JP2005338409A - Optical receptacle and optical module using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical module for achieving high coupling efficiency and downsizing. <P>SOLUTION: A front fiber stub and a rear fiber stub connected by fixing one optical fiber to the two through holes of ferrules are fixed in a holder having a through hole, and a split sleeve is fixed to the top end of the front fiber stub. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical receptacle using an optical fiber fixture to which an optical fiber used for optical communication or the like is fixed, and an optical module using the optical receptacle.

  Conventionally, in an optical module, for example, in a photodiode module (hereinafter referred to as a PD optical module), the return light reflected to the optical fiber causes a malfunction of the device.

  In addition, in the semiconductor laser module (hereinafter referred to as the LD optical module), the reflected return light to the semiconductor laser has caused a problem of unstable oscillation of the semiconductor laser.

  As a method for preventing reflected return light, in the optical fiber, the end face is polished at a predetermined angle to suppress reflected return light due to Fresnel reflection, or in the reflection from the light receiving surface of the PD, the PD is arranged obliquely. Reflected return light was suppressed.

  FIG. 8A is a cross-sectional view of a conventional lens translation PD optical module 25 in which the position of the lens 31 is translated from the central axis of the fiber stub 21.

  The front end 21a of the fiber stub 21 into which the optical fiber 24 is inserted is subjected to curved processing for connection to a plug ferrule (not shown), and the rear end 21b is polished at a predetermined angle to prevent reflected return light. Has been.

  A coupling lens 31 is disposed between the optical fiber 24 and the light receiving surface of the PD 33 so as to receive the signal light S1 on the light receiving surface of the PD 33, and the coupling lens 31 is inclined so as not to be affected by the aberration. It is arranged at the center of the optical axis emitted to.

  The signal light S1 is emitted obliquely from the rear end portion 21b of the fiber stub 21, passes through the lens 31, and enters the light receiving surface of the PD 33 (see Patent Document 1).

  FIG. 8B is a cross-sectional view of a conventional lens coaxial PD optical module 26 in which the position of the lens 31 is arranged on the central axis of the fiber stub 21.

  The front end 21a of the fiber stub 21 into which the optical fiber 24 is inserted is subjected to curved processing for connection to a plug ferrule (not shown), and the rear end 21b is polished at a predetermined angle to prevent reflected return light. Has been.

  A coupling lens 31 is disposed between the optical fiber 24 and the light receiving surface of the PD 33 so as to receive the signal light S1 on the light receiving surface of the PD 33, and the coupling lens 31 has a simplified downsizing structure, so that the fiber stub 21 is provided. It is arranged on the central axis.

The signal light S1 is emitted obliquely from the rear end portion 21b of the fiber stub 21, passes through the lens 31, is incident on the light receiving surface of the PD 33, and the light receiving surface of the PD 33 is disposed obliquely to prevent reflected return light. (See Patent Document 2).
Japanese Patent Laid-Open No. 11-295559 Japanese Patent Laid-Open No. 10-268164

  However, in the case of Patent Document 1, although it is effective, the lens and the PD must be moved in parallel, and it is difficult to offset the metal fitting.

  In addition, there is a problem that the outer shape of the optical module is increased by the amount of parallel movement, and this has been reversed from the recent demand for miniaturization. This problem of miniaturization is also a problem in the LD optical module. It was.

  In the case of Patent Document 2, since the lens and the PD are arranged on the same axis without offset, it is effective for downsizing the optical module, but the light receiving surface of the PD must be arranged obliquely. It was difficult to implement PD.

  Further, since the signal light does not pass through the center of the lens, there is a problem that the coupling efficiency is low due to the large influence of lens aberration.

  In particular, the light-receiving surface of a high-speed compatible PD, which has recently been required, has an extremely small range of 20 μm, and the influence of aberration has been a problem that greatly affects the coupling efficiency.

  Furthermore, when the conventional fiber stub is pressed into the holder by pressing the front end portion, the rear end portion is obliquely processed, so that there is variation in the press-fitting allowance.

  In addition, when the rear end portion is pressed into the holder, the rear end portion is processed obliquely, so that the press-fitting becomes unstable, and the fiber stub is chipped or pressed obliquely.

