JP5628763B2 - Method and apparatus for fusion splicing of optical fiber by CO laser - Google Patents

Description

  The present invention relates to an optical fiber fusion splicing method and apparatus using a CO laser.

FIG. 1 is a view for explaining optical fiber fusion splicing by CO ₂ laser irradiation according to the prior art shown in Non-Patent Document 1. FIG. 1 shows optical fibers 1 and 2, a CO ₂ laser oscillation device 3, V grooves 4 and 5, concave mirrors 6 and 7, and a backscattered light detection device 8.

The optical fibers 1 and 2 are fused by laser irradiation. The CO ₂ laser oscillation device 3 is connected to a laser power source and a modulation controller (not shown), and outputs a CO ₂ laser for fusing the optical fibers 1 and 2. V-grooves 4 and 5 accommodate optical fibers 1 and 2, respectively. The V-groove 5 is provided on an x-y-z axis adjustment manipulator (not shown), and by adjusting the position of the V-groove 5 by adjusting the axis adjustment manipulator, the optical fibers 1 and 2 can be adjusted. Position adjustment with respect to the xyz axis can be performed. The concave mirror 6 reflects the CO ₂ laser output from the CO ₂ laser oscillator 3 toward the concave mirror 7, and the concave mirror 7 reflects the CO ₂ laser reflected by the concave mirror 6. The shapes of the concave mirrors 6 and 7 can be, for example, elliptical. The backscattered light detection device 8 is connected to the optical fiber 1 and monitors backscattered light composed of 1.3 μm laser light supplied from the optical fiber 1.

A conventional method used for single mode fusion splicing with a CO ₂ laser will be described with reference to FIG. CO ₂ laser output from CO ₂ laser oscillator 3 is reflected by the concave mirror 6, a position where the optical fibers 1 and 2 are slightly away from the fusing surface 9 of fusing (beam focusing in Figure 1 After being condensed at the position 10), the fusion interface 9 of the optical fibers 1 and 2 is irradiated from the concave mirror 6 side installed above the optical fibers 1 and 2 at the defocus position. A part of the CO ₂ laser light reflected by the concave mirror 6 does not contribute to the fusion of the optical fibers, but is enlarged by the concave mirror 7 installed below the optical fibers 1 and 2 by expanding the beam diameter. Reflected on the concave mirror 6 side. The CO ₂ laser light reflected by the concave mirror 7 is condensed at a position slightly below the fusion interface 9 (beam condensing position 15 in FIG. 1), defocused again, and fused. The lower side of the interface 9 is irradiated. Thus, the optical fibers 1 and 2 are fused by irradiating the optical fibers 1 and 2 with CO ₂ laser light from the upper side and the lower side.

  Before such laser irradiation, the backscattered light detection device 8 is used to monitor the backscattered light of the 1.3 μm laser light in the optical fiber 1 to adjust the position of the V-groove 5. And 2 are adjusted relative to each other. After the relative positional adjustment of the optical fibers 1 and 2 is performed and the optimum positional relationship is maintained, the above-described laser fusion is performed.

According to the conventional method shown in FIG. 1, the focal points of the concave mirrors 6 and 7 are shifted slightly upward and downward from the fusion interface 9 to defocus the CO ₂ laser beam. Heating is performed uniformly from above and below. On the other hand, the oscillation wavelength 10.6μm of CO ₂ laser has a high absorption rate of a quartz material which is the main constituent material of the optical fiber, if no defocus of CO ₂ laser light, 1 and primarily CO ₂ laser beam optical fiber Absorption occurs on the surface irradiated to 2 and heating cannot be performed uniformly. However, by adopting the conventional method shown in FIG. 1, the upper and lower side surfaces of the fusion interface 9 are also irradiated with CO ₂ laser light, and the fusion bonding of the optical fibers without laser processing traces at the fusion interface 9 is performed. A surface is obtained. Therefore, when a stress load is generated in the optical fiber fused portion, the stress concentration on the joint surface can be reduced, and a high-strength fused optical fiber is realized.

