JP2008276201A - Optical fiber pigtail and optical module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pigtail and an optical module that reduce influence of noise and that excel in long term reliability of joining strength. <P>SOLUTION: The optical fiber pigtail includes a cylindrical body 10 in which one end of an optical fiber 12 is inserted into an inner hole and a cylindrical holder into which at least a part of the cylindrical body 10 is inserted. The holder is characterized in that it includes a metal-made cylindrical first holder 13 which is arranged on one end side in the axial direction of the holder and an electrically insulated second holder 14 which is arranged on the other end side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical fiber pigtail and an optical module, and more particularly to an optical fiber pigtail and an optical module for optical communication.

  Conventionally, an optical module for converting an optical signal into, for example, an electric signal has been developed. Such an optical module includes an optical element such as a laser diode or a photodiode and an optical fiber for conducting an optical signal. The optical module is configured to introduce or derive the optical signal through the optical fiber by placing the optical element opposite to the end surface of the optical fiber and allowing the optical signal to enter (or exit from) the end surface. Has been.

  FIG. 5 is a cross-sectional view of an optical fiber pigtail 111 according to the prior art, and FIG. 6 is a cross-sectional view showing an optical module including the optical fiber pigtail 111 according to the prior art. A conventional optical fiber pigtail 111 includes a cylindrical body 100, a metal holder 103, and an optical fiber 102.

  In the optical fiber pigtail 111, a cylindrical body 100 made of a ceramic material is press-fitted and fixed to a metal holder 103, and an optical fiber 102 is inserted into an inner hole 101 of the cylindrical body 100 and inserted into a through hole of the holder 103. The adhesive 105 is fixed (see, for example, Patent Document 1).

Also, as shown in FIG. 6, in the conventional optical module, after joining a metal sleeve 201 to the holder 103 of the optical fiber pigtail 111 by welding, the optical element 206 and the lens 204 are connected via the sleeve 201. It is configured by joining and fixing the housing 205 of the optical element unit 5 including the housing 205 by welding. In this case, an optical signal can be exchanged using the optical connector 106 attached to the opposite end.
JP 2004-20754 A

  However, in the conventional optical fiber pigtail 111, since the entire holder 103 is made of metal and has a structure protruding from the housing 205, the holder 103 serves as a receiving unit (antenna) and external noise waves (from the outside) In some cases, the noise radio wave affects the receiving sensitivity of the photodiode.

  Also, if the optical fiber pigtail holder is made of a non-metallic material such as resin or ceramics, it becomes difficult to bond the optical fiber pigtail holder and the housing by welding or soldering. There is. However, when bonding is performed with an adhesive, the adhesive has a possibility of lowering reliability in that the adhesive is weak in humidity and the adhesive strength deteriorates with time.

  Accordingly, an object of the present invention is to provide an optical fiber pigtail and an optical module that reduce the influence of noise and are excellent in long-term reliability of bonding strength.

  An optical fiber pigtail according to the present invention has a cylindrical body in which one end portion of an optical fiber is inserted into an inner hole, and a holder in which at least a part of the cylindrical body is inserted. A cylindrical first holder made of metal disposed on one end side in the axial direction of the holder, and a second holder having electric insulation disposed on the other end side To do.

  Further, in the present invention, the cylindrical body has a distal end side inserted into the first holder, a rear end side inserted into the second holder, and a distal end portion protruding from the first holder. It is preferable that

  In the present invention, the second holder is preferably made of ceramics.

  Moreover, in this invention, it is preferable that the said 1st holder and a 2nd holder are connected, and the said cylinder is inserted only in the said 1st holder.

  In the present invention, the second holder is preferably made of resin.

  Furthermore, in the present invention, the resin preferably has translucency.

  Furthermore, in the present invention, it is preferable that the length of the first holder in the longitudinal direction is shorter than the length of the second holder in the longitudinal direction.

  Still further, the cylindrical body has a groove portion that communicates with the inner hole from the outer peripheral surface, and includes an optical isolator element and a magnet that covers the isolator element in the groove portion, and the groove portion is located inside the second holder. The second holder is preferably made of a non-magnetic material.

  An optical module of the present invention includes the above-described optical fiber pigtail, an optical element that emits light toward the optical fiber, or that receives light derived through the optical fiber, and the optical element. The optical fiber pigtail includes a first holder and a housing joined via a sleeve to be welded.

