JP2014061582A - Method of polishing optical fiber and polishing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of strength of an optical fiber during polishing the tip of the optical fiber.SOLUTION: A method of polishing an optical fiber comprises an exposure step of removing a part of the coating of a coated optical fiber 20 to expose the clad part 22 from the coated optical fiber 20, a cutting step of cutting the clad part 22 so as to protrude from the coating by a predetermined height, an insertion step of inserting the tip of the coated optical fiber 20 into a holding jig 11 having an insertion hole 16 allowing sliding of the coated optical fiber 20 in the circumferential direction, a step of making the clad part 22 protrude from one end surface of the holding jig 11, a polishing step of polishing the tip of the clad part 22 and a coating removal step of removing the coating of the coated optical fiber 20.

Description

  The present invention relates to an optical fiber polishing method and a polishing apparatus.

For example, a synthetic resin coating material (coating coating) is attached to the outer periphery of an optical fiber glass part (cladding part, bare optical fiber), such as an optical fiber core or an optical fiber, and is integrated. As a fiber polishing method, without removing the coating material of the optical fiber and then protecting the cladding, the optical fiber cladding is directly fixed with a gripping member, and the tip of the optical fiber is polished and processed with a laser or the like. It has been known.
Further, a method is known in which a clad portion subjected to mechanical coating removal or chemical (chemical treatment) coating is fixed with resin with paraffin, held and fixed from above, and the tip of the optical fiber is polished.

  Furthermore, as described in Patent Document 1, a method is also known in which a split sleeve is placed on a UV coating of an optical fiber, inserted into a collet chuck, and obliquely polished while being pressed and fixed.

JP 2003-311597 A

However, in the case of a method of directly fixing an optical fiber with a gripping member without protecting the clad portion, the strength of the optical fiber is deteriorated by scratching the clad portion when the optical fiber is gripped and processed. There is a problem.
Moreover, in the case of the method of fixing the resin with paraffin or the like, it is necessary to fix the paraffin before the processing and to wash the paraffin after the processing. In addition, there are problems such as defects due to the resin remaining without being washed away and scratches on the clad portion in the resin fixing and washing steps.

In the case of the method described in Patent Document 1, in order to fix the optical fiber by pressing and pressing with a collet chuck,
・ A jig with a complicated structure (collet chuck) is required.
・ It takes time to set the jig.
・ Thickness of the sleeve obstructs oblique polishing.
There are problems such as.

  The present invention has been made in consideration of such circumstances, and its purpose is not to use a jig having a complicated structure such as a collet chuck, and requires a time-consuming process such as resin fixing with paraffin. It is an object to provide an optical fiber polishing method that can prevent the strength deterioration of the optical fiber.

  In order to solve the above problems, the present invention removes a part of the coating of the coated optical fiber to expose the cladding part from the coated optical fiber, and projects the cladding part from the coating by a predetermined dimension. A cutting step of cutting in such a manner, and an insertion step of inserting the distal end portion of the coating of the coated optical fiber into a holding jig having an insertion hole that allows sliding in the circumferential direction of the coated optical fiber, A step of projecting the clad portion from one end surface of the holding jig, a polishing step of polishing the tip of the clad portion, and a coating removal step of removing the coating of the coated optical fiber. An optical fiber polishing method is provided.

  In the polishing step, it is preferable that the normal of the polishing surface of the polishing table and the axis of the cladding are intersected at a predetermined angle, and the tip of the cladding is polished obliquely.

  In the optical fiber polishing method, it is preferable to polish at least two surfaces of the tip of the clad portion by rotating the coated optical fiber about an axis.

  Further, the present invention provides a gripping member for gripping a coated optical fiber from which a part of the coating has been removed and an exposed clad portion protruding from the coating by a predetermined dimension, and the coating of the coated optical fiber A holding jig having an insertion hole that allows sliding of the coated optical fiber in the circumferential direction, and a polishing table, and the clad portion from one end surface of the holding jig. An optical fiber polishing apparatus is provided that protrudes and polishes the tip of the clad portion.