  Further, in the fiber stub, if the position of the front end portion is determined, the position of the rear end portion is inevitably determined by the length of the fiber stub, and there is a problem that the position of the rear end portion cannot be finely adjusted.

  In the fiber stub, the clad light in which the signal light passes through the clad (not shown) of the optical fiber has been a problem as noise.

  In view of the above problems, the optical receptacle of the present invention fixes the front fiber stub and the rear fiber stub that are connected by fixing the same optical fiber to the through holes of the two ferrules, and fixes the front fiber stub to the holder having the through holes. A split sleeve is fixed to the tip of the fiber stub.

  Further, the optical fiber between the front fiber stub and the rear fiber stub is curved.

  Further, the rear end portion of the front fiber stub is a flat surface.

  The fiber end face of the rear end portion of the latter-stage fiber stub is inclined at a predetermined angle with respect to the central axis of the through-hole of the latter-stage ferrule.

  Further, the central axis of the through hole of the ferrule of the latter-stage fiber stub is in a position translated by a predetermined distance with respect to the central axis of the through-hole of the ferrule of the preceding stage fiber stub.

  Further, the distance is 100 μm to 300 μm.

  Further, the center axis of the through hole of the ferrule of the latter-stage fiber stub is inclined at a predetermined angle with respect to the center axis of the through-hole of the ferrule of the preceding stage fiber stub.

  Moreover, said angle is 2-5 degrees, It is characterized by the above-mentioned.

  Furthermore, the optical receptacle is attached to a case having an optical element.

  According to the optical receptacle of the present invention, the incident / exit position of the signal light can be freely set without changing the central axis of the fiber stub facing the plug ferrule.

  Further, the clad light which is noise can be removed, and further, the expansion and contraction of the product due to the temperature change is allowed by the expansion and contraction of the optical fiber, so that it is possible to realize an optical receptacle having no characteristic deterioration even when the environment changes.

  Further, since the rear end portion of the ferrule at the front stage is planar, the press-fitting allowance is constant, so that the press-fitting does not vary and stable press-fitting can be performed.

  Further, since the fiber end face of the latter fiber stub is inclined at a predetermined angle with respect to the central axis of the through hole of the latter ferrule, reflected return light at the fiber end face can be prevented.

  Further, the signal light passes through the center of the lens, and the influence of aberration can be greatly reduced.

  Further, the signal light is parallel to the central axis of the preceding fiber stub, so that the coupling loss can be extremely reduced in the LD optical module.

  Furthermore, the optical module of the present invention is characterized in that the optical receptacle is attached to a case having an optical element.

  As described above, according to the present invention, a lens and an optical element can be arranged on the central axis of the optical receptacle, so that the optical module can be miniaturized, and an optical module with high coupling efficiency that is extremely resistant to lens aberration can be achieved.

  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 the optical receptacle 9 of the present invention, the front fiber stub 1a and the rear fiber stub 1b are independently attached. Since the front fiber stub 1a is joined to a plug ferrule (not shown), the through hole 2c has a front fiber. The center axis of the stub 1a is processed.

  The through-hole 3c of the latter-stage fiber stub 1b can be processed into a free position in relation to the optical module, and the position of the optical fiber 4 fixed to the through-hole 3c is determined by the position of the through-hole 3c.

  The structure and assembly method of the optical receptacle 9 will be described.

  The front fiber stub 1a is composed of the front ferrule 2 and the optical fiber 4 and is joined to the plug ferrule. Therefore, the front end portion 2a is curved, and the rear fiber stub 1b is composed of the rear ferrule 3 and the optical fiber 4. In order to prevent reflected return light, the rear end portion 3b is polished together with the fiber end surface 4a at a predetermined polishing angle α.

  The parallel movement X of the optical fiber 4 of the rear fiber stub 1b can be freely set by processing the through hole 3c of the rear ferrule 3 at an appropriate position.

  As a fixing method of the front fiber stub 1a, for example, in press-fitting fixation, the press-fitting allowance T1 of the front fiber stub 1a is preferably 0.5 mm to 2.0 mm. If the press-fitting allowance T1 is less than 0.5 mm, the fixing strength of the front fiber stub 1a is low, and there is a possibility that the front fiber stub 1a may move due to joining with the plug ferrule.

