JP2002055258A - Optical fiber ferrule and its machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ferrule 1 that has stable optical characteristics and that has no problem in appearance. SOLUTION: In a nearly cylindrical, zirconia ceramics-made optical fiber ferrule that has a through-hole for storing an optical fiber in the axial direction, a connecting part between the through-hole and the tip end face, before the optical fiber is fixedly stuck, is designed to have a radius of curvature R1 in the range of 0.0005 mm<=R1<=0.02 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber ferrule for fixing an optical fiber used for optical communication and the like.

[0002]

2. Description of the Related Art Conventionally, an optical fiber ferrule for fixing an optical fiber used for optical signal processing such as optical communication is formed by an optical connector used for connecting optical fibers or a semiconductor laser and an optical fiber. It is used for semiconductor laser modules and the like that are configured.

As an example, as shown in a schematic diagram of FIG. 8, an optical connector is made of zirconia ceramics which has a single mode optical fiber 5 made of quartz, which is adhered and fixed, and which is polished to a substantially convex spherical surface on a tip end surface 11. The optical fiber ferrule (hereinafter referred to as ferrule 1) is configured such that the distal end surfaces 11 thereof are brought into contact with each other and optically connected.

FIG. 9 shows a ferrule 1 before bonding the optical fiber 5 and polishing the end face 11 thereof. In the ferrule 1, the shape of the connecting portion 16 between the through hole 12 and the tip surface 11 is not particularly defined, so that chipping occurs at the connecting portion 16 in the ferrule 1 in which the tip surface 11 is finished by conventional grinding. Also, in the ferrule 1 which has been polished to remove the chipping, a large curved surface dripping has occurred at the joint portion 16 from the distal end surface 11 to the inner peripheral surface.

Further, it is specified that the connecting portion 18 between the outer peripheral surface 13 of the ferrule 1 and the front chamfered portion 14 and the connecting portion 19 between the outer peripheral surface 13 and the rear end chamfered portion 17 are curved. Most ferrules 1 have a curvature radius of 0.01 mm to 0.0 due to poor workability.
Only about 2 mm was processed.

[0006]

In the conventional ferrule 1 for an optical fiber, chipping or sagging occurs at the joint 16 between the through hole 12 and the tip end surface 11.
Since the optical fiber 5 is not completely covered with the through-hole 12 at the distal end surface 11 and is not sufficiently fixed in the step of polishing the distal end surface 11 after the optical fiber 5 is bonded, the optical fiber 5 is cracked. However, there is a problem that chipping and sagging remain after polishing and the appearance is dirty.

When the ferrule 1 is used as an optical connector, when the ferrule 1 is inserted into a phosphor bronze sleeve (not shown), the sleeve is damaged at the joint 18 between the outer peripheral surface 13 and the tip chamfered portion 14, and the ferrule is damaged. 1 outer peripheral surface 13
There is a problem that the shavings of the black sleeve adhere to the surface, and in the end, the shavings adhere to the tip surface of the optical fiber and the connection loss deteriorates.In addition, the cylindricity and straightness of the sleeve deteriorate due to repeated insertion and removal. As a result, there is a problem that connection loss is not stable.

Further, when a metal flange is pressed into the rear end face 17, the flange may be bent because the metal flange is not inserted smoothly at the joint 19 between the outer peripheral face 13 and the rear end chamfered part 17. There has been a problem that the ferrule 1 is broken or broken.

[0009]

In view of the above, the present invention provides
In a substantially cylindrical ferrule for an optical fiber made of zirconia ceramics having a through hole for accommodating an optical fiber in an axial direction, a radius of curvature R1 of a connecting portion between the through hole and the front end surface before bonding and fixing the optical fiber is set to 0. .0005mm
≦ R1 ≦ 0.02 mm.

Further, the present invention is characterized in that in the ferrule for an optical fiber, after polishing the inner surface of the through hole, the tip surface of the ferrule is processed using a diamond grindstone having an average particle diameter of 2 μm or less.

