JP2004067460A - Glass composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass composition for a wave-length division multiplexing (WDM) optical filter, which has good processing property as glass and has excellent propagation characteristics of light, as a WDM optical filter material which is used for the WDM of light in the field of optical communication and which transmits only light having specific wavelengths. <P>SOLUTION: The glass composition for the WDM optical filter contains, by weight, 50-60% SiO<SB>2</SB>, 1-10% Al<SB>2</SB>O<SB>3</SB>, 0-4% ZrO<SB>2</SB>, 0-5% Li<SB>2</SB>O, 10-25% Na<SB>2</SB>O, 1-20% K<SB>2</SB>O, 0-5% MgO, 0-10% CaO, 0-10% BaO, and 1-6% ZnO, with the proviso that the total content of Li<SB>2</SB>O, Na<SB>2</SB>O, and K<SB>2</SB>O is 20-30%, and the total content of MgO, CaO, and BaO is 2-20%. Further, the glass composition is characterized in that the mean coefficient of thermal expansion in a temperature range of from 50 to 150°C is 115-130×10<SP>-7</SP>/°C, the Young's modulus is 65-80 GPa, density is ≤2.7 g/cm<SP>3</SP>, and a weight loss in waterproof test comprising immersing a sample in distilled water with temperature of 95°C for 40 h is ≤0.75 mg/cm<SP>2</SP>. <P>COPYRIGHT: (C)2004,JPO

Description

【００３８】
表１は、本発明のＷＤＭ光フィルターに関わり、その組成物および各組成物のガラス組成が、重量％で表して、実施例１〜７のガラスの組成物、重量％で表したそのガラス組成、５０〜１５０℃における平均熱膨張係数（α_{５０−１５０}）、ヤング率、密度および９５℃の蒸留水に４０時間浸漬した場合の重量減少量（△Ｍ）を示したものである。また、代表的なガラスの内部透過率曲線（板厚１ｍｍ）を図１に示す。この例は実施例１の場合であるが、他の例もほぼ同様の傾向を示した。
【００３９】
【表２】

【００４０】
表２は、前記組成および各含有物のガラス組成の範囲から外れた比較例１〜９のガラスの組成物、その重量％で表したガラス組成、５０〜１５０℃における平均熱膨張係数（α_{５０−１５０}）、ヤング率、密度および耐水性（△Ｍ）の評価結果を示したものである。
【００４１】
表１に示すように、　本発明のＷＤＭ光フィルター用ガラスの組成物を用い、各組成物のガラス組成を前記範囲とした実施例１〜７のガラスは、５０〜１５０℃における平均熱膨張係数が１１５〜１３０×１０^−７／℃、ヤング率が６５〜８０ＧＰａ、密度が２．７ｇ／ｃｍ^３以下、耐水性試験時の重量減少量が０．７５ｍｇ／ｃｍ^２以下であることを全て満足した。
【００４２】
なお、図１に示した内部透過率曲線における光通信波長域（１３００ｎｍ以上）の透過率および熱膨張係数等の物性を損なわない範囲であれば、ガラスに着色成分を導入することができる。すなわち、ＴｉＯ_２、ＣｅＯ_２、Ｅｕ_２Ｏ_３、Ｃｒ_２Ｏ_３、Ｍｎ_３Ｏ_４などの酸化物着色成分を５ｗｔ％までの範囲で導入することができる。また、清澄剤として各種硫酸塩、硝酸塩の他、Ｓｂ_２Ｏ_３、Ａｓ_２Ｏ_３などを前記物性を損なわない範囲で使用することができる。
【００４３】
それに比較して、表２に示すように、各組成物のガラス組成が前記組成から外れた比較例１〜９のガラスは、５０〜１５０℃における平均熱膨張係数が１１５〜１３０×１０^−７／℃、ヤング率が６５〜８０ＧＰａ、密度が２．７ｇ／ｃｍ^３以下、耐水性試験時の重量減少量が０．７５ｍｇ／ｃｍ^２以下であることについて満足しなかった。ここでは明記しなかったが、ガラス化しなかった場合には当然ながら評価はＮＧとなる。
【００４４】
【発明の効果】
本発明のＷＤＭ光フィルター用ガラスは、前述のガラス組成およびガラス物性の範囲に限定することで、満足できる性能を示した。また、結晶化ガラスではないので、長時間の加熱処理が必要なく価格が安く抑えられた。さらに、必要な熱膨張係数が容易に得られたことで多層膜成膜時に発生する応力による基板の反りを改善するとともに、ヤング率、密度を適切化することでチップの加工性と基板の機械的強度を両立し、さらに耐水性にも優れたガラスである。
【図面の簡単な説明】
【図１】実施例１の板厚１ｍｍにおける内部透過率曲線。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a glass composition for a WDM optical filter used as a WDM optical filter material that passes only a specific wavelength range and is used for wavelength division multiplexing (WDM) of light in the field of optical communication. About.