  According to the optical fiber pigtail and the optical module according to the present invention, the conductive portion that is constituted by the electrically insulating material and the metal holder and reduces the metal holder portion, the conductive portion that becomes the noise receiving portion (antenna) is obtained. Therefore, the influence of noise received from the surroundings can be reduced, and at least the metal part is included, so that the part of the holder and the housing of the optical module can be connected by, for example, laser welding or soldering firmly. It becomes possible to join and fix to.

  Therefore, according to the present invention, it is possible to provide an optical fiber pigtail and an optical module that reduce the influence of noise and are excellent in long-term reliability of bonding strength.

  Hereinafter, an optical fiber pigtail and an optical module including the same according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a sectional view of an optical fiber pigtail 1 according to a first embodiment of the present invention. In addition, the optical connector 16 in a figure is a side view.

  The optical fiber pigtail 1 according to the first embodiment includes an optical fiber 12, a cylindrical body 10 in which one end portion of the optical fiber 12 is inserted into the inner hole 11, and a part of the cylindrical body 10 is inserted. A holder, an adhesive 15 filled in the holder, and an optical element bonded to one end surface of the cylindrical body 10 are provided. The holder includes a cylindrical first holder 13 made of a weldable metal and a cylindrical second holder 14 having electrical insulation. The optical connector 16 shown on the left side of FIG. 1 is not necessarily required as a component of the invention, but is attached to put light into and out of the optical fiber 12.

  In the optical fiber pigtail 1 according to the first embodiment, the first holder 13 and the second holder 14 have the same diameter, are arranged coaxially, and the first holder 13 and the second holder 14. The cylindrical body 10 is inserted into the through holes of the first holder 13 and the second holder 14 so that the cylindrical body 10 is in contact with both. The first holder 13 and the second holder 14 are preferably arranged on the same axis, but need not be on the same axis. Moreover, although it is preferable that the 1st holder 13 and the 2nd holder 14 have the same diameter, it does not necessarily need to be the same diameter also about this.

  In the optical fiber pigtail 1, the second holder 14 made of an electrically insulating material is incorporated in the holder to reduce the conductive portion (the first holder 13) that becomes a noise receiving portion (antenna). Thus, the influence of noise received from the surroundings can be reduced. Further, since the first holder 13 made of a metal material is incorporated in a part of the holder, for example, the metal housing of the optical module and the first holder 13 are firmly bonded and fixed by laser welding or soldering. Is possible. In the optical fiber pigtail according to the first embodiment, the first holder 13 and the second holder 14 do not need to be in contact with each other and may be separated to some extent.

  The cylindrical first holder 13 has an inner hole 13b into which the cylindrical body 10 is inserted. The cylindrical body 10 and the first holder 13 are fixed by adhesion or press-fitting, but are preferably press-fitted and fixed from the viewpoint of reliability. The first holder 13 is a member for joining the optical element unit 4 and the optical fiber pigtail 1 when creating an optical module. As a material constituting the first holder 13, a metal material such as stainless steel, copper, iron and nickel is used, and stainless steel materials such as SUS304 and SF20T which are excellent in YAG weldability are particularly suitable. In the present invention, the metal material includes not only a simple metal but also an alloy.

  The cylindrical second holder 14 has a function of protecting the optical fiber 12 by bonding and fixing the covering portion of the optical fiber 12 with the adhesive 15. The second holder 14 is bonded or press-fitted and fixed to the cylindrical body 10. As the material of the second holder, synthetic resin (such as thermoplastic resin and thermosetting resin), ceramics (such as aluminum oxide (alumina) and zirconium oxide (zirconia)), glass (such as quartz), and the like are used. As the thermoplastic resin, nylon resin, liquid crystal polymer resin, polyacetal resin, polybutylene terephthalate resin, polyetherimide resin, polycarbonate resin, etc. are used, and as the thermosetting resin, epoxy resin, urea resin, etc. are used. . In order to increase the mechanical strength, fillers such as glass fibers and glass particles may be added.