  An application area required for the laser fusion technique will be described with reference to FIG. FIG. 2 is a conceptual diagram of on-board optical fiber fusion splicing for mounting a plurality of optical modules having an optical fiber optical interface on a circuit board. In FIG. 2, an optical module 20 to which a plurality of optical fibers 21 are connected, a circuit board 22 for installing the optical modules 20, an optical connector 23 connected to the optical fibers 21, and a fusion splicing point. 24. As shown in FIG. 2, a plurality of optical modules 20 are installed on a circuit board 22, and optical fibers 21 of the plurality of optical modules 20 are fusion-bonded at fusion-bonding points 24 on the circuit board 22. Yes.

  As the communication traffic increases in recent years, the optical modules 20 for high-speed signal processing mounted on the circuit board 22 are increasingly increasing. As a result, a low-loss optical connection is required between the optical modules 20. As shown in FIG. 2, as the number of optical modules 20 mounted on the circuit board 22 increases, a large number of fusion splicing points 24 are required. When providing a plurality of fusion splice points 24 on the circuit board 22 as described above, the fusion splicing technique using two concave mirrors according to the prior art as shown in FIG. However, although a concave mirror is required, a sufficient space cannot be secured for installing the concave mirror on the upper and lower surfaces of the circuit board 22. Therefore, when the on-board optical fiber fusion splicing as shown in FIG. 2 is performed, it is difficult to fuse the optical modules 20 with the optical system configuration specification according to the prior art shown in FIG.

  An example of the prior art different from the prior art shown in FIG. 1 regarding optical fiber fusion will be described with reference to FIG. FIG. 3 shows an overview of the arc discharge fusion technique used when laying optical fiber cables. In the arc discharge fusion splicing device 30 shown in FIG. 3, an electrode 33 for arc discharge fusion splicing of the optical fibers 1 and 2 is provided.

  When the arc discharge fusion splicing device 30 shown in FIG. 3 is applied to the on-board optical fiber fusion splicing shown in FIG. 2, the extra lengths 31 and 32 are respectively added to the optical fibers 1 and 2, as shown in FIG. The optical fibers 1 and 2 are drawn out from the circuit board 22 shown in FIG. 2, and the optical fibers 1 and 2 are accommodated in the arc discharge fusion splicing device 30. After accommodating the optical fibers 1 and 2, arc fusion is performed between the electrodes 33 in the arc discharge fusion splicing device 30, thereby completing the fusion splicing of the optical fibers 1 and 2.

  However, when the arc discharge fusion splicing device 30 shown in FIG. 3 is applied to the on-board optical fiber fusion splicing shown in FIG. 2, the extra lengths 31 and 32 of the optical fibers 1 and 2 are shown in FIG. Since it becomes necessary to accommodate the circuit board 22 or the apparatus on which the circuit board 22 is mounted, the circuit board 22 or the apparatus for mounting the circuit board 22 is disadvantageous in terms of compactness.

FIG. 4 shows an ideal laser fusion mode in consideration of circuit board mounting of a large number of optical modules as shown in FIG. FIG. 4 shows the optical fibers 1 and 2, the CO ₂ laser oscillation device 3, the circuit board 22, the fusion splicing point 24, and the optical fiber alignment housing member 41. Using the CO ₂ laser oscillation device 3, the CO ₂ laser is irradiated to the optical fibers 1 and 2 accommodated and fixed in the optical fiber alignment accommodating member 41.

As shown in FIG. 4, the extra length of the optical fibers 1 and 2 is made as short as possible so that the optical fiber fusion splicing point 24 is accommodated in the circuit board 22. In this state, it is desirable to perform fusion by irradiating the optical fibers 1 and 2 with the CO ₂ laser from the CO ₂ laser oscillation device 3 provided above the circuit board 22. Therefore, we have made the basic structure shown in FIG. 4 using a CO ₂ laser having a high absorption rate with respect to quartz, which is the main constituent material of the optical fiber, while devising the optical fiber housing member and the laser irradiation method. I tried to fuse.