  In the optical fiber polishing apparatus, a first rotation mechanism that rotates the coated optical fiber so that an axis of the coated optical fiber intersects a normal of the polishing surface of the polishing table at a predetermined angle; And a second rotating mechanism for rotating the coated optical fiber about an axis.

  According to the present invention, when polishing the tip of the clad portion of the coated optical fiber, only the coated portion of the coated optical fiber is the holding jig except for the polished surface at the tip of the clad portion that contacts the polished surface. Since it fixes by contacting, the possibility of damaging a clad part can be reduced. By applying a predetermined amount of coating removal to the optical fiber polished by the fixing method as a post-process, it is possible to prevent the strength deterioration of the clad portion.

It is a side view of the polish device concerning the embodiment of the present invention. It is a side view which shows a mode that the grinding | polishing apparatus main body was rotated with the (theta) axis | shaft rotation mechanism. It is a side view which shows a mode that the Y2 axis | shaft operating part foundation was moved by the Y2 axis | shaft operating mechanism. It is a side view which shows a mode that the Y1 axis | shaft operating part foundation was moved by the Y1 axis | shaft operating mechanism. It is a perspective view of a holding jig. It is AA sectional drawing of FIG. It is a figure explaining the polish method using the polish device concerning the embodiment of the present invention in order. It is an enlarged view of the optical fiber front-end | tip part by the side of the grinding process hold | maintained with the holding jig. It is the graph which performed the rupture strength comparison of the coating removal part of the optical fiber processed with the grinding | polishing method of this embodiment, and the coating removal part of the optical fiber processed with the conventional grinding | polishing method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view showing the overall configuration of an optical fiber polishing apparatus 1 (hereinafter referred to as a polishing apparatus) of this embodiment. The polishing apparatus 1 of this embodiment is used in combination with a polishing table 30 (see FIG. 7), and is an apparatus for moving and rotating an optical fiber with respect to the polishing table 30.

  The optical fiber described in the present embodiment is a synthetic resin coating material (UV coating, coating coating) on the outer periphery of an optical fiber glass portion (bare optical fiber), such as an optical fiber core or an optical fiber. Is a coated optical fiber 20 having a structure in which it is deposited and integrated. In the following description, a portion where the UV coating is applied is referred to as a coating portion 21, and a portion where the UV coating is removed is referred to as a cladding portion 22.

As shown in FIG. 1, the polishing apparatus 1 holds the coated portion 21 of the coated optical fiber 20 with the fiber holder 10 (gripping member), and further inserts the distal end portion of the coated portion 21 into the holding jig 11. Thus, the coated optical fiber 20 is moved and rotated.
The polishing apparatus 1 is attached to a base part 13 of the entire polishing apparatus 1, a Y2 axis operating part base 2 connected to the base part 13 via a Y2 axis operating mechanism 12, and a Y2 axis operating part base 2. A θ-axis rotating mechanism 3 (first rotating mechanism), and a polishing apparatus that is a main body portion of the polishing apparatus 1 that is attached to the Y2-axis operating unit base 2 via the θ-axis rotating mechanism 3 so as to be rotatable about the θ-axis. And a main body 4.

  The polishing apparatus main body 4 includes a first base part 5 attached to the Y2-axis working part base 2 via the θ-axis rotation mechanism 3, a second base part 6 fixed on the first base part 5, A Y1 axis operating part base 7 movably attached to the two base parts 6 in a predetermined direction; a φ axis rotating mechanism 8 (second rotating mechanism) installed on the Y1 axis operating part base 7; A fiber holder 10 attached to the φ-axis rotation mechanism 8 and a holding jig 11 fixed to the second base portion 6 are provided as main components.

  The θ-axis rotating mechanism 3 is attached to the Y2-axis operating part base 2 and a plate-like first base part 5 provided in parallel with one surface of the Y2-axis operating part base 2 is set to the central axis C by an electric motor (not shown). It is a mechanism that rotates around. That is, as shown in FIG. 2, the first base portion 5 that forms the basis of the polishing apparatus main body 4 is rotated around the central axis C orthogonal to one surface of the first base portion 5 by the θ-axis rotating mechanism 3. As a result, the second base portion 6 attached to the first base portion 5, the φ-axis rotation mechanism 8, the coated optical fiber 20 held by the fiber holder 10 and the like rotate together with the first base portion 5. To do.

