JP3906097B2 - Ferrule for optical fiber - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention is used for optical communication or the like, and relates to the optical fiber ferrule.
[0002]
[Prior art]
Conventionally, an optical fiber ferrule for fixing an optical fiber used for optical signal processing such as optical communication is an optical connector used for connecting optical fibers or a semiconductor laser composed of a semiconductor laser and an optical fiber, etc. Used for modules.
[0003]
For example, as shown in the side view of FIG. 4, the optical connector is formed by inserting a single mode optical fiber made of quartz into a through-hole 24 of an optical fiber ferrule 21 made of zirconia ceramics (hereinafter referred to as a ferrule) and bonding and fixing it. The chamfered portion 22 and the tip portion 23 polished to a spherical portion continuous to the chamfered portion are inserted into the split sleeve 14 made of phosphor bronze or the like and brought into contact with the tip portion 23 of another ferrule 21 for optical connection. It is a mechanism to do.
[0004]
In the ferrule 21, a chamfered portion 22 is formed on the outer periphery of the distal end portion 23 in order to improve the insertability into the split sleeve 14.
[0005]
As shown in FIG. 5, the chamfered portion 22 of the ferrule 21 rotates a cylindrical ceramic body 27 that becomes the ferrule 21, and a cylindrical diamond grindstone 31 is attached to the tip of the cylindrical ceramic body 27 with respect to the axial direction of the cylindrical ceramic body 27. Polishing is performed by bringing the angle θ into contact by rotating at an angle of 20 to 60 °, and the chamfered portion 22 of the obtained ferrule 21 has a truncated cone shape, and a tool mark 22A which is a grinding mark of the grindstone 31 is formed. It was formed at right angles to the axial direction.
[0006]
[Problems to be solved by the invention]
In the conventional optical fiber ferrule 21, the tip 23 is formed by a processing method as shown in FIG. 4, so that tool marks 22 </ b> A are formed at right angles to the axial direction. Therefore, when used as an optical connector, for example, when inserted into the split sleeve 14 made of phosphor bronze or the like and brought into contact with the tip of another ferrule, the split sleeve 14 is damaged by the tool mark 22A, and the ferrule 21 The black shavings of the split sleeve 14 are adhered to the outer peripheral surface of the optical fiber, and the shavings are also adhered to the tip surface of the optical fiber. Further, repeated insertion / extraction deteriorates the cylindricity and straightness of the split sleeve 14 and has a disadvantage that the connection loss is not stable.
[0007]
[Means for Solving the Problems]
In view of the above, the ferrule for an optical fiber of the present invention is a cylindrical ceramic optical fiber ferrule having a through hole for accommodating the optical fiber in the axial direction of the ferrule,
The tip of the ferrule has a frustoconical chamfer formed on the outer periphery, and the chamfer
It has a continuous spherical section, and is characterized in that the tool marks chamfered portion is substantially formed parallel to the axial direction.
[0010]
According to the ferrule for an optical fiber of the present invention, since the frustoconical chamfered portion is formed on the outer periphery of the tip portion, and the tool mark of the chamfered portion is formed substantially parallel to the axial direction, Since the direction to insert into the split sleeve and the direction of the tool mark on the chamfer are the same direction, the split sleeve can be inserted smoothly and accurately without shaving, connection loss can be reduced, and repeated mounting Even at times, it is possible to effectively prevent cracks and scratches from occurring in the split sleeve.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a side view showing an embodiment of an optical connector ferrule 1 (hereinafter referred to as ferrule 1) according to the present invention.
[0015]
In the ferrule 1 of the present invention, a through-hole 4 for accommodating an optical fiber is formed in the axial direction B, and the tip 3 is a substantially convex spherical surface composed of a chamfered portion 2 and a spherical portion continuous to the chamfered portion 2. have. On the other hand, an optical fiber insertion portion 5 having a truncated cone shape is formed at the rear end portion 6.
[0016]
The chamfered portion 2 has a truncated cone shape having a certain taper, and it is important that the tool mark 2A is formed substantially parallel to the axial direction of the ferrule .
[0017]
The tool mark 2A indicates a grinding mark of a grindstone used when the chamfered portion 2 of the ferrule 1 is processed.