[0002]
[Prior art]
Examples of what is called an optical filter include a filter that cuts a specific wavelength, a filter that transmits a specific wavelength, and a filter that reduces transmission of light. The former optical filter includes a band-pass filter that transmits only specific wavelengths, a notch-pass filter that cuts only specific wavelengths, a low-pass filter that transmits only wavelengths shorter than the specific wavelength, and a Also, there is a high-pass filter that transmits only the wave on the long wavelength side. An ND filter or the like is representative of the latter optical filter.
[0003]
In wavelength-division multiplexing optical communication, light having slightly different wavelengths is multiplexed, or conversely, demultiplexed to selectively extract light of a specific wavelength from light containing a plurality of wavelength components. A filter is used.
[0004]
Such a narrow band-pass filter accompanying the development of the wavelength division multiplexing WDM system is called a WDM optical filter, and is disclosed in Japanese Patent Application Laid-Open No. 10-339825 and Japanese Patent Application Laid-Open No. 10-512975. Is obtained by forming a dielectric multilayer film made of SiO ₂ , TiO ₂ , Ta ₂ O ₅ or the like on a quartz substrate.
[0005]
Wavelength Division Multiplexing With the increase in the accuracy of WDM systems, it is required to reduce the bandwidth of the transmission wavelength of WDM optical filters in order to perform higher-density wavelength-division multiplexing optical communication than before. When the band width of the transmission wavelength is narrowed, the allowable range of the shift of the center wavelength of the band is also narrowed, so that the shift of the wavelength center due to a slight temperature fluctuation also has a great effect. For this reason, it is required to avoid a change in the refractive index due to a change in the operating temperature of the WDM optical filter member and to make the temperature shift of the wavelength close to zero.
[0006]
It is known that the temperature shift depends on the thermal expansion coefficients of the glass and the dielectric multilayer film. As a method of bringing the temperature shift closer to zero, glass taking into account the difference between the thermal expansion coefficient of the glass and the thermal expansion coefficient of the dielectric multilayer film is disclosed in JP-A-2001-89184, JP-A-2001-48584, and JP-A-2001-2001. -66425 and the like.
[0007]
[Problems to be solved by the invention]
However, the glass of the glass composition described in JP-A-2001-66425 and JP-A-2001-89184 is brittle, and when dicing with a diamond cutter and cutting into chips, the end portion is cut off, resulting in poor yield. There was a problem.
[0008]
In Japanese Patent Application Laid-Open No. 2001-48584, glass ceramics, that is, crystallized glass is used. However, a crystallization step is required, and a long-time heat treatment is required at that time. There was a problem of becoming.
[0009]
[Means for Solving the Problems]
In order to solve such a problem, the present inventor has a physical property value suitable for a WDM optical filter, does not require a long-time heat treatment at a high temperature at the time of glass production, after the glass The present inventors have conducted intensive studies on a glass having good workability and good light propagation characteristics, and completed the glass for a WDM optical filter of the present invention.
