JP2011248048A - Optical fiber pig tail and optical module using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber pig tail and an optical element module which prevents optical fiber from breaking in optical fiber holding member and ensures long life reliability.SOLUTION: An optical fiber holding member 8 has a first through hole 2 formed at one side; a second through hole 6 having a larger diameter than that of the first through hole 2, which communicates with the first through hole 2; and an optical fiber introduction port 3 formed between the first through hole 2 and the second through hole 6 so as to communicate with each other and the diameter of which expands from the first through hole 2 toward the second through hole 6. The optical fiber introduction port 3 includes therein an alignment pad 12 including a third through hole having the inner diameter same as that of the first through hole; thereby adhesive clog is reduced and an optical fiber 11 is prevented from breaking due to swelling of the adhesive.

Description

  The present invention is an optical module that is incorporated in an optical module used in an optical communication transceiver, and that introduces or derives light from a light emitting element such as an LD (laser diode) or a light receiving element such as a PD (photodiode). The present invention relates to an optical fiber pigtail used for a portion holding a fiber.

  Optical modules for optical communication are becoming increasingly high-speed and broadband. In particular, in an optical module required for a long distance system, higher reliability is required. In such an optical module, for example, optical fiber pigtails as shown in Patent Document 1, Patent Document 2, and Patent Document 3 are used.

  FIG. 4 is a longitudinal sectional view showing such a conventional optical fiber pigtail 500. The optical fiber pigtail 500 includes an optical fiber holding member 58 composed of a capillary 51 and a pipe 55, and an optical fiber 61 composed of an optical fiber strand 59 and an optical fiber coating 60.

  The capillary 51 is made of a material such as glass or zirconia ceramics, and is a cylindrical body provided with a first through hole 52 for inserting and holding an optical fiber strand 59 in the center.

  The cylindrical pipe 55 is made of a metal such as a stainless alloy, and a second through hole 56 for inserting and holding the optical fiber coating 60 is provided at the center. Further, a counterbore 57 for press-fitting the capillary 51 is provided at one end.

  In the capillary 51, in order to introduce the optical fiber 59 into the first through hole 52, an optical fiber conductor formed so that its diameter increases from the first through hole 52 toward the second through hole 56 of the pipe 55 is formed. A strand entrance 53 is provided. The end side of the capillary 51 where the optical fiber strand inlet 53 is formed is press-fitted into a seating portion 57 of the pipe 55 (a hole provided in the length direction of the capillary 51 so as to insert the capillary 51). An optical fiber holding member 58 is formed.

  The optical fiber strand 59 from which the coating 60 of the optical fiber 61 is removed is inserted from the second through hole 56 side of the optical fiber holding member 58, and the tip is guided to the first through hole 52 through the optical fiber strand introduction port 53. Then, the first through hole 52 is inserted. Adhesive is injected into the second through hole 56 and the first through hole 52 at a position where the end of the optical fiber coating 60 substantially contacts the capillary 51 and cured at 100 ° C. or lower, so that the optical fiber 61 is held by the optical fiber holding member 58. Fixed to. The tip of the optical fiber strand 59 protruding from the end face of the capillary 51 is cut and then polished together with the capillary end face 54 to produce the optical fiber pigtail 500.

JP-A-8-220374 Japanese Patent Laid-Open No. 11-125739 JP 2007-17499 A

  However, in the conventional optical fiber pigtail 500 shown in FIG. 4, an adhesive pool is formed in the optical fiber introduction port 53, and is left in a high temperature and high humidity test (temperature 85 ° C.-humidity 85% atmosphere for 2,000 hours). ), The adhesive swells, stress is applied to the optical fiber 59, and the optical fiber 59 may break.

  An object of the present invention has been devised in view of the above-described problems, and is to provide an optical fiber pigtail and an optical element module in which the high-temperature and high-humidity reliability of an optical fiber is improved.