Among these materials, zirconia-based ceramics (ceramics mainly composed of zirconia) excellent in weather resistance and toughness are preferable. Further, among zirconia ceramics, zirconium oxide (ZrO ₂ ) as a main component and at least one selected from the group consisting of Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like as a stabilizer. The partially stabilized zirconia ceramics (mainly tetragonal crystals) are preferred from the viewpoints of wear resistance and elastic deformation. By using ceramics, it is possible to fix the second holder 14 using press-fitting, and the fixing strength of the second holder 14 with respect to the cylindrical body 10 can be improved. According to such a form, for example, even in a severe test environment such as a mechanical test such as a vibration test and an impact test defined by a standard such as Telcordia, a high temperature and high humidity test, and a temperature cycle test. Sufficient durability is obtained.

  If the material of the second holder 14 is resin, the cylinder 10 and the second holder 14 may be fixed using insert molding when the second holder 14 is molded. By insert molding, the cylindrical body 10 and the second holder 14 can be fixed simultaneously with the production of the second holder 14. Further, if the second holder 14 is made of resin, it is advantageous from the viewpoint of cost reduction.

  The cylindrical body 10 is a columnar member having an inner hole 11 extending in the axial direction (longitudinal direction) of the cylindrical body 10. An optical fiber 12 is inserted into the inner hole 11 and is fixedly bonded with an adhesive 15. The end surface 10 a of the cylinder 10 is inclined at a predetermined angle (for example, 4 to 10 °) with respect to the axis of the cylinder 10. Such a configuration is suitable, for example, for preventing light emitted from an optical element (such as an LED or LD) from being reflected by the end face of the optical fiber 12 and returning to the optical element as reflected light.

Examples of the material constituting the cylindrical body 10 include zirconium oxide (zirconia), aluminum oxide (alumina), mullite, silicon nitride, silicon carbide, aluminum nitride and the like, ceramics containing these as main components, and glass such as crystallized glass. Metals such as ceramics, phosphor bronze, beryllium copper, brass, and stainless steel, plastics such as epoxy and liquid crystal polymer are used, and zirconia-based ceramics (ceramics mainly composed of zirconia) with excellent weather resistance and toughness are particularly suitable. It is. Further, among zirconia ceramics, zirconium oxide (ZrO ₂ ) as a main component and at least one selected from the group consisting of Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like as a stabilizer. The partially stabilized zirconia ceramics (mainly tetragonal crystals) are preferred from the viewpoints of wear resistance and elastic deformation. The end surface 10 a of the cylindrical body 10 preferably has a structure protruding from the end surface 13 a of the first holder 13. According to such a configuration, it is possible to perform optical polishing suitable for the end surface 10a without damaging the first holder 13 so that light incident on or emitted from the optical fiber 12 is transmitted without scattered light. .

  The optical fiber 12 is for conducting (propagating) light. As the optical fiber 12, a quartz optical fiber, a plastic optical fiber, a multicomponent glass optical fiber, or the like is used. The optical fiber 12 includes a bare fiber portion of the optical fiber and a covering portion that protects the optical fiber. The bare fiber portion of the optical fiber is inserted and fixed in the inner hole 11 of the cylindrical body 10, and the covering portion is the second holder. It is fixed via an adhesive 15 in 14 inner holes 14b.

  As the adhesive 15, from the viewpoint of securing sufficient bonding strength, an ultraviolet curable epoxy resin, a thermosetting epoxy resin, an epoxy resin used in combination with an ultraviolet ray and a thermosetting, an ultraviolet curable acrylic resin, a thermosetting acrylic resin, and an ultraviolet curable polyimide. A resin, a thermosetting polyimide resin, or the like is used, and most preferably a thermosetting epoxy resin.

  The optical connector 16 is attached to put light into and out of the optical fiber pigtail 1. Such an optical connector 16 is not particularly limited, but an optical connector described in JIS C 5970-5984 is desirable.

  The optical fiber pigtail 1 according to the present embodiment includes an electrically insulating member. Therefore, in the optical fiber pigtail 1, it is possible to reduce the proportion of the conductive portion (typically a portion made of metal) in the optical fiber pigtail 1. Therefore, in the optical fiber pigtail 1, the conductive portion that becomes the noise receiving portion (antenna) can be reduced, so that the influence of noise received from the surroundings can be reduced.