[0010]
That is, the present invention relates to a glass for a WDM optical filter which forms an optical multilayer film for a band pass on the surface, and the glass composition is represented by weight% and is SiO ₂ , 50 to 60%, Al ₂ O ₃ , _{1~10%, ZrO 2, 0~4%} , Li 2 O, 0~5%, Na 2 O, 10~25%, K 2 O, 1~20%, MgO, 0~5%, CaO, 0 _10%, a _{BaO, 0~10%, ZnO, 1~6} %, Li 2 O + Na 2 O + K 2 O, 20~30%, MgO + CaO + BaO, WDM optical filter glass composition in the range of 2-20%.
[0011]
Furthermore, the present invention is the above-mentioned glass for a WDM optical filter, which has an average thermal expansion coefficient at 50 to 150 ° C. of 115 to 130 × 10 ⁻⁷ / ° C., a Young's modulus of 65 to 80 GPa or less, and a density of 2.7 g. / cm ³ or less, a glass composition for a WDM optical filter, wherein the weight reduction is 0.75 mg / cm ² or less in the water resistance test of immersing for 40 hours in 95 ° C. distilled water.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
It is known that an optimum range exists for the thermal expansion coefficient of the glass for a WDM optical filter. That is, when the thermal expansion coefficient is small, sufficient compressive stress cannot be applied to the optical multilayer film, and the temperature shift of the center wavelength of the filter increases in the positive direction. If the coefficient of thermal expansion is large, the temperature shift becomes large in the negative direction, causing problems such as peeling of the multilayer film or destruction of the substrate.
[0013]
The present inventor produced a SiO ₂ / Ta ₂ O ₅ -based three-cavity bandpass filter by a vapor deposition method and confirmed that the preferable average thermal expansion coefficient at 50 to 150 ° C. was 115 to 130 × 10 ⁻⁷ /. ° C. Within this range, an appropriate compressive stress can be applied to the multilayer film, and the temperature dependence of the filter characteristics can be made as close to zero as possible depending on the film formation method. Therefore, the preferable average thermal expansion coefficient of the glass for a WDM optical filter of the present invention is 115 to 130 × 10 ⁻⁷ / ° C. at 50 to 150 ° C. More preferably, it is 120 to 125 × 10 ⁻⁷ / ° C.
[0014]
The Young's modulus is closely related to the so-called strength, and generally, as the Young's modulus increases, the strength of the material tends to increase. The present inventor performed dicing processing on a plurality of substrates having different Young's moduli actually formed with a multilayer film under the same conditions, and evaluated the degree of chipping of the obtained chip end portion. If the Young's modulus was 80 GPa or less, It has been found that chipping of glass at the time of forming a multilayer film can be suppressed within an allowable range. Further, when it is 65 GPa or more, it has been found that the substrate does not break during the grinding and dicing processing after the film formation, and the mechanical strength of the glass is sufficient. Therefore, the preferable Young's modulus of the glass for a WDM optical filter of the present invention is 65 to 80 GPa at the working temperature during cutting and dicing. More preferably, it is 70 to 75 GPa.
[0015]
Regarding the density, if the glass type is the same, the glass tends to be brittle as the density increases. Therefore, the preferred density of the glass for a WDM optical filter of the present invention is 2.7 g / cm ³ or less at the working temperature during cutting.
[0016]
Water resistance is closely related to glass polishing. Glass polishing is performed competitively: mechanical polishing for mechanically removing the surface layer and chemical polishing for chemically dissolving the surface layer. If the water resistance is extremely poor, chemical polishing proceeds too much to obtain a smooth surface, and furthermore, the surface after polishing becomes burnt. Therefore, the preferable water resistance of the glass for a WDM optical filter of the present invention is 0.75 mg / cm ² or less in terms of weight loss in a water resistance test in which the glass is immersed in distilled water at 95 ° C. for 40 hours.