  In view of the above problems, an optical fiber pigtail according to an embodiment of the present invention includes a first through hole formed on one end side, and the first through hole formed on the other end side and connected to the first through hole. A second through hole having a larger diameter than the hole, and the first through hole and the second through hole are connected to each other, and the diameter is increased from the first through hole toward the second through hole. An optical fiber holding member having an expanded optical fiber strand inlet; an alignment pad disposed inside the optical fiber strand inlet and having a third through hole having the same inner diameter as the first through hole; An optical fiber that is inserted from the second through hole of the optical fiber holding member and holds the optical fiber in the first through hole and the third through hole is provided.

  In the above-mentioned optical fiber pigtail, the alignment pad preferably has a slit formed from the outer peripheral surface to the center portion instead of the third through hole.

  Further, the optical fiber holding member has a capillary having the first through hole and holding the optical fiber, and a pipe through which the capillary is inserted and held at one end side. It is preferable to consist of parts.

  In addition, it is preferable that an optical element is bonded to an end face having the opening of the first through hole on the one end side.

  The optical element is an optical isolator element, and a magnet is preferably bonded to an end face on the one end side around the optical isolator element.

  Furthermore, an optical module of the present invention includes any one of the above optical fiber pigtails and a cylindrical first holder into which one end side of the optical fiber holding member is inserted, and the optical fiber and the optical fiber are inserted on the one end side. And a case for storing the combined light emitting elements.

  According to the optical fiber pigtail according to an embodiment of the present invention, the optical fiber pigtail includes an alignment pad that is disposed inside the optical fiber strand introduction port and has a third through hole having the same inner diameter as the first through hole. The volume of the adhesive reservoir formed at the optical fiber strand inlet can be reduced. As a result, the stress applied to the optical fiber strand due to the swelling of the adhesive can be relaxed.

  In addition, if the alignment pad is provided with a slit formed from the outer peripheral surface to the central portion, the optical fiber can be guided to the central portion of the alignment pad along the outer peripheral surface and the slit of the alignment pad. Easy to insert strands.

(A) is a longitudinal sectional view showing an example of an embodiment of an optical fiber pigtail of the present invention, (b) is an enlarged perspective view showing an example of an embodiment of an alignment pad used for an optical fiber pigtail, and (c) is It is an expansion perspective view which shows the other example of embodiment of an alignment pad. It is a longitudinal cross-sectional view which shows the other example of embodiment of the optical fiber pigtail of this invention. It is a longitudinal cross-sectional view which shows an example of embodiment of the optical element module of this invention. It is a longitudinal cross-sectional view which shows the example of embodiment of the conventional optical fiber pigtail.

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

  FIG. 1 shows an example of an embodiment of an optical fiber pigtail 100 according to the present invention. FIG. 1 (a) is a longitudinal sectional view of the optical fiber pigtail 100, and FIG. 1 (b) is a diagram of FIG. FIG. 4C is an enlarged perspective view of the alignment pad 12 used in the optical fiber pigtail 100, and FIG.

  The optical fiber holding member 8 is made of ceramics, glass, metal, or the like, has one end face and the other end face facing the end face, and a through hole is formed from the one end face to the other end face. The through-hole has a first through-hole 2 formed on one end side, and a second through-hole 6 that is continuous with the first through-hole 2 and has a diameter larger than that of the first through-hole 2. Also, between the first through hole 2 formed at one end of the optical fiber holding member 8 and the second through hole 6 arranged on the extension line of the shaft of the first through hole 2 so as to communicate therewith. The optical fiber strand introduction port 3 having a diameter expanding from the first through hole 2 toward the second through hole 6 is formed so as to continuously connect the first through hole 2 and the second through hole 6 having different diameters. Has been.

  An alignment pad 12 is disposed inside the optical fiber strand inlet 3. The alignment pad 12 is made of the same material as the optical fiber holding member 8 and has a third through hole 13 through which the optical fiber 9 is inserted in the central axis direction, as shown in FIG. The third through hole 13 is arranged coaxially with the first through hole 2 and has the same inner diameter as the first through hole 2. The outer shape of the alignment pad 12 is preferably formed in a shape similar to the inner peripheral surface of the optical fiber strand introduction port 3. For example, the alignment pad 12 is formed in a conical shape that fits inside the optical fiber strand introduction port 3. Has been. The third through hole 13 is preferably arranged coaxially with the first through hole 2.