A method for fusing an optical fiber by a CO ₂ laser without using a condensing optical system from the upper and lower surfaces of the optical fiber by a concave mirror according to the prior art as shown in FIG. 1 will be described with reference to FIG. In FIG. 5, a stage 51, a V-groove substrate 52 installed on the stage 51 and having V-grooves 4 and 5 for accommodating the optical fibers 1 and 2, and the optical fibers 1 and 2, the V-groove 4 and 5 with respect to the pressing plate 53-a and 53-b for pressing and positioning to 5, the pressing plate holding arms 54-a and 54-b for holding the pressing plates 53-a and 53-b, and the stage 51, respectively. A laser fusion jig 50 including a hinge mechanism rotating shaft 55 for opening and closing the holding plate holding arms 54-a and 54-b, a magnetic force adjusting screw 56 built in the holding plate holding arm 54, and a CO ₂ laser. An oscillating device 3 is shown. Here, the x-axis direction in FIG. 5 and FIG. 8 described below indicates the optical fiber array direction, the y-axis direction indicates the longitudinal direction of the optical fiber, and the z-axis direction indicates the height direction. Further, in FIG. 5 and FIG. 8 described below, for simplification, only one pair of the optical fibers 1 and 2 is shown in the V grooves 4 and 5, but a plurality of V grooves 4 and 5 are shown. Can be formed on the V-groove substrate 52 and a plurality of pairs of optical fibers 1 and 2 can be arranged in the V-grooves 4 and 5.

  The optical fiber 1 is aligned and accommodated in the V-groove 4 of the V-groove substrate 52, and the optical fiber 2 is aligned and accommodated in the V-groove 5 of the V-groove substrate 52 arranged opposite to the optical fiber 1 accommodation. The The holding plate 53-a is used to hold the optical fiber 1 against the V-groove 4 and accommodate it in a certain clearance when the holding plate holding arm 54-a is closed, and the holding plate 53-b is a holding plate. When the holding arm 54-b is closed, the optical fiber 2 is pressed against the V-groove 5 to be accommodated within a certain clearance. The holding plate holding arms 54-a and 54-b are configured to be rotatable around a hinge mechanism rotating shaft 55 built in the stage 51, and the holding plate holding arms 54-a and 54 are rotated by the hinge mechanism rotating shaft 55. -B can be opened and closed. The magnetic force adjusting screws 56 are built in the holding plate holding arms 54-a and 54-b, respectively, and are installed so as to generate a magnetic force with a magnet (not shown) embedded in the stage 51. By adjusting the pushing amount of the magnetic force adjusting screw 56, the magnetic force generated between the presser plate holding arms 54-a and 54-b and the magnet embedded in the stage 51 can be adjusted. . As shown in FIG. 5, the optical fibers 1 and 2 are accommodated in the V grooves 4 and 5, respectively, and the holding plates 54-a and 54-b are closed by the hinge mechanism rotating shaft 55, thereby the optical fibers 1 and 2. Are positioned with respect to the x-axis direction and the z-axis direction.

  Further, the holding plates 53-a and 53-b are configured to come into contact with the guide pins 57 accommodated in the V grooves 4 and 5 when the holding plate holding arms 54-a and 54-b are closed. The diameter of the guide pin 57 is set slightly larger in the submicron order than the diameter of the optical fibers 1 and 2. By adopting this configuration, when the pressing plate holding arms 54-a and 54-b are closed, the pressing plates 53-a and 53-b and the optical fibers 1 and 2 accommodated in the V grooves 4 and 5, respectively. Therefore, the optical fibers 1 and 2 accommodated in the V grooves 4 and 5 facing each other can be positioned with submicron accuracy.