  Further, when the press-fitting allowance T1 exceeds 2.0 mm, the pressure input of the front fiber stub 1a is too high, and the front fiber stub 1a and the holder 6 may be deformed.

  Further, the thickness T2 of the rear fiber stub 1b is not particularly restricted, and the rear fiber stub 1b has a structure in which no stress is applied from the outside after being fixed. Therefore, the fixing strength capable of withstanding a mechanical environment test such as vibration or impact on the product. If there is.

  The front-stage fiber stub 1a is fixed to the holder 6 from the front end portion 2a direction, and the press-fitting direction of the front-stage fiber stub 1a is determined from the direction of the front end portion 2a or the rear end portion 2b depending on the fixing method of the rear-stage fiber stub 1b. either will do.

  Since the rear end 2b has a planar shape, the press-fitting allowance T1 is constant, and the press-fitting does not vary and stable press-fitting can be performed.

  The rear fiber stub 1b is processed to be smaller than the outer diameter of the front fiber stub 1a to be press-fitted into the holder 6, and the optical fiber 4 is bent at an optimal position and fixed with an adhesive 8.

  Since the rear fiber stub 1b can fix the optical fiber 4a at an optimum position with respect to the longitudinal direction of the optical axis, the alignment can be simplified when forming an optical module.

  Further, by bending the optical fiber 4, the clad light which is noise can be removed, and further, expansion and contraction of the product due to a temperature change is allowed by the expansion and contraction of the optical fiber 4. Become.

  Then, the sleeve 5 is inserted into the front fiber stub 1a, and the sleeve case 7 is fixed to the holder 6 to complete.

  As described above, the optical receptacle 9 in which the optical fiber 4 of the rear fiber stub 1b is translated is often used mainly for PD modules.

  2A and 2B are cross-sectional views showing an embodiment of the assembly of the optical receptacle of the present invention.

  FIG. 2 (a) shows that the front fiber stub 1 a is fixed to the holder 6.

  The front fiber stub 1 a and the rear fiber stub 1 b are respectively subjected to curved surface processing and oblique polishing, and the outer diameter of the rear fiber stub 1 b is smaller than the inner diameter of the holder 6, so that the front fiber stub 1 a is fixed to the holder 6. The rear fiber stub 1b can have a degree of freedom inside the holder 6.

  The position of the front fiber stub 1 a is determined by the plug ferrule insertion length L 1 and is adjusted by the positioning portion 17 a of the jig 17. By changing the dimension of the positioning part 17a, the position of the front fiber stub 1a can be freely changed.

  FIG. 2 (b) shows that the rear fiber stub 1 b is fixed to the holder 6.

  Adhesive 8 is applied to the gap formed between the rear fiber stub 1b and the holder 6, and the position of the rear fiber stub 1b is adjusted to the position of the optical axis length L2 by the positioning portion 18a of the jig 18. Since the position of the rear fiber stub 1b is also determined by the positioning unit 18a, the position of the front fiber stub 1a can be freely changed by changing the size of the positioning unit 18a.

  The positioning portion 17a and the positioning portion 18a are preferably provided with counterbores or the like so as not to damage the optical fiber 4.

  Thus, the positioning of the rear fiber stub 1b can be freely set regardless of the position of the front fiber stub 1a, and the optical axis length L2 is constant. Alignment can be simplified.

  FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

  The through hole 13c of the ferrule 13b of the rear fiber stub 11b is inclined by a correction angle β with respect to the central axis of the front fiber stub 11a. When the fiber end face 4a is at the polishing angle α and the through hole 13c is parallel to the central axis with the front fiber stub 11a, the optical axis of the fiber end face 4a is inclined with respect to the central axis of the front fiber stub 11a. In order to correct and make the optical axis of the fiber end surface 4a parallel to the central axis of the front fiber stub 11a, the through hole 13c of the rear ferrule 11b is inclined at a correction angle β.

  In the LD optical module, when the signal light emitted from the LD is not parallel to the optical axis of the optical receptacle 19, coupling loss occurs at the fiber end face 4a. However, by making the optical axis of the optical receptacle 19 parallel to the signal light The coupling loss due to the angle shift is reduced, and a highly coupled optical module can be realized.