  The second base portion 6 is a plate-like member installed so as to be orthogonal to the first base portion 5 and is attached to the first base portion 5. A fixing tool 24 is provided at one end of the second base portion 6 via a stay 14, and the holding jig 11 into which the covering portion 21 of the coated optical fiber 20 is inserted into the fixing tool 24. Is fixed. The detailed shape of the holding jig 11 will be described later.

  The Y2 axis operating mechanism 12 is composed of a ball screw, a linear motion guide (linear motion bearing, linear guide), and the like, and is a mechanism that moves the Y2 axis operating portion foundation 2 in the horizontal direction. That is, as shown in FIG. 3, the Y2 axis operating mechanism 12 causes the Y2 axis operating part base 2 and the polishing apparatus main body 4 attached to the Y2 axis operating part base 2 via the θ axis rotating mechanism 3 to Move in the direction.

  The Y1-axis operating part base 7 is a plate-like member provided in parallel with the second base part 6, and is attached to the second base part 6 via the Y1-axis operating mechanism 15. The Y1-axis operating mechanism 15 is composed of a ball screw and a linear guide, like the Y2-axis operating mechanism 12, and is a mechanism for moving the Y1-axis operating part base 7 in a predetermined direction. That is, as shown in FIG. 4, the Y1-axis operating mechanism 15 causes the Y1-axis operating part base 7, the φ-axis rotating mechanism 8, the coated optical fiber 20 held by the fiber holder 10, and the like to the second base part. 6 moves in a predetermined direction.

When the Y1 axis operating part base 7 is moved by the Y1 axis operating mechanism 15,
The distance between the holding jig 11 which is relatively immovable from the second base portion 6 and the fiber holder 10 changes.

  The φ-axis rotation mechanism 8 is provided on the other side of the Y1-axis operation unit base 7. The φ-axis rotating mechanism 8 is configured by a stepping motor or the like, and a rotating shaft 9 extending in a direction along the predetermined direction Y is attached. A fiber holder 10 is attached to the rotating shaft 9. Here, the fiber holder 10 and the rotary shaft 9 are in such a positional relationship that the central axis of the optical fiber held by the fiber holder 10 coincides with the central axis of the rotary shaft 9 of the φ-axis rotating mechanism 8. Is arranged.

  Further, the optical fiber is held such that the tip portion of the clad portion 22 slightly protrudes from the holding jig 11. The holding jig 11 is arranged such that the tip of the optical fiber is positioned on the rotation center axis of the θ-axis rotation mechanism 3.

Next, the holding jig 11 will be described.
As shown in FIG. 5, the holding jig 11 has a cylindrical shape in which a fiber insertion hole 16 having a circular cross section through which the clad portion 22 of the optical fiber is inserted is formed on the central axis. The holding jig 11 is made of ceramic such as zirconia, for example.
As a material for forming the holding jig 11, for example, engineering plastics such as PEEK resin can be adopted, but zirconia is most preferable from the viewpoint of ensuring processing accuracy when the fiber insertion hole 16 is processed. In addition, as a material for forming the holding jig 11, metal, glass, or the like can be used.

  As will be described later, the optical fiber coating portion 21 is inserted into the holding jig 11, but the side on which the optical fiber is inserted is called the other side, and the side from which the tip of the inserted optical fiber protrudes. Is called one side. The fiber insertion hole 16 is formed from the center of the end face on one side in the axial direction of the holding jig 11 to the center of the end face on the other side.