  As a manufacturing method of the optical fiber pigtail 1 of the present invention, for example, after fixing the cylindrical body 10 to the first holder 13, the second holder 14 is fixed and the optical fiber 12 is bonded using the adhesive 15. After that, the end face 10a can be realized by polishing obliquely using a polishing film such as diamond.

(Second Embodiment)
FIG. 2 is a sectional view of an optical fiber pigtail 1 ′ according to the second embodiment of the present invention. In addition, the optical connector 16 in a figure is a side view.

  In the first embodiment, the cylindrical body 10 is in contact with the first holder 13 and the second holder 14, whereas in the second embodiment, the cylindrical body 10 is only on the first holder 13. Other configurations are the same, though different in the point of contact. In the second embodiment, since the axial length of the cylindrical body 10 can be shortened and the bonded portion of the optical fiber 12 can be lengthened, the adhesive strength of the optical fiber 12 can be increased. Further, in the optical fiber pigtail 1 ′, since the first holder 13 is configured to be shorter than the length in the longitudinal direction of the second holder, the metal portion can be shortened, so that the noise receiving unit (antenna) Therefore, the influence of noise received from the surroundings can be reduced.

  In this case, the first holder 13 and the second holder 14 are connected and fixed to each other at the end face 14a. As a fixing method, for example, press-fit fixing as shown in FIG. 2 or adhesive fixing in which the end surfaces of the first holder 13 and the second holder 14 are bonded with an adhesive or the like is available. The cylindrical body 10, the first holder 13, and the second holder 14 are made of the same material as that of the first embodiment, but the second holder 14 is preferably made of resin. In particular, by using a translucent resin, when bubbles or the like are contained in the adhesive 15, it can be visually confirmed. When the temperature cycle test is performed, the bubbles in the adhesive 15 repeatedly expand and contract, causing damage to the bare fiber portion of the optical fiber 12. As the translucent resin, thermoplastic nylon resin, liquid crystal polymer resin, polyetherimide resin and polycarbonate resin are used, and as the thermosetting resin, epoxy resin, urea resin, or the like is used. Therefore, if a translucent resin is used for the second holder 14, it can be assembled while visually confirming the presence or absence of bubbles and foreign matters, so that the introduction of defective products can be prevented.

  If the material of the second holder 14 is resin, the first holder 13 and the second holder 14 are fixed by using insert molding when the second holder 14 is molded. Also good. By performing the insert molding, the first holder 13 and the second holder 14 can be fixed simultaneously with the production of the second holder 14.

  The influence of noise can be reduced as the conductive portion is shorter. Therefore, the influence of noise can be reduced by reducing the length of the first holder in the longitudinal direction and the length of the second holder in the longitudinal direction. Can be further reduced.

(Third embodiment)
3A and 3B show an optical fiber pigtail 1 ″ according to a third embodiment of the present invention, in which FIG. 3A is a cross-sectional view and FIG. 3B is a top view. In addition, the optical connector 16 in the figure is a side view.

  In the third embodiment, a groove portion 51 communicating with the outer peripheral surface of the cylindrical body 10 and the inner hole 11 is formed in the inner portion of the second holder 14, and the optical isolator element 52 and the magnet 54 are formed in the groove portion 51. Is different from the optical fiber pigtail 1 of the first embodiment in that it is installed.

  The groove 51 formed in the cylindrical body 10 is a portion where the optical isolator element 52 and the magnet 54 are disposed, and the bottom surface is a flat surface. The width of the groove 51 in the axial direction of the cylinder 10 is set according to the size of the optical isolator element 52 and the magnet 54 to be arranged, but the length of the optical isolator element 52 and the magnet 54 in the axial direction of the cylinder 10. If it is 1.05-1.3 times than this, an element and a magnet are easily mounted and it is suitable from a viewpoint that the bending strength of the cylinder 10 can be maintained. In the present embodiment, as shown in FIG. 3A, a through hole that communicates with the groove 51 of the cylindrical body 10 is provided in the second holder 14. With such a configuration, the positions of the optical isolator element 52 and the magnet 54 can be finely adjusted from the through hole, so that the alignment can be performed with high accuracy.