FIG. 5A shows the yz cross section of the portion where the optical fibers 1 and 2 are accommodated in the laser welding jig 50 and the optical fiber 1 from the CO ₂ laser oscillation device 3 provided above (+ z axis direction). 2 and 2 show a state in which the CO ₂ laser 58 is irradiated to the fusion interface 9 between the _two . As shown in FIG. 5A, the optical fibers 1 and 2 are disposed in the V-grooves 4 and 5, respectively, and the pressing plate holding arms 54-a and 54-b are closed to hold the pressing plates 53-a and 53. The optical fibers 1 and 2 are pressed against the V-grooves 4 and 5 by -b, and the optical fibers 1 and 2 are aligned in the x-axis direction and the z-axis direction. Thereafter, by buckling one optical fiber 1 toward the optical fiber 2 side, the optical fiber 1 can be buckled. The quartz of the optical fibers 1 and 2 is fused at the fusion interface 9 where the optical fibers 1 and 2 are fused by irradiating the CO ₂ laser 58 from the CO ₂ laser oscillation device 3 with the optical fiber 1 buckled. When the material evaporates and melts, the quartz material of the optical fibers 1 and 2 is supplied toward the fusion interface 9 by the pressing force, and the fusion is completed.

As shown in FIG. 5A, when heating is performed uniformly over the entire fusion interface 9 of the optical fibers 1 and 2 by laser irradiation from only one direction by the CO ₂ laser oscillation device 3 provided above. The CO ₂ laser 58 is defocused so that the beam diameter is widened at the laser irradiation position of the optical fiber by providing the beam waist position 59, which is the condensing position of the CO ₂ laser light 58, above the fusion interface 9. The FIG. 5B shows an enlarged view of the laser irradiation position. As shown in FIG. 5 (b), fusion has been attempted so that the CO ₂ laser beam 58 penetrates as much as possible to the side and bottom surfaces of the optical fiber so that the CO ₂ laser 58 is defocused at the laser irradiation position. . In particular, as shown in Non-Patent Document 2, CO ₂ laser light having a laser wavelength of 10.6 μm has an extremely high absorption rate to the quartz material, which is the main constituent material of the optical fiber, and is absorbed on the surface of the optical fiber. Becomes dominant. Therefore, in order for heat to be uniformly distributed at the fusion interface 9 between the optical fibers 1 and 2, the CO ₂ laser 58 is directly defocused and directly irradiated onto the optical fiber, so that the CO ₂ laser 58 can be directly applied to the optical fiber 1. It is desirable to irradiate the two fusion interfaces 9 as uniformly as possible.

FIG. 6 is a graph showing the dependency between the height from the bottom surface 57 of the stage 51 and the CO ₂ laser beam diameter when the laser welding jig 50 shown in FIG. 5 is irradiated with the CO ₂ laser light 58. In FIG. 6, an acrylic plate was installed at each height position from the bottom of the stage, and the processing area diameter of the acrylic plate processed by irradiating the acrylic plate with a CO ₂ laser was measured. In FIG. 6, the horizontal axis indicates the height position [cm] from the bottom of the stage, and the vertical axis indicates the processing area diameter [mm] of the acrylic plate by CO ₂ laser light. With respect to the horizontal axis of the graph shown in FIG. 6, the position of the height origin is set on the bottom surface 60 of the stage 51 in FIG. 5.

