JP2005099493A - Optical receptacle and its assembling method, and optical connector and optical module using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical receptacle whose reliability is improved by improving a wiggle characteristic and preventing a sleeve from cracking. <P>SOLUTION: The optical receptacle, constituted by holding the sleeve 4 for pressing and fixing a rear end of a fiber stab 1 having an optical fiber 43 fixed in a through hole of a ferrule 2 in a holder 5 and holding a plug ferrule 10 connected to a front end surface of the fiber stub 1 at a tip part of the fiber stub 1, holding the outer periphery of the sleeve 6 by a sleeve case 6, and holding a rear end side of the outer periphery of the sleeve case 6 by the holder 5, has a clearance A between the rear end side of the outer periphery of the sleeve case 6 and the holder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical receptacle and an optical connector used for an optical communication module and the like, and a manufacturing method thereof.

  An optical module for converting an optical signal into an electrical signal has a structure in which an optical element such as a semiconductor laser or a photodiode is housed in a case, and the optical signal is introduced or derived through an optical fiber (Patent Document). 1).

  A receptacle-type optical module in which a connector is connected among the optical modules includes an optical element 22 at one end of an optical receptacle 14 as shown in FIG. 4 and a plug of an optical connector (SC connector or the like) at the other end. The ferrule 15 is connected.

  As shown in FIG. 4, the optical receptacle 14 includes a ferrule 17 made of a ceramic material such as zirconia or alumina, and a fiber stub obtained by inserting and fixing an optical fiber 18 made of quartz glass or the like in a through hole of the ferrule 17. The rear end of 16 is fixed to the holder 20 by press-fitting, the front end is inserted into the inner hole of the sleeve 19, and they are press-fitted or adhesively fixed to the sleeve case 21.

  Further, the sleeve case 21 is fixed by press-fitting the rear end side thereof into the holder 20, and therefore the inner diameter D2 of the insertion portion 19a for guiding the plug ferrule 15 to the sleeve 19 in the sleeve case 21 is larger than the inner diameter D1 of the sleeve 19. Is set large, and is press-fitted or bonded and fixed so as not to interfere with the inner diameter D1 of the sleeve 19.

  At this time, the outer diameter of the ferrule 17 is about φ2.5 mm for the type connecting the SC connector, about φ1.25 mm for the small type connecting the LC connector, and the outer diameter tolerance is ± 1 μm or less. The optical fiber 18 provided in the hole has an outer diameter of about 125 μm and an outer diameter tolerance of about ± 1 μm, which is defined by JIS standards, IEC standards, etc. The sleeve 19 and the ferrule 17 are processed with high precision so that the cores (not shown) having a diameter of about 10 μm that propagate the signal are connected to each other with little loss. The sleeve 19 stabilizes the fiber stub 16 and the plug ferrule 15. In addition, the structure is held with high accuracy.

Further, the end face of the optical fiber 18 in the fiber stub 16 is mirror-polished to a curved surface having a curvature radius of about 5 to 30 mm in order to reduce the connection loss at the time of contact, and the opposite end face is an optical element such as an LD. In order to prevent the light emitted from the optical fiber 18 from being reflected at the tip of the optical fiber 18 and returning to the optical element, it is mirror-polished to an inclined surface of about 4 to 10 ° together with the ferrule 17 inserted through the optical fiber 18. Yes.
JP 2001-66468 A

  However, in recent years, the output stability (wiggle characteristics) of the optical communication module with respect to the load applied to the plug ferrule in the direction perpendicular to the optical axis has been regarded as important. With the conventional structure shown in FIG. It has such a direct structure.

  This is because the conventional optical receptacle 14 as shown in FIG. 4 is press-fitted and bonded and fixed so that the outer periphery of the rear end side of the sleeve case 21 is covered with the holder 20. Therefore, in order to prevent interference between the inner diameter D2 of the sleeve case 21 and the inner diameter D1 of the sleeve 19, D2 must be set to be considerably larger than D1.

