JP2004029581A - Ferrule and its processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a ferrule 1 showing excellent durability in a high-temperature atmosphere where moisture exists. <P>SOLUTION: In a ferrule 1 where a through-hole 1a for housing an optical fiber 30 is provided in the center of a cylindrical zirconia sintered body 100, a rhombohedral phase is formed in the range of at least 50 μm depth from an edge surface 1d in the sintered body 100. <P>COPYRIGHT: (C)2004,JPO

Description

【００６５】
以上より、ダイヤモンド砥石の粒径が８μｍ以下では菱面体晶相の表面からの深さが５０μｍ未満であり、算術平均表面粗さ（Ｒａ）が０．０１μｍ未満であり、曲率半径の変動値は１ｍｍを大きく超えており、熱劣化が大きいことがわかる。これに対して本発明のダイヤモンド砥石の粒径が９μｍ以上では菱面体晶相の表面からの深さが５０μｍ以上であり、算術平均表面粗さ（Ｒａ）が０．０１μｍ以上であり、しかも曲率半径の変動値が１ｍｍ以下となり、熱劣化が大幅に改善することができた。
【００６６】
【発明の効果】
以上のように本発明によれば、円筒形状に形成したジルコニア焼結体の中心に光ファイバの素線を収納するための貫通孔が形成されたフェルールにおいて、前記焼成体の先端面から少なくとも５０μｍ、最大で８００μｍの深さの範囲に菱面体晶相が形成されているので、水分の存在する高温雰囲気中での耐久性に優れたフェルールを得ることができる。
【図面の簡単な説明】
【図１】本発明のフェルールを示す断面図である。
【図２】本発明のフェルールを用いた光コネクタを示す断面図である。
【図３】本発明のフェルールを用いた光ファイバ固定具を示す断面図である。
【図４】本発明のフェルールの先端面のＸ線回折図である。
【図５】本発明の菱面体晶相の格子模型を示す図である。
【図６】本発明のフェルールの加工方法を示す図である。
【図７】本発明のフェルールの加工方法を示す図である。
【符号の説明】
１：フェルール
１ａ：貫通孔
１ｂ：円錐部
１ｃ：外周部
１ｄ：先端面
１ｅ：面取部
２：支持体
３：光ファイバ
４：接着剤
５：スリーブ
２１：ジルコニウム
２２：酸素
３０：素線
１１１：外周面
１１２：凹部
１１３：砥石
１１５：カップ砥石
１１６：砥石[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ferrule used for optical communication and a method for processing the ferrule.
[0002]
[Prior art]
In recent years, with an increase in the amount of information in communication, optical communication using an optical fiber has been used. In this optical communication, an optical connector using an optical fiber fixture is used for connecting optical fibers or connecting optical fibers to various optical elements.
[0003]
This optical fiber fixture is shown in FIGS. Here, FIG. 2 is a sectional view showing an optical fiber fixture using the ferrule of the present invention, and FIG. 3 is a sectional view showing an optical connector using the ferrule of the present invention. As shown in the figure, an optical fiber fixture 10 inserts a wire 30 of an optical fiber 3 into a through hole 1 a formed in a cylindrical fired body of a ferrule 1, and attaches an end of the ferrule 1 to a support member 2 with an adhesive 4. It is configured to be held and fixed via Next, as shown in FIG. 3, for connection between the optical fibers 3, two optical fiber fixtures 10, 10 having the optical fibers 3 are used, and the ferrules 1 are respectively attached to both ends of a sleeve 5 formed of a cylindrical body. The ferrules 1 are inserted into the sleeve 5 and processed into a convex spherical shape inside the sleeve 5, and the tip surfaces 1d of the ferrules 1 are brought into contact with each other and connected.
[0004]
Various materials such as ceramics, metal, plastic, and glass have been experimentally manufactured as the material of the ferrule 1, but most are now made of ceramics. The reason is that ceramics have high processing accuracy, so that the tolerance of the inner diameter and outer diameter can be made as high as 1 μm or less, and that the ceramics have a low friction coefficient, so that the optical fiber 30 can be inserted easily and the rigidity can be improved. Is high and has a low coefficient of thermal expansion, so that it is stable against external stress and temperature change and has excellent corrosion resistance.