[0018]
When the ferrule 1 is used as an optical connector, the tool mark 2A of the chamfered portion 2 has the same direction as the tool mark 2A of the chamfered portion 2 and the direction of insertion into the split sleeve from the tip portion 3. It can be inserted smoothly and accurately without shaving, and the connection loss can be reduced.
[0021]
In addition, it is preferable that the bus-line B of the said chamfer part 2, ie, a taper angle, shall be 20-60 degrees, and when inserting the ferrule 1 in a split sleeve, it can insert smoothly. If the taper angle is less than 20 ° or exceeds 60 °, there is a possibility that the taper will be caught once during the insertion and adversely affect the ferrule 1, the split sleeve, and the housing of the optical connector.
[0022]
The material forming the ferrule 1 is made of ceramics such as zirconia, alumina, silicon nitride, silicon carbide, etc., and it is particularly preferable to use ceramics mainly composed of zirconia.
[0023]
Specifically, ZrO ₂ as a main component and a stabilizer containing one or more of Y ₂ O ₃ , MgO, CaO, CeO ₂ , Dy ₂ O _{3 and the} like, and a portion mainly composed of tetragonal crystals Stabilized zirconia ceramics are used. Moreover, when manufacturing the ferrule 1 which consists of such zirconia ceramics, it is obtained by using the above-mentioned raw material powder, forming it into a predetermined shape by extrusion molding, injection molding, press molding or the like and then firing it.
[0024]
As this 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, when the average crystal grain size exceeds 1.0 μm, voids between the crystals become large and a good outer peripheral surface cannot be obtained, and the particle size is stably reduced to 0.1 μm or less when pulverizing with a ball mill or the like when mixing raw materials. It is difficult to adjust, and after firing, the crystal grows and the diameter further increases. The porosity represents the percentage of voids contained in the ferrule 1 as a percentage. When the porosity exceeds 3%, the pore portion deteriorates the surface roughness.
[0025]
This ferrule 1 can be applied to both single mode and multimode.
[0026]
Next, a method for processing the chamfered portion 2 of the ferrule for optical fiber of the present invention will be described with reference to FIG.
[0027]
FIG. 2A is a schematic front view of an apparatus showing a method for processing the ferrule 1.
[0028]
First, a plurality of cylindrical ceramic bodies 7 made of a predetermined ceramic raw material to be the ferrule 1 and having a hole to be the through hole 4 are fixed in a groove formed on the outer peripheral side of the carrier 8, and the carrier 8 is rotated.
[0029]
A belt 10 is provided below the carrier 8, and the belt 10 is attached to a fixed fulcrum 9 outside the carrier 8 and functions to hold and rotate the cylindrical ceramic body 7. The diamond grindstone 11 is an R-shaped diamond grindstone, which is processed by being rotated by a drive shaft perpendicular to the axial direction of the cylindrical ceramic body 7.
[0030]
FIG. 2B is a partial front view of the carrier 8.
[0031]
The carrier 8 has a groove for holding the cylindrical ceramic body 7, and the cylindrical ceramic body 7 is continuously supplied to the carrier 8 to carry it to the processing position.
[0032]
The cylindrical ceramic body 7 is rotated by a moving wheel 13 and is fixed by a belt 10 to prevent slipping. The cylindrical ceramic body 7 is in contact with the belt 10. The width of the belt 10 is the same as or narrower than that of the carrier 8.
[0033]
FIG. 3C is a partial side view of the carrier 8.
[0034]
There is a driving wheel 13 inside the carrier 8, and the carrier 8 and the driving wheel 13 are coaxially rotated. By rotating the carrier 8 slower than the driving wheel 13, the belt is rotated while the cylindrical ceramic body 7 is rotated. The cylindrical ceramic body 7 is held by 10.
[0035]
FIG. 4D is a side view of FIG.
