JP2005241809A - Tip section machining device of optical fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical fiber tip section machining device which is used to simply and economically polish an optical fiber whose tip section has an elliptic tapered shape. <P>SOLUTION: The optical fiber tip section machining device is provided with a fixture having a first through-hole which is used to hold and fix the optical fiber and a second through-hole in which the size is made greater than the first through-hole and the tip section of the optical fiber is projected from one of the openings that are formed into elliptic shapes and a polishing member which is used to polish the tip section of the optical fiber. The tip section of the optical fiber is bent so that the section makes an acute angle with respect to the surface of the polishing member and is rotated on the surface of the polishing member in a sliding manner. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical fiber tip portion processing apparatus for processing a tip portion of an optical fiber into an elliptic taper shape.

  As a light source for optical communication, a laser diode (hereinafter referred to as LD) is used. In general, it is known that the pattern of light emitted from the LD is not a concentric Gaussian distribution in the emission direction but an elliptical beam shape that differs in the vertical and horizontal directions. As a typical example, an LD having a wavelength of 980 nm has a pattern of outgoing light having an aspect ratio of 2 to 4: 1. The coupling between an LD having such a large aspect ratio and an optical fiber also includes an optical fiber tip. An optical fiber having a tip shape corresponding to the LD aspect ratio is suitable. In general, a wedge fiber having a wedge-shaped tip at the end of the optical fiber is effective.

  In this wedge fiber, the inclination angle of the tip and the radius of curvature of the tip corresponding to each spot size have been selected for the purpose of efficient condensing by changing the coupling efficiency depending on the spot size of the LD.

  An example of a conventional wedge fiber is shown in FIG. Fig.5 (a) is a front view in the front-end | tip part of the conventional wedge fiber, FIG.5 (b) is the side view. A conventional wedge fiber 10 has a pair of symmetrical edges with respect to a center axis (hereinafter simply referred to as a center axis) 3 that is the center of the core of the optical fiber 1 and the outer diameter of the optical fiber, and forms a sharp ridgeline at the tip of the optical fiber. The lens 11 which consists of the inclined surface 11a is provided.

  Another wedge fiber is shown in FIG. The wedge fiber 20 is provided with a pair of inclined surfaces 11a symmetrical with respect to the central axis 3 of the optical fiber 1 to form a wedge shape, and a semi-cylindrical curved surface 22 is continuously formed with respect to these inclined surfaces to form a lens. (See Patent Document 1).

  Another wedge fiber is shown in FIG. This wedge fiber 30 is composed of two inclined surfaces 11a symmetrical with respect to the central axis 3 of the optical fiber 1 and a plane portion 32 perpendicular to the central axis 3 of the optical fiber 1 at the tip of the optical fiber. A lens having an angle θ between 10 ° and 70 ° formed between the inclined surface 11a and the vertical plane portion 32 is formed (see Patent Document 2).

  Conventionally, such a method for producing the wedge fibers 10 to 30 has been formed using a jig shown in FIGS. That is, first, the fixing jig 98 is fixed to the distal end side of the optical fiber 1, and the angle formed between the surface of the optical fiber 1 on the flat polishing disk 2 and the central axis 3 of the optical fiber 1 is θ. Abutting and polishing while maintaining the angle θ. Thereby, the inclined surface 11 a is formed on one side of the tip of the optical fiber 1. Next, in order to create the inclined surface 11a of the optical fiber on the opposite side of 180 degrees, the fixing jig 98 is inverted and set again while the optical fiber 1 is fixed to the fixing jig 98, and the polishing operation is similarly performed. .

  Next, when the curved surface 22 is provided at the tip portion like the wedge fiber 20, the tip portion is melted by electric discharge machining to form a semi-cylindrical curved surface 22 as described in Patent Document 3. Specifically, an optical fiber processed into a wedge shape is arranged between electrodes, the discharge time and discharge intensity are set to control the melting amount of the optical fiber 1, and a semi-cylindrical shape having a desired radius of curvature at the tip ridge line portion 22 is formed. The processing of the semi-cylindrical curved surface 22 by melting can easily perform highly accurate curved surface processing by controlling the discharge time and the discharge intensity. Moreover, the process of the semi-cylindrical curved surface 22 by melting can form the inclined surface 11a and the semi-cylindrical curved surface 22 into a continuous curved surface.