That is, according to the present invention, when the tip surface of the ferrule is machined, a fine diamond grindstone having an average particle size of 2 μm or less is used, so that the radius of curvature R1 at the junction between the through hole and the tip surface is set to 0.1. 0005 mm to 0.02 mm, thereby preventing chipping and sagging of the joint. Then, if the optical fiber is inserted and adhered to the ferrule and the end surface is polished, cracking of the optical fiber can be prevented since the optical fiber is completely covered with the through hole.

Further, according to the present invention, there is provided an optical fiber ferrule made of a substantially cylindrical zirconia ceramic having a through hole for accommodating an optical fiber in an axial direction. The curvature radius R2 of the connecting portion with the outer peripheral surface is set in a range of 0.03 mm ≦ R2 <5 mm.

The present invention also provides a ferrule for an optical fiber made of a substantially cylindrical zirconia ceramic having a through hole for accommodating an optical fiber in an axial direction, comprising a chamfered portion on the outer periphery of a rear end surface, and the rear end chamfered portion. The radius of curvature R3 at the joint between the outer peripheral surface and the outer peripheral surface is set in a range of 0.03 mm ≦ R3 <2 mm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a ferrule for an optical connector showing an embodiment of the present invention. A tip chamfered portion 14 is provided at a connecting portion between a substantially convex spherical tip surface 11 and an outer peripheral surface 13 of the ferrule 1. A fiber insertion guide 1 having a conical through hole 12 in the center of the ferrule 1 from a distal end face 11 in the axial direction.
2a and extends to the rear end 15. Further, a rear end chamfered portion 17 is provided at a connection portion between the rear end portion 15 and the outer peripheral surface 13, and the flange 2 is fixed.

The flange 2 described above as shown in FIGS.
Is disposed in the plug housing 4 in a state of being urged by the spring 3 or the like, and an attachment member 6 such as a screw is provided on the outer periphery of the plug housing 4. The optical fiber 5 is inserted into the through hole 12 of the ferrule 1 and epoxy-bonded. The connector plug 8 is fixed by using an adhesive 100 such as an adhesive. On the other hand, the adapter 9 is provided with a sleeve 7 for inserting the ferrule 1 and a screw 91 that matches the mounting member 6.

Now, the connector plug 8 is inserted from both sides of the adapter 9, the ferrule 1 is inserted into the sleeve 7, and the tip surfaces 11 of the ferrules 1 are brought into contact with each other.
An optical fiber connector can be formed by fixing with the attachment member 6.

The ferrule 1 has an outer diameter D = φ2.5 mm,
Length L = 10.5mm, through hole d = φ0.126mm,
Are common dimensions.

Next, the connecting portion 16 of the present invention between the through hole 12 and the front end surface 11, the connecting portion 18 between the outer peripheral surface 13 and the leading end chamfering portion 14, and the outer peripheral surface 13 and the rear end chamfering portion 17 are connected. FIG. 4A to FIG. 4C for the connection portion 19.
This will be described with reference to FIG.

In FIG. 4A, the radius of curvature of the connecting portion 16 between the through hole 12 and the front end surface 11 is R1, and the radius of curvature is 0.001.
The range is 05 mm ≦ R1 ≦ 0.02 mm. If the radius of curvature R1 is less than 0.0005 mm, the ferrule 1 is too sharp when glass or ceramic is used.
Chipping is likely to occur during the processing of No. 1 and chipping occurs due to the impact of collision with the tray during carrying. If the radius of curvature R1 exceeds 0.02 mm, the optical fiber is not sufficiently fixed in the polishing after bonding the fiber because it is not completely covered with the through hole 12 at the tip end surface 11, and the optical fiber is cracked. In some cases, after polishing, sagging or chipping remains and the appearance becomes dirty. Here the tip surface 11
Can achieve the same effect on both flat and spherical surfaces.

In the present invention, the connecting portion 16 between the through hole 12 and the tip end surface 11 is defined as a radius of curvature. This is not limited to the R-shape, but includes notching, chipping, chipping, and the like of the connecting portion 16. Can be done. In this case, the numerical value is defined by using a larger value in the radial direction of the distal end surface 11 and the longitudinal direction of the through hole 12.