[0005]
Furthermore, even when ceramics are used as the material, most of the materials have recently been replaced with zirconia from alumina. Since this zirconia sintered body has a Young's modulus as low as about half that of alumina, when the tip surfaces 1d of the two ferrules come into contact with each other, it is possible to increase the adhesion with a small load by the spring of the optical connector, and Since the strength and the toughness are high, the reliability can be improved (see Japanese Patent Publication No. 8-30775).
[0006]
As zirconia sintered body for use in the optical ferrule 1, the _Y 2 _{O 3} of about 2.5 to 3.5 mol% as a stabilizer ZrO ₂ as a main component (about 4.5-6.2 wt%) A partially stabilized zirconia sintered body mainly composed of a tetragonal crystal phase having an average crystal grain size of 0.4 to 0.6 μm formed by molding and firing the contained raw material has been proposed (JP-A-6-337327). Reference).
[0007]
In addition, a raw material containing ZrO ₂ as a main component and Y ₂ O ₃ as a stabilizer and 0.2 to 0.3% by weight of Al ₂ O ₃ added to the raw material is molded and fired to form a tetragonal crystal phase. A partially stabilized zirconia for ferrule 1 mainly composed of zirconia has been proposed (see JP-A-10-260336).
[0008]
Furthermore, in the zirconia sintered body used for the ferrule 1 containing ZrO ₂ as a main component and containing Y ₂ O ₃ as a stabilizer, the concentration of Y ₂ O ₃ in the tetragonal phase was maintained at 3.0 mol% or more. Partially stabilized zirconia has been proposed (Journal of the Ceramic).
Society of Japan, September 1999).
[0009]
In the case where zirconia of any of the above compositions is used, when the tip surfaces 1d of a pair of ferrules are brought into contact with each other as an optical connector, the ferrule 1 is connected to the tip surface 1d by the spring pressure of the optical connector without any gap. The tip surface 1d is previously made into a spherical shape by grinding, and then the optical fiber 3 is inserted into the through hole 1a and fixed with the adhesive 4, and then the tip surface 1d is finish-polished together with the tip surface of the optical fiber 4. The optical fiber fixture 10 was used.
[0010]
However, in order to minimize the polishing amount and the polishing time during the final polishing, the arithmetic mean surface roughness (Ra) of the surface portion of the tip surface is generally less than 0.01 μm.
[0011]
[Problems to be solved by the invention]
However, in any of the conventional examples described above, the ferrule 1 made of a partially stabilized zirconia sintered body containing Y ₂ O ₂ has a monoclinic crystal when exposed to a high-temperature atmosphere in which moisture exists. There is a problem that properties such as strength and toughness are deteriorated due to phase transformation into crystals.
[0012]
In order to solve this problem, it has been proposed to form a rhombohedral phase generated by phase transformation from the cubic and tetragonal structures on the tip surface of the cylindrical zirconia fired body constituting the ferrule 1.
[0013]
However, conventionally, the thickness of the rhombohedral phase is formed less than 50 μm by setting the arithmetic average roughness (Ra) of the tip surface 1 d of the ferrule 1 before bonding and fixing the optical fiber 3 to less than 0.01 μm. Instead, the rhombohedral phase was completely removed in the final polishing after the optical fiber 3 was bonded and fixed, and a pair of ferrules 1 were inserted from both ends of the sleeve 5 and processed into a convex spherical shape inside. When the acceleration of exposing the optical connector with the tip surfaces 1d in contact with each other to hot water at 80 ° C. was tested, the optical connector member such as a ferrule made of a zirconia sintered body showed the above-mentioned phase. Due to the transformation, the abutted portion of the tip surface 1d is deformed, causing a problem that the radius of curvature of the convex spherical surface of the ferrule tip surface 1d is increased.
[0014]
As a result, the radius of curvature of the ferrule tip surface 1d is increased, so that when the tip surfaces 1d of the pair of ferrules are reconnected to each other, a gap is generated between the tip surfaces 1d even if there is a spring force of the optical connector. In addition, there is a problem that poor connection or excessive connection loss occurs.
[0015]
[Means for Solving the Problems]
Accordingly, the present invention has been made in view of the above problems, and in a ferrule in which a through hole for accommodating an optical fiber is formed at the center of a zirconia sintered body formed in a cylindrical shape, Provided is a ferrule in which a rhombohedral phase is formed at a depth of at least 50 μm from a tip surface of a body.
[0016]
Further, an arithmetic average surface roughness (Ra) on a front end surface of the fired body is set to 0.01 to 0.1 μm.