As shown in FIG. 6, the inner diameter of the fiber insertion hole 16 is formed so that one side is thin and the other side is thick. Specifically, one side of the fiber insertion hole 16 is a coating holding portion 17, and the inner diameter thereof is, for example, about 260 μm to 280 μm with respect to the coating portion 21 having a diameter of 250 μm.
More specifically, the coating holding part 17 has an inner diameter that suppresses the gap with the coating part 21 to 50 μm or less. For example, when the diameter of the covering portion 21 is 245 ± 15 μm, the minimum value of the covering portion 21 is 230 μm, and when the inner diameter of the covering holding portion 17 is 280 μm, a gap formed between the covering holding portion 17 and the covering portion 21. Is 50 μm. By setting the inner diameter of the coating holding portion 17 in this way, the coated optical fiber 20 is allowed to slide in the circumferential direction during the polishing of the optical fiber, and the processing accuracy is prevented from being deteriorated due to the optical fiber violating. can do.

The other side of the fiber insertion hole 16 is a diameter-expanded portion 18 that is expanded with respect to the coating holding portion 17, and the inner diameter of the diameter-expanded portion 18 is about 500 μm. That is, the inner diameter of the enlarged diameter portion 18 is about twice the diameter of the covering portion 21.
Further, at the boundary portion between the coating holding portion 17 and the enlarged diameter portion 18, the inner diameter of the fiber insertion hole 16 is gradually increased from one side toward the other side.

A chamfer 19 is formed on one side of the holding jig 11. As shown in FIG. 6, the chamfer 19 has a cross-sectional shape including the central axis of the holding jig 11, and the height of the holding jig 11 is one end face from a predetermined position in the axial direction of the holding jig 11. It is formed so that its height gradually decreases toward the. In other words, a flat surface is formed at one end of the holding jig 11 so that a part of a circular slope formed by the one end face of the holding jig 11 and the outer peripheral surface of the holding jig 11 is cut. Is formed.
The wedge shape that can be processed by the polishing apparatus 1 is limited by the angle of the chamfered portion 19 of the holding jig 11. That is, a wedge-shaped shape having a steeper angle than the angle of the chamfered portion 19 cannot be produced.

Next, the operation of the polishing apparatus 1 according to this embodiment will be described.
The polishing apparatus 1 is an apparatus that freely abuts the tip of the optical fiber against polishing paper provided on the polishing surface 30 a of the polishing table 30. The polishing apparatus 1 has a function of gripping the coated optical fiber 20, and the polishing table 30. The function of tilting the coated optical fiber 20 (θ-axis rotation), the function of rotating the coated optical fiber 20 about its axis (φ-axis rotation), and moving the coated optical fiber 20 toward the polishing table 30 A function (Y2-axis movement) and a function of inserting the optical fiber tip through the holding jig 11 (Y1-axis movement).

Next, a polishing method using the polishing apparatus 1 according to this embodiment will be described.
First, the coated optical fiber 20 is set in the polishing apparatus 1. That is, as shown in FIG. 7A, the coated portion 21 of the coated optical fiber 20 is held by the fiber holder 10. Next, using a predetermined coating removal apparatus (not shown), the UV coating of the coated optical fiber 20 is removed to expose the cladding 22 (exposure process).

  Here, the diameter of the covering portion 21 of the coated optical fiber 20 is about 250 μm, and the diameter of the cladding portion 22 is about 125 μm. The coating removal apparatus has a blade whose inner diameter is larger than the outer diameter of the cladding portion 22 and smaller than the outer diameter of the coating portion 21. In this process, only the UV coating is peeled off from the coated optical fiber 20 by using the coating removing apparatus having the blade.

Next, as shown in FIG. 7B, the clad portion 22 of the coated optical fiber 20 is cut to lead the clad portion 22 from the cover portion 21 to an appropriate length (cutting step). That is, the cladding part 22 is cut so as to protrude from the covering part 21 by a predetermined dimension.
As in this embodiment, when the diameter of the covering portion 21 of the coated optical fiber 20 is about 250 μm and the diameter of the cladding portion 22 is about 125 μm, the lead length is suitably 0.2 to 0.5 mm. .

  Here, in order to ensure the strength of the clad part 22, it is necessary that the clad part 22 other than the cut part is not in contact with a cutting tool or the like. For example, after applying tension to the coated optical fiber 20, it is preferable to perform cutting by high-strength fusion in which a flaw is formed by cutting with a blade from the side or cutting with a laser.