  Further, as shown in FIG. 1C, the alignment pad 12 is provided with a slit 14 formed from the outer peripheral surface to the central portion or from the inner wall surface of the third through hole 13 to the outer peripheral surface. preferable. The slit 14 has a width slightly wider than that of the optical fiber 9. This facilitates the passage of the optical fiber 9 through the slit 14. In other words, the optical fiber 9 is moved along the outer peripheral surface of the alignment pad 12, and when it reaches the position of the slit 14, the optical fiber 9 is passed through the slit 14. . When the slit 14 is not provided, a fine work is required to align the tip of the optical fiber strand 9 with the position of the opening of the third through hole 13 and then insert the optical fiber strand 9 into the third through hole 13. However, this can be easily performed by providing the slit 14.

  Then, the optical fiber 11 having the alignment pad 12 attached to the portion of the optical fiber 9 is inserted from the second through hole 6 side of the optical fiber holding member 8, and the tip of the optical fiber 9 protrudes from the first through hole 2. Thus, the optical fiber 11 is inserted into the optical fiber holding member 8. Since the tip of the optical fiber 9 is guided to the opening of the first through hole 2 by the optical fiber introduction port 3, the optical fiber 11 is inserted into the second through hole 6 and the first through hole 2. Not so difficult. In this way, the optical fiber strand 9 from which the coating 10 of the optical fiber 11 is removed is held inside the first through hole 2 and the third through hole 13, and the optical fiber coating 10 is in the second through hole 6. Held in. The alignment pad 12 is disposed in the optical fiber strand introduction port 3 and is disposed on the end face side of the optical fiber covering portion 10 of the 9 portions of the optical fiber strand.

  Thereafter, an adhesive is poured into the first through hole 2 from the gap between the opening of the second through hole 6 and the optical fiber 11. The adhesive is injected from the opening of the second through-hole 6 so as to be filled up to the first through-hole 2 by means such as suction from the first through-hole 2 side. Thereafter, the adhesive is cured at a high temperature of 100 ° C. or lower with a heater, a thermostatic bath, or the like. After curing, the excess optical fiber 9 protruding from the first through hole 2 is cut, and the end face 4 of the optical fiber holding member 8 is polished to a surface inclined at 4 ° to 8 ° with respect to the plane perpendicular to the optical axis. Thus, the optical fiber pigtail 100 is formed. The polishing angle of the end face 4 is provided to suppress near-end reflection of light. When polishing at 0 ° with respect to the plane perpendicular to the optical axis, the end face 4 may be coated with an antireflection film.

As described above, in the optical fiber pigtail 100 according to the embodiment of the present invention, the alignment pad 12 is disposed in the optical fiber strand introduction port 3, thereby forming about 0.13 mm formed in the optical fiber strand introduction port 3. About 85% of the adhesive pool of ³ could be reduced. As a result, the adhesive in the adhesive pool swells under a high temperature and high humidity test condition of a temperature of 85 ° C. and a humidity of 85%, and the stress applied to the optical fiber 9 is alleviated. Therefore, long-term reliability can be improved.

  FIG. 2 is a longitudinal sectional view of an optical fiber pigtail 200 according to another embodiment of the present invention. The optical fiber holding member 8 in the present embodiment is a combination of the capillary 1 and the pipe part 5, and the capillary 1 is inserted into a sitting part 7 formed on one end side of the pipe part 5. The overall shape of the optical fiber holding member 8 composed of the capillary 1 and the pipe portion 5 is the same as that of the optical fiber holding member 8 shown in FIG. Therefore, in FIG. 2, the same reference numerals are given to portions having the same function as the optical fiber holding member 8 of FIG.