[0017]
Further, in the ferrule described above, the tip surface of the cylindrical zirconia sintered body is ground with a grindstone using diamond abrasive grains having an average particle diameter of 9 μm or more, so that the tip surface has a rhomboid body. It is characterized by forming a crystal phase.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0019]
As shown in FIG. 1, the ferrule 1 of the present invention has a through hole 1a for inserting an optical fiber in the center of a zirconia fired body 100 formed in a cylindrical shape, and the rear end of the through hole 1a has an optical fiber. In order to facilitate the insertion, a conical portion 1b is provided, and a boundary between the outer peripheral portion 1c and the substantially convex spherical end surface 1d is provided with a chamfered portion 1e serving as a guide surface when the sleeve is inserted.
[0020]
The ferrule 1 of the present invention is used for an optical connector W. The optical connector W includes an optical fiber fixture 10 and a sleeve 5. As shown in FIG. 3, the optical fiber fixture 10 has a metal support 2 bonded to the rear end of the zirconia fired body 100 of the ferrule 1. Then, after inserting the element wire 30 of the optical fiber 3 into the through hole 1a and fixing it with the adhesive 4, the tip surface 1d is polished into a convex spherical shape having a curvature radius of about 7 to 25 mm.
[0021]
As shown in FIG. 2, the optical fibers 3 can be connected to each other by inserting a pair of ferrules 1 from both ends of the sleeve 5 and pressing them with a spring or the like to bring the tip surfaces 1 d into contact with each other. it can.
[0022]
The zirconia sintered body that constitutes the ferrule 1 contains ZrO ₂ as a main component and Y ₂ O ₃ as a stabilizer, and uses partially stabilized zirconia ceramics mainly composed of tetragonal crystals. In the case of manufacturing such a ferrule 1 made of zirconia ceramics, the ferrule 1 is obtained by molding the above raw material powder into a predetermined shape by extrusion molding, injection molding, press molding or the like, followed by firing.
[0023]
As the zirconia ceramics, those having an average crystal grain size of 0.1 μm to 0.5 μm and a porosity of 3% or less are applicable. If the crystal grain size exceeds 0.5 μm, the gap between the crystals becomes large and a good outer peripheral surface cannot be obtained. In addition, when the raw materials are mixed and crushed by a ball mill or the like, the particle size is adjusted to 0.1 μm or less stably. It is difficult to perform the treatment, and the diameter is increased to 0.1 μm or more because the diameter of the crystal grows after firing. The porosity indicates the percentage of voids contained in the individual ferrule 1 as a percentage. If the porosity exceeds 3%, the porosity deteriorates the outer peripheral surface roughness.
[0024]
The ferrule 1 of the present invention is characterized in that a rhombohedral crystal phase is formed in a range of a depth of at least 50 μm from the tip surface 1d of the zirconia fired body 100.
[0025]
The rhombohedral phase according to the present invention is generated by subjecting a partially stabilized zirconia surface layer to a phase transformation from a cubic and tetragonal structure by machining. As a result, compressive stress is generated in the surface layer. Generally, ceramics such as zirconia are weak in tensile stress and easily cracked, but have relatively strong compressive residual stress.
[0026]
Therefore, the ferrule 1 having the rhombohedral phase has a compressive residual stress on its tip surface 1d, and the tensile stress on its surface does not increase even if a tensile mechanical load is applied. Therefore, zirconia has a feature that cracks are hardly generated from its surface and can withstand a larger tensile load.
[0027]
Further, the ferrule 1 having the rhombohedral phase can withstand a larger tensile load. For example, the bending strength is improved by 10 to 40%, and the toughness is improved by a factor of 2 to 3. The ferrule 1 having a further strengthened rhombohedral crystal phase has a feature that even if the surface is damaged, the rate at which the scratch propagates to a crack that causes the tip surface 1d of the ferrule 1 to be damaged is small. Further, the ferrule 1 having the strengthened rhombohedral crystal phase has a feature that it is not necessary to reduce the roughness of the finished surface because the notch sensitivity is small.
[0028]
Here, the region of the front end face 1d of the zirconia fired body 100 is a contact region with a member to be contacted, which is a component in the optical connector W, and is generally based on the center of the through hole 1a. The diameter is within a range of 250 μm.
[0029]
When the rhombohedral phase is formed in a range shallower than 50 μm from the tip surface 1d, the tip surface 1d is cut by several tens of μm in the final polishing after bonding and fixing the optical fiber 3 to the through hole 1a. However, there is a problem that the rhombohedral crystal phase disappears. Further, since the rhombohedral phase is generated on the tip end face 1d by the processing, the rhombohedral phase is not formed deeper than 800 μm. Therefore, it is preferable that the depth range is at least 50 μm and at most 800 μm. .