  Therefore, the force due to the load applied to the plug ferrule 15 in the direction perpendicular to the optical axis is directly applied to the sleeve 19, and the sleeve 19 is easily deformed until it contacts the inner diameter D <b> 2 of the sleeve case 21. As a result, there has been a problem that the PC joint of the optical fiber fixed to the optical fiber 18 and the plug ferrule 15 is easily detached, and the reflection at the joint or the connection loss is deteriorated. There was a problem that the sleeve was cracked by the load.

  In view of the above, the optical receptacle of the present invention holds the plug ferrule connected to the front end surface of the fiber stub while pressing and fixing the rear end portion of the fiber stub formed by fixing the optical fiber in the through hole of the ferrule to the holder. An optical receptacle in which a sleeve for holding the fiber sleeve is held at the tip of the fiber stub, the outer periphery of the sleeve is held by a sleeve case, and the rear end side of the sleeve case outer periphery is held by a holder. An optical receptacle characterized by having a clearance between the rear end side and the holder, reducing the difference between the inner diameter of the sleeve case and the inner diameter of the sleeve, and preventing the inner diameter of the sleeve case from interfering with the inner diameter of the sleeve. After being adjusted, the optical receptacle is fixed by adhesive, solder or welding A.

  According to the optical receptacle of the present invention, the rear end portion of the fiber stub in which the optical fiber is inserted and fixed in the through-hole of the ferrule is fixed to the holder, and the sleeve for holding the plug ferrule connected to the front end surface of the fiber stub is provided. In the optical receptacle formed by holding the tip of the fiber stub, the inner diameter position of the sleeve case for introducing the plug ferrule can be fixed after being adjusted in the direction perpendicular to the optical axis so as not to interfere with the inner diameter of the sleeve. Even if the difference between D2 and D1 is 50 μm or less, the inner diameters do not interfere with each other, so that the Uyghur characteristics can be greatly improved.

  At the same time, the amount of deformation of the sleeve can be suppressed, cracking of the sleeve can be prevented, and reliability can be improved.

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

  FIG. 1 is a cross-sectional view showing an embodiment of an optical receptacle of the present invention, in which a rear end portion of a fiber stub 1 formed by fixing an optical fiber 3 in a through hole of a ferrule 2 is press-fitted and fixed to a holder 5 and a fiber. A sleeve 4 for holding the plug ferrule 10 connected to the tip surface of the stub 1 is held at the tip of the fiber stub 1, the outer periphery of the sleeve 4 is held by the sleeve case 6, and the rear of the sleeve case 6 is The end side is held by the holder 5.

  Here, the optical receptacle 7 of the present invention is characterized by having a clearance A between the rear end side of the outer periphery of the sleeve case 6 and the holder 5.

  With this clearance A, the sleeve case 6 and the holder 5 can be moved in the direction perpendicular to the optical axis of the optical fiber 3 to adjust the position. Therefore, even if the sleeve 4 inserted and fixed in the fiber stub 1 does not match the center of the inner diameter of the sleeve case 6, the position of the sleeve case 6 is moved and adjusted within the range of the clearance A so that the inner diameter centers of the sleeve case 6 and the sleeve case 6 match. When the optical connector and the optical module are manufactured using the optical receptacle 7, the optical fibers can be connected with high accuracy.

  In addition, this position adjustment is performed by, for example, observing the inner diameter of the sleeve 4 and the inner diameter of the sleeve case 6 with a camera from the plug ferrule 10 side so that the inner diameters do not interfere with each other. Welding can be performed.

  As an assembly method of the optical receptacle 7 having the clearance A as described above, as shown in FIG. 2, an adjustment pin 8 having an outer diameter equal to or larger than that of the plug ferrule 10 is inserted into the sleeve case 6 in advance. It is preferable that the adjustment pin 8 is inserted into the sleeve 4, and the tip portion of the fiber stub 1 is inserted into the sleeve 4 and positioned and fixed in that state.

  By this method, the sleeve case 6 can be easily fixed without interfering with the inner diameter of the sleeve 4 and the inner diameter of the sleeve 4.