  In the optical fiber pigtail 100 of the present embodiment, an example is shown in which the optical element 24 is further attached to the tip surface of the capillary 1 so as to cover the opening of the first through hole. The optical element 24 is, for example, an optical isolator 26, and FIG. 2 shows an embodiment of an optical fiber pigtail 200 with an optical isolator in which the optical isolator 26 is attached to the end face of the optical fiber holding member 8.

  The capillary 1 has a cylindrical shape with an outer diameter of 1.4 mm or the like, is made of ceramics or glass, and has a first through hole 2 in the central axis direction. The diameter of the 1st through-hole 2 is formed in the internal diameter of 0.1255-0.1265 mm slightly larger than the diameter 0.125mm of the optical fiber strand 9. FIG. An optical fiber introduction port 3 is provided on the side of the opening of the first through hole 2 that is inserted into the optical fiber holding member 8 of the capillary 1. The size of the opening of the optical fiber introduction port 3 is a cone shape having a diameter of about 1.0 mm and an angle between the axial direction of the first through hole 2 of about 45 ° and expanding toward the end face. Yes. As an angle between the first through hole 2 and the axial direction, about 30 ° is used in addition to about 45 °.

  The pipe part 5 consists of metals, such as a stainless alloy, and has the 2nd through-hole 6 in the center part axial direction. The diameter of the second through hole 6 is about 1.0 mm, which is slightly larger than the diameter 0.9 mm of the optical fiber coating 10. A counterbore 7 for press-fitting the capillary 1 is provided at one end of the pipe portion 5 coaxially with the second through hole 6. The counterbore part 7 is formed in a cylindrical shape having an inner diameter larger than the inner diameter of the second through hole 6, and the end of the capillary 1 on the side of the optical fiber strand inlet 3 is press-fitted, An optical fiber holding member 8 is formed.

  Then, the coating 10 at the tip is removed from the optical fiber holding member 8, and the optical fiber 11 with the optical fiber 9 exposed is inserted from the second through-hole 6 side. The alignment pad 12 shown in FIG. 1C is attached to the optical fiber 9 of the optical fiber 11 in advance before being inserted into the optical fiber holding member 8. Then, the optical fiber 11 is inserted into the pipe portion 5 and the capillary 1 until the tip of the optical fiber 9 protrudes from the first through hole 2 of the capillary 1. Finally, an adhesive is injected in the same manner as the optical fiber holding member 8 in FIG. 1A to fix the optical fiber 11, thereby completing the optical fiber pigtail 200.

  Further, an optical element is attached to the optical fiber pigtail 200 as necessary. In FIG. 2, the optical isolator element 24 is an example including a polarizer 21, a Faraday rotator 22, and an analyzer 23. After rotating and aligning in advance so that the angle of the transmission polarization plane of the polarizer 21 and the analyzer 23 is 45 °, the polarizer 21 and the analyzer 23 are bonded to the Faraday rotator 22 with an adhesive, and then the optical isolator element 24 has a predetermined size. It is formed by cutting. Since the entrance surface and the exit surface of the optical isolator element 24 are installed in parallel with, for example, a surface having an inclination angle of 8 ° of the end face 4 of the capillary 8, the surfaces are inclined at an angle of 8 ° with respect to the optical axis. As shown in FIG. 2, the side surface of the optical isolator element 24 (the surface between the entrance surface and the exit surface) is parallel to the optical axis when the optical isolator element 24 is installed on an inclined surface. If formed, the optical isolator element 24 can be accommodated in a compact manner. Further, the direction of the transmission polarization plane can be distinguished from the angle formed by the incident surface and the side surface.

  The cylindrical magnet 25 that applies a magnetic field to the Faraday rotator 22 is preferably set to have an outer diameter equal to or smaller than 2 mm, which is the minimum outer diameter of the optical fiber holding member 8 that is generally used. . Such a magnet 25 is fixed to the end surface of the pipe 5 with an adhesive so as to surround the optical isolator element 24 arranged inside the cylinder. The optical isolator element 24 and the magnet 25 constitute an optical isolator 26. As described above, the optical fiber pigtail 200 with an optical isolator is less likely to break the optical fiber under the high-temperature and high-humidity test condition in the optical fiber pigtail 200, and can improve long-term reliability.