[0030]
That is, by forming this rhombohedral crystal phase from the tip face 1d of the zirconia fired body 100 to at least 50 μm or more and at most 800 μm, the tip face 1d is finally polished after the optical fiber 3 is bonded and fixed, and 20 to Even if it is cut by about 45 μm, a rhombohedral phase of at least 5 μm or more is left on the tip face 1 d. Therefore, a pair of ferrules 1 are inserted from both ends of the sleeve 5 to form a convex spherical surface inside. When a test is performed in which the optical connector is exposed to hot water at 80 ° C. in a state in which the tip surfaces 1d processed into a shape are in contact with each other, the ferrule 1 made of a zirconia sintered body causes the tip surface 1d due to phase transformation. This prevents the radius of curvature of the convex spherical surface that has contacted from changing, so that when the tip surfaces 1d of the pair of ferrules are reconnected to each other, the tip surfaces 1d can be connected without gaps by the spring force of the optical connector. Can be, it is no longer results in a splice loss.
[0031]
Here, the contacted member that comes into contact with the ferrule 1 is the ferrule 1 that is brought into contact when the ferrules 1 of the present invention come into contact with each other. In the connection between the ferrule 1 and a waveguide (not shown), the ferrule 1 and the waveguide are used.
[0032]
Here, as a method for confirming the existence of the rhombohedral phase, X-ray diffraction of the ferrule tip face 1d is performed as shown in FIG. 4, and the peak positions of the tetragonal crystal and the cubic crystal are overlapped. The presence of the rhombohedral phase can be confirmed by the fact that the low angle side of the peak is broad (see zirconia ceramics journal No. 4, paragraphs 31 to 45).
[0033]
Here, the m phase indicates a monoclinic phase, the c + t phase indicates a cubic phase and a tetragonal phase, and the r phase indicates a rhombohedral phase.
[0034]
The structure can also be confirmed by taking a half-section of the ferrule 1 and confirming the structure by SEM. Since the rhombohedral phase is subjected to compressive residual stress, the average grain size is slightly larger than that of a monoclinic, tetragonal, or cubic crystal which is usually present. Therefore, the region where the grain size is changed can be determined from the SEM photograph of the crystal structure, and the depth can be confirmed.
[0035]
As shown in the lattice model of FIG. 5, the rhombohedral phase has zirconium (Zr) 21 located at each vertex and substantially at the center of each surface, and a sublattice in which a part thereof is replaced with yttrium (Y). It is based on a fluorite-type structure consisting of a sublattice having oxygen (O) atoms 22 disposed at the vertices inside. The lattice constants of the rhombohedral phase are a = 5.12 to 5.24 angstroms (Å) and α = 89.2 to 89.8 degrees. That is, the lattice volume of the rhombohedral phase is 0.5-3% larger than that of the cubic and tetragonal structures.
[0036]
The ferrule 1 is characterized in that the arithmetic mean surface roughness (Ra) of the tip surface 1d is in the range of 0.1 to 0.01 μm.
[0037]
The tip surface 1d of the arithmetic average surface roughness (Ra) can be set to a range of 0.1 to 0.01 μm by processing using a grinding wheel having a relatively coarse particle size. Within this range, the rhombohedral phase remains even after the optical fiber 3 is bonded to the ferrule 1 and the end face 1d and the end face of the optical fiber 3 are finish-polished, so that it is stable against thermal degradation. Will do.
[0038]
Here, if it is a rough surface exceeding 0.1 μm, a grinding flaw is left on the tip end surface 1 d of the ferrule 1 in the final polishing finish, which is not preferable as an optical connector, and is less than 0.01 μm. If the surface is fine, the layer of the rhombohedral phase formed is too small and is removed in the final polishing, so that the arithmetic average surface roughness (Ra) is in the range of 0.1 to 0.01 μm. It is desirable to be within.
[0039]
The material of the support 2 fixed to the rear part of the ferrule 1 of the present invention is made of metal such as stainless steel, copper alloy nickel-plated, brass nickel-plated, nickel-white nickel-plated. Can be used.
[0040]
Next, a method for processing the ferrule 1 of the present invention will be described in detail.