The optical isolator element 52 has a structure in which a Faraday rotator is sandwiched between a pair of polarizers, and has a function of transmitting only light in one direction. The polarizer, the Faraday rotator, and the polarizer are flat plates having a thickness of 0.2 to 6 mm, and those having a size of about 0.2 to 0.6 mm square are used. The polarizer is composed of a polarizing plate or a birefringent crystal that absorbs a polarization component perpendicular to the transmission polarization direction composed of a glass substrate containing dielectric particles or a laminate of dielectrics, and a diffraction grating. It is possible to use a reflection type utilizing the light, a polarizing plate that shifts the optical path, or the like. As the material of the Faraday rotator, Bi-substituted garnet or YIG garnet to which Tb, Gd, or Ho is added can be used. Further, the surface of the Faraday rotator 3 is composed of a multilayer film such as TiO ₂ / SiO ₂ or Ta ₂ O ₅ / SiO _2, and forms an antireflection film having a light reflection amount of 0.2% or less. May be.

  In the optical fiber pigtail 1 ″, a translucent resin 53 is filled between the optical isolator element 52 and the side surface of the groove 51 where the end face of the optical fiber is exposed. This translucent resin 53 has a function of reducing the loss of light generated between the optical fiber 12 and the optical isolator element 52. As a material of such a translucent resin 53, for example, an epoxy resin, an acrylic resin, a silicon resin, or the like is used. From the viewpoint of reducing light loss, a quartz single is used as the optical fiber 12. If a mode fiber is used, a resin having a refractive index of about n = 1.44 to 1.48 is preferable.

  The magnet 54 has a function of applying a magnetic field to the Faraday rotator to promote the Faraday effect of the Faraday rotator. Therefore, two magnets 54 are arranged so as to sandwich the Faraday rotator. Examples of such magnets 54 include neodymium magnets and samarium cobalt magnets, but samarium cobalt magnets are preferred from the viewpoint of high magnetic flux density and efficient generation of the Faraday effect.

  The optical isolator element 52 and the magnet 54 are fixed to the bottom surface of the groove 51 with an adhesive. Examples of such an adhesive include an acrylic resin and an epoxy resin, and an ultraviolet curing type, a thermosetting type, or a combination thereof is used as a curing method.

  Further, in the optical fiber pigtail 1 ″, the second holder 14 is made of a nonmagnetic material. Examples of the material constituting the second holder include synthetic resin, ceramics (such as aluminum oxide (alumina) and zirconium oxide (zirconia)), and glass (such as quartz). As the synthetic resin (thermoplastic resin), nylon resin, liquid crystal polymer resin, polyacetal resin, polybutylene terephthalate resin, polyetherimide resin and polycarbonate resin are used, and as the synthetic resin (thermosetting resin), epoxy resin is used. Or urea resin is used. Further, these synthetic resins may be added with fillers such as glass fibers and glass particles in order to increase the mechanical strength.

  As described above, the optical fiber pigtail 1 '' according to the present embodiment includes the optical isolator element 51 and the magnet 54 inside the second holder 14 made of a nonmagnetic material. The member (for example, the first holder) to be formed has a structure in which the magnetic flux generated from the magnet 54 is difficult to be taken away. Therefore, in the optical fiber pigtail 1 ″, the magnetic field generated from the magnet 54 can be efficiently applied to the Faraday rotator. Furthermore, when the optical fiber pigtail 1 ″ is incorporated in the optical module, the entire optical module can be reduced in size as compared with the configuration in which the optical isolator element is provided on the end face of the first holder 13. In addition, when the optical fiber pigtail 1 ″ is used in an optical module, a decrease in magnetic field can be reduced even if the optical module housing is made of a magnetic material.

(Fourth embodiment)
FIG. 4 shows a cross section of an optical module 50 including the optical fiber pigtail 1 according to the present invention. The optical module 50 according to the third embodiment includes the optical fiber pigtail 1 and the optical element unit 40 according to the second embodiment. The optical element unit 40 includes an optical element 46, a lens 44, and a housing 45.

  The optical element 46 is a light emitting element for emitting light toward the optical fiber 12 of the optical fiber pigtail 1 or a light receiving element for receiving light derived via the optical fiber 12 of the optical fiber pigtail 1. It is. As the light emitting element, a light emitting diode such as a semiconductor laser or an LED is used, and as the light receiving element, a receiving PD (photodiode) is used.

