other hand, the lower limit of the diameter of the end face 11 is preferably 0.1 mm or more, and more preferably 0.5 mm or more, 1 mm or more, 3 mm or more, and particularly preferably 5 mm or more. When the diameter of the end face 11 is greater than the above lower limit, the glass of the present invention can be used as a laser medium for oscillating a large-diameter laser. Furthermore, the laser excitation density can be reduced, making it easier to avoid damage to the laser medium. While the figure shows a cylindrical shape for convenience, the shape is not limited thereto; it may be an approximately cylindrical shape, an approximately elliptical cylinder, an approximately rectangular parallelepiped, or other shapes. The schematic diagrams of the approximately cylindrical and elliptical cylindrical shapes are the same as those in Fig. 1. The schematic diagram of the approximately rectangular parallelepiped shape is shown in Fig. 2. In either case, the circle-equivalent diameter is regarded as the above-mentioned diameter value.

[0060] When the glass of the present invention is in the form of a rod, the upper limit of the length of the glass of the present invention is preferably 400 mm or less, and more preferably 350 mm or less, 300 mm or less, 250 mm or less, 200 mm or less, 150 mm or less, and particularly preferably 100 mm or less. When the length of the glass is not more than the above upper limit, it is easy to form a homogeneous glass and improve the yield. Furthermore, when used in laser applications, it is easy to ignore the effects of thermal expansion. On the other hand, the lower limit of the length of the glass is preferably 1 mm or more, and more preferably 5 mm or more, 10 mm or more, 30 mm or more, and particularly preferably 50 mm or more. When the length of the glass is not less than the above lower limit, it is easy to improve the cooling efficiency when used in laser applications, and it is easy to extend the usable period of the glass. Furthermore, since the laser optical path length can be increased, it is easy to generate a high-output laser power.

[0061] In the glass of the present invention, the upper limit of the arithmetic mean roughness (Ra) of the end face 11 is preferably 200.00 nm or less, and is preferably 100.00 nm or less, 50.00 nm or less, 25.00 nm or less, 10.00 nm or less, 5.00 nm or less, 4.00 nm or less, 3.00 nm or less, 2.00 nm or less, and particularly preferably 1.00 nm or less. When the arithmetic mean roughness of the end face 11 is below the above upper limit, incident light is less likely to be scattered when used in laser applications, and the amount of incident light entering the glass is increased, making it easier to improve the emission intensity. In addition, emitted light is less likely to be scattered, making it easier to obtain high-output laser power. The lower limit of the arithmetic mean roughness of the end face 11 is preferably 0.01 nm or more, and is preferably 0.05 nm or more, and particularly preferably 0.10 nm or more. When the arithmetic mean roughness of the end face 11 is above the above lower limit, manufacturing costs are more likely to be reduced.

[0062] In the glass of the present invention, the upper limit of the arithmetic mean roughness (Ra) of the side surface 12 is preferably 200.00 nm or less, and more preferably 100.00 nm or less, 50.00 nm or less, 10.00 nm or less, 5.00 nm or less, 1.00 nm or less, and particularly preferably 0.50 nm or less. If the arithmetic mean roughness of the side surface 12 is below the above upper limit, excitation light incident from the side surface 12 is less likely to be attenuated when used in laser applications. Furthermore, when total reflection of laser light at the side surface 12 is utilized inside a laser medium, the amount of laser light leaking outside the laser medium during total reflection can be suppressed, making it easier to obtain high-output laser power. The lower limit of the arithmetic mean roughness of the side surface 12 is preferably 0.01 nm or more, more preferably 0.05 nm or more, and particularly preferably 0.10 nm or more. If the arithmetic mean roughness of the side surface 12 is above the above lower limit, manufacturing costs are more likely to be reduced.

[0063] When the glass of the present invention is in the form of a plate, the upper limit of the arithmetic mean roughness (Ra) of its end face is preferably 100 nm or less, and more preferably 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly preferably 1 nm or less. If the arithmetic mean roughness of the end face is too large, it becomes difficult for light to enter the glass from the end face of the glass into the glass, and it becomes difficult for light to exit from the inside of the glass to the outside of the glass, making it difficult to obtain glass with the desired high transmittance. In addition, the glass is more likely to break. On the other hand, if the arithmetic mean roughness of the end face is too small, when attempting to physically support the glass at the end face of the glass, the contact area between the glass and the support becomes small, reducing frictional resistance and potentially making it difficult to reliably support the glass. Therefore, the lower limit of the arithmetic mean roughness of the edge face of the glass of the present invention is preferably 0.00001 nm or more, more preferably 0.0001 nm or more, 0.001 nm or more, 0.01 nm or more, or 0.1 nm or more.