However, in the case of the creation method by the conventional method,
When laser light is incident on the optical fiber, the deviation between the center X of the tip end of the optical fiber after polishing and the center axis 3 of the optical fiber 1 must be 1 μm or less because the connection loss is deteriorated. Therefore, the tip of the optical fiber 1 is polished to some extent by a polishing apparatus, and then the optical fiber 1 is removed from the polishing apparatus to confirm the polishing accuracy.

  For this reason, even if the optical fiber 1 is attached to the polishing apparatus again after polishing and polishing is performed, the polishing positioning is difficult, and there is a problem that the polishing accuracy deteriorates due to variations in the mounting position.

  Moreover, there is a problem in that the yield is poor when the optical fiber 1 is frequently removed and the optical fiber 1 is damaged or broken. Furthermore, there is a problem that the polishing time and the polishing work are increased by repeating the attachment and detachment to confirm the polishing accuracy.

As a method for solving the above problem, by polishing while checking the polishing state by conducting the inspection light to the optical fiber and detecting the return light of the inspection light while polishing the tip of the optical fiber. It has also been proposed to increase processing accuracy (see Patent Document 4).
JP-A-8-86923 Japanese Patent Laid-Open No. 10-307230 JP 2002-228857 A JP 2003-117792 A

  However, even in the case of the improved production method, it is necessary to remove the optical fiber 1 once in the process of producing two inclined surfaces by polishing as in the conventional method, and the optical fiber 1 is used for detecting return light. Since it is necessary to deposit a metal film on the tip, the structure is complicated, and it is necessary to prepare a separate device for detecting the return light, which is not necessarily suitable for mass production.

  In view of the above, the optical fiber tip processing apparatus according to the present invention includes a first through hole that holds and fixes an optical fiber, and one opening that is larger than the first through hole and has an elliptical shape. A fixing jig having a second through hole formed by projecting the tip of the optical fiber, and a polishing disc for polishing the tip of the optical fiber, the tip of the optical fiber having an acute angle with respect to the surface of the polishing disc The surface of the polishing board is slid and rotated in a state of being bent as described above.

  According to the configuration of the present invention, when the tip of the optical fiber is slid and rotated in a state where the tip of the optical fiber is bent at an acute angle with respect to the surface of the polishing disc, the outer peripheral portion of the tip of the optical fiber Not only in contact with the polishing surface, but also due to the elliptical opening, the distance from the central axis of the optical fiber of the first through hole to the elliptical opening is periodic during one revolution of the surface of the polishing disk. Therefore, the outer periphery of the tip end portion of the optical fiber does not uniformly contact the polishing surface, and the polishing angle and the polishing amount can be shaped corresponding to the elliptical period.

  Therefore, it is possible to process the tip of the optical fiber into an elliptical taper shape by simply setting it once without removing and fixing the fixing jig for polishing the optical fiber in the middle of the process. The end of the optical fiber can be processed with high accuracy without the need for an optical fiber.

  Further, since the optical fiber is not frequently removed during the polishing process, there is no problem that the optical fiber is damaged or broken during handling.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a view showing an optical fiber fixing jig used in the optical fiber tip processing apparatus of the present invention. FIG. 1 (a) shows a side view of a state where an optical fiber is mounted, FIG. 1 (b) shows a bottom view thereof, and FIG. 1 (c) is a cross section showing a state when the optical fiber is polished. The figure is shown.

  The fixing jig 9 is supported by an optical fiber fixing portion 93 having a first through hole 91 for holding the optical fiber 1 in a sandwiched manner, and the optical fiber 1 in an oblique contact with the optical fiber 1 bent at a lower portion thereof. And an optical fiber support portion 94 having a second through hole 92 larger than the first through hole 91. Since the second through-hole 92 processes the tip of the optical fiber 1 into an elliptical taper shape, the gap 95 has an elliptical cross section.