  When the optical element 46 is a light emitting element, the lens 44 has a function of condensing the light emitted from the light emitting element and introducing it into the optical fiber 12 of the optical fiber pigtail 1, and when the optical element 61 is a light receiving element. Is a member responsible for the function of condensing light introduced through the optical fiber 12 of the optical fiber pigtail 1 and introducing it into the light receiving element.

  The housing 45 is a member for housing the optical element 46 and the lens 44, and is joined and fixed to the optical fiber pigtail 1 by welding, for example. As the material constituting the housing 45, weldable materials such as stainless steel, copper, iron, nickel and the like can be used, and stainless steel is particularly preferable from the viewpoint of corrosion resistance and weldability.

  The optical fiber pigtail 1 and the optical element unit 40 are firmly fixed to each other via the sleeve 41 by welding. By fixing by welding, sufficient joint strength can be secured. For example, mechanical strength tests such as vibration tests and impact tests defined by standards such as Telcordia, high temperature and high humidity tests, and temperature cycles Sufficient durability can be obtained even in a severe test environment such as a test.

  As the material constituting the sleeve 41, metal materials such as stainless steel, copper, iron and nickel are used, and stainless steel materials such as SUS304 and SF20T which are excellent in YAG weldability are particularly suitable.

  The optical module 50 may have an optical isolator element 42 that suppresses return light to the light source for emitting light toward the cylindrical body 10 on the end surface 10 a side of the cylindrical body 10. In that case, the optical isolator element 42 is fixed to the end face 10 a of the cylinder 10, the magnet 43 is fixed to the end face 13 a of the first holder 13, and the optical isolator element 42 is disposed in the inner hole 11 of the magnet 43. It has become. Further, the optical module of the present invention is not limited to the above-described form of the optical module 50, and may be, for example, an optical module including the above-described optical fiber pigtail 1 ''.

  As mentioned above, although embodiment of this invention was shown, this invention is not limited to this, A various change is possible within the range which does not deviate from the technical idea of this invention.

  Next, examples and comparative examples of the present invention will be described.

[Embodiments of the present invention]
<Fabrication of optical transceiver>
First, the cylindrical body 10 made of zirconia ceramic is press-fitted and fixed in the inner hole 13b of the first holder 13 made of SUS304, and then the second holder 14 made of PBT (polybutylene terephthalate) is bonded and fixed to the first holder 13. did. Next, the optical fiber 12 to which the F04 type optical connector described in JIS C 5973 was attached as the optical connector 16 was inserted into the inner hole 11 of the cylindrical body 10 and bonded and fixed using a thermosetting epoxy resin as the adhesive 15. Finally, the tip surface 10a was polished at an inclination angle of 6 degrees to produce the optical fiber pigtail 1.

  Further, by YAG welding a stainless steel housing having a spherical lens made of a semiconductor laser and a PD (photodiode) for reception and quartz glass as the optical element 46 to the obtained optical fiber pigtail 1. Then, an LD module and a PD module were manufactured, and these were placed in parallel in a plastic case to manufacture an optical transceiver according to this example.

<Reception sensitivity measurement test>
A DC power supply (trade name: PAB18-1A, manufactured by KIKUSUI) is attached to the optical transceiver of this embodiment so that the module can be driven, and a digital data analyzer (trade name: MP1630B, manufactured by Anritsu) is connected to pulse. Enabled to send and receive signals. Further, the LD module and the PD module were connected by a jumper cable having optical connectors arranged at both ends. As a result, the pulse signal transmitted from the digital data analyzer becomes an optical signal via the LD module, and this optical signal is transmitted from the jumper cable having the optical connector at both ends to the PD module and converted into the pulse signal again. Received by the data analyzer.

  Then, the bit error rate with respect to the input optical power of the optical transceiver according to the present embodiment was measured, and the result is shown in FIG.

[Comparative example]
<Fabrication of optical transceiver>
First, the cylinder 100 made of zirconia ceramics was press-fitted and fixed into the inner hole 103b of the first holder 103 made of SUS304. Next, the optical fiber 12 to which the F04 type optical connector described in JIS C 5973 was attached as the optical connector 106 was inserted into the inner hole 101 of the cylindrical body 100, and was bonded and fixed using a thermosetting epoxy resin as the adhesive 105. Finally, the end face 100a was polished at an inclination angle of 6 degrees to produce an optical fiber pigtail 111.