  Next, as shown in FIG. 7C, the coated optical fiber 20 is moved using the Y1-axis operating mechanism 15, and the coated portion 21 is inserted into the fiber insertion hole 16 of the holding jig 11 (insertion step). At this time, as shown in FIG. 8, alignment is performed so that the tip of the covering portion 21 protrudes from the tip (one end surface) of the holding jig 11 by a predetermined dimension. This is because the clad portion 22 does not come into contact with the holding jig 11, and if the protruding amount is larger than a predetermined dimension, the lead clad portion 22 is not suitable because it is bent.

  Further, the optimum amount of protrusion differs depending on the angle at which the surface to be polished at the tip of the clad portion 22 is shaved in a polishing step described later. For example, when the cutting angle is an obtuse angle of 45 ° or less, a protrusion amount of 300 μm to 400 μm can be handled. On the other hand, for example, when the angle is an acute angle close to the chamfered portion 19 shown in FIG. 8, it is necessary to protrude 500 μm or more to avoid interference between the holding jig 11 and the polishing table 30.

  A predetermined gap is generated between the outer peripheral surface of the covering portion 21 of the coated optical fiber 20 and the inner peripheral surface of the covering holding portion 17 of the holding jig 11. Specifically, a gap of 50 μm or less is generated. That is, during polishing, the outer peripheral surface of the covering portion 21 of the coated optical fiber 20 is fixed by friction by contacting with the inner peripheral surface of the holding jig 11 with an appropriate pressure. Further, when there is no contact with the polished surface, there is a predetermined gap between the outer peripheral surface of the covering portion 21 of the coated optical fiber 20 and the inner peripheral surface of the covering holding portion 17 of the holding jig 11. The optical fiber 20 can be rotated about the axis.

  Next, as shown in FIG. 7 (d), the coated optical fiber 20 and the holding jig 11 are moved using the Y2 axis operating mechanism 12, and the surface to be polished at the tip of the cladding portion 22 is polished on the polishing surface of the polishing table 30. The tip of the optical fiber is polished by being brought into contact with 30a (polishing step). Here, if necessary, oblique polishing can be performed by changing the angle of the coated optical fiber 20 with respect to the polishing surface 30a of the polishing table 30 using the θ-axis rotating mechanism 3. That is, the front end of the cladding portion 22 can be polished obliquely by intersecting the normal line of the polishing surface 30a and the axis of the cladding portion 22 at a predetermined angle.

  Further, if necessary, the coated optical fiber 20 is rotated around the axis of the coated optical fiber 20 by using the φ-axis rotating mechanism 8 to polish the side opposite to the side polished by the polishing step. Can do. That is, by operating the φ axis rotation mechanism 8 and rotating the clad portion 22 held by the holding jig 11 in the holding jig 11, at least two surfaces at the tip of the clad portion 22 can be polished.

  Then, as shown in FIG. 7E, the UV coating is removed so that the coated optical fiber 20 whose tip has been polished is in a form suitable for the final application (coating removal step). Specifically, for example, the UV coating is removed so as to be in a form suitable for assembly to a laser emission unit (package).

At the tip of the optical fiber, the ridge line where the core is located is formed by polishing, electric discharge machining, or laser processing on the tip of the optical fiber where the core of the optical fiber is positioned on the ridge line and both sides of the ridge line are obliquely polished. The curvature suitable for the application shall be provided.
Through the above steps, the tip of the optical fiber can be processed into a shape for efficient spatial coupling with, for example, an LD element.

  Next, in order to confirm the tensile strength of the coated optical fiber manufactured using the optical fiber polishing method according to the present embodiment, a tensile test was performed together with the conventional coated optical fiber. In the tensile test, the tip of the clad portion 22 of the coated optical fiber 20 was fixed to a fixing jig via a fixing resin, and then tension was applied to the coated optical fiber 20 in a direction away from the fixing jig.

  A Weibull plot for the breaking strength of each coated optical fiber is shown in FIG. The horizontal axis of the graph is the breaking strength, and the vertical axis is the logarithm of the failure probability.

  As shown in FIG. 9, the coating removal portion of the optical fiber subjected to the polishing process of the present embodiment has a strength about four times or more than the coating removal portion of the optical fiber subjected to the conventional polishing process.