  4 (a) and 4 (b) are cross-sectional views showing an embodiment of another fixing method in the latter stage fiber stub of the present invention.

  FIG. 4 (a) shows the rear fiber stub 1 b fixed to the holder 6 using the holding member 10.

  FIG. 4B shows the rear fiber stub 1b fixed to the counterbore 6a of the holder 6 and the rear end 3b having a polishing angle α.

  A long optical fiber 4 is fixed to the front ferrule 2, the front end portion 2 a is curved to complete the front fiber stub 1 a, and the front fiber stub 1 a is fixed to the holder 6.

  The rear ferrule 3 is fixed to the counterbore 6a of the holder 6 through the optical fiber 4 jumping out of the holder 6 to the rear ferrule 3, the optical fiber 4 is fixed to the rear ferrule 3, and the rear fiber stub 1b is polished at an angle α. Then, the rear end surface 3b of the rear stage is polished, and the optical receptacle 39 is completed.

  FIG. 5 is a cross-sectional view showing an embodiment of another fixing method of the optical fiber 4 in the rear fiber stub 1b of the present invention.

  The rear end 3b of the fiber stub 1b in FIG. 5 does not have a polishing angle because the fiber end surface 4a independently has a polishing angle α.

  A long optical fiber 4 is fixed to the front ferrule 2, the front end 2a is curved to complete the front fiber stub 1a, and the optical fiber 4 jumping out behind the front fiber stub 1a is cut to a predetermined length. Then, polishing is performed at a polishing angle α.

  The front fiber stub 1 a is fixed to the holder 6, the rear ferrule 3 is fixed to the counterbore part 6 a of the holder 6 through the optical fiber 4 jumping out from the holder 6 to the rear ferrule 3, and the optical fiber 4 is attached to the rear ferrule 3. The fiber stub 1b is manufactured by fixing, and the optical receptacle 49 is completed.

  The fixing position of the rear fiber stub 1 b is not limited to the counterbore portion 6 a of the holder 6, but may be the inner diameter portion of the holder 6.

  FIG. 6 is a cross-sectional view showing another embodiment of the optical receptacle of the present invention, in which a lens 31 is built in the optical receptacle 59.

  The front fiber stub 1a, the rear fiber stub 1b, and the lens 31 are coaxially disposed on the inner diameter of the holder 6. When the lens is disposed, it may be disposed on the optical element side or on the optical receptacle side. However, if it is arranged in the holder on the optical receptacle side, various parts can be arranged coaxially very easily.

  7A and 7B are cross-sectional views showing an optical module using the optical receptacle of the present invention. FIG. 7A is a PD optical module that receives the signal light S1, and FIG. 7B is a signal light. The LD optical module emitting S2 is shown, and the arrow in the figure indicates the traveling direction of the signal light.

  7A, the lens 31 is arranged on the central axis of the optical receptacle 9, and the through hole 3c of the rear fiber stub 1b is located at the center of the lens 31 in consideration of the optical axis inclination due to the polishing angle α of the optical fiber 4a. A predetermined parallel movement is performed so that the signal light S1 enters.

  At the rear end of the optical receptacle 9, an optical element module in which a lens 31 and a PD 33 are integrated in a casing 32 is fixed by YAG welding, an adhesive, or the like, thereby forming a PD optical module 15.

  The parallel movement X is preferably 100 μm to 300 μm, and within this range, for example, when the lens 31 is φ1.25 or φ1.5 and has the same magnification, the signal light S1 passes through the center of the lens 31 and has an aberration. The impact can be greatly reduced. When the translation X is less than 100 μm, the lens 31 is affected by the aberration, and the reflected return light from the light receiving surface of the PD 33 is coupled again at the fiber end surface 4a, resulting in poor characteristics.

  On the other hand, when the translation X exceeds 300 μm, it is also affected by the aberration of the lens 31 and the coupling efficiency is lowered and the characteristics are deteriorated.

  In FIG. 7B, the lens 31 is disposed on the central axis of the optical receptacle 19.