[0064] The upper limit of the waviness of the glass of the present invention is preferably 10 μm or less, and more preferably 5 μm or less, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, 0.1 μm or less, 0.08 μm or less, 0.05 μm or less, 0.03 μm or less, 0.02 μm or less, and particularly preferably 0.01 μm or less. If the waviness is too large, a distribution of the incident angle of light onto the glass surface at a specific position is likely to occur, the amount of light scattering on the glass surface increases on average, and it becomes difficult to obtain glass with the desired high transmittance. On the other hand, the lower limit of the waviness is not particularly limited, but in reality it is 0.01 nm or more.

[0065] The upper limit of the thickness of the glass of the present invention is preferably 30 mm or less, and more preferably 20 mm or less, 10 mm or less, 9 mm or less, 8 mm or less, 7 mm or less, 6 mm or less, 5 mm or less, and particularly preferably 4 mm or less. If the glass thickness is too thick, the attenuation rate of light inside the glass increases, making it difficult to obtain glass with the desired high transmittance. On the other hand, the lower limit of the thickness of the glass of the present invention is preferably 0.1 mm or more, more preferably 0.5 mm or more, and particularly preferably 1 mm or more. If the glass thickness is too thin, sufficient laser amplification cannot be achieved when used in laser applications. Furthermore, there is a concern that the glass may deform under its own weight when the area is large.

[0066] The upper limit of the difference between the maximum thickness and the minimum thickness of the glass of the present invention is preferably 50 μm or less, and is preferably 25 μm or less, 10 μm or less, 5 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, 100 nm or less, 50 nm or less, 25 nm or less, 15 nm or less, 10 nm or less, 9 nm or less, 8 nm or less, 7 nm or less, 6 nm or less, 5 nm or less, 4 nm or less, 3 nm or less, 2 nm or less, and particularly preferably 1 nm or less. If the difference between the maximum thickness and the minimum thickness is too large, the angle of incidence of light incident from either the front or back surface will differ from the angle of emergence when emitted from the other surface, which tends to result in undesirable light scattering and a glaring appearance.

[0067] The arithmetic mean roughness (Ra) of the main surface and edge surface of the glass can be measured by a method conforming to JIS B0601:2001. Furthermore, waviness can be measured using a stylus-type surface profiler in accordance with SEMI STD D15-1296 "Method for measuring surface waviness of FPD glass substrates." Thickness can be measured using common devices such as digital calipers or a point-contact roughness meter.

[0068] When the glass of the present invention is in the form of a fiber, its total length is preferably 500 m or less, and more preferably 300 m or less, 100 m or less, 50 m or less, 10 m or less, and particularly preferably 1 m or less. When the total length is less than the above upper limit, it is easy to form it into a fiber, and the yield is likely to be improved. Furthermore, when it is used as the core or cladding of an optical fiber, the transmission loss is likely to be small. On the other hand, the lower limit is preferably 1 cm or more, and more preferably 5 cm or more, 10 cm or more, 30 cm or more, and particularly 50 cm or more. When the total length is greater than the above lower limit, it is possible to obtain wavelength-converted light of sufficient intensity for excitation light when it is used as the core or cladding of an optical fiber. When the glass of the present invention is used as the core of an optical fiber, the cladding material is preferably glass or resin. Furthermore, when the glass of the present invention is used as the cladding of an optical fiber, the core material is preferably glass or resin. The cladding material when the glass of the present invention is used as the core of an optical fiber, and the core material when the glass of the present invention is used as the cladding of an optical fiber, are not limited to the above-mentioned glasses and resins.

[0069] When the glass of the present invention is used as an optical element, the shape thereof is not limited to the rod, plate, and fiber shapes mentioned above.