[0017]
In the present invention, the inventor used SiO ₂ , Al ₂ O ₃ , Na ₂ O, K ₂ O, and ZnO as essential components, and ZrO ₂ , MgO, CaO, BaO, and Li ₂ O as additional components. The glass is produced while adjusting the glass composition of each component. The average thermal expansion coefficient at 50 to 150 ° C. is 115 to 130 × 10 ⁻⁷ / ° C., the Young's modulus at the working temperature is 65 to 80 GPa, and the density is A glass composition for a WDM optical filter having a weight loss of 0.75 mg / cm ² or less in a water resistance test of immersion in distilled water at a temperature of 2.7 g / cm ³ or less and 95 ° C. for 40 hours to complete the present invention. Reached.
[0018]
The role of each component and the glass composition will be described in detail below.
[0019]
SiO ₂ is an essential component of the glass for a WDM optical filter of the present invention, which is introduced into glass to form a glass skeleton. If the glass composition of SiO ₂ is less than 50 wt%, the glass state becomes unstable, devitrification and the like are likely to occur, and the glass does not become stable. Further, the density becomes too large due to additional components such as alkaline earth components to be introduced instead of SiO ₂ . On the other hand, if it exceeds 60% by weight, the coefficient of thermal expansion becomes too low.
[0020]
Al ₂ O ₃ has the effect of stabilizing the glass state, and is essential for the glass for a WDM optical filter of the present invention, which is introduced into the glass to adjust the thermal expansion coefficient and Young's modulus by adjusting the glass composition. Component. However, if the glass composition is less than 1 wt%, the effect cannot be expected. On the other hand, if it exceeds 10 wt%, the thermal expansion coefficient becomes too low and the Young's modulus becomes too large.
[0021]
ZrO ₂ is an additional component of the glass for a WDM optical filter of the present invention, which is effective for stabilizing the glass state when introduced in a small amount and is introduced into the glass to improve the water resistance of the glass. . However, when the glass composition exceeds 4% by weight, the tendency of devitrification of the glass is increased, and the coefficient of thermal expansion is too small.
[0022]
Li ₂ O is an additional component of the glass for a WDM optical filter of the present invention, which is introduced for adjusting the coefficient of thermal expansion and the Young's modulus. If it exceeds 5 wt%, the glass becomes unstable, and devitrification and the like are likely to occur. A more preferred glass composition range of Li ₂ O is a 0 to 3wt%.
[0023]
Na ₂ O is an essential component of the glass for a WDM optical filter of the present invention, which is introduced into glass to increase the coefficient of thermal expansion. If the glass composition is less than 10% by weight, the effect of increasing the thermal expansion coefficient of the glass cannot be obtained. On the other hand, if the content exceeds 25 wt%, the glass state becomes unstable, the glass tends to be devitrified, the water resistance is impaired, and burns easily occur. Therefore, the preferable glass composition range of Na ₂ O is 10 to 25 wt%.
[0024]
K ₂ O is an essential component of the glass for a WDM optical filter of the present invention, which is introduced into glass to increase the coefficient of thermal expansion. If the glass composition is less than 1% by weight, the effect cannot be expected. On the other hand, if it exceeds 20 wt%, the water resistance is impaired. Therefore, a preferable glass composition range of K ₂ O is 1 to 20 wt%.
[0025]
MgO is an additional component of the glass for a WDM optical filter of the present invention, which is introduced into the glass for adjusting the coefficient of thermal expansion and the Young's modulus. If it exceeds 5 wt%, the expansion coefficient becomes too small.
[0026]
CaO is an additional component of the glass for a WDM optical filter of the present invention, which is introduced into the glass for adjusting the coefficient of thermal expansion and the Young's modulus. If it exceeds 10% by weight, the devitrification tendency becomes strong and the expansion coefficient becomes too small.
[0027]
BaO is an additional component of the glass for a WDM optical filter of the present invention, which is introduced into the glass for adjusting the coefficient of thermal expansion and the Young's modulus. If it exceeds 10 wt%, the density becomes too large and the water resistance of the glass decreases.
[0028]
ZnO is an essential component of the glass for a WDM optical filter of the present invention, which stabilizes the glass with a small content and is introduced into the glass for adjusting the coefficient of thermal expansion and the Young's modulus. If it is less than 1 wt%, the effect cannot be expected. On the other hand, if it exceeds 6% by weight, the water resistance of the glass decreases.