  The through hole 13c of the rear fiber stub 1b has a predetermined correction angle β such that the signal light S2 of the LD 34 and the optical axis of the rear fiber stub 1b are coaxial in consideration of the optical axis inclination due to the polishing angle α of the fiber end face 4a. It has been subjected. The polishing angle α of the fiber end face 4a for preventing reflected return light is preferably 4 ° to 11 °.

  When the polishing angle is less than 4 °, the reflected return light cannot be removed at the end face of the fiber and returns to the optical fiber to prevent reflection, and when the polishing angle exceeds 11 °, the coupling efficiency decreases. Therefore, the correction angle β is preferably 2 to 5 ° from the range of the polishing angle α.

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

  Similarly, the ferrule 2 constituting the latter-stage fiber stub 1b is made of a metal such as stainless steel or phosphor bronze, a plastic such as an epoxy or a liquid crystal polymer, or a ceramic such as alumina or zirconia. Since the rear fiber stub 1b is not subjected to external stress due to the joining with the plug ferrule like the front fiber stub 1a, the fixing strength is not so necessary. For this reason, the material can be selected according to the use such as a material with low material cost, a material that can be easily polished, and a material that has high adhesiveness when fixed with an adhesive.

  As the processing method of the preceding ferrule 2, first, when the former ferrule 2 is formed from, for example, zirconia ceramics, a cylindrical shape that becomes the former ferrule 2 by a predetermined forming method such as injection molding, press molding, extrusion molding or the like in advance. Alternatively, a rectangular parallelepiped shaped body is obtained, and then the shaped 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.

  The front end portion 2a of the front fiber stub 1a is processed into a curved surface having a radius of curvature of about 5 to 30 mm in order to reduce connection loss with the plug ferrule.

  Further, in order to prevent reflected return light, the optical fiber 4 is polished to about 4 to 11 ° together with the rear end portion 3b of the rear fiber stub 1b. Even if the fiber end face 4a is polished to about 4 to 11 °, it can prevent reflected return light.

  The sleeve 5 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 the processing method, for example, when forming with a ceramic material such as zirconia, a cylindrical or columnar molded body that becomes the split sleeve 4 is obtained in advance by a predetermined molding method such as injection molding, press molding, extrusion molding, Thereafter, the molded body is fired at 1300 to 1500 ° C. and cut or polished 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.

  Further, when the sleeve 5 is, for example, a split sleeve, the surface roughness of the inner diameter is preferably an arithmetic average roughness (Ra) of 0.2 μm or less in consideration of the insertability, and the outer diameter tolerance of the front fiber stub 1a and the inner diameter tolerance of the sleeve 5 are desirable. In order to obtain a low connection loss, ± 1 μm or less is desirable, and the inner diameter dimension of the sleeve 5 is desirably designed to have an insertion force of 0.98 N or more in order to securely hold the fiber stub 1a.

  Furthermore, since the holder 6 is often welded to the casing 32 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 7 is made of a wide range of materials such as stainless steel, copper, iron, nickel, plastic, zirconia, and alumina. When the sleeve case 7 is fixed to the holder 6 by welding, a stainless material such as SUS304 is preferable. In the case of soldering, a metal made of the same material as the holder is preferable.

  Next, examples of the present invention will be described.

  As an example of the present invention, five PD optical modules shown in FIG.

  The ferrule 2 and ferrule 3 used for the fiber stub 1a and fiber stub 1b are made of zirconia ceramics. A cylindrical ceramic molded body is obtained by extrusion molding, and is baked and hardened by a firing process. A sample having the shape shown in FIG.

  The optical fiber 4 is inserted and fixed in the through-holes of the ferrule 2 having the through-hole 2c thus obtained on the central axis and the ferrule 3 having the through-hole 3c translated to a predetermined position with respect to the central axis, The front end 2a of the front fiber stub 1a is mirror-polished to a curved surface with a curvature radius of about 20 mm, and the rear end 3b of the rear fiber stub 1b reflects light emitted from the optical element 31 such as an LD to the optical element 31. In order to prevent the reflected light from returning, mirror polishing was performed on an inclined surface of 8 ° to obtain a rear fiber stub 1b.