  As shown in FIG. 1, the difference between the inner diameter D2 of the insertion portion 6a for guiding the plug ferrule 10 to the sleeve 4 and the inner diameter D1 of the sleeve 4 is reduced to a small value of 50 μm or less. Accurate position adjustment is possible. Therefore, even when the force due to the load applied to the plug ferrule 10 in the direction perpendicular to the optical axis is applied to the sleeve 4, the difference between the outer diameter of the plug ferrule 10 and the inner diameter D2 of the sleeve case 6 is small. 6 is in contact with the insertion portion 6a and even if the sleeve 4 is inserted into the sleeve 4, the deformation of the sleeve 4 becomes very small, and the optical fiber 3 and the optical fiber of the plug ferrule 10 are kept in the PC connection with each other. Reflection and connection loss fluctuations can be suppressed. Moreover, it can prevent effectively that the sleeve 4 deform | transforms with a load and a crack arises.

  The adjustment pin 8 is preferably made of ceramic in terms of insertability into the sleeve 4 and processing accuracy. As for the outer diameter, considering the insertability into the sleeve 4, the type connecting the SC connector is about φ2.500 to 2.510 mm, the type connecting the MU or LC connector is A diameter of about 1.250 to 1.260 mm is preferable.

  As the shape of the sleeve case 6 used in such an optical receptacle 7, as shown in FIGS. 3A, 3B, and 3C, the outer peripheral side of the holder 5 is arranged on the rear end side of the outer periphery of the sleeve case 6. It is preferable to form a brim portion 25 to be joined to the tip surface.

  For example, as shown in FIGS. 3A and 3B, the flange portion 25 forms a flange portion 25 protruding on the outer periphery at a predetermined distance from the rear end surface of the sleeve case 6. A flange 25 provided with a clearance A between the outer periphery on the rear end side of the flange portion 25 and the holder 5 or a flange portion 25 that projects the rear end surface of the sleeve case 6 on the outer periphery thereof as shown in FIG. By providing the clearance A between the rear end surface of the sleeve case 6 and the front end surface on the inner peripheral side of the holder 5, the concentricity between the sleeve 4 and the sleeve case 6 can be adjusted. The joining area of the sleeve case 6 and the holder 5 can be kept sufficiently, and stable joining can be performed.

  In addition, even if the sleeve case 6 is adjusted within the range of the clearance A, the outermost diameter of the flange portion 25 is set to be approximately equal to the outer diameter of the holder 5.

  Moreover, when it has the collar part 25, since the joint surface with the holder 5 can be confirmed easily and is surface contact, it is suitable for laser welding or soldering. In the case of laser welding, the material of the sleeve case 6 is preferably a material such as SUS304. In the case of soldering, the sleeve case 6 and the holder 5 are preferably plated with nickel, gold, or the like.

Here, the ferrule 2 constituting the fiber stub 1 is made of a metal such as stainless steel or phosphor bronze, an epoxy, a plastic such as a liquid crystal polymer, or a ceramic such as alumina or zirconia, and is preferably formed of zirconia ceramic. Specifically, partial stabilization mainly comprising tetragonal crystals containing ZrO ₂ as a main component and containing at least one of Y ₂ O ₃ , CaO, MgO, CeO ₂ , Dy ₂ O _{3 and the} like as a stabilizer. Zirconia ceramics are preferably used, and such partially stabilized zirconia ceramics are advantageous in fixing by press-fitting because they have excellent wear resistance and moderate elastic deformation.

  As a processing method of the ferrule 2, first, when the ferrule 2 is formed from, for example, zirconia ceramics, a cylindrical or cuboid shaped body that becomes the ferrule 2 by a predetermined molding method such as injection molding, press molding, extrusion molding or the like in advance. After that, the molded body is fired at 1300 to 1500 ° C. and subjected to cutting or polishing to a predetermined dimension. Note that a predetermined shape may be formed in advance on the formed body by cutting or the like, and then fired.