[0041]
First, the starting material ZrO ₂ contains Al ₂ O ₃ , SiO ₂ , TiO ₂ , or CaO, Na ₂ O, Fe ₂ O _3, or the like as impurities. , Or refined by a method such as gravity separation utilizing the difference in specific gravity to increase the purity. Then, ZrO _{2 Y 2 O 2} was added and mixed 3-5 mol%, and settle neutralizing co is reacted, solid solution by a method such as hydrolysis.
[0042]
Next, the obtained raw material is formed into a predetermined shape by extrusion molding, press molding, injection molding, or the like, and if necessary, cutting or the like is performed, followed by firing in an air atmosphere.
[0043]
At this time, in order to obtain a small average crystal grain size of 0.5 μm or less, firing at a low temperature of 1200 to 1550 ° C. and a dense sintered body must be performed. Thus, it can be achieved by increasing the specific surface area. The ferrule 1 can be obtained by further polishing and grinding this sintered body.
[0044]
Here, the firing temperature and the average crystal grain size are in a proportional relationship, and the higher the firing temperature, the larger the average crystal grain size. In the zirconia sintered body of the present invention, the average particle size is 0.12 μm at 1200 ° C., 0.23 μm at 1370 °, and 0.5 μm at 1550 °.
[0045]
Next, the tip surface 1d of the zirconia produced by the above-described sintering method is subjected to grinding to induce rhombohedral zirconia in the surface layer of the zirconia.
[0046]
The ratio of the rhombohedral phase and the depth from the surface generated by the above processing can be controlled by the grain size of the grinding wheel.
[0047]
The method for processing the substantially convex spherical surface of the tip surface 1d of the ferrule 1 of the present invention includes two methods, namely, a grinding wheel shape transfer type and a spherical surface forming.
[0048]
Among these, as shown in FIG. 6, the grindstone shape transfer die rotates a cylindrical grindstone 113 having a concave portion 112 with a curvature radius of 10 to 25 mm on the outer peripheral surface 111 at a speed of about 500 to 20,000 rpm, and moves the ferrule 1 to the grindstone. The shape of the grindstone 113 is transferred to the tip surface 1d of the ferrule 1 by rotating the ferrule 1 at a speed of 1/2 to 1/100 with respect to the grindstone 113 and abutting the tip surface 1d perpendicularly to the grindstone 113. This is the processing method used.
[0049]
Next, as shown in FIG. 7, in the spherical surface forming, the spherical cup grindstone 115 is arranged at an angle with respect to the rotation center of the ferrule 1, and both the ferrule 1 and the spherical cup grindstone 115 are rotated to project on the tip surface 1d. This is a processing method for forming a spherical surface.
[0050]
In any of the above two methods, a rotating mechanism of the grindstones 113 and 116 and a rotating mechanism of the ferrule 1 having sufficient rigidity are used. Further, when an overload occurs during processing, the load is automatically released. For example, by using an air spindle or an automatic overload control device, a substantially convex spherical surface can be formed without causing chipping.
[0051]
Here, it is desirable that the average grain size of the grindstone is 9 μm or more. If a diamond grindstone having an average grain size of less than 9 μm is used, the depth from the surface of the rhombohedral crystal phase generated on the tip end face 1d becomes shallow, and the final It is desirable that the thickness be 9 μm or more, since all of them are removed by the final polishing.
[0052]
Further, by performing compression processing such as shot peening after grinding processing, the ratio of the rhombohedral crystal phase and the depth from the surface can be further increased, and zirconia more stable against thermal degradation can be obtained.
[0053]
As described above, the method for producing a ferrule 1 having a rhombohedral phase according to the present invention includes the steps of: firing zirconia from ZrO ₂ and an oxide of Y ₂ O ₃ ; grinding the zirconia; And the step of inducing
[0054]
The ferrule 1 of the present invention can be applied to both single mode and multi mode.
[0055]
FIG. 2 shows an optical connector for connecting the optical fibers 4 to each other. However, the ferrule 1 and the sleeve 2 may be used for an optical module for connecting an optical element such as a laser diode or a photodiode to an optical fiber. it can.
[0056]
Further, the ferrule 1 according to the present invention can be applied to various members used for connecting the optical fibers 3 or between the optical fibers 3 and various optical elements. For example, the present invention can be applied to a splicer used for completely connecting the optical fibers 3 to each other, a dummy ferrule used for an optical module, and the like.
[0057]
【Example】
Hereinafter, embodiments of the present invention will be described.