  According to the above-described embodiment, when the tip of the cladding portion 22 of the coated optical fiber 20 is polished, the coated portion of the coated optical fiber 20 is excluded except for the polished surface at the tip of the cladding portion 22 that contacts the polishing surface 30a. Since only 21 is fixed in contact with the holding jig 11, the possibility of damaging the clad portion 22 can be reduced, and strength deterioration can be prevented. That is, since the final UV coating is removed after the polishing process of the optical fiber tip, it is possible to prevent the strength deterioration of the clad portion 22.

Further, since the chamfered portion 19 is formed on the holding jig 11, the polished surface does not interfere with the holding jig 11 even when performing oblique polishing.
In addition, when removing the UV coating, the blade does not touch the clad portion 22, so that strength deterioration of the clad portion 22 can be prevented.
Further, the holding of the coating portion 21 of the coated optical fiber 20 by the holding jig 11 is only to insert the coating portion 21 into the fiber insertion hole 16 of the holding jig 11. Can be shortened. In particular, when the tip of the optical fiber has a special shape, it is necessary to change the direction of the optical fiber a plurality of times during polishing, but the direction can be changed by simply rotating.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the embodiment described above, the chamfered portion 19 of the holding jig 11 is a flat surface. However, the tip of the holding jig 11 may be formed in a conical shape in the circumferential direction instead of a flat surface.
Moreover, in the said embodiment, although the diameter of the coating | coated part 21 of the coated optical fiber 20 was 250 micrometers, the diameter of the coating | coated part 21 is not limited to this. Similarly, the diameter of the clad portion 22 is not limited to 125 μm, and therefore the lead length is not limited to 0.2 to 0.5 mm.

DESCRIPTION OF SYMBOLS 1 ... Polishing apparatus 2 ... Y2 axis | shaft operation part foundation 3 ... (theta) axis | shaft rotation mechanism 4 ... Polishing apparatus main body 5 ... 1st base part 6 ... 2nd base part 7 ... Y1 axis | shaft operation part foundation 8 ... φ axis rotation mechanism 10 ... Fiber Holder 11 ... Holding jig 12 ... Y2 axis operating mechanism 13 ... Foundation part 14 ... Stay 15 ... Y1 axis operating mechanism 16 ... Fiber insertion hole 17 ... Cover holding part 19 ... Chamfered part 20 ... Covered optical fiber 21 ... Covering part 22 ... Clad part 30 ... Polishing table 30a ... Polished surface

Claims (5)

An exposure step of removing a portion of the coating of the coated optical fiber to expose the cladding from the coated optical fiber;
A cutting step of cutting the clad portion so as to protrude a predetermined dimension from the coating;
An insertion step of inserting the tip of the coating of the coated optical fiber into a holding jig having an insertion hole that allows sliding of the coated optical fiber in the circumferential direction;
Projecting the clad part from one end face of the holding jig;
A polishing step of polishing the tip of the cladding part;
A coating removing step of removing the coating of the coated optical fiber.   2. The light according to claim 1, wherein in the polishing step, the normal of the polishing surface of the polishing table and the axis of the cladding are intersected at a predetermined angle, and the tip of the cladding is polished obliquely. Fiber polishing method.   The optical fiber polishing method according to claim 2, wherein at least two surfaces of the tip of the clad portion are polished by rotating the coated optical fiber around an axis. A gripping member for gripping the coated optical fiber, wherein a part of the coating is removed, and the exposed clad portion is cut so as to protrude a predetermined dimension from the coating;
A holding jig having an insertion hole for allowing the coating optical fiber coating to slide in the circumferential direction of the coated optical fiber; and
A polishing table,
An optical fiber polishing apparatus characterized by polishing the tip of the clad part by projecting the clad part from one end surface of the holding jig. A first rotation mechanism for rotating the coated optical fiber so that the axis of the coated optical fiber intersects the normal of the polishing surface of the polishing table at a predetermined angle;
The optical fiber polishing apparatus according to claim 4, further comprising: a second rotation mechanism that rotates the coated optical fiber about an axis.

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