  The optical fiber 1 is attached to the fixing jig 9, and the fixing jig 9 is rotated in the circumferential direction in a state where the tip of the optical fiber 1 protruding from the opening of the second through hole 92 is brought into contact with the polishing surface 21 and is bent. Then, the tip of the optical fiber slides and rotates with respect to the polishing surface 21. At this time, the side surface of the optical fiber 1 rotates together with the fixing jig 9 while being a monk on the elliptical support portion 92a on the side opposite to the rotation direction of the optical fiber support 94. Specifically, the distance from the central axis 3 of the optical fiber 1 fixed to the optical fiber fixing portion 93 to the support portion 93 is periodically changed during one rotation by the elliptical support portion 92a. The outer periphery of the tip of the fiber 1 does not uniformly contact the polishing surface, and the polishing angle and the polishing amount have a shape corresponding to the elliptical period.

  As a result, the end of the polished optical fiber has an elliptical end surface as shown in FIG. The tip portion of the optical fiber thus created has the same function as the optical fiber 1 described with reference to FIGS.

  At this time, the polishing angle of the tip of the optical fiber 1 is determined by the contact angle θ with the polishing surface, and the polishing amount is determined by the contact pressure and the contact area with the polishing surface. Specifically, the polishing angle and the polishing amount are the shortest distance from the central axis 3 of the optical fiber 1 where the optical fiber is fixed to the fixing portion 93 to the support portion 92a, the height from the support portion 92a to the polishing surface 21, the light It is determined by the length from the first through hole 91 of the fiber 1 to the tip of the optical fiber, the rigidity of the optical fiber, the rotational speed of the fixing jig, and the coefficient of friction between the optical fiber and the polished surface.

  If it is made using such an apparatus, it is not necessary to remove the optical fiber once in the middle of the production, and it is said that the yield is poor when the optical fiber is damaged or broken by frequently removing the optical fiber. There is no problem. In addition, the polishing itself is performed in an axially symmetrical manner around the optical axis center of the optical fiber. Therefore, in principle, the tip of the optical fiber is compared with the conventional method of polishing both side surfaces of the wedge shape. It is easy to reduce the amount of deviation between the center of the polishing tip and the center of the optical fiber core. Accordingly, it is not necessary to check the polishing accuracy by repeatedly attaching and removing.

  The structure of the optical fiber tip processing apparatus of the present invention will be specifically described with reference to FIG. FIG. 3 is a central cross-sectional view showing the processing apparatus in a state in which the fixing jig 9 on which the optical fiber 1 is set is mounted.

  The optical fiber tip processing apparatus mainly comprises an optical fiber rotating plate 12 for rotating the fixing jig 9, a driving unit 17 for applying rotational driving to the optical fiber rotating plate 12, and a drive transmitting unit 18. The optical fiber rotating plate 12 is connected to the optical fiber rotating plate 12 through a drive transmission unit 18 connected to the rotating shaft 17, and in conjunction with the driving unit 17, the optical fiber rotating plate 12 rotates about the rotating plate central axis 16. . The optical fiber rotating plate 12 is fixed by a rotating plate support plate 20 and a rotating plate holding part 19.

  A fixing jig insertion hole (not shown) is formed at a predetermined distance away from the center of the optical fiber rotating plate 12, and the fixing jig 9 is perpendicular to the fixing jig insertion hole (not shown) of the optical fiber rotating plate 12. Since it is inserted and fixed, the fixing jig 9 rotates and revolves as the optical fiber rotating plate 12 rotates. At the same time, the tip of the optical fiber 1 abuts on the optical fiber polishing plate 2 and moves on the polishing surface 21 to draw a locus of a circular orbit. By repeating the revolution, the tip of the optical fiber 1 is polished into a conical shape.

  At this time, the optical fiber 1 is rotated together with the fixing jig 9 by bending the distal end portion of the optical fiber 1 while holding the fulcrum 92 on the side opposite to the traveling direction (rotation direction) of the support portion 94. At this time, since the optical fiber is sandwiched and fixed in the first through hole 93a of the fiber fixing portion 93, the optical fiber itself does not rotate even with this rotation.