For example, if there is a chip of 0.0008 mm in the radial direction and 0.0003 mm in the longitudinal direction at the connecting portion 16, the maximum value is 0.0008 mm, which is within the range of the present invention. Further, if there is a chip of 0.032 mm in the radial direction and 0.020 mm in the longitudinal direction, it is out of the scope of the present invention.

Next, in FIG. 4 (b), the radius of curvature R2 of the connecting portion 18 between the outer peripheral surface 13 and the leading end chamfered portion 14 is in the range of 0.03 mm ≦ R2 <5 mm. If the radius of curvature R2 is less than 0.03 mm, when the ferrule 1 is inserted into the phosphor bronze sleeve, the outer circumferential surface 13
The sleeve 18 is damaged at the connecting portion 18 between the ferrule 1 and the tip chamfering portion 14, and the black sleeve shavings adhere to the outer peripheral surface 13 of the ferrule 1 to make the appearance dirty.
In the end, the shavings adhere to the front end surface of the optical fiber and cause a loss in connection. Furthermore, repeated insertion / extraction degrades the cylindricity and roundness of the sleeve, resulting in unstable connection loss. Also, the radius of curvature R2 is 5 m
When the length is more than m, the straight portion of the outer peripheral surface 13 is shortened, and is not firmly held by the sleeve.

Further, in FIG. 4C, the radius of curvature R3 of the connecting portion 19 between the outer peripheral surface 13 and the rear end chamfered portion 17 is set to 0.
03 mm ≦ R3 <2 mm. Radius of curvature R
3 is less than 0.03 mm, the outer peripheral surface 13 and the rear end chamfered portion 1 when the metal flange 2 is pressed into the rear end surface 17.
At the connecting portion 18 with the flange 7, the flange 2 may be bent or the ferrule 1 may be broken or broken because it cannot be inserted smoothly. On the other hand, if the radius of curvature R3 is 2 mm or more, the straight portion of the outer peripheral surface 13 becomes short, and it becomes impossible to secure a press input to the flange 2.

Here, the connecting portions 16, 18, and 19 are represented by R
1, R2, and R3 are used as the radii of curvature. However, the shape may not be a perfect circle but may be an ellipse or a shape in which both ends of a corner are curved.

For example, FIGS. 5A to 5D show cross-sectional views of various R shapes in the connecting portion 16.

FIG. 5A shows a complete circle. (B) is an ellipse and is elongated in the vertical direction in the figure. (C)
Has a straight central part and circular ends. (D)
Indicates a projecting type in which two straight lines join at an intermediate point. Each of the shapes has a cross-sectional shape connected by a smooth line.

In the figure, the portion of R indicates a long value in the vertical and horizontal directions, and if R is within the range of the present invention, the same effect can be obtained.

The ferrule 1 of the present invention is in a state before the optical fiber is bonded and the tip end surface 11 is polished. Therefore, the ferrule 1 adheres an optical fiber to the through hole 12 and polishes the tip end surface 11. This polishing step eliminates the R of the connecting portion 16, does not cause cracks in the optical fiber, and is clean in appearance. Becomes

As described above, the radii of curvature of the connecting portions 16, 18, and 19 are respectively 0.0005 mm ≦ R1 ≦ 0.02 m
m, 0.03 mm ≦ R2 <5 mm, 0.03 mm ≦ R3
By setting the range of <2 mm, the optical characteristics are stabilized,
Moreover, the ferrule 1 having no problem in appearance can be obtained.

Next, as a material of the ferrule 1, a ceramic containing zirconia as a main component is particularly suitable.
Specifically, ZrO ₂ is used as a main component, and Y ₂
A partially stabilized zirconia ceramic containing at least one of O ₃ , MgO, CaO, CeO ₂ , Dy ₂ O _{3 and the} like and mainly composed of tetragonal crystals is used. 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.