  The end surface 8 at the tip of the fiber stub 3 is processed into a curved surface having a radius of curvature of about 5 to 30 mm in order to reduce the connection loss with the optical connector, and the end surface 9 is formed by the light emitted from an optical element such as an LD. 3 is mirror-polished to an inclined surface of about 4 to 10 ° in order to prevent reflected light that is reflected by the end face of 3 and returns to the optical element.

  Further, the sleeve 4 is made of a material such as zirconia, alumina, or copper. It is often made of a ceramic material such as zirconia, mainly considering wear resistance. As a processing method, for example, when forming with a ceramic material such as zirconia, a cylindrical or columnar molded body that becomes the sleeve 4 is obtained in advance by a predetermined molding method such as injection molding, press molding, extrusion molding, and the like. The molded body is fired at 1300 to 1500 ° C. and subjected to cutting or polishing to a predetermined size. Note that a predetermined shape may be formed in advance on the formed body by cutting or the like, and then fired.

  In addition, the surface roughness of the inner diameter of the sleeve 4 is preferably an arithmetic average roughness (Ra) of 0.2 μm or less in consideration of the insertability, and the tolerance of the outer diameter of the fiber stub 1 and the inner diameter of the sleeve 4 is to obtain a low connection loss. The inner diameter of the sleeve 4 is preferably designed to have an insertion force of 0.98 N or more in order to securely hold the fiber stub 1.

  Furthermore, since the holder 5 is often welded to the case 24 (see FIG. 4) as an optical module, it is made of a material that can be welded, such as stainless steel, copper, iron, and nickel. Stainless steel is mainly used in consideration of corrosion resistance and weldability.

  Furthermore, the sleeve case 6 is made of a wide variety of materials such as stainless steel, copper, iron, nickel, plastic, zirconia, and alumina. In the present invention, since it is fixed through the insertion pin, a ceramic that can control the size of D2 with high accuracy is preferable. Further, when the sleeve case 6 is fixed to the holder 5 by welding, a stainless steel material such as SUS304 is preferable, and when soldering, a metal of the same material as the holder is preferable.

  Such an optical receptacle 7 can be suitably used as an optical connector.

The optical connector can be obtained by inserting the plug ferrule 10 into the sleeve 4 from the insertion portion 6a of the sleeve case 6 so as to abut the fiber stub 1, and as described above, the inner diameter of the sleeve case 6 and the sleeve 4 is affected. In addition, since the centers coincide with each other, an optical connector with a small connection loss can be obtained, and the dimensional difference between the outer diameter D3 of the plug ferrule 10 and the inner diameter D2 of the insertion 6a of the sleeve case 6 is as small as 50 μm or less. can do. As a result, even when a load is applied to the plug ferrule 10 in the direction perpendicular to the optical axis, even if a load in the direction perpendicular to the optical axis is applied to the sleeve 4, no displacement occurs, and deformation can be suppressed. Connection between optical fibers can be stabilized.

  Further, the optical receptacle 7 can be suitably used in a receptacle type optical module provided with optical elements such as a lens and a laser on the rear end side of the fiber stub 1, and the optical output from the laser is used for the plug ferrule 10 as described above. Even when a load is applied in a direction perpendicular to the optical axis, a stable light output can be stably transmitted from the fiber 3 to the fiber fixed to the plug ferrule 10.

  Next, examples of the present invention will be described.

  As an example of the present invention, an LC optical receptacle shown in FIG. 1 was produced. At that time, the difference between the inner diameter D2 of the insertion portion 6a of the sleeve case 6 and the inner diameter D1 of the sleeve 4 was set to 40 μm ± 10 μm.

  The ferrule 2 used for the fiber stub 1 is made of zirconia ceramics, a cylindrical ceramic molded body was obtained by extrusion molding, baked in a firing process, and cut to obtain a ferrule sample having the shape shown in FIG.