  FIG. 3 is a longitudinal sectional view showing an embodiment of the optical element module 300 of the present invention. An optical element module 300 according to an embodiment of the present invention includes an optical unit 35 including a light emitting element 31 such as an LD, a lens 32, a stem 33, and an electronic cooling element 34, a case 36 that houses the optical unit 35, and an optical fiber. A first holder 37 for holding the pigtail 200 and an optical fiber pigtail 200 having one end portion inserted and fixed to the first holder are provided. The case 36 may contain a monitor PD (photodiode) or the like, but the monitor PD and its wiring lead are not shown.

  The optical unit 35 mounts and fixes the light emitting element 31 on the stem 33 by soldering, mounts a lens 32 for condensing the light emitted from the light emitting element 31 on the stem 33 by solder or YAG laser, and the stem 33 is an electronic cooling element. It is formed by mounting and fixing on 34 with solder. The optical unit 35 is accommodated in a case 36 and fixed with solder or the like.

  Further, in the optical fiber pigtail 200, the optical fiber holding member 8 is inserted into the first holder 37, and the flange portion 37a of the first holder 37 is made of a stainless alloy or Fe—Ni alloy provided in the case 36. The two holders 38 are mated. Next, after adjusting the first holder 37 and the optical fiber pigtail 200 in the XYZ directions and adjusting the position so that the optical signal emitted from the optical unit 35 is optically coupled to the optical fiber 11 of the optical fiber pigtail 200, The optical element module 300 is completed by welding the flange portion 37a of the first holder 37 to the second holder 38 and the optical fiber holding member 8 of the optical fiber pigtail 200 to the first holder 37 by YAG laser. Since such an optical element module 300 includes the optical fiber pigtail 200, the optical fiber is not easily broken under a high-temperature and high-humidity test condition, and long-term reliability can be improved.

  An optical fiber pigtail 200 shown in FIG. 2 was produced.

  A capillary 1 made of zirconia ceramics having an outer diameter of 1.4 mm and a length of 3 mm was produced. The capillary 1 has an angle formed between the first through hole 2 having a diameter of 0.126 mm at the center axis position and an axial direction of the first through hole 2 with an opening of about 1.0 mm at one end where the optical fiber 9 is introduced. Is provided with an optical fiber strand introduction port 3 having a conical shape of approximately 45 °.

  The pipe 5 made of a stainless alloy has an outer diameter of 2.0 mm, a length of 10 mm, a second through hole 6 having a diameter of 1.0 mm in the central axis direction, and a depth of 2 mm and a diameter of 1. mm at one end where the capillary 1 is press-fitted. A 4 mm counterbore part 7 was provided. And the optical fiber holding member 8 was produced by press-fitting the optical fiber strand inlet 3 side of the capillary 1 into the counterbore 7 of the pipe 5.

  The alignment pad 12 is made of the same zirconia ceramics as the capillary 1 and has a conical shape with an outer diameter of 1.0 mm and a vertex angle of 90 °, and a third through hole having a diameter of 0.126 mm from the center of the bottom surface toward the vertex. 13 was opened, and a slit 14 having the same width as the diameter of the third through hole 13 was provided from the third through hole 13 to the outer peripheral surface.

  The optical fiber 11 was made by removing about 20 mm from one end of an optical fiber coating 10 having an outer diameter of 0.9 mm and a length of about 1 m to form 9 parts of an optical fiber.

  The alignment pad 12 was attached to the optical fiber strand 9 through the slit 14 from the side of the optical fiber strand 9 with the bottom surface side of the alignment pad 12 facing the optical fiber coating 10 side. Next, the optical fiber strand 9 was inserted from the second through hole 6 side of the optical fiber holding member 8. The alignment pad 12 was fitted into the optical fiber introduction port 3, and the adhesive was injected from the second through-hole 6 side while holding the optical fiber 11 where the optical fiber coating 10 stopped against the alignment pad 12. At the same time, suction was performed from the end face 4 side of the capillary 1 and the adhesive was filled in the entire area from the second through hole 6 to the first through hole 1 of the optical fiber holding member 8. Thereafter, it was put into a constant temperature bath at 80 ° C. to cure the adhesive.