As shown in FIG. 6, the optical fiber accommodation height position, which is the height from the bottom surface 60 of the stage 51 to the fusion interface 9 of the optical fibers 1 and 2, is a height position of about 10 mm from the bottom surface 60 of the stage 51. The beam waist position 59, which is the condensing position of the CO ₂ laser 58, was set at a position about 30 mm away from the optical fiber accommodation height position in the + z-axis direction. As shown in FIG. 6, the processing region diameter at the optical fiber accommodation height position was 2.5 mm. On the other hand, the gap between the V-groove substrates 52 at the laser irradiation position of the laser welding jig 50 shown in FIG. 5 is typically set to 1 mm, and the processing region diameter at the optical fiber accommodation height position is 2. Since it is smaller than 5 mm, the CO ₂ laser beam 58 is applied not only to the optical fibers 1 and 2 but also to the V-groove substrate 52 of the laser fusion jig 50.

The influence of CO ₂ laser irradiation on the laser fusion jig 50 when optical fiber fusion is realized using the laser fusion jig 50 shown in FIG. 5 will be described with reference to FIG. FIGS. 7A, 7B, and 7C are enlarged views of a damaged portion showing examples of damage that has occurred in the V-groove substrate shown in FIG. The arrows in FIGS. 7A, 7B, and 7C indicate the damaged site. As shown in FIGS. 7A, 7B, and 7C, some cracks indicating breakage appear in the portion of the V-groove substrate 52 around the fusion splicing point where the laser is irradiated to the optical fiber. Therefore, it was found that the laser irradiation resistance of the V-groove substrate 52 is lost by irradiating the V-groove substrate 52 using quartz with laser. Further, as shown in Non-Patent Document 3, when zirconia ceramics having excellent heat resistance and machining characteristics are used for the V-groove substrate, a small amount of zirconia ceramics is mixed in the fusion interface of the optical fiber. It became clear. It is thought that the optical fiber core deformation is brought about by this inclusion, and it is considered that the fusion splice loss is also affected. Therefore, a quartz material should be used instead of zirconia ceramics as a material constituting the V-groove substrate. Is desired.

L. Rivoallan, J. Y. Guilloux, and P. Lamouler, “Monomode Fiber Fusion Splicing with CO2 laser,” IEE Electronics Letters, vol.19, no.2, pp.54-55. Naoyuki Kitamura, Kohei Fukumi, Junji Nishii “External Field Manipulation Technology” NEW GLASS −Special Achievements and Prospects of Nano Glass Project−Vol.21 No.2 pp.25-30, 2006 S. Koike et al., “SPring-8 X-ray Micro-Tomography Observations of Zirconium Inclusions in CO2 laser Fusion Splice for Single Mode Optical Fibers,” IEEE Transactions on components, Packaging, and Manufacturing Technology, vol.1 no.1 pp.100-110, (2011).

  In the fusion splicing of on-board optical fibers as shown in FIG. 2, by reducing the extra length of the optical fiber on the circuit board and reducing the deterioration of the V-groove substrate, good mechanical strength with low connection loss distribution The problem is to obtain a fused optical fiber having quality.

In order to solve the above-described problem, a method according to claim 1 of the present invention includes a plurality of V-grooves for aligning and accommodating guide pins, the first optical fiber, and the second optical fiber , A V-groove substrate made of a quartz material having a gap provided at a position where the first optical fiber and the second optical fiber abut each other ; a stage holding the V-groove substrate; and the first A pressing plate for pressing the optical fiber and the second optical fiber into the V groove, a pressing plate holding arm for holding the pressing plate, and opening and closing the pressing plate holding arm with respect to the stage. An optical fiber using an optical fiber fusion splicing device comprising a rotation shaft for a hinge mechanism and a laser oscillation unit for irradiating a laser to a portion where the first optical fiber and the second optical fiber are abutted with each other In the fusion splicing method, the holding plate holding arm is closed by the hinge mechanism rotating shaft, and the first optical fiber and the second optical fiber accommodated in the V-groove are abutted and aligned. And a step of fusing the first optical fiber and the second optical fiber by irradiating a CO laser to the abutted portion by the laser oscillating unit, and condensing the CO laser. position, Ri Ah in the butted portion, the CO laser is characterized in that the beam spot diameter of the CO laser at the condensing position of the CO laser is configured to be smaller than the gap.