As the zirconia ceramics, those having an average crystal grain size of 0.1 to 1.0 μm and a porosity of 3% or less can be applied. Here, the average crystal grain size is 1.
If it exceeds 0 μm, the gap between the crystals becomes large and a good outer peripheral surface cannot be obtained, and it is difficult to stably adjust the particle size to 0.1 μm or less when pulverizing with a ball mill or the like at the time of mixing the raw materials. Thereafter, the diameter is set to 0.1 μm or more because the diameter of the crystal further increases because the crystal grows. The porosity represents the percentage of voids contained in the individual ferrule as a percentage. If the porosity exceeds 3%, the porosity deteriorates the surface roughness of the tip end surface 11.

The material of the flange 2 fixed to the rear end 15 of the ferrule 1 is stainless steel, copper alloy nickel-plated, brass nickel-plated, nickel-white nickel-plated, etc. Can be used.

The ferrule 1 can be applied to both single mode and multi mode.

Next, the connecting portion 1 of the ferrule 1 of the present invention will be described.
The processing method No. 6 will be described.

The inner peripheral surface of the through hole 12 of the ferrule 1 is finished to a predetermined inner diameter by polishing in advance. Thereafter, a substantially convex spherical surface processing is performed on the distal end surface 11 so as to have a curvature radius of 10 mm to 25 mm. This spherical surface forming processing includes two methods, a grinding wheel shape transfer type and a spherical creation type.

As shown in FIG. 6, the grinding wheel shape transfer die has a concave portion 1 having a radius of curvature of 10 to 25 mm on the outer peripheral surface 111 thereof.
12 to 500 to 200
The ferrule 1 is rotated at a speed of about 00 rpm, the ferrule 1 is rotated at a rotation ratio of 1/2 to 1/100 with respect to the grindstone 113, and the tip surface 11 abuts on the grindstone 113 vertically. Grinding wheel 11 on the tip surface 11
This is a processing method in which the shape of No. 3 is transferred.

If a fine diamond grindstone having an average particle diameter of 2 μm or less is used as the grindstone 113, the radius of curvature of the connecting portion 16 is finished to 0.0005 mm to 0.02 mm.

Next, as shown in FIG. 7, in spherical surface forming, the spherical cup grindstone 115 is disposed so as to be inclined with respect to the center of rotation of the ferrule 1, and both the ferrule 1 and the spherical cup grindstone 115 are rotated to form a tip surface. 11 is a processing method for forming a convex spherical surface.

The tip 11 of the spherical cup grinding stone 115
When a fine diamond grindstone having an average particle diameter of 2 μm or less is used for 6, the radius of curvature of the connecting portion 16 is 0.0005 mm or more.
Finished to 0.02 mm.

In any of these two methods, the grinding wheel 113
For example, an air spindle or an automatic overload control device that automatically releases the load when an overload occurs during machining by using a rotary mechanism of the ferrule 1 and a rotary mechanism of the ferrule 1 having sufficient rigidity. By using this, the connecting portion 16 can have a minute radius of curvature as described above without causing chipping.

In each of the two methods, the radius of curvature of the joint 16 of the ferrule 1 is set to 0.0005 mm.
In addition to being able to finish to 0.02 mm, since the ferrule 1 does not have the optical fiber 5, it can be automatically supplied and discharged at the time of processing, and since the ferrule 1 can be rotated to perform processing, high speed and stable quality can be achieved. Can be formed.

The reason why the average particle size of the grindstone is set to 2 μm or less is that if it exceeds 2 μm, the sagging of the hole becomes large and chipping also occurs. And average particle size 2μ
m or less, the surface roughness of the front end surface 11 can be made a mirror surface of 0.2 μm or less, and according to this processing method, the front end surface 11 and the joint 1
6 can be processed simultaneously.

Next, with regard to the processing of the connecting portions 18 and 19, an edge is generated at the connecting portions 18 and 19 by polishing the outer peripheral surface 13 after processing the front end chamfering portion 14 and the rear end chamfering portion 17. In order to process the connecting portions 18 and 19 into a curved surface, brush polishing is generally performed, and the sizes of the radii of curvature R2 and R3 depend on the average particle size of the diamond abrasive grains and the processing time. 0.03 mm ≦ R2 <5 m of the present invention
m, 0.03mm ≦ R3 <2mm
It is appropriate that the average particle diameter of the diamond abrasive grains is 1 μm to 5 μm, and the processing time is 10 minutes to 60 minutes.