  Further, by YAG welding a stainless steel housing provided with a spherical lens made of a semiconductor laser and a receiving PD (photodiode) and quartz glass as the optical element 206 to the obtained optical fiber pigtail 111, An LD module and a PD module were produced, and these were placed in parallel in a plastic case to produce an optical transceiver according to this comparative example.

<Reception sensitivity measurement test>
A DC power supply (trade name: PAB18-1A, manufactured by KIKUSUI) is attached to the optical transceiver of the comparative example so that the module can be driven, and a digital data analyzer (trade name: MP1630B, manufactured by Anritsu) is connected to the pulse signal. Can be sent and received. Further, the LD module and the PD module were connected by a jumper cable having optical connectors arranged at both ends. As a result, the pulse signal transmitted from the digital data analyzer becomes an optical signal via the LD module, and this optical signal is transmitted from the jumper cable having the optical connector at both ends to the PD module and converted into the pulse signal again. Received by the data analyzer.

  Then, the bit error rate with respect to the input optical power of the optical transceiver according to this comparative example was measured, and the result is shown in FIG.

<Evaluation>
As shown in FIG. 7, compared with the optical transceiver of the comparative example, in the optical transceiver of the present invention, the bit error was reduced and the reception sensitivity was improved by about 0.25 dBm. From the above, the optical transceiver of the example was able to reduce the influence of noise received from the surroundings as compared with the optical transceiver of the comparative example.

It is sectional drawing of the optical pigtail which concerns on one Embodiment of this invention. It is sectional drawing which shows other embodiment of this invention. FIG. 4 shows another embodiment of the present invention, in which (a) is a cross-sectional view and (b) is a top view. It is sectional drawing of the optical module of this invention using the optical pigtail shown in FIG. It is sectional drawing of the optical pigtail which concerns on a prior art. It is sectional drawing of the conventional optical module using the optical pigtail shown in FIG. It is a graph which shows the measurement result regarding the input optical power and bit error rate in an optical transceiver.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1 ', 1''Optical fiber pigtail 40 Optical element unit 50 Optical module 10 Tubular body 10a End surface 11 Inner hole 12 Optical fiber 13 Holder 13a End surface 13b Inner hole 14 Holder 14a End surface 14b Inner hole 15 Adhesive 16 Optical connector 41 Sleeve 42 Optical Isolator 43 Magnet 44 Lens 45 Housing 46 Optical Element 51 Groove 52 Optical Isolator Element 53 Translucent Resin 54 Magnet

Claims (9)

A cylindrical body in which one end of an optical fiber is inserted into the inner hole;
A cylindrical holder into which at least a part of the cylindrical body is inserted,
The holder includes a cylindrical first holder made of metal disposed on one end side in the axial direction of the holder, and a second holder having electrical insulation disposed on the other end side. An optical fiber pigtail characterized by comprising:   The cylindrical body has a distal end side inserted into the first holder, a rear end side inserted into the second holder, and a distal end portion disposed so as to protrude from the first holder. The optical fiber pigtail according to claim 1.   The optical fiber pigtail according to claim 2, wherein the second holder is made of ceramics.   The optical fiber pigtail according to claim 1, wherein the first holder and the second holder are connected, and the cylindrical body is inserted only in the first holder.   The optical fiber pigtail according to claim 4, wherein the second holder is made of resin.   The optical fiber pigtail according to claim 5, wherein the resin has translucency.   The optical fiber pigtail according to any one of claims 1 to 6, wherein a length of the first holder in the longitudinal direction is shorter than a length of the second holder in the longitudinal direction. The cylindrical body has a groove portion that communicates with an inner hole from an outer peripheral surface, and includes an optical isolator element and a magnet that covers the isolator element in the groove portion, and the groove portion is disposed inside the second holder. And
The optical fiber pigtail according to any one of claims 1 to 7, wherein the second holder is made of a non-magnetic material. The optical fiber pigtail according to any one of claims 1 to 8,
An optical element that emits light toward the optical fiber or receives light derived through the optical fiber;
An optical module comprising: a housing that accommodates the optical element and is joined to the first holder of the optical fiber pigtail through a sleeve to be welded.

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