  According to a second aspect of the present invention, in the method according to the first aspect, the fusing step is performed by pushing the first optical fiber toward the second optical fiber. It is performed in a state where buckling occurs in one optical fiber.

An optical fiber fusion splicing device according to claim 3 of the present invention includes a plurality of V-grooves for aligning and accommodating guide pins, the first optical fiber, and the second optical fiber, and the first optical fiber. A V-groove substrate having a gap provided at a position where it abuts against the second optical fiber; a stage for holding the V-groove substrate; and pressing the first optical fiber and the second optical fiber. A holding plate for receiving the holding plate, a holding plate holding arm for holding the holding plate, a hinge mechanism rotating shaft for opening and closing the holding plate holding arm with respect to the stage, and the first light; A laser oscillating unit that irradiates a portion of the fiber and the second optical fiber that irradiates the laser, and closing the holding plate holding arm by the hinge mechanism rotation shaft, In contact with volume are said guide pin and the pressing plate, said accommodated in the V-groove first optical fiber has a constant clearance between the bottom surface and the first optical fiber upper surface of the pressing plate held manner, the second optical fiber's rating before accommodated in the V-groove is held to have a predetermined clearance between the bottom surface and the second optical fiber the upper surface of the pressing plate, the first By projecting the optical fiber of the first optical fiber toward the second optical fiber side, laser irradiation is performed on the abutted portion by the laser oscillation unit in a state where buckling occurs in the first optical fiber, an optical fiber fusion splicing apparatus for fusing the optical fiber, the laser oscillating unit oscillates the CO laser, focusing position of the CO laser, Ri Ah in the butted portion, the O laser is characterized in that the beam spot diameter of the CO laser at the condensing position of the CO laser is configured to be smaller than the gap.

  Optical fiber fusion splicing can be realized by laser irradiation from one direction with respect to the optical fiber wired on the circuit board. Further, without defocusing the laser light in laser irradiation from one direction, V While suppressing deterioration of the groove substrate, it is possible to heat the optical fiber uniformly at the fusion interface, and it is possible to realize a fusion optical fiber having stable mechanical strength.

Is a diagram illustrating an optical fiber fusion splicing optical system according to the CO ₂ laser radiation according to the prior art. It is a figure for demonstrating the subject of an on-board optical fiber fusion splicing. It is a figure for demonstrating the on-board optical fiber fusion splicing by the arc discharge fusion splicing apparatus which concerns on a prior art. It is a figure which shows the form calculated | required at the time of laser fusion splicing application to on-board optical fiber fusion splicing. Is a diagram showing an optical experimental system of the optical fiber fusion splicer according to the CO ₂ laser radiation. CO is a diagram showing the dependence between the height position of the beam diameter and the stage bottom in ₂ laser defocus optical system. In the optical fiber fusion splicer according to the CO ₂ laser defocus the optical system is a diagram showing an example of a failure occurring in the laser welding jig. It is a figure which shows the optical experiment system of the optical fiber fusion splicing by CO laser irradiation concerning this invention.

  A method for fusion splicing of optical fibers by CO laser irradiation according to an embodiment of the present invention will be described with reference to FIG. FIG. 8 shows an optical experimental system of CO laser irradiation for optical fiber fusion splicing. 8, the stage 51, the V-groove substrate 52, the pressing plates 53-a and 53-b, the pressing plate holding arms 54-a and 54-b, the hinge mechanism rotating shaft 55, and the magnetic force adjusting screw 56 are shown. A laser welding jig 80 provided with a guide pin 57 and a CO laser oscillation device 81 for oscillating a CO laser 82 are shown. The optical experimental system shown in FIG. 8 is the same as the optical experimental system of FIG. 5 described as an example of the prior art, and the description of the experimental procedure using the laser welding jig is omitted.