[0029]
Li the total amount of _{2 O + Na 2 O + K} 2 O has an effect on the stability of the coefficient of expansion, water resistance and glass. If it is less than 20%, the expansion coefficient becomes too small. If it exceeds 30%, the glass becomes unstable and the water resistance becomes too low. In some cases, it does not become glass. _Thus, the total amount of _{Li 2 O + Na 2 O +} K 2 O is in the range of 20-30%.
[0030]
The total amount of MgO + CaO + BaO affects the density and the water resistance and is introduced for its adjustment. If it is less than 2%, the effect cannot be obtained. If it exceeds 20%, the density becomes too large, and the water resistance also decreases.
[0031]
【Example】
Hereinafter, the present invention will be described with reference to examples. Using the oxides, carbonates, nitrates, etc. corresponding to the raw materials of the respective components of the glass, the resulting glass has the composition described in Examples 1 to 7 of Table 1 and Comparative Examples 1 to 9 of Table 2. Were weighed and mixed at a predetermined ratio.
[0032]
The mixed raw material was put in a platinum crucible containing 2000 ml of volume and 10 wt% of rhodium, and was melted for 5 hours in an electric furnace heated to 1400 ° C., after which fine bubbles contained in the molten glass were removed. After cooling in a furnace to an appropriate temperature to remove it, pour it into a graphite mold, put it in an electric furnace previously held near the glass transition point, hold it for 2 hours, and then cool it to room temperature. A glass block having a thickness of 30 mm and a size of 200 mm x 300 mm was obtained.
[0033]
Next, the glass block was sliced thinly, ground into a cylindrical shape, further polished on both surfaces, and Ta ₂ O ₅ and SiO ₂ were alternately deposited on one polished surface to obtain a dielectric multilayer film. Examples of a method for producing the dielectric multilayer film and the antireflection film include an RF ion plating method, a magnetron sputtering method, a plasma ion plating method, and a vapor deposition method. Thereafter, grinding and polishing were performed from the side where the film was not formed to a thickness of 1 mm, and an antireflection film was formed on the polished surface opposite to the multilayer film.
[0034]
Next, while rotating a diamond cutter in which diamond powder is adhered to a metal disk, the glass substrate on which the dielectric multilayer film is formed is applied from the non-film-forming surface side by a so-called dicing process, so that the thickness, 1 mm, size, A 0.5 mm square chip was cut out.
[0035]
The glass thus produced was measured for its coefficient of thermal expansion, Young's modulus, density and water resistance. The coefficient of thermal expansion was measured by a differential thermal dilatometer using silica glass as a standard sample in a temperature range of 50 ° C. to 150 ° C. The Young's modulus was measured at room temperature by an ultrasonic pulse method (sing-around method) using a 5 MHz transducer. The density was measured by the Archimedes method using distilled water as an immersion liquid. The water resistance was evaluated by using a glass polished to 20 × 50 × 2 mm ^t as a sample and determining the weight loss when immersed in 95 ° C. distilled water for 40 hours. The test conditions for the water resistance conform to the concepts of JISR3502 and JOGIS06-99, and are used, for example, for evaluating display substrates.
[0036]
FIG. 1 shows a typical internal transmittance curve (plate thickness: 1 mm) of the glass shown in Table 1. The transmittance was measured using a self-recording spectrophotometer (U4000, manufactured by Hitachi, Ltd.), and the internal transmittance was determined according to the Japan Optical Glass Industry Association Standard (JOGIS17-82). It was confirmed that the internal transmittance at a plate thickness of 1 mm was 99% or more in a region of 1300 nm or more, confirming that the glass of the present system was suitable for a WDM filter.
[0037]
[Table 1]

[0038]
Table 1 relates to the WDM optical filter of the present invention, wherein the compositions and the glass composition of each composition are represented by weight%, the compositions of the glasses of Examples 1 to 7, and the glass composition represented by weight%. It shows the average thermal expansion coefficient (α _50-150 ) at 50 to 150 ° C., the Young's modulus, the density, and the weight loss (ΔM) when immersed in 95 ° C. distilled water for 40 hours. FIG. 1 shows an internal transmittance curve (plate thickness: 1 mm) of a typical glass. This example is the case of the first embodiment, but the other examples showed almost the same tendency.