As described above, the curvature radii of the connecting portions 16, 18, and 19 are respectively 0.0005 mm ≦ R1 ≦ 0.02 m
m, 0.03 mm ≦ R2 <5 mm, 0.03 mm ≦ R3
By setting the range of <2 mm, the optical characteristics are stabilized,
Moreover, the ferrule 1 having no problem in appearance can be obtained.

[0046]

EXAMPLE Here, an experiment was conducted by the following method.

The zirconia ceramic single mode ferrule shown in FIG. 1 has an outer diameter D = φ2.5 mm, a length L = 10.5 mm, a through hole d = φ0.126 mm, and a connection between the through hole 12 and the tip surface 11. The radius of curvature of the part 14 is 0.0004 mm, 0.0006 mm, 0.002 m
m, 0.005mm, 0.010mm, 0.020m
m, 0.025 mm, 100 samples each of which was changed to 0.03 mm, an optical fiber was inserted through the ferrule 1 and fixed, and then only the optical fiber tip surface was finish-polished,
The presence or absence of cracks on the optical fiber tip surface after polishing and the state of the connecting portion 14 were observed. Here, the case where the sagging or chipping remained in the joint portion 14 was counted as defective.

Table 1 shows the results. The numbers in the table are the defective quantities.

[0049]

[Table 1]

From this result, in the optical fiber connector using the ferrule 1 in which the radius of curvature of the connecting portion 16 is 0.0004 mm, chipping occurs in the connecting portion 16.
The optical fiber connector using the ferrule 1 of 025 mm and 0.03 mm has cracks, sagging, and chipping.
002 mm, 0.005 mm, 0.010 mm, 0.0
It can be seen that the optical fiber connector using the 20 mm ferrule 1 has no crack, sagging or chipping.

Next, similarly to the above, the outer diameter D = φ of the single mode ferrule made of zirconia ceramic shown in FIG.
2.5 mm, length L = 10.5 mm, through hole d = φ0.
126 mm, the radius of curvature of the connecting portion 18 between the outer peripheral surface 13 and the tip chamfered portion 14 is 0.025 mm, 0.030 m
m, 0.1 mm, 1.0 mm, 4.0 mm, 5.0 m
5 samples each changed to m and 6.0 mm
The insertion and removal were repeated 0 times, and the connection loss values before and after the test were confirmed.

Table 2 shows the results. The values in the table are the average values of five samples.

[0053]

[Table 2]

From this result, it is found that the connection loss of the sample having the radius of curvature of the connecting portion 18 of 0.025 mm is deteriorated during the insertion and removal, and the connection loss of the sample having the radius of curvature of 5 mm and 6 mm is poor from the initial state. Understand. On the other hand, 0.030 mm, 0.10 mm, 1.
It can be seen that the 0 mm and 4.0 mm samples have stable connection loss before and after repeated insertion and removal.

Finally, similarly, the outer diameter D = φ of the single mode ferrule made of zirconia ceramic shown in FIG.
2.5 mm, length L = 10.5 mm, through hole d = φ0.
126 mm, the radius of curvature of the connecting portion 19 between the outer peripheral surface 13 and the rear end chamfered portion 17 is 0.025 mm, 0.030 m
m, 0.1mm, 1.0mm, 1.5mm, 2.0m
50 samples each having a diameter of m and 3.0 mm were prepared, and a metal flange 2 was press-fitted to check whether the flange 2 was bent, and the ferrule 1 was cracked or broken.

Table 3 shows the results. The numbers in the table are the defective quantities.