[0058]
A ferrule 1 made of zirconia is prepared as a standard SC ferrule having an outer diameter of 2.500 mm of the outer peripheral portion 1c, an inner diameter of 0.126 mm of the through hole 1a, a concentricity of the inner and outer diameters of 1 μm, and a length of 10.5 mm. 1d was formed by grinding using the spherical surface creation method shown in FIG.
[0059]
Here, the average particle size of the diamond grindstone used for the grinding was changed to 2, 3, 5, 8, 9, 12, and 15 μm.
[0060]
Next, the single mode optical fiber 3 was inserted into the through-hole 1a, fixed using an epoxy-based adhesive 4, and subjected to final finishing polishing to obtain an optical fiber fixture 10.
[0061]
After halving each sample around the through-hole 1a to expose the cross-sectional shape, a photograph of the tissue cross-section was taken at 5,000 times using an SEM, and a region where the particle size was changed from the SEM photograph. And the depth was measured. The arithmetic mean surface roughness (Ra) of the tip surface 1d at that time was also measured.
[0062]
Next, for each sample, after the optical fiber 3 was bonded and fixed, the tip end face 1d was finally finished and polished, and then components such as a frame, a housing, and a spring were assembled to obtain an SC optical connector.
[0063]
The radius of curvature of each end face 1d of each optical connector is measured, and the two optical fiber fixtures 2 are connected to each other using the split sleeve 5 as shown in FIG. After being immersed in pure water for 14 days and taken out, the radius of curvature of the tip surface 1d of each sample was measured again, and the value obtained by subtracting the value of the radius of curvature before the test from the radius of curvature after the test was obtained.
In this example, a sample having a rhombohedral crystal phase exceeding 800 μm could not be produced.
Table 1 shows the results.
[0064]
[Table 1]

[0065]
From the above, when the particle size of the diamond grindstone is 8 μm or less, the depth from the surface of the rhombohedral phase is less than 50 μm, the arithmetic average surface roughness (Ra) is less than 0.01 μm, and the variation value of the radius of curvature is The value greatly exceeds 1 mm, and it can be seen that the thermal deterioration is large. On the other hand, when the particle size of the diamond wheel of the present invention is 9 μm or more, the depth from the surface of the rhombohedral phase is 50 μm or more, the arithmetic average surface roughness (Ra) is 0.01 μm or more, and the curvature is The variation value of the radius was 1 mm or less, and the thermal deterioration was significantly improved.
[0066]
【The invention's effect】
As described above, according to the present invention, in a ferrule in which a through hole for accommodating an optical fiber wire is formed at the center of a cylindrical zirconia sintered body, at least 50 μm from a tip end surface of the fired body. Since the rhombohedral phase is formed at a depth of 800 μm at the maximum, it is possible to obtain a ferrule having excellent durability in a high-temperature atmosphere where moisture is present.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a ferrule of the present invention.
FIG. 2 is a sectional view showing an optical connector using the ferrule of the present invention.
FIG. 3 is a sectional view showing an optical fiber fixture using the ferrule of the present invention.
FIG. 4 is an X-ray diffraction diagram of the tip surface of the ferrule of the present invention.
FIG. 5 is a diagram showing a lattice model of a rhombohedral phase of the present invention.
FIG. 6 is a view showing a ferrule processing method of the present invention.
FIG. 7 is a view showing a ferrule processing method of the present invention.
[Explanation of symbols]
1: Ferrule 1a: Through hole 1b: Conical portion 1c: Outer peripheral portion 1d: Tip surface 1e: Chamfered portion 2: Support 3: Optical fiber 4: Adhesive 5: Sleeve 21: Zirconium 22: Oxygen 30: Element wire 111 : Outer peripheral surface 112: concave portion 113: whetstone 115: cup whetstone 116: whetstone

Claims (3)

In a ferrule in which a through hole for accommodating an optical fiber is formed at the center of a cylindrical zirconia sintered body, a rhombohedral phase is formed in a range of at least 50 μm deep from a front end surface of the fired body. Is formed. The ferrule according to claim 1, wherein an arithmetic mean surface roughness (Ra) at a tip end surface of the fired body is 0.01 to 0.1 m. 3. The ferrule according to claim 1, wherein the tip surface of the zirconia sintered body formed into a cylindrical shape is ground with a grindstone using diamond abrasive grains having an average grain diameter of 9 μm or more. A method of processing a ferrule, wherein a rhombohedral phase is formed on a tip surface.

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