[0039]
[Table 2]

[0040]
Table 2 shows the compositions of the glasses of Comparative Examples 1 to 9, which were out of the ranges of the glass compositions of the above-mentioned compositions and the respective components, the glass compositions expressed in terms of% by weight, and the average thermal expansion coefficient (α _{50) at 50 to} 150 ° C. _-150 ), evaluation results of Young's modulus, density and water resistance (ΔM).
[0041]
As shown in Table 1, using the glass composition for a WDM optical filter of the present invention, the glasses of Examples 1 to 7 in which the glass composition of each composition was in the above range, the average thermal expansion coefficient at 50 to 150 ° C. Is 115-130 × 10 ⁻⁷ / ° C., the Young's modulus is 65-80 GPa, the density is 2.7 g / cm ³ or less, and the weight loss during the water resistance test is 0.75 mg / cm ² or less. did.
[0042]
It should be noted that a coloring component can be introduced into glass as long as physical properties such as transmittance and thermal expansion coefficient in the optical communication wavelength range (1300 nm or more) in the internal transmittance curve shown in FIG. 1 are not impaired. That is, oxide coloring components such as TiO ₂ , CeO ₂ , Eu ₂ O ₃ , Cr ₂ O ₃ , and Mn ₃ O ₄ can be introduced in a range of up to 5 wt%. Sb ₂ O ₃ , As ₂ O _{3, and the} like can be used as a fining agent in addition to various sulfates and nitrates as long as the physical properties are not impaired.
[0043]
In comparison, as shown in Table 2, the glasses of Comparative Examples 1 to 9 in which the glass composition of each composition deviated from the above-described compositions had an average coefficient of thermal expansion at 50 to 150 ° C. of 115 to 130 × 10 ^−7. / C, the Young's modulus was 65 to 80 GPa, the density was 2.7 g / cm ³ or less, and the weight loss during the water resistance test was 0.75 mg / cm ² or less. Although not specified here, when the glass is not vitrified, the evaluation is naturally NG.
[0044]
【The invention's effect】
The glass for a WDM optical filter of the present invention exhibited satisfactory performance by being limited to the above-mentioned ranges of glass composition and glass physical properties. In addition, since it is not crystallized glass, a long-time heat treatment is not required and the price is kept low. Furthermore, the required coefficient of thermal expansion was easily obtained, thereby improving the warpage of the substrate due to the stress generated during the formation of the multilayer film. It is a glass that has both good mechanical strength and excellent water resistance.
[Brief description of the drawings]
FIG. 1 is an internal transmittance curve of Example 1 at a plate thickness of 1 mm.

Claims (3)

A glass for WDM optical filter which forms a band-pass optical multilayer film on the surface, expressed in terms of weight%, the glass _{composition, SiO 2, 50~60%, Al} 2 O 3, 1~10%, ZrO _{2, 0~4%, Li 2 O} , 0~3%, Na 2 O, 10~25%, K 2 O, 1~20%, MgO, 0~5%, CaO, 0~10%, BaO, _{0~10%, ZnO, 1~6%,} Li 2 O + Na 2 O + K 2 O, 20~30%, MgO + CaO + BaO, WDM optical filter glass composition characterized by 2 to 20%. The glass for a WDM optical filter according to claim 1, wherein the average thermal expansion coefficient at 50 to 150 ° C. is 115 to 130 × 10 ⁻⁷ / ° C., the Young's modulus is 65 to 80 GPa, and the density is 2.7 g / cm ^3. A glass composition for a WDM optical filter, comprising: 2. The glass for a WDM optical filter according to claim 1, wherein a weight loss in a water resistance test in which the glass is immersed in distilled water at 95 ° C. for 40 hours is 0.75 mg / cm ² or less. Glass composition.

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