[0057]

[Table 3]

From these results, it is found that a sample having a joint portion 19 having a curvature radius of 0.025 mm bends a flange, breaks or breaks a ferrule, and a sample having a curvature radius of 2 mm and 3 mm cannot easily be pressed and cannot be easily removed. Things have also occurred. In comparison, 0.030 mm of the present invention,
It can be seen that the 0.10 mm, 1.0 mm, and 1.5 mm samples have no abnormality in both the flange 2 and the ferrule 1 after the flange 2 is press-fitted, and that the flanges do not come off easily.

[0059]

As described above, according to the present invention, in a ferrule for an optical fiber made of zirconia ceramics,
By setting the radius of curvature of the joint between the through hole and the tip surface before fixing the optical fiber in the range of 0.0005 mm ≦ R1 ≦ 0.02 mm, the ferrule 1 has stable optical characteristics and has no problem in appearance. Can be obtained.

According to the present invention, the radii of curvature of the connecting portion between the outer peripheral surface and the front chamfered portion and the curvature radius of the connecting portion between the outer peripheral surface and the rear end chamfered portion are respectively 0.03 mm ≦ R2 <5 mm, 0.03 m
By setting m ≦ R3 <2 mm, the optical characteristics are stabilized,
Moreover, it is possible to obtain the ferrule 1 in which the bending of the flange and the application of the ferrule do not occur.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state where a flange is fixed to an optical fiber ferrule of the present invention.

FIG. 2 is a perspective view showing an optical fiber connector using the optical fiber ferrule of the present invention.

FIG. 3 is a longitudinal sectional view showing an optical fiber connector using the optical fiber ferrule of the present invention.

4 (a) to 4 (c) are longitudinal sectional views showing a connecting portion of the ferrule for an optical fiber of the present invention.

FIG. 5 is a diagram illustrating a radius of curvature of a joint according to the present invention.

FIG. 6 is a view showing a method of processing the ferrule for an optical connector of the present invention.

FIG. 7 is a view showing a method for processing the ferrule for an optical connector of the present invention.

FIG. 8 is a schematic view showing a joint portion of a general optical fiber connector.

FIG. 9 is a perspective view showing a general ferrule for an optical connector.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 ferrule 11 front end surface 12 through hole 13 outer peripheral surface 14 front end chamfered portion 15 rear end portion 16 joint portion 17 rear end chamfered portion 18 joint portion 19 joint portion 2 flange 3 spring 4 plug housing 5 optical fiber 6 mounting member 7 sleeve 8 connector Plug 9 Adapter 91 Screw 111 Outer peripheral surface 112 Concave portion 113 Grinding stone 115 Cup grinding stone for spherical surface 116 Tip R1, R2, R3 Radius of curvature

Claims (4)

[Claims] 1. A substantially cylindrical zirconia ceramic optical fiber ferrule having a through hole for accommodating an optical fiber in an axial direction, wherein a connecting portion between a through hole and a front end surface before bonding and fixing the optical fiber is provided. The radius of curvature R1 is set to 0.
A ferrule for an optical fiber, wherein a range of 0005 mm ≦ R1 ≦ 0.02 mm is satisfied. 2. A ferrule for an optical fiber made of a substantially cylindrical zirconia ceramic having a through hole for accommodating an optical fiber in an axial direction, after polishing an inner surface of the through hole, the tip surface of the ferrule is averaged. A method for processing an optical fiber ferrule, comprising a step of processing using a diamond grindstone having a diameter of 2 μm or less. 3. A ferrule for an optical fiber made of a substantially cylindrical zirconia ceramic having a through hole for accommodating an optical fiber in an axial direction, comprising a chamfered portion on an outer periphery of a tip end surface, wherein the chamfered end portion and the outer peripheral surface are formed. A ferrule for an optical fiber, characterized in that a radius of curvature R2 of the connecting portion is in a range of 0.03 mm ≦ R2 <5 mm. 4. A ferrule for an optical fiber made of substantially cylindrical zirconia ceramics having a through hole for accommodating an optical fiber in an axial direction, comprising a chamfered portion on the outer periphery of a rear end surface, and the rear end chamfered portion and the outer peripheral surface. Wherein the radius of curvature R3 at the junction between the ferrules is in the range of 0.03 mm ≦ R3 <2 mm.