FIG. 8A shows a yz cross section of a portion where the optical fibers 1 and 2 are accommodated in the laser fusion jig 80, and the optical fiber 1 and the optical fiber 1 from the CO laser oscillation device 81 provided above (+ z axis direction). 2 shows a state in which the CO laser 82 is irradiated to the two fusion interfaces 9. As shown in FIG. 8A, in the optical fiber fusion splicing according to the embodiment of the present invention, laser fusion of an optical fiber is performed using a CO laser oscillated by a CO laser oscillation device 81. CO lasers for wavelengths shorter than the CO ₂ laser, when using a CO laser can be reduced beam spot diameter than using CO ₂ lasers.

In addition, when laser irradiation is performed on an optical fiber made of a quartz material using a CO ₂ laser as in the prior art, since the absorption coefficient of the CO ₂ laser with respect to the quartz material is 371 cm ⁻¹ , For an optical fiber having a diameter of 125 μm, thermal energy from irradiation penetrates from the surface of the optical fiber to a depth of about 50 μm and is consumed. Therefore, the conventional CO ₂ laser irradiation, the quartz material is dominant be transpired from the optical fiber surface, it is necessary to increase defocus the CO ₂ laser, the beam spot diameter by the CO ₂ laser progresses As a result, the CO ₂ laser is irradiated onto the V-groove substrate, and the V-groove substrate is deteriorated. On the other hand, when a laser beam is irradiated to an optical fiber composed of a quartz material using a CO laser, the CO laser has an absorption coefficient of 129 cm ⁻¹ for the quartz material. Even when the optical fiber 82 is irradiated to the optical fiber, the heat energy by irradiation penetrates from the optical fiber surface to a depth of about 100 μm and is consumed with respect to the outer diameter of the optical fiber of 125 μm. Therefore, when the optical fiber is irradiated with the CO laser, the fusion interface corresponding to a large part of the outer diameter of the optical fiber of 125 μm is obtained even when the optical fiber is focused on the abutting portion without defocusing the CO laser. The thermal energy absorbed by the CO laser is propagated to 9 and can be heated uniformly over the entire fusion interface 9.

  Therefore, as shown in the enlarged view of the laser irradiation position in FIG. 8B, it is not necessary to defocus the CO laser, and the beam waist position 83 which is the condensing position of the CO laser is abutted between the optical fibers. Therefore, the beam spot diameter of the CO laser at the fusion splicing point of the optical fiber should be sufficiently smaller than the gap (typically 1 mm) between the V-groove substrates 52 at the laser irradiation position. Can do. Therefore, it is possible to reduce the amount of CO laser irradiation to the V-groove substrate 52 around the beam waist position 83 at the time of laser fusion, and it is possible to suppress deterioration damage to the V-groove substrate 52. As a result, it is possible to stably hold the optical fibers 4 and 5 stably at the time of laser fusion, and to prevent the V-groove substrate material from melting into the fusion interface 9. The strength can be stabilized. Moreover, since the initial design dimensional accuracy of the V-groove substrate can be maintained, it is possible to obtain a low connection loss distribution of the fused optical fiber.

As described above in detail with the embodiments, the fiber fusion by the CO laser irradiation according to the present invention has the same wavelength as that of the optical fiber fusion by the CO ₂ laser irradiation which has been realized by the conventional technology. Since the surface absorption rate of the laser is lower than that of the quartz material, the penetration length of the thermal energy into the quartz material can be extended. Therefore, the beam spot diameter of the CO laser irradiated to the fusion splicing point of the optical fiber can be reduced. As a result, for example, the laser beam is applied to a portion other than the optical fiber made of quartz material, such as a V-groove substrate. Irradiation can be reduced, and damage to the components of the laser welding jig can be reduced. Further, as described above, the penetration length of thermal energy due to absorption of CO laser light is about 100 μm and the outer diameter of a typical optical fiber is 125 μm. Therefore, light having the same outer diameter without defocusing the laser light. It becomes possible to uniformly heat the entire fusion interface of the fiber. As a result, stable fusion splicing and mechanical strength can be expected, and a high-quality fused optical fiber can be realized.