  The rear end 2b of the front fiber stub 1b was press-fitted and fixed to the metal holder 6, and then the sleeve 5 was inserted.

  Next, the sleeve case 7 was press-fitted and fixed to the holder 6.

  Adhesive 8 was applied between the rear fiber stub 1b and the holder 6, and the rear fiber stub 1b was fixed at a predetermined position.

  Thereafter, the optical receptacle 9 and the casing PD element 33 were optically aligned and then fixed by YAG welding to produce a PD optical module 15.

  In addition, as a comparative sample, the same parts other than the fiber stub were used, and five conventional lens coaxial PD optical modules 26 in which the fiber stub was not independent were produced.

The light receiving sensitivity of the product of the present invention completed as described above and the conventional product was measured.

  From Table 1, the light receiving sensitivity of the PD optical module 15 of the present invention is Ave. = 0.945 A / W, the light receiving sensitivity of the conventional lens coaxial PD optical module 26 is Ave. = 0.878 A / W.

  The PD optical module 15 of the present invention can obtain high light receiving sensitivity without being affected by the aberration of the lens 31, and further has the same outer shape as the lens coaxial PD optical module 26 of the conventional product, and is also downsized. Yes.

It is sectional drawing which shows one Embodiment of the optical receptacle of this invention. (A), (b) is sectional drawing which shows one Embodiment of the assembly of the optical receptacle of this invention. It is sectional drawing which shows other embodiment of the optical receptacle of this invention. (A), (b) is sectional drawing which shows other embodiment in the back | latter stage fiber stub of this invention. It is sectional drawing which shows other embodiment of the optical fiber in the back | latter stage fiber stub of this invention. It is sectional drawing which shows other embodiment in the optical receptacle of this invention. (A), (b) is sectional drawing which shows the optical module using the optical receptacle of this invention. (A), (b) is sectional drawing which shows the optical module using the conventional optical receptacle.

Explanation of symbols

1a, 11a: front fiber stub 1b, 11b: rear fiber stub 2: front ferrule 2a: front end 2b: rear end 2c, 3c: through hole 3, 13: rear ferrule 3a: front end 3b: rear end 4: Optical fiber 4a: Fiber end face 5: Sleeve 6: Holder 6a: Counterbore part 7: Sleeve case 7a: Sleeve case rear end part 8: Adhesives 9, 19, 29, 39, 49, 59: Optical receptacle 10: Holding Member 15: PD optical module 16: LD optical module 17, 18: jig 17a, 18a: positioning part 21: fiber stub 21a: tip part 21b: rear end part 22: ferrule 25: lens offset PD optical module 26: lens coaxial PD optical module 31: lens 32: casing 33: PD (photodiode)
34: LD (semiconductor laser)
α: Polishing angle β: Correction angle X: Parallel movement L1: Plug ferrule insertion length L2: Optical axis length T1: Press-fit allowance T2: Thickness

Claims (9)

A front fiber stub and a rear fiber stub that are connected by fixing the same optical fiber to the through holes of the two ferrules are fixed to a holder having a through hole, and a split sleeve is fixed to the tip of the front fiber stub. Optical receptacle characterized by. 2. The optical receptacle according to claim 1, wherein an optical fiber between the front fiber stub and the rear fiber stub is curved. 3. The optical receptacle according to claim 1, wherein a rear end portion of the front fiber stub is a flat surface. The optical receptacle according to any one of claims 1 to 3, wherein a fiber end surface of a rear end portion of the rear fiber stub is inclined at a predetermined angle with respect to a central axis of a through hole of a rear ferrule. The center axis of the through hole of the ferrule of the latter stage fiber stub is in a position translated from the center axis of the through hole of the ferrule of the preceding stage fiber stub by a predetermined distance. Optical receptacle according to crab. The optical receptacle according to claim 5, wherein the distance is 100 μm to 300 μm. The central axis of the through hole of the ferrule of the latter stage fiber stub is inclined at a predetermined angle with respect to the central axis of the through hole of the ferrule of the preceding stage fiber stub. Light receptacle. The optical receptacle according to claim 7, wherein the angle is 2 to 5 °. An optical module comprising the optical receptacle according to claim 1 attached to a case having an optical element.

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