[0036]
The cylindrical ceramic body 7 moves to the lower part of the carrier 8 and comes into contact with the diamond grindstone 11 rotated by a drive shaft perpendicular to the axial direction. This contacted grinding point 12 determines the angle of the generatrix B of the chamfer 2 of the ferrule 1. This is because the diamond grindstone 11 is very large with respect to the size of the chamfered portion 2 of the cylindrical ceramic body 7, and the approximate tangent of the diamond grindstone 11 forms the chamfered portion 2, so that the ferrule depends on the position of the grinding point 12. The angle of the generatrix B of the chamfered portion 2 of 1 is determined. By this processing, the tool mark 2A is formed in the chamfered portion 2 of the obtained ferrule 1 in parallel with the axial direction of the chamfered portion 2.
[0037]
When the ferrule 1 obtained in this way is used as an optical connector, the direction in which the ferrule 1 is inserted into the split sleeve from the tip 3 and the direction of the tool mark 2A of the chamfer 2 are the same direction. Therefore, it is possible to smoothly and accurately insert the optical fiber of the other ferrule inserted from the opposite side of the split sleeve, and to reduce the connection loss with the optical fiber of the other ferrule. Further, even during repeated mounting, the split sleeve does not become chipped or scratched, and the increase in connection loss can be reduced.
[0038]
In addition, the ferrule for optical fibers of this invention is not limited to the above-mentioned embodiment, A various change is possible if it is a range which does not deviate from the summary of this invention.
[0039]
【Example】
Next, examples of the present invention will be described.
[0040]
A sample made of zirconia ceramics as shown in FIG. 1 and having a chamfered tool mark formed parallel to the axial direction of the ferrule, and as a conventional example, a tool mark as shown in FIG. 4 was formed perpendicular to the axial direction. Ten samples were prepared for each, and the connection loss value before and after the test was confirmed by repeatedly inserting and removing 100 times.
[0041]
The ferrule sample had an outer diameter D = φ2.5 mm, a length L = 10.5 mm, a through hole d = φ0.126 mm, and a radius of curvature of the final polishing finish at the tip was 18 mm.
[0042]
The result is shown in FIG.
[0043]
In addition, the value in FIG. 3 is an average value of ten pieces.
[0044]
From the result of FIG. 3, the sample in which the tool mark of the chamfered portion, which is a conventional example, is formed at right angles to the axial direction of the ferrule, scratches the split sleeve, and the shavings adhere to the ferrule, resulting in connection loss. Deteriorate to about 0.6 dB.
[0045]
On the other hand, a sample in which the tool mark of the chamfered part is formed substantially parallel to the axial direction of the ferrule can obtain stable insertion without damaging the split sleeve, and the connection loss is as small as 0.2 dB or less. I knew it was possible.
[0046]
【The invention's effect】
According to the ferrule for an optical fiber of the present invention, the tip of the ferrule has a frustoconical chamfered portion formed on the outer periphery and a spherical portion continuous to the chamfered portion. since the tool mark is substantially formed parallel to the axial direction, since the direction of the tool mark direction and the chamfered portion for inserting a ferrule into the split sleeve in the same direction, without cutting the split sleeve, It can be inserted smoothly and accurately, the connection loss can be reduced, and it is possible to effectively prevent the split sleeve from being cracked or scratched even during repeated mounting.
[Brief description of the drawings]
FIG. 1 is a side view showing an embodiment of an optical fiber ferrule of the present invention.
FIGS. 2A to 2D are explanatory views showing a method for processing a ferrule for an optical fiber according to the present invention.
FIG. 3 is a diagram showing results of repeated insertion / extraction tests.
FIG. 4 is a side view showing a conventional ferrule for an optical fiber.
FIG. 5 is a schematic view showing a conventional method for processing a ferrule for an optical fiber.
[Explanation of symbols]
1: Ferrule 2: Chamfered portion 2A: Tool mark 3: Tip portion 4: Through hole 5: Optical fiber insertion portion 6: Rear end portion 7: Columnar ceramic body 8: Carrier 9: Fixed fulcrum 10: Belt 11: Diamond grindstone 12: Grinding point 13: Driving wheel 14: Split sleeve

Claims (1)

A cylindrical ceramic optical fiber ferrule having a through hole for accommodating an optical fiber in the axial direction of the ferrule,
The tip of the ferrule has a frustoconical chamfer formed on the outer periphery, and the chamfer
A ferrule for an optical fiber, characterized in that the tool mark of the chamfered portion is formed substantially parallel to the axial direction.

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