1, _2, 21 Optical fiber 3 CO ₂ laser oscillation device 4, 5 V groove 6, 7 Concave mirror 8 Back scattered light detection device 9 Fusion interface 20 Optical module 22 Circuit board 23 Optical connector 24 Fusion connection point 30 Arc discharge Fusion splicer 31, 32 Extra length 33 Electrode 41 Optical fiber alignment housing member 50, 80 Laser fusion jig 51 Stage 52 V-groove substrate 53-a, 53-b Holding plate 54-a, 54-b Holding plate holding Arm 55 Hinge mechanism rotating shaft 56 Magnetic force adjusting screw 57 Guide pin 58 CO ₂ laser 59, 83 Beam waist position 60 Stage bottom surface 81 CO laser oscillation device 82 CO laser

Claims (3)

A plurality of V grooves for aligning and accommodating the guide pin, the first optical fiber, and the second optical fiber, and a gap provided at a position where the first optical fiber and the second optical fiber are abutted with each other with the door, and the V-groove substrate composed of quartz material,
A stage for holding the V-groove substrate;
A pressing plate for pressing and holding the first optical fiber and the second optical fiber in the V-groove;
A holding plate holding arm for holding the holding plate;
A hinge mechanism rotating shaft for opening and closing the pressing plate holding arm with respect to the stage;
A method of fusion-splicing an optical fiber using an optical fiber fusion splicing device comprising: a laser oscillation unit that irradiates a laser to a portion where the first optical fiber and the second optical fiber are abutted;
Closing the holding plate holding arm with the hinge mechanism rotation shaft, and abutting and aligning the first optical fiber and the second optical fiber housed in the V-groove;
Fusing the first optical fiber and the second optical fiber by irradiating a CO laser to the butted portion by the laser oscillation unit,
Condensing position of the CO laser, Ri Ah in the butted portion,
The CO laser is configured such that a beam spot diameter of the CO laser at a condensing position of the CO laser is smaller than the gap .   The step of fusing is performed in a state where buckling has occurred in the first optical fiber by advancing the first optical fiber toward the second optical fiber. The method of claim 1. A plurality of V grooves for aligning and accommodating the guide pin, the first optical fiber, and the second optical fiber, and a gap provided at a position where the first optical fiber and the second optical fiber are abutted with each other with the door, and the V-groove substrate composed of quartz material,
A stage for holding the V-groove substrate;
A pressing plate for pressing and holding the first optical fiber and the second optical fiber in the V-groove;
A holding plate holding arm for holding the holding plate;
A hinge mechanism rotating shaft for opening and closing the pressing plate holding arm with respect to the stage;
A laser oscillation unit for irradiating a laser to a portion where the first optical fiber and the second optical fiber are abutted with each other, and by closing the holding plate holding arm by the hinge mechanism rotating shaft, The received guide pin and the pressing plate are in contact with each other, and the first optical fiber received in the V-groove has a certain clearance between the bottom surface of the pressing plate and the upper surface of the first optical fiber. held manner, the second optical fiber's rating before accommodated in the V-groove is held to have a predetermined clearance between the bottom surface and the second optical fiber the upper surface of the pressing plate, the first By pushing the optical fiber toward the second optical fiber side, the laser oscillating unit causes the laser optical unit to squeeze the first optical fiber in a buckled state. An optical fiber fusion splicing device that fuses the optical fiber by irradiating the laser beam;
The laser oscillation unit oscillates a CO laser,
Condensing position of the CO laser, Ri Ah in the butted portion,
The optical fiber fusion splicing apparatus , wherein the CO laser is configured such that a beam spot diameter of the CO laser at a condensing position of the CO laser is smaller than the gap .