  The optical fiber 3 is inserted and fixed in the through-hole of the ferrule 2 obtained in this way, the front end surface is mirror-polished to a curved surface with a curvature radius of about 20 mm, and the rear end portion on the opposite side is light emitted from an optical element such as an LD. In order to prevent the reflected light from being reflected at the tip of the optical fiber and returning to the optical element, mirror polishing was performed on an inclined surface of 8 ° to obtain a fiber stub 1.

  The rear end side of the fiber stub 1 was press-fitted and fixed to a metal holder 5, and then the sleeve 4 was inserted. Next, the sleeve case 6 having a flange is inserted into the holder 5 with the pin 8 having an outer diameter larger than 1.249 ± 0.0007 mm being inserted into the LC connector plug ferrule as shown in FIG. The sleeve case 6 and the holder 5 were bonded and fixed.

  As a comparative example, a receptacle in which the sleeve case 6 and the holder 5 were press-fitted and fixed was manufactured. In this case, the difference between the inner diameter D2 of the sleeve case 6 and the inner diameter D1 of the sleeve 4 is set to 200 um for processing accuracy of concentricity of each component.

  Then, a plug ferrule of an optical connector was inserted from the tip side of the optical receptacle sample completed as described above, and a load was applied to the plug ferrule 10 in the direction perpendicular to the optical axis, and connection loss and return loss were measured.

Table 1 shows the connection loss measurement results. In Table 1, a graph with a value indicated by ▲ indicates a connection loss of the embodiment of the present invention, and a graph with a value indicated by ■ indicates a comparative example.

  From Table 1, in the optical receptacle according to the embodiment of the present invention, the PC junction is maintained up to a load of 600 gf, and the insertion loss is maintained at 0.5 dB or less. Further, it was confirmed that the return loss was maintained at 40 dB or more.

  On the other hand, in the comparative example, the connection loss increases rapidly when the load exceeds 300 gf. In addition, it was confirmed that the PC bond was detached at a load of 300 gf, and the return loss was rapidly reduced.

It is sectional drawing which shows one Embodiment of the optical receptacle of this invention. It is sectional drawing for demonstrating the assembly method of the optical receptacle of this invention. (A)-(c) is sectional drawing which shows other embodiment of the optical receptacle of this invention. It is sectional drawing which shows the optical module using the conventional optical receptacle.

Explanation of symbols

1: Fiber stub 2: Ferrule 3: Optical fiber 4: Sleeve 5: Holder 6: Sleeve case 6a: Insertion portion 7: Optical receptacle 8: Adjustment pin 10: Plug ferrule 14: Optical receptacle 15: Plug ferrule 16: Fiber stub 17 : Ferrule 18: Optical fiber 19: Sleeve 19 a: Sleeve case insertion part 20: Holder 21: Sleeve case 22: Optical element 23: Lens 24: Case 25: Collar part D1: Sleeve inner diameter D2: Sleeve case insertion part inner diameter D3: Plug Ferrule outer diameter A: Clearance between holder and sleeve case

Claims (5)

A fiber stub that has an optical fiber fixed to the through-hole of the ferrule is press-fitted and fixed to the holder, and a sleeve for holding the plug ferrule connected to the tip surface of the fiber stub is attached to the tip of the fiber stub. An optical receptacle in which the outer periphery of the sleeve is held by a sleeve case and the rear end side of the outer periphery of the sleeve case is held by a holder, and a clearance is provided between the rear end side of the outer periphery of the sleeve case and the holder. An optical receptacle, comprising: 2. The optical receptacle according to claim 1, further comprising a flange portion that joins a front end surface of the outer periphery of the holder on a rear end side of the outer periphery of the sleeve case. 3. The optical receptacle assembly method according to claim 1, wherein an adjustment pin having an outer diameter equivalent to that of a plug ferrule is inserted into the sleeve case in advance, and the adjustment pin is inserted into the sleeve, and then the sleeve A method of assembling an optical receptacle, wherein the tip of the fiber stub is inserted and positioned and fixed. An optical connector comprising a plug ferrule connected to the optical receptacle according to claim 1. An optical module comprising a casing housing an optical element attached to the rear end side of the optical connector according to claim 4.

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