  After curing the adhesive, the excess optical fiber 9 protruding from the end face 4 of the capillary 1 was cut, and the end face 4 of the capillary 1 was obliquely polished at 8 ° to complete the optical fiber pigtail 100.

  The conventional optical fiber pigtail 500 and the optical fiber pigtail 200 according to this embodiment are put into a high-temperature and high-humidity tester having a temperature of 85 ° C. and a humidity of 85%, and the optical fiber wire inlet 3 in the optical fiber holding member 8 is inserted. The rate of optical fiber breakage was confirmed. The optical fiber breakage was confirmed by a precision reflectometer that introduced light into the optical fiber and could identify the reflectance and position if there was a breakage. The results are shown in Table 1.

  In the conventional optical fiber pigtail 500, an optical fiber breakage occurs at about 50% after 2,000 hours of 85 ° C.-85% high-temperature and high-humidity tester is introduced. As a result, the fracture occurrence rate of the optical fiber 11 was zero. By providing the alignment pad 12 at the optical fiber introduction port 3, the volume of the adhesive reservoir at the position of the optical fiber introduction port 3 is significantly reduced compared to the conventional one, and the adhesive generated under high temperature and high humidity conditions is reduced. It is considered that the optical fiber 11 could be prevented from being broken because the stress on the optical fiber 9 due to swelling was relaxed.

DESCRIPTION OF SYMBOLS 1 ... Capillary 2 ... 1st through-hole 3 ... Optical fiber strand introduction port 5 ... Pipe 6 ... 2nd through-hole 7 ... Seating part 8 ... Optical fiber holding member 9 ... Optical fiber strand 10 ... Optical fiber coating 11 ... Optical fiber 12 ... Alignment pad 13 ... Third through hole 14 ... Slit 21 ... Polarizer 22 ... Faraday rotator 23 ... Analyzer 24 ... Optical isolator element 25 ... Magnet 26 ... Optical isolator 31 ... Light emitting element or light receiving element 32 ... Lens 33 ... Stem 34 ... Electronic cooling element 35 ... Optical unit 36 ... Case 37 ... First holder 37a ... Flange 38 ... Second holder

Claims (6)

A first through hole formed on one end side, a second through hole formed on the other end side and having a diameter larger than the first through hole connected to the first through hole, and the first through hole An optical fiber holding member having an optical fiber strand introduction port formed so as to connect the two to the second through hole and having a diameter extending from the first through hole toward the second through hole; ,
An alignment pad disposed inside the optical fiber introduction port and having a third through hole having the same inner diameter as the first through hole;
An optical fiber comprising: an optical fiber that is inserted from the second through hole of the optical fiber holding member and holds an optical fiber in the first through hole and the third through hole. Pigtail. 2. The optical fiber pigtail according to claim 1, wherein the alignment pad has a slit formed from an outer peripheral surface to a center portion instead of the third through hole. The optical fiber holding member includes a capillary having the first through-hole and holding the optical fiber, a pipe having the second through-hole, and the capillary being inserted and held at one end. The optical fiber pigtail according to claim 1 or 2, characterized by comprising: 4. The optical element is bonded to an end surface having the opening of the first through hole on the one end side so as to cover the opening of the first through hole. 5. The described fiber optic pigtail. The optical fiber pigtail according to claim 4, wherein the optical element is an optical isolator element, and a magnet is bonded to an end face of the one end portion around the optical isolator element. An optical fiber pigtail according to any one of claims 1 to 5,
An optical module comprising a cylindrical first holder into which one end of the optical fiber holding member is inserted, and a case for housing a light emitting element optically coupled to the optical fiber on the one end.

Images