[0070] An optical device using the halide glass of the present invention as an optical element will now be described. FIG. 3 is a schematic diagram showing an example of the configuration of a laser oscillator using the glass of the present invention. The laser oscillator 2 comprises an excitation light source 20, resonators 22 and 24, and a laser medium 26. The laser medium 26, made of the glass of this embodiment, is disposed between the resonators 22 and 24, which are arranged parallel to each other. The resonator 22 is designed to transmit excitation light L1 and totally reflect laser light L2, while the resonator 24 is designed to transmit a portion of the laser light L2. The laser medium 26 is made of the glass of this embodiment, with the surfaces parallel to the resonators 22 and 24 mirror-polished. The laser medium 26 is excited by excitation light L1 emitted by the excitation light source 20. The laser light L2 thus generated is amplified by traveling back and forth between the resonators 22 and 24 while passing through the laser medium 26. A portion of the laser light L2 emitted from the laser medium 26 is extracted to the outside through the resonator 24. The excitation light source 20 may be, for example, a solid-state laser or a semiconductor laser.

[0071] The optical elements and optical devices using the glass of the present invention are not limited to the laser medium, optical fiber, and laser oscillator described above.

[0072] The halide glass of the present invention can be produced, for example, as follows.

[0073] First, raw materials are weighed to obtain a raw material batch having the desired composition. Then, the raw material batch is placed in a crucible. The crucible may be a platinum crucible, a gold crucible, a glassy carbon crucible, or the like.

[0074] The raw material is, for example, AlF ３ , ScF ３ , MgF ２ , CaF ２ , SrF ２ , BaF ２ , CrF ３ , CeF ３ , NdF ３ , YbF ３ , ErF ３ , PrF ３, SmF ３ , EuF ３ , TbF ３ , DyF ３ , HoF ３ , TmF ３ , Y.F. ３ , ZrF ４ , HfF ４ , GaF ３ , InF ３ , ZnF ２ , Al(PO ３ ) ３ , Mg(PO ３ ) ２ , Ca(PO ３ ) ２ , Sr(PO ３ ) ２ , Ba(PO ３ ) ２ , P ２ O ５ , KPF ６ , AlCl ３ , YCl ３ , YbCl ３ , MgCl ２ , CaCl ２ , SrCl ２ , and BaCl ２ can be used, but is not limited to these.

[0075] Next, the raw material batch is melted at approximately 900°C to 1100°C. The melting time can be, for example, 1 to 2 hours. The melt is then rapidly cooled and gradually strained near the glass transition temperature to obtain a halide glass.

[0076] The present invention will be described below based on examples, but the present invention is not limited to these examples.

[0077] Tables 1 to 16 show Examples 1 to 103 of the present invention and comparative examples.

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094] The samples were prepared by the following procedure. First, raw materials were weighed to obtain raw material batches with the compositions shown in Tables 1 to 16. Next, the raw material batches were placed in a crucible and melted at 900°C to 1100°C, and the melt was then rapidly cooled to obtain the samples.

[0095] Whether or not vitrification had occurred was judged visually. If devitrification had not occurred, it was judged as having vitrified and was marked with "O", and if devitrification had occurred, it was judged as not having vitrified and was marked with "X".

[0096] Fluorescence was evaluated by irradiating light of the excitation wavelength of the rare earth element contained in the glass of each example with the glass and determining whether or not fluorescence was observed. Those that exhibited fluorescence were evaluated as "Good" and those that did not exhibit fluorescence were evaluated as "Poor." The excitation light and luminescence were measured using a fluorescence spectrophotometer. The results are shown in Tables 1 to 16.

[0097] REFERENCE SIGNS LIST 1... glass 11... end face 12... side face 2... laser oscillator 20... excitation light source 22... resonator 24... resonator 26... laser medium

Claims

1. A halide glass containing, in cationic percentages, 11 to 60% Al, 0.1 to 20% Sc, 10 to 88.7% Mg + Ca + Sr + Ba, and 0.01 to 20% Ln (Ln is at least one element selected from Cr, Ce, Nd, Yb, Er, Pr, Sm, Eu, Tb, Dy, Ho, and Tm), and, in anionic percentages, 70 to 100% F.

2. The halide glass according to claim 1, which contains, in anion % representation, 70 to 99.9% F and 0.1 to 20% Lm (Lm is at least one element selected from Cl, Br and I).

3. The halide glass according to claim 1 or 2, containing, in cationic percentages, 0 to 30% Mg, 0 to 30% Ca, 0 to 30% Sr, and 0 to 20% Ba.

4. The halide glass according to claim 1 or 2, which contains, in cationic percentage, 0.1 to 20% Y.

5. An optical element made of the halide glass according to claim 1 or 2.

6. An optical device using the optical element according to claim 5.

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