  When rotating in this way, the tip of the optical fiber 1 is polished by the polishing surface 21. The angle θ of the conical taper portion 22 at the tip of the optical fiber 1 is such that the gap portion 95 of the support portion 94 has an elliptical shape, so that the core axis center of the optical fiber 1 fixed to the fixing portion 93 or the outside The distance from the diameter center axis 3 to the fulcrum 92 periodically changes during one rotation, and the outer periphery of the optical fiber tip does not uniformly contact the polishing surface, and the polishing angle and the polishing amount correspond to an elliptical cycle. Become. As a result, the end portion of the polished optical fiber has an elliptical end surface as shown in FIG.

  Since the optical fiber 1 attached to the fixing jig 9 is always in contact with and pressed against the fulcrum 92 during the polishing process, the optical fiber 1 may be damaged by the fulcrum 92. Therefore, the support portion 94 is chamfered. It is preferable to provide an R shape so that the optical fiber is not edged as much as possible.

  Examples of the present invention will be described.

  Using the processing apparatus shown in FIG. 3, the elliptical processing of the tip portion of the optical fiber 1 was performed.

  The optical fiber 1 was a single mode fiber having an outer diameter of 125 ± 1 μm and a coating diameter of 250 μm. The length of the optical fiber 1 at this time was 100 cm.

  As the fixing jig 9, a stainless steel cylindrical holder having an outer diameter of 16 mm and a length of 70 mm was used. The coating removal treatment was performed in advance so that the coating removal portion at the tip of the optical fiber 1 was 12 mm.

  The distance from the bottom surface 96 of the fixing jig 9 to the polishing surface 21 of the polishing plate 2 was 3 mm. The oval shape of the gap portion 95 of the holder instruction portion 94 is an oval shape having a major axis of 8 mm and a minor axis of 3 mm.

  The rotation speed of the optical fiber rotating plate 3 of the processing apparatus was set to 60 rpm. The polishing sheet pasted on the polishing plate 2 was prepared using a diamond # 4000 film with a polishing time of about 120 seconds. As a result, the cross-sectional shape of the end face of the optical fiber had an aspect ratio of 2: 1 between the major axis and the minor axis. The processing of the tip of the elliptical optical fiber could be realized. The tip portion of the optical fiber having an elliptical tip shape thus obtained was heated and melted to have a shape with a curvature at the tip portion. The curvature radius of the tip was 14 microns in the major axis direction and 6 microns in the minor axis direction. When the wedge fiber thus obtained was coupled to an optical semiconductor laser for light amplification having an emission wavelength of 980 nm, a good coupling efficiency of 70% was obtained.

The structure of the holder used for the processing apparatus by this invention is shown, (a) is the side view, (b) It is the bottom view of the figure (a), (c) is that the optical fiber is grind | polished It is sectional drawing which shows the state of time. (A) (b) shows the shape of the front-end | tip part of the optical fiber produced using the processing apparatus by this invention. It is a center cross-sectional view which shows the state in which the holder was installed in the processing apparatus which implements the principle of the processing method by this invention. (A), (b) is a figure for demonstrating the conventional tip processing method of a wedge fiber. It is a figure for demonstrating the shape of the conventional wedge fiber, (a) is a front view, (b) is the side view. It is a figure for demonstrating the shape of the conventional wedge fiber. It is a figure for demonstrating the shape of the conventional wedge fiber.

Explanation of symbols

1: Optical fiber 2: Polishing plate 21: Polishing surface 22: Conical taper part 3: Center axis 9: Fixing jig 91: First through hole 92: Second through hole 93: Optical fiber fixing part 94: Optical fiber support Portion 95: Gap portion 96: Bottom surface 10, 20, 30: Wedge fiber 11: Lens 11a: Inclined surface 12: Optical fiber rotating plate 14: Fixing jig insertion hole 16: Rotating plate central axis 17: Drive unit 18: Drive transmission unit 19: Rotating plate holder 20: Rotating plate support plate 22: Semi-cylindrical curved surface 32: Plane portion 98: Fixing jig θ: Angle

Claims (1)

A fixing having a first through hole for holding and holding an optical fiber and a second through hole in which the tip of the optical fiber protrudes from one opening which is larger than the first through hole and has an elliptical shape. A jig and a polishing disc for polishing the tip of the optical fiber, and sliding the surface of the polishing disc in a state where the tip of the optical fiber is bent at an acute angle with respect to the surface of the polishing disc An optical fiber tip processing apparatus characterized by being rotated.

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